ML20044B525
| ML20044B525 | |
| Person / Time | |
|---|---|
| Issue date: | 05/20/1992 |
| From: | Wichman K Office of Nuclear Reactor Regulation |
| To: | Zdarek J CZECH & SLOVAK FEDERAL REPUBLIC (CSFR) (FORMERLY |
| References | |
| NUDOCS 9206250341 | |
| Download: ML20044B525 (1) | |
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W 2 0 1992 Dr. J. Zdarek, Head Reactor Materials Research Division Nuclear Research Institute 250 6B REZ Czechoslovakia
Dear Dr. Zdarek:
I received your status report on the " Applicability of the Leak Before Break Concept" in late April. Due to my schedule this is the earliest opportunity I have had to respond to your request for comments on the report.
First, let me congratulate you for developing a technically sophisticated and comprehensive program for the application of LBB to the WWER-440/230 reactor piping. You have quite accurately interpreted the rules, procedures and guidance issued by the U.S.N.R.C. on this matter. While I believe you have a difficult task before you, it is technically viable with substantial safety and economic benefits if successful.
The status report does not contain sufficient detail to offer technical comments; however, I would make the following two observations:
LBB has never been applied to U.S. pressurized water reactor main feedwater piping. This system has been subjected to severe water hammers and depending on mode of operation, thermal stratification with resultant fatigue cracking.
I would hope that these conditions do not pertain to the feedwater piping of the WWER-440/230.
In addition, U.S.N.R.C. policy is that no reduction in ECCS capacity be credited to LBB.
This policy preserves defense-in-depth and accounts for other potential sources of loss-of-coolant accidents such as failures of valves, pumps, manways and piping that are not candidates for LBB.
Once again, let me say that the program outlined in the status report appears to be very comprehensive.
Sincerely, Original Sigr,ed cy:
K.Wichman Keith R. Wichman, Head Materials Integrity Section, EMCB cc:
A.P. Kenneke, IP DISTRIBUTION:
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