B11936, Forwards Status Rept Re Implementation of Seismic Interaction Program.Tasks Include:Anchorage Adequacy for Nonseismic Equipment in Seismic Category I Bldgs & Structural Integrity of Piping,Per Sser 4 (NUREG-1031)

Forwards Status Rept Re Implementation of Seismic Interaction Program.Tasks Include:Anchorage Adequacy for Nonseismic Equipment in Seismic Category I Bldgs & Structural Integrity of Piping,Per Sser 4 (NUREG-1031)

ML20151N941
Person / Time
Site:	Millstone
Issue date:	12/20/1985
From:	Opeka J NORTHEAST NUCLEAR ENERGY CO., NORTHEAST UTILITIES
To:	Noonan V Office of Nuclear Reactor Regulation
References
RTR-NUREG-1031 B11936, NUDOCS 8601030242
Download: ML20151N941 (5)

Text

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.u os c e me c-~ HARTFORD, CONNECTICUT 06141-0270 L L J ZTl,O,%%'fg- (203) 665-5000 December 20, 1985 Docket No. 50-423 B11936 Director of Nuclear Reactor Regulation Mr. V. Noonan, Director PWR Project Directorate #5 Division of PWR Licensing - A U.S. Nuclear Regulatory Commission Washington, D.C. 20555

References:

(1) 3. F. Opeka letter to B. 3 Youngblood, Seismic Interaction Program, dated October 31, 1985.

(2) B. 3. Youngblood letter to 3. F. Opeka, Supplement No. 4 to NUREG-1031 - Millstone Nuclear Power Station, Unit 3, dated December 6,1985.

Dear Mr. Noonan:

Millstone Nuclear Power Station, Unit No. 3 Status of Seismic Interaction Program In Reference (1), Northeast Nuclear Energy Company (NNECO) provided the Staff information regarding the seismic interaction program for Millstone Unit No. 3. The seismic interaction program consists of three distinct tasks:

o Demonstrate the adequacy of equipment anchorages for non-seismic equipment in seismic Category I buildings.

o Demonstrate the structural integrity of piping and supports for selected subsystems.

o Perform walkdown to identify swing / sway interactions between non-seismic Category I piping and equipment and Seismic Category I piping and equipment.

In Reference (2), the Staff concluded that the Millstone Unit No. 3 seismic interaction program met the relevant requirements of GDC-1 and 2 and 10CFR100 Appendix A and was acceptaale. However, the Staff included a license condition which requires NNECO to complete the implementation of the seismic interaction program including corrective actions before the unit exceeds 5% power. In a recent telephone conversation, the Staff requested NNECO to provide the status of the implementation of the seismic interaction program for Millstone Unit No. 3. Attachment I provides the status report. A draf t of the final report should be available for NRC Staff review by January 6,1986.

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If there are any questions, please contact our licensing representative directly.

Very truly yours, NORTHEAST NUCLEAR ENERGY COMPANY et. al.

BY NORTHEAST NUCLEAR ENERGY COMPANY Their Agent

, 3. F. Opekad

% F- G A U Senior Vice President STATE OF CONNECTICUT )

) ss. Berlin COUNTY OF HARTFORD )

Then personally appeared before me 3. F. Opeka, who being duly sworn, did state that he is Senior Vice President of Northeast 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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Status Report Millstone Unit No. 3 Seismic Interaction Program The Millstone Unit No. 3 Seismic Interaction Program is discussed in detail in Reference 1. The three major program tasks are:

1. Demonstrate the adequacy of anchorages for non-seismic equipment in seismic Category I buildings.

2. Demonstrate the structural integrity of piping and supports for selected subsystems.

3. Perform walkdowns to identify swing / sway interaction between non-seismic piping and equipment and seismic Category I piping and equipment.

The following is a report on the status of each of these tasks.

1. Demonstration of adequate equipment anchorage has been completed.

Area walkdowns concentrating on equipment anchorage, have concluded that the only equipment with appreciable mass which could cause damaging interaction during an earthquake are:

i) Electrical junction and pull boxes li) Instrumentation stands lii) Emergency lighting / battery boxes iv) Unit heaters v) Motor Control Centers (MCC) vi) MAPP gas piping and stands Large, non-seismic, in-line piping equipment is well supported for operational loads and well separated from seismic Category I equipment.

Thus it is not a seismic interaction threat.

A review of existing calculations (References 2, 3 and 4) and the nature of l the equipment types i) through vi) concludes the following:

i) Non-seismic junction and pull boxes are mounted in exactly the same manner as seismic boxes.

ii) Non-seismic instrumentation stands are identical in design to seismic stands (Reference 4).

iii) All lighting fixtures in seismic Category I buildings are supported seismically. Battery boxes for emergency lighting are secured to their mounts by steel straps. In order to assure no slippage of the batteries within the strap, they have been modified and mechanically fastened to the sheet metal strap.

iv) All unit heaters in seismic Category I buildings with the exception of those in the Main Steam Valve Building (MSVB),

have been supported seismically. A walkdown of the MSVB revealed two unit heaters which could have damaging interactions with adjacent seismic Category 1 instrument racks.

A modification has been issued to seismically support these two heaters.

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v) All MCCs in seismic Category I buildings are supported seismically (Reference 3).

vi) Several cases of loosely supported MAPP gas piping and stands were observed during walkdowns. Since this piping is not required beyond construction, it is being removed.

Considering the implementation of the above-mentioned modifications, the adequacy of non-seismic equipment anchorages in seismic Category I buildings has been adequately addressed.

2. The structural integrity of non-seismic piping and supports is being addressed through a pro,' ram conducted by Sargent and Lundy. Bounding piping subsystems have baen selected and are being analyzed in accordance with the criteria established in Reference 1. Following is a detailed summary of the Sargent and Lundy effort.

Twenty-seven piping subsystems were selected and were field verified by walkdown. Preliminary piping analyses of 22 subsystems have been completed to date. The results presented below are preliminary and require some further verifications.

The piping stress analysis indicates generally low stress levels in the piping with most locations being within the ASME Code stress allowables utilized in this program and documented in Reference 1. A few locations with high stress indices have stresses exceeding allowables. All analyses performed so far are based on the response spectrum method utilizing Code Case N-411 and the 1983 Code with summer 1985 Addenda. Additional analyses using SSE building acceleration time history is being performed to reduce conservatisms in calculated stresses at locations exceeding allowables.

Piping deflections are generally small and are within the 6" envelope being used for the interaction walkdown. A few subsystems indicate deflections exceeding the 6" value. It is suspected that the larger deflection is due to the conservatism in the response spectra analysis. SSE acceleration time history analysis is being performed on subsystems with the larger deflections to reduce conservatism in calculated seismic movements.

Piping support evaluations have started. In general, pipe support loads -

have increased by a factor of two times ever normal design loads with a few support loads increasing beyond that. The allowable support loads generally increase by a factor of two in going from Service Level A to D allowables and therefore, most supports should be acceptable. All supports, including those with load increases greater than two times, are being evaluated; however, only a few supports have been reviewed so for and no firm conclusions can be drawn at this time. Supports reviewed so far indicate sufficient capacity to meet the load demand. Additional time history analysis will be performed to reduce conservatisms in calculated SSE loads, if needed.

3. Interactions between non-seismic piping and equipment and seismic Category I piping and equipment are being identified by walkdowns.

Equipment walkdowns were discussed in task I. Piping walkdowns consist of two phases. Due to the cuncerns regarding higher damage potential, large bore piping (25" and larger) are being walked down line by line. Area walkdowns are being conducted to identify small bore interactions. As of December 16, 1985 2,353 piping interactions have been identified. 247 of these piping interactions require modifications and 120 modifications have been installed. All walkdowns and modifications in containment have been completed. All large bore walkdowns are scheduled to be completed by December 20, 1985 with area walkdowns to be completed by December 31, 1985.

References

1. Letter from 3. F. Opeka to B. 3. Youngblood, dated October 31,1985, with attachment.

2. Stone & Webster Calculations: 12179-NM(B)-399,406 and 397.

3. " Determination of Anchorage Loads from M'otor-Control Centers," 12179-NM(S)-688-CZC-0.

4. " Seismic Qualification of Generic Instrumentation Stands," 12179-NM(B)-

505-CZC-0.

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