ML050840080
| ML050840080 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 05/21/2004 |
| From: | - No Known Affiliation |
| To: | NRC/OCM |
| References | |
| BL-01-001, BL-02-002, FOIA/PA-2004-0282 | |
| Download: ML050840080 (2) | |
Text
0 Gregory Cwalina - PBNP.doc
_Page 1
May 21,2004 4 )
fat To: Nuclear Regulatory CommisL -
In view of the NRC's lack of performance in dealing with safety issues (as identified in the recent GAO assessment), such as the Davis Besse RPV head degradation, and lack of assertiveness in ensuring that PBNP operates without recurring safety significant events, I am compelled to communicate this issue.
I wish to express a safety concern about the operation of the Point Beach Nuclear Plant.
NRC Bulletin 2001-01 was issued when circumferential cracks were discovered in the Alloy 600 CRDM head penetration nozzles and in the Alloy 182 J-groove welds at several PWRs. Also, as a result of the severe head corrosion discovered at the Davis-Besse Nuclear Power 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 specified the frequency and type of 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 NRC Order EA-03-009, PBNP performed bare metal visual inspections and "underhead" "UT' examinations of the vessel head penetration nozzles during the Unit 1 spring 2004 refueling outage.
The "UT' examinations revealed an anomaly in the root of the penetration 26 " groove weld. The anomaly was believed to be manufacturing related. The presence of the indication lead to the performance of a surface penetrant (PIT) examination of the penetration 26 "J" groove weld. 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 re-examination revealed the indications had depth. The indications were not sized or characterized. The indications were deemed to be not acceptable for 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 of the Inconel weld material.
Since the surface PT examination was not required by NRC Order EA-03-009, the 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.
My concern is that the UT examination was not capable of finding the damaged 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 RPV head.
In the interest of public safety, please provide technical justification why the NRC has MIformaabon in Mis record was deleted in accordance with fth Freedom of Informamon AcLex empo
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.E g not required PBNP to 'PT" a reasonable sample of the other high stress penetration's "J" groove welds (outer periphery penetrations, and the mechanically straightened penetrations during manufacture of the subject head). Please provide your response in writing, and include the technical justification for ignoring the potential for Inconel 182 cracking that was not detectable by the mandated examinations.
Your prompt attention to this issue would be appreciated since the NMC is planning on installing the degraded RPV head and returning PBNP Unit 1 to service in the immediate future.
Sincerely U_ I cc:
Chairman Nils J. Diaz
- Representative Thomas E. Petri Senator Herb Kohl Senator Russell Feingold