Study on coincidence and anti-coincidence -ray spectrometry for the rapid radioactivity evaluation of solidified products prepared from radioactive wastes

Haraga, Tomoko ; Kameo, Yutaka; Hoshi, Akiko; Yonezawa, Chushiro*; Nakashima, Mikio

Non-destructive -ray spectrometry has been examined as a simple and rapid radioactivity measurement technique for the solidified products prepared by plasma melting for low level radioactive miscellaneous wastes generated from nuclear facilities. The Compton background resulting from the coexisting radionuclides pose a problem in the usual -ray spectrometry which uses only a Ge detector. In order to reduce the background count and to measure the interested nuclide selectively, the coincidence and the anti-coincidence -ray spectrometry using the Ge-BGO detector system were examined. As a result of applying the anti-coincidence -ray spectrometry to a single -ray emitter Cs and the coincidence -ray spectrometry to multiple -ray emitter Eu under existence of Co, the detection limits of Cs and Eu in the sample, which contained Co, were reduced by a factor of about 6 and 1.5, respectively. It was confirmed that the present methods are useful for the -activity measurement of solidified products.