Two of the six respondents who responded to this question only provided frequencies out to Category 5 LOCAs even though BWR non-piping could cause a Category 6 (Vessels) LOCA; thus Rob only provides results for Category 5 LOCAs here.

Concern with thermal aging of cast stainless steel is when it is present in concert with some other degradation mechanism.

CRDM refers to stud tube housing on bottom head of BWRs.

Panelist F didn’t consider RPV for Category 1 LOCAs; question was whether they didn’t think important or did they not have a means of making an evaluation.

There is much less spread in results for RPV than valves and pumps; panelists spent more time and more work in past on RPV than pumps and valves.

Panelist C sees a decrease in freq with time but may be an artifact of the fact that he anchored against BWR recirculation line that shows a decrease in LOCA frequency with time; he provides no rationale for why he would expect non-piping LOCA frequency to decrease with time.