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Title: Temperature coefficients of reactivity for the SRS Mark 22 assembly

Conference · · Transactions of the American Nuclear Society; (United States)
OSTI ID:6680830
;  [1]
  1. Westinghouse Savannah River Co., Aiken, SC (United States)

The nuclear reactors at the Savannah River Site (SRS) are unique in design and operation. In contrast to commercial power reactors, the SRS reactors were designed for isotope production rather than power generation. The SRS reactors are cooled and moderated by heavy water at near-atmospheric pressure, and the fuel assemblies consist of concentric annualar tubes rather than the solid pins typically found in power reactors. These and other factors make the neutronic behavior of SRS reactors unique. Temperature coefficients of reactivity are a measure of the change in core reactivity resulting from a change in the temperature of the reactor components. These coefficients are used in safety analyses and for prediction of reactivity changes with control rod moves during reactor operations. This paper presents the results of an investigation of temperature coefficients for the Mark 22 assembly currently charged to the K Reactor. The Mark 22 assembly is the tritium-producing assembly currently in use at SRS. This assembly contains two concentric fuel tubes of enriched uranium-aluminum alloy located between two concentric target tubes of lithium-aluminum alloy. There are three active coolant channels (cooling both sides of each fuel tube) and two low-flow dead spaces at the center and outside of the assembly. Heavy water flows down the three coolant channels in the Mark 22 assemblies and then jets out into the moderator space (the heavy water region bewteen assemblies). Six regional temperature coefficients are calculated at SRS: fuel, target, coolant, dead space, moderator upflow, and moderator downflow. The first four coefficients correspond to regions of the assembly and are calculated using the GLASS infinite lattice transport code. The two moderator coefficients correspond to reactor core regions and are calculated using the GRIMHX three-dimensional finite lattice diffusion theory code. Assembly coefficients calculated by GLASS have been experimentally verified.

OSTI ID:
6680830
Report Number(s):
CONF-921102-; CODEN: TANSAO
Journal Information:
Transactions of the American Nuclear Society; (United States), Vol. 66; Conference: Joint American Nuclear Society (ANS)/European Nuclear Society (ENS) international meeting on fifty years of controlled nuclear chain reaction: past, present, and future, Chicago, IL (United States), 15-20 Nov 1992; ISSN 0003-018X
Country of Publication:
United States
Language:
English