Izvestiya vuzov. Yadernaya Energetika

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

Use of erbium as a burnable absorber for the VVER reactor core life extension

9/16/2020 2020 - #03 Nuclear power plants

Alassaf S.H. Savander V.I. Hassan A.A.

DOI: https://doi.org/10.26583/npe.2020.3.06

UDC: 621.039

The paper presents the results of a computational and theoretical analysis dealing with the use of erbium as a burnable absorber in VVER-type reactors. Partial refueling options for the reactor life extension (to a year and a half to two years) are considered, the refueling ratio being equal to three for the former and to two for the latter. Erbium is expected to be present in all fuel elements in the FA with the same weight content.

The influence of the erbium weight content on such reactor and fuel neutronic characteristics as burn-up, reactivity coefficients, residual volume of «liquid control», and volumes of the liquid radioactive waste formed has been estimated. Calculations were performed based on a simplified refueling model without FA reshuffling. An infinite mesh of polycells, consisting of FAs with different in-core times, was considered. The neutron escape from the core was taken into account through the selection of the critical value KҐ at the end of life.

Erbium does not burn up altogether for the core life which affects the fuel burn-up reduction as compared with the liquid system for excessive reactivity compensation. The reduction is 0.7% per 0.1% of the erbium weight load in the fuel element. This, however, also reduces the maximum content of the boron absorber in the coolant and the accumulation of LRW in the ratio of 5% per 0.1% of the erbium weight load.

Erbium influences the spectral component of the coolant temperature reactivity coefficient which turns out to be negative even with a minor weight fraction in fuel and the decrease in the boron absorber fraction leads to a positive value of the density reactivity coefficient. As the result, the total coolant temperature reactivity coefficient has a negative value throughout the life.

References

  1. U.S. Department of Energy. DOE Fundamentals Handbook: Nuclear Physics and Reactor Theory, Vol. 2. Washington USA. 1993. 128p.
  2. Frybort J. Erbium burnable absorber for high-burn up fuels, WoS 000321966500252. Proc. of the XIII-th International Scientific Conference EPE 2012. Czech Republic, 2012, pp. 1299-1304.
  3. Fedosov A.M. RBMK Uranium-Erbium Fuel. Atomic Energy, 2018, v.v124, no. 4, pp. 221-226.
  4. Franceschini Fausto, Petrovich Bojan. Fuel with Advanced Burnable Absorbers Design for the IRIS Reactor Core: Combined Erbia and IFBA. Annals of Nuclear Energy. 2009, v. 36, iss. 8, pp. 1201-1207; DOI: https://doi.org/10.1016/j.anucene.2009.04.005 .
  5. Franceschini Fausto. Use of Isotopically Modified Erbium to Improve Fuel Cycle Economics in IRIS. Proc. of the V-th International Conference on Nuclear Option in Countries with Small and Medium Electricity Grids, INAC, 2017, pp. 1-12.
  6. Semchenkov Yu. Using Fuel in VVER Reactors: Condition and Prospects. Rosenergoatom, 2014, no. 11, pp. 8-13 (in Russian).
  7. Savander V.I., Al’assaf S.H. Analysis of the Effectiveness of Using Extended Core Life Cycle in VVER Reactor in the Foreign Countries. Yadernaya Fizika i Inzhiniring. 2019, v. 9, no. 4, pp. 1-4 (in Russian).
  8. Pryanichnikov A.V. Description of the GETERA Code. VANT. Ser. Fizika yadernyh reaktorov. 2009, no. 3, pp. 63-76 (in Russian).
  9. Bergelson B.R., Belonog V.V., Gerasimov A.S., Tikhomirov G.V. VVER Nuclear Fuel Burnup with Different Absorbers. Atomic Energy. 2011, v. 109, no. 4, pp. 240-245; DOI: https://doi.org/10.1007/s10512-011-9351-2 .
  10. Abu Sondos M.A., Demin V.M., Savander V.I. Decrease the Volume of Boric Regulation of the Reactivity when Using the Burnable Absorber on the Basis of GD2 O3 in the Fuel Reactor WWER-1200. Global’naya Yadernaya Bezopasnost’. 2019, no. 3 (32), pp. 56-65; DOI: https://doi.org/10.26583/gns-2019-03-06 (in Russian).
  11. HashlamunT.M., VygovskiyS.B., LeskinS.T., DumanA.S. Determination of 18-month Fuel Cycle Parameters with Goal of Fuel Costs Minimization at the Basis of Use Constructions of Fuel Assemblies in VVER-1200 Reactors. Izvestiya vuzov. Yadernaya Energetika. 2018, no. 3, pp. 113-124; DOI: https://doi.org/10.26583/npe.2018.3.10 (in Russian).

VVER burnable absorber erbium reactivity margin GETERA liquid excessive reactivity compensation system liquid radioactive waste (LRW)