ORNL-TM-3428.txt

 

ORNL-TM- 3428

Contract No. W-Th4O5-eng-26

REACTOR DIVISION

ESTIMATED COST OF ADDING A THIRD SALT-CIRCULATING SYSTEM FOR
CONTROLLING TRITIUM MIGRATION IN THE 1000-MW(e) MSBR

Roy C. Robertson

JULY 1971

 

This report was prepared as an account of work
sponsored by the United Stafes Goverament, Neither
the United States nor the United States Atomic Energy
Commission, nor any of their employees, nor any of
their contractors, subcontractors, or their employees,
makes any warranty, express or implied, or assumes any
legal liability or responsibility for the accuracy, com-
pleteness or usefulness of any information, apparatus,
product or process disclosed, or represents that its use
would not infringe privately owned rights.

 

 

OAX RIDGE NATIONAT, LABORATORY
Oak Ridge, Tennessee
Operated by
UNION CARBIDE CORPORATION
for the
U.S. ATOMIC ENERGY COMMISSION

. h'-, Care Lo o onld et

&MK

;wfnap TTEAAY o RTETTL S g e g N e ""V"'-""'}
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Abstract

Summary and Conclusions
1. Introduction

Descrigtion of MSBER Modified with Third Loops

2.

3.

)-"0

5.

Table 1.

Table 2.

Table 3.

Table L,

Table 5.

Table 6.

Table 7.

Table 8.

Table 9.

Table 10.
Table 11.
Table 12.
Table 13.
Table 1k,
Fig. 1.

Heat Transfer Equipment
Salt-Circulating Pumps
Salt Inventory Costs

iii

CONTENTS

LIST OF TABLES

Summary of Cost Items Affected by Modifying
MSBR Reference Design to Include Third

Salt-Circulating LoOps ==---re=mm—mmmcmcmmemamem
Selected Properties of the MSBR Molten Salts ---
Material Costs Used in Estimates =--cececccceaa--
Primary Heat Exchangers -—-=-eeecemecccmcmcecmene-
Secondary Heat Exchangers —--------eeamccccaeao-
Steam Generators —--eece-mcm e se e mmemam—— -
Steam Reheaters —=--ceecmocm e

Reheat Steam Preheaters ---ecemcmemccccccmcccecea

Revigsed Reference Design Costs for Heat

Transfer Equipment, in $1000 --c-moommmmmcmaoo

Estimated Direct Cost of Installed Heat
Transfer BEquipment per Square Foot of Surface

Estimated Design Data and Allowances for

Installed Costs of Salt-Circulating Pumps ----

Estimated Pumping Power Requirements and Worth
of Improved Efficiency of Modified MSBR Cycle

Estimated Salt Inventory Costs e--e-mmmeceaaa--

Estimated Volume of LiF-BeFy Salt in Secondary

System of Modified MSBR =--ve-emmcmcememeacaem

LIST OF FIGURES

Schematic Flowsheet of 1000-MW(e) MSBR Power

Station as Meodified with Addition of Third

Loops to Trap 3H —--memmmmmm oo

TS o A TN T MM D WD R N D WE GE MR MR W WY W e TR W M e W e e

e e e o e e e e S e el D i e i S R G R G ED G DR W ME e SN R M e e e

- -

A mr En am T o W e e U me ST S S e N D GE EE Em e

e R I N G EE MR I e W M W R W R W R R ger W e e mm o e

O N e e w e R S e e e A e g Ee e e e e e R e M R e S W A

e A T SER S M M M M M S M AR MY M R W N S R G REE NN GE B M W R W MR S e ee S e e s b e s WS el W G W S ol me WS e

- mm o o -

— g —— s e

- — - —

Page

O ~1 W1 1o

21
2k

11
12
13
15
LT
19
20

21

22

23

23
25

26
iv

LIST OF FIGURES (Contd.)
Page
Fig. 2. MSER Reactor Cell Layout Indicating Possible

Location for Secondary Heat Exchanger
and Pump =--eececemmcmcmeccc e e 10
ESTIMATED COST OF ADDING A THIRD SALT-CIRCULATING SYSTEM FOR
CONTROLLING TRITTIUM MIGRATION IN THE 1000-MW(e) MSBER

 

Roy C. Robertson

ABSTRACT

Controlling tritium migration to the steam system of
the 1000-MW(e) reference design MSER power station by
interposing a KNQOz-NallO;-NalNOs; salt-circulating system to
chemically trap the tritium would add about $13 million
to the total of $206 million now estimated as the cost of
the reference plant if Hastelloy N is used to contain the
"LiF-BeF, salt employed to transport heat from the fuel
salt to the nitrate-nitrite salt, and about $10 million
if Incoloy could be used. The major expenses associated
with the modification are the costs of the additional
heat exchangers ($9 million), the additional pumps ($5
million), and the "LiF-BeFz inventory ($4.8 million).
Some of the expense is offset by elimination of some
equipment from the feedwater system ($2 million), through
use of less expensive materials in the gteam generators
and reheaters (about $2 million), and through an improved
thermal efficiency of the plant (worth about $1 million).
In addition to acting as an effective tritium trap the
third circulating system would make accidental mixing of
the fuel and secondary salts of less consequence and
would simplify startup and operation of the MSBR. A
simplified flowsheet for the modified plant, a cell lay-
out showing location of the new equipment, physical prop-
erties of the fluids, design data and cost estimates for
the new and modified equipment are presented.

KEY WORDS - *MSER + *tritium + *capital cost + conceptual
design + loop + cooclants + heat exchangers + pumps +
power costs + fuel-cycle costs + steam system.
SUMMARY AND CONCLUSIONS

Controlling tritium migration to the steam system of the 1000-MW(e)
reference design MSER power station by interposing salt-circulating loops
to chemically trap the tritium would add 4 to 6% to the total plant cost.
The net increase in capital cost of the plant, including indirect costs,
is about $13 million if Hastelloy N is used to contain the 7LiF-BeFg
salt employed as the heat transport fluid in the secondary system, and
about $10 million if Incoloy could be used. These increases would apply
to a cost for the reference design plant now estimated at about $206
million (based on early 1970 costs). Addition of the loops would in-
crease the power production costs by 0.2-0.3 mills/kWhr, making the
total cost about 5.5 mills/kWhr.

As shown in the cost summary, Table 1, the major portion of the
cost of modifying the design is due to the additional heat exchangers
and pumps required, and to the relatively high cost of the 7Li-bearing
secondary salt. There were also increases in the cost of the primary
heat exchangers and in the fuel-salt inventory. However, the added
third loops use a nitrate-nitrite heat transport salt which permits
savings in the material costs in the steam generators and reheaters.

Use of this salt also permits reductions in the feedwater and cold re-
heat steam temperatures, and through changes in the steam system flow-
sheet and the auxiliary electric load, produces a reduction of costs
equivalent to a plant investment of about $800,000. Credit for these
savings was taken in the net costs mentioned above.

In addition to serving as an effective tritium trap, the third
loops offer other important advantages over the reference design. These
are features which, in general, could not have cost credits assigned.
For example, the similarity of the fuel and secondary salts makes mixing
due to leaks in the primary heat exchanger of far less consequence than |
in the reference design. Startup and operation of the MSER would be
simplified because of changes that could be made in the steam system
flowsheet.
Table 1. Summary of Cost Items Affected by Modifying MSBR Reference
Design to Include Third Salt-Circulating Loops

(in $1000)

 

Rev. Reference
Design MSER

Modified MSBR
with Third Loops

 

A. With Hastelloy N secondary system

 

Revised equipment:
Primary heat exchangers (see Table 4)  $8,660

Steam generators (see Table 6) 7,230
Steam reheaters (see Table 7) 1,565
Coolant salt pumps (see Table 11) 4,400
Coolant salt pilping allowance 1,900
Coolant salt drain tank 800
Coolant salt inventory cost 500
Auxiliary boller allowance 3,000

New equipment:
Secondary heat exchanger (see Table 5)
Secondary pumps {see Table 11)
Secondary salt drain tank
Secondary system piping allowance

Accessory electrical for secondary
system

Eliminated equipment:
Reheat steam preheaters (see Table 8) 1,056

Pressure-booster pumps 650
Mixing chambers 80
Total direct construction cost, in $1000 $29,841

Difference in direct construction costs

Difference in total cost with added
indirect costs of 33%

7LiF-BeF, inventory cost (see Tables 13
and 14

Credit for resale value of 7LiF-BeFy

Credit for improved plant efficiency
(see Table 12)

Net estimated capital cost of adding third
loops

$7,190

 

$9,563

4,800

—239

81T

$13, 300

$ 9,880
6,192
1,216
2,750
1,500

800
135
2,500

6,883
3,800
800

375
200

$37,031

(continued)
Table 1 (continued)

 

Rev. Reference Modified MSER
Design MSBR with Third Loops

 

Changes in power production cost: mills/kWhr
Net cost of adding third loops, at 13.7% FC + 0.187
LiF-BeFy inventory, at 13.2% FC + 0.090
Credit for resale LiF-BeFy, at 13.2% FC — 0.005
Credit for improved efficiency, at 13.7% FC — 0.015
Increase in fuel-cycle cost + 0.013

0.27 mills/kWhr

+

Net increase in cost of power

B. With Incoloy secondary system

All items in modified MSBR not affected by
use of Incoloy rather than Hastelloy N in $ 19,8093
secondary circulating loop, from Part A, above.

 

Cost of items in which Incoloy is substituted
for Hastelloy N:

Primary heat exchangers,(see Table k) 8,661
Secondary salt piping allowance 225
Secondary heat exchangers (see Table 5) 5,879
$ 34,658
Cost of revised reference design, from Part A -29,841
Difference in direct construction costs $ L,817
Difference in total cost with indirect $ 6,407
costs of 33% added
7LiF-BeFy inventory cost (see Tables 13 and 1k) 4, 800
Credit for resale value of 7LiF-BeF, ~239
Credit for improved plant efficiency (see Table 12) —317
Net estimated cost of adding third loops $ 10,200
Changes 1n power production cost. mills/kWhr
Net cost adding third loops, at 13.7% FC + 0.125
LiF-BeFy inventory, at 13.2% FC + 0.090
Credit for resale LiF-BeFy, at 13.2% ¥C - 0.005
Credit for improved efficiency, at 13.7% FC - 0.015
Increase in fuel-cycle cost + 0.013
Net increase in cost of power. + 0.21 mills/kWhr

 
1. INTRODUCTION

Tritium formed in the MSBR fuel salt must be prevented from reaching
the steam system. The problem is difficult because of the relative ease
with which hydrogen diffuses through most metals at MSER cperating tem-
peratures. Studies are being made at ORNL of several different methods
of tritium control; of these, the introduction of a third salt-circulating
system to chemically trap the tritium between the secondary salt and the
steam system is the only one well within present technology and, on the
basis of present knowledge, offers assured confinement of the tritium.

It is possibly one of the most expensive of the control methods being con-
gidered, however, and raises the question as to whether its use would add
prohibitively to the cost of a molten-salt reactor power station.

This study evaluates the various cost factors involved in adding
the third salt-circulating system to the 1000-MW(e) MSBER reference design
described in ORNL-4541.%* The cost estimating methods follows those used
in that report. The costs of modifying the reference design include the
capital cost of the extra equipment, the salt inventories, and also reflect
the cost effects of the new designs for the heat transfer equipment made
necessary by the use of heat transfer fluids different from those used in
the reference concept. (The calculations for the new and modified heat
exchangers were made by C. E. Bettis et al., using essentially the same
computer programs s were used in the reference design.) The cost egti-
mates also take credit for the equipment not needed in the feedwater
system of the modified plant and for the improved thermal efficiency of
the station, as explained below.

The reference MSER design uses circulating sodium fluoroborate,
Nal'-NaBF,, to transport healt to the steam generators and reheaters, whereas
the modified design uses a nitrate-nitrite heat transfer salt, KNOz-NaNOs-
NaNOs (known commercially as "Hitec"), to heat the steam equipment. This

has five important advantages: (1) any hydrogen diffusing into the salt

 

1Roy C. Robertson et al., Conceptual Design of a Single-Fluid Molten-
Salt Breeder Reactor, ORNL-4541 (May 1971).

 

 

 
would combine with the oxygen and subsequently be drawn off as steam and
collected, forming an effective tritium trap; (2) the salt is not corro-
sive to less expensive materials of construction, allowing Incoloy 800,
or a similar material, to be substituted for the Hastelloy N used in the
reference design; (3) its low melting temperature of 288°F permits use of
conventional feedwater and cold reheat temperatures in the steam systenm
and eliminates the need for the reheat steam preheaters, the pressure-
booster pumps and mixing chambers used in the reference design; (L)
startup of the system is simplified and the auxiliary boiler probably
does not need to be a supercritical-pressure unit as in the reference
plant; and (5) the selt has a low cost of only about 15 cents/1b. The
salt does not react exothermically with water and it has good flow and
heat transfer properties.

The modified design would use a "LiF-BeFg salt to transport heat
from the fuel salt to the nitrate-nitrite salt. With the exception of
the uranium and thorium components, this salt is the same as the fuel
salt, and thus a leak in the primary heat exchanger would be of far less
consequence than in the reference design where dissimilar salts would mix.
The 7LiF-EeFa is not corrosive to materials less expensive than Hastelloy
N, provided that no moisture is present. One cost estimate in this study
has been made using Hastelloy N for the secondary system and another
using Incoloy. Due to the lithium-7 content, the cost of the salt is
relatively high -- about $12/lb. Its resale value at the end of the
30-year plant life has been taken into account, although the effect is
not great.

The reference MSER design consists of a single reactor supplying
heat to four primary circulating loops, each containing a salt-circulating
pump and a heat exchanger. The coolant-salt system contains four loops,
with each containing a salt-circulating pump, four steam generators and
two reheaters. This arrangement was not altered in the modified design,
although there was some adjustment of the temperatures. The interposed
salt-circulating system would consist of four loops, each containing a
circulating pump and a heat exchanger. The following terminology has been

adopted.
Fuel salt to 7"LiF-BeF; heat exchanger -~ Primary heat exchanger
Li¥-BeF; to KNO4-NaNO,-NaNOs exchanger -~ Secondary heat exchanger
KNC5-NaNQg -NaNOa to steam exchangers -~ Steam generator or

steam reheater
Fuel-salt circulating pump -~ Primary pump
LiF-BeFy; circulating pump -~ Secondary pump
KNOg ~-NaNOg -NaNOs circulating pump -~ Tertiary pump

This study is primarily concerned with evaluating the cost effects
of adding the third salt-circulating loops. The concept was not carried
further than to indicate general feasibility and to provide a basis for
cost estimates. No effort was made toward cptimization.

In comparing the cost of the MSER modified with the third loops
to the reference design cost estimates, it was necessary to make some re-
visions to the latter as reported in ORNL-4541. The heat transfer equip-
ment design data have undergone two relatively recent revisions. The
first was made in time to be tabulated with the design data in the latest
disgtributed draft of the report, but, because of the extensive changes
required and the fact that at the time the influence on costs appeared
to be small, the cost estimates were not adjusted accordingly. The
second revision, which applied only to the primary heat exchanger, was
made Jjust in time for the data to be changed before the report was
printed, but, again, the cost estimates could not be revised. All of
the revisions tended to increase costs, however, and when the cost esti-
mates were revised in this study it was found that in aggregate they
amounted to about $4# million, including the indirect charges. The total
.capital cost of the reference design MSER is thus about $206 million
rather than the $202 million given in ORNL-4541. Both amounts are based
on the early 1970 value of the dollar.

2. DESCRIPTION OF MSER MODIFIED WITH THIRD LOOPS

A simplified flowsheet for the 1000-MW(e) MSER station as modified
to include the third salt-circulating loops is shown in Fig. 1. It can
be noted that the temperatures have been adjusted from those used in the

reference design and that there were corresponding changes in the mass
ORNL-DWG T1-T322

Primary Secondary Tertiary
Pump Pump Pump
14,255 gpm 13,380 gpm 17,370 gmm

1000C°F

] 0 0 e T

| 1000°F
-
dD_j ‘ I——S’team
{ 1200°F l

 

 

 

 

 

 

  
    

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

1100°F N
A © Steam
1300°F Primary HX Secondary HX Gen. Reheater
T50°F
<
Reactor 950°F '?f’ 4
25 MW t) . 1.)4'.7 x 10 lb/h]i// * l —isooF
Heat 1050°F [________,__J —_

K -NalNO -NaNO

Losses TLiF-BeF, N05 a¥o 3 | Steam

Fuel Salt — 2 \_ __ __ __ 551°F
23,4 x 100 1b/hr 13.3 x 10° 1b/hr Feedwater

All flow rates are for each of four loops

Fig. 1. GSchematic Flowsheet of 1000-MW({e) MSBR Power Station
as Modified with Addition of Third Loops to Trap SH.
flow rates of the salts. The flow quantities shown on the flowsheet are
for each of the four circulating loops.
The secondary heat exchangers and the associated LiF-BeFz pumps

can be arranged in the reactor cell without changing the dimensions of
the contaimment structure, as indicated in Fig. 2. The layout provides
relatively short piping between the primary and secondary heat exchangers
to keep the lithium-7 inventory low. No major changes would be required
in the salt piping to the steam generators and reheaters. On this basis,
the cost estimates for the modified system do not include any expenses

for modification of the building or cell structure.

3. HEAT TRANSFER EQUIPMENT

The physical properties of interest for the fuel and heat-transport
salts are given in Table 2. (Sodium fluoroborate has been included for
comparison, although not used in the modified MSBR system. )

The costs of the heat transfer equipment were based on the estimated
weights of the various shapes of materials used in fabrication, and on a
unit price which reflects the costs of fabrication, inspection, trans-
portation, and installation ready for use. The total installed costs of
Hastelloy N and Incoloy 800, as used in this study, are listed in Table
3. As in the reference design, the base prices of materials can be deter-
mined with relatively good certainty, but the additions to provide the
total installed cost greatly overshadow the basic material cost in impor-
tance and also involve considerable intuitive judgment. As a rough check
on the reasonableness of the cost estimates, the costs per square foot of

heat transfer surface are compared in Table 10.

1. Primary Heat Exchangers

 

The cost estimate for the primary heat exchangers in the reference
design, as reported in ORNL-4S5L1, has been changed from $7.3 million to
about $8.7 million to reflect the revisions to the design data, as indi-
cated in Table 4. The cost increase is also due to adding in the cost
of the baffles and to inclusion of the double-pipe cocolant-salt nozzles,

which had previously been assumed to be covered by the piping cost
10

ORNL-DWG T1-T323

   

 

Reactor cell wall

 

 

 

 

 

 

! 32/3
o e
U-SHELL U-TUBE >
E SECONDARY HEAT
i EXCHARNGER \
’ From Steam Gen,
' g~ & Reheaters in
KNDE-NaNOE-Na Steam Cell
SECONDARY T s
[ \\‘\ Li¥ BeF2 |
7 TN Y
; ‘L .
\ ~ - To Steam Gen.
i S —— 8& gzheatcerilin
| A — eam Ce
| 2N
g Penetration

 

  

. HEAT _
EXCHANGER

   

 

  
      

Return line

7LiF-BeF2-ThFh_-UFL
underneath

 

Scale:s 5/32 in. = 1 ft \

Fig. 2. MSER Reactor Cell Iayout Indicating Possible Location

for Secorndary Heat Exchanger and Pump. (One of four loops is shown.)
 

 

Table 2. BSelected Properties of the MSER Molten Salts
71iF-BeFg-ThF,~UF,  NaF-NaRF, 7LiF-BeF, KNOg-NaNO, -NalNO4
Composition, mole % 71.7-16-12-0.3 92-8 6634 Lh.2-48.9-6.9%
Molecular weight, approximate 6l 104 33 8L
Density, 1b/ft® at 1000°F 212 117 12k 105
Viscosity, 1b/ft-hr at 1000°F 41 3 29 3
Specific heat, Btu/1b-°F 0.32 0.36 0.57 0.37
Thermal conductivity, Btu/ft-hr-°F 0.67 to 0.68 0.23 0.58 0.33
Estimated cost, $/1b 57.00 0.50 12.00 0.15
Circulation required per loopb
for 556-MW(t) heat load:

1b/hr 23.h x 108 18.3 x 108 13.3 x 108 1Lk, 7 x 108

gpm 1k, 260 19,500 13,380 17,370
Liquidus temperature, °F 930 725 850 288

 

“Butectic composition.

bBased on properties at average temperatures in MSBR system.

“Based on 250°F At in modifie

d MSER.

1T
12

Table 3. Material Costs Used in Estimatesa

 

 

Hastelloy N Incoloy

Tubes, 3/8 in. diam $30/1p $28/11
1/2 in. diam and larger 20 17
Shells and liners 10 f
Heads 15 12
Baffles , 15 . VLE

Ringss"' e fiéé S ':'18 &
Tubesheets 20 18
Downcomers, large nozzles 15 12
Miscellaneous nozzles, etc. 20 18

 

®Includes cost of material, fabrication, transportation,
inspection, and installation ready for use.

allowance. It was also found that the inside diameter of the shell
stated in ORNL-4541 appiied to the inner liner rather than to the
outer shell.

The design data for the primary heat exchangers as modified to use
IiF-BeF; on the shell side are also shown in Table 4. These design
data have not been recalculated using the May 1971 revisions to the com-
puter program (see Introduction), but the effects of the changes could
be estimated by using their influence on the reference design primary
heat exchanger costs as a guide, as follows: tubes (+6.4%), shell and
liner (+8.7%), heads (-1.4%), rings (~1.0%), downcomers, U-bends and
baffles (+4.1%). |

The tubes and other portions of the primary heat exchanger in con-
tact with the fuel salt must be constructed of Hastelloy N. This was
also true in the reference design for the portions in contact with the

sodium fluoroborate salt. In the modified design, however, consideration
13

Table 4. Primary Heat Exchangers

 

Revised Reference Modified MSER

 

Design MSER With Third Loop

Capacity, MW(t), each of four units 556 556
Fuel salt temperatures, in—out, °F 1300~1050 1300—1050
Coolant salt temperature, in—out, °F 8501150 950—1200
Coolant salt NaF-NaBF, LiF-BeFg
Tube size (enhanced), OD x wall 3/8 x 0.035 3/8 % 0.035

thickness, in. "
Number of tubes 5803 6312
Length of tubes, ft 2. L 25.5
Heat transfer area, ft® 13,916 15,789
Iiner, ID x thickness, in. 67.6 x 2.5 70.3 X 2.5
Shell, ID ¥ thickness, in. 73.6 x 1/2 76.3 x 1/2
Pressure drops: tube side, psi 130 130

shell side, psi 116 118

Head thickness, in. 3/h 3/L
Number of baffles, disc and 21 34

doughnut, 3/8 in. thick
Overall heat transfer coefficient, 785 672—9hL

Btu/hr-ft3-°F

A. Material costs with Hastelloy N tubes and shell (in $lOOO):

 

 

Tubes, at $30/1b $ 2,L57 $ 2,970
Shells, at $10/1b hilk L87
Liners, at $10/1b 1,959 2,308
Heads, at $15/1b 141 150
Rings and tube sheets, at $20/1b 2,823 2,911
Downcomers, baffles, and double- 666 854
pipe coolant nozzles, at $15/1b

Installation sllowance 200 200

Total for four units $ 8,660 $ 9,880

(continued)
1

Table L4 (continued)

 

Revised Reference Modified MSER
Design MGSBR With Third Loop

 

B. Material costs with Hastelloy N tubes and Incoloy shell (in $1000) :

 

Tubes, at $30/1b $ 2,970
Shells, at $8/1b 350
Liners, at $8/1b 1,658
Heads, at $15/1b 150
Hastelloy N rings and tubesheets, at $20/1b 1,907
Incoloy rings, at $17/1b 812
Downcomer, at $12/1b 126
Double-pipe coolant nozzles, at $12/1b 65
Baffles, at $12/1b Lol
Installation allowance 200

Total $ 8,661

 

can be given to use of less expensive materials in the shell side of the
system, provided that nc moisture is present. The more conservative
approach is to use Hastelloy N for all portions of the secondary system,
and this is the basis for the cost estimates shown in Part A of Tables
1, 4, and 5. Since there has been noteworthy success in excluding water
from salt systems, however, 1t may be practical to use Incoloy, or a
similar material, in the secondary system. The estimated costs in this
case are shown in Part B of Tables 1, 4, and 5. It will be noted that
use of Incoloy would save about $3 million in total costs when indirect

charges are included.

2. Secondary Heat Exchangers

 

The secondary heat exchangers in the modified MSBR plant are en-
visioned as U-sghell and U-tube types, arranged vertically in the reactor
cell, as indicated in Pig. 2. The design data were generated on the

basis of four units with 3/8-in.-OD tubing. The arrangement was not
Table 5. Secondary Heat Exchangers

15

 

Capacity, each of four units, MW(t)

LiF-BeF, (tubes) temperatures, in—out, °F

KNO4-NalNO, -NaNO, (shell) temperatures, in—out, °F

Tube size (not enhanced), OD X wall thickness, in.

Number of tubes

Length of tubes, ft

Heat transfer surface, ft2

Pressure drops:

tube side, psi
shell side, psi

Shell, ID x wall thickness, in.

Number of baffles, crosscut, 3/8 in. thick

Tubesheet thickness, in.

Head thickness, in.

Overall heat transfer coefficient, Btu/hr-ft2-°F

Modified MSBR With

Third Loop

 

556
1200950
750-~1100
3/8 x 0.035
5989

Il

25,665

9.2
79.6

61.5 x 1/2
33

3

3/k

505

A. Material cost with Hastelloy N tubes and Incoloy shell (in $1000):

Tubes, at $30/lb
Shell, at $8/1b
Tubesheet, at $20/1b
Heads, at $15/1b
Baffles, at $12/1b
Nozzles, etc., at $20/1b
Installation allowance
Total for four units

$ 4,542

L83
458
102
1,018
80
200

$ €,883

B. Material cost with Incoloy shell and tubes (in $1000):

 

Tubes, at $27/1b
Shell, at $8/1b
Tubesheets, at $18/1b
Heads, at $12/1b
Baffles, at $12/1b
Nozzles, etc., at $18/1b
Installation allowance
Total for four units

$ 3,670

L83

 
16

optimized, however, and although sufficient for cost-estimating purposes,
there are indications that further study may be needed. For example,

the calculated shell diameter of over 60 in. is questionable for the U-
shell configuration. The tube size needs optimizing in that the 3/8-in.-
OD tubing is needed to minimize the LiF-BeF, inventory and surface re-
quirements, but it is relatively expensive compared to larger sizes (see
Table 3). Consideration could be given to use of eight units rather than
four, and to use of straight-tube designs, although space in the cell is
somewhat limited.

As previously discussed, there 1s a possible option in selecting
materials to be used on contact with the LiF-BeFy; salt. Part A of Table
5 shows the estimated direct cost of the secondary heat exchangers if
constructed with Hastelloy N tubes and heads, and Part B indicates the

cost if Incoloy is used for these parts.

3. Steam Generators

 

The cost estimate for the steam generators in the reference design
was changed from $6.3 million to $7.2 million to reflect the revisions
in the design data. The principal differences were due to an increase
in the number and length of the tubes and an increase in the thickness
of the tube sheets used in the cost estimate. The data and costs are
shown in Table 6.

The design data and the estimated cost of the steam generators for
the modified MSBR system using KNOz-NaNOg-NaNOz on the shell side are
also shown in Table 6. The lower total cost of the units for the modi-
fied design is primarily due to use of Incoloy rather than Hastelloy N.
It may be noted that the steam generators are designed for 555F enter-
ing feedwater rather than the 551°F temperature called for in the flow-
sheets. A technicality in the computer program made it necessary to
revise the number, but since the total amount of heat to be transferred
was not altered, the only sacrifice to accuracy was relatively small

velocity effects.
17

Table 6. Steam Generators

 

Revised Reference

Design MSEBR

Modified MSER
With Third Loop

 

For each of 16 units:
Capacity, MW(t)
Type

Major material of construction

121
U-shell, U-tube
Hastelloy N

 

Heat transport salt (shell side) NaF-NaBF,
Salt temperatures, in—out, °F 1150850
Feedwater temperature, °F 700
Steam temperature out, F 1000
Steam pressure, psia 3625
Tube size, OD y wall thickness, in. 1/2 x 0.077
Number of tubes 393
Tube length, ft 76
Heat transfer surface, ft® 3929
Shell, ID x wall thickness, in. 18.3 x 3/8
Number of baffles (3/8 in. thick) 18
Head (spherical) thickness, in. L
Pressure drops: tube side, psi 152
shell (salt) 61
side, psi
Overall U, Btu/hr-ft2-°F -
Material costs (all 16 units):
Tubes:; Cost, $/1b (20)
Total cost ($1000) $ 3,803
Shells: Cost, $/1b (10)
Total cost ($1000) 1,046
Heads: Cost, $/1b (15)
Total cost ($1000) 565
Tubesheets: Cost, $/1b (20)
Total cost ($1000) 1,016
Misc.: Cost, $/1b (20)
Total cost ($1000) 320
Installation allowance 480
Total cost ($1000) $ 7,230

121

U-shell, U-tube
Incoloy 800
KNOg -NaNOg ~NaNO4
1100-750

555

1000

3625

1/2 x 0.077

341

99

428

17 x 3/8

28

L

125
90

655

(17)

$ 3,269

(8)

910

(12)
ko6

(18)
821

(18)
306

480

 

$ 6,192

 
18

i, Steam Reheaters

 

The estimated cost of the steam heaters in the reference design
was revised from $1.7 million to $1.6 million to correspond to the re-
vised design data, as shown in Table 7. Although the revised unit has
more surface, the previously used price of Hastelloy N tubing did not
reflect the lower unit price of 3/h—in.—OD tubing as compared to 3/8-
in.-0D tubing.

The design data and estimated cost of the modified reheaters using
KNOz-NaNOg -NaNOs on the shell side are also shown in Table 7. TUsing
Incoloy rather than Hastelloy N accounted for the reduction in cost to
$1.2 million. It will be noted that the unit is designed for 550°F
entering cold reheat temperature, as taken directly from the high-pressure

turbine exhaust.

5. Reheat Steam Preheaters

 

Reheat steam preheaters were used in the reference design to heat
the high-pressure turbine exhaust from 550°F to 650°F before the steam
entered the reheaters to avoid possible problems of coolant-salt freezing.
The cost of the preheaters was underestimated in the reference design
report because the thickness of the spherical heads was used in the cal-
culations as l/2-in. rather than the correct value of 2—1/2 in. Purther,
the material costs assumed for the Croloy in the reference design appeared
too low. The revised cost estimate for the preheaters is now $92L4,000,
as shown in Table 8.

The preheater design was not optimized. Use of 3/8-in. tubes may
involve a cost penalty, and some improvement in costs might be obtained
if the number of units was increased.

The modified MSER with the third lcops added to trap tritium does
not require use of preheaters because of the low liquidus temperature of

the nitrate-nitrite salt.

6. General Effects of Revising and Modifying the Heat Transfer
Equipment

 

The total cost effects of revising the design data for the heat
transfer equipment in the reference design are summarized in Table 9.

The net increase of about $4 million (including indirect charges)
Table 7.

19

Steam Reheaters

 

Revised Reference

Modified MSBR

 

 

 

Design MSER With Third TLoop
For each of 8 units:
Capacity, MW(t) 36.6 36.6
Major material of construction Hastelloy N Incoloy 800
Heat transport salt NaF-NaBF, KOz -NalNOg-NalNOg
Salt temperatures, in—out, °F 1150-850 1100~750
Steam temperature in, °F 650 550
Steam temperature out, °F 1000 1000
Entrance steam pressure, psia 580 580
Tube size, OD ¥ wall thickness, in. 3/k % 0.035 3/4 % 0.035
Number of tubes Loo 696
Tube length 30 28
Heat transfer surface, ft2 2376 2520
Shell, ID % wall thickness, in. 21.2 x 0.5 21 % 0.5
Number of disc and doughnut baffles 21 & 21 30 & 29
Head thickness, in. 0.5 0.5
Pressure drops: tube side, psi 30 Lo
shell side, psi 60 90
Overall U, Btu/hr-ft2-°F 306 340
Material costs (all 8 units):
Tubes: $/11 $ (20) $ (17)
cost, in $1000 590 465
Shells: $/1b (10) (8)
cost, in $1000 327 210
Tubesheets:  $/1b (20) (18)
cost, in $1000 146 115
Heads: $/1v (15) (12)
cost, in $1000 72 52
Baffles: $/1b (15) (12)
cost, in $1000 151 109
Nozzles, etc: $/1b (20) (18)
cost, in $1000 80 65
Installation allowance 200 200
Total cost, in $1000 $ 1,566 $ 1,216

 
20

Table 8. Reheat Steam Preheaters

 

For each of 8 units:
Capacity, MW(t)
Major material of construction
Shell-side conditions:
Heated steam entrance temperature, °F
Entrance pressure, psia -
Tube-side conditions:
Heating steam entrance temperature, °F
Entrance pressure, psia
Tube size, 0D ¥ wall thickness, in.
Number of tubes
Tube length, ft
Heat transfer surface, ft2
Shell, ID x wall thickness, in.
Overall U, Btu/hr-ft3-°F
Head thickness, in.
Material costs (all 8 units), in $1000:
Tubes, at $18/1b
Shells, at $8/1b
Heads, at $10/1b
Tubesheets, at $18/1b
Nozzles, ete., at $18/1b

Installation allowance

Revised Reference
Design MSER

 

12.3
Croloy

551
595

1000
3600

3/8 x 0.065
603

13.2

781

20-1/h x 7/16
162

2-1/2

$ 252
88

296

323

T2

25

$ 1,056

 

 
21

Table 9. Revised Reference Design Costs for Heat
Transfer Equipment (in $1000)

 

Reference MSBR Revised Reference

 

 

Design® Design Costs
Primary heat exchangers $ 7,347 $ 8,660
Steam generators 6,270 7,230
Reheaters 1,668 1,565
Reheat steam preheaters 135 92k

$ 15,420 $ 18,379
Increase in reference design direct costs $ ¢ 2,959
Increase in total cost, including indirects $ 3,935
Reference design total cost® 202,654
Total revised reference design cost $ 206,589

 

8ps listed in ORNI-45k1.

bFor Hastelloy N fuel and coolant-salt systems.

results in raising the totsl estimated plant cost of the reference design
MSER plant from about $202 million to $206 million.

Use of Incoloy rather than Hastelloy N for the portions of the second-
ary system in contact with LiF-BeF, would save about $1.6 million in the
total cost (including indirect charges) of the primary heat exchangers,
about $1.3 million for the secondary heat exchangers, and about $200,000
for the secondary salt piping, for a total savings of about $3 million.

The costs of the heat transfer equipment on a square foot basis are
compared in Table 10. While the values are not particularly conclusive,
they indicate that the estimated costs are generally within reason for

this type of nuclear power station equipment.

L. SALT-CIRCULATING PUMPS

Since salt-circulating pumps of the size required for the 1000-MW(e)

MSER station have never been fabricated, the cost-estimating method used
22

Table 10. Estimated Direct Cost of Installed Heat Transfer
Equipment per Square Foot of Surface

 

Revised Reference Modified MSER

 

Design MSBER With Third Loop

Primary heat exchangers

Hastelloy N tubes and shell $ 155 $ 1h7

Hastelloy N tubes and Incoloy shell - 129
Secondary heat exchangers

Hastelloy N tubes and shell 67

Hastelloy N tubes and Incoloy shell L3
Steam generators 115 76
Steam reheaters &2 54
Reheat steam prehesters 149 none

 

in this study and in the reference design report is based on published
costs of similar pumps (as adjusted for capacity and head reqguirements),
on MSRE pump cost experience, and on the basis of considerable intuitive
Judgment. Table 11 indicates the pumping requirements which served as

a basis for assuming allowances for the pump costs in the modified MSER
plant.

Use of the third circulating salt system would add four pumps of
about 2700 hp each, would reduce the power requirements of another set
of four pumps from 3200 hp to 1800 hp each, and would eliminate the
need for the two 6000-hp each pressure-booster pumps in the feedwater
system. As shown in Table 12, the connected lcad of the pump motors is
reduced by a total of about 5,400 kW(e) in the modified system. If it
is assumed that all the pumping energy is usefully converted to heat,
about 5,400 kW(t) is thus not available in the modified system for con-
version into electric power at the average overall plant efficiency of
L h%. The net savings in auxiliary electric load is thus about 3,000
xW(e). With power worth 5.3 mills/kWhr, and 80% plant factor, this
amounts to about $lll,OOO/year. At 13.7% fixed charges, the savings is
equivalent to a plant investment of about $317,000. Credit for this has
been taken in Parts A and B of Table 1.
23

Table 11. Estimated Design Data and Allowances for Installed
Costs of Salt-Circulating Pumps

 

Modified MSER

 

Secondary-
Fuel-Salt Salt Pump Secondary- Tertiary-
Pumps Ref. MSER Salt Pump Salt Pump

 

For each of 4 pumps:

Actual capacity, gpm 14,255 18,768 13,380 17,372
Nomingl capacity, gpm 16,000 20,000 16,000 20,000
Average salt density, 1b/ft3 208 117 12k 105
Estimated total head, ft2 150 300 230 300
Estimated horsepower 2360 3210 1800 2680
Cost allowance, in $1000, $3300 $4L00 $2750 $3800

for total of 4 pumps

 

SEstimate based on calculated Ap's in heat transfer equipment.

Cost assumed to be in proportion to capacity and horsepower require-
ment.

Table 12. BEstimated Pumping Power Requirements and Worth of
Tmproved Efficiency of Modified MSER Cycle

 

Reference Design Modified MSER

 

MSER With Third Loops
Total pumping power, kW(e):
Pressure~-booster pumps 9,200 none
Fuel-salt pumps 7,039 7,039
Secondary-salt pumps 9,575 5,369
Tertiary-salt pumps none 7,994
58,81k 50, 502
Savings in pump power with modified system, 5, 400
kW(e)
Difference in heat inputs to systems from 5,400
pump work, kW(t)
Electric power potential of 5,400 kW(t) at 2,400
L4. 4% thermal efficiency, kW(e)
Net savings in power with modified cycle, 3,000
kW(e)
Capital cost worth of 3,000 kW(e) at 80% $817,000

plant factor, 13.7% fixed charges, and
power worth 5.3 mills/kWhr

 
2k
5. SALT INVENTORY COSTS

The modified primary heat exchangers will contain about 56 ft@
more fuel salt than those used in the reference design, as indicated in
Table 13. On the basis of the $57/1b fuel-salt cost used in ORNL-L4541,
this amounts to an additional investment of $671,000 for the MSER plant.
Following the procedures used in the reference report, however, this
capital cost is not included in the plant capital cost but in the fuel-
cycle cost. This would increase the fuel-cycle cost by about 0.013
mills/kWhr. (In both the reference and the modified plant designs it
was assumed that the cleanup costs for the fuel salt at the end of the
30-year plant life would be great enocugh to make it have essentially no
resale, or "sé}ap" value. )

The estimated price of the nitrate-nitrite salt used in the modified
design is 15 cents/lb as compared to 50 cents/lb for the sodium fluoro-
borate used in the reference design. Both of these salts are assumed to
have no resale value at end of the useful life of the plant.

As shown in Table 14, the estimated volume of the LiF-BeFz; used in
the secondary system is about 3200 ft®. Almost three-fourthé of this is
in the shell-side of the primary heat exchangers. Using the same prices
as in ORNL-4541, where 7Li is assumed to cost $120/kg, and "LiF and BeFy
to cost $16.50 and $7.50/1b, respectively, the estimated cost of 7LiF-BeF,
is about $12/1b. The total estimated cost of the secondary salt inventory
is about $4,800,000, as shown in Table 13. It is assumed that the salt
will last the lifetime of the plant without reprocessing or replacement
costs. At the end of 30 years it is assumed that the salt will have a
resale value of 50%, or $6/1b. (The salt could be used as the secondary
coolant in another MSER or as the carrier to make up new batches of fuel
salt.) The present worth of $2,400,000 thirty years hence at 8% interest
is $239,000, and credit for this has been taken in Table 1.
25

Table 13. Estimated Salt Inventory Costs

 

Reference Design Modified MSER

 

MSEBER wWith Third Loops
Fuel salt 7LiF-BeFy-ThF,-UF, 7LiF-BeF, -ThF,-UF,
Total volume,” ft2 2200 2256
Total weight, 1b 457,000 469,000
Total cost® $23,533,000 $ol, 204,000
Resale value after 30 yr 0 0
Secondary salt NaF-NaBF, 7LiF-BeFy
Total volume, ft2 8L00 3200°
Total weight, 1b 1,000,000 397,000
Average cost, $/1b $0.50 $l2d
Total cost $500,000 $k, 800,000
Resale value after 30 yr 0 $2, 400,000
Present worth, at 8% $239,000
Tertiary salt KNO5~NalNO, -NaNOg4
Total volume, ft3 - 8koo®
Total weight, 1b none 900, 000
Average cost, $/1b $0.15
Total cost $135,000
Resale value after 30 yr 0

 

®Includes 480 £+ in chemical processing plant.

bBased on fertile salt cost of about $57/lb and an average inventory

®See Table 11.
a

value of $31/1b in the chemical plant.

Based on 7Ii at $120/kxg, 7IiF at $16.50/1b, BeF, at $7.50/1b.

e .
Assumed to have same volume as reference design secondary system.
26

Table 1h. Estimated Volume of LiF-BeF, Salt in
Secondary System of Modified MSER

 

Primary heat exchanger volumes

 

Shell, ft2® per unit + 762 ft3

Head, ft2® per unit + 13

Tubes, ft2 per unit - 123

Liner, ft3 per unit - 95

Downcomer - 5

Baffles - 17

90° outlet bends + 19

Net volume one unit 554 £8

Total volume 4 units 2,216 £t2

Secondary heat exchanger volumes (tube side)

Tubes 133 £t

Head allowance _20

Volume in one unit 153 ft8

Total volume in L4 units 612

Secondary salt piping volumes
Volume of 35-ft 20-in. pipe
per unit, for total 4 units 306
Drain tank heel allowance 66
Total estimated volume of salt 3,200 ft@

 

 
27

INTERNAL DISTRIBUTION

1. J. L. Anderson Lo. H. C. McCurdy
2. C. F. Baes 41. H. A. McLain
3. H. F. Bauman 42, L. E. McNeese
L. 8. E. Beall 43, J. R. McWherter
5. C. E. Bettis L., A. 8. Meyer
6. E. S. Bettis 4s. A, J. Miller
7. F. F. Blankenship 46. R. L. Moore
8. E. G. Bohlmann k7. M. L. Myers
S. H. I. Bowers 48. E. L. Nicholson
10. R. B. Briggs 49. A. M. Perry
11. S. Cantor 50. T. W. Pickel
12. W. L. Carter 51-60. R. C. Robertson
13. C. W. Collins 61. M. W. Rosenthal
14. E. L. Compere 62. A. W. Savolainen
15. D. F. Cope, AEC-SSR 63. Dunlap Scott
16. W. B. Cottrell 64, J. H. Shaffer
17. S. J. Ditto 65. W. H. Sides
18. W. P. Eatherly 66. M. J. Skinner
19. J. R. Engel 67. A. N. Smith
20. A. P. Fraas 68. 0. L. Smith
2l. W. K. Furlong 69. 1. Spiewak
22. W. R. Grimes T0. R. A. Strehlow
23. A. G. Grindell TL. D. A. Sundberg
24. P. N. Haubenreich 72. J. R. Tallackson
25. R. E. Helms T3« R. E. Thoma
26. E. C. Hise 74. D. B. Trauger
27. H. W. Hoffman 75. H. L. Watts
28. P. R. Kasten 76. J. R. Weir
29. R. J. Kedl 77. M. E. Whatley
30. 5. S. Kirslis 78. G. D. Whitman
31. J. W. Koger 79. J. C. White
32. R. B. Korsmeyer 80. R. P. Wichner
33. Kermit Laughon, AEC-OSR 8l. L. V. Wilson
34. M. I. Lundin 82-83. Central Research Library
35. R. N. Lyon 84. Document Reference Section,
36. H. G. MacPherson Y-12 Library
37. R. E. MacPherson 85-86. ILaboratory Records
38. A. P. Malinauskas 87. Laborstory Records, RC
39. H. E. McCoy

EXTERNAL DISTRIBUTION

88-89. Division of Technical Information Extension

.90. Laboratory and University Division, ORO
91-93. Director, Division of Reactor Licensing
9L-95. Director, Division of Reactor Standards

96. A. R. DeGrazia, AEC-DRDT, Washington

97. D. Elias, AEC-DRDT, Washington

98. ©N. Haberman, AEC-DRDT, Washington
28

EXTERNAL DISTRIBUTION (contd.)

99-100. T. W. McIntosh, AEC-DRDT, Washington
101. J. Neff, AEC-DRDT, Washington
102, R. M. Scoggins, AEC-DRDT, Washington
103. M. Shaw, AEC-DRDT, Washington
104. M. J. Whitman, AEC-DRDT, Washington