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Title: Reactivity effects of moderator voids

Technical Report ·
DOI:https://doi.org/10.2172/6179318· OSTI ID:6179318

Reactivity worths for large moderator voids similar to those produced by steaming in postulated reactor transients were measured in the Process Development Pile (PDP) reactor. The experimental results were compared to the computed void worths obtained from techniques currently used in routine safety analyses. Neutron energy spectrum measurements were used to verify a modified lattice pattern that correctly computed the measured spectrum, and consequently, improved macroscopic cross sections. In addition, a special two-dimensional transport calculation was performed to obtain an axially defined diffusion coefficient for the void region. The combination of the modified lattice calculations and the axial diffusion coefficient yielded void reactivity worths which agreed very well with experiment. It was concluded that the computational modules available in the JOSHUA system (GLASS, GRIMHX) would yield accurate void reactivity worths in SLR--SRP safety analysis studies, provided the above mentioned modifications were made.

Research Organization:
Du Pont de Nemours (E.I.) and Co., Aiken, SC (United States). Savannah River Lab.
DOE Contract Number:
EY-76-C-09-0001
OSTI ID:
6179318
Report Number(s):
DP-1426; TRN: 79-010507
Country of Publication:
United States
Language:
English