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Title: Nuclear heating in He-3 fast SCRAM rods

Technical Report ·
DOI:https://doi.org/10.2172/6975970· OSTI ID:6975970

Nuclear heating occurs in the He-3 fill gas of the fast SCRAM rods as a result of the very neutron captures which make the rods operative. This heating gives rise to a pressure rise within the rod. If severe enough this heating could present a structural problem, but more importantly the pressurization always causes a partial backflow of the fill gas. This, in turn, reduces the residual gas content and thus reduces the effectiveness of the rod. If enough gas were expelled, the rod would no longer have the required reactivity shutdown margin. This memorandum discusses the bases for determining the heat input and estimating the resultant temperatures, pressures, and backflows to be expected under various assumed design and operational conditions. A method for mitigating the effect by means of heat-conducting fins on the interior surface of the rods is discussed and evaluated. 5 refs.

Research Organization:
Savannah River Site (SRS), Aiken, SC (United States)
Sponsoring Organization:
DOE/DP
DOE Contract Number:
AC09-89SR18035
OSTI ID:
6975970
Report Number(s):
WSRC-RP-89-770; ON: DE90009302
Country of Publication:
United States
Language:
English