18.08.2015   NUCLEAR POWER PLANTS

LOCA in Zone 4

Pressure sharply decreases in DSs and RCS in the case of LOCA in Zone 4, but coolant circulation through the reactor core can be destroyed only in the latest stages of the accident, when pressure in RCS drops below 0.4 MPa. Thus, the characteristic fuel cladding and channel walls temperature peak within the first seconds of the accident (in case of LOCA in Zone 1 and Zone 2) is not met there. Guillotine breaks of one and two steamlines were considered for the large LOCA in RCS Zone 4: [3]

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Fig. 19. Comparison of accident consequences in case of breaks in Zone 1 (MCP PH break) and Zone 4 (steamlines break)