ML20004B615

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Submits Supplemental Response to IE Bulletin 81-01, Surveillance of Mechanical Snubbers. Manual Stroke Tests Sent on 810327.Identification of Snubbers Installed on LPIS Submitted on 810416.Snubber to Be Replaced by 810501
ML20004B615
Person / Time
Site: Millstone Dominion icon.png
Issue date: 04/27/1981
From: Counsil W
NORTHEAST NUCLEAR ENERGY CO.
To: Grier B
NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
References
A01531, A1531, IEB-81-01, IEB-81-1, TAC-08952, TAC-8952, NUDOCS 8105290175
Download: ML20004B615 (3)


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Mr. Boyce H. Grier , Director q Region I 4

Office of Inspection and Enforcement U. S. Nuclear Regulatory Commission gga g 8 631 Park Avenue King of Prussia, PA 19h06

References:

(1) B. H. Grier letter to W. G. Counsil, dated January 27, 1981, transmitting I&E Bulletin No. 81-01.

(2) W. G. Counsil letter to B. H. Grier, dated March 27, 1981.

(3) W. G. Counsil letter to B. H. Grier, dated April 16, 1981.

Gentlemen:

Millstene Nuclear Power Station, Unit No. 2 I&E Bulletin No. 81-01, Mechanical Snubbers In Reference (1), the NRC Staff requested that Northeast Nuclear Energy Company (NNECO) perform certain actions to determine the condition of mechanical snubbers, specifically those manufactured by International Nuclear Safeguards Corporation (INC), at Millstone Unit No. 2.

In Reference (2), NUECO reported the results of the manual stroke tests performed on the accessible INC mechanical snubbers at Millstone Unit No. 2.

It was reported in Reference (2) that of a total of eighty eight (88) INC mechanical snubbers installed on safety-related systems, forty two (h2) were accessible. Of the inaccessible snubbers, forty one (hl) are located within containment and are inaccessible during normal operation. The re-maining five (5) inaccessible snubbers are locat?d outside containment on the Low Pressure Safety Injection (LPSI) system piping.

These five (5) snubbers consist of the following models:

Model Number MSVA-1 1 MSVA-2 1 MSVA-3 1 MSVA-m 2 8105290 M k

The MSVA-1 and MSVA-3 INC mechanical snubbers will be rep 1 reed with comparable Pacific Scientific snubbers. The snubber replacement is currently in progress and will be completed by May 1, 1981.

The remaining three (3) INC mechanical snubbers installed on the LPSI system will be re=oved entirely. Strese analyses which have been performed for this system demonstrate that minor modifications to one structural anchor are required prior to removal of the snubbers. These modifications will be completed by May 1, 1981, at which time the three snubbers will be removed from the system.

It is noted that this system is currently in a cold (room temperature) con-dition and is utilized only as part of the shutdown cooling system and safety injection system. NNECO has performed a thermal stress analysis for this piping system assuming all five snubbers were locked in the cold position.

Based on the results of this analysis , it is NUECO's conclusion that, assuming these five (5) snubbers are inoperable, the integrity of the LPSI system would be maintained.

With the docketing of this information, NNECO has addressed all INC mechanical snubbers installed on safety-related systems outside containment. In Reference (3), NNECO addressed those INC mechanical snubbers installed on safety-related systems located within containment. As documented in Reference (3), NNECO concludes that operation of Millstone Unit No. 2 until the next cold shutdown is acceptable. It remains NNECO's intention to operate Millstone Unit No. 2 until the next cold shutdown at which time the INC mechanical snubbers in-stalled on safety-related systems within containment will be replaced with snubbers of a different design.

We trust you find this information satisfactory.

Very truly yours, NORTHEAST NUCLEAR ENERGY COMPANY l<

W. G. Counsil T/41 Q Senior Vice President

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Then personally appeared before me W. G. Counsil, who being duly sworn, did state that he is Senior Vice President of reortheast Nuclear Energy Company, a Licensee herein, that he is authorized to execute and file the foregoing information in the name and on behalf of the Licensees herein and that the statements contained in said information are true and correct to the best of his knowledge and belief.

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