As the number of NPP energy units grows, and the old ones are shut down, energy workers face the questions of burnup fuel utilization and, in particular, the optimization of choice of the type of radioactive waste disposal. For effective sorting out of radioactive waste the level of activity of radioactive waste should be determined the right way. For such purposes gamma spectrometers with good energy resolution, allowing determine components and concentration of separate radionuclides in each sample, are used.

Currently there is a diversity of detectors which register gamma radiation. They differ in their working modes, the way of production, conditions of work and have different energy resolutions. It should be resistant to vibrations, acoustic noises, have appropriate size corresponding with the parametres of the construction.

Fig. 1. Scheme of the facility for sorting radioactive waste

Xenon is the most effective working substance for creation of modern gamma detectors on the basis of inert elements. MEPhI Radiation laboratory of experimental physics and cosmophysics (№7) 5^th year student Evgeniy Petkovich (research supervisor – Cand.of Phys.-Math. Sciences, Professor V.V. Dmitrienko) has worked out a xenon gamma spectrometer on the basis of thinwalled 4-liter xenon gamma detector for a facility on sorting and segregation of radioactive waste. “With the help of xenon gamma spectrometer it is possible to get energy resolution of about 2 % for gamma quantums with energy of 1 MeV. Besides, such detector is less production-consuming, it is possible to create it in different sizes. Such spectrometer can work even in field conditions”, - Evgeniy Petkovich commented on his invention.

As the young scientist claims, during the creation of the spectrometer a system of transition of spectrometer information through RS-485 interface has been worked out, xenon gamma spectrometer has been tested in laboratory conditions, and the possibility of detection and identification of radionuclides has been tested. The research has shown that 137Cs source with the activity of ~ 9 kBq can be detected and identified by the xenon gamma spectrometer at 5 cm distance from detector for 5-10 sec. The xenon gamma spectrometer’s command performance («bad» or «good») has also been tested.

Fig. 2. Identification of radionuclides 137Cs