Towards Unified Protocol for Par's Performance Rating and Safety Margins Assessment: Par Life-cycle Systemic Model

Passive  Autocatalytic  Recombiners  (PAR)  is  one  of  the  important  technical  mitigation   means  for hydrogen    combustion    in    the    NPP    containments    under    accident     conditions.    For    the PWR/VVER/CANDU units the PARs execute functions important for safety - reduce the local hydrogen concentration  to  an  acceptable  level  and  provide  the   homogenization  of  gas  composition  and  of temperature  fields  in  the  containment.   Certification  and  licensing  of  PAR  technology  have  been accepted for the different NPP types and in the different countries on the case-by-case basement. But a comprehensive and generally accepted terminology and procedures for PAR characterization and its performance and safety rating are still absent. As a next step in PAR's technology improvement and maturity, it would be logical a development of their unified technical standardization and certification. Report is aimed to - 2) justify need in standardization of the PARs in the nuclear industry and in the hydrogen energy applications, 2) define a minimal set of the notions, which can be used for quantitative characterization of the of PARs throughout its life-cycle, 3) formulate a systemic (generic state-machine or automata) model of PAR's states under the normal and accident conditions. After verification and validation  of  proposed  PAR  systemic  model  it  can  be  used as  one  of  ints  for  the development of an international standard for PAR performance and safety.