ML20196K362

Rev 0 to Final Technical Evaluation of Three Mile Island Unit 1 Fire Barrier Ampacity Derating Assessments & RAI Responses

ML20196K362
Person / Time
Site:	Three Mile Island
Issue date:	01/06/1998
From:	Nowlen S SANDIA NATIONAL LABORATORIES
To:	Ronaldo Jenkins NRC (Affiliation Not Assigned)
Shared Package
ML20196K354	List: ML20196K351 ML20196K356 ML20196K362
References
CON-FIN-J-2503 NUDOCS 9901260483
Download: ML20196K362 (8)

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A Final Technical Evaluation of the Three Mile Island Unit 1 ,

Fire Barder Ampacity Derating Assessments and RAI Responses '

A LetterReport to the USNRC l

Revision 0 '

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1 January 6,1998 Prepared by:  !

SteveNowlen '

SandiaNationalLaboratories  !

Albuquerque, New Mexico 87185-0748 ~ ~

(505)S45 9850 l Prepared for:

Ronaldo Jenkins ElectricalEngineering Branch Office ofNuclear Reactor Regulation - -- -

U. S. Nuclear Regulatory Commission Washington,DC 20555 USNRC JCN J.2503 i -

9901260483 990106 DR ADOCK 050002 9 ATTACHMENT

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TABLE OF CONTENTS:

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FORWARD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iii l

1.0 INTRODUCTION

. . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . 1 1.1 B ackground . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1.2 Objectives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1.3 Organization of Report . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 2.0 ASSESSMENT OF SPECIFIC LICENSEE RM RESPONSES . . . . . . . . . . . . 3 2.1 RAI Item 1: Use ofOutdated Methodology . . . . . . . . . . . . . . . . . . . . . 3 1 2.2 RAIItem 2: Life Impact Assessment for Nominally Overloaded Cables . 3 l 2.3 RAI Item 3: Fill Depth Discrepancies . . . . . . . . . . . . . . . . . . . . . . . . . . 4 3.0 SUhlMARY OF FINDINGS AND RECOMMENDATIONS . . . . . . . . . . . . . 5 l

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FORWARD The United States Nuclear Regulatory Commission (USNRC) has solicited the support of Sandia National Laboratories (SNL) in the review of utility submittals associated with fire protection and electrical engineering. This letter report represents the third in a series of SNL technica1 review reports associated wia the review ofcable ampacity assessment submittals from the Three Mile Island (nG) Unit I nuclear plant. In particular; the submittals under review deal with the assessment of ampacity loads for cable trays and conduits protected by Thermo. Lag 330-1 fire baniers. The original documents were submitted by the utility in response to USNRC Generic Letter 92-08. The current report documents review findings resulting based on a 6/24/97 licensee resportse to an USNRC RAI ofMay 8,1997. The current work was performed as Task Order 2, Subtask 4 of USNRC JCN J 2503.

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1.0 INTRODUCTION

1.1 Background

• This report represents the third in a sedes of technical review letter reports generated by SNL based on the review of cable ampacity assessment submittals forwarded to the USNRC by GPU Nuclear on behalf of the Three Mile Island Nuclear Station, Unit 1 (TMI). The history of the USNRC and SNL review efforts is summarized as follows:

March 29.1995: In response to USNRC Genede I.etter 92-08, TMI provided documentation of the licensee position regarding ampacity derating factors associated with its installed Thermo-Lag 330-1 fire barder systems.

Apdl 25,1996: SNL documented the initial results of a technical review of the licensee 3/95 submittal. SNL finds the licensee submittal to be incomplete and insufficient to conclude that ampacity has been adequately assessed.

July 5,1996: Based in part on the SNL review findings, a Request for Additional Information (RAI) was forwarded to the licensee by the USNRC.  ;

October 22,1996: The licensee provides its response to the 7/96 RAI. The submittal includes thorough documentation of the licensee assessment methods and results.

Apdl 10,1997: SNL completes a review of the 10/96 licensee submittal. '

One major finding is documented: SNL finds that the licensee has applied an outdated method of assessment (IPCEA P-46-426) to its cable tray _ . _

applications and recommends that reassessments be requested by the USNRC for seven specific cable installations using accepted industry methods of analysis (ICEA P-54-440).

May 8,1997: A second RAIis forwarded to the licensee by the USNRC.

June 24,1997: The licensee provides an initial response to the USNRC RAI of 5/97 including a bdef response to each of the three specific RAI items.

July 31,1997: The licensee provides a supplemental response to the 5/97

.RAI. This submittal includes an update to the licensee ampacity

.' calculations.

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", 1.2 Objectives The objective of the current review is to assess the adequacy of the licensee response to the May 8,1997 USNRC RAI. The relevant documents reviewed under the current efform are:

- Letter, June 24,1997, James W. Langenbach, GPU Nuclear /TMI to the USNRC Document Control Desk, item 6710-97-2260 with one atta^- *

- Istter, July 31,1997, James W. Langenbach, GPU Nuclear /TMI to the USNRC Document Control Desk, item 6710-97-2343 with one attachments as follows:

- Attachment 1: Calculation C-1101-770-E240-018 Revision 1, 1 l "Derating ofCable Ampacity To Raceway Fire Baniers".

SNL was requested to review these submitta's under the terms of the general technical support contract JCN J-2503, Task Order 2, Subtask 4. This letter report documents SNL's findings and recommendations regarding the acceptability of this licensee submittal to demonstrate that cables are operating witnin appropriate ampacity limits.

1.3 Organization ofReport Section 2 of this repon provides a point by point review ofthe licensee's specific RAI responses. Section 3 summarizes the SNL findings and recommendations.

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2.0 ASSESSMENT OF SPECIFIC LICENSEE RAI RESPONSES

g The USNRC RAI ofMay 8,1997 included three specific questions. The following .

sections prodde point-by-point reviews of the licensee's responses to these RAI items. l 2.1 RAI Item 1: Use of Outdated Methodology Synoosis of the RAI RAIItem 1 cited that the licensee had based its cable tray ampacity assessments on an outdated and superceded assessment methodology (IPCEA P-46 426).

The licensee was requested to provide re-analyses based on industry accepted methods (ICEA P-54-440) for any cables collocated with two or more other cables in a common tray and for which the previously applied method had demonstrated a margin ofless than 30% after application of the fire barrier derating. In particular, seven specific circuits meeting these criteria were identi5ed.

i Synopsis of the Licensee Response The licensee letter ofJune 1997 indicated that the -

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' calculation was being revised as requested. The submittal ofJuly 1997 provides the updated calculations.

Assessment ofResnonse- The updated documentation is very complete, well orgmaW.

and is fully adequate to re solve the identified concerns. Indeed, the licensee has not simply re-analyzed the seven cables identified in the RAI, but has apparently re-analyzed all of the 34 cables that were previously assessed using the older method. The implementation of the P-54-440 methodology appears to be complete and appropriate. l SNL " spot-checked" several of the licensee results and no errors were noted. The resuhs of this analysis demonstrated that of the 34 cables considered, only one is nominally overloaded. The overloaded cable (LS6) was previously identified by the licensee and is also the subject of RAI item 2 as discussed below.

Findings and Recommendations: SNL finds that the licensee has conducted appropriate -

ampacity assessments as requested in the RAI. No mistakes or omissions in the updated calculations were noted by SNL. Hence, SNL finds that this RAI item has been adequately resolved. No further actions regarding this RAI item are recommended.

2.2 RAI Item 2: Life Impact Assessment for Nominally Overloaded Cables Synopsis of the RAI: RAI Item 2 requested that the licensee provide a dermitive basis for the assessment of remaining life for any cable identified as nominally overloaded.

Synopsis of the Licensee Recoonse The licensee response notes that only one cable, LS6, was identified as nominally overloaded. A life assessment for this cable was provided that demonstrates a life expectancy extending until at least 1/30/1999 but not until end ofplant life; 9/1/2014. A survei!!ance procedure (OPS-S94) is cited as having implemented a monitoring scheme for the associated breaker using an elapsed time meter to monitor when the end oflife condition is reached (presumably based on hours of actual cable operation compared to the life expectancy). The licensee calculation also cites that

" Remedial follow up actions are required to assure cable LS6 life."

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'. Assessment of Resnonte The licensee's response appears fully adequate to rIsolve the Identi5ed concerns. The life expectancy calculation performed by the licensee is based on

.a widely accepted practices with regard to both the determination ofnominal operating temperature and the impact ofelevated temperature on cable life expectancy. 'While the licenses refers to non-specific " remedial actions" to be undertaken at some time in the future (probably cable replacement)it would appear that adequate procedures have been implemented to ensure that this cable will be appropriately monitored and replaced when necessary. -

Findines and Recommendatione SNL finds that the RAIitem has been adequately resolved. No funher actions regarding this RAIitem are currently r-nWed.

2.3 RAIItem 3:FillDepth Discrepancies Synopsis of the RAT: RAI Item 3 requested that the licensee resolve certain discrepancies noted by SNL involving the cable diameter, conductor counts, and cable Sils cited by the '

licensee.

Synoosis of the Licensee Resnonte The licensee response has noted the+. there was a discrepancy between the cable diameters cited in two different supporting documents.

This was cited as the basis for the discrepancies noted by SNL. Field measurements were made to verify which set ofvalues was correct, and the updated calculations have been performed using these correct diameters.

Assessment ofResoonte The licensee's response is fully adequate to resolve the identified concerns. The updated calculation provided with the July 1997 submittal provided enough information for SNL to verify the licensee fill depth calculations. No discrepancies in this regard were noted.

j Findings and Recommendations SNL finds that the RAIitem has been adequately ~ ~ -

resolved. No further actions regarding this RAI item are currently recommended.

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SUMMARY

OF FINDINGS AND RECOMMENDATIONS . [

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SNL finds that the licensee has adequately resolved all of the previously identified RAI '.

items. In particular, the licensee has re-analyzed all ofits fire barrier clad power cables in l

cable tray applications usi6g the accepted methods ofICEA P-54-440. With one exception, all cables were found to be operating within acceptable ampacity limits. SNL was able to verify several selected results (chosen at random) from the TMI calculations, and no errors or discrepancies were noted. A monitoring procedure for the one cable identified as nominally overloaded has been put in place to ensure that remedial actions are taken before the cable exceeds its life expectancy. On this basis, SNL recommends that the licensee has provided adequate consideration to the ampacity limits for fire barrier clad cables at TMI. No further interactions with the licensee are recommended.

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