Proposed 10CFR 50.46c and early ACRS Observations

Of course, proposed revisions to 10 CFR 50.46 has been an ongoing activity. for decades.  Here are a few paragraphs that I wrote a while back (2002).

4.3  Runaway Discussions at the Advisory Committee for Reactor Safeguards (ACRS)

The USNRC is currently working on revisions to rule 10 CFR 50.46 concerning emergency core cooling systems for reactors.  The process is called  risk-informing the regulation.  The ACRS discussions of Friday, May 31, 2002, are revealing in that several aspects of the revisions were discussed, however, the ubiquitous fouling of today’s LWRs was not considered.  This was a combined meeting of three of the most influential subcommittees of the ACRS: Materials and Metallurgy; Thermal Hydraulic Phenomena & Reliability and Probabilistic Risk Assessment

         

Member Graham B. Wallis was especially enraged by the limited approaches to fuel integrity under LOCA conditions.  In response to detailed descriptions of fracture of corroded specimens of cladding from irradiated power reactor fuel he asserted:  “It seems to be that both these coursing tests and hitting tests, impact tests and the squeezing tests are not really typical of the loads imposed on the real cladding.. I keep wondering what the relevance of all these tests are to the real truth.”  He also reacted to the discussions of  runaway,  “I think when you come back and talk about run-away to this committee you better have a criterion for run-away and not this sort of vagueness about heat transfer.”