Criticality Experiments with Subcritical Clusters of 2.35 Wt% and 4.31 Wt% 235U Enriched UO2 Rods in Water with Steel Reflecting Walls
- Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)
A series of criticality experiments with 2.35 wt% and 4.31 wt% 235U enriched UO{sub 2} rods in water were performed to provide well defined benchmark type data on the effects of thick steel reflecting walls. For each fuel enrichment. the critical separation between three subcritical fuel clusters was observed to increase as 178.5 mm thick reflecting walls of reactor grade steel was moved towards the fuel. This increase was observed for fuel clusters having an undermoderated water-to-fuel volume ratio of 1.6 and for fuel clusters having near optimum neutron moderation (2.92 for the 2.35 wt% 235U enriched fuel and 3,88 for the 4.31 wt% 235U enriched fuel). In all cases the critical separation between fuel clusters increased to a maximum as the steel walls were moved towards the fuel clusters. This maximum effect was observed with about 10 mm of water between the fuel clusters and the steel reflecting walls. As this water gap was decreased, the critical separation between the fuel clusters also decreased slightly. Measurement data were also obtained for each enrichment with neutron absorber plates between the fuel clusters having the l .6 water-to-fuel volume ratio. During these measurements, the steel reflecting walls were at the near optimum distance from the fuel clusters. The fixed neutron absorbers for which data were obtained include 304-L steel, borated 304-L steel, copper, copper containing 1 wt% cadmium, cadmium, and two trade name materials containing boron (Boral and Boroflex), A comparison between these data and data from previous experiments indicates a slight reduction in the effectiveness of the absorber plates when the steel reflecting walls are present.
- Research Organization:
- Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)
- Sponsoring Organization:
- USNRC; USDOE National Nuclear Security Administration (NNSA), Nuclear Criticality Safety Program (NCSP)
- DOE Contract Number:
- AC06-76RL01830
- OSTI ID:
- 1079983
- Report Number(s):
- NUREG/CR-1784; PNL--3602
- Country of Publication:
- United States
- Language:
- English
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Technical Report
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Mon Jun 30 20:00:00 EDT 1980
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OSTI ID:958674
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
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Mon Nov 30 23:00:00 EST 1981
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OSTI ID:1083949
Criticality experiments with subcritical clusters of 2. 35 wt % and 4. 29 wt % /sup 235/U enriched UO/sub 2/ rods in water with uranium or lead reflecting walls
Technical Report
·
Wed Feb 28 23:00:00 EST 1979
·
OSTI ID:6165447