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ORNL-CF-77-391.txt
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ORNL-CF-77-391.txt
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-
DATE;
SUBJECT:
TO:
FROM:
Coe B =
OAK RIDGE NATIONAL LABORATORY
UNION CARBIDE CORPORATION
uumj;élsmn 0 R N L
rosr e s0x x CENTRAL FILES NUMBER
OAK RIDGE, TENNESSEE 37830
ORNL/CF-77/391
August 25, 1977
Decommissioning Study for the ORNL Molten-Salt Reactor
Experiment (MSRE)
Distribution
C. D. Cagle and L. P, Pugh
ABSTRACT
Job descriptions and cost estimates have been pre-
pared for two methods of decommissioning the shutdown
Molten-Salt Reactor Experiment (MSRE). Dismantling of all
process equipment for disposal in a solid-waste storage
area is estimated to cost $11,600,000. Transferring all
contaminated external equipment to the reactor containment
cell followed by filling the cell with concrete for in-
place entombment is estimated to cost $4,770,000. Also
included are a history of the reactor, a description of
the components, and a list of references.
This document has been approved for relesse
to the public by:
Damd (Jw«vm
chh.n_r ! mfannauon Officer
NOTICE This document contains information of a preliminary’
noture ond was prepared primarily for internal use ot the Oak
Ridge Notional Laboratory. It is subject to revision or cor-
rection ond therefore does not represent.a final report. The in-
formation is only for official use ond no release to the public
shall be made without the approval of the Law Department of
Union Carbide Corporatian, Nuclear Division.
e L £T
-5
ok
CONTENTS
ABSTRACT .
1. INTRODUCTION .
2, GENERAL INFORMATION
2,1 General Description
2.2 History |
2.3 Reactor Site and Building .
2.4 Shielded Containment Cells .
2.5 Reactor Primary System .
'2.5.1 Reactor Vessel and. Core
2.5.2 Thermal Shield .
2.5.3 Primary System Pump
2,.5.4 Primary System Heat Exchanger
5
2.5. Fuel Pump Overflow Tank
2.5.6 TFuel-Salt and Flush-Salt Drain and Storage Tanks .
2.6 Reactor Secondary System .
2.6.1 Heét Exchanger .
2,6.2 Coolant Circulating Pump .
2.6.3 Radiator .
2.6.4 Secondary System Piping
'2.6.5 Coolant Drain Tank .
2.7 Fuel-Pfocessing System .
2.8 TFreeze Flanges .
2.9 ?reeze Valves
2.10 Salt Systems Heaters and Therfial Insulation
- 2.10.1 Reactor Furnace |
2.10.2 Fuel-Salt-Pump Furnace .
2.10.3 Coolant-Salt-Pump Heaters and Insulation .
2
.10.4 Fuel- and Flush-Salt-Drain-Tank Heaters and
Insulation . '
N
.10.5 Fuel-Storage-Tank Heaters and Insulation .
2.10.6 Coolant-Salt-Drain-Tank Heaters and Insulation .
2.10.7 . Heat-Dump Radiator Heaters and Insulation
69
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69
70
3.
4.
2.10.8 Piping Heaters and Insulation . . . . .
2.10.9 Heat-Exchanger Heaters and Insulation .
2.10.10 Heater and Thermocouple Leads . . . . .
2.11 Sampler-Enricher . . . . . . ¢« ¢ ¢« ¢ v ¢ o o . &
2.12 Nuclear Instrumentation . . . . « . « « « « .« &
2.13 Accessory Systems . . . . ¢ . ¢ ¢ o o 2 o 0 o .
2.13.1 Cover-Gas System . . . . .« « « « « o =
2.13.2 Leak-Detector System . . . . . . . 7';
2.13.3 Lubricating-0il Systems . . . . . . .
2.13.4 Component-Cooling Systems . . . . . . .
2.13.5 Cooling-Water System . . . . . . . .
2.13.6 0ff-Gas Disposal System . . . . . . . .
2.13.7 Containment Ventilation System .
2.13.8 Liquid-Waste -System . . . . . « . « .+ &
2.14 Vapor Condensing System . . . . . . . . . . ..
MSRE PRESENT CONDITIONS . . . « & ¢ « o« « o« o o o o o
3.1 Securing the Process Systems . . . . . . . . . .
- 3.2 Post-Operation Examination . . . . « . . . . . .
3.3 Surveillance . . . ¢ ¢ ¢ ¢ + « ¢ o e 0 s 4 s e
3.4 Surplus Equipment Removal . . . . . . . . . . .
3.5 Site Utilization . . . . . ¢« ¢« ¢« & « « & &+ & &
3.6 Current Radiation and Contamination Levels . . .
DECOMMISSIONING ALTERNATIVES . . . . . . « « « + « . .
4.1 Removal and Disposal of All Radibactifie Material
: the Containment Cell Structure . . . . . . . . .
4.2 Entombment in Place . . . . . ¢ % ¢ ¢ o « o o
4.3 Arguments Favoring Dismantling and Disposal of Radio-
active and Contaminated Items . . « « ¢ « « + =«
4.4 Arguments Favoring Entombing the Reactor and Associated
Radioactive and Contaminated Items and Materials
ReaCtor Cell . I. - L] . . - » [ ] - - * . . - . - * .
in the
5. WORK INVOLVED IN DISMANTLING AND DISPOSING OF RADIOACTIVE AND
CONTAMINATED ITEMS IN A SOLID-WASTE STORAGE AREA . . .
5.1 Preparatory Work . . . « . o « « &« ¢ o 0 4 o 0
* - .
97
97
98
99
99
99
5.1.
s
5.1.2
5.1.3
5.1.4
5.1.5
5.1.6
5.1.7
5.2.1
5.2.2
5.2.
5.2,
5.2.
5.2.
5.2.
- 5.2.
5.2,
O 0 ~N O W o~ W
Flushing System for the Reactor Tank and Other
Primary System Components
Reactor Cell Flooding System .
Work Shielding .
Transport Shields and Waste Storage Provisions .
Disposable Waste Containers
Miscellaneous Cutting and Handling Tools .
Retrievable Storage Requirements . . .
5.2 Remote bismantling Work
Clearing the Cell Around the Reactor .
Segmenting and Disposal of the Thermal Shield and
the Reactor Vessel . e i e e s e
5.2.2.a Alternative to Segmenting the Reactor
Vessel -
Drain-Tank Cell
Fuel-Processing Cell .
Cell Ventilation System
O0ff-Gas System .
Liquid-Waste Disposal System .
Coolant-Salt System
Miscellaneous Contaminated Items .
5.2.9.a Component-Cooling Air System .
15.2.9.b Sampler-Enricher
5.2.9.c Treated-Water System
WORK INVOLVED IN ENTOMBING ALL RADIOCACTIVE AND CONTAMINATED
ITEMS IN THE REACTOR CELL
6.1 Preparatory Work .
6.1.1 Flushing System for the Primary Salt Drain Tanks
and the Fuel-Processing Equipment
6.1.2 Air Exhaust System for the Reactor Cell
6.1.3 Tooling . . . .
6.2 Preparing Reactor Cell to Accommodate Contaminated Items
from Other Cells and Areas . . . . . .
6.2.1
Clearing Top of Cell and Installing Temporary
Ventilatlon Duct . . c e e e
’
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107
. 107
108
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. 111
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116
6.2.2 Sealing the Existing 30-In. Cell Ventilation
Duct at the Cell Wall
6.2.3 Closure of the Opening Between the Reactor and
Drain-Tank Cells .
6.2.4 Enlarging Space in the Reactor Cell
6.3 Transfer of Disposable Items to the Reactor Cell .
6.3.1 Drain-Tank and Fuel-Processing Ceil Components .
6.3.2 Disposal of Existing Reactor Cell Ventilation
: Duct and Off-Gas Lines . . . . «. « « .« « .« .
6.3.3 Secondary Decay Volume and Charcoal Traps
6.4 | Filling the Reactor Cell with Concrete .
6.5 Decontamination of Afea.
6.5.1 Drain-Tank Cell
6.5.2 — Fuel-Processing Cell . . . . . . « . ¢« « « « &
6.5.3 Liquid-Waste Storage Cell
6.5.4 Containment Ventilation System .
6.5.5 Special Equipment Room - Coolant Cell Area .
7. REFERENCES .
APPENDIX A - JOB LISTING FOR DECOMMISSIONING THE MSRE BY
DISMANTLING AND DISPOSAL .
APPENDIX B - JOB LISTING FOR DECOMMISSIONING THE MSRE BY
ENTOMBMENT . C e e e | .
DISTRIBUTION .
Page
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123
215
275
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
O 0~ o U~ W -
. - . . . - - . .
Ny N &1 = = | = = = = = = et
N = O W Ny W N+ O
* . . . - * - - . * - - -
LIST OF FIGURES
" ORNL Area Map
Plot Plan, Molten-Salt Reactor Experiment.(Bldg. 7503)
Front View of Bldg. 7503 .
Rear View of Bldg. 7503 During MSRE Construction .
Plan at 852-ft Elevation .
Plan at 840-ft Elevation .
Elevation, Bldg. 7503
Shield Block Arrangement at Top of Reactor Cell
Shield Block Arrangement at Top of Drain-Tank Cell .
Typical Penetration Assembly - Reactor Cell
Fuel System_Process_Flow Sheet .
Simplified Design Flow Sheet of the MSRE .
Primary and Secondary Salt Systems .
Reactor Cell During Assembly of Components .
Reactor Vessel .
Cross Section - Reactor Vessel and Access Nozzle .
Reactor Vessel Hanger Rods .
Typical Graphite Block Arrangement .
Control Rod and Drive Assembly .
Thermal Shield Components
Fuel Pump
Fuel Pump Motor and Rotor Assembly Showing Flange Bolt
Extensions . . . .+ « ¢ ¢ ¢« o 0 v e e v e e e e e e e .
Primary Heat Exchanger . . . . . .
Primary Heat Exchanger Subassemblies .
Fuel Pump Overflow Tank
Fuel Drain Tank System Process Flow Sheet
Fuel-Salt Drain Tank .
Fuel Drain Tank Steam Dome Bayonet Assembly
Coolant System Process Flow Sheet
Radiator Assembly
Radiator Coil and Enclosure
Page
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bt
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Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
vFigure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Fuel-Processing Cell . . . . . . . . . . . . . .
Simplified Fuel-Processing System Diagram . . .
Fuel-Processing System Process Flow Sheet . . .
Fuel Storage Tank . . . & ¢« ¢ v v ¢ « v o o o &
Sodium Fluoride Filled Trap . . « . + + « « « &
Freeze Flange and Clamp . . . . . . . . . . . .
-
*
Freeze Flange Clamping Frame Showing Assembly and Dis-
assembly . . . . . . . . 0 0 0 0 0 e 0 e e 0 e
Freeze Valve in Line 103 . . . . . . . . . . . .
Freeze Valve in Lines 107, 108, 109, and 110 . .
Freeze Valve in Lines 111 and 112 . . .
Freeze Valve in Lines 204 and 206 .. . . . . .
Removable Heater for 5-In. Pipe . . . . . . . .
Schematic Representation of Fuel-Salt Sampler-Enricher
Dry Box - . - . - - . . - . . . - - - . . - *
Elevation View of Nuclear Instrument Penetration .
Plan View of Nuclear Instrument Penetration . .
Schematic Diagram of Leak-Detected Flange Closure
Schematic of Air Flow Diagram Containment Ventilation
System . o & ¢« 4 4 e 4 4 v e e e e e e e e e e s
Liquid-Waste System Process Flow Sheet . . . . .
Diagram of Vapor-Condensing System . . . . . . .
Reactor Assembly Storage Container Concept . . .
63
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80
86
87
89
109
Table 1
Table 2
Table 3
Table 4
Table 5
LIST OF TABLES
Composition and Properties of INOR-8 . . . . . . .
Reactor Vessel and Core Design Data and Dimensions .
Radiation Levels Measured in 1977 Using an Ionization
Chamber . . . ¢« & ¢ v ¢ o o s « s o o o o s o o =
Dismantling -~ Cost Estimate Summary Sheet . . . . .
Entombment - Cost Estimate Summary Sheet . . . . . .
Page
26
27
95
100
114
e &
I‘l"-
11
1. INTRODUCTION
Research and development programs dealing with nuclear reactors and
their radioactive products have been carried out at ORNL since its
beginning in 1943. An increasing number of radioactive and radioactively.
contaminated facilities have been shut down due to completion of programs
or to being supplanted by more up~to-date facilities. Since these shut-
: down facilities contain hazardous amounts of both fixed and removable
radioactive materials, they must be kept under constant surveillance and
structurally maintained to preclude unauthorized entry by personnel and
to ensure against the release of radioactive contaminants to the environ-
ment. A portion of the financing and all personnel attention required
. for surveillance and maintenance of these facilities must be supplied by
on-going programs not related to the original programs which produced
the facilities. Although some advantage is gained in delaying final dis-
position of such shutdown facilities to await decay of relatively short-—
lived nuclides, further delay not only penalizes other programs but also
increases the risk of violation of containments due to deterioration or
accident.
The shutdown facilities include four reactors: the Molten-Salt
Reactor Experiment (MSRE), shut down in 1969; the Homogeneous Reactor
Experiment No. 2 (HRE-2), shut down in 1961; fhe Low-Intensity Testing
Reactor (LITR); shut down in 1966; and the Oak Ridge Graphite Reactor
(OGR), shut down in 1963. This report considefs the final disposal of
the MSRE.
The two methods of disposal considered are: (1) removal and burial
of all radioactive and contaminated systems components in a solid-waste |
disposal area; and (2) entombment of the more radioactive items in con-
crete within the existing below-grade concrete-shielded cells. Both
approaches assume that the 233U now stored in drain tanks in a shielded
cell adjacent to the reactor cell will have been removed prior to begin-
ning the decommissioning.
- This Feport contains a brief history of the project and sufficiently
detailed descriptions of the radioactive and auxiliary systems to expiain
12
the work that will be required to accomplish the decommissioning. More
detailed descriptions of the systems and components can be found in the
references. -
The MSRE was a 10-MW reactor built to investigate the practicality
of_the molten-salt concept for central power station applications. The
reactor and its accessory components are located in a group of mostly
below-grade shielded concrete cells within a mill-type building remote
from the main ORNL area. The last charging of fuel salt containing 233y
as the fissionable species remains stored in two drain tanks in a cell
adjacent to the reactor cell. This salt must be heated to above
300°F annually to recombine radiolytically produced fluorine gas. Due
to.the presence of the fuel and the residual radiocactive fission and
corrosion products within it and distributed throughout the reactor pri-
mary system and fuel-processing system, a filtered ventilation system
must be maintained in operation. Additionally, varying degrees of sur-
veillance and maintenance efforts must be exercised on a daily, a monthly,
and an annual basis to guarantee that the reactor remains environmentally
safe.
2. GENERAL INFORMATION
2.1 General Description
The MSRE was a single-region, unclad—graphite—modérated, homogeneous -
fuel type reactor with a design heat generation of 10 MW. The cir-
culating fuel solution was a mixture of lithium, beryllium, and zirconium
fluoride salts containing uranium fluoride as the fuel. The mixture had
an euctectoid liquidus point of 840°F and operated normally at 1200°F core
outlet temperature. Reactor heat was transferred from the fuel salt to
a similar coolant salt and then dissipated to the atmosphere.
2.2 History
The MSRE was constructed during the years 1961-1964 in a building
originally built for molten-salt reactor experiments for the Aircraft
t 0 9
vre
¢« v ¥
it
13
Nuclear Propulsion Program (ANP). The purpose of the‘MSRE was to dem-
onstrate that such a reactor could be constructed and maintained without
undue difficulty and could be operated safely and reliably. Additional
objectives were to provide the first large-scale; long-term, high-
temperature tests in a reactor environment of the fuel sélt, graphite
moderator,-and high-nickel-base alloy (INOR~-8) construction material.
The reactor first reached criticality on June 1, 1965, and concluded
operation on December 12, 1969. During this time the reactor accumulated
72,441 MW-hrs using ‘23%U fuel and 33,296 MW;hrs.using 233y fuel for a
total of 105,737 MW~hrs which is equivalent to 13,217 equivalent full-power
hours at 8.0 MW full power.
2.3 Reactor Site and Building
The MSRE 1is located in Melton Valley about one~half mile southeast of
.the main ORNL area (Figure 1) near the High Flux Isotope Reactor (HFIR)
and the Homogeneous Reactor Test (HRT) sites. A plot plan of the reactor
building complex is shown in Figure 2. Figures 3 and 4 ére views of the
front and rear of the building.
The building is constructed of steel framing and.asbestos cement
type corrugated siding with a sheet steel interior finish. Essentially
all portions of the building below grade are constructed of reinforced
concrete. Figure 5 is a plan of the reactor building at grade level, and
Figure 6 1s a plan 12 ft below grade showing the shielded cells and adja-
cent working areas. Figure 7 is an elevation through the cells. The |
west half of the building at grade level is about 42 ft wide,'157 ft long,
and 33 ft high. This high-bay or "crane-bay" area houses the reactor cell
drain-tank cell, coolant-salt '"penthouse'", and most of the auxiliary cells.
It is serviced by two bridge cranes, one equipped with a 30-ton hoist and
the other with both a 3-ton and a 10-ton hoist. The east half is 38 ft
‘wide, 157 ft long, about 12 ft high. This section contains the control
rooms, maintenance shops, change rooms, and some offices. (As explained in
Section 3.5, some of these areas are now in use by groups not related to
the MSRE program.)
Most of the west half of the below-grade level is occupied by the
reactor cell, drain~tank cell, and auxiliary cells. The east half con-
tained an office, a maintenance shop, and a chemical_laboratory.
14
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