ML20062H356
| ML20062H356 | |
| Person / Time | |
|---|---|
| Site: | Prairie Island  |
| Issue date: | 12/12/1979 |
| From: | Grotenhuis M Office of Nuclear Reactor Regulation |
| To: | Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML20062H358 | List: |
| References | |
| NUDOCS 7912210008 | |
| Download: ML20062H356 (4) | |
Text
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[(7, e, 'i NUCLEAR REGULATORY COMMISSION UNITED STATES
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WASWNG TON. D. C. 20555 d
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Docket Nos. 50-282 p
and 50-306 LICENSEE: Northern States Power Company (NSP)
FACILITY: Prairie Island Nuclear Generating Plant Unit Nos. I and 2
SUBJECT:
SUMMARY
OF MEETING HELD ON NOVEMBER 26, 1979 TO DISCUSS THE REACTOR VESSEL UNDERCLAD CRACKING PROBLEM On November 26, 1979, representatives of Westinghouse (W) and NSP met with the staff to present the details of underclad cracking probTems overseas in-f Franatome reactor vessel nozzles and the status of the review of the similar Prairie Island Plant vessels also made by Framatome.
Background
On September 25, 1979 Westinghouse notified the NRC by phone that cracks had been discovered in several reactor vessel nozzles that had been manufactured in France. Since the Prairie Island Plant reactor vessels were manufactured by Framatome in France, we were potentially concerned that they could be subject to the same cracking problem. On September 28, 1979, on the basis of a memo from B. Grimes to A. Schwencer, a phone call was made to NSP to alert them to our concern about this potential problem. NSP was already aware of the problem in a general way and was proceeding to look into the matter with Westinghouse.
On October 24, 1979 a memo was issued to the Connissioners (Attachment 2),
reporting the information that was known to the staff at that time.
On Novetter 16, 1979 the staff called this meeting for November 26, 1979 to update our understanding of the problem to ger a status report, and to discuss the future plans of Westinghouse and NSP regarding this matter as it specifically related to the Prairie Island Plant units.
Meeting Sunmary, The meeting was opened with a presentation by the Westinghouse staff. They indicated that Westinghouse was notified by Framatore that base metal cracking was discovered in several reactor vessel nozzles under the stainless steel cladding.
The cause of the cracking is believed to be hydrogen embrittlenent.
Similar base metal cracking was also fcund beneath the cladding on steam generator tube sheets. This underclad cracking proble<n affected vessels manufactured by Framatcme using a certain welding procedure. The Prairie Island reactor vessels were manufactured by Framatore, as were the offshore power system (OPS) vessels.
The Westingncase presentation included an outline of the pr:-Jea, an action plan for resolutten, early results of some investigations and tests tra has been perfor ed on some CPS reactor vessel nozzles, a schedule of de Mnq ISI procedures, results of a broad study of reactor vessels manufactured by.ther st.;91ers, and the future laboratory prcgram. Details were outlines in viewgraphs (See Attachner? ?),
and pnotos of the early test resuits were circulated.
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1L 2-i There was a detailed discussion on each of the areas with all questions posed.
by the staff answered. Considerable time was spent in reviewing the photographs of various specimens.
t Following this Westinghouse presented plans and some preliminary results of fracture mech 30ics studies of the Prairie Island Plant.
Early results indicated I
that flaws up to 1/2 inch of present wwld meet all accident requirements without loss of vessel integrity. As noted below, NSP test conducted in 1977 showed no evidence of cracking.
In summary, a Westinghouse staff action plan is underway and based on samples 1
taken frot the OPS nozzles and the preliminary facture mechanics studies, the problem was considered under control with no immediate concern for loss of integrity of the reactor coolant procedure boundary for the Prairie Island RCS.
Following the Westinghouse presentation of NSP staff revicwe! its ples. There i
i pland consisted primarily cf conducting the new ISI tests daveloped b; the Westinghouse program.
It is expected that these additional ISI tests Will be performed on Unit I during its Spring 1980 refueling outage.
NSP conducted on inservice inspection of one outlet nozzle from each vessel in
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1977 and found no evidence of r, racking. A code fracture mechanics analysis of i
all reactor vessel nozzles will be performed.
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i Conclusion l
The staff concluded that the Westinghouse was proceeding in an appropriate measure and that no staff action was required at this t.ime.
Westinghouse will 4
provide a written account of their presentation in about ten days. HSP will i
file a written account of their plans in about fifteen days. The staff will review these plans and comment further as necessary.
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Marshall Grotent~uis, Project Manager Operating Reactors Branch No. 1 Division of Gperating Reactors t
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3R 2m Meeting Summary for Northern States Power Company Docket Files f4RC PDR Gerald Charnoff, Esquire Local PDR Shaw, Pittman, Potts and Trewbridge ORbl Reading 1800 M Street, N.W.
NRR Reading Washington, D. C.
20036 H. Denton E. Case Ms. Terry Hoffman D. Eisenhut Executive Director R. Tedesco Minnesota Pollution Control Agency G. Zecn 1935 W. County Road B2 B. Grimes Roseville, Minnesota 55113 W. Gammill L. Shao The Environmental Conservation Library J. Miller Minneapolis Public Library R. Vollmer 300 Nicollet Mall T. J. Carter Minneapolis, Minnesota 55401 A. Schwencer O. Ziemann Mr. F. P. Tierney, Plant Manager P. Cneck Prairie Island Nuclear Generating Plant G. Lainas Northern States Power Company D. Crutchfield Route 2
- 8. Grimes Welch, Minnesota 55089 T. Ippolito R. Reid Joclyn F. Olson, Esquire V. iloonan Scecial Assistant Attorney General G. K.11gnton Minnesota Pollution Control Agency D. Brinkman 1935 W. County Road 82 Project Manager Roseville, fiinnesota 55113 OELO OI&E (3)
Robert L. Nybo, Jr., Chairnan C. Parrish/P. Kreutzer Minnesota-Wisconsin Boundary Area ACRS (16)
Ccre.ission I
f.RC Participants 619 Second Street N5IC Hudson, Wisconsin 54016 TERA Licensee Clarence D. Fierabend Short Service List U. S. Nuclear Regulatory Ccomission P. O. Box 37 b
Red Wing. Minnesota 55065 I
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ATTACHMENT I ATTENDANCE NAMES FACILITY Marshall Grotenhuis NRC/00R/0RB-1 Al Taboada NRC/ DOR Candee L. Gattshall Westinghouse Nuclear Safety (NTO)
William J. Collins NRC/I&E Tech. Programs T. R. Mager WestinghouseMet.&NDE(NTD)
J. N. Chirigos Westinghouse Met. & NDE (UTD)
Phillip J. Krumpos Northern States Power Company David Musolf Northern States Power Company J. Sero Westinghouse Paul C. Parris Washington University W. S. Hazelton NRC/ DOR / Engineering Branch Richard E. Johnson NRC/ DOR / Engineering Branch Robert A. Hermann NRC/ DOR / Engineering Branch P. N. Randall NRC/ DOR / Engineering Branch C. W. Rowland Westinghouse E. G. Igne NRC/ACRS R. Gamble NRC/ Materials Engineering Branch b