05000255/LER-1992-028, :on 920331,potential Inability to Maintain Diesel Generator Room Temp Qualification Due to non-1E Qualified Cooling Fan Noted.Procedures Revised & Design Will Be Corrected

:on 920331,potential Inability to Maintain Diesel Generator Room Temp Qualification Due to non-1E Qualified Cooling Fan Noted.Procedures Revised & Design Will Be Corrected

ML18058B850
Person / Time
Site:	Palisades
Issue date:	05/21/1993
From:	Roberts W, Slade G CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.)
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-92-028, LER-92-28, NUDOCS 9306020166
Download: ML18058B850 (6)

LER-1992-028, on 920331,potential Inability to Maintain Diesel Generator Room Temp Qualification Due to non-1E Qualified Cooling Fan Noted.Procedures Revised & Design Will Be Corrected

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(ii)
2551992028R00 - NRC Website

text

consumers Power POW ERi Nii NllCHlliAN'S PROliRESS Palisades Nuclear Plant:

27780 Blue Star Memorial Highway, Covert, Ml 49043 May 21, 1993 Nuclear Regulatory Commission Document Control Desk Washington, DC 20555 GB Slade General Manager c _/

i DOCKET 50-255 - LICENSE DPR PALISADES PLANT - LICENSEE EVENT REPORT 92-028 POTENTIAL INABILITY TO MAINTAIN DIESEL GENERATOR ROOM TEMPERATURE QUALIFICATION DUE TO NON IE QUALIFIED COOLING FAN - SUPPLEMENTAL REPORT Licensee Event Report {LER) 92-028-03 is attached. This supplement~l report revises one of the corrective actions stated in the LER.

Analysis of the cooling capabilities of the diesel generator room fans showed that the peak temperature of the room could reach 1I0°F versus the FSAR stated design maximum of 104°F.

One of our corrective actions was to improve the temperature qualification of the necessary equipment in the room to assure it could meet the ll0°F peak temperature.

Our proposed corrective action indicated we would improve the equipment temperature qualification to approximately 115°F.

The attached LER corrective action section has been revised to show that the actual peak temperature limit the equipment was qualified to was ll0°F. This event was reported in accordance with 10 CFR 50.73{a){2){ii) as a condition outside the design basis of the plant.

~,-L ~~

Gerald B Sl~"""'

General Manager CC Administrator, Region III, USNRC NRC Resident Inspector - Palisades*

Attachment

~80034 9306020166 930521 PDR ADOCK 05000255 S

PDR A CMS' ENERGY COMPANY

NRC Form 366 U.S. NUCLEAA REGULATORY COMMISSION 19*831 APPROVED OMB NO. 3160-0104 EXPIRES: 8/31 /86 LICENSEE EVENT REPORT (LERI FACILITY NAME 11 I DOCKET NUMBER 121 PAGE 131 Palisades Plant ojs!ojolol2ls!s 1 I OF 01 5 TITLE 141 POTENTI'AL INABILITY TO MAINTAIN DIESEL GENERATOR ROOM TEMPERATURE QUALIFICATION DUE TO NON lE OUAL TFIF.D r.nm,TN~ li'.N EVENT DA TE 16)

LEA NUMBER 161 REPORT DATE 161 OTHER FACILITIES INVOLVED 181 SEQUENTIAL REVISION FACILITY NAMES MONTH DAY YEAR YEAR NUMBER NUMBER MONTH DAY YEAR N/A 0161010101 I ol 3 31 1 9 2

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I 3 ol 'l 21 1 91 3 N/A 0161010101 I THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR I: !Ch<<:lt one ormon of 1M following) 111)

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MODE 191 20.4021bl 20.4061cl 60.731*11211iv) 73.71(b)

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60. 731*ll2llviiil1Bl NRC Form 388Al 20.4061*111 IM 60.731*ll2lliiil 60.731*11211xl LICENSEE CONTACT FOR THIS LER (12)

NAME TaEPHONE NUMBER William L. Roberts, Staff Licensing Engineer 6ARIEA1CI°~ I 7 I 6 I 4 I -lalsl113 COMP\\.ETE ONE LINE FOR EACH COMPONENT F~LURE DESCRIBED IN THIS REPORT 1131 MANUFAC*

REPORTABLE MANUFAC*

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~NO SUBMISSION I I I DATE 1161 ABSTRACT IUmit ID 1400_... ;:... _;,,,.re1y rfftffn ~-*

fY/MWmrM W..*l IHll On March 31, 1992, at approximately 1100 hours0.0127 days <br />0.306 hours <br />0.00182 weeks <br />4.1855e-4 months <br />, the plant was in cold shutdown preparing to start up from a refueling outage.

Results of analysis of the emergency diesel generator rooms cooling requirements and installed safety related cooling capability revealed that the existing cooling capability was not adequate to maintain the room teq:>erature within the required design t~ratures.

Analysis results indicate that the existing configuration of having only 1 of the 2 emergency diesel generator room cooling fans powered from a class 1E source is not adequate to maintain the emergency diesel generator room t~rature below the design limit of 104°F, with a design outdoor teq:>erature of 95°F.

The analysis results also showed that with one cooling fan in operation, the room t~rature could be maintained below the design limit only if the outdoor t~rature does not exceed 75°F.

Procedures have been revised to al low for re-energ1zing the non-safety related electrical bus that powers the second fan when the outdoor teq:>erature exceeds 75°F.

This condition was caused by an original design and construction error. The rooms were designed to be cooled by 2 safety related fans however, only one fan in each room is powered from a safety related power source.

During conceptual engineering for powering the second cooling* fan in each diesel generator room from class 1E sources, it was determined that the existing power supply cables for all four fans are located in a single fire area, and do not meet the Appendix "R" criteria for cable separation.

Technical Specifications required hourly fire tours were initiated and will continue until the design is corrected.

NRC Form 388A 19-831 FACILITY NAME 111 Palisades Plant

EVENT DESCRIPTION

LICENSEE EVENT REPORT (LERI TEXT CONTINUATION DOCKET NUMBER 121 LER NUMBER 131 U.S. NUCLEAR REGULATORY COMMISSION APPROVED OMB NO. 3160-010*

EXPIRES: 8/31186 PAGE 141 SEQUENTIAL REVISION YEAR NUMBER NUMBER o I s I o I o I o I 2 I s I s s I 2

- o I 2 I s - o 13 o I 2 oF o Is On March 31, I992, at approximately 1100 hours0.0127 days <br />0.306 hours <br />0.00182 weeks <br />4.1855e-4 months <br />, the plant was in cold shutdown preparing to start up from a refueling outage. Results of analysis of the emergency diesel generator rooms cooling requirements and installed safety related cooling capability revealed that the existing cooling capability was not adequate to maintain the room temperature within the required design temperatures. Analysis results indicate that the existing configuration of having only I of the 2 emergency diesel generator room cooling fans [EK;FAN] powered from a class IE source is not adequate to maintain the emergency diesel generator room temperature below the design limit of I04°F, with a design outdoor temperature of 95°F.

The analysis results also showed that with one cooling fan in operation, the room temperature could be maintained below the design limit only if the outdoor temperature does not exceed 75°F.

To permit plant operation at outside temperatures greater than 75°F, actions were taken such that power would be supplied to the second fan in each room when needed.

System Operating Procedure (SOP) 22, "Emergency Diesel-Generators", was revised to require that the electrical bus that powers the non-safety room cooling fan be re-powered from the emergency diesel generator needing the cooling, within 30 to 40 minutes after the generator is started, if the outside air temperature is greater then 75°F.

This action is deemed as an interim action until a permanent class IE power source can be supplied to the second room cooling fan.

The analysis also showed that under existing plant conditions, the two cooling fans would only be able to cool the room to a temperature of II0°F verses the I04°F design temperature.

The temperature rating of the limiting equipment in the rooms will be revised to allow operation of the equipment in a higher temperature environment.

During conceptual engineering of the modification for powering the second cooling fan in each diesel generator room from class IE sources, it was determined that the existing power cables for all four fans are all located in a single fire area (cable spreading room) and do not meet the Appendix "R" criteria for cable separation. Technical Specification required fire tours were initiated in the cable spreading room.

Further reviews found indications that some of the diesel fan cables also followed a parallel route through the plant and fire tours were initiated in these routing ~reas as well. This discovery was reported to the NRC on May 20, I992, as a condition outside of the plant design basis.

This event is reportable in accordance with IO CFR 50.73(a)(2)(ii) as a condition outside of the design basis of the plant.

CAUSE OF THE EVENT

The root cause of the event was the inadequate implementation of the original emergency diesel generator room cooling design.

The original design fan sizing calculations show that the original design intent was to have both of the room fans in operation to maintain the diesel generators operable.

NRC Form JeeA l&-831 U.S. NUCLEAR REGULATORY COMMISSION APPROVED OMB NO. 3i60-010*

EXPIRES: 8/31 /86 LICENSEE EVENT REPORT (LERI TEXT CONTINUATION FACILITY NAME 111 DOCKET.NUMBER 121 lER NUMBER 131 PAGE 141 SEQUENTIAL REVISION YEAR NUMBER NUMBER Palisades Plant 0 I 5 I 0 I 0 I 0 I 2 I 5 I 5 9 I 2 0 12 1a -

0 13 0 r OF 0 1s This event did not involve the failure of any equipment important to safety. When it was determined that the fans were needed to support diesel generator operability, the Appendix "R" cable separation implications were not immediately recognized, and was a cognitive personnel error.

ANALYSIS OF THE EVENT

In 1991 as part of the on-going Palisades Configuration Control Project a number of apparent discrepancies in circuit routing were identified. The power and control circuits, for one of the safety related emergency diesel generator cooling fans, were two of the circuits determined to be mis-routed.

Because of these two circuit deficiencies a special Plant Review Committee (PRC) meeting (91-030) was convened to address the operability of the associated emergency diesel generator (1-1). The committee found that actions were needed to provide alternate room cooling for the (1-1) diesel generator. These actions were established and remained in place until the fans cables could be rerouted to resolve the deficiency. The fan cables were rerouted on October 19, 1992.

Prior to this time, as part of an Appendix R safe shutdown analysis, an analysis had been completed to assess the ability to cool the diesel generator room by natural convection rather than by forced convection. This analysis concluded that opening the doors and blocking open the ventilation louvers would provide adequate cooling to maintain the diesel generator operable.

As a follow-up and as part of the corrective actions for the identified cable routing discrepancies, an evaluation for the operability requirements for the diesel generator ventilation was assigned~

As a result, the System Engineering Department performed a preliminary analysis which concluded that natural circulation may not be sufficient to cool an operating diesel generator, and when outside temperatures reach near the design limit, two room cooling fans may be needed.

This issue was addressed at the regular PRC (92-038) meeting in October of 1991.

The PRC concluded that based on a Plant Safety Engineering analysis that the diesel generators were operable, but that an unreviewed safety question may exist in that we were outside the design basis of the plant. At this time we did not have the knowledge that the original design had called for b9th room cooling fans to cool the room under maximum design conditions. This was discovered when we requested the plant architect engineer to complete a formal room HVAC analysis. Therefore, we believed that the original design was as the plant was configured, that is with one room cooling fan powered from a IE power source.

As a follow-up to the PRC meeting the operability of the emergency diesel generator was discussed with the Palisades Senior Resident Inspector and the Region III Reactor Projects Section Chief for Palisades. It was agreed that there was no immediate operability concern and a license amendment need not be pursued unless we proposed to permanently accept the condition.

The plant architectural engineer was asked to perform a formal analysis of the emergency diesel generator room cooling requirements.

The results of their analysis showed that both room cooling fans would be required to maintain the required room cooling above an outdoor 19-831 FACILITY NAME 11)

Palisades Plant LICENSEE EVENT REPORT (LERI TEXT CONTINUATION DOCKET NUMBER 121 LER NUMBER 131 U.S. NUCLEAR REGULATORY COMMISSION APPROVED OMB NO. 3160-0104 EXPIRES: B/31/86 PAGE 14)

SEQUENTIAL REVISION YEAR NUMBER NUMBER 0

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5 temperature of 75°F and that design limit of I04°F cannot be maintained with an outdoor temperature above approximately 88°F, even with both fans operating. Diesel generator operability will be assured for outdoor temperatures above 75°F by procedural controls which require the operators to re-energizing the bus which feeds the non-IE powered fans.

This procedural re-powering action will be in place until a modification can be completed to power the fans from a IE source.

In addition, by the time the outdoor temperature exceeds 88°F, it is our intent to assure that the diesel *generator can operate in an environment six degrees higher than was originally called for in the Palisades design.

We are examining the vendor ambient temperature limitations for critical operational components on the emergency diesel generators and have found that NEMA rated components are the limiting components.

The NEMA standards provide for temperature rating of components at an ambient temperature of I04~F. The staridard also provides guidelines for operation o components at higher ambient temperatures. We believe that based on the small temperature difference between the rooms original design rating and that which is now calculated (6°F),

that we will have no problem adjusting the rating of the necessary components to meet the 110°F limit.

When the results of the plant architectural engineer analysis of the emergency diesel generator room cooling was received, it was not inunediately realized that the Appendix "R" cable separation criteria may also need to be reviewed.

The calculation (EA-A-PAL-86-0I, Rev. 2} that originally showed the diesel generators could be cooled without the installed fans, discussed Appendix "R" room cooling requirements, but not fan cable separation.

The Appendix "R" cable separation deficiencies were uncovered as part of the conceptual engineering phase of the modification to provide class IE power to the second cooling fan in each diesel generator room.

The plant modification process requires that Appendix "R" design criteria be evaluated for every plant modification.

All four existing power cables for the cooling fans, two per generator, are located in the cable spreading room which is a single fire area. Technical Specification required hourly fire tours are in place to compensate for these design deficiencies. Since some of the cooling fan power cables follow parallel routes from the C40 panel and cable spreading roo to the diesel generator rooms, fire tours are also in place in the fire zones that these cables are routed.

The fire tours will remain in place until modifications are completed to 'resolve these deficiencies.

CORRECTIVE ACTION

Activities to improve temperature qualification of necessary equipment in the emergency diesel generator rooms to ~pproximately IIS°F will be completed by June 30, I992.

~-.

• 19*831 FACILITY NAME 111 Palisades Plant LICENSEE EVENT REPORT (LERI TEXT CONTINUATION OOCi<;ET NUMBER 121 YEAR LER NUMBER 131 SEQUENTIAL NUMBER U.S. NUCLEAR REGULATORY COMMISSION APPROVED OMB NO. 3160-0104 EXPIRES: 8/31 /86 REVISION NUMBER PAGE 141 o I s I o I o I o I 2 I s I s s I 2 o I 2 I s -

o I 3 o I s oF o I s Our letter, dated May 29, 1992, revised the completion date of the equipment temperature qualification upgrade from June 1, 1992 until June 30, 1992.

The results of the temperature qualification improvement efforts raised the temperature qualification of the necessary equipment in the emergency diesel generator rooms to ll0°F.

The raising of the qualification to ll0°F is consistent with the design capabilities of the diesel generator room cooling fans.

A modification will be implemented which will power all emergency diesel generator room ventilation fans from class IE power sources and comply with Appendix "R" cable separation criteria. Hourly fire tours will continue until the modification is completed.

(Status of our progress in completing these modifications was sent to the NRC in a letter dated March 23, 1993.)

ADDITIONAL INFORMATION

Recently submitted licensee event reports which also dealt with the subject of operability of the emergency diesel generator room cooling fans was LER 91-014.

This emergency diesel generator room cooling condition is an open item in NRC Inspection Report 91-019, Item 23.