ML030920682
| ML030920682 | |
| Person / Time | |
|---|---|
| Site: | Nine Mile Point  |
| Issue date: | 03/25/2003 |
| From: | Stephanie Coffin NRC/NRR/DE/EMCB |
| To: | Terry C Constellation Generation Group |
| References | |
| Download: ML030920682 (6) | |
Text
March 25, 2003 Carl Terry, BWRVIP Chairman Constellation Generation Group Nine Mile Point Nuclear Station Post Office Box 63 Lycoming, NY 13093
SUBJECT:
NON-DESTRUCTIVE EXAMINATION FLAW SIZING UNCERTAINTY
Dear Mr. Terry:
References:
1.
Letter from Carl Terry (BWRVIP Chairman) to NRC Document Control Desk, Project 704 - BWR Vessel and Internals Project, Shroud Vertical Weld Inspection and Evaluation Guidelines (BWRVIP-63), EPRI Report TR-1131170, June 1999, dated July 1, 1999.
2.
Letter from Carl Terry (BWRVIP Chairman) to NRC Document Control Desk, PROJECT NO. 704 -- BWRVIP Partial Response to the NRC Final Safety Evaluation of BWRVIP-63, dated October 22, 2002.
In the context of topical report BWR Vessel and Internals Project, Shroud Vertical Weld Inspection and Evaluation Guidelines (BWRVIP-63) [Reference 1], a question has been raised by the NRC staff regarding the treatment of non-destructive examination (NDE) flaw sizing uncertainty in the flaw evaluation procedures proposed by the BWRVIP. Although this question was raised with regard to BWRVIP-63, it is our understanding that it also applies to other inspection and evaluation (I&E) topical reports which the BWRVIP intends to submit for other components covered by the BWRVIP programs.
The staff understands the BWRVIP position on the treatment of NDE flaw sizing uncertainty
[Reference 2] and its potential impact on structural factors established within the BWRVIP flaw evaluation guidelines to be as follows. When a flaw is sized using a specific inspection technique/procedure (which could be either volumetric (ultrasonic examination) or surface (visual)), the licensee establishes what uncertainty in flaw dimension(s) (i.e., length and depth if a volumetric examination is being used, length only if a surface examination is being used) is associated with the inspection technique/procedure. Provided that the NDE flaw sizing uncertainty associated with the inspection technique/procedure is less than the limits specified in Reference 2, the NDE flaw sizing uncertainty does not have to be explicitly accounted for in the flaw evaluation. The assumption upon which this conclusion is based is that NDE flaw sizing uncertainty up to the specified maximum value would not significantly impact the structural factors required in the flaw evaluation procedure. If the NDE flaw sizing uncertainty associated with the specific inspection technique/procedure which the licensee is using is not less than the specified maximum value, the licensee is expected to include NDE flaw sizing uncertainty in their flaw evaluation.
Carl Terry In order to support this position, the staff requests that the BWRVIP provide the following:
1.
Evaluate the components which are covered by BWRVIP I&E guidelines and which are, or may be, subject to volumetric examination methods under the BWRVIP programs.
Identify a component (e.g., core spray piping/header) which generally exhibits a lesser degree of flaw tolerance (i.e., one for which the flaw size which would lead to structural factors not being met is relatively small). Provide an evaluation which demonstrates the structural factors which would be maintained if the predetermined maximum value established for volumetric examination NDE flaw sizing uncertainty were added to the largest flaw (without NDE flaw sizing uncertainty) which would just meet the flaw evaluation structural factors.
2.
Evaluate the components which are covered by BWRVIP I&E guidelines and which are, or may be, subject to surface examination methods under the BWRVIP programs.
Identify a component (e.g., core should vertical welds) which generally exhibits a lesser degree of flaw tolerance (i.e., one for which the flaw size which would lead to structural factors not being met is relatively small). Provide an evaluation which demonstrates the structural factors which would be maintained if the predetermined maximum value established for surface examination NDE flaw sizing uncertainty were added to the largest flaw (without NDE flaw sizing uncertainty) which would just meet the flaw evaluation structural factors.
3.
In light of the observed structural factor reductions from items a. and b. above, discuss the various conservative assumptions (e.g., use of a bounding crack growth rate, lower bound material properties, etc.) which are included in BWRVIP I&E flaw evaluation guidelines. Discuss how these conservatisms support the conclusion that the affect of excluding the predetermined maximum value established for NDE flaw sizing uncertainty is insignificant in the overall flaw evaluation process.
Please contact Matthew Mitchell of my staff at (301) 415-3303 if you have any further questions regarding this subject.
Sincerely,
/RA/
Stephanie Coffin, Chief Vessels & Internals Integrity and Welding Section Materials and Chemical Engineering Branch Division of Engineering Office of Nuclear Reactor Regulation
Enclosure:
As stated cc: BWRVIP Service List
Carl Terry In order to support this position, the staff requests that the BWRVIP provide the following:
1.
Evaluate the components which are covered by BWRVIP I&E guidelines and which are, or may be, subject to volumetric examination methods under the BWRVIP programs.
Identify a component (e.g., core spray piping/header) which generally exhibits a lesser degree of flaw tolerance (i.e., one for which the flaw size which would lead to structural factors not being met is relatively small). Provide an evaluation which demonstrates the structural factors which would be maintained if the predetermined maximum value established for volumetric examination NDE flaw sizing uncertainty were added to the largest flaw (without NDE flaw sizing uncertainty) which would just meet the flaw evaluation structural factors.
2.
Evaluate the components which are covered by BWRVIP I&E guidelines and which are, or may be, subject to surface examination methods under the BWRVIP programs.
Identify a component (e.g., core should vertical welds) which generally exhibits a lesser degree of flaw tolerance (i.e., one for which the flaw size which would lead to structural factors not being met is relatively small). Provide an evaluation which demonstrates the structural factors which would be maintained if the predetermined maximum value established for surface examination NDE flaw sizing uncertainty were added to the largest flaw (without NDE flaw sizing uncertainty) which would just meet the flaw evaluation structural factors.
3.
In light of the observed structural factor reductions from items a. and b. above, discuss the various conservative assumptions (e.g., use of a bounding crack growth rate, lower bound material properties, etc.) which are included in BWRVIP I&E flaw evaluation guidelines. Discuss how these conservatisms support the conclusion that the affect of excluding the predetermined maximum value established for NDE flaw sizing uncertainty is insignificant in the overall flaw evaluation process.
Please contact Matthew Mitchell of my staff at (301) 415-3303 if you have any further questions regarding this subject.
Sincerely,
/RA/
Stephanie Coffin, Chief Vessels & Internals Integrity and Welding Section Materials and Chemical Engineering Branch Division of Engineering Office of Nuclear Reactor Regulation
Enclosure:
As stated cc: BWRVIP Service List Distribution:
EMCB R/F CE Moyer W Cullen ML030920682 INDICATE IN BOX: C=COPY W/O ATTACHMENT/ENCLOSURE, E=COPY W/ATT/ENCL, N=NO COPY OFFICE EMCB:DE EMCB:DE EMCB:DE EMCB:DE NAME MKKhanna MMitchell TChan SCoffin DATE 03/ 21 /2003 03/ 21 /2003 03/ 25 /2003 03/ 25 /2003 OFFICIAL RECORD COPY
cc:
terryc@nimo.com vaughn.wagoner@cplc.com rldyle@southernco.com richard.ciemiewicz@exeloncorp.com Gary.Park@nmcco.com johna.wilson@exeloncorp.com bcarter@epri.com tmulford@epri.com rpathani@epri.com kwolfe@epri.com ldsteine@epri.com Bill Eaton, BWRVIP Vice Chairman General Manager, Plant Operations Entergy Operations, Inc.
Grand Gulf Nuclear Station PO BOX 756, Waterloo Rd.
Port Gibson, MS 39150-0756 Robin Dyle, Technical Chairman BWRVIP Assessment Committee Southern Nuclear Operating Co.
40 Inverness Center Parkway Birmingham, AL 35242 H. Lewis Sumner, Executive Chair BWRVIP Mitigation Committee Vice President, Hatch Project Southern Nuclear Operating Co.
M/S BIN B051, PO BOX 1295 40 Inverness Center Parkway Birmingham, AL 35242-4809 Richard Ciemiewicz, Technical Vice Chair BWRVIP Assessment Committee Exelon Corp.
Peach Bottom Atomic Power Station M/S SMB3-6 1848 Lay Road Delta, PA 17314-9032 Michael McMahan, Executive Chair BWRVIP Assessment Committee Vice President, Project and Outage Mgmnt.
Exelon Corporation Cornerstone II at Cantera 4300 Winfield Rd.
Warrenville, IL 60555-4012 Gary Park, Technical Chairman BWRVIP Inspection Focus Group Nuclear Management Co.
DAEC Plant Support Center 3313 DAEC Road Palo, IA 52324-9646 Vaughn Wagoner, Technical Chair BWRVIP Integration Committee Progress Energy One Hannover Square 9C1 P.O. Box 1551 Raleigh, NC 27612 John Wilson, Technical Chair BWRVIP Mitigation Committee Nuclear Chemistry Manager Exelon Corporation Cornerstone II at Cantera 4300 Winfield Rd.
Warrenville, IL 60555-4012 Al Wrape, Executive Chair BWRVIP Integration Committee General Manager, Nuclear Engrg.
PPL Susquehanna, LLC 2 N 9th Street Allentown, PA 18101-1139 Denver Atwood, Technical Chair BWRVIP Repair Focus Group Southern Nuclear Operating Co.
Post Office Box 1295 40 Inverness Center Parkway Birmingham, AL 35201
Robert Carter, EPRI BWRVIP Assessment Manager Greg Selby, EPRI BWRVIP Inspection Manager EPRI NDE Center P. O. Box 217097 1300 W. T. Harris Blvd.
Charlotte, NC 28221 Tom Mulford, EPRI BWRVIP Integration Manager Raj Pathania, EPRI BWRVIP Mitigation Manager Ken Wolfe, EPRI BWRVIP Repair Manager Larry Steinert, EPRI BWRVIP Electric Power Research Institute P. O. Box 10412 3412 Hillview Ave.
Palo Alto, CA 94303