Izvestiya vuzov. Yadernaya Energetika

The peer-reviewed scientific and technology journal. ISSN: 0204-3327

The results of the transmutation of fission fragments in the spectrum of neutrons of thermal and fast reactors

6/21/2017 2017 - #02 Fuel cycle and nuclear waste management

Ivanov N.V. Kazansky Yu.A. Karpovich G.V.

DOI: https://doi.org/10.26583/npe.2017.2.11

UDC: 621.039.54(04)

The radioactivity of discharged spent nuclear fuel (SNF) from the reactor during the first hundred years is determined by fission fragments (FF), subsequently actinides contribute the main to the activity of SNF. Actual scenarios for SNF management are based on the transmutation of minor actinides (MA) into fission fragments in fast reactors. The scenarios of transmutation of fission fragments in a thermal neutron spectrum and fast neutron spectrum and the radiation characteristics as a function of time are considered. The nuclide composition of the fission fragments is based on results of modeling the burnup of the assembly 439GT (TVSA type) for VVER-1000 over three years on the MCU-5 complex. The data obtained was used to determine the initial composition of nuclides at different exposures before the initiation of transmutation (irradiation in neutron fluxes) for the ORIGEN2 program.

Three possible ways of irradiation of fission fragments are given: transmutation without cooling, cooling of fission fragments for four years before irradiation, cooling for 30 years before irradiation. The duration of irradiation was chosen equal to 3 and 15 years. Transmutation efficiency is determined by a time-dependent «coefficient of transmutation» equal to the ratio of radioactivity of nuclides in the process of transmutation and after its termination to their radioactivity without transmutation. The coefficients of transmutation were noticeable only during irradiation in the reactor: their values reached 5 – 10 and depended on the duration of the fission fragments cooling before the beginning of transmutation. After the extraction of fission fragments from the neutron flux, the coefficient of transmutation was reduced to one within several years. A hundred years after irradiation in the thermal neutron spectrum, the coefficient of transmutation is reduced to 0.8 – 0.5, depending on the duration of the transmutation process. After irradiation in the fast neutron spectrum in the interval 200 – 1000 years, a slight increase in the transmutation coefficient to values 1.2 – 1.8 is observed and then after a thousand years decrease to values of 0.9 – 0.7.

The main conclusion is a special burning of fission fragments does not make sense, because non-significant gain in radioactivity (a little less than double) comes after the thousand years.

The indifference of fission fragments to transmutation can be explained by the fraction of stable nuclides, which increases with the duration of storage of fission fragments. After the end of the cycle of fuel use, there are approximately 15% of stable nuclides among the fission fragments, and after thirty years of aging, the amount of stable isotopes reaches 85%.

References

  1. Mukaiyama T., Gurji Y. Characteristics of minor actininides transmutation in minor actinide burner reactors and power reactor. First OECD/NEA Information Exchange Meeting on Actinide and Fission Product Portioning and Transmutation. Mito City (Japan); Nov 6 – 8, 1990; pp. 326-346.
  2. Salvatores M. The physics of transmutation for radioactive waste minimisation. The Frederic Joliot summer school in reactor physics. Cadarache, France, August 1998.
  3. Kazansky Yu.A, Dudkin A.I., Klinov D.A. Transmutacija: moda ili neobhodimost’? [Transmutation: fashion or necessity?] Izvestiya vuzov. Yadernaya Energetika. 1993, no. 1, pp. 65-69 (in Russian).
  4. Gay E.V., Ignatyuk A.V., Rabotnov N.S., Shubin Yu.N.. Koncepciya obrashcheniya s dolgozhivushchimi yadernymi othodami [Concept treatment of long-lived nuclear waste management]. Izvestiya vuzov. Yadernaya Energetika. 1994, no. 1, pp. 17-21 (in Russian).
  5. Shmelev A.N., Apse V.A., Kulikov G.G., Morin D.V., Novikov A.E. O transmutacii dolgozhivushhih produktov deleniya v yadernyh ustanovkakh [On the transmutation of long-lived fission products in nuclear facilities]. Izvestiya vuzov. Yadernaya Energetika. 1994, no. 1, pp. 30-37 (in Russian).
  6. Slessarev I., Salvatores M. The potential of nuclear transmutation: «neutron economics» of critical reactors and hybrids. Proc. of the International Conference on Evaluation of Emerging Nuclear Fuel Cycle Systems. Versailles (France); Sep 11 – 14 1995, v. 1, pp. 482-488.
  7. Krivitski I.Yu. Actinide and Fission Produuct Burning in Fast Reactors with a Moderator. Proc. of the Int. Conf. On Future Nucl. Syst. GLOBAL-99. USA, Jackson Hole, Wyoming. Aug 29 – Sep 3 1999.
  8. Kazansky Yu.A, Klinov D.A. Effektivnost’ transmutacii oskolkov deleyniya [Transmutation Efficiency of Fission Fragments.] Izvestiya vuzov. Yadernaya Energetika. 2000, no. 4, pp. 38-46 (in Russian).
  9. Yang W. S., Kim Y., Hill R. N., Taiwo T. A. and Khalil H. S. Long-Lived Fission Product Transmutation Studies. Nuclear Science and Engineering. 2004, v. 146, pp. 291-318.
  10. Kun Liu, Hongchun Wu, Liangzhi Cao, Youqi Zheng. Studies on LLFP transmutation in a pressurized water reactor. Journal of Nuclear Science and Technology. 2013, v. 50, no. 6, pp. 581-598.
  11. Gurevich M.I., Shkarovsky D.A. Raschet perenosa nejtronov metodom Monte%Karlo po programme MCU [Calculation of neutron transport by the Monte Carlo method according to the program of the MCU]. Мoscow. NRNU MEPhI Publ., 2012. 154 p. (in Russian).
  12. Lotsch T., Khalimonchuk V., Kurchin A. Proposal of a benchmark for core burnup calculations of a VVER-1000 reactor core. AER Symposium on VVER Reactor Physics and Reactor Safety; Varna (Bulgaria); Oct 21 – 25 2009; p. 57.
  13. Croff A.G. A User’s Manual for the ORIGEN2 Computer Code. Oak Ridge National Lab., TN (USA). July, 1980; 196 p. Available at: https://inis.iaea.org/search/search.aspx?orig_q=RN:11560149 (accessed 02.02. 2017).

fission products transmutation transmutation coefficient radioactivity

Link for citing the article: Ivanov N.V., Kazansky Yu.A., Karpovich G.V. The results of the transmutation of fission fragments in the spectrum of neutrons of thermal and fast reactors. Izvestiya vuzov. Yadernaya Energetika. 2017, no. 2, pp. 118-125; DOI: https://doi.org/10.26583/npe.2017.2.11 (in Russian).

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