During the week, from May 14 to May 18, the technical support mission of the World Association of Nuclear Operators (hereinafter: WANO) devoted to review the methodology and practice for the nuclide vectors identification was held at Chernobyl NPP.
The timeliness of the topic discussed within the mission is caused by presence of difficult-to-measure radionuclides in the radioactive waste (hereinafter: RAW) of Chernobyl NPP. ChNPP intends to assess their activity by combining the measurement of the key radionuclides activity directly and calculation of the difficult-to-measure radionuclides activity using a predetermined scaling factor, that is, by the nuclide vector method.
This topic is important for ChNPP in two aspects. The first aspect is related to the commissioning of the Industrial Complex for Solid Radioactive Waste Management (hereinafter: ICSRM). The problem was identified in 2015 during the Phase II of ICSRM commissioning. Based on the testing results it was revealed that the activity of a number of nuclides, in particular, U, Pu, Am, is assessed incorrectly by the existing radiation and technological control system, and, as a result, that doesn’t allow to draw up the corresponding passport for the Radioactive Waste package.
The second aspect of the problem is linked with the project activity to create a facility for materials release from regulatory control, implementing under support of the European Commission. To obtain reliable results regarding difficult-to-measure radionuclides it is also necessary to use the nuclide vector method.
Thus, the problem of the lack of valid methods of the nuclide vectors identification for ChNPP’s radioactive materials characterization raises problems regarding two streams of radioactive materials at Chernobyl NNPP: firstly, creates a problem of RAW characterization at the Solid Radwaste Processing Plant, and secondly, for characterization of radioactive materials at the facility for materials release from regulatory control.
Invited by WANO Experts from Ignalina NPP (Lithuania), Kozloduy NPP (Bulgaria), Mochovce NPP (Slovakia), presented their experience in solving similar problems and technologies used at their sites. Representatives from Ukrainians NPPs, NNEGC "Energoatom", SSTC NRS, SSRI "Chernobyl Center for Nuclear Safety, Radioactive Waste and Radioecology", as well as NPPs Safety Problems Institute joined the mission.
Recommendations will be developed based on the mission results, which will be used during the relevant works implementation at the ChNPP.
