ML20236V581
| ML20236V581 | |
| Person / Time | |
|---|---|
| Issue date: | 07/31/1998 |
| From: | Wessman R NRC (Affiliation Not Assigned) |
| To: | Reedy R AFFILIATION NOT ASSIGNED |
| References | |
| GL-96-06, GL-96-6, NUDOCS 9808040060 | |
| Download: ML20236V581 (5) | |
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UNITED STATES l
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NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 30eeH001 p,
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July 31, 1998 Mr. Roger Reedy Reedy Engineering, Inc.
3425 S. Bascom Avenue, Suite 210 Campbell, California 95008
SUBJECT:
RESPONSE TO LETTER OF JUNE 11,1998, REGARDING GENERIC LETTER 96-06
Dear Mr. Reedy:
I am responding to your letter of June 11,1998, regarding U.S. Nuclear Regulatory Commission (NRC) Generic Letter (GL) 96-06, " Assurance of Equipment Operability and Conta!nment Integrity During Design-Basis Accident Conditions." You previously expressed an interest in the staff's reassessment of Generic Safety issue (GSI) 150, " Overpressure of Containment Penetrations." As an enclosure to my April 15,1998, letter, I provided you a copy of a memorandum from Lawrence C. Shao to Gus C. Lainas, documenting the results of an Office of Nuclear Regulatory Research (RES) review of the previous evaluation performed for GSI-150. Your June 11,1998, letter indicates that you have drawn several conclusions regarding GL 96-06 based on the information contained in the RES memorandum. However, there are several statements in your letter that are not consistent with the RES memorandum and previously-stated staff views.
Item 1 of your letter contains the statement: "GSI-150 and the ' thermally induced overpressurization of isolated water-filled pipe sections in containment' identified in GL 96-06 are the identical issue." In item 2 of your letter, you imply that the scope of GSI-150 is not a subset of the scope of the issue concerning thermally induced pressurization ofisolated water-filled sections of piping cddressed in GL 96-06. The RES memorandum contains the following statements: "We have concluded that the overpressurization of piping within containment penetrations addressed within the scope of GSI-150 is a subset of the third item addressed in the GL. The GL also addresses isolated piping sections that are beyond the scope of GSI-150." You may recall that the third item of the GL is entitled "Overpressurization of isolated Piping Sections." The RES reassessment did not conclude that the scope of GSI-150 is iden'ical to the scope of the issue of thermally induced overpressurization of isolated water-filled pipe sections in containment identified in GL 96-06. In fact, GSI-150 is specifically focused on overpressurization of piping between the inner and outer containment isolatian valves (i.e., the penetration area). GL 96-06 includes overpressurization of piping that tnay or may not include the containment penetration (see Maine Yankee event on page 4 of the GL).
l Consequently, we cannot agree with your items 1 and 2.
I Item 3 of your letter contains the statements: "GSI-150 addressed 'the thermally inc',uced overpressurization of isolated water-filled pipe sections in containment' and concluded this was not a safety issue and placed the issue into the ' DROP' ranking. For this and many other good ID technical reasons addressed by the ASME Code, there was never any good reason to address
' thermally induced pressurization' in GL 96-06." The RES memorandum contains the following 3
l statements:
- Based upon a review of the prioritization of GSI-150, GL 96-06, and discussions D,P
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2 conceming ASME Section Ill, RES concludes that the issue covered in the scope of GSI-150 is a compliance issue. Additionally, we conclude that this issue is adequately addressed in GL 96-06 " The RES review concluded that the issue of thermally induced pressurization was appropriately addressed as a compliance issue in GL 96-06. We agree with the RES conclusion.
Item 4 of your letter contains the statement: "GSI-150 did not address whether or not there was a Code compliance issue involved, because the conclusions were based on the fact that the resulting stresses are self-limiting thermal stresses and will not cause failure in one cycle." As we have stated previously to you in Mr. Collins' letter of October 20,1997, we do not agree that I
these stresses may be categorically considered as self-limiting and that an evaluation for each configuration and loading condition may be necessary. The GSI-150 assessment in NUREG-0933 did not contain the conclusion that the stresses due to thermally-induced pressurization are self-limiting thermal stresses and will not cause failure in one cycle, in fact, the GSI-150 assessment contained an estimate of failure probability of the penetration from a I
thermal overpressure event due to an undetected flaw. Further, the RES memorandum contains the following statement: " Issues that were not addressed include the effects of non-uniform strain concentrations and compliance with design Code requirements." Therefore, the j
GSI-150 assessment may have underestimated the probability of pipe failure due to a thermal i
overpressure event. Consequently, we cannot agree with your item 4.
Item 5 of your letter contains the statement: 'GL 96-06 incorrectly states the thermal overpressure issue is an ASME Code compliance issue because the resulting stresses will exceed Code-allowable stresses." GL 96-06 does not contain the statement that the stresses resulting from thermal pressurization wdl exceed Code-allowable stresses. GL 96-06 requests that licensees determine, "if piping systems that penetrate containment are susceptible to thermal expansion of fluid so that overpressurization of piping could occur."
Item 6 of your letter contains the statement: "The ASME Code Committee has responded that the issue is not a Code compliance issue if it can be shown that one cycle of the condition will not cause failure." The NRC staff is not aware of a statement by the ASME Code Committee asserting that the issue of thermal pressurization of isolated sections of piping is not an ASME Code compliance issue. Recently issued ASME Code interpretations NI97-008 and N197-011 indicate that an evaluation of the loading condition is necessary. We provided you our comments on these Code interpretations in Mr. Collins' October 20,1997, letter.
I believe that the items discussed in your June 11,1998, letter, do not contain any new issues, and represent a repetition of views that you expressed, and we responded to, in several correspondences on the subject. Therefore, we have concluded that further discussion of the same views you raised earlier, are counter productive to effective utilization of our limited resources.
Sincerg) i D.,%M A
I Ricnard H. Wessman, Chief i
I Mechanical Engineering Branch
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Division of Engineering Office of Nuclear Reactor Regulation
3 DISTRIBUTION:
File Center /PDR EMEBRF Glainas BSheron BWetzel GHubbard REmrit JStrosnider FCherny GHolahan ESullivan i
KWichman
- See previous concurrence
)
OFFICIAL DOCUMENT NAMd: G:\\ FAIR \\ REEDY.RS7 l
To receive a copy of this document, indicate in the box C= Copy yv/o attachment / enclosure E= Copy with attachment / enclosure N = No copy i
OFFICE EMEB:DE C
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RW b n DATE 7/27/98*
7/28/98 7 M/98 OFFICIAL RECORD COPY I
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Item 4 of your letter contains the statement: "GSI-150 did not address whether or not there was a Code compliance issue involved, because the conclusions were based on the fact that the resulting stresses are self-limiting thermal stresses and will not cause failure in orye cycle." The GSI-150 assessment in NUREG-0933 did not contain the conclusion that the stresses due to thermally-induced pressurization will not cause failure in one cycle. In fact, the,GSI-150 assessment contained an estimate of failure probability of the pipe from a therpial overpressure event. Further, the RES memorandum contains the following statement: " Issues that were not addressed include the effects of non-uniform strain concentrations and com Code requirements." Therefore, the GSI-150 assessment may have undere,pliance w stimated the probability of pipe failure due to a thermal overpressure event.
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item 5 of your letter contains the statement: "GL 96-06 incorrectly states the thermal l
overpressure issue is an ASME Code compliance issue because the 'resulting stresses will exceed Code-allowable stresses." GL 96-06 does not contain the statement that the stresses resulting from thermal pressurization will exceed Code-allowable stresses. GL 96-06 requests t
that licensees determine if piping systems that penetrate containthent are susceptible to thermal expansion of the fluid so that overpressurization of piping could $ccur.
Item 6 of your letter contains the statement: "The ASME Code Committee has responded that the issue is not a Code compliance issue if it can be shown at one cycle of the condition will not cause failure." The NRC staff is not aware of a statem t by the ASME Code Committee asserting that the issue of thermal pressurization of isolat sections of piping is not an ASME Code compliance issue. Recently issued ASME Code in rpretations NI97-008 and N197-011 indicate that an evaluation of the loading condition is ne ssary. We provided you our comments on these Code interpretations in Mr. Collin October 20,1997, letter.
Sincere y, l
Richa d H. Wessman, Chief Mec nical Engineering Branch l
Divi ion of Engineering Offi e of Nuclear Reactor Regulation
- See previous concurrence Distribution:
File Center /PDR EMEB R SCollins Glainas BSheron BWetzel FMiraglia GHubbard RZimmerman i
REmrit JStrosnider FCherny BBoger GHolahan OFFICIAL DOCUMENT NAME: G:\\ FAIR \\ REEDY.RS7
/
To recove a copy of inis document. indicane in ne bon c= copy w/o attachmanitenclosure E= copy with attachment / enclosure N a No copy OFFICE EMEB DE C
EMEB DE [
C EMEB.DE C
NAME JFair KManoly RWessman DATE 7/27/98*
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{FFICIAL RECORD COPY l
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Item 4 of your letter contains the statement: "GSI-150 did not address whether o not there was a Code compliance issue involved, because the conclusions were based on th fact that the resulting stresses are self-limiting thermal stresses and will not cause failure i one cycle." The GSI-150 assessment in NUREG-0933 did not contain the conclusion that th stresses due thermally induced pressurization will not cause failure in one cycle. In fact, the GSI-150 assessment contained an estimate of failure probability of the pipe from/ thermal overpressure event. Further, the RES memorandum contains the following statemefit: " Issues that were not addressed include the effects of non-uniform strain concentrations apd compliance with design Code requirements." Therefore, the GSI-150 assessment may ha 6 underestimated the probability of pipe failure due to a thermal overpressure event.
Item 5 of your letter contains the statement: "GL 96-06 incorre ly states the thermal overpressure issue is an ASME Code compliance issue beca se the resulting stresses will exceed Code-allowable stresses." GL 96-06 does not contaf the statement that the stres resulting from thermal pressurization will exceed Code-allo,wable stresses. GL 96-06 requests that licensees determine if piping systems that penetrate containment are susceptible to thermal expansion of the fluid so that overpressurization of pipin could occur.
l Item 6 of your letter contains the statement: "The ASN) Code Committee has responded that the issue is not a Code compliance issue if it can be phown that one cycle of the condition will not cause failure." The NRC staff is not aware of a ptatement by the ASME Code Committee asserting that the issue of thermal pressurization ofisolated sections of piping is not an ASME Code compliance issue. Recently issued ASME Code Interpretations N197-008 and NI97-011 indicate that an evaluation of the loading conditio'n is necessary. We provided you our comments on these Code interpretations in Mr' Collins' October 20,1997, letter.
Sincerely, Richard H. Wessman, Chief Mechanical Engineering Branch Division of Engineering Office of Nuclear Reactor Regulation
/
Distribution:
File Center /PDR EMEB RF SCollins GLainas BSheron BWetzel j FMiraglia GHubbard RZimmerman REmrit JStrosnider FCherny BBoger GHolahan OFFICIAL DOCUMENT NAME: G:\\ FAIR \\ REEDY.RS7 l
To recewe a copy of this document, indu: ale in the bor CsCopy w/o attachmenUenclosure E= Copy with attachment / enclosure N = No copy OFFICE EMEB DE C
EMEB.DE C
EMEB.DE C
NAME JFair KManoly RWessman
]h DATE
} $8 l $8 OFFICIAL RECORD COPY
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