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Verification of GOTHIC Multivolume Containment Model during NPP Krško DBA LOCA

Tomislav Fancev ; University of Zagreb, Faculty of Electrical Engineering and Computing Unska 3, 10000 Zagreb, Croatia
Davor Grgić ; University of Zagreb, Faculty of Electrical Engineering and Computing Unska 3, 10000 Zagreb, Croatia
Siniša Šadek ; University of Zagreb, Faculty of Electrical Engineering and Computing Unska 3, 10000 Zagreb, Croatia

Sažetak

New containment multivolume model of NPP Krsko for GOTHIC code is developed. It is
based on plant drawings and other available data. It is supported by developed SketchUp 3D
containment model. The model is subdivided in volumes following physical boundaries and clearly
defined flow paths. All important concrete heat structures are taken into account. Metal heat
structures are based on plant’s SAR Chapter 6 licensing model. RCFC (Reactor Containment Fan
Cooler) units are explicitly modelled as well as all main ventilation ducts. The model includes two
trains of containment spray system. PARs (Passive Autocatalytic Recombiner) and PCFV (Passive
Containment Filter Venting) filters added during plant safety upgrade project are part of the model
too.
It was intention to use model for both DBA (Design Basis Accident) and for DEC (Design
Extended Conditions) and BDBA (Beyond Design Basis Accident) calculations. Based on the same
discretization and data, and on experience acquired during GOTHIC model development and use,
containment models for MELCOR and MAAP integral codes are developed too.
As part of initial verification of the GOTHIC model containment DBA LOCA calculation is
performed using SAR MER (Mass and Energy Release) data. The influence of different break
positions on peak containment atmosphere pressure and temperature was studied. The results were
compared against results obtained in single volume containment licensing model. Beside local
effects due to different containment subdivision similar results are obtained when comparing
containment dome from multivolume and the single volume in licensing model. Special attention
was paid to distribution of water in lower part of the containment during recirculation phase. In this
case much more valuable information are obtained in multivolume model with explicit volumes for
main sump, recirculation sump and sump pit. Another point of interest was influence of
containment spray duration on long term pressure and temperature behaviour. The intention was to
study consistency of assumed different spray operation times used in safety analyses, EQ analyses
and SAMGs and related consequences for plant operation during DBA LOCA.

Ključne riječi

containment; LOCA; GOTHIC; multivolume model; spray operation time

Hrčak ID:

199647

URI

https://hrcak.srce.hr/199647

Datum izdavanja:

1.9.2017.

Posjeta: 578 *