INCORPORATION OF AN "UNREVIEWED SAFETY QUESTION" AND OTHER NUCLEAR REGULATORY REQUIREMENTS INTO A CERCLA CHARACTERIZATION PROCESS

This paper describes the integration necessary between the regulations and orders of different federal agencies during the environmental waste site characterization and remediation of a tank in western Washington. The environmental cleanup activities at the U.S. Department of Energy’s (DOE) Hanford Nuclear Reservation are formalized through a Federal Facilities Compliance Act Consent Order, the Hanford Federal Facility Agreement and Consent Order (Ecology et al. 1994) referred to as the Tri-Party Agreement or TPA. At Hanford, cleanup activities are performed under the authority of the order to comply with Comprehensive Environmental Response, Compensation and Liability Act of 1980 (CERCLA) and the Resource Conservation and Recovery Act of 1976 (RCRA) corrective action program. Nuclear safety issues are incorporated into CERCLA/RCRA activities as appropriate. Generally, waste sites with Nuclear Safety concerns are incorporated into the associated facility authorization basis. Sometimes, however, nuclear safety issues and the analysis they require take precedence over CERCLA/RCRA authorities. The nuclear safety issues associated with Hanford’s Plutonium Finishing Plant (PFP) settling tank 241-Z-361 is the example discussed in this paper. During a chemical hazards’ review at the PFP facility, it was discovered that settling tank 241-Z-361 was not evaluated as part of the PFP authorization basis as required by DOE Order 5480.21. The tank was used as a settling tank for plutonium containing wastes discharged from the PFP facility during the process of extracting plutonium from spent nuclear fuel. The potential hazards presented by the tank were so significant, that the attention and concern of several agencies was immediately expressed. An Unreviewed Safety Question (USQ) was declared immediately and the hazards presented by the tank and its contents were analyzed using set criteria of nuclear and worker safety criteria. An authorization basis was developed for the tank. This document is called a Justification for Continued Operations (JCO) and was mandated by DOE before any CERCLA activities could be initiated. The hazards identified for the tank included the risk of a criticality event (uncontrolled nuclear reaction resulting in high radiation), an explosion due to the combination of chemicals in the tank, a collapse of the tank because of diminished structural integrity, and a possible deflagration due to hydrogen buildup within the tank.