Evaluation of Hanford B Reactor Experiments (PTA-069 and PTA-084) for Code and Data Benchmarking

Abstract

Experimental data on isotopic concentrations in irradiated nuclear fuel are essential for the validation of computational methods and nuclear data applied in the reactor modeling and simulations used in spent fuel safety and nuclear safeguards. This study investigates the potential use of recently declassified experimental data from the Hanford B reactor as a reactor and spent fuel benchmark. The experiments, performed in 1967, were the first in a series of carefully-designed tests to measure fuel performance and production capabilities at different locations in the reactor and for different exposures. Unlike most spent fuel benchmarks involving commercial fuel, the Hanford B data include unique measurements for very low exposure production fuel, with burnups less than 2,900 MWd/MTU. This report provides an assessment of the measurement data, uncertainties, design data, and operating history documentation, and describes preliminary benchmark models and simulation results. Areas where additional information would improve the quality of the benchmark are identified, as are potentially significant deficiencies in currently available nuclear cross-section data for simulating low-exposure irradiations.

Reactor Fuel Isotopics and Code Validation for Nuclear Applications

“…The general agreement seen between the predicted and measured actinides for PWR, BWR, VVER, and RBMK samples, on the other hand, are not seen in the most recent study looking at the Hanford B sample using SCALE 6.1-ENDF/B-VII. 28 As seen in Fig. 35, the 239 Pu concentration is predicted within 3.5%, but the 240 Pu is under-predicted by 38%.…”

“…The impact was potentially due to large uncertainties in 239 Np neutron capture cross sections. 28 It was concluded that the use of different sources of currently available nuclear data evaluations did not resolve the large differences in predicted 240 Pu, and these discrepancies are observed for many different codes. Further investigation of these discrepancies in the low exposure scenarios such as those seen for Hanford B is required to resolve the cause of the error and recommend improvements to current evaluated nuclear data.…”

“…Recently declassified experimental data from the Hanford B reactor are included within this report. 28 The High Power Channel-type Reactor, or Reaktor Bolshoy Moshchnosti Kanalnyy (RBMK), is a Russian graphite-moderated reactor that uses uranium oxide fuel and is cooled by light water. A total of 11 RBMK reactors currently operate in Russia, and the units in the Ukraine and Lithuania have been shut down.…”

“…A recent study at ORNL has shown the importance of correctly modeling the neutron capture of 239 Np to accurately obtain 240 Pu concentrations for low burnups typically found in plutonium producing reactors. 28 The main route for production of 240 Pu from low enriched uranium for commercial fuel exposures is 238 U→ 239 U→ 239 Np→ 239 Pu→ 240 Pu. However, at very low exposures, the production of 240 Pu from neutron capture in 239 Np is an important path.…”

“…Due to the quality and quantity of PWR data, most of the focus has been on validation of samples from PWRs. 10,13,16,18,20,21,23,24,25 However, varying degrees of validation work have been published on BWR 19 , VVER 12 , RBMK 12 , and Hanford B data 28 , as well.…”