Izvestia Vysshikh Uchebnykh Zawedeniy. Yadernaya Energetika

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

About chemical form and binding energy of 14c in irradiated graphite of uranium graphite nuclear reactors

11/28/2017 2017 - #04 Nuclear materials

Bespala E.V. Pavliuk A.O. Zagumennov V.S. Kotlyarevskiy S.G.

DOI: https://doi.org/10.26583/npe.2017.4.11

UDC: 621.039.7

Problems related to the management of irradiated graphite of uranium graphite nuclear reactors were considered. It is shown that the choice of approaches, methods and means for handling irradiated graphite is determined by the form of the finding and binding energy of the long lived radionuclide 14C. The purpose of this work is to determine the possible chemical compounds in which 14C can be found and to assess the strength of its fixation in the structure of irradiated graphite. The domestic and foreign experience in handling graphite radioactive waste was analyzed, calculations and experiments were performed to achieve the goal. Information on the accumulation channels of 14C in the structure of reactor graphite was given and it was shown that the greatest amount of this radionuclide is formed by the nuclear reaction 14N(n, p)14C. At the same time, the majority of radioactive carbon is created on N2, which placed in unirradiated graphite in chemical impurity and in supported gas. Radionuclide 14C generated by nuclear reaction 14N(n, p)14C is localized in surface layer of graphite (including surface of pores) at a depth no more than 50 nm. Assessment of possible chemical compounds in which radioactive carbon can be located was carried out. It is proved that the form of finding is determined by the operational features of a particular graphite element in the reactor. The binding energy of 14C in the structure of irradiated graphite and the calculated depth of its penetration into the structure were estimated. Selective removal of this radionuclide is possible only at elevated temperatures in a weakly oxidative environment, which is due to binding energy up to 800 kJ / mol was established. Radiocarbon, which generated by nuclear reaction 13C(n, γ)14C is placed uniformly in irradiated graphite elements and have binding energy about 477 kJ / mol. The selective removal is possible only during crystal fracture and organization of isotope separation process. The data obtained make it possible to select methods of handling irradiated graphite during decommissioning of uranium graphite reactors.

References

  1. Rublevskij V.P., Yatsemko V.N., Chanyshev E.G. Rol’ ugleroda-14 v tehnogennom obluchenii cheloveka [The role of carbon-14 in technogeneous irradiation of people]. Moscow. IzdAT Publ., 2004. 197 p. (in Russian).
  2. Kasheev V.A., Ustinov O.A., Yakunin S.A., Zagumennov V.S., Pavliuk A.O., Kotlyarevskij S.G., Bespala E.V. Tehnologiya i ustanovka dlya szhiganiya obluchennogo reaktornogo grafita [Technology and installation for burning of irradiated reactor graphite]. Atomnaya energiya. 2013, v. 122, no. 4, pp. 210-213 (in Russian).
  3. Bushuev A.V., Kozhnin A.F., Petrova E.V., Zubarev V.N., Aleeva T.B., Girke N.A. Radioactivnyj reaktornyj grafit [The radioactive reactor graphite]. Moscow. NRNU «MEPhI» Publ., 2015. 148 p. (in Russian).
  4. Dunzik-Gougar M.L., Smith T.E. Removal of carbon-14 from irradiated graphite. Journal of Nuclear Materials. 2014, v. 451, pp. 328-335.
  5. Virgil’ev Yu.S., Seleznev A.N., Kalyagin K.A. Reaktornyj grafit: razrabotka, proizvodstvo i svojstva [The reactor graphite: development, production and properties]. Rossijskij himicheskij zhurnal. 2006, no. 1, pp. 4-12 (in Russian).
  6. Sklyar M.G. Fiziko-himicheskie osnovy spekaniya uglej [Physical and chemical foundation of agglomeration]. Moscow. Metallurgiya Publ. 1984. 201 p. (in Russian).
  7. Frolov V.V., Kryuchkov A.V., Kuznetsov Yu.N., Moskin V.A., Pankrat’ev Yu.V., Romenkov A.A. Possibility of burning irradiated graphite from decommissioned nuclear power-generating units. Atomic Energy. 2004, v. 97, no. 5, pp. 781-784.
  8. Trevethan T., Dyulegerova P., Latham C.D., Heggie M.I. Extended interplanar linking in graphite formed from vacancy aggregates. Physical Review Letters. 2013, v. 111, pp. 1-5.
  9. Pageot J., Rouzaud J.-N., Gosmain L., Deldicque D., Comte J., Ammar M.R. Nanostructural characterizations of graphite waste from French gas-cooled nuclear reactors and links with 14C inventory. Carbon. 2016, v. 105, pp. 77-89.
  10. Nefedov V.D., Skorobogatov G.A., Shvetsova V.P. Himicheskie izmeneniya, indutsiruemye reaktsiej (n, p) [Chemical modification due to induce by reaction (n, p)]. Moscow. Atomizdat Publ. 1960. 347 p. (in Russian).
  11. Vulpius D., Baginski K., Kraus B., Thomauske B. Thermal treatment of neutron-irradiated nuclear graphite. Nuclear Engineering and Design. 2013, v. 265, pp. 294-309.
  12. LaBrier D., Dunzik-Gougar M.L. Identification and location of 14C-bearing species in thermally treated neutron irradiated graphites NBG-18 and NBG-25: Pre- and Post-thermal treatment. Journal of Nuclear Materials. 2015, v. 460, pp. 174–183.
  13. Barbin N.M., Shavaleev M.R., Terent’ev D.I., Alekseev S.G. Komp’yuternoe modelirovanie termodinamicheskih protsessov s uchastiem aktinoidov pri nagreve radioaktivnogo grafita v atmosphere azota [Computer modeling of processes with actinides in radioactive graphite at heating in a nitrogen atmosphere]. Prikladnaya fizika. 2015, no. 42, pp. 42-47 (in Russian).
  14. Zhou S.Y., Gweon G.-H., Lanzara A. Low energy excitation in graphite: The role of dimensionality and lattice defects. Annals of Physics. 2006, v. 321, pp. 1730-1746.
  15. Golkarian A.R., Jabbarzadeh M. The density effect of Van der Waals forces on the elastic modules in graphite layers. Computational Materials Science. 2013, v. 74, pp. 138-142.
  16. Zeldovich Ya.B. K teorii reaktsii na poristom ili poroshkoobraznom material [About theory of reaction on porous or powdery material]. Zhurnal fizicheskoj himii. 1939, v. 13, iss. 2, pp. 163-168 (in Russian).
  17. Anischik V.M., Uglov V.V. Modifikatsiya instrumentalnyh materialov ionnymi i plazmennymi puchkami [The modification of instrumental materials by ion and plasma beams]. Minsk. Belorusskij gosudarstvennij universitet Publ. 2003. 191 p. (in Russian).
  18. Pavliuk A.O., Kotlyarevskiy S.G., Bespala E.V., Volkova A.G., Zaharova E.V. Analiz vozmozhnosti snizheniya potentsialnoj opasnosti grafitovykh radioaktivnih onhodov pri temicheskoj obrabotke [Analysis of facility of potential hazard reduction of radioactive waste under thermal treatment]. Izvestiya TPU. Inzhiniring georesursov. 2017, v. 328, no. 8, pp. 24-32 (in Russian).
  19. Kashcheev V.A., Ustinov O.A., Yakunin S.A., Zagumennov V.S., Pavlyuk A.O., Kotlyarevskiy S.G., Bespala E.V. Technology and facility for incinerating irradiated reactor graphite. Atomic Energy. 2017, v. 122, no. 4, pp. 252-256.
  20. Bespala E., Novoselov I., Ushakov I. Heat transfer during evaporation of cesium from graphite surface in an argon environment. MATEC Web of Conferences. 2016, v. 72, pp. 1-5. DOI: 10.1051/matecconf/20167201011.

uranium graphite reactor irradiated graphite binding energy strength of fixation radionuclide radiocarbon treatment decontamination