Please join my meeting on your computer:
Seminarium Zakładu Energetyki Jądrowej i Analiz Środowiska (UZ3)
Departament Badań Układów Złożonych (DUZ)
Study on the DLOFC severe accident scenario of the GEMINI HTR reactor with MELCOR and SPECTRA code
The work presented in this seminar was performed within the Euratom Horizon 2020 GEMINI Plus project. The behaviour of the HTGR reactor under severe accident conditions was investigated and the maximum fuel temperature was observed. Due to the application of the TRISO particles and SiC layers in the fuel element, no damage to the fuel is guaranteed up to 1600°C.
Under the cooperation in the project between Nuclear Research Group (NRG) and National Centre for Nuclear Research (NCBJ) a code to code calculations was carried out between the SPECTRA and MELCOR codes. SPECTRA code, developed by the NRG is a thermal hydraulic analysis code and MELCOR 2.1.6342 used by NCBJ developed by SANDIA National Laboratory is fast running severe accident code. Both codes have already HTGR specific models build in.
The following accident was analysed: Depressurized Loss of Forced Circulation (DLOFC) with 65 mm break at the top of the reactor vessel. The scenario was calculated by applying the following sets of assumptions: best estimate and conservative. Plant behaviour was analysed including the primary and secondary side of the reactor. Code comparison has shown a good agreement of presented following characteristics on maximum fuel temperature, relative power and Reactor Cavity Cooling System power, primary pressure and break the flow.
As the results of applying conservative assumptions, it was found that fuel temperature exceeds the acceptable limit of 1600°C. Therefore changes in the core design were proposed by project participants and a new set of calculations needs to be performed.
M. Dąbrowski, T. Kwiatkowski