Benchmark Evaluation of the NRAD Reactor LEU Core Startup Measurements

Conference · Mon Sep 19 04:00:00 EDT 2011

OSTI ID:1031653

Bess, John D. ^[1]; Maddock, Thomas L. ^[1]; Marshall, Margaret A. ^[1]

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1. Idaho National Lab. (INL), Idaho Falls, ID (United States)

The Neutron Radiography (NRAD) reactor is a 250-kW TRIGA-(Training, Research, Isotope Production, General Atomics)-conversion-type reactor at the Idaho National Laboratory; it is primarily used for neutron radiography analysis of irradiated and unirradiated fuels and materials. The NRAD reactor was converted from HEU to LEU fuel with 60 fuel elements and brought critical on March 31, 2010. This configuration of the NRAD reactor has been evaluated as an acceptable benchmark experiment and is available in the 2011 editions of the International Handbook of Evaluated Criticality Safety Benchmark Experiments (ICSBEP Handbook) and the International Handbook of Evaluated Reactor Physics Benchmark Experiments (IRPhEP Handbook). Significant effort went into precisely characterizing all aspects of the reactor core dimensions and material properties; detailed analyses of reactor parameters minimized experimental uncertainties. The largest contributors to the total benchmark uncertainty were the ²³⁴U, ²³⁶U, Er, and Hf content in the fuel; the manganese content in the stainless-steel cladding; and the unknown level of water saturation in the graphite reflector blocks. A simplified benchmark model of the NRAD reactor was prepared with a keff of 1.0012 ± 0.0029 (1σ). Monte Carlo calculations with MCNP5 and KENO-VI and various neutron cross section libraries were performed and compared with the benchmark eigenvalue for the 60-fuel-element core configuration; all calculated eigenvalues are between 0.3 and 0.8% greater than the benchmark value. Benchmark evaluations of the NRAD reactor are beneficial in understanding biases and uncertainties affecting criticality safety analyses of storage, handling, or transportation applications with LEU-Er-Zr-H fuel.

• Research Organization: Idaho National Laboratory (INL), Idaho Falls, ID (United States)
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA), Nuclear Criticality Safety Program (NCSP)
• DOE Contract Number: AC07-05ID14517
• OSTI ID: 1031653
• Report Number(s): INL/CON-11-20775
• Country of Publication: United States
• Language: English

Related Subjects

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
97 MATHEMATICS AND COMPUTING
BENCHMARKS
Benchmark
CONFIGURATION
CRITICALITY
CROSS SECTIONS
DIMENSIONS
EIGENVALUES
FUEL ELEMENTS
GRAPHITE
ICSBEP
INEEL
IRPhEP
ISOTOPE PRODUCTION
MANGANESE
NEUTRON RADIOGRAPHY
NEUTRONS
NRAD
Nuclear Criticality Safety Program (NCSP)
REACTOR CORES
REACTOR PHYSICS
SAFETY
STAINLESS STEELS
STORAGE
TRIGA
WATER SATURATION