In September, we reported that tritium levels in one groundwater testing well at Pilgrim was trending higher – well #216 (4,882-5,307 picocuries per liter (pCi/L) were recorded in August). This was based on the Massachusetts Department of Public Health’s (DPH) September groundwater testing report. Read our September 19th blog about the issue.

DPH’s October report shows the same problem. Well #216 is continuing to trend higher than the other wells (3,330 – 5,720 pCi/L was recorded in September). In addition, tritium levels in wells #209 and #211 are also trending higher (797 – 1,350 pCi/L).

One of the possible sources cited in both reports is a leak resulting from a separated “neutralization sump discharge line” – basically a break in an underground line leading to the discharge canal. The leak reportedly started in April 2013, and it could be the reason for increased tritium levels in the nearby groundwater monitoring wells.

The October DPH report also discusses soil samples that were taken as part of the “neutralization sump discharge line” investigation. Although final results are still not available from Entergy (the samples were taken three months ago), preliminary results show that tritium is present in the soil. The question that still has not been answered is just how much tritium is present.

Soil tests done by the Massachusetts Environmental Radiation Laboratory (MERL; MERL and Entergy split some of the water and soil samples for testing) show cobalt-60 and cesium-137 at levels above normal. These hazardous isotopes release radiation, and are being found at relatively high levels on the Pilgrim site. Cesium-137 in particular is an extremely problematic fission product because it spreads easily in the environment due to its high water solubility.

MERL found 1,150 pCi/kg of cobalt-60 and 2,490 pCi/kg of cesium-137. The EPA Maximum Contaminant Levels for these radioisotopes equals 100 pCi/L and 200 pCi/L, respectively.

DPH’s report states that it is “unlikely” that these contaminants have migrated beyond the general area of the neutralization sump discharge line break. However, it doesn’t appear that soil testing has been done further from this one location. The DPH report does state, however, that the presence of cobalt and cesium is reason for further investigation and remediation of the potential source(s), especially since only tritiated water was reported in the past.

Entergy plans to install new testing wells in the month of November, and transducers – or monitors – are being considered for wells. In addition, Entergy is supposed to take additional soil samples from the area of the neutralization sump discharge line break (near well #216) in order to better characterize the soil and groundwater contamination.

Stay tuned for those results.