ML13336A290
| ML13336A290 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 10/11/1990 |
| From: | Tatum J Office of Nuclear Reactor Regulation |
| To: | Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 9010310088 | |
| Download: ML13336A290 (9) | |
Text
0' October 11, 1990 Docket No. 50-206 FACILITY:
San Onofre Nuclear Generating Station, Unit No. 1 LICENSEE:
Southern California Edison Company
SUBJECT:
SUMMARY
OF MEETING HELD IN ROCKVILLE ON OCTOBER. 3, 1990, RE:
THERMAL SHIELD REPAIR On October 3, 1990, the NRC staff met with representatives of Southern California Edison Company (SCE or the licensee) to discuss the progress being made on the thermal shield repair. Persons attending the meeting are identified in Enclosure 1.
During the meeting, the licensee presented information regarding projected and actual dose estimates (Enclosure 2), as-found conditions (Enclosure 3),
miscellaneous topics (Enclosure 4), and current schedules for completing work and making final submittals to the NRC.
The licensee plans to complete the thermal shield repair work around mid-November and has requested NRC approval of the repair and proposed license condition by November 1, 1990, to support this schedule. The licensee intends to make the final submittals by about October 19, 1990. These submittals, however, should have minimal impact on the current NRC review effort.
Original signed by James E. Tatum, Project Manager Project Directorate V Division of Reactor Projects -
- III, IV, V and Special Projects
Enclosures:
As stated cc w/enclosures:
See next page DISTRIBUTION DocketFileT NRC & Local PDRs FMiraglia JPartlow DCrutchfield MVirgilio PDV Reading JDyer JTatum OGC EJordan DTerao JRajan CSellers CHinson ACRS (10)
MSlosson 9010310088 901011 PDR ADOCK 05000206 P
PNU OFC
- DRSP:P V:PM
- DRSP:PDV:(A)D NAME m:pm JDy f-.
DATE :/o/ 7190 10/
/90 OFFICIAL RECORD COPY Document Name:
THERMAL SHIELD RPR MTG MIN
Mr. Harold B. Ray San Onofre Nuclear Generating Southern California Edison Company Station, Unit No. 1 cc David R. Pigott Mr. Richard J. Kosiba, Project Manager Orrick, Herrington & Sutcliffe Bechtel Power Corporation 600 Montgomery Street 12440 E. Imperial Highway San Francisco, California 94111 Norwalk, California 90650 Mr. Robert G. Lacy Mr. Phil Johnson Manager, Nuclear U.S. Nuclear Regulatory Commission San Diego Gas & Electric Company Region V P. 0. Box 1831 1450 Maria Lane, Suite 210 San Diego, California. 92112 Walnut Creek, California 94596 Resident Inspector/San Onofre NPS U.S. NRC P. 0. Box 4329 San Clemente, California 92672 Mayor City of San Clemente San Clemente, California 92672 Chairman Board of Supervisors County of San Diego 1600 Pacific Highway Room 335 San Diego, California 92101 Regional Administrator, Region V U.S. Nuclear Regulatory Commission 1450 Maria Lane, Suite 210 Walnut Creek, California 94596 Mr. John Hickman Senior Health Physicist Environmental Radioactive Management Unit Environmental Management Branch State Department of Health Services 714 P Street, Room 616 Sacramento, California 95814 Mr. Don Womeldorf Chief, Environmental Management California Department of Health 714 P Street, Room 616 Sacramento, California 95814
ENCLOSURE 1 ATTENDEES NRC SCE J. Tatum J. Reilly D. Terao F. Nandy J. Rajan R. Ornelas C. Sellers C. Hinson P. Chen (NRC Consultant)
ENCLOSURE 2 THERMAL SHIELD MODIFICATION EXPOSURE PROJECTIONS PERSON - REM JOB PHASE Estimated Present Projected Total Initial Set-Up 5.914 3.558 3.558 Core Barrel Lift 2.558 1.380 1.380 Modification Work 67.676 26.408 48.400 74.808 Recovery 9:604 5.778 5.778 TOTALS 85.752 31.346 54.178 85.524 DETAIL OF MODIFICATION PHASE PERSON - REM WORK GROUP Estimated Present Pro ected Total KWU 38.161 11.595 21.258 32.853 HP 17.760 5.113 9.374 14.487 RMC 3.915 0.180 0.330 0.510 FME 5.760 0.972 1.782 2.754
ENCLOSURE 3 EVALUATION OF THE AS FOUND CONDITION SONGS 1 THERMAL SHIELD In February 1989, Westinghouse issued WCAP-12148, "Engineering Evaluation of the SONGS 1 Thermal Shield Supports."
The primary objective of this report was to demonstrate that SONGS 1 could return to service for an additional fuel cycle without experiencing additional support system degradation. At that time, Westinghouse concluded that:
- 1) The 124 degree flexure would remain intact throughout the next 18 month cycle of operation,
- 2) The hidden bolts and the top long bolts in the 0 and 240 degree support blocks are broken or cracked or can be expected to fail in the future,
- 3) There was a possibility that the three top bolts in the 300 degree block are damaged or are expected to be damaged in the future,
- 4) All the lower bolts and dowel pins were still intact and functional at the beginning of the cycle.
During the summer of 1990, Southern California Edison performed an inspection of the SONGS 1 lower reactor internals and the pressure vessel.
Results of this inspection were transmitted to Westinghouse and are summarized as follows:
- 1) The 124 degree flexure remained undamaged confirming the Westinghouse analyses performed as part of the return to power assessment performed in February 1989.
- 2) The top bolts in the 0 and 240 degree blocks were broken as predicted in February 1989. All the bolts in the 240 degree block and all the bolts except one (A3) in the 0 degree block were reported to be broken.
- 3) One out of two long top bolts were broken at the 300 degree block location as predicted in February 1989. Moreover, the one hidden bolt was also reported to be broken.
- 4) One out of two long bolts were broken at the 120 degree location.
It should be noted that this was not predicted as long as the 0 and 240 degree blocks did not have substantial wear or the dowel pins wear not protruding. (The analysis assumed -.045 inch vertical gap between the T/S and support block ledge.) In addition, the hidden bolts were reported to be broken at the 60 and 180 degree locations.
- 5) If the long bolt holes drilled through the thermal shield were parallel and the threaded portion in core barrel was on a radial axis, a bending moment would have been induced into the bolts that was not considered in the analysis. This additional moment could have accelerated the fatigue failure of the bolts.
-2 Current Evaluation
- 1) The current evaluation of the flexures was baselined to the failure history of the flexures and not the support blocks.
- 2) The ASME Code design fatigue curves were used to qualify the flexure and the support block designs. The evaluation performed in 1989 for the lower supports used the failure fatigue curves.
- 3) The F.I.V. loads for the new lower support blocks, bolts and dowel pins were not scaled. Only the flexure web F.I.V. loads were scaled by the baseline factor of.685.
In general, the analytical predictions made in February 1989 are consistent with the finding from the most recent SONGS 1 reactor internals inspection.
EVLASFND.MM2
1989 As Found Conditiort of the Support Block Fasteners 0
60 120 180 j
2400 3000 Bolt F4 G6 Broken Broken F8 Broken A3 A9 Pin B4 Pin B8 A5 A7 2.5" 0-
- 2.5 4
9 O94C I~
T________
1990 As Found Condition of the SUppOrt Block Fasteners
[_
80 1200 180 J 2400 j
3000 Bolt F4 Broken Galled?
Broken Broken Broken G6 Broken Broken Broken Broken Broken Head/Bolt F8 Broken Galled?
Broken A3 Broken A9 Broken Broken Pin 84 Loose Loose Loose Pin B8 Loose Loose A5 A7
- 2.5"
!0"-25 4
9
- 2.9.5" II
-o I3 V. T T.
ENCLOSURE 4 MISCELLANEOUS TOPICS Torque testing of fasteners was discussed; the licensee will submit additional information for staff consideration.
The need to conduct corrosion testing of locking cup materials was discussed. The staff stated that the licensee should conduct such testing or provide representative materials to the NRC for testing purposes.
The licensee discussed the lower support block bolt hole misalignment problems that have been encountered and planned resolution.
In response to questions asked by the NRC staff, the licensee stated that the following additional information would be submitted to the NRC:
- a. Total outage dose broken down by project.
- b. Final Westinghouse report (WCAP) related to the thermal shield repair work.
The licensee discussed the schedules for submitting the following information to the NRC which the licensee had previously committed to provide:
- a. Declassify certain information contained in WCAP 121148 and WCAP 12644 by approximately October 12, 1990.
- b. Provide additional information regarding the analyses in WCAP 12248 and WCAP 12644 by approximately October 19, 1990.
- c. Submit the revised lower block design drawings by approximately October 12, 1990.
- d. Provide evaluation of alignment issues by approximately October 19, 1990.
- e. Provide evaluation of as-found condition by approximately October 19, 1990.
- f. Provide information related to bolt torque testing by approximately October 12, 1990.