ML19291C417
| ML19291C417 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 12/10/1979 |
| From: | Counsil W, Willie Lee NORTHEAST NUCLEAR ENERGY CO. |
| To: | Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| References | |
| IEB-79-02, IEB-79-2, NUDOCS 8001240374 | |
| Download: ML19291C417 (3) | |
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December 10, 1979 Docket No. 50-336 Mr. Boyce H. Grier, Director Region 1 Of fice of Inspection and Enforcement U. S. Nuclear Regulatory Commission 631 Park Avenue King of Prussia, PA 19406
References:
(1)
B. H. Grier letter to W. G. Counsil dated March 8,1979, transmitting I&E Bulletin No. 79-02.
(2)
B. H. Grier letter to W. G. Counsil dated June 21, 1979, transmitting I&E Bulletin No. 79-02, Revision 1.
(3)
W. G. Counsil letter to B. H. Grier dated July 6, 1979.
(4)
B. H. Grier letter to W. G. Counsil dated August 20, 1979, transmitting I&E Bulletin No. 79-02, Revision 1, Supplement 1.
(5) Teledyne Englacering Services Report TR-3501-1, Revision 1, submitted to U. S. NRC Region I dated September 7,1979.
(6)
W. G. Counsil letter to B. H. Grier dated September 19, 1979.
(7)
B. H. Grier letter to W. G. Counsil dated November 8,1979, transmitting I&E Bulletin No. 79-02, Revision 2.
Gentlenen:
- 1111 stone Nuclear Power Station, Unit No. 2 Pipe Support Base Plate Design Using Concrete Expansion Anchor Bolts - I&E Bulletin No. 79-02 Reference (1), as supplemented by References (2), (4), and (7), requested that Northeast Nuclear Energy Company (NNECO) provide information regarding pipe support base plate designs using concrete expansion anchor bolts on Category I systems.
Additionally, Reference (7) requested that NNECO provide a schedule that details the completion dates for Items 1, 2, and 4 of Reference (7).
As reported in References (3) and (5), NNECO is a member of the Owners Group who contracted with Tcledyne Engineering Services (TES) to address the generic questions of the subject Bulletin.
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(1)
In response to Question 1 of I&E Bulletin No. 79-02, the base plates utilizing concrete expansion bolts are being analyzed using the TES modeling approach as described in Reference (5).
Shear-tension inter-action is being accounted for as well as minimum edge distance and proper bolt spacing.
(2)
In response to Question 2 of I&E Bulletin No. 79-02, ultimate shear-tension interaction values as listed in Reference (5) are used and appropriate factors of safety applied to determine allowable design loads on the expansion bolts.
(3) In response to Question 3 of I&E Bulletin No. 79-02, Referenc (5) specifically addresses the cyclic load carrying ability of expansion bolts at both high and low frequencies.
No significant decrease in the static load carrying ability was detected for the types of bolts used at Millstone Unit No. 2.
(4)
In response to Question 4(a) of I6E Bulletin No. 79-02, Reference (5) concluded that preload is not required to develop cyclic capacity if the expansion bolts are installed properly.
In response to Question 4(b) of I&E Bulletin No. 79-02, a testing program was initiated since sufficient QC documentation did not exist for the installation of the expansion bolts.
The types of bolts used at Millstone Unit No. 2 were primarily lillti-Kwik bolts with some Wej-Its.
The recent outage to repair feedwater pi' ping crack indications afforded an opportunity to inspect and test the Category I supports and anchor bolts in inaccessible areas. Approximately eighty percent (80%) of the bolts and supports in the inaccessible areas have been tested, and all bolts and supports have been inspected. Of the 2,100 anchor bolts tested in the 9 Category I piping systems in inaccessible areas, 5 anchor bolts failed.
NNECO has determined this failure rate is well within the 95% confidence level required by I&E Bulletin No. 79-02.
NNECO considers the inspections and tests in inaccessible areas complete.
Testing and inspectians of the anchor bolts and supports in accessible areas is 50% complete and scheduled for completion on or about March 1,1980.
(5)
In response to Question 5 of I&E Bulletin No. i9-02, NNECO has reviewed the Seismic Category I and Saf ety-Related systems and determined that no Category I piping supports, utilizing concrete expansion anchor bolts, derive their support from concrete block walls at Millstone Unit No. 2.
There are, however, six (6) supports located on block walls at Millstone Unit No. 2.
The support capability of these walls is presently being evaluated.
(6)
In response to Question 6 of I&E Bulletin No. 79-02, NNECO has made no distinction between base plates and structural steel plates in the 1795 372
evaluation performed pursuant to the criteria of I&E Bulletin No. 79-02.
Structural steel shapes were included in NNECO's evaluation performed in response to Ref erences (1), (2), (4), and (7).
(7)
In response to Item 7 of I&E Bulletin No. 79-02, NNECO is reanalyzing all support structures utilizing concrete expansion anchor bolts.
This analysis is scheduled to be completed on or about April 1,1980.
The response to Questions 1 and 2 of Reference (7) will be completed at that time.
The testing and inspection of the concrete expansion anchor bol ts in the inaccessible areas is complete.
Results of the inspections and tests performed to date ensure the 95% confidence level required by I&E Bulletin No. 79-02 at Millstone Unit No. 2.
The testing and inspection of the concrete expansion anche* bolts located in accessible areas of the plant pursuant to IsE Bulletin No. 79-02 are scheduled for completion on or about March 1,1980.
A final report will be submitted following completion of all inspections, tests, and analyses.
We trust this information satisfacturily dispositions the concerns of Ref erences (1), (2), (4), and (7).
Very truly yours, NORTHEAST NUCLEAR ENERGY COMPANY W. G.Glounsil Vice President
/
By:
W. F. Fee Vice President r
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