ML19211D318
| ML19211D318 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 01/01/1980 |
| From: | Eisenhut D Office of Nuclear Reactor Regulation |
| To: | Peoples D COMMONWEALTH EDISON CO. |
| References | |
| NUDOCS 8001170514 | |
| Download: ML19211D318 (2) | |
Text
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NUCLEAR REGULATORY COMMISSION g
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WASHINGTON, D. C. 20555 k+.v /
January 1, 1980 Docket No. 50-10 Mr. D. Louis Peoples Director of Nuclear Licensing Connonwealth Edison Company Post Office Box 767 Chicago, Illinois 60690
Dear Mr. Peoples:
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. /hese 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 after 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 inplement 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 fr.iction);
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 I 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.
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Although the final seismic design basis for your facility has not been resolved, and other changes may be required, appropriate action on this 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'i ncerely,
(*
0)R'l ffcbIlJ arrell{G. Erdennut,llA ting Director Division of Operating Reactors Office of Nuclear Reactor Regulation
Enclosure:
As stated cc w/ enclosure:
See next page 1763 217
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. cc w/ enclosure:
Isham, Lincoln & Beale Director, Technical Assessment Counselors at Law Division One First National Plaza, 42nd Floor Office of Radiation Programs Chicago, Illinois 60603 (AW-459)
U. S. Environmental Protection
,Mr. B. B. Stephenson Agency Plant Superintendent Crystal Mall #2 Dresden Nuclear Power Station Arlington, Virginia 20460 Rural' Route #1 Morris, Illinois 60450 U. S. Environmental Protection Agency V. S. Nuclear Regulatory Commission Federal Activities Branch ATTN: Jimmy L. Barker Region V Office P. O. Box 706 ATTN:
EIS COORDINATOR Morris, Illinois 60450 230 South Dearborn Street Chicago, Illinois 60604 Susan N. Sekuler Assistant Attorney General Environmental Control Division 188.W. Randol ph Street Suite 2315 Chicago, Illinois 60601 Morris Public Library 604 Liberty Street Morris, Illinois 60451 Chairman Board of Supervisors of Grundy County Grundy County Courthouse Morris, Illinois 60450 Department of Public Health ATTN: Chief, Division of Nuclear Safety 535 West Jefferson Springfield, Illinois 62761 d
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UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT WASHIN(2 TON, 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 ano support of safety related electrical equip-ment. This subject was highlighted for more in-cepth 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 earlier engineering design criteria did not require rigorous analyses.
Further evaluations are continuing for tne SEP plant designs. In some cases, design mooifications 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 been observeo at certain SEP plants. Typical components affected include:
-AC and DC motor control centers
-transformers
-switch gear
-inverters
-control room panels
-battery racks
-instrument panels
-cable trays Also, a related observation indicates that non-seismic Category I ancillary items (colleys, gas bottles, block and tackle gear, ductwork, etc. ) are located such tnat they may dislodge, impact ano damage safety related equipment during an earthquake.
The types of anchorage systems utilized in these plants and their expected capacities vary widely. For example, high uncertainty exists relative to the capacity of non-engineered tack welds and attachments that rely on frictional clamping 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 embeaded in concrete; 2) clips that rely on frictional resistance; 3) concrete embedded anchor :;olts; 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 welos; and 4) braced racks.
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. 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 behavi or.
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 before about 1971 without benefit of such design and testing criteria may have some anchorage deficiencies.
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 en one SEP plant to date.
This Information Notice is provided as an early notification of a possible significant matter.
It is expected that recipients will revTew 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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