ORNI./TM-12027
U0-522, -810, -811
. OAK RIDGE
NATIONAL, .
LABORATORY Options for Treating
High-Temperature Gas-Cooled
Reactor Fuel for Repository Disposal
A. L. Lotts
W. D. Bond
C. W. Forsberg
R. W. Glass
F. E. Harrington
G. E. Michaels
K. J. Notz
R. G. Wymer
r
MANAGEDBY
MARTINMARIETTAENERGYSYSTEMS,INC.
FORTHEUN;TEDSTATES DISFR;L_L,;. _ " 'Z.............. ' ,,.,
, ,_,,..,_.,ML,qT f<-'UNLiMI ]ED
DEPARTMENTOFENERGY
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ORNL/TM--12077
DE92 014909
OPTIONS FOR TREATING HIGH-TEMPERATURE GAS-COOLED
REACTOR FUEL FOR REPOSITORY DISPOSAL
A. L. Lotts**
W. D. Bond
C. W. Forsberg
R. W. Glass*
F. E. Harrington**
G. E. Michaels
K. J. Notz
R. G. Wymer**
Chemical Technology Division
*Engineering Division
**Consultant
Date Published: February 1992
M ,SIE
Prepared by the
OAK RIDGE NATIONAL LABORATORY
Oak Ridgc, Tennessee 37831-2008
managed by
MARTIN MARIETTA ENERGY SYSTEMS, INC.
for tile
U.S. DEPARTMENT OF ENERGY
under contract r3.E-AC05-84OR21400
CONTENTS
FIGURES ..................................................... vii
TABLES ix
ABSTRACT ................................................... xi
1. INTRODUCTION 1
1.1 OBJECTIVES .......................................... 1
1.2 SCOPE ............................................ 1
1.3 BASIS OF THE ASSESSMENT ............................ 2
1.4 ASSUMPTIONS ......................................... 2
1.5 UNIQUE ASPECTS OF HTGR FUEL ....................... 3
2. INSTITUTIONAL ISSUES ..................................... 5
2.1 REPOSITORY WASTE ACCEPTANCE CRITERIA ............ 5
2.2 CARBON-14 ........................................... 7
2.3 APPLICABLE RADIATION PROTECTION STANDARDS ...... 7
2.4 DISPOSAL OF RADIOACTIVE PROCESSING WASTE ........ 7
2.5 SAFEGUARDS: ISSUES RELATED TO NON-WEAPONS
STATES ............................................ 8
2.6 REFERENCES ......................... . ............... 9
3. DESCRIPTION OF HTGR FUELS ............................. 11
3.1 INTRODUCTION ...................................... 11
3.2 FORT ST. VRAIN FUEL ................................ 12
3.2.1 Physical and Chemical Description of Fort St. Vrain Fuel .... 12
3.2.2 Quantities of Fort St. Vrain Fuel ...................... 17
3.2.3 Radiological Properties of Fort St. Vrain Fuel ............ 19
3.3 PEACH BOTFOM-1 REACTOR FUEL ..................... 22
3.4 COMPARISON TO OTHER NON-STANDARD FUELS ........ 24
3.5 FUTIJRE HTGRS ...................................... 25
3.6 REFERENCES ........................................ 27
4. OVERVIEW OF OPTIONS ................................... 29
4.1 WHOLE-BLOCK DISPOSAL ............................. 29
4.2 DISPOSAL WITH PRIOR REMOVAL OF GRAPHITE ........ 33
4.3 DISPOSAL WITH DISSOLUTION ,.)F SPENT FUEL .......... 34
5. WHOLE BLOCK DISPOSAL .................................. 35
5.1 INTRODUCTION ...................................... 35
5.2 ACCEPTABILITY OF WHOLE BLOCK DISPOSAL 35
5.2.1 Previous Studies and Experiments ...................... 35
5.2.2 Comparison of the Characteristics of HTGR Spent
Fuel with Repository Acceptar, ce Requirements ........... 37
'8*
ill
5.2.2.1 Allowable Release Rates for Radionuclides
from the Repository ........................ 37
5.2.2.2 Allowable Organics in a Repository ............ 39
5.2.2.3 Combustibility ............................ 40
5.2.3 Comparison of HTGR and LWR Spent Fuel
Under Repository Conditions ....................... 41
5.2.3.1 Physical Effects ........................... 41
5.2.3.2 Chemical Effects .... ....................... 42
5.2.3.3 Combined Physical Form and Chemical Effects ... 44
5.2.4 Options for Improved Whole Block Disposal ............ 44
5.3 REPOSITORY ENGINEERING AND COST
CONSIDERATIONS . ........... 45
5.3.1 Repository Engineering Limits ........... ........ .... 45
5.3.2 Heat Limits ..................................... 46
5.3.3 Volume Limits ................................... 47
5.3.4 Waste Form .................................... 48
5.3.5 Relative HTGR and LWR Spent Fuel Disposal Costs ..... 49
5.4 REFERENCES ..................... • ................. 50
6. DISPOSAL WITH REMOVAL OF GRAPHITE .................. 53
6.1 OPTIONS AVAILABLE ................................ 53
6.2 PHYSICAL SEPARATION OF GRAPHITE ................ 53
6.3 CHEMICAL SEPARATION OF GRAPHITE (BURNING) ..... 54
6.4 POSSIBLE IMPROVEMENTS TO FUTURE HTGR FUEL .... 55
6.5 STATUS OF TECHNOLOGY ............................ 56
6.6 REFERENCES ....................................... 57
7. DISPOSAL WITH DISSOLUTION OF FUEL .................... 59
7.1 OVERALL FLOW SHEET .............................. 59
7.2 HEAD-END OPERATIONS ............................. 61
7.3 SOLVENT EXTRACTIONS ............................. 63
7.4 OFF-GAS TREATMENT ............................... 64
'7.5 LIQUID AND SOLID WASTE PROCESSING ............... 64
7.6 STATUS OF TECHNOLOGY ............................ 65
7.7 REFERENCES ....................................... 66
8. SCHEDULES AND COSTS .............. .................... 69
8.1 DEVELOPMENT COSTS ............................... 69
8.2 CAPITAL COSTS ..................................... 71
8.3 SCHEDULES ....................................... 71
8.4 OPERATING COSTS .................................. 72
8.5 SUITABILITY OF WASTE FOR THE REPOSITORY ........ 72
9. CONCLUSIONS ....................................... 73
9.1 CONCLUSIONS ON WHOLE BLOCK HTGR SPENT
FUEL DISPOSAL ..................................... 73
iv