Comparison of the Effect of Burnable Absorbers (Gd and Eu) on the Neutron-Physical Characteristics of VVER-1000 Fuel Assemblies

 The problem of using burnable absorbers in VVER reactors to reduce the volume of liquid regulation of excess fuel burnup reactivity has been considered. The use of burnable absorbers such as Gd₂O₃ and Eu₂O₃ in nuclear fuel has a positive effect on the nuclear fuel cycle of light-water reactors PWR (VVER-1000) and BWR (RBMK) and leads to an increase in the duration of the campaign and some other positive properties. However, the presence of burnable absorbers in fuel simultaneously deteriorates the uniformity of the energy field and a number of other negative properties. Previous studies of the possibility of reducing these negative results have been presented. One of the proposed technical solutions is to change the structure of gadolinium placement in fuel rods. In this work, the influence of the placement of burnable absorbers (Gd₂O₃ and Eu₂O₃) on the neutron-physical characteristics of nuclear fuel of VVER-1000 reactors has been studied. These characteristics are the infinite neutron multiplication factor, the coefficient of uneven distribution of energy release, and the accumulation of isotopes depending on the burnup.

1. Jaehong Lee, Jun-ichi Hori, Ken Nakajima, Tadafumi Sano & Samyol Lee. Neutron capture cross section measurements of 151, 153 Eu using a pair of C6D6 detectors. P. 1046–1057 | URL: https://www.tandfonline.com/doi/full/10.1080/00223131.2017.1344575 Received 14 Oct 2016, Accepted 23 May 2017, Published online: 17 Jul 2017.

2. Burnable Absorbers – Burnable Poisons. URL: https://www.nuclear-power.com/nuclear-power-plant/nuclear-fuel/burnable-absorbers-burnable-poisons. (Accessed 21. 01. 2018).

3. Stogov Yu. V., Belousov N. I. Savander V. I. et al. Perspektivnye tekhnologii ispol`zovaniya oksidnogo uran-gadolinievogo topliva v legkovodnykh reaktorax [Promising Technologies for the Use of Uranium-Gadolinium Oxide Fuel in Light-Water Reactors]. Materialy` XIV seminara po problemam fiziki reaktorov [Proceedings of the XIV Seminar on Reactor Physics]. Moscow: MEPhI. 2006. P. 45–47 (in Russian).

4. Balestieri D. Issledovanie UO₂/Gd2O3 toplivnoj smesi. IAEA-TECDOC-1036. Vienna (Austria). 1998. P. 63–72.

5. Ermolin V. S., Okunev V. S. O razmeshchenii gadoliniya v central`nom otverstii tvelov vodo-vodyany`kh reaktorov [Placement of Gadolinium in the Central Opening of Water–Water Reactor Fuel Rods]. Fiziko-tekhnicheskie problemy yadernoj energeti [Physical and Technical Problems of Nuclear Power Engineering]. Nauchnaya sessiya MIFI [Scientific Session of ME-PhI]. 2008. P. 101–102 (in Russian).

6. Bergelson B., Belonog V., Gerasimov A. et al. Glubina vygoraniya yadernogo topliva VVER s raznymi poglotitelyami [Depth of Burn-Up of WWER Nuclear Fuel with Different Absorbers]. Atomnaya energiya [Atomic Energy]. V. 109. Vol. 4. October 2010. P. 240–245 (in Russian).

7. Abdelghafar Galahom A. Issledovanie vozmozhnosti ispol`zovaniya splava evropiya i Pireksa v kachestve szhigaemogo poglotitelya v PWR [Study of Possibility of Europium and Pyrex Alloy Using as Burnable Absorber in PWR]. Annaly yadernoj energii [Annals of Nuclear Energy]. V. 110. December 2017. P. 1127–1133 (in Russian).

8. Leppänen J. SERPENT – a Continuous-energy Monte Carlo Reactor Physics Burnup Calculation Code. VTT Technical Research Centre of Finland. (June 18, 2015).

9. Ondrej Novak, Ondrej Chvala, Nicholas P. et al. “VVER 1000 Khmelnitskiy benchmark analysis calculated by Serpent2”. Annals of Nuclear Energy 110 (2017). P. 948–957.

10. Nuclear fuel for VVER reactors. URL: http://www.tvel.ru/was/otklucheny/podklyuchenie/tel/tvel-site/resursov/9a8c448042df8fd7a492b7b2cb3f9f43/Nucle-arFuel_RUS_2017.pdf. (Accessed 21. 01. 2018).

11. Chadwick M. B., et al. ENDF/B-VII.1 nuclear data for science and technology: cross sections, covariances, fission product yields and decay data. Nucl. Data Sheets, 112 (2011). Р. 2887–2996 doi: 10.1016/j.nds.2011.11.002.