Resolution of Generic Safety Issues: NMSS-0014. Surety Estimates for Groundwater Restoration at in Situ Leach Facilities (Rev. 1) ( NUREG-0933, Main Report with Supplements 1–34 )
This issue was identified1723 by NMSS to pursue research to provide a methodology to calculate surety for groundwater restoration activities at in situ leach uranium extraction facilities and a post-restoration groundwater quality stability monitoring methodology. The following tasks were envisioned: (1) review approaches used to estimate pore volumes and to calculate surety amounts and obtain data to evaluate these approaches; (2) develop a pore volume estimation methodology and document it in a NUREG report; (3) develop cost estimation methodology for use in evaluating the level of financial surety required; (4) brief regulators on the surety methodology; (5) review the existing approaches used to determine an appropriate time period for post-restoration monitoring period and obtain datasets to evaluate the methodologies; (6) use the datasets to develop and test the methodologies; (7) develop a robust methodology; and (8) transfer the methodology to regulators through briefings and a NUREG report.
This issue was given a medium priority ranking and resolution was pursued.1723 The staff's work resulted in the publication of NUREG/CR-68701892 which provides a useful perspective on the costs associated with groundwater restoration at in-situ leach facilities, and describes several methods for estimating these costs at new facilities, including a rigorous approach for development of a site-specific model that considers groundwater flow, solute transport, and geochemical reactions in the uranium ore zone of interest. With this modeling approach, groundwater restoration volumes and, correspondingly, their associated costs, can be estimated. As such, NUREG/CR-68701892 provides the methodology originally requested by the Uranium Recovery Program. Thus, the issue was resolved with no new requirements or guidance for licensees.1893