Status report for inactive miscellaneous underground storage tanks at Hanford Site 200 Areas

The purpose of this status report is to summarize updated data and information from the FY 1994 strategy plan that is associated with inactive miscellaneous underground storage tanks (IMUSTs). Assumptions and processes to assess potential risks and operational concerns are documented in this report. Safety issue priorities are ranked based on a number of considerations. Sixty-three IMUSTs have been Identified and placed on the official IMUST list. All the tanks are associated with past Hanford Site operations. Of the 63 tanks., 19 are catch tanks, 20 are vault tanks, 3 are neutralization tanks, 8 are settling tanks, 2 are solvent makeup tanks used to store hexone, 2 are flush tanks, 3 are decontamination tanks, 1 is a diverter station, 1 is a receiver tank, 1 is an experimental tank, and 3 are waste handling tanks. It is important to proactively deal with the risks Imposed by these 63 tanks, and at the same time not jeopardize the existing commitments and schedules for mitigating and resolving identified safety issues related to the 177 SSTs and DSTS. Access controls and signs have been placed on all but the three official IMUSTs added most recently. An accelerated effort to identify authorization documents and perform unreviewed safety question (USQ) screening has been completed. According to a set of criteria consistent with the safety screening data quality objective (DQO) process, 6 IMUSTs are ranked high related to the hydrogen generation potential safety Issue, 1 is ranked high related to the ferrocyanide potential safety issue, 6 are ranked high related to the flammability potential safety issue, and 25 are ranked high related to the vapor emissions potential safety issue