Authors & Affiliations
Kazantsev A.A., Supotnitskaya O.V., Sergeev V.V., Astakhova N.E.
A.I. Leypunsky Institute for Physics and Power Engineering, Obninsk, Russia
Kazantsev A.A. – Leading Researcher, Cand.
Sci. (Tech.), associate professor. Contacts: 1, pl. Bondarenko, Obninsk, Kaluga region, Russia, 249033. Tel.: +7 (484) 399-51-97; e-mail:
Supotnitskaya O.V. – Head of Laboratory.
Sergeev V.V. – Senior Researcher.
Astakhova N.E. – Thermal Physics Engineer.
Abstract
The article describes the design procedure for determining the yield of radiolytic hydrogen depending on the residual heat power. The calculation method additionally takes into account the yield of hydrogen when changing the solubility of hydrogen from the water temperature, which determines the rate of nonlinear release of dissolved hydrogen into the gas volume of the pool with an increase in water temperature. The presented procedure is used to determine the rate of release of dissolved radiolytic hydrogen in order to find hydrogen sources in the fuel pool (FP) room. Processes occurring during beyond design basis accident of boiling reactor of Bilibino NPP with natural coolant circulation in fuel pool (FP) are considered. Failure of heat removal during nuclear fuel (NF) storage in FP in case of ventilation system failure and failure of power supply systems of FP room is considered as initiating event. Depending on the value of the total FA power in the FP pool, conservative and realistic versions of the accident scenario are considered. The conservative approach considers the moment when the power of residual heat is maximum, the water in the FP boils off when heated to saturation temperature or slightly lower. Taking into account the yield of dissolved hydrogen practically doubles the rate of hydrogen yield over the water heating time interval. In a realistic approach, an option with a real modern total residual heat is considered, when, with insufficient power, water is heated to a temperature significantly below boiling point and evaporates from the surface in a much longer time. The yield of hydrogen dissolved in water of FP is significantly reduced. In this work, the calculation of the dependence on the evaporation intensity from temperature level at 1 m2 of the surface is based on the international standard VDI-2089, where the evaporation rate is due to the gradient of partial pressure on the water surface and the partial pressure of steam in the gas volume.
Keywords
boiling reactor, radiolysis products, Bilibino Nuclear Power Plant (BiNPP), Heterogeneous Power Loop Reactor with 6 coolant circulation loops (EGP-6), hydrogen explosion safety, hydrogen solubility in water, beyond design basis accident (BDBA), fuel pool (FP), spent nuclear fuel (SNF), spent fuel assembly (SFA), reactor facility (RF), heat exchanger (HE), evaporation from pool mirror
Article Text (PDF, in Russian)
UDC 621.039.534:541.15
Problems of Atomic Science and Technology. Series: Nuclear and Reactor Constants, 2022, no. 4, 4:9