O. V. Mykhailov, V. M. Bezmylov
Institute for Safety Problems of Nuclear Power Plants,
NAS of Ukraine, 36a, Kirova st., Chornobyl, 07270, Ukraine
DOI: doi.org/10.31717/2311-8253.23.1.3
Abstract
To ensure the safety of repositories used for final disposal of solid radioactive waste (SRW) of nuclear power plants and other nuclear installations, the compliance of their radionuclide contamination levels with valid acceptance criteria has to be monitored. Scaling factors (SF) are used in many world countries to quickly solve the problems with radiological characterization of SRW subject to burial. To ensure the reliability of SF application in different countries, episodic or periodic verification and update of SF values is conducted. The purpose of work is to substantiate the global experience of SF verification, which, according to the IAEA methodology, is used for certification of specific and total activity of difficult-to-measure radionuclides (DTM) in SRW batches destined for disposal. The work addresses the current state of SF methodology application, and analyzes the main steps of its implementation. It was stated that current IAEA recommends declare the need for their verification and update of previously established SFs only, without offering any clear algorithms for implementation of this procedure and terms of its realization. However, in practice, such a procedure is used for radiological characterization of SRW in order to ensure quality guarantees in obtaining information regarding their radiation and other characteristics. This work also examines in detail the experience in applying the SF verification on the examples of several world countries. It was concluded that the verification should be a needed element in ensuring the reliability of SF use for radiological characterization of SRW. The experience of verification by means of SF validation using quantitative criteria is summarized. An algorithm is defined, according to which, and based on obtained results, it is possible to come to a statistically justified decision regarding the further use of existing SFs or recognition of a need in their updating for radiological characterization of new batch of waste
Keywords: solid radwaste, difficult-to-measure radionuclides, specific activity, minimum detectable activity, scaling factor, verification.
1. Determination and use of scaling factors for waste characterization in NPP. IAEA Nuclear Energy Series NW-T-1.18. Vienna: IAEA, 2009, 142 р.
2. Mykhailov O. V., Krasnov V. O., Bezmylov V. M. (2019). Theoretical and practical aspects in using scaling factor method to characterize operational solid radioactive waste producible at nuclear power plants. Nuclear Power and the Environment, vol. 13, no. 1, pp. 52–58. (in Rus).
3. IAEA (2009). Classification of radioactive waste: safety guide. Vienna: IAEA. Available at: www-pub.iaea.org/mtcd/publications/pdf/pub1419_web.pdf.
4. IAEA (2003). Derivation of activity limits for the disposal of radioactive waste in near surface disposal facilities. IAEA-TECDOC-1380. Vienna: IAEA. doi.org/10.7733/jnfcwt.2020.18.4.517.
5. 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.)
6. Mykhailov O. V., Bezmylov V. M. (2020). New methodological approaches in solving certification problem of historical solid radioactive waste sent for burial from Chornobyl Nuclear Power Plant. Nuclear Power and the Environment, vol. 19, no. 4, рр. 39–49.
7. Zaffora B., Magistris M., Chevalier J., Saporta G., Luccioni C., Ulrici L. (2017). A new approach to characterize very-low-level radioactive waste produced at hadron accelerators. Appl. Radiat. Isot., vol. 122, pp. 141–147. Available at: https://hal.archives-ouvertes.fr/hal-01555113/document.
8. Kim T. H., Park J., Lee J., Kim J., Kim J. Y., Lim S. H. (2020). Statistical methodologies for scaling factor implementation: Part 1. Overview of current scaling factor method for radioactive waste characterization. Journal of Nuclear Fuel Cycle and Waste Technology, vol. 18, no. 4, pp. 517–536. doi.org/10.7733/jnfcwt.2020.18.4.517.
9. Albertone L., Altavilla M., Marga M., Porzio L., Tozzi G., Tura P. (2019). Control experiences regarding clearable materials from nuclear power plants and nuclear installations: Scaling factors determination and measurements’ acceptance criteria definition. Environments, vol. 6 (11), p. 120. doi.org/10.3390/environments6110120.
10. ISO 21238:2007. Nuclear energy — Nuclear fuel technology — Scaling factor method to determine the radioactivity of low- and intermediate-level radioactive waste packages generated at nuclear power plants. Geneva: International Organization for Standardization, 2007.
11. Taddei M. H. T., Macacini J. F., Vicente R., Marumo J. T., Terremoto L. A. A. (2015). Determination of scaling factors to estimate the radionuclide inventory of wastes from the IEA-R1 research reactor. J. Radioanal. Nucl. Chem., vol. 303, no. 3, рp. 2467–2481. doi.org/10.1007/s10967-014-3789-3.
12. Zaffora B., Magistris M., Saporta G., La Torre F. (2016). Statistical sampling applied to the radiological characterization of historical waste. EPJ Nuclear Sci. Technol., vol. 2, no. 34, pp. 1–11. doi.org/10.1051/epjn/2016031.
13. Kim T., Kang K., Ha J. (2008). Determination and verification of the scaling factor for the radionuclide inventory of the radioactive waste from nuclear power plants. Journal of Nuclear Science and Technology, vol. 45, sup. 5, pp. 756–757. doi.org/10.1080/00223131.2008.10875965.
14. Kim A. M., Lietzmann F. (2019). Nuclide vector for decommissioning and release measurements in Germany. Proceedings of the Transactions of the Korean Nuclear Society Autumn Meeting (Goyang, Korea, October 24–25, 2019). Available at: www.kns.org/files/pre_paper/42/19A-032-AndreaMaria.pdf.
15. Mykhailov O. V. (2022). [Results of radionuclide vector verification to characterize solid radwaste of Chornobyl Nuclear Power Plant sent for burial]. Nuclear Power and
the Environment, vol. 2 (24), рр. 43–53. (in Ukr.)
16. Production process control system. Methodology for the determination of radionuclide vectors for the characterization of batches of solid radioactive waste. STP 2.035–2018. Slavutych: SSE “ChNPP”, 2018, 24 p. (revised 2020).
17. Maceika E., Remeikis V., Juodis L., Gudelis A., Plukis A., Plukiene R., Duškesas G., Baltrunas D. (2009). Principles of optimal sampling for characterization of solid radioactive
waste of the Ignalina Nuclear Power Plant. Lithuanian J. Phys., vol. 49, pp. 341–350. doi.org/10.3952/lithjphys.49313.
18. Mykhailov O. V. (2021). [Results of comparative evaluation of algorithms for calculating scaling factors of difficult-to-measure nuclides in ChNPP wastes at 241Am example]. Nuclear Power and the Environment, vol. 2 (21), pp. 61–70. (in Ukr.)
19. OECD (2017). Radiological characterization from a waste and materials. End-state perspective: practices and experience (NEA-7373). Nuclear Energy Agency of the OECD
(NEA), 100 p. Available at: www.oecd-nea.org/rwm/pubs/2017/7373-rad-char-pers.pdf.
20. Ross S. M. (2004). Introduction to probability and statistics for engineers and scientists. Third Edition. USA: Elsevier Academic Press, 641 p.
21. Zaffora B., Demeyer S., Magistris M., Ronchetti E., Saporta G., Theis C. (2020). A Bayesian framework to update scaling factors for radioactive waste characterization.
Appl. Radiat. Isot., vol. 159. doi.org/10.1016/j.apradiso.2020.109092.
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.