ML20101C606

Provides Supplemental Response to IE Bulletins 79-02,79-07 & 79-14 Re CRD Support Sys,Anchor Bolt Insp & Other Support Sys.Anchor Bolt Insps Completed.Installation of long-term Fixes Continuing

ML20101C606
Person / Time
Site:	Brunswick
Issue date:	11/26/1984
From:	Cutter A CAROLINA POWER & LIGHT CO.
To:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
References
IEB-79-02, IEB-79-07, IEB-79-14, IEB-79-2, IEB-79-7, NLS-84-214, NUDOCS 8412210138
Download: ML20101C606 (4)

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A Carolina Power & Light Company SERIAL:

NLS-84-214 NOV 61984-34 g s

Mr. James P. O'Reilly, Regional Administrator United States Nuclear Regulatory Cotsmission Suite 2900 101 Marietta Street, NW

. Atlanta,.GA'. 30303 BRUNSWICK STEAM ELECTRIC PLANT, UNIT NOS. 1 AND 2 DOCKET NOS. 50-325 & 50-324/ LICENSE NOS. DPR-71 & DPR-62 SUPPLEMENTAL RESPONSE TO IE BULLETINS 79-02, 79-07, AND 79-14

Dear Mr. O'Reilly:

The purpose of thin letter is to provide the status of Brunswick Steam Electric-Plant's (BSEP) compliance with the above-referenced bulletins.

CRD System Supports Our letter dated July 29, 1982 (Serial No. BSEP/82-1654), addressed the status of the control rod drive (CRD) system long-term support fixes. For Brunswick-1, the CRD support fixes have been completed as planned.

For Brunswick-2, the CRD support fixes have been completed except for work on the supports located in the reactor vessel foundation wall windows, which will be provided with a more durable design. The remaining Brunswick-2 fixes are planned for completion during the Reload 6 outage, which is currently scheduled to start in the spring of 1987.

Other System Supports Our letter dated July-26, 1982 (Serial No. BSEP/82-1616), addressed the status of.the IE Bulletin (IEB) effort for systems other than control rod drives.

For seismic reanalysis-and associated long-term support fixes, work was reported complete with the exception of the fixes discussed in Section A on page 2.

Due to outage manpower limitations and a heavy work load of other i

NRC-required modifications (such as TMI, Torus Mark I, IEB 79-01B, and i

Hydrogen Recombiner/Off-Gas Treatment), not all of the previously planned long term support fixes were completed. The current status of supports remaining to be modified is as follows:

Accessible Inaccessible (during power operation)

Unit 1 4

1 Unit.2 8

3 8412210138 841126 PDR ADOCK 05000324 G

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411 Fayettevine Street

• P. O Box 1551

• Raleigh. N. C. 27602 l

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Erk James P. O'Reilly 'The accessible support modifications for both units are currently being worked on and it'is anticipated that.this work will.im completed during the first half of.1985.- The remaining hanger modifications for both units will be incorporated in the Brunswick long-term schedule commensurate with other required regulatory work.

Anchor Bolt Inspections As described in our July 26, 1982 letter, the testing of self-drilling anchors; included application of a torque representing a pull,out load equal to or greater than allowable design load for the. anchor.

Concrete embedment and thread engagement were also measured whenever it was possible to remove the

= bolt / stud from the-anchor. Many supports utilized floor-mounted base plates employing self-drilling anchors with threaded rod studs and grout. Because of moisture conditions during plant operation, several studs were found to be frozen-in the anchors and could not be removed for measurement of depth and thread engagement.

Supports with anchors that were tested but did not meet the test acceptance criteria were conservatively evaluated for the load values generated by the IEB 79-07 reanalysis effort. Repairs were made to base plates found deficient by evaluation and to base plates with studs /bolta broken while attempting removal for_ testing.

As' committed in our February. 25, 1981 letter (Serial No. BSEP/81-0440), the scheduled anchor bolt testing per IEB 79-02 of.the additional supports identified for testing is now complete for both units.

The Brunswick-2 summary and test results were transmitted to you in our July 26, 1982 letter.. This letter transmits the Brunswick-1 results (attached) which are summarized below.

Brunswick Results A total of 150 base plates containing 396 anchors were included in this phase of the test program. More than 80 percent of these supports were on two-inch and smaller lines. The base plates were tested to the extent that was reasonably possible. The primary test verifying adequate preload was i

performed on-88 percent of anchor bolts covering 95 percent of the base plates covered in this phase. The test demonstrated the ability of each anchor bolt to withstand its design load. A failure rate of 1.15 percent was obtained for the preload test. The reasons for not testing all anchors included physical inaccessibility, short length of studs preventing lockouts to be installed, studs broken while attempting removal for measurement, and inability to back off leveling nuts underneath the base plates. The low failure rate and extensiveness of the test program provides a high confidence in the ability of

.the existing anchor bolts to accommodate the required loads.

In addition to the preload testing, tests for proper installation were performed.- 79 percent of the anchor bolts were covered by this testing. A failure rate of 0.64 percent was obtained for inadequate embedment and zero percent for-inproper engagement. The anchor bolts not tested were due to

Mr. James P. O'Reilly.s

= frozen studs, anchor bolts which' failed the preload tests (these were repaired as required), and those not tested for preload as discussed in the preceding paragraph.

In addition, sixteen of these anchor bolts which were not fully tested were subsequently replaced for other reasons, further reducing the number of not fully verified anchors.

An overall failure rate of 1.79 percent was obtained from the test program in this phase.. The extensiveness of testing and the low failure rate provides a high confidence level for the adequacy of the support base plates.

In conclusion, the anchor bolt inspections for Brunswick-1 and Brunswick-2 have been completed.

Not all of the support long-term fixes have been installed as planned; however, these represent only about 2 percent of the total fixes required. We continue to be committed to finish this program commensurate with other required regulatory work in the Brunswick long-term schedule.

Yours ery truly

'/

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A. B. Cutter -

kident Nuclear Engineering & Licensing WRM/ccc (036PPC)

Attachment cc:

Mr. D. O. Myers (NRC-BSEP)

Mr. M. Grotenhuis (NRC)

Mr. R. C. DeYoung NRC Document Control Desk

s-o Anchor Bolt Testing Results Summary (Brunswick-1 1981-83 Program)

Total Number of Base Plates 150 Number of Base Plates Tested 142

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Total. Number of Anchors 396 Number of Anchors Tested for Preload 347 Number of Anchors Failed Preload 4

Preload Test Failure Rate 1.15%

Number of Anchors Not Tested for Preload 49 Number not Tested due to Frozen Leveling Nut 16 Number not Tested for Other Reasons 33 Number of Anchors Tested for Embedment 311 Number Anchors with Inadequate Embedment 2

Embedment Test Failure Rate 0.64%~

Number of Anchors not Tested for Embedment 85 Number not Tested due to Frozen Leveling Nut 16 Number not Tested due to Frozen Stud 31 Number not Tested for Other Reasons 38-

-Number of Anchors Tested for Engagement 311 Number of Anchors Tested for Engagement 0%

0%

Engagement Test Failure Rate Number of Anchors not Tested for Engagement 85 Number not' Tested due to Frozen Leveling Nut 16 Number not Tested due to Frozen Stud 31 Number.not Tested for Other Reasons 38 Total Failure Rate 1.79%