Evaluation of strontium-90 radial concentration profiles in Peach Bottom HTGR Core 2 fuel elements. HTGR base technology program, HTGR chemistry studies (189a 01329). [483 2000]
Description: Radial concentration profiles of /sup 90/Sr were evaluated for four fuel elements of the Peach Bottom High-Temperature Gas-Cooled Reactor (HTGR) Core 2. A transport model utilizing a single effective diffusion coefficient was able to reproduce the strontium concentraion profile in graphite at temperatures above about 960/sup 0/C. Below this temperature, ''tails'' were observed in the experimental concentration profile and the profiles could not be completely reproduced. Diffusion coefficients determined from the study were slightly below those used in current reference HTGR design calculations. Experimental data exhibited a relatively high concentration at the graphite surfaces. Data and analyses are presented which indicate this may be due to a spatial variation in graphite properties resulting from an inhomogeneous distribution of the graphite impregnant. Unlike earlier Peach Bottom Core 1 studies the /sup 90/Sr precursor contribution to the total /sup 90/Sr concentration profile was determined to be negligible for these Core 2 data, apparently due to the much lower fuel partial coating failure fraction in Core 2. The calculated /sup 90/Sr released from the core is less than that measured, but the amount released is well below the amount established by design criteria.
Date: February 1, 1979
Creator: Haire, M.J.
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