TANK FARM CLOSURE - A NEW TWIST ON REGULATORY STRATEGIES FOR CLOSURE OF WASTE TANK RESIDUALS FOLLOWING NUREG

Waste from a number of single-shell tanks (SST) at the U.S. Department of Energy's (DOE) Hanford Site has been retrieved by CH2M HILL Hanford Group to fulfill the requirements of the 'Hanford Federal Facility Agreement and Consent Order (HFFACO) [1]. Laboratory analyses of the Hanford tank residual wastes have provided concentration data which will be used to determine waste classification and disposal options for tank residuals. The closure of tank farm facilities remains one of the most challenging activities faced by the DOE. This is due in part to the complicated regulatory structures that have developed. These regulatory structures are different at each of the DOE sites, making it difficult to apply lessons learned from one site to the next. During the past two years with the passage of the Section 3116 of the 'Ronald Reagan Defense Authorization Act of 2005' (NDAA) [2] some standardization has emerged for Savannah River Site and the Idaho National Laboratory tank residuals. Recently, with the issuance of 'NRC Staff Guidance for Activities Related to US. Department of Energy Waste Determinations' (NUREG-1854) [3] more explicit options may be considered for Hanford tank residuals than are presently available under DOE Orders. NUREG-1854, issued in August 2007, contains several key pieces of information that if utilized by the DOE in the tank closure process, could simplify waste classification and streamline the NRC review process by providing information to the NRC in their preferred format. Other provisions of this NUREG allow different methods to be applied in determining when waste retrieval is complete by incorporating actual project costs and health risks into the calculation of 'technically and economically practical'. Additionally, the NUREG requires a strong understanding of the uncertainties of the analyses, which given the desire of some NRC/DOE staff may increase the likelihood of using probabilistic approaches to uncertainty analysis. The purpose of this paper is to discuss implications of NUREG-1854 and to examine the feasibility and potential benefits of applying these provisions to waste determinations and supporting documents such as future performance assessments for tank residuals