ML17355A280

Rev 1,Ltr Rept, Technical Evaluation of Florida Power & Light Fire Barrier Ampacity Derating Assessment for St.Lucie & Turkey Point

ML17355A280
Person / Time
Site:	Saint Lucie, Turkey Point
Issue date:	09/30/1998
From:	Nowlen S SANDIA NATIONAL LABORATORIES
To:	Ronaldo Jenkins NRC (Affiliation Not Assigned)
Shared Package
ML17355A277	List: ML17355A276 ML17355A279 ML17355A280
References
GL-92-08, GL-92-8, NUDOCS 9904020220
Download: ML17355A280 (24)

Text

A Teclmical Evaluation ofthe Florida Power and Light Fire Barrier Ampacity Derating Assessments for St. Lucie and Turkey Point ALetter Report to the USNRC Revision 1

September 30, 1998 Prepared by:

Steve Nowlen Sandia National Laboratories Albuquerque, New Mexico 87185-0748 (505)845-9850 Prepared for:

Ronaldo.Jenkins Electrical Engineering Branch Ofhce ofNuclear Reactor Regulation U. S. Nuclear Regulatory Commission Washington, DC 20555 USNRC JCN J-2503 9904020220 990326 PDR ADQCK OS0002SO PDR ENCIOSURE 2

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TABLEOF CONTENTS:

Section

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1.0 INTRODUCTION

1.1 Background

'.2 Review Scopeand Objectives..

1.3 Organization ofReport 2.0 ST. LUCIE CALCULATIONS 2.1 Overview 2.2 Calculation PSL-OFJE-96-001 2.2.1 Overview...

2.2.2 Summary ofAugust 1997 SNL Findings and Recommendations 2.2.3 The Follow-Up RAIand Calculation PSI OFJE-96.-001.......

2.2.4 Summary ofFinal Findings and Recommendations 2.3 Calculation PTN-BFJM-96-005 2..

.3.1 Ovemew

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2.3.2 Summary ofAugust 1997 SNL Findings and Recommendations 2.3.3 The Follow-Up RAI and Calculation PTN-BFJM-96-005,......

2.3.4 Summary ofFinal Findings and Recommendations 3.0 TUIGCEYPOINT CALCULATIONS 3..1 Ovennew..............

3.2 Calculation PTN-BFJM-96-028 3..

.2.1 OveMew.....

3.2.2 Summary ofAugust 1997 SNL Findings and Recommendations

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3.2.3 RAIItem2.2.band CalculationPTN-BFJM-96-028..........

3.2 4 Summary ofFinal Findings and Recommendations 3.3 Calculation JPN-PTN-SEEP-96-011 3.3.1 Overview 3.3.2 Summary ofAugust 1997 SNL Findings and Recommendations 3.3.3 RAIItem 2.2.b and Calculation JPN-PTN-SEEP-96-011 3.3.4 Summary ofFinal Findings and Recommendations 3.4 Calculation PTN-BFSE-96-006 3.4.1 Overview and Objective...............

3.4.2 Summary ofAugust 1997 SNL Findings and Recommendations 3.4.3 The Follow-up RAIs and Calculation PTN-BFSE-96-006......

3.4.4 Summary ofFinal Findings and Recommendations

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3.5 Licensee Calculation PTN-BFJM-96-005 3.5.1 Overview 3.5,2 Summary ofFindings and Recommendations 4.0

SUMMARY

OF REVIEWFINDINGS ANDRECOMMENDATIONS....

4.1 Overall Findings and Recommendations for St. Lucie Plant 4.2 Overall Findings and Recommendations for Turkey Point Plant.......

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0 FORWARD The United States Nuclear Regulatory Commission (USNRC) has solicited the support of Sandia National Laboratories (SNL) in the review ofutilitysubmittals associated with fire protection and electrical engineering.

This letter report documents the results ofa SNL.

review ofa set ofsubmittals from Florida Power and Light (FPL) for the St. Lucie and Turkey Point nuclear power stations.

This revision reflects the licensee responses to concerns raised in the original review (Revision 0, August.1997). The subject submittals deal with the assessment ofampacity loads for cable trays and conduits protected by Thermo-Lag fire barriers.

This report focuses on a technical assessment ofthe licensee's calculations, and on an overall assessment ofthe adequacy ofthe licensee's ampacity treatment.

This work was performed as Task Order 4, Subtask 2 ofUSNRC JCN J-2503.

1.0 INTRODUCTION

1.1 Background

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This report is related to ampacity assessment submittals from two Florida Power and Light (FPL) nuclear plants; namely, St. Lucie Plant (SLP) Units 1 and 2, and Turkey Point Plant (TPP) units 3 and 4. The approach to ampacity assessment is quite similar for each of these two plants, and one ofthe supporting calculations submitted by FPL was common to both plants. However, in assessing the adequacy ofthese submittals Sandia National Laboratories (SNL) has reviewed each plant's documentation somewhat independently.

The original FPL submittals were provided in response to two preliminary USNRC Requests for Additional Information (RAIs); one for SLP dated 11/6/96, and one for TPP dated 1/29/97. The RAIs in each case were quite direct and requested (1) the supporting calculations cited as the basis for the licensee assessments and (2) additional justification for the extrapolation ofTexas Utilities (TUEC) test results to the FPL fire barriers.

The licensee responses were provided under FPL cover letters dated 12/19/96 (SLP) and 3/7/97 (TPP). Included in each response is a fairlyextensive set ofsupporting calculations including for SLP:

Calculation PSL-OFJE-96-001, "Cable Derating in Conduits withFire Barrier Coatings", Revision 1, Approved 12/96.

Calculation PTN-BFJM-96-005, "Fire Barrier Ampacity Correction Factors-Extrapolation ofTest Results for 3 Hour Barrier", Revision 0, Approved 4/96.

Calculation JPN-PSL-SEES-96-059, "Engineering Evaluation ofthe Application of Thermo-Lag to Meet R G. 1.75 Requirements", Revision 0, Approved 8/96.'nd for TPP:

Calculation PTN-BFJE-93-001, "Ampacity Derating Response to NRC GL 92-08 for Cables Routed in Conduit and Tray with Thermo-Lag 330-1 Fire Barrier System Coating", Revision 0, 7/90.~

Calculation PTN-BFJM-.96-028, "Fire Barrier ACF for T-Lag 330-1/770-1 Assemblies", Revision 6/94.

Calculation JPN-PTN-SEEP-96-011, "Review ofAmpacity Ratings for Power Cables in conduits and Trays with Thermo-Lag 330-1 Covering", Revision 6/94.

'As noted in the text below, this particular calculation is not in any way related to the ampacity assessments performed by the licensee, and has not been reviewed in detail by SNL.

~This document was cited by the licensee as ofhistorical interest only having been superceded by PN-PTN-SEEP-96-011, hence, SNL has not reviewed this calculation in detail.

Calculation PTN-BFM-96-005, "Fire Barrier Ampacity Correction Factors-Extrapolation ofTest Results for 3 Hour Barrier, Revision 6/94.

Calculation PTN-BFSE-96-006, "Ampacity Derating for Cables in Raceways and Boxes with Thermo-Lag 330 and with Thermo-Lag 330 w/Layer ofThermo-Lag 770 Fire Barrier Coating", Revision 6/94.

SNL originally reviewed these calculations in August 1997 as documented in Revision 0 ofthis letter report. In that review, SNL found that (1) the licensee had provided sufficient information to conclude that cables at the plants were being operated within acceptable ampacity limits, but that (2) the submittals did contain a number ofapparent discrepancies.

That is, despite the discrepancies noted SNL did have sufficient information available to re-analyze the effected cases and was able to show that the cited ampacities were acceptable.

Hence, while the overall conclusion was that the licensee ampacity loads were acceptable, it was recommended that the apparent discrepancies be brought to the attention ofthe licensee.

As a result, an additional follow-up RAIwas forwarded to each plant. This revision ofthe SNL review report includes consideration of the licensee responses to this second set ofRAIs. The most recent RAIresponse for TPP is contained in a licensee letter ofJune 30, 1998 (licensee item L-98-150) and the SLP re'sponse is contained in a licensee submittal dated June 26, 1998 (licensee item L-98-175).

Note that in this revision, SNL has deleted much ofthe detailed supporting information originally presented as a part ofthe August 1997 SNL review. This information can be found in Revision 0 ofthis report. The current revision (Revision 1) provides a summary overview ofthe previous favorable findings, and considered the licensee response to the apparent discrepancies noted in the earlier review as raised in the RAIs.

1.2 Review Scope and Objectives This letter report documents SNL's findings and recommendations resulting from a review ofthe licensee submittals as identified above.

This review has focused on assessing the technical merits ofthe licensee calculations.

The report also provides an overall assessment ofthe adequacy ofthe licensees treatment ofampacity loads for fire barrier clad cables.

It is important to note that, consistent with the statement ofwork for this effort, the SNL review has been limited to those portions ofthe utilitysubmittals directly related to the issue ofampacity derating.

The utilitysubmittals include documentation ofother aspects ofthe Thermo-Lag issue including quality control, material consistency, and the decision making process associated with installation offire barriers to meet the separation requirements ofRegulatory Guide 1.75. SNL has not reviewed these portions ofthe documents.,

~This is identical to one ofthe documents submitted by SLP as well.

1.3 Organization ofReport Section 2 provides an assessment ofthe licensee calculations associated'with SLP.

Section 3 ofprovides an assessment ofeach ofthe calculations for TPP.

Section 4 summarizes the SNL findings and recommendations for each ofthe two plants.

Section 5 identifies referenced documents.

2.0 ST. LUCIECALCULATIONS 2.1 Overview The SLP submittal originally reviewed by SNL in August 1997 included three calculations.

Ofthese, one dealt exclusively with cable separation criteria and the use offire barriers to meet these criteria, Calculation JPN-PSL-SEES-96-059.

This calculation was not reviewed by SNL. The other two calculations were reviewed by SNL:

Calculation PSL-OFJE-96-001, "Cable Derating in Conduits with Fire Barrier Coatings", Revision 1, Approved 12/96: This calculation documents the results ofa licensee ampacity margins assessment and is reviewed in Section 2.2 below.

Calculation PTN-BFJM-96-005, "Fire Barrier Ampacity Correction Factors-Extrapolation ofTest Results for 3 Hour Barrier": This calculation presents the licensee assessment ofthe ADF for upgraded fire barriers based on an extrapolation of test results from TUEC. This calculation is reviewed in Section 2.3 below.

2.2 Calculation PSI OFJE-96-001 2.2.1 Overview Calculation PSL-OFJE-96-001 is entitled Cable Derating in Conduits with Fire Barrier Coatings." This calculation represents a relatively straight-forward ampacity margins assessment for the fire barrier clad cables at SLP. Allofthe clad cables are. housed in conduits, and there are no clad cable trays. The fire barriers include both 1-hour and 3-hour configurations. Most installations are ofa standard configuration with the exception ofcertain cases where multiple conduits have been clad using a common fire barrier system.

The general approach to the margins assessment was based on a direct comparison of actual in-plant service loads to derated ampacity limits for the cables.

As is common, the analysis has excluded the consideration ofinstrument, control, and intermittent load power cables (such as valves).

-2.2.2 Summary ofAugust 1997 SNL Findings and Recommendations Based on SNL's August 1997 review, SNL found that the licensee's margins analysis approach as documented in Calculation PSL-OFJE-96-001 was an acceptable means of addressing the issues offire barrier ampacity derating. Further, SNL was provided with sufficient information to conclude that the fire barrier clad cables at SLP were operating within acceptable ampacity limits. Overall, SNL recommended acceptance ofthe method and results.

There were, however, two relatively minor points ofconcern identified as follows:

0 Baseline ampacity limits are taken from standard IEEE-835-1994 [1], a widely accepted industry trade standard applicable to this assessment.

One discrepancy in this practice was noted related to the selection ofbaseline values from the tables.

This discrepancy was raised in item 2.1.b ofthe follow-up USNRC RAI.

Fire barrier ADF values were based on TUEC ampacity tests, either directly or as extrapolated in a supporting calculation (see section 2.3), without consideration ofthe uncertainty associated with those test results; The licensee was asked to address this point in RAIitems 2.1.a and 2.l.c ofthe follow-up RAI. These two RAIitems are discussed in Section 2.3 below as 'they are primarily factors associated with the supporting calculation, Calculation PTN-BFJM-96-005. The findings presented in Section 2.3 also apply here and SNL does find that the concerns have been adequately addressed.

SNL was able to show that ultimately neither ofthese items would impact the overall results ofthe licensee assessments.

That is, even given the noted concerns, the conclusion that the SLP clad cables were operating within acceptable limits would not change.

However, SNL did recommend that the concerns be brought to the attention ofthe licensee.

This was, in fact, done and the licensee responses to the RAI is discussed in section 2.2.3 immediately below.

2.2.3 The Follow-Up RAI and Calculation PSL-OFJE-96-001 There'were three items raised in the follow-.up RAIto the licensee. Two ofthese items, 2.l.a and 2.1.c, were in fact primarily related to Calculation PTN-BFJM-96-005 as discussed in Section 2.3 below. RAIitem 2.1.b was directly related to Calculation PSL-OFJE-96-001.

This RAIitem and the licensee response are summarized as follows:

RAIItem 2.l.b noted that the licensee had used baseline ampacity for cables under "no sun - 2 fUs" installation conditions and that this was contrary to accepted practice.

The licensee was asked to either apply the "no'sun - 0 ft/s" conditions, or to justify the assumption of2 ft/s continuous air flow.

The licensee response includes updated calculations that were performed using the "no sun - 0 ft/s" conditions as requested.

As expected all cables were still found to be operating at acceptable ampacity limits.

SNL finds that the updated calculations fullyaddress the identified concern.

No further actions on this RAIItem are'recommended.

2.2.4 Summary ofFinal Findings and Recommendations SNL finds that the licensee has fullyaddressed all ofthe identified concerns related to Calculation PSL-OFJE-96-001.

As was noted in the August 1997 review, SLP has provided sufticient information to conclude that the fire barrier clad cables. at SLP are operating within acceptable ampacity limits..The revised calculations simply provide a more solid basis for this conclusion and resolve any uncertainty in this regard.

SNL recommends acceptance ofthe licensee calculations and findings without further interaction.

2.3 Calculation PTN-BFJM-96-005 2.3.1 Overview Calculation PTN-BFJM-96-005 is entitled "Fire Barrier Ampacity Correction Factors-Extrapolation ofTest Results for 3 Hour Barrier". The purpose ofthe calculation is to estimate the fire barrier ADF for the 3-hour fire barriers at SLP based on the extrapolation of 1-hour system test results. In practice, calculations were performed for both conduits and cable trays, although for SLP it would appear that only the conduit results have been applied (no clad cable trays are identified in the SLP margins analysis).

The cable tray results were however used in the TPP assessments.

2.3.2 Summary ofAugust 1997 SNL Findings and Recommendations In the August 1997 review, SNL found that in principal the thermal model used in Calculation PTN-BFJM-96-005 was technically sound, and no discrepancies in its application were identified. There were two points ofconcern related to the use by SLP ofthe TUEC test results as the basis for the calculations:

The licensee failed to consider uncertainty in the TUEC test results deriving from the fact that different physical test specimens were used for the baseline and clad tests.

This was raised as RAIItem 2.1.a.

The licensee failed to consider uncertainty in the TUEC tests deriving from inductive heat losses.

This was raised as RAIItem 2;1.c.

2.3.3 The Follow-Up RAI and Calculation PTN-BFJM-96-005 There were three items raised in the follow-up RAIto the licensee. Two ofthese items, 2.l.a and 2.1.c, were related to Calculation PTN-BFJM-96-005.

These RAI items and the licensee response are summarized as follows:

RAIitems 2:l.a related to uncertainties in the TUEC tests used by SLP that were not considered by in the analysis. In particular, uncertainty was introduced in the tests due to the fact that TUEC used physically different specimens for the clad and baseline tests. In Item 2.1.a the licensee was asked to consider more recent test results for other industry sources or to include the uncertainty bounds in application ofthe TUEC data.

The licensee response indicates that the calculations have been updated using the FPL test results rather than the TUEC results.

The licensee did conclude

,that these tests were applicable to SLP. As expected, the results still.show that the cables at SLP are operating-within acceptable ampacity limits.

SNL finds that the updated calculations fullyaddress the identified concerns.

No further actions on this RAI]tern are recommended.

RAIItem 2.1.c noted that the licensee had not addressed the concerns related to inductive heating in its analysis ofthe TUEC tests.

The licensee was requested to

either consider other industry test results ofuse the more conservative ADF values that include consideration ofuncertainty in the TUEC tests.

As noted in regard to Item 2.1.a above, the licensee has updated the calculation using data from the FPL tests.

SNL finds that the updated calculations fullyaddress the identified concerns.

No further actions on this RAI Item are recommended.

2.3.4 Summary ofFinal Findings and Recommendations SNL finds that the licensee has fullyaddressed all ofthe identified concerns related to Calculation Calculation PTN-BFJM-96-005.

SNL recommends acceptance ofthe licensee calculations and findings without further interaction.

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3.0 TURKEYPOINT CALCULATIONS 3.1 Overview The original Turkey Point Plant (TPP) submittal included five supporting calculations:

(Calculation PTN-BFJE-93-001) had been superceded and was included only for historical interest.

This calculation was not reviewed by SNL in any detail.

Calculation PTN-BFJM-96-028, "Fire Barrier ACF for T-Lag 330-1/770-1 Assemblies": The stated purpose ofthis calculation is to extrapolate TUEC ampacity test results for 1-hour and 3-hour installations to the TPP installations involving Thermo-Lag 770-1 upgrades.

This calculation is reviewed in detail in Section 3.2.

Calculation JPN-PTN-SEEP-96-011, "Review ofAmpacity Ratings forPower Cables in conduits and Trays with Thermo-Lag 330-1 Covering": This calculation presents the results ofthe licensee evaluation ofindividual cable ampacity loads in light ofthe anticipated fire barrier ADF impact. This calculation has been reviewed in detail as discussed in Section 3.3.

Calculation PTN-BFSE-96-006, "Ampacity Derating for Cables in Raceways and Boxes with Thermo-Lag 330 and with Thermo-Lag 330 w/Layer ofThermo-Lag 770 Fire Barrier Coating": This calculation deals with the addition ofa 770-1 upgrade to existing installations.

The calculation has been reviewed in detail as discussed in Section 3.4 below.

Calculation PTN-BFJM-96-005, was common with a submittal from SLP. SNL's original 8/97 review evaluated this calculation in the context ofthe SLP submittal (see Section 2.3 above) and noted that the same findings also applied directly to TPP. The licensee response to identified concerns is discussed in Section 3.5 below.

3.2 Calculation PTN-BFJM-96-028 3.2.1 Overview Calculation PTN-BFJM-96-028 is entitled "Fire Barrier ACF for T-Lag 330-1/770-1 Assemblies."

The stated purpose ofthis calculation is to extrapolate TUEC ampacity test results for nominal 1-hour and 3-hour Thermo-Lag 330-1 single layer installations for cable tray and conduits to the TPP installations involving Thermo-Lag 770-1 overlay upgrades.

The calculation was essentially identical in approach and implementation to the thermal model employed in Calculation PTN-BFJM-96-005 which was reviewed in the context of the SLP submittal as documented in Section 2.3 above.

The TPP version had basically been extended by comparison to additional test results (tests by TVA)

3.2.2 Summary ofAugust 1997 SNL Findings and Recommendations As a general finding, SNL concluded in August 1997 that the approach to assessment used by the licensee in Calculation PTN-BFJM-96-028 was technically appropriate.

Further, SNL found that the licensee has established an adequate basis ofthermal similarity for the extrapolation ofthe TUEC conduit test results, and for the direct application ofthe TVA test results for the upgraded tray barriers. Two minor discrepancies were noted by SNL in the August 1997 review and were raised in the USNRC follow-up RAI. These items are discussed in Section 3.2.3 immediately below.

3.2.3 RAIItem 2.2.b and Calculation PTN-BFJM-96-028 There were two minor discrepancies noted by SNL in regard to calculation PTN-BFJM-96-028, and these two items were raised as a part ofitem 2.2.b ofthe follow-up USNRC RAI. In the August 1997 SNL review it was concluded that neither ofthese items had actually compromised the calculation, but it was recommended that they be brought to the attention ofthe licensee.

The licensee has responded to each ofthe two items suf5ciently to resolve any remaining uncertainty as summarized immediately below:

The first apparent discrepancy noted by SNL was that in the analysis ofthe cable tray case the assumed thickness ofthe TVAinstalled fire barriers appeared to be in error.

The licensee response has clarified that the test being simulated in this particular calculation is not TVATest Item 7.1 as had been assumed by SNL. Rather, the test in question is an alternate TVA/Omega Point test described in a journal article attached to the licensee calculation. The cited thickness values are appropriate for the cited test.

The licensee response has fullyresolved the apparent discrepancy. It is now clear that the licensee calculation is fullyconsistent with the intended test simulation.

There are no further unresolved items related to this concern.

In one table ofresults, Sheet 6 from the original submittal, it appeared that there was a typographical error in the cited thickness ofthe 330/770 upgrade system (the last line in the table). The table cited a value of0.75" when the fullthickness ofthe upgraded barrier was 2".

The licensee response has clarified that each case presented in Sheet 6 is actually presented in a "cumulative eFect" format. That is, the cited 0.75 thickness in the last line ofthe table is added to the previous lines 1.25" thickness to obtain the full2" thickness.

It is now clear that the apparent discrepancy was simply a matter ofmis-interpretation ofthe table values by SNL. The licensee response has fully resolved the apparent discrepancy, and it is now clear that the licensee calculations are fullycorrect as presented.

There are no further unresolved items related to this concern.

3.2.4 Summary ofFinal Findings and Recommendations As noted in 3.2.2 above, in August 1997 SNL found the licensee calculation to be technically appropriate, but noted two minor apparent discrepancies.

The licensee response to RAI Item 2.2.b ofthe follow-up USNRC RAI has fullyresolved the apparent discrepancies.

It is now clear that the calculation has been properly executed, and that the apparent discrepancies were merely the result ofmis-interpretation by SNL ofcertain elements ofthe licensee results tables.

SNL can now recommend, without qualification,

'hat the results ofCalculation PTN-BFJM-96-028 are appropriate.

There are no further unresolved concerns related to this calculation.

3.3 Calculation JPN-PTN-SEEP-96-011 3.3.1 Overview Calculation JPN-PTN-SEEP-96-011 is entitled "Review ofAmpacity Ratings for Power Cables in Conduits and Trays with Thermo-Lag 330-1 Covering." The objective ofthe calculation is to assess ampacity loads on individual cables when clad with nominal (non-upgraded) 1-hour and 3-hour Thermo-Lag barrier systems.'his assessment includes consideration ofthe fire barrier ACF factors as estimated in the supporting Calculation PTN-BFJM-96-005 (this calculation was discussed in the context ofthe SLP submittal as presented in Section 2.3 above).

The approach to the direct ampacity analysis is virtually identical to the methodology applied to SLP as described in Section 2.2 above.

The licensee has determined the ampacity load and physical installation characteristics ofeach ofthe identified power cables ofinterest.

Baseline ampacity limits are determined, and applicable derating factors are applied to estimate the derated ampacity limit. For conduits the derating factors include a fire barrier ACF, a temperature correction for an 85'C conductor temperature (vs. the more common 90'C conductor temperature), and additional factors for grouping ofconductors within a common conduit and for the grouping ofconduits are also applied.

For cable trays it appears that only the fire barrier ACF has been applied. The resulting actual load ampacity is then compared to the estimated derated ampacity limitfor a final assessment ofacceptability.

In addition, the licensee has also documented certain supplemental calculations ofthe heat load for the individual cables and for each cable tray or conduit as a whole. This is put forth as a "final check" on acceptability, and has not been utilized as a primary basis for acceptability assessment.

This is essentially a "Watts per foot" type ofanalysis.'s SNL has noted in past reviews, the "Watts/foot" method ofanalysis is not technically adequate

" Note that cables clad with upgraded barriers (330/770 systems) are addressed separately in Calculation PTN-BFSE-96-006 (see Section 3.4 below).

This method has been encountered in previous review efforts conducted under this USNRC JCN. It is known most commonly as the "watts/foot" method and is an early method ofanalysis that has since been discredited.

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for ampacity assessments ofindividual cables.

In this case it is quite clear that the licensee has not put these calculations forth on such a basis; hence, SNL has taken no specific exceptions to this part ofthe calculations.

However, SNL also has given essentially no credit to these supplemental assessments in making our own recommendations regarding the technical acceptability ofthe licensee submittals.

SNL finds that the margins assessment approach is sufficient in and ofitselfto demonstrate the acceptability ofin-plant service loads.

3.3.2 Summary ofAugust 1997 SNL Findings and Recommendations Overall, SNL found the ampacity margins assessment ofCalculation 3PN-PTN-SEEP 011 to be appropriate to its stated purpose, to have been properly implemented, and that these margins calculations were sufficient in and ofthemselves to justify the ampacity loads.

SNL further recommended that the supplemental "Watts/foot" based calculations not be credited at all. However, SNL also found these supplemental calculations to be unneeded and this finding did not compromise the overall conclusion that the licensee had demonstrated adequate ampacity margin..

Given these general conclusions, SNL did identify three apparent discrepancies in the calculation. The licensee was asked to resolve the apparent discrepancies in the USNRC follow-up RAI, Item 2.2.b. These three items and the licensee response to this RAIare

'iscussed in Section 3.3.3 immediately below.

3.3.3 RAIItem 2.2.b and Calculation JPN-PTN-SEEP-96-011 SNL identified three apparent discrepancies in the licensee calculations, and the licensee was asked to address these discrepancies in Item 2.2.b ofthe follow-up USNRC RAI.

The concerns and licensee responses are summarized as follows:

There was no documentation on how the licensee obtained the cited baseline ampacity limits for cable trays. Further, based on a simple comparison ofthe licensee cited values to those obtained by SNL using the ICEAP-54-440 methodology certain ofthe licensee cited values'appeared non-conservative.

The licensee response to this item states that the baseline ampacity values were taken from the original design calculations prepared in 1985 and 1990.'he licensee further notes that "Itis common practice to use prior calculation results as a basis for new calculations in lieu ofperforming duplicate calculations.

As such, these values are consistent with the design basis for Turkey Point and are considered reasonable and conservative."

The licensee response "dodges" the question entirely. The licensee was asked to verifythat the cited baseline ampacity..values were appropriate and..

were consistent with accepted methods ofpractice. The licensee has offered no new information that contributes to the technical resolution ofthis concern.

This concern remains unresolved.

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In one particular cable tray case study, tray 4AXT10, the licensee applied a baseline ampacity calculation methodology from IPCEA PA6-426 that has been specifically superceded by the ICEAP-54-440 methodology.

Further, in one particular case a 3-conductor cable was evaluated based on single conductor ampacity limits when the more restrictive 3-conductor values should have been used.

The licensee response to this concern acknowledges that the P-46-426 methods were used in early design calculations, and that the resulting values have been retained in more recent calculations.

The date ofthe original calculation (5177-304-E005) is not identified, but the re-analysis ofampacity loads considering fire barrier derating were apparently performed in 1985.

The licensee concludes that "The use ofIPCEA P-46-426 in lieu ofIPCEA P-54-440 is considered appropriate in order to remain consistent with the methodology used in the original calculation."

With regard to the use ofPA6-426 methods, the licensee response does not address the identified concern.

Basically, the licensee has put forth the argument that because P-46-426 was used in the past, its continued use is appropriate.

An assessment ofthe validityofthis argument ultimately lies outside the expertise ofthe SNL reviewers.

From a technical standpoint, the licensee position is not defensible.

That is, P-54-440 clearly and explicitly states that the methods ofP-46-426 for random fillcable trays were to be superceded by the new methods.'ndeed, P-54-440 was originally published

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i.'972, the same year that TPP began operations.

Hence, the random fill methods from P-46-426 have been considered inappropriate methods of analysis since 1972. Also note that this change in accepted methods can result in significant reductions in baseline ampacity using the newer methods ofP-54440 as compared to those obtained using the P-46-426 methods.

The licensee argument is basically a "legalistic" argument that boils down to "grandfathering" ofthe original calculations despite changes in accepted methods.

No discussion ofthe use ofsingle conductor ampacity limits in the evaluation of3-conductor cables was provided in the licensee response.

Even putting questions ofthe acceptability ofthe P-46-426 methods, ifSNL's observation is indeed correct and 3-conductor cables were analyzed based on single conductor ampacity limits, then this would constitute a clear mistake in the evaluation.

The licensee is again relying on the assumption that older calculations would not be questioned in later calculations, and this fails to address the concern.

SNL is not in a position to judge the "legal" or "regulatory" merits ofthe

.licensee position regarding "grandfathering" ofthe outdated calculations.

One factor that should be considered here, however, is when the original calculations were actually performed. Ifperformed after 1972, then the licensee position is not defensib]e because by 1972 the new standards of practice had already been published.

Further, the licensee has not addressed

~ See the section ofthe standard entitled "History" on page iii.

12

SNLs observations that indicate mistakes may have been made in the original assessments even ifthe question ofacceptability ofthe P-46-426 methods is put aside.

This concern remains unresolved.

In the assessment ofconduit ampacity limits, the licensee applied conduit conductor count correction factors that inherently credit a 50% diversity without explicitlyjustifying that this level ofdiversity does in fact exist in the impacted conduits.

The licensee response cites that the conductor count correction factors were those used in an earlier calculation (5177-EF-15, date not given) and cites that "justification for load diversity has been established in the original design calculations."

The licensee has not provided the earlier calculations for review; hence, the licensee's statements cannot be verified. However, the statements are quite clear that the fact that the correction factors include diversity effects is acknowledged by the licensee and that in the view ofthe licensee diversity factors have been substantiated.

On this basis, SNL finds the concern to be resolved.

3.3.4 Summary ofFinal Findings and Recommendations As per the findings ofthe August 1997 review, SNL finds the overall approach to analysis documented in Calculation 3'-PTN-SEEP-96-011, in an ofitself, to be acceptable.

The only exception to this is with regard to the supplemental "Watts/foot" method calculation that SNL finds to be unneeded and recommends not be credited.

However, there were concerns identified in SNLs August 1997 review regarding the validity ofthe cited baseline ampacity limits that were used as inputs to this calculation.

Based on the licensee response it is now clear that these values were taken directly from earlier design calculations.

The licensee was asked to respond to three related points of concern in Item 2.2.b of.the follow-up USNRC RAI. Their response basically calls for "grandfathering" ofthe earlier calculations.

That is, the licensee cites that the earlier calculations were a part ofthe plant's original design basis and that they should be acceptable for use in newer calculations on this basis.

SNL is not qualified to judge the "legal" or "regulatory" merits ofthis argument.

From a purely technical standpoint this argument is without merit, and SNL would recommend that it not be accepted.

To clarify, the licensee response to RAIItem 2.2.b failed to provide a technical resolution for two ofthe three identified points ofconcern; namely:

some ofthe cited baseline ampacity limits were optimistic in comparison to values obtained using current practices, and for certain cases the licensee had cited use ofthe IPCEA P-46-426 cable tray ampacity methods that have been superceded by ICEAP-54-440 and, even given 13

the older method, SNL noted apparent mistakes in those analyses (single-conductor ampacity limits were applied to multi-conductor cables).

It now clear that these two points are closely related.

That is, based on the licensee response it is now clear that the optimistic cable tray ampacity values (point 1 above) are a direct result ofthe use ofthe P-46-426 methods (point 2 above).

Further, the licensee did not address at all the concern that mistakes appear to have been made in the analyses.

On purely technical grounds, SNL finds that the licensee practice is not consistent with current practice; hence, recommends that it is not acceptable.

The unresolved technical concerns can be summarized as follows:

The licensee has cited Calculation 5177-304-E005 as the basis for the evaluation of baseline ampacity limits for cables at TPP. In the case ofrandom fillcable trays the analysis apparently relies on the methods ofIPCEA P-46-426, and even given these methods it appears that mistakes may have been made in the analyses (it appears that single-conductor ampacity limits have been used in the analysis ofmulti-conductor cables).

The methods ofIPCEA P-46-426 as applied to random fillcable trays were explicitly superceded in 1972 by ICEAP-54-440.

The newer methods establish more restrictive limits on cable tray ampacity limits than those obtained using P-46426.

The methods ofP-54-440 represent the current accepted practice in industry. The continued reliance by TPP on the P-46-426 methods and the failure to address potential errors in the application ofthose methods cannot be justified on technical grounds.

SNL recommends that it is within the purview ofthe USNRC, rather than SNL, to decide the merits ofthe licensee's "legalistic" rational for using an outdated method ofanalysis and results that may contain mistakes in the assessment ofbaseline ampacity limits for random fillcable trays. That is, willthe USNRC accept use ofthe outdated methods (P-46-426) and potentially erroneous results even given the method based on "grandfathering" ofthe original plant design calculations or should this argument be rejected?

Ifthe licensee's "legalistic" argument for "grandfathering" ofthe original calculations is rejected, then SNL further recommends that the USNRC ask the licensee to (1) review the existing applications using currently accepted methods ofanalysis for the assessment of baseline ampacity values and (2) perform any future evaluations using current methods of accepted practice. In either case it is also recommended that the USNRC ask the licensee to review the earlier design calculations to ensure that no mistakes were made in these calculations (e.g., such as the single-versus multi-conductor cable ampacity question)...

Once again note that the licensee provided sufticient information for SNL to independently verify, using currently accepted methods ofanalysis, that the clad cables at TPP are operating within acceptable ampacity limits. This finding derives from SNL's August 1997 review, and remains unchanged.

The unresolved concerns identified here are issues primarily impacting the technical validity and defensibility ofthe licensee's compliance documentation.

That is, updating the methods ofanalysis willnot change the outcome of 14

the assessments, existing cable ampacity loads willstill'be found to be acceptable; rather, the abandonment by the licensee ofsuperceded methods and the adopting ofcurrent methods would make the supporting compliance documents defensible from a technical standpoint. It should also be noted that, ifnot addressed by the licensee, the unresolved concerns could adversely impact future plant fire protection design changes and the assessment ofplant life extension issues as they relate to the assessment ofcable aging.

This is because the methods ofanalysis currently applied by the licensee result in optimistic assessments ofcable ampacity limits. It is only the apparent availability ofa significant ampacity margin in the original plant design that led to the overall finding that under current conditions the existing ampacity loads are acceptable.

3.4 Calculation PTN-BFSE-96-006 3.4.1 Overview and Objective Calculation PTN-BFSE-96-006 is entitled "Ampacity Derating for Cables in Raceways and Boxes with Thermo-Lag 330 and with Thermo-Lag 330 w/Layer ofThermo-Lag 770 Fire Barrier Coating." The objective ofthis calculation is to re-assess the ampacity margins for cable in applications that have been upgraded beyond the nominal 1-hour or 3-hour barrier installations (i.e., those considered in Calculation 96-011). The cited ACF factors for the upgraded barriers are cited as deriving from both Calculation 96-028 and 96-005.

The approach to analysis is nominally identical to the margins assessments performed in Calculation 96-011 as discussed in Section 3.3 above.

The primary difference lies in the nature ofthe fire barriers under analysis.

The only other significant difference between this and the previous margins assessments is that an alternative definition ofthe margin has been employed.

In fact, in'this calculation the licensee does not present the results in the form ofan available margin, but rather, cites the actual in-plant ampacity load as a fraction ofthe allowable ampacity load. This is, in effect, a margins assessment, but should be viewed as an ACF-based margin as compared to an ADF-based margin. That is, the cited load fractions can be viewed directly as the maximum allowable ACF above and beyond the nominal assumed fire barrier derating that could be accepted by a given cable.

There is nothing wrong with this approach, but it is both somewhat unusual, and different from the method used in the other FPL margins assessments; hence, it is noted here for clarity.

3.4.2 Summary ofAugust 1997 SNL Findings and Recommendations In general, SNL found the approach to margins assessments as documented in Calculation PTN-BFSE-96-006 to be appropriate and acceptable.

SNL did identify one minor discrepancy associated with this calculation. This was related to the application ofconduit conductor count correction factors that inherently credit a 50% diversity without adequate justification. However, SNL also found that only two ofthe licensee conduits were.

impacted by this discrepancy,.and that in those cases the available margin was adequate to allow for the more conservative correction factors.

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3.4.3 The Follow-up RAIs and Calculation PTN-BFSE-96-006 As a part ofRAI 2.2.b the licensee was asked about the use ofolder diversity based conduit conductor count correction factors in the assessments.

The licensee response has been discussed in detail in Section 3.3.3 above.

3.4.4 Summary ofFinal Findings and Recommendations SNL finds that the margins analysis methods set forth in Calculation PTN-BFSE-96-006 are technically sound and appropriately executed.

SNL recommends the acceptance of this approach as an appropriate method for demonstrating that the cables at TPP are operating within acceptable ampacity limits.

I Note that to some extent this calculation is adversely impacted by the concerns discussed in Section 3.3.3 and 3.3.4 above as regards Calculation JPN-PTN-SEEP-96-011.

That is, Calculation PTN-BFSE-96-006 is also dependent on the use ofbaseline ampacity values from the earlier plant design calculations, and the technical validityofthose values has been questioned by SNL. However, as noted in the August 1997 review, the licensee provided sufhcient information for SNL to independently verify, using currently accepted methods, that the clad cables at TPP are operating within acceptable ampacity limits.

3.5 Licensee Calculation PTN-BFM-96-005 3.5.1 Overview The details ofCalculation PTN-BFM-96-005 have been discussed in Section 2.3 above.

This calculation is actually common to both the SLP and TPP submittals. Allofthe findings and recommendation cited above in the context ofthe SLP submittal also apply directly to the TPP submittal.

3.5.2 Summary ofFindings and Recommendations As discussed in greater detail in Section 2.3 above, SNL finds the licensee calculations

'ocumented in the revision to Calculation PTN-BFM-96-005 to be appropriate and recommends their acceptance by the USNRC. Allpotential concerns regarding uncertainty in the cited validation case examples have been adequately resolved by comparison to alternate data sources.

No further actions related to this specific calculation are recommended.

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4.0 SUMhGQ<Y OF REVIEWFINDINGS ANDRECOMMENDATIONS I

4.1 Overall Findings and Recommendations for St. Lucie Plant SNL finds that the licensee has fullyresolved all ofthe concerns identified in our August 1997 review ofthe SLP fire barrier ampacity derating analyses.

SNL further finds that the licensee has provided a fullyadequate basis for concluding that all ofthe fire barrier clad cables at SLP are operating within acceptable ampacity limits. SNL recommends that the SLP submittals be accepted as a complete and appropriate basis for resolution ofthe ampacity derating concerns raised in Generic Letter 92-08 without need for further interactions.

4.2 Overall Findings and Recommendations for Turkey Point Plant As documented in the August 1997 SNL review report, SNL finds that the TPP approaches to analysis as documented in the five supporting calculations reviewed by SNL, in and ofthemselves, were all acceptable and appropriate.

In particular, SNL made the following observations and findings:

The licensee thermal modeling efforts were found to have been well thought out and well executed.

The licensee ampacity margins methods were found to represent an adequate basis for the resolution ofthe ampacity loading questions originally raised by the USNRC.

Based on both the licensee calculations and independent calculations performed. by SNL, SNL fmds that sufficient information has been provided to concluded that the fire barrier clad cables at. TPP are operating within acceptable ampacity limits.

There was only one minor aspect ofthe actual supporting calculations that SNL did take exception to. SNL finds that the supplemental calculations based on the "Watts/foot" method as presented in Calculation JPN-PTN-SEEP-96-011 were not needed to support the final conclusions, and recommends that they not be credited by the USNRC. This does not adversely impact the other findings ofthis review; these calculations are simply unnecessary.

These findings remain unchanged.

However, in the August 1997 review SNL did note a number ofdiscrepancies in the licensee supporting calculations.

The cited discrepancies were the subject ofa follow-upRAI.

The licensee response to this follow-up RAI has left two points ofconcern from one ofthe RAIitems unresolved; namely, RAIItem 2.2.b, points ofconcern 1 and 2 as related to Calculation JPN-PTN-SEEP-96-011.

These. concerns relate to the basis for the cited cable tray baseline ampacity limits. The licensee response states that the cited baseline ampacity limits are taken directly from an earlier calculation that was not submitted for review and that the results ofthat earlier calculation were not questioned nor updated. No 17

direct technical resolution for the identified concerns was provided.

Instead, the licensee is relying on the fact that the earlier calculations are a part ofthe plant's original design basis and assumes that they are acceptable for use in subsequent calculations on that basis alone.

On purely technical grounds, SNL finds that the licensee practice in determining baseline ampacity limits for random fillcable trays is not consistent with current practice, and further, that the licensee has applied a method ofanalysis that is more optimistic than accepted current practice.

Hence, SNL recommends that the licensee approach is not acceptable.

The unresolved technical concerns can be summarized as follows:

The licensee has cited Calculation 5177-304-E005 as the basis for the evaluation of baseline ampacity limits for cables at TPP. The analysis is stated to be based on the methods ofIPCEA P-46-426, and even given these methods it appears that mistakes may have been made (it appears that single-conductor ampacity limits have been used in the analysis ofmulti-conductor cables).

The methods ofIPCEA P-46-426 as applied to random fillcable trays were explicitly superceded in 1972 by ICEAP 440. The newer methods establish more restrictive limits on cable tray ampacity limits than those obtained using P-46-426.

The methods ofP-54-440 represent the current accepted practice in industry. The continued reliance by TPP on the P-46-426 methods and the failure to address potential errors in the application ofthose methods cannot be justified on technical grounds.

In effect the licensee's response boils down to a "legalistic" argument for "grandfathering" ofthe original calculations. It is beyond the expertise ofthe SNL reviewers to assess the regulatory merits ofthis argument; this is a decision that lies within the purview ofthe USNRC rather than SNL. Ifthe argument is rejected, then SNL recommends that the USNRC ask the licensee to (1) review the existing random fillcable tray applications using currently accepted methods ofanalysis for the assessment ofbaseline ampacity values and (2) perform any future evaluations using current methods ofaccepted practice. Whether or not the USNRC accepts use ofthe outdated methods, it is also recommended that the USNRC ask the licensee to review the earlier design calculations to ensure that no.:

mistakes were made in these calculations (e.g., such as the single-versus multi-conductor cable ampacity question raised in the RAI).

Once again note that the licensee provided sufficient information for SNL to independently verify, using currently accepted methods ofanalysis, that the clad cables at TPP are operating within acceptable ampacity limits. Hence, the unresolved concerns are issues primarily impacting the technical validity and defensibility ofthe licensee's compliance documentation.

The concerns could also impact future plant fire protection design changes and the assessment ofplant life exte'nsion issues as they relate to the assessment ofcable aging.

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0

5.0 REFERENCES

1. IEEE Standard Power Cable Ampacity Tables, IEEE 835-1994, Sept. 1994.

2.

Power Cable Ampacities, IPCEA P-46-426, AIEE S-135-1, a joint publication ofthe Insulated Power Cables Engineers Association (now ICEA) and the Insulated Conductors Committee Power Division ofAIEE (now IEEE), 1962.

3.

Ampacities ofCables in Open-Top Cable Trays, ICEAP-54-440, NEMAWC 51, 1986.

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