Solute Concentration in SSS Storage Tanks: Basis for Gd(NO Sub 3 ) sub 3 Center DOT 6H sub 2 O Concentration Requirement in 100 Area Technical Standard 3.04

摘要

The value of 0.34 gm/cm sup 3 for the minimum ink solute concentration is devised to protect the validity of the current applicable, generic Confinement Protection Limit (CPL) calculations. These CPL's are based on AA3 code accident calculations that use a table of measured delta k/sub eff/'s versus time following an ink injection triggered by the Automatic Backup Shutdown - Safety Computer (ABS-S/C) system. The measured ink worth versus time is based on a test of the SSS system that occurred in January 1975. An analysis of the available data has established that the ink solute concentration during the 1975 test was 0.34 gm/cm sup 3 (best estimate) within an uncertainty of +-0.07 gm/cm sup 3 . No greater accuracy in this estimate is necessary because the ink worth during the important early phases of postulated accidents is rather insensitive to the ink solute concentration. Calculations have shown that a 25% reduction in the solute concentration will cause only a 2% reduction in the ink worth at times less than 10--15 seconds after the SSS is triggered. Current procedures for mixing the ink will generate a solute concentration between 0.35 and 0.37 gm/cm sup 3 . A previous recommendation to change the procedure by which ink is mixed to allow an acceptance band between 0.37 and 0.53 gm/cm sup 3 is consistent with setting the Technical Standard minimum at 0.34 gm/cm sup 3 . 8 refs., 3 tabs. (ERA citation 13:056627)