A Pilot Study on Applying Risk Informed Application Option 2 to Two Systems in UCN 3

To reduce the unnecessary burden of a regulation, NRC prepared three options for the risk informed regulatory framework known as Option 1, Option 2 and Option 3. In Option 2, all safety related Structure, System and Components (SSCs) and non-safety related SSCs are evaluated from a safety point of view, and the low safety significant SSCs belonging to the safety related group are called 'Risk Informed Safety Class (RISC) - 3' SSCs. The 'RISC-3' SSCs can be exempted from the special treatment requirements such as a seismic and environmental requirement, of 10 CFR 50. For Option 2, 10 CFR 50.69 was issued by US NRC, and NEI 00-04 was prepared by US industry as a categorization guideline for 10 CFR 50.69, and US NRC endorsed the NEI 00-04 methodology for Option 2 in Reg. Guide 1.201. This paper describes the Option 2 method applied to the high pressure safety injection system (HPSI) and the essential service water system (ESW) of UCN 3