Blackout Accident Management Strategies at Nuclear Power Plants

V. І. Skalozubov, V. Yu. Grib, A. V. Korolev, T. V. Gablaya, V. Yu. Kochneva

Odessa National Polytechnic University,
1, Shevchenko av., Odesa, 65044, Ukraine

DOI: doi.org/10.31717/2311-8253.19.2.2

Abstract

Technical shortcomings of nuclear power plants (NPP) with boiling water reactors and the inadequate training of operating staff for blackout accident management are among the main causes of severe accidents and destructive explosions at the Fukushima-Daiichi NPP. The blackout at Fukushima-Daiichi NPP was a consequence of the site flooding because of combined effect of the earthquake (about 9 points in the epicenter at a distance of 160–180 km from coast) and tsunami with a height of more than 14 m near the coast. The Fukushima-Daiichi site is placed at a height of 10 m above sea level, and there is a system of breakwaters with a height of more than 4 m above sea level. According to design calculations, the maximum wave height off the coast is about 5 m. Therefore, the accident was great surprise for the operating organization Tokyo Electric Power Company, and it revealed unpreparedness of technical means and staff in preventing consequences of the initial accident event. After Fukushima-Daiichi accident double inspections were hold at all US nuclear power plants. They also demonstrated insuffi-cient preparedness of technical means and staff for blackout accident management. Analysis of current and developed guidelines/instructions for the severe accident management at reactor facilities has revealed that the accepted blackout accident management strategies at NPP with water-water energetic reactor (VVER) are not substantiated and not effective enough. A comprehensive blackout accident management strategy is described in the paper. The strategy is based on an integrated approach to ensuring the safety functions of afterheat removal from the reactor and maintaining the required level of boiler water in the steam generator. The strategy is realised by alternative emergency steam-driven feed pumps at steam generator pressure of more than 0.3 MPa, and by afterheat removal passive systems based on the principles of natural circulation at lower pressures.
Practical implementation of the proposed blackout accident management strategy determines the need of additional experimental design qualification of new passive safety systems

Keywords: accident management, blackout, nuclear power plant.

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