[en] OECD/CSNI organized a special task force group to evaluate current technology for estimating LWR source term. One of the tasks of the task force group was to review and evaluate roles of engineered safety features (ESFs) of LWR in severe accidents. Among ESFs, containment sprays, icecondensers, filter system including SGTS and fan cooler were discussed by JAERI. In addition to the ESFs, the filtered-vented containment was also included in the discussion. The following comments were made through the discussions. 1) ESFs are in general effective to reduce fission products. 2) ESFs will be important when operator action is considered. 3) In that case, vulnerability of ESFs components must be evaluated. 4) A filtered-vented containment seems effective in reducing fission products. (author)