ML20207G180

Summary of 861217 Meeting W/Util Re Util Request for Relief from Commitment to Inspect Core Support Barrel/Thermal Shield During Cycle 11 Refueling Outage.List of Attendees Encl

ML20207G180
Person / Time
Site:	Fort Calhoun
Issue date:	12/23/1986
From:	Sells D Office of Nuclear Reactor Regulation
To:	Thadani A Office of Nuclear Reactor Regulation
References
NUDOCS 8701060376
Download: ML20207G180 (5)

Text

4 DEC 2 31986 Docket No. 50-285

~ MEMORANDUM FOR: Ashok C. Thadani, Director PWR Project Directorate #8 Division of PWR Licensing-B FROM: Donald E. Sells, Project Manager PWR Project Directorate #8 Division of PWR Licensing-B

SUMMARY

OF MEETING HELD ON DECEMBER 17, 1986 REGARDING CORE SUPPORT BARREL / THERMAL SHIELD On Wednesday, December 17, 1986, a meeting was held between the staff and the Omaha Public Power District (0 PPD). The meeting was held to discuss the recent request by OPPD for relief from its commitment to do a complete core support barrel / thermal shield inspection during the Cycle 11 refueling outage. A list of attendees is enclosed.

After a brief introduction by J. Fisicaro of OPPD, T. Patterson, OPPD, discussed the thermal shield support system at Fort Calhoun and described the '

physical, thermal-hydraulic and design differences found at Fort Calhoun when compared to other Combustion Engineering (CE) plants tha't have or had thermal shields. Specifically, the major differences include 1) one less support lug; .2) fewer positioning pins; 3) use of locking collars vs. locking bars;

4) lower flow in the annulus; 5) lower positioning pins well'below the active core boundary; and 6) smaller delta T across the lower pins.

T. McIvor presented a short discussion of the results of the 1982/83 inspection. The visual inspection was somewhat more extensive than would have been conducted because of the thermal shield support problems that had been discovered at Maine Yankee in 1982. The visual inspection provided a good head-on view of four of the lugs and over half of the positioning pins with an oblique view of the remainder. There was no indication of any degradation in the welds nor around the support system components.

Subsequent to this visual inspection, the core support barrel / thermal shield damage was detected at St. Lucie Plant, Unit No. 1, and Millstone Unit 2. A great deal of analysis was performed by CE and the results of the St. Lucie analysis were provided to the staff in a proprietary report in the fall of 1984. This report is available through the St. Lucie Project Manager. It was determined that one of the frequency shifts noted in the reduction of internal vibration monitoring data showed that the thermal shield was in fact decoupled and could have been used as the warning signal that problems were developing.

Unfortunately, this was after-the-fact knowledge and was of no benefit to either St. Lucie 1 or Millstone 2.

DOho$0k$85 PDR

B. Longo, CE, in his presentation went over the resalts of the St. Lucie analysis and then presented Fort Calhoun data, including data taken at 0%

power in July 1986. He concluded that there is no evidence of a decoupling occurring at Fort Calhoun and therefore a St. Lucie or Millstone type failure is not imminent. In fact, the data shows no unexplained frequency shift in the Fort Calhoun data in the critical area.

Based on this information OPPD, stated their confidence that Fort Calhoun has not lost pre-load, a necessary failure prior to thermal shield support failure, ,

and that inspection of the core support. barrel / thermal shield should be conducted on the normal 10 year ISI inspection cycle.

The staff agreed in principle with that position, but pointed out that meeting more than normal ISI requirements at the next 10 year inspection may be appropriate. The staff indicated that the results of the meeting would be documented in the near future and that they would be likely to approve the OPPD request with requests for further action in some areas, such as more detailed inspection than required in the ISI program, in the future.

ongmalsigre oy Donald E. Sells, Project Manager PWR Project Directorate #8 Division of PWR Licensing-B

Enclosure:

List of Attendees cc w/ enclosure:

See next page i

f PBD# 8 PBD#8 er Sells;cf AThadani 1/ /86 12/)]/86 12/ 86

LIST OF ATTENDEES DECEMBER-17, 1986 CORE SUPPORT BARREL / THERMAL SHIELD MEEING NRC OPPD C. Y. Cheng H isicaro M. Hum R. Longo (CE)

L. Marsh D. Rollins W. Paulson T. Patterson J.-Rajan J. Mullooly (CE)'

C. D. Sellers T. McIvor D. Sells A. Thadani M. Wambsganss 2

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Mr. R. L.Andrews Fort Calhoun Station Omaha Public Power District Unit No. 1 cc:

Harry H. Voigt, Esq.

LeBoeuf, Lamb, Leiby & MacRae 1333 New Hampshire Avenue, NW Washington, D.C. 20036 Mr. Jack Jensen,-Chairman Washington County Board of Supervisors Blair, Nebraska 68008 Mr. Phillip Harrell, Resident Inspector U.S. Nuclear Regulatory Commission P. O. Box 309 Fort Calhoun, Nebraska ~ 68023 Mr. Charles B. Brinkman, Manager Washington Nuclear Operations C-E Power Systems 7910 Woodmont Avenue Bethesda, Maryland 20814 Regional Administrator, Region IV U.S. Nuclear Regulatory Commission Office of Executive Director for Operations 611 Ryan Plaza Drive,' Suite 1000 Arlington, Texas 76011 Harold Borchert, Director Division of Radiological Health

' Department of Health 301 Centennial Mall, South -

P.O. Box 95007 Lincoln, Nebraska 68509

.1 M G 0 /(o MEETING

SUMMARY

DISTRIBUTION

-PWR PROJECT DIRECTORATE #8 Docket "I POI, Fi y L PDR PBD#8 Rdg AThadani PKreutzer OELD EJordan BGrimes ACRS-10 NRC Participants CYCheng MHum LMarsh-WPaulson JRajan CSellers AThadani DSe,lls

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