Status of tank 241-SY-101 data analyses

The Waste Tank Flammable Gas Stabilization Program was established in 1990 to provide for resolution of a major safety issue identified for 23 of the high-level waste tanks at the Hanford Site. The safety issue involves the production, accumulation, and periodic release from these tanks of flammable gases in concentrations exceeding the lower flammability limits. This document deals primarily with tank 241-SY-101 from the SY Tank Farm. The flammable gas condition has existed for this tank since the tank was first filled in the time period from 1977 to 1980. During a general review of waste tank chemical stability in 1988--1989, this situation was re-examined and, in March 1990, the condition was declared to be an unreviewed safety question. Tank 241-SY-101 was placed under special operating restrictions, and a program of investigation was begun to evaluate the condition and determine appropriate courses of action. This report summarizes the data that have become available on tank 241-SY-101 since it was declared as an unreviewed safety question and updates the information reported in an earlier document (WHC-EP-0517). The report provides a technical basis for use in the evaluation of safety risks of the tank and subsequent resolution of the unreviewed safety question