Cistern barrels. and groundwater samples were collected in 5- are 15-gal oor The 15-gallon water samples were acidified in the sid, and = 3 Water samples were returned to LLNL for analysis of !3/cs, 90s-. ang 239-24c04u. ANALYTICAL METHODS AND QUALITY CONTROL A brief description of our analytical methods and quality -antrol program is given here. More details are given in Jennings and Mount (~283). The LLNL gamma-counting facility #$ housed in a specials construczed building. The floor is a 9-inch-thick layer of concrete with <"ack serpentine as the aggregate. This rests on a 12-inch layer of black serzantine. This serpentine was used because it’ contains very small amounts <- naturally occurring radionuclides. The walls and ceiling are extremely well insulated to maintain constant temperature. The room containing the comuter and the analyzer electronics has its own temperature and humidity-contrs: system. There are currently 16 Ge(Li), p- and n-type, detectors in use. They are housed in steel caves made from selected materials and are spaces to eliminate any interaction of signals among adjacent detectors. High-volzage and power cables are run separately from the signal cables to minimize zny possible interference. : Three Canberra analyzers are used to collect the spectra. 4096-channel spectra are written to 1600-bpi 9-track tape. The . The spectra are reduced using the program GAMANAL (Gunnink and Niday, 1972) znd a Cray computer. The resulting numbers are then entered into various cata bases. A standard containing !33pa, 137cs, and ©9Co is counted on each detector each day to provide an ongoing calibration record. Any counter that exhibits #0.5-channel difference from the standard channel location is acjusted back to the proper channel. fach Monday, the same standards 80 minutes and a background is counted overnight. are counted for These data ave processed by GAMANAL like any other sample and are entered into a data base. This allows - an experimenter to access the whole history of the detector. Gamma spectroscopy for !37cs and other gamma-emitting raconuclides is performed primarily at LLNL. Sometimes, when our sample load is particularly heavy, we have other laboratories perform gamma-spectroscopy aralyses for us. All of our detectors have been calibrated and cross-checked fcr '3?cs and 41am with detectors at three other laboratories. 9000313 Blind dug icates and