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Title: Validation of HELIOS for ATR Core Follow Analyses

This work summarizes the validation analyses for the HELIOS code to support core design and safety assurance calculations of the Advanced Test Reactor (ATR). Past and current core safety assurance is performed by the PDQ-7 diffusion code; a state of the art reactor physics simulation tool from the nuclear industry’s earlier days. Over the past twenty years, improvements in computational speed have enabled the use of modern neutron transport methodologies to replace the role of diffusion theory for simulation of complex systems, such as the ATR. More exact methodologies have enabled a paradigm-shift away from highly tuned codes that force compliance with a bounding safety envelope, and towards codes regularly validated against routine measurements. To validate HELIOS, the 16 ATR operational cycles from late-2009 to present were modeled. The computed power distribution was compared against data collected by the ATR’s on-line power surveillance system. It was found that the ATR’s lobe-powers could be determined with ±10% accuracy. Also, the ATR’s cold startup shim configuration for each of these 16 cycles was estimated and compared against the reported critical position from the reactor log-book. HELIOS successfully predicted criticality within the tolerance set by the ATR startup procedure for 13 out ofmore » the 16 cycles. This is compared to 12 times for PDQ (without empirical adjustment). These findings, as well as other insights discussed in this report, suggest that HELIOS is highly suited for replacing PDQ for core safety assurance of the ATR. Furthermore, a modern verification and validation framework has been established that allows reactor and fuel performance data to be computed with a known degree of accuracy and stated uncertainty.« less
Authors:
 [1] ;  [1] ;  [1] ;  [1]
  1. Idaho National Lab. (INL), Idaho Falls, ID (United States)
Publication Date:
OSTI Identifier:
1177209
Report Number(s):
INL/CON--13-30718
TRN: US1500145
DOE Contract Number:
AC07-05ID14517
Resource Type:
Conference
Resource Relation:
Conference: PHYSOR 2014. The role of reactor physics toward a sustainable future, Kyoto (Japan), 28 Sep - 3 Oct 2014
Research Org:
Idaho National Laboratory (INL), Idaho Falls, ID (United States)
Sponsoring Org:
USDOE Office of Nuclear Energy (NE)
Country of Publication:
United States
Language:
English
Subject:
22 GENERAL STUDIES OF NUCLEAR REACTORS; ATR REACTOR; REACTOR CORES; H CODES; VALIDATION; COMPARATIVE EVALUATIONS; REACTOR SAFETY; NEUTRON TRANSPORT THEORY; ACCURACY; COMPUTERIZED SIMULATION; POWER DISTRIBUTION; CONFIGURATION; CRITICALITY; DESIGN; NUCLEAR FUELS; PERFORMANCE; TOLERANCE; VERIFICATION Advanced Test Reactor; As-Run; Core Follow; Critical Eigenvalue; Fuel Inventory; HELIOS; Startup Prediction