ML19257C707
| ML19257C707 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 01/01/1980 |
| From: | Eisenhut D Office of Nuclear Reactor Regulation |
| To: | Counsil W NORTHEAST NUCLEAR ENERGY CO. |
| References | |
| NUDOCS 8001300098 | |
| Download: ML19257C707 (5) | |
Text
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o UNITED STATES g
NUCLEAR REGULATORY COMMISSION y
WASHINGTON, D. C. 20555
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January 1, 1980 Docket No. 50-245 Mr. W. G. Counsil, Vice President Nuclear Engineering and Operations Northeast Nuclear Energy Cogany Post Office Box 270 Hatford, Connecticut 06101
Dear Mr. Counsil:
Recent seismic design evaluations conducted in the Systematic Evaluation Program (SEP) have indicated a potential safety concern relative to the anchorage and support of safety related electrical equipment.
It has also been observed that non-seismic Category I auxiliary items (dolleys, gas bottles, etc.) may be dislodged by an earthquake and damage safety related equipment. These issues were identified during site visits to Dresden 2, Haddam Neck, Ginna, Oyster Creek, Palisades and Millstone 1 by review teams consisting of NRC representatives and consultants. Since operability of the subject equipment may be essential during and af ter a seismic disturbance, we request that you assess the capability of all safety related electrical equipment (as well as non-seismic Category I auxiliary items) to resist seismic forces and iglement remedial measures, as necessary, to increase safety margins. All operating licensees of nuclear power facilities are being notified of this issue by an I&E Information Notice (Enclosure 1).
Within 30 days, you are requested to develop an' action plan for resolution of this issue and to submit it for our review. The following issues should be addressed:
1.
Does positive anchorage exist (load carrying mechanism other than friction);
2.
If positive anchorage exists, has the anchorage system been engineered with adequate capacity; and 3.
Was the anchorage fabricated to quality standards?
The results of your investigation of Item 1 should be submitted within 60 days of the date this letter is received.
It should describe any corrective action considered necessary. The overall issue, including any required modifications, should be resolved by September 1,1980.
IB M 140 p 8 00130 0 0 9 f
2-Although the final seismic design basis for your facility has not been resolved, and other changes may be required, appropriate action on t'.is matter should not be delayed.
If necessary, consideration should be given to providing temporary supports with more permanent supports being installed after all seismic questions have been resolved.
S ncerely, c
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DarreTT G. Et'se'nhu"t, Acting Director Division of Operating Reactors Office of Nuclear Reactor Regulation Enclosu e:
As stated cc w/ enclosure:
See next page J
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. cc w/ enclosure:
William H. Cuddy, Esquire Connecticut Energy Agency Day, Berry & Howard ATTN: Assistant Director Counselors at Law Research and Policy One Constitution Plaza Development Hartford, Connecticut 06103 Department of Planning and Energy Policy Anthony Z. Roisman 20 Grand Street Natural Resources Defense Council Hartford, Connecticut 06106 917 15th Street, N. W.
Washington, D. C.
20005 Director, Technical Assessment Division Northeast Nuclear Energy Company Office of Radiation Programs ATTN:
Superintendent (AW-459)
Millstone Plant U. S. Environmental Protection P. O. Box 128 Agency Waterford, Connecticut 06385 Crystal Mall #2 Arlington, Virginia 20460 Mr. James R. Hinmelwright Northeast Utilities Service Company U. S. Environmental Protection P. O. Box 270 Agency Hartford, Connecticut 06101 Region I Office ATTN:
EIS COORDINATOR Nuclear Regulatory Commission, Region I JFK Federal Building Office of Inspection and Enforcement Boston, Massachusetts 02203 ATTN: John T. Shedlosky 631 Park Avenue King of Prussia, Pennsylvania 19406 Waterford Public Library Rope Ferry Road, Route 156 Waterford, Connecticut 06385 First Selectman of the Town of Waterfort Hall of Records 200 Boston Post Road Waterford, Connecticut 06385 1835 142'
UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT WASHINbTON, D.C.
20555 NOVEMBER
,1979 IE Information Notice No. 79-ANCHORAGE AND SUPPORT OF SAFETY RELATED ELECTRICAL EQUIPMENT Description of Circumstances Recent seismic design evaluations in connection with the NRC Systematic Evaluation Program (SEP) have indicated a potential safety deficiency relative to the anchorage and support of safety related electrical equip-ment. This subject whs highlighted for mor, in-depth evaluation af ter site visits to several facilities. These reviews have inoicated that equipment is supported in a non-uniform manner.
This may have resulted from the fact that ear'ier engineering design criteria did not require rigorous analyses.
Further tvaluations are continuing for tne SEP plant designs.
In some cases, design mcitifications may be required to render acceptable seismic design ma rgi ns.
In general a lack of engineered supports of safety related electrical equip-ment has b en observeo at certain SEP plants. Typical components affected incluae:
-AC and DC motor control centers
-transformers
-switc~ gear
-inverters
-contrei room panels
-battery racks
-instrument panels
-cable trays Also, a rel sted cbservation indicates that non-seismic Category I ancillary items (coll eys, gas bottles, block and tackle gear, ductwork, etc.) are located su:h tnat they may dislodge, i@act ano damage safety related equipment turing an earthquake.
The types of anchorage systems utilized in these plants and their expected capacities sary widely. For exagle, high uncertainty exists relative to the capacity of non-engineered tack welds and attachments that rely on frictional claging forces.
In some cases, equipment has been found free standing with no means of positive lateral support.
(Friction being the only lateral load carryng mechanism). Most of ten, heavier equipment is anchored using 1) tack welds to steel angles emoended in concrete; 2) clips that rely on frictional resistance; 3) concrete embedded anchor Dolts; or
- 4) external braced frames. Lighter equipment housed in cabinets or attached to panels or racks has been anchored using 1) bolts; 2) sheet metal screws; 3) tack welds; and 4) braced racks.
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2-The potential concern is that certain pieces of equipment may not have adequate levels of seismic resistance capability due to limited anchorage capacity. The potential problems relate to overturning and/or sliding of large equipment and gross movement or unacceptable forces on smaller attached equipment that may render it inoperable during an earthquake.
For certain large battery racks, this judgement is supported by computations that predict unacceptable seismic behavior.
Section 3.10 of the Standard Review Plan provides acceptance criteria for the seismic qualification of Category I electrical equipment. These criteria include IEEE Std. 344, " Guide for Seismic Qualification of Class 1 Electrical Equipment for Nuclear Power Generating Stations", first issued in 1971.
Facili-ties designed tefore about 1971 without benefit of such design and testing criteria may have some anchorage def teiencies.
The NRC staff is continuing to evaluate this issue on the SEP plants as part of the seismic review in the SEP. Remedial action has been taken on one SEP plant to date.
This Information Notice is pruided as an early notification of a possible significant matter.
It is expected that recipients will review the design criteria for anchorage and support of safety related electrical equipment including as-built installation details to assure adequate capability to resist seismic forces. No written response is required.
If you have any questions regarding this matter, please contact the Director of the appropriate NRC Regional Office.
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