The magnitude and relevance of the February 2014 radiation release from the Waste Isolation Pilot Plant repository in New Mexico, USA

摘要

After almost fifteen years of successful waste disposal operations, the first unambiguous airborne radiation release from the Waste Isolation Pilot Plant (WIPP) was detected beyond the site boundary on February 14, 2014. It was the first accident of its kind in the 15-year operating history of the WIPP. The accident released moderate levels of radioactivity into the underground air. A small but measurable amount of radioactivity also escaped to the surface through the ventilation system and was detected above ground. The dominant radionuclides released were americium and plutonium, in a ratio consistent with the known content of a breached drum. The radiation release was caused by a runaway chemical reaction inside a transuranic (TRU) waste drum which experienced a seal and lid failure, spewing radioactive materials into the repository. According to source-term estimation, approximately 2 to 10 Ci of radioactivity was released from the breached drum into the underground, and an undetermined fraction of that source term became airborne, setting off an alarm and triggering the closure of seals designed to force exhausting air through a system of filters including high-efficiency-particulate-air (HEPA) filters. Air monitoring across the WIPP site intensified following the first reports of radiation detection underground to determine the extent of impact to WIPP personnel, the public, and the environment, if any. This article attempts to compile and interpret analytical data collected by an independent monitoring program conducted by the Carlsbad Environmental Monitoring & Research Center (CEMRC) and by a compliance-monitoring program conducted by the WIPP's management and operating contractor, the Nuclear Waste Partnership (NWP), LLC., in response to the accident. Both the independent and the WIPP monitoring efforts concluded that the levels detected were very low and localized, and no radiation-related health effects among local workers or the public would be expected.