SCALE-4 Analysis of Pressurized Water REactor Critical Configurations: Volume 5 - North Anna Unit 1 Cycle 5
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The requirements of ANSI/ANS 8.1 specify that calculational methods for away-from-reactor
(AFR) criticality safety analyses be validated against experimental measurements. If credit for the
negative reactivity of the depleted (or spent) fuel isotopics is desired, it is necessary to benchmark
computational methods against spent fuel critical configurations. This report summarizes a portion
of the ongoing effort to benchmark AFR criticality analysis methods using selected critical
configurations from commercial pressurized-water reactors (PWR).
The analysis methodology selected for all calculations reported herein was the codes and data
provided in the SCALE-4 code system. The isotopic densities for the spent fuel assemblies in the
critical configurations were calculated using the SAS2H analytical sequence of the SCALE-4 system.
The sources of data and the procedures for deriving SAS2H input parameters are described in detail.
The SNIKR code module was used to extract the necessary isotopic densities from the SAS2H results
and to provide the data in the format required by the SCALE criticality analysis modules. The
CSASN analytical sequence in SCALE-4 was used to perform resonance processing of the cross
sections. The KENO V.a module of SCALE-4 was used to calculate the effective multiplication
factor (keff) of each case. The SCALE-4 27-group burnup library containing ENDF/B-IV (actinides)and ENDF/B-V (fission products) data was used for all the calculations.
This volume of the report documents the SCALE system analysis of one reactor critical
configuration for North Anna Unit 1 Cycle 5. This unit and cycle were chosen for a previous analysis
using a different methodology because detailed isotopics from multidimensional reactor calculations
were available from the Virginia Power Company. These data permitted comparison of criticality
calculations directly using the utility-calculated isotopics to those using the isotopics generated by
the SCALE-4 SAS2H sequence. This reactor critical benchmark has been reanalyzed using the
methodology described above. The benchmark critical calculation was the beginning-of-cycle (BOC)
startup at hot, zero power (HZP). The k result was 1.0040, with a standard deviation of 0.0005.
