ML050830452
| ML050830452 | |
| Person / Time | |
|---|---|
| Site: | Point Beach  |
| Issue date: | 06/03/2004 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| References | |
| FOIA/PA-2004-0282, NRR-2004-A-0026 | |
| Download: ML050830452 (6) | |
Text
LlM ITELIE ATlOl L NRR-2004-A-0026 ALLEGATION REVIEW BOARD BRIEFING AND MEETING
SUMMARY
FACILITY: Point Beach TAC NUMBER: MC3234 RECEIVED: May 25-27, 2004 (NRR) 150 Day Date: October 21, 2004 TYPE OF ARB: Initial ARB Meeting PURPOSE OF ARB: To discuss allegation resolution DATE OF ARB: June 3, 2004 BACKGROUND FOR CONCERNS: First revised NRC Order EA-03-009 required specific Inspections of the reactor pressure vessel head and associated penetration nozzles at PWRs. The frequency of required inspections depend upon a calculated susceptibility to primary water stress corrosion cracking (PWSSC). However, all licensees are required to perform a visual Inspection and either (1)ultrasonic testing (UT), (2) eddy current or dye penetrant testing (PT), or (3) a combination of (1) and (2). To comply with Order EA-03; 009, Point Beach performed bare metal visual examinations and UT examinations of the vessel head penetration nozzles.
CONCERN 1:
A UT examination of Point Beach Nuclear Plant (PBNP) Unit 1 penetration 26 "J" groove weld was not capable of finding the damage discovered within (as identified by a surface penetrant test), and that PWSCC damage probably exists in other penetration "J" groove welds In the PBNP reactor pressure vessel head. Despite the results of the surface PT exam, the licensee will not pursue the PT examinations of other "J" groove welds because of the potential for finding additional evidence of PWSCC damage. The NRC should provide a "technical justification why the NRC has not required PBNP to "PT" a reasonable sample of other high stress penetration's "J" groove welds ..."
CONCERN 2:
A Point Beach reactor vessel head nozzle fracture mechanics analysis was performed to support a code relief request (verbally granted to PBNP on May 26, 2004) for the temporary repair of Unit 1 penetration 26. The fracture mechanics analysis assumed I INRR-2004-A-0026 ID D1555)fmi1§T~LEBTiON MTEML_
7 I'Mf DBUDTIN-D Dl Nl 9 I )ITT flaw size for PBNP Is arbitrary and "suspiciously small" in order to allow achieving a calculated operational life greater than a plant operational cycle. The NRC should provide written justification that the assumed PBNP flaw size contained in the fracture mechanics analyses for the temporary repair is In fact bounding for any and all potential existing flaws.
I. BACKGROUND:
On May 21, 2004, a letter, describing concern 1 was transmitted to the NRC's "allegation" web page by a concerned individual (Cl). The letter indicated that the Cl also copied Senators Thomas Petri, Herb Kohl and Chairman Nils Diaz. Since the issue was focused specifically on Point Beach's reactor vessel head penetration nozzles, Region IlIl took immediate responsibility for the issue and convened an emergency ARB on the same day. The RIII-ARB determined that there was not any immediate threat to public health or safety and the ARB concluded that it was acceptable to forward the issue to the Point Beach'Nuclbar Plant (PBNP) licensee. The RIII-ARB decided that it would request the licensee to provide its (A)technical basis for not conducting additional dye penetrant (PT) examinations on other penetrations; and (B) request the licensee to provide a characterization of the significance of previously identified "J" groove weld cracks as to whether or not a significant condition adverse to quality existed. Rill staff communicated with the licensees and identified some concerns and considerations that NRR staff may wish to consider in its review of the Cl's concerns.
Subsequent discussion between Rill and NRR Office Allegation Coordinators determined that the concern should be referred to NRR based on their involvement in pending licensing actions that may have relevancy to the Cl's issues, NRR's role in the Code relief, and possible generic considerations since NRC Order EA-03-009, "Issuance of Order Establishing Interim Inspection Requirements for Reactor Pressure Vessel Heads at PWRs" was directed at all PWRs. The Cl's May 21, 2004, letter, to the NRC, stated:
NRC Bulletin 2001-01 was issued when circumferential cracks were discovered in Alloy 600 CRDM penetration nozzles and in the Alloy 182, "J" groove welds at several PWRs. As a result of the severe head corrosion discovered at the Davis-Besse station, the NRC issued Bulletin 2002-02, which requested that PWRs determine if supplementary reactor vessel examinations are necessary. Finally, the NRC issued Order EA-03-009, which specifibd'the ifrequencya~nd type of PWR reactor vessel head examinations that were necessary to ensure that plant operations do not pose undue risk to the public health and safety. To comply with Order EA-03-009, Point Beach performed bare metal visual examinations and under-head UT examinations of the vessel head penetration nozzles during the Unit 1 Spring 2004 refueling outage.
The Point Beach UT examinations revealed an anomaly in the root of the penetration 26 "J" groove weld. The anomaly was believed to be manufacturing related. The presence of the indication lead to the performance of a surface
[dye penetrant] (PT) examination of penetration 26 uJ" groove welds. The PT examination was not required by NRC Order EA-03-009. The PT examination revealed numerous crack like surface indications. Follow-up grinding and reexamination revealed the indications had depth. The indications were not sized or characterized. The indications were deemed to be not acceptable for
, . NRR-2004-A-0026 LIft1DDTRIB ENSUflVES EALrCTrAT 9jMA 1g
JL1M'D)7 1131IvUT~tNSITIVE I A L E D continued operation. The indications were not detectable with the UT exam that was performed to comply with NRC Order EA-03-009. Although not identical to other industry experience, the indications are likely PWSCC [primary water stress corrosion cracking] of the Inconel weld material. Since the surface PT examination was not required by NRC Order EA-03-009, NMC is not performing additional PT examinations of any of the other RPV head penetrations. The NMC will obviously not pursue the PT examinations in view of the potential for finding additional evidence of PWSCC damage.
Further, the Cl stated the concern is that the UT examination was not capable of finding the damage discovered within the penetration 26 "J" groove weld, and that PWSCC damage probably exists in other penetration "J" groove welds in the PBNP Unit 1 reactor pressure vessel head. The Cl also requested that the NRC staff: "provide justification why the NRC has not required PBNP to PT a reasonable sample of the other high stress penetrations NJ" groove welds (outer periphery penetrations and the mechanically straightened penetrations during manufacture of the subject head)." Additionally, the Cl asked the NRC staff to provide "technical justification for ignoring the potential for Inconel 182 cracking that was not detectable by the mandated examinations."
On May 27, 2004, the same Cl transmitted a second concern to the NRC allegations e-mail address. That one page transmittal stated:
PBNP has performed a temporary repair of penetration 26 in the Unit 1 RPV head. The NRC is involved in approving this repair [an NRC Code relief request was verbally granted to PBNP on May 26, 2004]. It again appears that neither the NRC nor the NMC is being assertive in ensuring the safety of the public.
Thus, I am communicating the following concern. Fracture mechanics analyses have been used to justify the acceptability of the repair. The limiting analysis indicates that the repair is good for approximately 1.5 years of operation. A PBNP operational cycle is approximately 1.3 years. Obviously, there is little margin provided with the PBNP repair design. The fracture mechanics analysis is based on assuming an existing crack within the material. The assumed flaw size for PBNP is arbitrary and very small. In fact, suspiciously small to allow achieving a calculated operational life greater than a plant operational cycle.
The Cl requested "written justification that the assumed PBNP flaw size contained in the fracture mechanics analyses for the temporary repair is in fact bounding for any and all potential existing flaws."
NRR contacted the responsible technical branch for their assessment of the issue. In a June 2, 2004, e-mail, DE staff concluded, "there is no startup, safety or compliance issue if PBNP performed its inspection in accordance with the NRC Order (or First Revised Order) EA-03-009 and any Order relaxation that NRC may have authorized."
NRR also held discussions with Region III staff. In a June 2, 2004, e-mail, RI1I staff stated:
Current regional staff position is that from a purely technical standpoint it would be prudent to expand the sample to at least one or two of the other penetrations that were possibly repaired during original construction. Although we do not NRR-2004-A-0026 X IMVITED DISTRIBUTIONM SENV IMWEALLEGATIONIVIAE AL /
believe a through-wall crack is very likely during the next cycle, we do not guarantee it will not occur. However, we do agree that if it should occur, the expected result (limited to some through wall leakage) does not have safety significant impact. There is no concern about structural integrity of the nozzle or possible ejection. In addition, this expansion is not required by either the ASME code or the Order. (The Order was not focused on or intended for this type of cracking problem.) The regulatory driver with respect to extent of condition would be 10 CFR 50, Appendix B, Criterion XVI with regard to the licensee taking actions to prevent recurrence for a significant condition adverse to quality.
However, without an actual example where the licensee failed to prevent recurrence, at this point we don't believe we could cite the licensee with a violation. Licensee extent of condition has been discussed with the licensee at the senior management level and the licensee declined to expand the sample.
We were advised by NRR management not to press any harder based upon lack
- of safety significance and negative safety impact if the licensee ended up grinding on numerous indications on the head penetrations. Without NRR support, we did not intend to press it any further.
Therefore, while we would prefer the licensee to expand the sample, we don't think we have sufficient regulatory or safety basis to require them to do so. With respect to the licensee's allegation response, knowing what they could have said to provide better basis, we don't think they did a very good job at addressing the concerns in their response letter... We do not have a Region IlIl startup concern regarding Point Beach, however I believe that during your ARB you should
- reverify that opinion with NRR to ensure one last time that we are all agreed.
II. REGULATORY REQUIREMENT(S):
10 CFR 50.55a, "Codes and Standards." The NRC deemed it appropriate to establish a clear regulatory framework pending the revision of 10 CFR 50.55a. As a result, it issued NRC Order EA-03-009 which imposed enhanced requirements for PWR licensees to inspect RPV heads and related penetration nozzles pending the revision of 10 CFR 50.55a. The requirements of the NRC Order EA-03-009 were immediately effective and were expected to remain in place until superceded by changes to 10 CFR 50.55a.
10 CFR 50, Appendix B, Criterion XVI, "Corrective Action."
Ill. SAFETY SIGNIFICANCE AND BASIS: LOW NRC Division of Engineering staff stated that if the licensee performs its RPV head examinations in accordance with the provisions of Order EA-03-009, the NRC considers those licensee actions to be adequate. Therefore, there is no compliance issue. The intent of the order requirements was to preclude the potential for the catastrophic failure of a RVH penetration nozzle as a result of PWSCC induced circumferential cracking and to minimize the potential for leakage. Furthermore, compliance with the Order provides reasonable assurance of public health and safety with respect to RPV upper head penetration examinations.
- NRR-2004-A-0026 LIMITED-DISRBUTION- SENSITIVEPLLEGj A ,0NMATlIAL.,
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The staff's verbal authorization (May 26, 2004) that was given with respect to the relief request was based on a technical review that determined the fracture mechanics analysis (including assumed flaw size) was adequate.
IV. TECHNICAL REVIEW PRIORITY AND BASIS: LOW Based on the above safety significance.
V. ACTIONS:
A. PROPOSED INVESTIGATIONS, PRIORITY LEVEL: NO B. REFERRAL: NO C. PROPOSED INSPECTIONS AND DUE DATES: NONE -
D. OTHER ACTIONS:
Input to closure letter from EMCB. Due date: June 18, 2004 (Due date may change because of associated Green Ticket and public meeting regarding start-up at PBNP).
Green Ticket G20040361 NRR Due Date - June 7, 2004 TAC MC3315*Unit #1 TAC MC3316.Unit #2 VI. NON NRR ISSUES (OGC, OE, REGION, ETC.) - N/A
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,LlUpdlTRIBUla,-,SENSIT-I'VGN-M !(Delta I -A-ALLEGATION REVIEW BOARD SECTION ARB DECISION (and comments):
The ARB agrees with the safety significance, technical review priority, and proposed resolution plan.
ARB ATTENDANCE ARB CHAIRMAN: T. Quay ARB MEMBER: E. Hackett ALLEGATION COORDINATOR: G. Cwalina ALLEGATION COORDINATOR: J. Petroslno ALLEGATION ASSISTANT: J. Crutchley 01 REPRESENTATIVE(S): M. Fahey OGC REPRESENTATIVE(S): G. Longo, H. McGurren IPSB LEAD REVIEWER: F. Talbot TECH. BRANCH LEAD REVIEWER: T. Chan RECORDING SECRETARY: K. Richards ADDITIONAL PARTICIPANTS: H. Chernoff, D. Thatcher, R. Barnes, D. Hills-RIII, M. Holmberg-RIII DISTRIBUTION:
G. Caputo, 01 S. Langan, Ol L. Raghavan R. Barrett D. Hills J. Heller M. Holmberg G:\DIPM\Allegations\2004-26\Initial NRR ARBBriefingSheet-2004-0026.wpd NRR-2004-A-0026 LIt DlDlTIBUTION - SENSIIVE GTERIA