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Languages : en
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Book Description
The lifetime of a B/sub 4/C-in-tubes'' control rod may be limited by either nuclear worth depreciation or internal gas pressure buildup as helium is formed and released from the B/sub 4/C particles. Nuclear life is enhanced by thin tube walls for any given O.D. of tubing and by high B/sub 4/C density, but the time to failure from gas pressure buildup is increased by the opposite. The optimum B/sub 4/C density and tube wall thickness were calculated for maximum control rod life, using several release fractions of generated helium and a number of allowable cladding stress values. It was estimated that lifetimes of l0 or more years for B/sub 4/C-in-tubes control systems are achievable through the proper selection of tubing material and B/sub 4/C density values. The B/sub 4/C densities required for maximum lifetimes are in a range that can be obtained by vibratory compaction followed by swaging. (auth).