Design features and prevention and mitigation measures

Design features

Additional prevention and mitigation measures

Core melt

• Active medium and low-pressure safety injection (TQn3 and TQn2);

• Passive Hydro Accumulators;

• Emergency boron injection (TQn4).

• Additional diesel generators;

• Qualification of some systems to operate as safety systems (TK system);

• Water injection in reactor core or SG by mobile fire protection equipment in extreme conditions.

Core melt under high pressure

• Primary depressurization system;

• Safety valves;

• Spray system.

• Qualification of some systems operates as safety systems (YR and TK).

Pressure vessel failure

• In-vessel retention (by in-vessel injection of water).

• By external vessel cooling with water

External steam explosion

• None. The cavity is dry.

• Need additional investigation in case of flooding of cavity for In-Vessel Melt Retention(IVMR).



• In-vessel melt retention by water injection.

• Plugging all ionization chamber channels located in the walls of the reactor vessel cavity;

• Ex-vessel measures (see below).

Containment overpressure

• Containment spray (earlier phase);

• Larger containment free volume.

• Containment venting system (scrubber).

Hydrogen detonation

• Larger containment free volume.

• Hydrogen recombiners;

• Long term containment management (risk for late phase release).

Containment bypass

• Accident management (for Primary to Secondary (PRISE) events using appropriate procedures).

• Ex-vessel measures (corium spreading, corium cooling by water supplying);

• Long term cooldown of corium.

Accident in spent fuel pool (SFP)

• Water level and temperature monitoring;

• Emergency water supply system.

• Even SFP heat distribution;

• Water injection in SFP by mobile fire protection equipment in extreme conditions.