O. V. Mykhailov1,
A. K. Terzi2
1 Institute for Safety Problems of Nuclear Power Plants, NAS of Ukraine, 36a, Kirova st., Chornobyl, 07270, Ukraine,
2 State Specialized Enterprise “Chornobyl NPP”, Slavutych, 07101, Ukraine
The composition and features of radionuclide contamination of solid radioactive waste (SRW) stored in the western “light” compartment of SRW repository (RSRW) of the SSE “Chornobyl Nuclear Power Plant” (ChNPP) were studied. Representative samples of SRW taken from the top layer of materials at 1-m depth were split into four streams, and according to their physical state, they were classified into two categories: combustible (one stream) and non-combustible (three streams) ones. After relevant sample preparation was carried out, the SRW samples were investigated in the ChNPP Laboratory for water-radiochemical measurement in order to identify the radionuclides, which are subject to compulsory certification according to SRW acceptance criteria valid in the Exclusion Zone. It was stated that SRW radioactivity levels in the upper layer of western “light” compartment of SWR are, mainly, determined by radionuclide contents of 137Cs, 60Co, 90Sr, 94Nb, 235U, 238U, 241Am, 3 H and 14C. The parameters of regression dependencies and correlation coefficients between the specific activity of radionuclides in stream- and integrated (for non-combustible SRW) data samples compiled of measurement results (above the minimally detectable activity) were estimated. It was stated that the features of radionuclide contamination spectrum of the SRW in western and eastern compartments are largely similar ones, that, apparently reflects the typical properties of the ChNPP operational wastes produced in period from 1978 to 1986, and which had been stored in mothballed state in the RSRW before the accident at the ChNPP Unit 4 occurred. However, for such radionuclides as 60Co, 94Nb and 90Sr, observable levels of SRW contamination in the western compartment are significantly higher, than in the eastern one. At the same time, the specific activity of uranium isotopes 235, 238U is several times lower. It was concluded that the experimental and analytical results obtained in this work can be used as the source data for the next stage of studies — calculation of scaling
factors and determination of radionuclide vectors needed to certify the difficult-to-measure radionuclides in the ChNPP SRW packages being transported to their burial.
Keywords: Chornobyl NPP, solid radioactive waste, specific activities, difficult-to-measure radionuclides, key nuclides, correlation factor, scaling factor
1. Criteria for acceptance of waste for burial in specially equipped near-surface repository for solid radwaste (SESRSRW). First stage of SESRSRW operation. Acceptance of RAW from SSE “ChNPP” PTLRW and PTSRW for burial in two symmetrical compartments of SESRSRW. Revision 5. Endorsed by acting Director General of State Corporation “UkrSE ‘Radon’”. Chornobyl, 2009. 38 p. (in Ukr.)
2. Decision on conducting the 3rd stage of “hot” tests and the initial stage of industrial operation of the ICMSRW. Conclusion of the State examination of nuclear and radiation safety of the SSE ChNPP documentation. Approved by T. P. Kilochytska, Deputy Chairman of State Nuclear Regulatory Inspectorate of Ukraine (SSE “ChNPP”, Archive inv. No. 28 dated July 28, 2016). (in Ukr.)
3. RAW management, radiation safety. Chornobyl NPP (September 12–16, 2016). Report of Technical Support Mission. Moscow: WANO-MC, 2016, 10 p. (TSM43-2016) (in Russ.)
4. Methodology and practice in defining nuclide vectors. Final report of WANO-MC Technical Support Mission at Chernobyl NPP (Slavutych, May 14–18, 2018). Slavutych, 2018,
12 p. (in Russ.)
5. IAEA (2007). Strategy and methodology for radioactive waste characterization. IAEA-TECDOC-1537. Vienna: IAEA, 182 р.
6. IAEA (2009). Determination and use of scaling factors for waste characterization in NPP. IAEA Nuclear Energy Series NW-T-1.18. Vienna: IAEA, 142 р.
7. Mikhailov A. V., Pavliuchenko N. I., Miasnikov A. V., Terzi A. K. (2019). [Results of radionuclide vectors determination to be used in characterization of SSE NPP’s solid radwaste]. Problems of Chornobyl Exclusion Zone, vol. 20, pp. 13–26. (in Russ.)
8. Mykhailov O. V., Bezmylov V. M., Terzi A. K. (2020). Analysis of radionuclide contamination features in solid radwaste of “light” eastern compartment of solid waste repository of Chornobyl NPP. Nuclear Power and the Environment, vol. 16, no. 1, pp. 40–48.
9. Grubbs F. E. (1969). Procedures for detecting outlying observations in samples. Technometrics, vol. 11, no. 1, pp. 1–21.
10. Ross S. M. (2004). Introduction to probability and statistics for engineers and scientists. Third Edition. USA: Elsevier Academic Press, 641 p
If the article is accepted for publication in the journal «Industrial Heat Engineering» the author must sign an agreement on transfer of copyright. The agreement is sent to the postal (original) or e-mail address (scanned copy) of the journal editions.
Authors retain copyright and grant the journal right of first publication with the work simultaneously licensed under a Creative Commons Attribution License International CC-BY that allows others to share the work with an acknowledgement of the work’s authorship and initial publication in this journal.