A Pilot Study on Applying Option 2 to Two Systems in the UCN 3, 4 - HPSI, ESWS

This report describes the Option 2 method applied to high pressure safety injection system(HPSI) and essential service water system(ESW) UCN 3,4 based on the U.S NEI 00-04 Option 2 methodology. Thus, in the Option 2 applications under the 10 CFR 50.69 requirement, the special treatment requirements for 'RISC-3' SSCs could be relaxed, while the regulartory requirements for 'RISC-2' SSCs will be enhanced. The results of Option 2 applications for the two systems of UCN 3,4 show that 161 out of 277 safety related SSCs can be treated with relaxed requirements in the HPSI, while 20 non-safety related SSCs should be treated with special treatment requirements. Also, in the ESW, special treatment requirements for the 121 out of 238 safety related SSCs can be relaxed, and new special treatments are required for 4 non-safety related SSCs