MODELING AND MONITORING BASIS FOR TRITIUM PLUME MANAGEMENT STRATEGIES AT BROOKHAVEN NATIONAL LABORATORY

In 1997, a tritium plume was discovered emanating from beneath the High Flux Beam Reactor (HFBR) building at Brookhaven National Laboratory (BNL) in Upton, Long Island, New York. The plume was determined to be approximately 4,200 feet long. The source of the plume was a 12-year-old leak in the reactor's spent fuel pool (SFP). This source of groundwater contamination was removed in December 1997 when the pool was drained.

While plans were being developed to remediate the tritium plume, the Princeton Avenue Interim Remedial Action (IRA) was implemented at the leading edge of the plume to prevent it from migrating beyond Princeton Avenue. The IRA system went into operation in May 1997 and was transferred into a standby mode in September 2000 when it was demonstrated that the plume concentrations were lower than specific action levels specified in the Record of Decision.

Groundwater model simulations forecasted that the tritium plume would radioactively decay and disperse in the aquifer to activities much less than drinking water standards before leaving the BNL site. The model projections also indicated that the plume leading edge would not grow significantly from the 1997 extent mapped as part of the Operable Unit III Remedial Investigation. Because of these projections and because there is no applicable treatment for environmental tritium concentrations, the primary means selected in the OU III Feasibility Study Report to remediate the tritium plume was natural attenuation with extensive monitoring and reporting, combined with limited groundwater extraction in response to specific contingencies.

Since September 2000, several contingencies have been activated to manage the natural attenuation of the tritium plume on the BNL property. As of 2006 this strategy of plume management by natural attenuation has met all ROD requirements at minimal cost to BNL and to the satisfaction of all stakeholders