Analysis of PWR Critical Configurations Vol 4 - TMI Unit 1

122 Pages·1995·1.115 MB·English

ORNL/TM-12294/V4
SCALE-4 Analysis of Pressurized Water
Reactor Critical Configurations:
(cid:0)
Volume 4 Three Mile Island
Unit 1 Cycle 5
M. D. DeHart
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Government or any agency thereof.
ORNL/TM-12294/V4
Computational Physics and Engineering Division
SCALE-4 ANALYSIS OF PRESSURIZED WATER REACTOR CRITICAL
(cid:0)
CONFIGURATIONS: VOLUME 4 THREE MILE ISLAND UNIT 1 CYCLE 5
M. D. DeHart
Date Completed: February 1995
Date Published: March 1995
Prepared under the direction of
Sandia National Laboratories
under Memorandum Purchase Orders 66-0162 and AD-4072
with Oak Ridge National Laboratory
Prepared by the
OAK RIDGE NATIONAL LABORATORY
managed by
MARTIN MARIETTA ENERGY SYSTEMS, INC.
for the
U.S. DEPARTMENT OF ENERGY
under contract DE-AC05-84OR21400

CONTENTS
Page
LIST OF FIGURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v
LIST OF TABLES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vi
ABSTRACT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vii
1. INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
2. OVERVIEW OF THE METHODOLOGY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.1 FUEL ASSEMBLY GROUPS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.2 DEPLETION CALCULATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.3 BURNUP-DEPENDENT NUCLIDE CONCENTRATIONS . . . . . . . . . . . . . . . . 8
2.4 SUBGROUP CROSS-SECTION PROCESSING . . . . . . . . . . . . . . . . . . . . . . . . 10
2.5 PREPARATION OF THE KENO V.a CORE MODEL . . . . . . . . . . . . . . . . . . . 11
3. PREPARATION OF THE TMI-1 CORE MODEL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
3.1 CORE DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
3.2 SAS2H ASSEMBLY GROUPS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
3.3 SIMILAR-BURNUP SUBGROUPING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
3.4 SAS2H DEPLETION CALCULATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
3.5 BURNUP-DEPENDENT INTERPOLATION OF ISOTOPICS . . . . . . . . . . . . . 22
3.5.1 Assembly Isotopics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
3.5.2 Subgroup Isotopics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
3.6 GENERATION OF SUBGROUP CROSS SECTIONS USING CSASN . . . . . . 25
3.7 COMBINING SUBGROUP CROSS SECTIONS USING WAX . . . . . . . . . . . . 25
3.8 PREPARATION OF A KENO V.a CORE MODEL . . . . . . . . . . . . . . . . . . . . . . 27
3.8.1 KENO V.a Mixture Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
3.8.2 KENO V.a Geometry Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
4. RESULTS AND CONCLUSIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
REFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
APPENDIX A. SAS2H CASE INPUT EXAMPLE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
APPENDIX B. SNIKR EXECUTION AND OUTPUT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
B.1 Automated SNIKR Execution Script . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
B.2 Sample SNIKR Output - Assembly Calculation . . . . . . . . . . . . . . . . . . . . 45
B.3 Sample SNIKR Output - Subzone Calculation . . . . . . . . . . . . . . . . . . . . . 48
B.4 SNIKR1 Source Listing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
B.5 SNIKR3 Source Listing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
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APPENDIX C. SCALE CSASN-SEQUENCE INPUT LISTINGS . . . . . . . . . . . . . . . . . . . . . 73
C.1 TMISUBZ1 Listing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74
C.2 TMISUBZ2 Listing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
C.3 TMISUBZ3 Listing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76
APPENDIX D. WAX INPUT LISTING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
APPENDIX E. KENO V.a INPUT LISTING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
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LIST OF FIGURES
Figure Page
1. Overview of the reactor critical calculation procedure. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2. SAS2H burnup model of assemblies within a fuel group. . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
3. TMI Unit 1 configuration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
4. TMI Unit 1 assembly geometry. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
5. One-eighth core representation of TMI Unit 1, BOC 5. . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
6. Dimensions of a partial control rod (APSR). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
7. Full-core assembly positions and core former configuration. . . . . . . . . . . . . . . . . . . . . . . . 29
8. Unit definitions based on assembly/core former component arrays. . . . . . . . . . . . . . . . . . . 30
9. KENO V.a relative fission density in TMI-1 one-eighth core. . . . . . . . . . . . . . . . . . . . . . . 33
10. Relative change in concentration for select fission products. . . . . . . . . . . . . . . . . . . . . . . 34
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LIST OF TABLES
Table Page
1. Nuclides updated by SAS2H . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
2. Set of fuel nuclides used in KENO V.a calculations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
3. Three Mile Island Unit 1 fuel/assembly design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
4. Assembly group data for BOC-5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
5. Isotopic content of fresh fuel for 2.64 and 2.85 wt % enrichments . . . . . . . . . . . . . . . . . . 18
6. Light-element masses used in SAS2H calculations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
7. Subgroup burnups for BOC-5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
8. Fuel group burn model used in SAS2H . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
9. Fuel assembly data for one-eighth core geometry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
10. Subgroups for one-eighth core assemblies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
11. Mixture numbers used in KENO V.a core model. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
12. Unit numbers used in KENO V.a core model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
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ABSTRACT
The requirements of ANSI/ANS-8.1 specify that calculational methods for away-from-reactor
criticality safety analyses be validated against experimental measurements. If credit is to be taken for
the reduced reactivity of burned or spent fuel relative to its original "fresh" composition, it is
necessary to benchmark computational methods used in determining such reactivity worth against
spent fuel reactivity measurements. This report summarizes a portion of the ongoing effort to
benchmark away-from-reactor criticality analysis methods using relevant and well-documented critical
configurations from commercial pressurized water reactors.
The analysis methodology utilized for all calculations in this report is based on the modules
and data associated with the SCALE-4 code system. Isotopic densities for spent fuel assemblies in
the core were calculated using the SCALE-4 SAS2H analytical sequence. The sources of data and
the procedures for deriving SAS2H input parameters are described in detail. The SNIKR code family
was used to extract the necessary isotopic densities from SAS2H results and to provide the data in
the format required for SCALE criticality analysis modules. The CSASN analytical sequence in
SCALE-4 was used to perform resonance processing of cross sections. The KENO V.a module of
SCALE-4 was used to calculate the effective multiplication factor (k ) for the critical configuration.
eff
The SCALE-4 27-group burnup library containing ENDF/B-IV (actinides) and ENDF/B-V (fission
products) data was used for all calculations.
This volume of the report documents a reactor critical calculation for GPU Nuclear
Corporation’s Three Mile Island Unit 1 (TMI-1) during hot, zero-power startup testing for the
beginning of cycle 5. This unit and cycle were selected because of their relevance in spent fuel
benchmark applications: (1) cycle 5 startup occurred after an especially long downtime of 6.6 years;
and (2) the core consisted primarily (75%) of burned fuel, with all fresh fuel loaded on the core outer
periphery. A k value of 0.9978 ± 0.0004 was obtained using two million neutron histories in the
eff
KENO V.a model. This result is close to the known critical k of 1.0 for the actual core and is
eff
consistent with other mixed-oxide criticality benchmarks. Thus this method is shown to be valid for
spent fuel applications in burnup credit analyses.
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