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Criticality Experiments with Subcritical Clusters of 2.35 Wt% and 4.31 Wt% 235U Enriched U02 Rods in Water with Uranium or Lead Reflecting Walls: Undermoderated Water-to-Fuel Volume Ratio of 1.6

Technical Report ·
DOI:https://doi.org/10.2172/1083949· OSTI ID:1083949
 [1];  [1];  [1]
  1. Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)
A series of criticality experiments with undermoderated (1.6 water-to-fuel volume ratio) 2.35 wt% and 4.31 wt% 235U enriched UO2 rods in water were performed to provide data on the reactivity effects of lead and depleted uranium reflecting walls. This data furnishes well defined benchmarks for use in validating calculational techniques employed in analyzing fuel shipping and storage systems having lead or uranium biological shields. For each fuel enrichment, the critical separation between three subcritical fuel clusters was observed to increase as either 77mm thick depleted uranium or 102mm thick lead reflecting walls were moved towards the fuel. A maximum critical separation was observed for both the lead and the depleted uranium reflecting walls with a water gap between the fuel clusters and the reflecting walls. For both fuel enrichments, this optimum water gap was about 25mm for the depleted uranium walls and about 10mm for the lead walls.
Research Organization:
Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)
Sponsoring Organization:
USDOE Office of Science (SC); US Nuclear Regulatory Commission (NRC), Washington, DC (United States). Office of Nuclear Regulatory Research; USDOE National Nuclear Security Administration (NNSA), Nuclear Criticality Safety Program (NCSP)
DOE Contract Number:
AC06-76RL01830
OSTI ID:
1083949
Report Number(s):
PNL--3926 Vol. 2
Country of Publication:
United States
Language:
English