ANL-7180.txt

ANL-7180 /(7\ W ANL-7180
@ D{ MASILR

Argonne JAational Laboratory

CATALOG OF NUCLEAR REACTOR CONCEPTS

Part I. Homogeneous and
Quasi-homogeneous Reactors

Section Y. Reactors Fueled with
Uranium Hexafluoride, Gases, or Plasmas

by

Charles E. Teeter, James A. Lecky,
and John H. Martens

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RELEAS

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ANNOUNCEMENT

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RELEASED FOR

j STRACTS
IN NUCLEAR SCIENCE ABSTRA

.

ARGONNE NATIONAL LABORATORY
9700 South Cass Avenue
Argonne, Illinois 60439

CATALOG OF NUCLEAR REACTOR CONCEPTS

Part 1. Homogeneous and
Quasi-homogeneous Reactors

Section V. Reactors Fueled with

"Uranium Hexafluoride, Gases, or Plasmas

by

- Charles E, Teeter, James A. Lecky,
and John H. Martens

Technical Publications Department

March 1966

Operated by The University of Chicago
under
Contract W-31-109-eng-38
with the
U. S. Atomic Energy Commission

ANL-7180

Reactor Technology
(TID-4500) ,

AEC Research and
Development Report

CFSTI PRICES

H.C. $500 ; MN 45
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Preface.

TABLE OF CONTENTS

Plan of Catalog of Nuclear Reactor Concepts.

List of Reactor Concepts . . . . . . , . .

SECTION V. REACTORS FUELED WITH URANIUM HEXAFLUORIDE,
GASES, OR PLASMAS. . . . . . . « « « + . &

Chapter 1.
Chapter 2.
Chapter 3.

Introduction. . . . . .
Reactors Fueled with Uranium Hexafluoride

Reactors Fueled with Gases or Plasmas

13
37
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- PREFACE

This report is én additional sectioh in the Catalog of Nuclear Reactor
Concepts that was begun with ANL-6892 and continued in ANL-6909, ANL-7092, and
ANL-7138, As in the previous reports, the material is divided into chapters,
each with text and references, plus data sheets that cover the individual
concepts.: The plan of the catalog, with the report numbers for the sections
already issued, is given on the next page, which is .followed by pages listing
the concepts included in this section. B |

Dr. Charles E. Teeter, formerly employed by the Chicago Operations Office

~at Argonne, Illinois, is now affiliated with the Southeastern Massachusetts

Technological Institute, New Bedford, Mass. Through a consultantship arrange-

ment with Argonne National Laboratory, he is continuing -to help guide the

organization and compilation of this catalog.
We wish to acknowledge the assistance of Miss Ellen Thro in the prepara-

tion of this section.

J.H. M.,
March, 1966
PLAN OF CATALOG OF REACTOR CONCEPTS

General Introduction _ | ~ ANL-6892
Part I. - Homogeneous and Quasi-homogeneous Reactors
Sectioh I. Particulate-fueled Reactors . ANL-6892
Section II. Reactors Fueled with Homogeneous
Aqueous Solutions and Slurries . ANL-6909
Section IITI. Reactors Fueled with Molten-salt
Solutions ANL-7092
Section IV, Reactors Fueled with Liquid Metals ) ANL-7138
Section V. Reactors Fueled with Uranium Hexa- |
fluoride, Gases, or Plasmas This report
Section VI, Solid Homogeneous Rcactors
Part TI, Heterogeneous Reactors
Section 1. Reactors Cooled by Liquid Metals
Section TII. Gas-cooled Reactors
Section III. Organic-cooled Reactors
Section 1IV. Boiling Reactors
Section V, Reactors Cooled by Supercritical Fluids
Section VI. Water-cooled Reactors

Section VII. | Reactors Cooled by Other Fluids
Section VIII. Boiling-waler Reactuors

Section IX. Pressurized-water Reactors

Part III. Miscellaneous Reactor Concepts
REACTOR CONCEPTS DESCRIBED IN THIS REPORT

Name of Reactor

Hexafluoride Thermal Pile
Uranium Hexafluoride Thermal Pile
Uranium Hexafluoride Thermal Pile
Liquid Hexafluoride Pile

Proposed Hanford Circulated-
Hexafluoride Thermal Pile

U233 Hexafluoride Breeder
Hex P-9 Pile (UF6-D20 Pile)

Homogenebus, Circulating Liquid
UF¢ Fueled Pile

Circulating Liquid UFg Pile

Gaseous UFg Fueled, Gas Cooled
Power Pile '

Gaseous UF ¢ Fueled, Gas Cooled
Power Pile |

Water-Cooled, High Flux, UF¢
Fueled Pile

Circulating Gaseous UFg
Fueled Pile

Homogeneous, Circulating
Gaseous UF¢ Fueled Pile

Gaseous UF6-Fue1ed Reactor

Direct Expansion UFg-Fueled
Reactor

Direct Expansion UFg-Fueled
Reactor

UF6-Fue1ed Reactor for
Locomotive Propulsion

* Gaseous UF6 Reactor
UF6 Gas Phase Reactor
Gaseous-Fuel Fast Rreeder Reactor

Gaseous Reactor for Rocket
Propulsion

Cavity Reactor
Fission-plasma Reactor
Plasma Core Reactor
Fizzler Reactor

Fizzler Reactor for Rocket
Propulsion

Chapter No.

2
2
2
2

N

Hha

w W w w w

Data‘Sheet No.

1
,
3
4

Lun

Page
REACTOR CONCEPTS DESCRIBED IN THIS REPORT (Cont.)

Name of Reactor

Gas-Solid Fueled Reactor,
Series for Rocket Propulsion

Cavity Reactor

Gaseous Propulsion Reactor
Vortex Reactor

Coaxial Flow Reactor

Homogeneous Gas Phase¢ Magneto-
hydrodynamic Nuclear Reactor

‘Chapter No.

w w W W W

Data Sheet No.

Page
PART I, HOMOGENEQUS AND QUAST-HOMOGENEQUS REACTORS

SECTION V. REACTORS FUELED WITH URANIUM HEXAFLUORIDE, GASES, OR PLASMAS

Chapter 1.  Introduction

This section covers reactors fueled with uranium hexafluoride, either as
a gas or a liquid, and those fueled with other gases (such as vaporized fis-
sile metals) or with plasmas (ionized gases). Although uranium hexafluoride
is normally a solid or a gas (it sublimes at 56.4°C under atmospheric pressufel)
its use as a liquid by keeping the system under pressure has been proposed.
The liquid phase appears above the triple point of 147.3°F and 22 psia. The
critical point is at PC, 45.5 atm; and TC, 446°F.2 The reactors fueled with

UF, are included in Chapter 2. Reactors fueled with other gases or with

6
plasmas are in Chapter 3; in some of these, uranium hexafluoride is the
original form of the fuel.

The UF6-fue1ed reactors might be considered fairly conventional, in that
the liquid or gaseous fuel is in a reactor system resembling those previously
described for reactors fueled with molten salts or metals. The fuel may
either circulate for cooling or be cooled by another material. In the reactors
fueled with gaseous metals or with plasmas, on the other hand, the gaseous fuel,
at extremely high temperatures, mixes with a gas that is both a rocket propel-
lant and the reactor coolant. Sophisticated means are needed both to contain
and later to separate the two gases. Most of the concepts in this section are
for thermal reactors. Another moderator is therefore needed because with
fluorine alone as a moderator the critical mass would be excessive.

The advantages of UF, as reactor fuels were recognized early in the war-

6
time atomic energy program. It has a low cross section for parasitic neutron

capture. Like other fluid fuels, UF, can be used in simple reactor systems

and can be circulated to give heat tg a boiler or other heat outlet. Fuel
fabrication is not necessary, and both fission products and bred fissile
material can be removed by simple means. The gaseous fuels have the added
advantage that they are not limited by structural properties to any minimum
temperature. There are, however, difficulties with the systems described in
this section. Such problems as possible instability, corrosiveness, and

[isslon-product deposition with UF, and the need for special containment

6
methods for gases and plasmas at extremely high temperatures will be covered

in Chapters 2 and 3. Two difficulties common to both types of gaseous reactors
10

are that gases are poor conductors of heat and extremely large volumes are
needed to obtain a critical mass because of the low density of gases.

An early suggestion for the use of uranium hexafluoride as a reactor fuel
was in the concept by Anderson and Brown in 1942,3 They proposed using liquid
UF6°

thereafter. Concepts have been published intermittently since then, although

Several other concepts were advanced during World War II and shortly

no practical development has occured in the United States. Some of the
suggestions published are too incomplete for data sheets to be made. 1In
Russia, a 1ow;power experimental reactor fueled with gaseous UF6 began opera-
tion in 1957.

The reactors fueled with high-temperature gases, such as the vortex and
the plasma reactors, first received attention shortly atter the war, especially
for rocket propulsion. Several concepts have been published; much of this
work deals with the problem of separating the gaseous fuel and the propellant
gas. Work is continuing in this field, but details of some developments are

not available.5
11

References

W.D. Wilkinson, Uranium Metallurgy, Vol. 1, Uranium Process Metallurgy,

p. 553, Interscience Publishers, 1962,
J.W. Arendt, E.W. Powell, and H.W. Saylor, comps. and eds., A Brief

6
H.L. Anderson and H.S. Brown, Liquid UF6 Plant for the Production of
Element 94, CN-362, Metallurgical Laboratory, University of Chicago,

Nov. 27, 1942,

Guide to UF, Handling, K-1323, Union Carbide Nuclear Co., Feb. 18, 1957.

I.K. Kikoin, V.A. Dmitrievsky, Y.T. Glazkov, I.S. Grigoriev, B.G. Bubovsky,
and S.V. Kersnovsky, Experimental Reactor with Gaseous Fissionable Sub-

stance (UF6), Proc. 2nd U. N. Int. Conf, on Peaceful Uses of Atomic

Energy, 9, pp. 528-534, United Nations, N.Y., 1958.

R.S. Cooper, Advanced Nuclear Propulsion, Nuclear News, 7, No. 11, pp. 40-

41, Nov. 1964,

12

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13

Chapter 2. Reactors Fueled With Uranium Hexafluoride

Most of the concepts in this chapter are for thermal reactors. Use of
uranium hexafluoride alone is not practical, and a moderator must be used with
it. Gaseous (helium), liquid (heavy water or fluorocarbons), and solid (beryl-
lium or graphite) moderators have been suggested.

The early concepts for UF6 as a fuel employed either liquid or gaseous
forms. Later, use of the gaseous fuel predominated. The advantages of a gas
as fuel have been given in Chapter 1.

Some problems appear to need further investigation: stability of the
compound under irradiation; corrosion of containment materials, especially
under irradiation; settling out in the reactor of solid UF6, fission pfoducts,
or corrosion products; and the use of a moderator for which a reactor of rea-
sonable size is possible: for example, if heavy water were to be used as has
been suggested, a very large amount wofild be needed.‘

The only reactor reported to have actually operated with UF6 as fuel was
a Russian reactor that operated at low temperature (90°C) and low power (1.5 kW)¢1
The Russian investigators, Kikoin et al., found that the decomposition of the
UF6 could be hindered by adding chlorine trifluoride. No experience on the
stability under radiation at temperatures usual in power reactors has been
reported.

The corrosivity of UF6 toward metals has been investigated, but apparently
not under conditions of irradiation. Heymann and Kelling2 found that the cor-
rosion rates at 80°C are low for nickel, copper, Monel, aluminum, alloy steels,
and titanium alloys. For use at high temperatures, high-purity nickel and
Monel appear to be best, Langlois3 studied corrosién by UF6 at high tempera-
tures. High-purity nickel has the lowest corrosion rates above 800°C, and
these rates are compatible with industrial uses. Between 550° and 700°C,
however, corrosion of nickel and Monel by penetration along crystalline bound-
aries prohibits the use of these metals in this temperature range. Nickel of
the highest purity, in which impurities responsible for intergranular attack
are eliminated, should have greatly improved corrosion resistance. Dry UF6
is normally contained in nickel or Monel. Lane4 points out that the stability
under irradiation of the protective film on these metals has not been investi-
gated. _ _
In 1947, Hull5 described several concepts and discussed different aspects
of using UF, as fuel. He listed many advantages, most of which have been given

6

here already. Others he noted are: remote operation permits low-decontamination
14

ceparation, with consequent simplified processing; and elimination of cooling
permits a low inventory. He suggested hydrogen fluoride (b.p., 19.4°C),
deuterium fluoride, and fluorocarbons as liquid solvent-moderators for homo-
geneous reactors. Helium or fluorocarbons would be coolants; water or liquid
metals would have to be kept separate from the UF6 because of the vigorous
reactions that would occur on contact between them and the fuel. Graphite

reacts so vigorously with UF, that it also would have to be separated. For

6
containment materials, he suggested beryllium or nickel; aluminum or magnesium
could be used if the problem of attack by UF6 could be solved. Areas in which

he thought investigation was needed are: corrosion of metals by uranluw liesa=-

fluoride and fluorine; decomposition of UF, by fission-product fluorides, witLh

6
or without solvents; and heat transter by radiation and conduclivu through

is formation of gas bubbles

gaseous UF A possible problem with liquid UF

6°
that might cause instability. °

In 1962, Wethington6 proposed that research be carried out on a reactor
fueled with a solution of uranium hexafluoride in a fluorocarbon. He cited
the Russian experience and the work of others to show that although there
would be some decomposition of UF6 under radiation it could be controlled and
it would be no worse than that uf other compounds used in reactor technology.
The fluorocarbons were suggested as promising moderators because published
information indicates that they have good radiation stability. More investi-
gation, however, would be needed on Lfie coucept,

As mentioned in Part I, Section I, of this catalog, Kerze has suggested
that CaF2 particles might be fluidized with.a mixture of uranium hexafluoride
and tetrafluoromethane (CF4) to give a gaseous suspension. The feasibility of
such a system would depend upon the mixture having sufficient moderating pro-
perties, -

Another concept with uranium hexafluoride as a gaseous fuel has been dis-
cussed in Part I, Section I. Halik et al. proposed fluidizing Fine particles

of beryllium oxide moderator by the fuel gas.

Reactors Fueled With Liquid Uranium Hexafluoride

In 1942, Anderson and Brown,7’8 of the Metallurgical Laboratory of the
University of Chicago, suggested a reactor fueled with liquid uranium hexa-
fluoride, as well as two variants of the original design. The reactor would
be a breeder for producifig plutonium. 1In the original design, the fuel-
coolant-fertile material is natural or enriched 1iquid>UF6.- The fuel circulates
through tubes in a moderator of graphite or heavy water and goes to an external
15

heat exchanger. The tubes are of uranium lined fiith nickel dr other corroéion-
resistant metal of low neutron-absorption cross section. A power of more than
100 MW(t) was expected. In the first variant, the central portion of the
graphite matrix contains uranium rods, which are cooled by helium passing be-
tween the rods. At the periphery of the matrix are aluminum tubes containing

liquid UF,, which passes to an external heat exchanger. Breeding occurs in this

6’
outer region, which also serves as a reflector for the inner section of rods.
In the second variant, there is a central spherical void, filled with heavy

water, in the graphite matrix. The UF, circulates through tubes that are im-

bedded in the graphite and pass througg the heavy water. A power of more than
100 MW(t) was expected.

Two 1943 concepts from the Metallurgical Laboratory, University of Chicago,
are a Liquid Hexafluoride Pile and the Proposed Hanford Circulated-Hexafluoride,
Thermal Pile.9 Both are rated at 390 MW(t). 1In the first, the liquid UF6
circulates through tubes of aluminum in a graphite moderator and out to a heat
exchanger. This concept is a burner. 1In the second concept, the fuel circu-
lates through tubes, immersed in 25 tons of heavy water surrounded by a graphite
reflector, to an external heat exchanger. It is a breeder, with the fuel and
fertile material being natural uranium moderated by heavy water.

In the U233 Hexafluoride Breeder,10 suggested by Metallurgical Laboratory

staff members in 1944, a fluorocarbon is utilized to dissolve U233Fé, and
thorium is the reflector-breeding blanket. The fuel circulates in tubes through
the cylindrical core. The power is 100 to 200 MW(t).

A 1944 concept by Anderson is the Hex P-9 Pile (UF6-D

would require 686 tons of liquid UF6(”Hex"), probably highly enriched for a

2O pile).8’11’12 This

burner and natural uranium for a breeder, with 63 tons of heavy water ("P-9'")
as moderator. The fuel circulates through tubes in the moderator and out the
top to a heat exchanger. Temperature limits to prevent both solidification
and vaporization of the UF, are 75°C minimum and 150°C maximum.

Among the concepts described by Hull in 19475 were two for liquid UF6

fuel. 1In one, the fuel is.liquid UF, dissolved in either a liquid fluorocarbon

6
or deuterium fluoride. The fuel circulates for heat exchange and removal of
fission products. It has thorium tetrafluoride as fertile material. 1In the
second concept, the fertile material, thorium tetrafluoride, is present as a

fine powder within beryllium cylinders in a graphite bed.
16

Reactors Fueled With Gaseous Uranium Hexafluoride

In 1947, Hull5 described the use of gaseous uranium hexafluoride, pointing
out the advantages of the fluid fuel, and he described concépts originated by
staff members of the Clinton Laboratories (now QOak Ridge National Laboratory).
A preliminary study on such piles had been published earlier in the same year

by Hull and Miles.13

In one design, the fuel, U233 or U235 in UF6, is contained in porous
beryllium tubes surrounded by impervious beryllium tubes. The pores are for
trapping fission products. The tubes are within a graphite moderator core that
is either in the form of rods in the center ¢f a triangular lattice ot tuel
tubes or as annular tubes around them. The coolant, helium, circulates through
the spaces in the core and out to a heat exchanger. A blanket of thorium
powder in beryllium tubes within a graphite bed is the fertile material. Bred
fissile material is leached out of the fuel by slowly circulating fluorine
through the bed. The porous design of the fuel tubes, intended to facilitate
trapping of fission products, allows the products to be removed from the UF6
without chemical processing. This design was for a power of 96 MW(t).

In a modification of this design, the fuel circulates slowly through
aluminum tubes outside the reactor. These tubes have large pores that do not
trap the fission products. Thus removal of fission products is continuous,
permitting better neutron cconomy. Bccausc of their low cost, these aluminum
tubes can be discarded instead of being reprocessed, but their use results in
lower power potential. The power is 50 MW(t).

In a high-flux pile, the water coolant flows in an annulus between porous

233 or U235 as

aluminum rods and beryllium cylinders. The rods contain U
gaseous uranium hexafluoride. Water cooling of the rods, according to the
author, gives a high power output--32 MW(t)--but at a temperature too low for
economic value in generation of electrical power. The moderator would be either
water or beryllium. A reflector-blanket, like that in the previous design,
permits breeding.

The originators believed that the uranium bred in the reactor could be
removed fairly simply from the blanket of the finely powdered thorium fluoride
contained in beryllium tubes. A hot mixture of helium and fluorine flowing
through the powder would convert the products to fluorides. If the powder were
fine enough and the temperature high enough, the PaF5 and UF6 could diffuse
through the beryllium, be volatilized at the surface, and be carried away by
circulating gas. The UF, could be separated in a fractionating column con-

6
. . 2
tinuously as soon as the proactinium decays to U 33.

Ll
17

Two other concepts described were for reactors in which gaseous UF6'cir-
culates outside the reactor for removal of fission products and, presumably,
for heat exchange. Both would operate at 230°C or higher. This temperature
would avoid the need for excessive pressure. In one desigfi, the fuel circu-
lates through holes in a cylinder of beryllium moderator. The authors stated
that fission products would settle out of the gas onto surfaces within the -
reactor, but using the gaseous form of UF6 avoids the problem of gas. bubbles

that would occur with liquid UF In the other design, the reactor is homo-

geneous, with the moderator beigg a gas, helium or carbon tetrafluoride
(tetrafluoromethane). The operating pressure is 100 atm. The authors specify
a spherical reactor with a diameter of 17 meters, but they stated that it was
too large to be considered at that time. Breeding with a blanket would be
possible, but the blanket would have to be extremely large.

A 1947 suggestion by Goodman14 for a reactor fueled with gaseous UF6
included the use of fluorine to stabilize the UF6 and to act as additional
moderator. The fuel either circulates to an external heat exchanger or re-
mains fixed and is cooled by a coolant such as liquid metal passing through
coils.

In 1953 Kerner proposed the use of the direct expansion of UF6 in an
internal-combustion engine, a turbine, or a reciprocator, The gas is
briefly compressed to supercriticality with a piston; it heats up and pushes
back the piston. The gas returns to the core through a heat exchanger and a
pump.

Reactor concepts in which this direct expansion were utilized were ad-
vanced in 1953 by ‘Fortescue]'6 and in 1957 by Clasen..’17 In the 1953 concept,
the moderator is molten beryllium fluoride surrounding fuel tubes in a cylin-
drical nickel calandria. The reactor is under a pressure of 20 atm.. Cadium
absorbers in the heat exchangers were suggested for control of criticality
outside the core. 1In the 1957 concept, the fuel is within a beryllium core;
the turbine also is to be made of beryllium as much as possible. A graphite
reflector surrounds core and turbine. A blanket of U238F6 is suggested if
breeding is desired. A fast reactor is suggested as an alternative, but no
details are given.

235

The expansion of gaseous U ~"F, is the basis for another reactor, for

6
which few details are given, in which a piston compresses the gas fuel in each
18- , Lo .
end of a cylinder.'8 20 The compression causes criticality, and the gas ex-
pands to drive the piston to the opposite end, where the gas at that end ex-

pands. Thus a reciprocating action of the piston results. Each end of the
18

cylinder is surrounded by a moderator and reflector. Direct conversion of the
piston motion into electrical action by use of electromagnefic induction was
proposed° The application of the concept to locomotives has been suggested, and
in 1955 the USAEC awarded a contract for the study of a nuclear-powered recipro-
cating engine for locomotive propulsion to the Baldwin-Lima-Hamilton Corporation
and the Denver & Rio Grande Railroad.20 The chief problems visualized were in

startup and in handling UF

6‘
The only UF6-fue1ed reactor to be built and operated is the Russian low-
power [1.5 kW(t) ] experimental reactor, fueled with gaseous UF6. It went

1,21 ; ; . . .
’ Russian investigators reported that the reactor operated

critical in 1957.
satisfactorily. There was a pressure drop and a decrease in reactivity at a
higher power level, which was attributed to dissociation of the UF6 under 1r-
radiation. Adding chlorine trifluoride permitted stable operation. The fuel
is highly enriched uranium hexafluoride, the moderator is beryllium, and the
reflector is graphite. The fuel is within channels formed from aluminum tubes,.
Criticality is achieved by increasing the pressure. Control rods are provided,
The authors suggest that improved methods of plutonium breeding might be pos-
sible with the UF6 reactor. Some plutonium fluorides are not volatile, and
plutonium hexafluoride, which has a high vapor pressure, is unstable. Thus
special traps in the fuel-coolant system might be used to collect plutonium
fluorides. ,

A 1958 concept by Baron22 was for a circulating-fuel converter utilizing
slightly enriched uranium in the gaseous fuel as both fuel and fertile material.
The fuel flows by natural circulation through double-wall aluminum tubes set
within graphite blocks in the core; helium, the intermediate coolant, is in the
annulus between the tube walls and in an external heat exchanger to which the
fuel circulates. The fuel leaves the corc at 900°F. To maintain sufficient
fuel circulation, a core height of .25 feet is specified. The power is 35 MW(e).

9
Hammitt,"3

in 1960, described a concept for a fast breeder reactor in which
the UF6 fuel and the sodium coolant flow through parallel tubes made from a
nickel alloy. A blanket of fertile material surrounds the core. The power

given is 300 MW(t).
Status

vThefe appear to have been no sustained developmental programs leading to
reactor experiments for reactors fueled with uranium hexafluoride. The early
interest in uranium hexafluoride as a reactor fuel has resulted in compara-
tively few concepts and, aside from the low-power Russian reactor, apparently
no practical development. Recent concepté have been few. Questions of practi-
cal feéctor operation, such as stability and corrosivity of UF6 under operating

conditions of a power reactor, are not yet clarified.
20

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DATA SHEETS

REACTORS FUELED WITH URANIUM HEXAFLUORIDE

21
22

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23

No. 1 Hexafluoride Thermél Pile

Metallurgical Laboratory, University of Chicago

References: CN-362; U.S. Patent 2,990,354,

Originators: H.L. Anderson and H.S. Brown.

Status: Proposal, November 1942; pétent issued, 1961.

Details; Thermal neutrons, steady state, breeder, for production of Pu. Fuel-
coolant-fertile material: natural or enriched U in liquid UF6' Moderator:
graphite or DZO' Core arrangement: liquid UF6 circulates through tubes in
moderator matrix to external heat exchanger. If moderator is graphite blocks,
tubes are of U lined with Ni or other corrosion-resistant metal of low neutron-
absorption cross section. If moderator is D20, tubes are of U lined with alloys
of metals of low neutron-absorption cross section, such as Ni, Be, or Mg. With
D20, 223 tubes, 8 cm ID, in cylindrical core 3.31 m long, 3.6 m diameter; l.Q82
reproduction factor. With graphite, 1700 tubes, 4 cm ID, 8.30 cm long. Bred
Pu can be recycied as fuel or separated chemically., Control: Cd or boron
steel rods. Power: probably more than 100.MW(t). Breeding ratio: 1.029.
Code: 0312 12 31110 41 612 732 81X11 941 104

14 42 733 81X12

No. 2 Uranium Hexafluoride Thermal Pile

"Metallurgical Laboratory, University of Chicago

Referenqes: CN-362; U.S. Patent 2,990,354,

Originators: H.L. Anderson and H.S. Brown.
Status: PrOposal, November 1942;'patént issued, 1961.
Details: Variant of concept in Data Sheet No. 1. Central portion of graphite
matrix contains U rods cooled by helium, which passes through spaces between
rods. At.fieriphery of matrix, Al tubes concain:circulating:1iquiq-UF6;thich::“
passes to external heat exchanger. .Outer g'raphite-—UF6 system acts as reflector
to U-rod section and also serves as breeding section, from which Pu can be
extracted, |
Code: 0312 12 31110 41 612 732 81X11 941 109

31716 42 733 81X12
No. '3 Uranium Hexafluoride Thermal Pile

Metallurgical Laboratory, University of Chicago

References: CN-362; U.S. Patent 2,990,354

Originators: H.L. Anderson and H.S. Brown.

Status: Proposal, November 1942; patent issued; 1961.
Details: Variant of concept in Data Sheet No. 1. Graphite matrix has central

sphericaIFVOid filled with D,0. Al or U tubes imbedded in graphite pass

2
through D20° UF6 circulates through tubes. _
Cnde: 0312 12 31110 41 612 732 81X1l 941 LUY
14 42 733 81X12 |

No. 4 Liquid Hexafluoride Pile

Metallurgical Laboratory, University of Chicago

Reference: Unpublished report, 1943.

Originators: Staff members.

Status: Preliminary proposal, 1943,

Details: Thermal neutrons, steady state, burner. Fuel-coolant: liquid UF6°
Moderator-reflector: graphite. Fuel circulates through 170 Al tubes surrounded
by graphite to external heat exchanger. Secondary coolant: HZOa Moderator
would probably have to be cooled by subsidiary water cycle. Fraction of fuel
continuously withdrawn and put through evaporator for removing fission products.

Core requires 15 tons of UF, and 25 tons of graphite. Fuel temperature in core:

6
194°F; temperature rise in center tube: 108°F. Power: 390 MW(t).

Code: 0313 12 31110 44 612 711 8XXXX 921 104
No. 5 Proposed Hanford Circulated-Hexafluoride Thermal Pile

Metallurgical Laboratory, University of Chicago

Reference: Unpublished report, 1943.

Originators: Staff members.

Status: Proposal, 1943.
Details: Thermal neutrons, steady state, breeder. Fuel-coolant-fertile

material: natural U in liquid UF_, which circulates to external heat ex-
239 238 6

25

changer. Pu bred from U . Moderator: D,0. Reactor: vertical cylinder.

2
Fuel circulates through core in tubes of Al, Be, Mg, or U. Tubes immersed in
25 tons of DZO surrounded by graphite reflector, UF6 enters at 176°F and
leaves at 248°F. Operating pressure: 250 psia. Power: 390 MW(t).

Code: 0312 14 31110 41 612 732 8XXXX 921 104

No. 6 U233 Hexafluoride Breeder

Metallurgical Laboratory, University of Chicago

Reference: Unpublished report, 1944,

Originators: Staff members.
Status: Proposal, 1944, -
Details: Thermal neutrons, steady state, breeder. Fuel-coolant-moderator:

U233 in UF, dissolved in fluorocarbon; circulates to external heat exchanger.

6
Fertile material: Th reflector-breeding blanket., Fuel circulates through
tubes in cylindrical reactor. Temperature rise, fuel inlet to outlet: 90°F.
Power: 100 to 200 MW(t).

Code: 0312 18 31209 45 622 7X6 8XXXX 931 101
26

No. 7 Hex P-9 Pile (UF,-D,O Pile)
|8

2
Metallurgical Laboratory, University of Chicago

References: CE-1150; CE-1074; U.S. Patent 2,990,354, June 27, 1961.

Originator: H.L. Anderson.

Status: Preliminary design, 1944,

Details: Thermal neutrons, steady state, burner or breeder. Fuel-coolant:

686 tons liquid UF6 (465 tons U). U, probably highly enriched in U235 for

burner, probably natural for breeder. Bred Pu could be recycled as fuel.
Moderator: 63 tons D20. Fertile material: U238

fuel circulated by thermal syphon into reactor at bottom, through pipes in

in UFfi. Core arrangement:

core, and out at_top to external heat exchanger. Cold fluid returned to
bottom of core. Maximum temperature: 150°C, to avoid need for high pressure

to keep UF, liquid; minimum temperature: 75°C, to prevent solidification.

Pressure: 6150 psi, to prevent vaporization. Control: control rod and safety
rod of Cd or boron steel; high rate of change of density and high temperature
coefficient of expansion of UF6° Power: 600 MW(t). Specific power: 1300-
1600 kW/ton UF6 at AT of 75-130°C; 550-650 kW/ton UF at AT of 75-105°C.
Code: 0312 14 31110 41 612 711 81X11 9XX 104

0313 44 732 81X12

46 84689

No. 8 Homogeneous, Circulating Liquid UF,_ Fueled Pile

Clinton Laboratories

Reference: MonN-336.

Originators: Staff members.

Status: Preliminary proposal, 1947.

Details: Thermal neutrons, steady state, could be used for power production,

breeding, or producing high flux. Fuel-coolant-moderator: U235 in liquid UF6

dissolved in either liquid fluorocarbon or DF. Fertile material: ThF Fuel

solution circulates for continuous removal of fission products and foraheat
exchange. Reactor would operate at 100°C and, with DF moderator, 15 atm. Con-
tainment material would probably be Ni rather than Al or Mg, despite the loss
in breeding gain.

Code: 0311 17 31209 44 622 7X6 8XXXX 9XX 101

0312 18 31213
No. 9 Circulating Liquid UF, Pile
(o

< Clinton Laboratories

Reference: MonN-336.

Originators: Staff members.

Status: Preliminary concept, 1947.

Details: Thermal neutrons, steady state, could be used for power production,
breeding, or production of high flux. Fuel-coolant: U235 in liquidlUFG;.
could circulate t6 external heat exchanger. Moderator: Be. Reflector-
breeding blanket: 'I'hF4 as fine powder in Be cylinders in graphite bed. Con-
tainment materials: Be, Al, or Mg. Pressure: & atm. Specific power: .about
1 kW/kg UF,.

Code: 0311 15 31110 44 612 776 8XXXX 941 104

0312

27
28

No. 10 Gaseous UF, Fueled, Gas Cooled Power Pile
6—— . , .

Clinton Laboratories

Reference: MonN-336.

Originators: Staff members.

Status: Preliminary design, 1947.

Details: Thermal neutrons, steady state, could be used for power production,

U233 or U235

breeding, or production of high flux. Fuel: in gaseous UF

6'
Coolant: helium. Moderator: graphite. Reflector-breeding blanket: fine

powder of ThF, in Be cylinders in graphite bed. Bred fuel removed by slow ©.°

4

leaching out of PaF6 and UF6 by slow circulation of F2

structure: cylinder, 99 cm radius and 192 cm high. Fuel vol: 5900 liters,
with 15.8 kg U235. Fuel contained in porous Be fuel tubes, 1 cm diam., pro-

through the bed. Core

viding 75% voids; each porous element core enclosed in solid Be shell, 1.1 mm
thick, fihich closes pores on outside. Total fuel tubes: 5151; each contain
3.07 g U235. Graphite moderator either of rods at the center of triangular
lattice of fuel tubes or annular tubes around them. Helium circulates through

voids in core with AT of 750°F and an outlet temperature of 1250°F. Reactor

~designed to operate at 800°C and 10 atm. Since fission products become trapped

in fuel-element pores, they are removed from UF, without chemical processing.

6 235

Control: rods. Breeding ratio; slightly less than 1 with U""7, slightly more

with U233.  Specific power: 6000 kW/kg U233. Power: 96 MW(t).

Code: 0311 12 31716 44 662 776  8IXIX 941 106
0312 45
. No. 11 -Gaseous UF, Fueled, Gas Cooled Power Pile
Q

Clinton Laboratories

Reference: MonN-336.

Originators: Staff members.

Status: Preliminary concept, 1947. .
Details: Variant of concept’ in Data Sheet 'No. 10. Gas fuel circulates slowly
through porous Al fuel tubes (90% voids) outside reactor for continuous fission-
product removal that makes possible better neutron economy. Fuel tubes have
large pores that do not trap fission products as small pores in Be tube ‘do. Use
of Al, which allows tubes to be discarded rather than reprocessed, causes lower
power potential from reactor. Pressure: 10 atm. Specific power: 2500 kW/kg
U235. Power: 50 MW(t).

Code: 0311 12 31716 44 662 776 - 81X1X 941 106

0312 45

No. 12 Water-cooled, High Flux, UF, Fueled Pile
|9

Clinton Laboratories

Reference: MonN-336. : : .

Originators: Staff members.

Status: Conceptual design, 1947. -
Details: Thermal neutrons, steady state, could be used for power production,

233 or U235 as UF6° Coolant;

HZO' Moderator: H20 or Be. Reflector-breeding blanket: ThFA in blanket

similar to that in the concept in Data Sheet No. 10. Core structure: 240

breeding, or production of high flux. TFuel: U

liters of fuel, containing 3.25 kg U235, within porous Al rods encased in Be
tubes. Fuel elements mounted in hexagonal pattern; interstices filled with
solid Be, leaving 3-mm annulus around each fuel element for H,0 flow at 17
ft/sec. Containment: Be, Al, or Mg. Temperature: 260°C. Pressure: 50 atm.
Specific power: 10 MW/kg U235, Power 32 MW(t).

Code: 0311 13 31101 44 662 776 8XXXX 941 106

0312 15 45
30

No. 13 Circulating Gaseous UF, Fueled Pile
’ i O

Clinton Laboratories

Reference: MonN-336.

Originators: Staff members.

Status: Preliminary design, 1947. _

Details: Thermal neutrons, steady state, could be used for power production,
breeding, or production of high flux. Fuel-coolant: U235 in gaseous UF6’.
Moderator: Be. Reflector-breeding blanket: ThF4 in blanket similar to that

in concept in Data Sheet No. 10. Core structure: Be cylinder with longitudinal
holes through which fuel circulates. Containment: Be, Al, or Mg. Pressure:

20 atm.

Code: 0311 15 31710 b4 662 776 8XXXX 941 104
0312 '

No. 14 Homogeneous, Circulating Gaseous UF, Fueled Pile
0

Clinton Laboratories

Reference: MonN-336.

Originators: Staff members.

Status: Proposal, 1947,

Details: Thermal neutrons, steady state, could be used for power production,
breeding, or production of high flux. Fuel-coolant-moderator: U235 in gaseous
UF6 mixed with helium or CF, (moderating gas). Reflector-breeding blanket:
ThF4

circulates outside reactor for removal of fission products and heat exchange.

in blanket similar to that in the concept in Data Sheet No. 10. Fuel

Reactor vessel: sphere, 17 m in diameter. Pressure: 100 atm. Containment:
Be, Al, or Mg,
Code: 0311 18 31710 44 662 776 8XXXX 941 101

0312 19
31

No. 15. Gaseous UF, -Fueled Reactor .
L9

Reference: The Science and Engineering of Nuclear Power, I, pp. 303-6.

Originator: Clark Goodman.

Status: Proposal, 1947.

Details: Thermal neutrons, steady state, burner. Fuel-coolant-moderator:
enriched UF6 with F2 added to stabilize molecular UF6 and to act as addi-
tional moderator. Gas either circulates to external heat exchanger or remains
within reactor and is cooled by a coolant,such as liquid metal, passing
thrqugh coils. .

Code: 0313 1X 31710 44 662 711 8XXXX 9XX 101

17 31106 105

No. 16. Direct Expansion UF,-Fueled Reactor
6—

UKAEA

References: British Patent 799,575.

Originator: Peter Fortescue.

Status: Conceptual design, 1953; patent issued, 1958.

Details: Thermal neutrons, steady state, burner or breeder, with direct expan-
sion of fuel to turbine. Fuel-coolant: U235 in gaseous UF6° Moderator: Be
as molten BeF2. Core structure: moderator in cylindrical Ni calandria sub-
stantially filling Ni-lined cylindrical pressure vessel about 3 feet long.
Fuel flows through calandria tubes. Heat produced by critical mass causes
fuel to expand directly to turbine. Fuel fhen goes to external heat exchanger
and is recycled to core. Pressure: 20 atm. Control: as gas expands, reac-
tivity and heat decrease; Cd absorbers can be included in heat exchangers to
prevent criticality outside of core.

Code: 0312 15 31710 44 662 711 84699 9XX 104
0313 81XX2
32

No. 17 Direct Expansion UF, -Fueled Reactor
Lo}

Metallgesellschaft Aktiengesellschaft

References: United Kingdom Patent 855,155; French Patent 778,697; German
Patent 1,110,334, '

Originator: Hermann Clasen.

Status: Conceptual design, 1957; United Kingdom patent isgued, 1960.

Details: Thermal or fast neutrons, steady state, breeder or burner with direct

U235 233 -

expansion of fuel to turbine. Fuel-coolant: or U in gaseous UF

. : 6
Moderator: Be; reactor core and turbine to be made of Be as far as possible.
Reflector: graphite around core and turbine. Fuel contained in conical core,
which serves as turbine housing. Fission of U, initiated by Ra-Be source,

6 directly to rotor. Vapor 1s then recompressed and recycled to
core. If breeding is desired,'UZBSF6 would surround turbine. Pressure: 35

atm., high enough to begin chain reaction. Containment:; for thermal reactor,

expands UF

pure Be core surrounded by shielding of Monel alloy. For fast reactor, core

and turbine of Ni-Cu alloy. Control: decrease in pressure from expansion of

UF, . _
Cog_: 0112 15 31710 L 662 711 84699 921 104
0113 45 7X5 | |
0312 |
0313

No. 18 UFG-Fueled Reactor for Locomotive Propulsion

Baldwin-Lima-Hamilton Corp. and Denver & Rio Grande Western Railroad

References: Soviet J. At. Energy (English Transl.), 2, No. 5, p. 587 (1957);
Railway Age, 138, No. 14, p. 7; 141, No. 16, pp. 20-21.

Origiunators: 3taff membero.,

Status: Proposal, 1955,

Details: Thermal neutrons, pulsed, burner. Fuel: U235 in gaseous UF6° ‘Fuel
contained in two ends of cylinder having a piston. Recifirocating action by
piston compresses gas in each end alternately, causing criticality; piston
pushed to opposite end of cylinder by expansion of fissioning fuel. Each end
of cylinder surrounded by moderator and reflector.

Code: 0323 1X 3XXXX 44 662 711 8XXXX 921 109
No. 19 Gaseous UF, Reactor
w

Institute of Atomic Energy, Academy of Sciences, USSR

References: Proc. 2nd U.N. Int. Conf., 9, pp. 528-534; AECL-10l11.

Originators: I.K. Kikoin et al.

Status: Experimental operation, 1957.

Details: - Thermal neutrons, steady state, burner. Fuel-coolant: 90%-enriched
U in gaseous UF6. ClF3 could be added to make UF6 stable under irradiation.
Moderator: Be. Reflector: graphite. Core structure: fuel in cylindrical
core with 148 square Al channels, 40 x 40 cm, in square lattice under 1.3 atm.
Channels divided into sections connected to main header coupled to gas-pumping
system, allowing simultaneous filling of channels. Total vol: 31l4.liters.
Graphite reflector surrounding core is 50 cm thick on sides and 60 cm on top
and bottom. Criticality reached by heating fuel to 80-90°C, to cause a pro-
gressive increase in pressure. Containment: sealed protective vessel.
Asbestos in space between reflector and this vessel to prevent heat loss.
Control: one horizontal and &4 vertical channels for control and safety rods--
steel tubes filled with B,C. Manual control: 2 tubular steel rods filled

4

with BAC' Power: about 1.5 kW(t).

- Code: 0313 15 31110 44 662 711 81111 921 104
81211

33
34

No. 20 UF, Gas Phase Reactor
(o)

Burns and Roe, Inc.

Reference: Nucleonics, 16, No. 8, pp. 128-133, ‘Aug. 1958..

Qriginator: S Baron.

Status: Conceptual design, Aug. 1958.

Details: Thermal neutrons, steady state, converter. Fuel-coolant-fertile
material: 8%-enriched uranium in gaseous UF6 with BrF,3 added. Modefator:
graphite. Reflector: graphite. Core structure: core diameter 7.5 ft;
height 25 ft. Fuel flows inside Al double-tube-wall channels; intermediate
coolant (helium) in annulus between tube walls and in external heat exchanger.
Tubes set within graphite moderator blocks. Fuel, under 30 atm max. pressure,
enters core at 450°F and leaves at 900°F. Fuel flows by natural circulation;
core height of 25 ft necessary for maintenance of sufficient fuel velocity.
Since fuel is 8% enriched, some Pu forms, but only as incidental product.

Control: negative temperature coefficient. Power: 35 MW(e).
Code: 0311 12 31710 42 662 7X3 84699 921 104

No. 21 Gasceous-Fuel Fast Breeder Reactor

Worthington Corp.

Reference: Nucl. Power, 5, No. 47, pp. 125-126, March 1960..

Originators: F.G. Hammitt and David Aronson.

Status: Conceptual design, March 1960.

Details: Fast neutrons, steady state, breeder. Fuel: U235 in gaseous UF6.
Coolant: Na. Fuel and coolant flow through parallel tubes made of Ni alloy,
such as Inconel X. Containment: Inconel X. Radial breeding blanket sur-
rounds core. Control: negative temperature coefficient; pressure of UF6 in
tubes controlled. Power: 300 MW(t).

Code: 0112 11 31103 44 662 7XX 83699 9XX 109

84699
10.

12.

13.

14.

35

References

I.K. Kikoin, V.A. Dmitrievsky, Y.Y. Glazkov; I.S. Grigoriéfi, B.G. Bubovsky,

and S.V. Kersnovsky, Experimental Reactor With Gaseous Fissionable Sub-

stance (UF6), Proc. 2nd U.N. Int., Conf. on Peaceful Uses of Atomic Energy,
9, pp. 528-534, United Nations, N.Y., 1958.

D. Heymann and F.E.T. Kelling, Corrosion of Some Metals and Alloys in

Uranium Hexafluoride, Corrosion Technol., 5, pp. 148-151; 1958,

G. Langlois, Corrosion of Metallic Materials by Uranium Hexafluoride at
. T
High Temperatures, AEC-tr-6504, trans. of CEA-2385, Service d'Etude de

Separation des Isotopes de 1'Uranium, 1963.

J.A. Lane, Homogeneous Reactors and Their Development; in Fluid Fuel

Reactors, J.A. Lane, H.G. MacPherson, and Frank Maslan, eds., p. 23,

Addison-Wesley Publishing Co., Inc., Reading, Mass., 1958.

D.E. Hull, Possible Applications of UF, in Piles, MonN-336, Clinton

6
Laboratories, Aug. 5, 1947.

J.A. Wethington, Jr., Research Pertaining to a Uranium (VI) Fluoride-
Fluorocarbon Reactor. A Proposal to the United States Atomic Energy

Commission, Apr. 26, 1962.

H.L. Anderson and H.S. Brown, Liquid UF6 Plant for the Production of

Element 94, CN-362, Metallurgical Laboratory, University of Chicago,
Nov. 27, 1942,

H.L. Anderson and H.S. Brown, Nuclear Fission Chain Reacting System, U.S.

Patent No. 2,990,354, June 27, .1961. Filed Mar. 24, 1945,
Unpublished report, Metallurgical Laboratory, University of Chicago, 1943.
Ibid, 1944.

G.F. Quinn, Thermal Syphon for Hex P-9 Pile, CE-1150, Metallurgical
Laboratory, University of Chicago, Jan. 10, 1944. Decl., Dec. 13, 1953.

C.F. Quinn, Thermal Syphon in Homogeneous Pile, CE-1074, Metallurgical
Laboratory, University of Chicago, Dec. 2, 1943. Decl., Dec. 13, 1955,

D.E. Hull and F.T. Miles, Preliminary Report on a Hex Pile, MonN-240;
Clinton Laboratories, Jan. 22, 1947.

Clark Goodman, Construction of Nuclear Reactors, in The Science and

Engineering of Nuclear Power, I, Clark Goodman, ed., Addison-Wesley

Publishing Co., Inc., Reading, Mass., 2nd ed., 1952 (lst ed., 1947).
36

15.

16.

17.

18.

19.

20.

21.

22.

23.

E.H. Kerner, letter, J. Appl. Phys., 24, pp. 815-816, June 1953.

Peter Fortescue, Improvements In or Relating to Nuclear Power Plants,
United Kingdom Patent 799,575, Aug. 13, 1958. Filed Jan. 14, 1955,
application Qct. 17, 1953.

Hermann Clasen (Metallgesellschaft Aktiengesellschaft), Improvements In
or Relating to Nuclear Reactors, United Kingdom Patent 855,155, Nov. 30,
1960. Filed Oct. 23, 1958, application Nov. 8, 1957.

Atomic Locomotives, Soviet J. At., Energy (English Tramsl.), 2, No. 5,
p. 587, 1957

Ts Nuclear Power Practicable?, Railway Age, 141, No. 16, pp. 20-21, Oct. 8,
1956.

Atomic Locomotive Study Authorized, Ibid., 138, No. 14, p. 7, Apr..4, 1955,

Atomic Energy of Canada, Ltd., Survey of Soviet Reéactors (Status According
to Published Reports up to September 15, 1958), AECL-1011l. Translated
from Jaderna energie, 5, pp. 92-101, 1959.

S. Baron, Gaseous Fuel Reactor, Nucleonics, 16, No. 8, pp. 128-133, Aug.
1958.

F.G. Hammitt, A Gaseous-Fuel Fast Breeder Reactor, Nucl. Power, 5, No. 47,
pp. 125-126, Mar. 1960,

37

Chapter 3. -Reactors Fueled With Gases or Plasmas' .

Concepts in this chapter included those in which the fuel is a nonionized
gas or an ionized gas (plasma) at extremely high temperétures. Before oper-
ating conditions are reached, the fuel may be a solid or liquid. A concept
for such reactors was described by Shepherd and Cleaver in 1949.1 The advan-
tage of a gaseous fuel, its capability for attaining'temperatfires too high
for liquids or solids, is the basis for the suggested use of most of these
concepts for rocket propulsion. In rocket propulsion, the propellant gas would
act as coolant for the reactor. For interplanetary flights, the nuclear reac-
tion would have to raise the propellanp temperature by regenerative heating to
about 10,000°R. The name 'cavity reactor'" was suggested by Safonov2 for those
reactors in which a core of uniformly distributed gaseous fuel is surrounded
by a moderator-reflector of uniform density. They'were so named because the
flux distributions of dilute fuels approach the flat distribution of an empty

cavity and because of the gaseous fuel is at near-vacuum as it is used in the

system.
General

It -the simplest kind of a cavity reactor, the fuel and coolant are fed
separately into the core région, where they mix intimately, and are expelled
from the core. Separation is done externally. Because cost and weight must
be minimized in a rocket system, the fissionable material must be separated
Ifrom the coolant and conserved; yet, the coolant, which is also the rocket
propellant, must be able to pick up energy efficiently from the fuel for the
system as 4 whole to operafie effectively. .For this reason, several sophisti-
cated methods of achieving fuel-coolant éeparation have been considered. In
some, the two fluids are separated after mixing; in others, they are kept
separated in the core.

Configurations to keép the fuel and coolant separated while they both are
in the core region include (1) coaxial flow, (2) magnetohydrodynamic means,
and (3) magnetic fields. ‘Lhese methods-éf separation are discussed under the
concepts taken up in this chapter, 3

In many conceptg, the fuel is a plasma, which raises problefis of contain-
ment .,

There are two ways of restricting the interaction between high-temperature
gases and adjacent solid materials: (1) limit the interaction in time; or (2)
limit the interaction in space by eliminating all solid méterial in.the vicinity

of the hot gas and replacing it with an electromagnetic fiéld.
38

Nelson3

has suggested that, despite these problems, plasmas should be

considered because of their advantages. A plasma can be confined electro-

magnetically, separating it from the surrounding solid materials with’which

it would otherwise react;

it can be accelerated by electromagnetic means to

greater supersonic velocities than are obtainable with a nonionized gas ac-

celerated by means of fluid jets; and it can be separated from the nonionized

propellant.

The simplicity of the system relies on the fact that the ionized

fuel is confined by a field barrier, whereas the nonionized hydrogen propel-

lant diffuses through the field.

in plasma systems are given 1n Table 1.3

Table 1.

Limitations on the principal system variables

~

Limitations on Principal System Variables

Variable

Lower Limit

Upper Liwmil

Size

Temperature

Magnetic field
strenglh

Electrical field
strength

e
Propellant flow rate

Plasma rotational
velocity (homopolar
configuration)®

Criticality

Fuel ionization temperature

Plasma confinement
Coot of maximum tolerahle
fuel loas by diffusion

Rotation of plasma too
slow; thus instability and
intolerable axial diffusions

Flow channel across section
excessive (moderator too
heavy)

Plasma instability (maximum
permissible propellant
flow rate too slow)

Approaches diffusion proper-
ties of simple magnetic
bottle

Wt of moderator-reflector

Excessive fuel inventory

Excessive magnetic field
vol

Fabrication difficulties

Radiative heat transfer
to walls
Propellant ionization

Electric power require-
ments
Coil wt.

Supersonic-flow problems
Excessive voltage drop
across plasma

Excessive pressure

Helmholtz waves (propel-
lant swept through
nozzle)

Shock waves and boundary-
layer turbulence

Rotational kinetic energy
wasted in spinning
propellant

Nelson suggested confining plasma by either a simple magnetic bottle with

mirrors at each end or a homopolar device, which provides more reactor control.

*Fissioning plasma rotates by being electromagnetically pumped by crossed

electric and magnetic fields.

Centrifugal force associated with the rotation

tends to keep the plasma away from regions where leakage would most likely occur.
39

In reactors such as the vortex reactors, in which the propellant and fuel
mix intimately, the cooling mechanism is either regenerative heating or the
direct heating of the gaseous propellant by the slowing down of fission frag-
ments. In systems where the fuel and propellant do not mix, such as in the
magnetic containment of ionized fuel or coaxial flow, heat transfer from the
fuel to the propellant is principally by thermal radiatidn.

In those systems in which the primary energy-transfer mechanism is thermal
radiation, the radiation must be attenuated by the propellant gas before it can
reach the cavity walls. Also, at certain temperatures, the gases become trans-
parent to radiation. Hydrogen gas is transparent between 5000°R and 12,000°R.
Graphite dust can be used to 'seed" hydrogen for radiation absorption but it

sublimes at 6800°R.
Concepts

In Shepherd and Cleaver's 1949 concept for rocket propulsion,1 the fuel
and coolant are fed into a core area formed by the moderator-reflector. Here
they mix and the critical mass is reached. The propellant-coolant must be
heated to 3000-5000°K. The fuel material and moderator material are not speci-
fied, but the original form of fuel might be a powder, a liquid suspension of a
powder, a wire (extruded into the chamber) or a liquid compound of fissile
material. The coolant could be hydrogen, deuterium, helium, ammonia, or steam. -
Control might be possible by varying the amount of fuel fed to core. A specific
power of 100 MW per metric ton was sought. _

In 1955 Safonov2 advanced a design for a cavity reactor, with different

arrangements to fit different purposes. The gaseous fuel, of low density at

233 or U235, as well

the high operating temperature of the reactor, could be U
as plutonium. The fuel is in a region surrounded by a moderator-reflector of
heavy water, beryllium, or graphite. This moderator-reflector region could
contain fertile material for breeding and a thermal-absorbing material for
control. The coolant, an unspecified gas, is pumped around or through the

fuel. An inherent safety factor is stated to be the prompt neutron regenera-
tion time, which is as long or longer than that for solid-fuel thermal reactors.
The high neutron flux produced might make the reactor suitable for engineering
testing. Other modifications are: a gas- or air-cooled power reactor; zir-
conium tubes carrying liquid-metal coolant in the center and fissile material
at or near the outer surfaces; liquid metal to carry the fissile material; or
uranium hexafluoride fuel. The gas- or air-cooled and the UF6-fue1ed reactors
could be used to operate a turbine; the UF6-fue1ed reactor would operate by

direct expansion. In all, the fuel would be gaseous in reactor operation.
40

The direct conversion of mechanical energy produced in a pulsing plasma
to electrical energy is proposed in a 1957 concept by Colgate and Aamodt.4
The gaseous fuel, plutonium or uranium, is partially ionized at the tempera-
ture of operation. A magnetic field compresses the gas at one end of a
cylindrical graphite fuel container, which is blanketed by heavy water (the
coolant-moderator-reflector). The blanket is contained in aluminum or zir-
conium. As the gas is compressed, criticality occurs to release fission
energy, which drives the gas to the other end of the container. Here it is
again compressed and driven back by the fission energy. The oscillation of
the gas between the two ends causes the portion of the gas directly behind
the shock front to become highly ionized. As this plaswa, acting as a con-
ductor, moves through the magnetic field it induces an electrical current in
an external electrical circuit. The power is 500 MW(e).

A high-temperature (15,000°K) reactor with electromagnetic confinement

of fuel was described by Taylor in 1957.,5 The fuel, a plasma of U233, U235

>
or Pu239, is in a core surrounded by the moderator-reflector, heavy water or
beryllium. The coolant-propellant, hydrogen, passes through the core, where
it gains energy, and leaves the reactor. The fuel is retained in the core by
externally applied electromagnetic fields, which do not retain the nonionized
propellant.

A preliminary design for a reactor of high power, called a "fizzler",
was published by Bussard and bLelLauer in 1958,6 Designed to producc 5000 MW(t),
this reactor was intended for rocket propulsion. Fuel (UQJJ, Usz, or Pu239)
and coolant (rocket propellant) mix in a core region formed by the unspecified
moderator-reflector. Here criticality heats the fuel to above its vaporiza-
tion temperature. The authors conclude that at the operaliug pressure con-
sidered reasonable (1000 psi), greatly excessive amounts of fuel would be lost.

Two 1959 concepts by Grey7 were for rocket propulsion; few details were
given. 1In one, the "fizzler"'" reactor, the fuel is mixed in a solid with the
propellant, which is also the moderator. Removal of a portion of a cadmium
control rod causes criticality, which vaporizes the fuel. The other concept
is for a series of subcritical solid-fueled reactors. They are made tempo=-
rarily highly supercritical when propellant gas containing fissile material is
passed through them. The gas increases in temperature as it passes through

the series of reactors until it comes out of the nozzle at a very high tempera-

ture.

Meghreblian described two cavity reactors of similar design that were

intended for rocket propulsion. In both, two fuel zones were used, one of .
41

solid fuel and one of gaseous. 1In one,8’9 a central moderator matrix contains
the gaseous fuel and is surrounded by a solid fuel zone. In the other, . the
solid is in the central portion and the gaseous fuel in the moderator matrix
surrounds it. A reéflector-moderator surrounds the core in both. ' The coolant,
which is the rocket propellant, passes into the core, and picks up heat, first
from the solid-fuel region and then from the gaseous fuel. ©No details of
materials were specified.

The concept for a vortex reactor,l ) 7vproposed by Kerrebrock and
Meghreblian,ll’12 emphasized the separation of fuel and propellant, after
mixing, by the formation of a vortex. The fuel (gaseous uranium, plutonium,
or their compounds, in h&drogen) is contained as a jet-driven vortex in many
long thin tubes imbedded in moderator material (beryllium oxide or graphite).
After the fuel and coolant mix, the mixture spirals into the center of core,
is drawn off axially, and is discharged. Because of the radial pressure
gradient within the vortex, the heavier fuel molecules would be contained in a
steady-state concentration distribution in the vortex, while the lighter pro-
pellant gas would diffuse through it,l6 A core temperature of 10,000°R and a
power of 500 MW(t) were sought. 1In addition to the method described for at-
taining a vortex, magnetic fields, magnetic mirrors, or magnetohydrodynamics
(externally imposed electrical and magnetic fields) might be used.

Certain variables--tube diameter, mass flow rate per unit tube length,
jet injection velocity, and wall pressure--affect vortex strength.1 The
strength increases as tube diameter decreases and as mass flow rate incéreases,
and it increases with subsonic rather than sfipersonic injection. Because vor-
tices develop turbulent instabilities, particularly at the periphery, several
configurations designed to produce a laminar flow by stabilizing the shear
boundary layer on a concave wall have been considered. They are: (1) bleed-
off of the boundary layer through a uniformly porous wall, (2) injection of
heavy gas uniformly through a porous wall, (3) wall cooling, and (4) bleeding
ott some of the total flow axially at radial positions between the tube .center
and the wall so that the exit radial flow is held to an allowable rate, based
on diffusion considerations (bled-off flow would be recirculated).15

Three variants have been explored in somewhat more detail.

One variant includes 'a rotating porous wall through which the propellant
is introduced.15 Turbulence is reduced because the boundary layer on the outer

wall is effectively eliminated. However, to produce significant thrust levels,

many small tubes would still be required because mass flow per: unit of vortex
42

tube length remains limited by the diffusion process. There is a severe

mechanical problem in combining high temperature, high speed, and many tubes.
In another variant, excess mass flow, which has been jet-injected into

the system and which causes the vortex instabilities, is bled off and recir-

culated. The heavy mass could be helium + C or Freon-12 (CCL2F2).15

0 8716

The third variant is based on the same principle as the vortex reactor
except that, to reduce turbulence and to dissipate instabilities, several
vortices are generated in a single container in équare array, by means of fluid
injection from tubes located in the container. The injection and exit pattern
is designed so that adjacent vortices roll on one another, producing zero shear
at the interfaces. This eliminates a major sourc¢e of instabllity, turbulence
at the periphery of the vortices that are located in the interior of the matrix.
Also, since wall area per vortex decreases as the number of vortices inéteases,
the wall area per vortex approaches the area of a single injection tube as the
number of vortices becomes infinite. This greatly reduces the momentum removed
from the system by the action of shear forces, which is proportional to the
wall area involved.

In the Coaxial Flow Reactor of Weinstein and Ragsdale,ls’19

239

fully ionized gaseous Pu ", and the hydrogen coolant are fed into the core,

the fuel,

which is surrounded by a moderator of graphite, heavy water, or both. Here

criticality occurs. ‘the fuel is fed into the center of the core, and the

hydrogen enters around the periphery at a flow rate different from that ot the

fuel. Because of the differing axial velocities, the two streams do not mix.
They are exhausted from the core through a nozzle. The average reactor tempera-
ture is. about 10,000°R. - ‘Heat transfer from the fuel at this temperature is
primarily by radiation. The thermal energy must be atlenuated by the propcllant
to avoid overheating the walls (maximum temperature 5000°R). Because hydrogen
is transparent to radiation between 5000° and 12,000°R, ''seeding" with an ab-
sorber is necessary for radiative heat transfer. Solid particles, such as
graphite dust, might be adequate up to the sublimation point of graphite (6800°R).
A recent design by staff members at the Hanford Atomic Products Operation
is for a system to produce electrical power by a magnetohydrodynamic generator
and a secondary heat exchanger.20 Both would derive their power from a reactor
fueled with fissionable gas such as uranium hexafluoride. The gas flows in a
toroidal container at a density below that of criticality, except in the core
region. Here it is compressed to give criticality, and the gaseous fuel is

ionized. The plasma flows through a magnetohydrodynamic channel, whic¢h consists
of rails carrying current, and two large cryogenic magnets, which supply the
cross-current field. The plasma stream provides an emf to generate current
flow between the rails, The gas flows to a turbine and then to a heat ex-
changer to produce steam from the remaining usable heat. After purification,

the gas is returned to the system.
Status

A brief summary of a conference held at the Los Alamos Scientific
Laboratory in April 1964 indicates recent work on some gas- and plasma-
fueled reactors, although few details are given.

Ragsdale reported further work on the coaxial-flow reactor described
earlier in this chapter. Research was reported in heat transfer, hydro-
dynamics, and nucleonics. Larger flow area, plus higher propellant velocity,
is thought to give an economic ratio of propellant to fuel in the exhaust
gas. The ratio would be about 50.

In the "Glo-Plug" reactor, the gaseous fuel is contained within a double-
walled transparent tube. Hydrogen flowing between the walls cools the tube,
Heat transfer is by radiation through the tubes and coolant. The propellant,
seeded with material to make it absorbent, absorbs the radiation. Quartz was-
being considered as material for the tubes. X

Stumpf and Rosenweig, in reporting experiments on vortices, discussed
the possibility of combining vortex containment with other methods. For

example, fuel might be contained in some cells of a matrix of vortices and

propellant could flow through others.

43
44

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WAS INTENTIONALLY
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DATA SHEET

REACTORS FUELED WITH GASES OR PLASMAS

45
46

THIS PAGE
WAS INTENTIONALLY
LEFT BLANK
No. 1 Gaseous Reactor for Rocket Propulsion

Reference: J. Brit. Interplanet.-Soc., 8, No. 1, pp. 23-37,“Jan. 1949..
‘Originators: L.R. Shepherd and A.V. Cleaver. ' '

Status: Preliminary concepts, 1949,

Details: Thermal neutrons, stead& state, burner, for rocket propulsion.

Fuel: material not specified, but could be in initial form of: (1) powder;
(2) powder suspension in liquid; (3),wife extruded into chamber; or (4) liquid
compound of fissile material. Authors favor the last., Fuel would vaporize at

reactor operéting temperatures., Coolant: H2 or D helium; ammofiia, either

>

NH3 or N15D3; or steam, either‘HZO or D20° Méfieraior-reflector: external,
material unspecified. Fuel and coolant each fed into core area formed by
moderator-reflector, where they mix intimately and where critical mass is
formed. Reaction must heat coolant, which is rocket propellant, to 3000-
5000°K. Heated coolant is exhausted through nozzle. Control: varying amount
of fuel fed into the core. Specific power: 100 MW/metric ton.
Code: 0313 1X 31701 4x 66X 711 83799 - 921 107

31702 | - ,

31713 S

31715

31716

47 .
48

No. 2 Cavity Reactor

Rand Corporation

Reference: RM-1520.

Originator: George Safonov.

Status: Preliminary concept, 1955.

Details: Thermal, possibly epithermal neutrons, steady state, burner or breeder.
Fuel: U233 or U235 possibly in UF6; Pu239. Coolant: wunspecified gas. Moderator-
reflector: .D20, Be, or graphite. Fertile material could be contained in -
moderator-reflector without affecting criticality of core region. Core struc-
ture: low-density fuel contained in region surrounded by moderator-reflector.
Coolant pumped through or around fuel. Fuel density (presumably at operating
conditions) between 0.05 and 0.10 1lb/cu ft--less than % molecular density of
gases under standard conditions. ConlLrul: Llerwal-absorbing material in
moderator-reflector. Inherent safety factor is the prompt neutron regeneration
time, which is as long as or longer than that in solid-tuecl thermal reactors. A

6-ft diameter core in Be or graphite would require 12-14 kg U235 for criticality;

the same size in D20 would require 2 kg U235. Smaller amounts of Pu239 or U233
would be required. If neutrons in the epithermal range were used, smaller core
might be possible. The high neutron flux that would be produced might make the
reactor suitable for use in engineering testing. Author suggests the following
possibilities for reactor cénfigurations, with initial form of fuel (in opera-
tion, the fuel would be gaseous):

1. Gas- or air-cooled reactor operating at ''respectable specific power",
perhaps on a once-through basis for running a gas turbine.

Code: 0312 12 31714 44 662 7XX 81XX8 921 LO7

0313 14 31719 45 66X . 941
0212 15 46
0213

2. Zirconium tubes carrying fissile material on or near their outer surfaces.

Liquid-metal coolant would run through the center of the tube.
Code: 0312 12 31106 44 66X 7XX 81XX8 921 107

0313 14 45 | 941
0212 15 46 -
0213

3, Fissile material carried by a circulating l1iquid metal. This would have

self-stabilizing features of liquid-metal fuel.
Code: 0312 12 31106 44 66X 7XX 81XX8 921 107

0313 14 45 84689 941
0212 15 46
0213

4, Fuel might be U235F6’ which could expand directly for running a turbine or
a reciprocating engine.
Code: 0312 12 31710 44 662 7XX 81XX38 921 107

0313 14 941

0212 15

0213
No. 3 Fission-Plasma Reactor

Radiation Laboratory, University of California, Livermore, and LASL

Reference: Nucleonics, 15, No. 8, pp. 50-55, 'Aug. 1957..

Originators: S.A., Colgate and R.L. Aamodt.

Status: Preliminary concept, Aug. 1957.
Details: Thermal neutrons, pulsing, burner, with direct conversion to elec-
235
U o

trical energy for power production.' Fuel: T Pu239 in gaseous form,

or gaseous UF6' Coolant-moderator-reflector: DZO’ which blankets graphite
fuel container, to cool graphite and act as neutron moderator-reflector.
Gaseous fuel is uniformly contained in graphite and Al or Zr, which is sur-
rounded by D20 blénket, also contained in Al or Zr, and concrete shielding.
Magnetic field produced by Cu coils located in DZO blanket section compresses
fuel at one end of the container, causing criticality. Direct conversion is
accomplished by having ionized gas do work against the magfietic field. The
released fission energy creates a shock wave which drives the gas towards the
other end of the c0ntainef. As the gas oscillates, the portion directly be-
hind the shock front becomes highly ionized. This plasma acts as a conductor
moving in a magnetic field. The plasma, as it moves through the magnetic
field, induces a current in an external electrical circuit. This conversion
of mechanical energy to electrical is the basis for the generation of electri-
cal power--SOO MW(e). |
Code: 0323 14 31102 44 662 711 8XXXX 921 109

46 66X

49
50

No. 4 Plasma Core Reactor

Reference:  Aerojet-General Corp., unpublished report, 1957.

Originator: Lawnie Taylor.

Status: Preliminary concept, 1957.

Details: Thermal neutrons, steady state, burner for interplanetary rocket

propulsion. Fuel: U233, U235, or Pu239 plasma. Coolant: HZ' Moderator-
reflector: D20 or Be. Core structure: plasma-fuel core is surrounded by
moderator-reflector. H, coolant, which is rocket propellént, gains energy

2
by moving through core. Moderator-reflector material is core-wall. Wall

temperature is calculated to be 15,000°K or higher. Containmént: fuel con-
fined within core region by externélly applied electromagnetic fieids, by
either (1) simple magnetic bottle with mirrors at each end or (2) homopolar
device providing a strong electrostatic field for which moderator-reflector
is outer electrode and plasma is inner electrode. Magnetic field contains
ionized fuel but does not contain the nonionized coolant. Control: addition
of poison to coolant; variation of fuel and coolant consistency and injection
rates; variation of moderator consistency; variation of mirror separation and
ratio; variation of field intensity. Power density: 12-27 kW/cm3.

Code: 0313 14 34715 " 44 661 711 8159X 921 107

15 45 83699
46 83799
84667

84767
51

No. 5 Fizzler Reactor

Reference: Nuclear Rocket Propulsion, pp. 322-327..

Originators: Bussard and DeLauer (based on calculations of Safonov).

Status: Preliminary concept, 1958.
Details: Thermal neutrons, steady state, burner, for.rocket propulsion. Fuel:
U233, U?BS, or Pu239 initially in solid, liquid, -or gaseous form but uitimately
in gaseous form. Coolant: gas, not specified.  Moderator-reflector: not
specified. Fuel and coolant, which is rocket propellant, mix in core region
formed by moderator-reflector. Criticality raises fuel above vaporization
temperature. Fu€l density needs to be about 0.10 lb/cu ft. Power: 5000 MW(t).
Power density: 100 MW/cu ft. Drawback: at operating pressure of 1000 psi,
which authors consider reasonable, 20,000 1b éf fuel would be lost. To lose
only 300 1lb, which is calculated to be a maximum amount, pressure of 67,000 psi
would be needed; this is impractical. | ,
Code: 0313 1X 3X7XX 44 661 711 8XXXX 921 107

| 45 -

46

LY

No. 6 Fizzler Reactor for Rocket Propulsion

Reference: Astronautics, 4, pp. 23-25, 111-112, "Oct. 1959..

Originator: Jerry Grey.

SLalus: Preliminary concept, 1959.

Details: Thermal neutrons, steady state, burner. Fissile material mixed in

a solid ”grain” with moderating propellant. Control: Cd rod. Removal of a
portion of control rod causes criticality in fuel immediately adjacent, which
heats the fuel to vaporization temperature. Heat from this vaporization
travels up the fuel axis, reducing the neutron-absorption cross section of

the control rod enough to allow criticality, temperature rise, and vaporization
of all of the fuel,.

Code: 0313 1X 3X7XX 4X 66X 711 81212 9XX 109
52

No. 7 Gas-Solid Fueled Reactors, Series for Rocket Propulsion

Reference: Astronautics, 4, pp. 23-25, 111-112; Oct. 1939..

Originator: Jerry Grey.

Status: Preliminary concept, 1959. ‘

Details: Pulsed burner. A series of suberitical '"conventional' (solid-fueled)
reactors are temporarily rendered highly supercritical when a slug of propel-
lant gas containing some gaseous fissionable materiél_passes through them. Gas
is heated to increasingly high temperatures as it passes fhrough each succeeding
reactor, finally coming out of nozzle at very high temperature.

Code: 0X23 1X 3XXXX 4X 66X 711 8XXXX 9XX 109

No. 8 Cavity Reactor’

Jet Propulsion Laboratory

References: JPL-TR 32-42; JPL-TR 32-94.
Originator: R.V. Meghreblian.

Status: Preliminary concept, 1961; work continuing.

Details: Thermal neutrons, steady state, burner, for rocket propulsion.
Central moderator métrix contains gaseous fuel. This is surrounded by solid-
fuel region. Reflector-moderator surrounds core. Coolant, which is rocket
propellant, is fed into core tangentially, first picking up heat (regenerative
cooling) from temperature-limited solid-fuel region, then from gaseous-fuel
region, which is not temperature-limited. Coolant mixes with gaseous fuel and
then is exhausted from reactor. No details of materials given,

Code: 0313 1X 317XX 4X  5XXX 66X 711 8XXXX 921 109
No. 9 Gaseous Propulsion Reactor

Jet Propulsion Laboratory

Reference: . Nucleonics, 19, No. 4, pp. 95-99, {Apr. 1961..

Originator: R.V. Meghreblian.

Status: Preliminary concept, 1961,

Details: Similar to reactor described in Data Sheet No. 8. However, solid
fuel is located in the center of the core and is surroundéd by a moderator
matrix, which contains gaseous fuel. This, in turn, is surroundéd by the
moderator-reflector. The coolant, fed in tangentially, first picks up heat
from the solid-fuel region, then from the gaseous-fuel region. No matefials
indicated. ‘

Code: 0313 1X 317XX 4X 5XXX 66X 711 XXX - 921 109

No. 10 Vortex Reactor

References: AD-265961; CF-57-11-3; J. Aerospace Sci., 28, No. 9, pp. 710-
724, (Sept. 1961 ; NASA-TN-D-288; ORNL-2837; N-2865a; NP-10270.

Originétors: J.L. Kerrebrock and R.V. Meghreblian.

Status: Concept, 1958; work continuing..
Details: Thermal neutrons, steady state, burner, for rocket propulsion. Fuel:
U, Pu, or their compounds, in H,. Fuel either gas or a gas-carrying solid.

2

Coolant: CHA’ NH3, or H Moderator: BeO or graphite. Reflector: Be or

D20° Fuel contained as i jet-driven vortex in many long, thin, discrete tubes
imbedded in moderator material. Vortex can also be generated by: (1) exter-
nally imposed electrical and magnetic fields; (2) rotating magnetic field--a
radial electric field between a pair of cylindrical electrodes combined with an
axiéi magnetic field; or (3) magnetic mirror in a cylindrical configuration.
Fuel and coolant, which is also rocket propellant, mix. As mixture spirals into
center it is drawn off axially and discharged through one end. 1In the vortex, a
strong radial pressure gradient exists. With such a gradient, the heavy fis-
sionable gas is contained in a steady-state concentration distribution in the
vortex and the lighter propellant gas diffuses through it. Reactor is right
cylinder of equal height and diameter. Gas exit pressure might be 100 atm.,
core temperaghre 10,000°R. Power: 500 MW(t).
Code: 0313 12 3X707 44 661 711 8XXXX 921 104

15 3X715 46 663 107

3X713
54

No. 11 Coaxial Flow Reactor

National Aeronautics and Space Administration

References: TID-7653 (Pt.l), pp. 110-114; ARS Paper No. 1518-60, 1960.

Originators: H. Weinstein and R.G. Ragsdale,

Status: Concept, 1960; work continuing. A .
Details: Thermal neutrons, steady state, burner, for rocket propulsion. Fuel:
fully ionized gaseous Pu239. Coolant: H, seeded with something like graphite

2

dust. Moderator-reflector: graphite or D,0 as external reflector-moderator,

2
or a two-region moderator with graphite inside and DZO outside, Core struc-
ture: criticality takes place in cavity (LU ft long, 10 fL diaw.) formed by
external moderator-reflector. Fuel is fed into center of core; fuel region

about 10 ft diam. Coolant, which is rocket propellant, is fed into core around

'periphery at flow rate different from flow rate of fuel. Differing axial

velocities preveht two fluids from mixing. Coolant and a small portion of the
fuel are exhausted from core region through nozzle. Control: rotating-drum
control rods. One study using both graphite and D20 as moderator-reflector
has been based on the following parameters: reactor overall. is 16.6 ft long
and 16.6 ftlin diameter, cavity: 10 ft long, 10 ft in diameter; moderator-
reflector; 3.3 ft thick. Fuel velocity: 0.2 ft/sec. Coolant velocity:
17 ft/sec. Temperatures: fuel, 20,000°R; hydrogen, 10,000°R; graphite,
5,000°R; D,0, 70°R., Since hydrogen at these Lewperatures is transparent to
radiatiofi,“it must be ''seeded" with absorbing material for heat transfer,
Graphite dust might be satisfactory up to its sublimation point (6800°R).
Pressure: 2200 psia with fully ionized fuel,.
Code: 0313 12 34715 46 661 711 8144 921 107

14 | 109
55

No. 12 Homogeneous Gas Phase Magnetohydrodynamic Nuclear Reactor

General Electric Co., Hanford

Reference: Unpublished report, 1965.

Originators: Staff members.

Status: Concept, 1965.

Details: Steady state, burner. Fuel: gas, é.g. UF6. Gaseous fuel flows in
toroidal container in subcritical density except in core region, where it is
‘compressed to cfiticality.' Nuclear reactions and heat cause ionization of
fuel. 1Ionized stream passes through magnetohydrodynamic'channel composed of
current-carrying rails and 2 cryogenic magnets that provide a cross-current
field. 1Ionized gas stream provides the electromotive force to generate the
current flow between the rails. The gas could then expand directly to a tur-
bine. Gas then proceeds through heat exchanger for steam production and to
unit for gas separation and pufification. Fission products and wastes are
discarded, and purified gas plus enough‘new fuel to keep consistent level

circulates again to compressor. , :
Code: 0X13 1X 3X710 4X 662 711 84699 921 109
56

O

10.

11.

12.

13.

References -

L.R. Shepherd and A.V. Cleaver, The Atomic Rocket, J. Brit. Interplanet.
Soc., 8, No. 1, pp. 23-37, Jan. 1949. i

George Safonov, The Criticality and Some Potentialities of '"Cavity
Reactors', RM-1520, The Rand Corporation, July 17, 1955. Decl., Oct. 12,
1959,

S.T. Nelson, The Plasma Core Reactor, TDR-594(1555—01)TN-1 (AD-258979),
Aerospace Corp., May 10, 1961.

S.A. Colgate and R.L. AamodL, Plasma Reactor Promises Direct Electtic

Power, Nucleonics, 15, No. 8, pp. 50-55, Aug. 1957..

Lawnie Taylor, unpublished report, Aerojet-Ceneral Corp., 1957.

R.W. Bussard and R.D. DeLauer, Nuclear Rocket Propulsion, pp. 322-327,
McGraw-Hill Book Co., Inc., N.Y., 1958.

Jerry Grey, Gaseous-Core Nuclear Reactors, Astrofiautics, 4, pp. 23-25,

111-112, Oct. 1959.

R.V. Meghrehlian, Gaseous Fission Reactors for Spacecraft Propulsion,
JPL-TR-32-42, Jet Propulsion Laboratory, California Institute of Tech-
nelogy, Tuly 6, 1960.

R.V. Meghreblian, Gaseous Fission Reactors for Booster Propulsion, JPL-
TR-32-94, Jet Propulsion Laboratory, California Institute o[ Technology,
Mar. 31, 1961. '

R.V. Meghreblian, Gaseous Propulsion Reactors, Nucleonics, 19, No. 4,

pp. 95-99, Apr. 1961.

J.L. Kerrebrock and R.V. Meghreblian, An Analysis of Vortex Tubes for
Combined as-Phase Fisgion Heating and Separation of the Fissionable

Material, CF-57-11-3, ORNL,:Apr:' 11, 1958.

J.L. Kerrebrock and R.V. Meghreblian, Vortex Containment for the Gaseous-

Fission Rocket, J. Aerospace Sc¢i., 28, No. 9, pp. 710-724, Sept. 1961.

M.L. Rosenzweig, Advanced Propulsion Studies. Summary of Research in the
Field of Advanced Nuclear Propulsion. Semiannual Technical Report,

January 1-June 30, 1961, AD-265961, Aerospace Corp.
14,

15.

16.

17.

18.

19.

20.

21.

57

R.G. Ragsdale, NASA Research on the Hydrodynamics of the Gaseous Vortex
Reactor, NASA-TN-D-288, National Aeronautics and Space Administration,

Sept. 1960.

J.J. Keyes, Jr., and R.E. Dial, An Experimental Study of Vortex Flow for
Application to Gas-Phase Fission Heating, ORNL-2837, ORNL, June 13, 1960,
Decl., Mar. 8, 196l. A

M.L. Rosenzweig, The Vortex Matrix Approach to Gaseous Nuclear Propulsion,

N-2865a, Aerospace Corporation, 1961.

M.L. Rosenzweig, W.S. Lewellen, and J.L. Kerrebrock, The Feasibility of
Turbulent Vortex Containment in the Gaseous Fission Rocket, NP-10270,

Space Technology Laboratories, Inc., Oct. 17, 1960.

H. Weinstein and R.G. Ragsdale, A Coaxial Flow Reactor--A Gasebus

Nuclear-Rocket Concept, Paper No. 1518-60, presented at the ARS 15th

" Annual Meeting, Washington, D.C., Dec. 5-8, 1960.

rd

R.E. Hyland, Two-Dimensional Diffusion Calculations on Co-Axial Cavity
Reactors, pp. 103-109; R.G. Ragsdale and F.E. Rom, NASA Research on the

Coaxial Flow Gaseous NuclearRocket, pp. 110-114 in Proceedings of Nuclear

Propulsion Conference, Naval Postgraduate School, August 15-17, 1962,
Monterey, California, TID-7653 (Pt.l), USAEC, July 1963.

Unpublished report, Hanford Atomic Products Operation, General Electric

Co., 1965,

Nuclear News, 7, No. 11, p. 41, Nov. 1964.