Analysis of severe accidents progression specifics at NPP power units with VVER-1000 from a perspective of fission products release

Analysis of severe accidents progression specifics at NPP power units with VVER-1000 from a perspective of fission products release.

Kurbonmamadov A. Sh., Arbaev G. E.

In the article the analysis of various severe accidents progression scenarios using the example of the NPP power unit with VVER-1000 was performed from a perspective of fission products release and distribution by NPP premises. Also, the influence of possible equipment failures on the accident processes development is considered.
For the purpose of the current research several severe accident scenarios were calculated to consider leaks from hot and cold legs of the main circulation pipeline of various diameters overlapped by total loss of all alternative current sources.
As a result the following aspects were revealed:
1. difference in processes development from a perspective of fission products release under loss-of-primary coolant accidents depending on the location of the leak (cold or hot leg of the main circulation pipeline);
2. possibility of reactor vessel failure (destruction) due to its considerable heating under high pressure in the reactor installation in case of accidents involving long-term loss of power supply;
3. possibility of formation of conditions for steam explosion in the reactor lower plenum during core melt-water interaction.
The obtained results require an additional analysis and should be considered in severe accidents calculations for NPP power units with VVER-1000, which will favorably affect the quality of severe accidents calculated simulation for NPP power units with VVER.

Keywords: severe accidents, fission products, steam explosion, VVER.

Article language: Russian. Pp. 51–60. [in Russian]. DOI: 10.26277/SECNRS.2023.107.1.005.