ML19309H580
| ML19309H580 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 04/07/1980 |
| From: | Counsil W NORTHEAST NUCLEAR ENERGY CO. |
| To: | Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| References | |
| IEB-79-02, IEB-79-2, NUDOCS 8005130530 | |
| Download: ML19309H580 (3) | |
Text
f:b 000513053o NORTHEAST UTILITIES
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aa oNNECTICUT 06101 L
t TJ r,=O7.274.VO April 7, 1980 Docket No. 50-2h5 Mr. Boyce H. Grier, Director Region I Office of Inspection and Enforcement U. S. Nuclear Regulatory Co= mission 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)
W. G. Counsil letter to B. H. Grier dated June 8,1979 (3)
B. H. Grier letter to W. G. Counsil dated June 21, 1979, transmitting I&E Bulletin No. 79-02, Revision 1.
(4)
W. G. Counsil letter to B. H. Grier dated July 6,1979 (5)
B. H. Grier letter to W. G. Counsil dated August 20, 1979, transmitting I&E Bulletin No. 79-02, Revision 1, Supplement 1.
(6) Teledyne Engineering Services Report TR-3501-1, Revision 1, submitted to U. S. NRC Region I, dated September 7, 1979 (7)
W. G. Counsil letter to B. H. Grier dated September 19, 1979 (8)
B. H. Grier letter to W. G. Counsil dated November 8, 1979, transmitting I&E Bulletin No. 79-02, Revision 2.
(9)
W. G. Counsil letter to B. H. Grier dated December 7,1979 (10)
B. H. Grier letter to J. F. Opeka dated January 14, 1980.
(11)
W. G. Counsil letter to B. H. Grier dated February 1,1980.
Gentlemen:
Millstone Nuclear Power Station, Unit No. 1 Pipe Support Base Plate Design Using Ccncrete Expansion Anchcr Bolts - ILE Bulletin No. 79-02 Reference (1), as supplemented by References (3), (5), and (8), 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 (8) requested NNECO provide a schedule that details the completion dates for items 1, 2, and 4 of Reference (8).
NNECO is pleased to report the analysis of Category I pipe supports utilizing concrete expansion bolts is complete, with the exception of the eight containment penetration anchors.
. Support modifications are nearing completion to bring factors of safety on all systems except the containment penetrations which are discussed below to four (4) for vedge and five (5) for shell-type expansion bolts.
Reference (h) stated the load carrying shell-type expansion bolts on the shutdown cooling system were replaced with new vedge-type bolts. Further inspections have shown that seven additional supports with shells were not replaced, bovever, these supports have since been analyzed, consistent with References (6) and (9) and tested in accordance with plant procedures for tension testing shell-type expansion bolts.
Containment Penetration Anchors As stated in Reference (11), the containment penetration anchors were initially identified as having cast in place anchor bolts.
In January, 1980, while modifying the isolation condenser penetration anchor X-10A, the bolts used were found to be both cast in place bolts and grouted in place Williams' Rock Bolts, a wedge-type espansion bolt.
The 79-02 procedures were revised to include testing of tLese bolt 3.
The Williams' Rock Bolts at the accessible penetrations were then inspected a ad tested; no failures occurred. The remaining penetration i
bolts are being scheeuled for testing during the 1980 refueling outage.
Teledyne Engineering Services has performed tests of the load carrying capacity of Williams' Rock Bolts grouted in place, which confirm the manufacturer's stated ultimate cepacity.
Ebasco Services, Incorporated, has been contracted to reanalyze the containment penetration anchors considering High Energy Pipe Break (HEPB). Resultant pipe loads are presently being generated, after which a structural analysis of the supporting frames vill be done. Reactions at the support points will be applied to base plates to determine the loads in the Williams' Rock Bolts.
The base plate and bolt analysis vill be done consistent with the analytical approach as described in References (6) and (9). This work is currently scheduled to be completed on or about February 1, 1981.
Ebasco and N7i2C0 vill also establish the compatibility of ASME Level D service limits as required by ASME,Section III, with the appropriate design procedure during faulted conditions (HEPB) combined with normal loads.
I Since HEPB is not specifically included in the scope of I&E Bulletin No. 79-02, the following criteria for expansion bolts has been established by UNECO for Level D Service Limits: ASME Section III, Division 1, Appendix F, Procedure F-1370, which establishes design procedures for component supports.
Procedure
F-1370 permits higher allowable stresses for supporting structural components.
The same concept applied to expansion bolts results in a factor of safety of two between ultimate capacity and design load.
We trust this information satisfactorily dispositions the concerns of the NRC.
Very truly yours, NORTHEAST NUCLEAR ENERGY COMPANY J.
W.'G. Counsil Vice President i
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