ML19208A811
| ML19208A811 | |
| Person / Time | |
|---|---|
| Site: | Brunswick  |
| Issue date: | 08/10/1979 |
| From: | Furr B CAROLINA POWER & LIGHT CO. |
| To: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| NG-3513-(B), NUDOCS 7909170540 | |
| Download: ML19208A811 (4) | |
Text
1 CD&L" l ' 3','C pipaPower & Light Company s7 August 10, 1979 SERIAL: GD-79-2027 FILE: NG-3513 B Mr. James P. O'Reilly, Director U.S. Nuclear Regulatory Commission Region II 101 Marietta Street, Suite 3100 Atlanta, Georgia 30303 BRUNSWICK STEAM ELECTRIC PLANT, UNIT NOS. 1&2 LICENSE NOS. DPR-71 AND DPR-62 DOCKET NOS. 50-325 AND 50-324 SUPPLEMENT TO IE BULLETIN 79-02
Dear Mr. O'Reilly:
During the recent visit of July 26-27, 1979, of your Mr. Leo Modenos and subsequent telephone conversations between your staff and the Brunswick Steam Electric Plant staff, several concerns were addressed regarding our testing and response to IE Bulletin 79-02.
This supplement is in response to those concerns.
Special Test Procedure, SP-79/22, will be revised to include ultrasonic testing of previously installed wedge anchors to determine length. Thread depth of newly installed wedge anchors will be checked prior to torquing. Self-drilling acceptance criteria will be added (Enclosure 1) to verify / check for proper installation.
UE&C has given verbal confirmation that these tolerances (Enclosure 1) are adequate.
In light of the new acceptance criteria (plug depth and thread engagement) and using anchors vice supports to determine percentages, the following are BSEP's current test results (based on a proposed 100% inspection of anchors for pipe size supports greater than 2 1/2 inches):
Unit No. 1 Unit No. 2 Total 1.
Supports Requiring Inspection 82 78 160 2.
Number of Concrete Anchors 286 276 562 3.
Anchors Not Inspected 176 171 347 4.
Anchors Inspected 110 105 215
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Number Anchors Failed 13 14 27 6.
Failure Rate 11.82%
13.33%
12.56%
7.
Potential Failures, Uninspected Anchors 21 23 44 4
4 8
8.
Anchors Repaired 9.
Anchors Not Repaired 9
10 19 10.
Anchors Not Repaired but Preloaded to 20% Ultimate 8
8 16 11.
Currently Failed Anchors (Not preloaded) 1 2
3 12.
Total Potential Anchor Failure (7 + 11) 22 25 47 12a. Total Potential Anchor Failure (7 + 9) 30 33 63 13.
Potential Anchor Failure Rate (12/2) 7.7%
9.05%
8.36%
13a. Potential Anchor Failure Rate (12a/2) 10.5%
11.96%
11.21%
As a result of the higher failure rate due to the new criteria, testing will be done on all anchors. Due to the increased testing requirements, we aubmit the following schedule for testing completion:
Complete inspection of greater than 2 1/2 inch line size accessible anchors... August 24, 1979.
Complete repair of greater than 2 1/2 inch line size accessible anchors... August 31, 1979.
Complete inspection of less thtn 21/2 inch line size accessible anchors... September 30, 1979.
Complete repair of less than 2 1/2 inch line size accessible anchors.. 0ctober 12, 1979.
of presently available This schedule is based on the use personnel and resources. Any significant increase in the failure rate will be brought to the attention of the NRC staff (Mr. Modenos/Mr. Herdt).
Inaccessible anchors will be inspected 357093
Mr. James P. O'Reilly Augus t 10, 1979
~
during the first extended outage which permits access to their locations.
From our initial response to IEB 79-02, the last sentence of our "In these cases, response to Item 3 needs to be revised as follows:
cyclic requirements will be satisfied by tightening the top nuts only af ter verifying that the leveling nut is backed off."
Based on the following data, it is concluded that continued operation of the Brunswick Steam Electric Plant is justified without undue risk to public health and safety.
Analyses performed to date have shown a small f ailure rate.
1.
2.
Most failed anchors are preloaded to equal or greater than calculated load.
A relatively small number of seismic supports employ concrete 3.
expansion anchors. Using the projected failure rate of both units, the total failure rate would involve approximately 2% of the total supports.
4.
No system has a high percentage of failures.
Greater than 90% of all anchors lef t to be tested are accessible.
5.
Very truly yo rs,
/
/
B.'
. Furr Manager Generation Department RMP:CSB:dcj*
Enclosure cc:
Mr. Harold Denton Mr. Norman C. hoseley 9
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ENCLOSURE 1 BSEP Proposed Acceptance Criteria 1.
Thread Engagement:
Anchor Size Min. Engagement 3/8 1/4" 1/2 3/8" 5/8 3/8" 3/4 1/2" 7/8 5/8" 2.
Anchor Installation:
(Depth from sleeve top to plug top)
Anchor Size Plug Depth 3/8 25/32" 1/2 1 5/32" 5/8 1 13/32" 3/4 1 31/32" 7/8 2 9/32"
(+ 1/8")
3570 tit 3