Measurement of high energy gross beta and K-40 by Cerenkov counting in liquid scintillation analyser

The Environmental Survey Laboratory is responsible for the monitoring of ra dioactivity due to natural and artificially produced radionuclides in a var iety of samples available around the nuclear facilities at Tarapur. Standar d methods of radiochemical separation and counting are followed to determin e beta-emitters in various matrices. To make the measurement simple and det ect lower levels of contamination in some of the matrices, a method was dev eloped to measure the high energy gross beta-activity primarily due to Y-90 in borehole water and urine samples of occupational workers by Cerenkov co unting in a liquid scintillation analyser. Cerenkov counting results of bor ehole samples were compared with thr total gross P-activity measured by a l ow background beta-counter. The combined measurements were used to evaluate Sr-90 and Cs-137 levels without chemical separation or gamma-spectrometry. Cerenkov counting technique was also utilised to evaluate K-40 in drinking water and intercomparison water samples. The paper presents the methodolog y and results of a few measurements using the technique.