Research On Hydrogen Risk And Hydrogen Mitigation Measurement Of Containment During Severe Accidents For AP1000

During severe accident in AP1000, the chemical reaction between Zircoloy and steam generates hydrogen which could be released to the containment through the RCS.Hydrogen deflagration or detonation produces both high thermal and pressure loads on the containment, which may threaten the integrity of the containment and result in the release of large quantity of radioactive materials into the environment and the public. It is of paramount importance to control and manage hydrogen risk, in order to eliminate large scale detonation for protecting the containment integrity.Ignitors and PARs are applied to reduce the hydrogen risk.First of all, this paper develops the AP1000model of MAAP and analysis the SB-LOCA+FailADS4.The research calculated the hydrogen source, water source, containment pressure, gas temperature and some other parameters. Secondly, this paper established the modeling of AP1000by using the GASFLOW code and make a CFD analysis of theSB-LOCA+FailADS4. Research shows that, ignitors consume the majority of hydrogen in the hydrogen release stage, and the PARsr have a limited effect of hydrogen mitigationon on the period; the PCS can effectively reduce the temperature and pressure of the containment; The original AP1000igniter arrangement scheme can effectively reduce the hydrogen risk of the upper space, but1#SG compartment has a high hydrogen risk;By adding two igniters in the1#SG compartment and one igniter on top of the1#SG compartment, the performance of the hydrogen mitigation system was significantly enhanced and the hydrogen risk of1#SG compartment was controled.Finally, based on the SB-LOCA+FailADS4, this paper analyzes the effect of injection time and injection rate on the post-inerting of the AP1000. The research shows that the early inert will lead to greater hydrogen risk.lt is better to start the injection at500s and choose the gas injection flow rate by23kg/s.