The Radiochemistry Unit (RCU) of DWRLB is the only State laboratory capable of conducting radiological testing on environmental samples. As the primary drinking water laboratory for the State of California, RCU is certified by the USEPA to test all regulated radioactive contaminants. Drinking water is tested for three types of radiation (alpha, beta and gamma) to determine compliance with the Safe Drinking Water Act regulations under the Radionuclides Rule.
RCU supports the Radiologic Health Branch in monitoring environments surrounding the nuclear power plant sites in California (San Onofre and Diablo Canyon). Water, air, milk, soil, sediment, vegetation and biota are analyzed for fission products which can reveal accidental releases. RCU also monitors air samples throughout the State for ambient radiation. Air sampling stations are located in Eureka, Diablo Canyon, Livermore, Long Beach, Richmond, San Diego, San Luis Obispo, and San Onofre. Weekly air samplings detect airborne radionuclides that could be released anywhere around the globe, for example, elevated radioactivity was measured for six weeks after the Chernobyl accident in 1986, and also after the Tokaimura (1999) and Fukushima (2011) incidents.
Another major area of work is enforcement/compliance and decommissioning/decontamination. Radioactive materials are used widely in manufacturing, research and hospitals throughout California, and these facilities require periodic testing for surface contamination. As sites are decommissioned, analyses of environmental samples are performed to demonstrate that radioactivity does not exceed background levels before these sites are released for unrestricted use. Currently samples from the former military sites of Treasure Island, Hunters Point Shipyard, McClellan Air Force Base, Alameda Naval Station and Mare Island are being tested by RCU.
RCU is part of California's Nuclear Power Plant Emergency Response Program (NPPERP). In this capacity, RCU will receive environmental samples during the re-entry phase of a nuclear incident. Following such an incident initial field monitoring will be conducted by Federal agencies. If necessary, RCU could receive contaminated environmental samples for analysis. RCU is equipped with a special Semi-Hot Laboratory where moderately radioactive samples can be handled.
Research and method development is an important part of RCU's activities. Achievements in this area include the development of methods for the detection of lead-210 and polonium-210 in water sources, the detection of gross alpha and gross beta activities in water by liquid scintillation spectroscopy, improvements in measuring radon in ground water and a comprehensive survey of the occurrence of radioactive elements (e.g., radium, uranium) in California's groundwater wells.