PUMPING MONITOR WELLS FOR EARLY DETECTION MONITORING AT NUCLEAR FACILITIES

The need for new nuclear facilities is anticipated, whether for new power generating plants or for waste storage from existing plants. The evaluation of potential contaminant releases to the environment needs to be considered for these facilities. Releases typically occur as small, persistent leaks that go undetected for long periods of time, creating plumes that spread until detected by monitor wells. Early detection systems are essential to minimize the spread of contamination. The key to early recognition of a problem is detecting the plume near the source soon after release. Unfortunately, near the source plumes are often thin and difficult to detect due to short transport distances that limit mixing. As the plume migrates from the facility, it spreads making it more likely to be detected by monitoring wells. The difficulty in locating monitor wells is compounded by uncertainty and the variability of groundwater flow and contaminant transport in the subsurface.

An active system that continuously pumps water from one or more monitor wells near the facility is proposed and evaluated with modeling. A pumping monitor well creates a large capture zone, both vertically and horizontally, increasing the likelihood of capture and detection. The principal contaminants of concern at nuclear facilities are radionuclides, which can be detected at low concentrations, minimizing the concern of dilution due to pumping. Early detection of mobile contaminants through pumping could allow problems to be identified and mitigated, minimizing efforts associated with remediating a large plume of multiple contaminants. The benefit of an active system is demonstrated by modeling results of a tritium plume emanating from the high flux beam reactor (HFBR) at Brookhaven National Laboratory.

Data and background information on the HFBR tritium plume were generously provided by Brookhaven National Laboratory and the Department of Energy. Funding for this project was provided by the Nuclear Regulatory Commission.