ML20141A934

Responds to Util Responding to NRC RAI Re GL 92-08, Thermo-Lag 330-1 Fire Barriers. Encl Contractor Rept Identified Number of Open Issues & Concerns Requiring Clarification

ML20141A934
Person / Time
Site:	River Bend
Issue date:	05/12/1997
From:	Wigginton D NRC (Affiliation Not Assigned)
To:	Mcgaha J ENTERGY OPERATIONS, INC.
Shared Package
ML20140G669	List: ML20140G662 ML20141A934
References
GL-92-08, GL-92-8, TAC-M82809, NUDOCS 9705150062
Download: ML20141A934 (6)

Text

. . . ._ . . _

- i _ .o May 12, 1997 Mr. John R. McGaha, Jr.

Vice President - Operations Entergy Operations, Inc.

. River Bend Station P. O. Box 220' '

St. Francisville, LA 70775

SUBJECT:

' REQUEST FOR ADDITIONAL INFORMATION REGARDING THERM 0-LAG-RELATED AMPACITY DERATING ISSUES FOR RIVER BEND (TAC-NO. M82809)

Dear Mr. McGaha:

I By [[letter::RBG-43571, Provides Responses to 961016 RAI Re Ampacity Derating Including Supporting Draft Calculations G13.18.14.0-178,Rev 0, Ampacity Derating Factors for Thermo-Lag 330-1 & E-128, Rev 1, Ampacity Verification....Fire Protection Barrier|letter dated December 19, 1996]], Entergy Operations, Inc. (E01) submitted a response to the Nuclear Regulatory Commission (NRC) Request for Additional Information (RAI) related to Generic Letter (GL) 92-08, "Thermo-Lag 330-1 Fire Barriers," for River Bend Station, Unit 1. This office, in conjunction with

.our contractor, Sandia National Laboratories (SNL), has completed the review l of the response submittal, and has identified a nuuber of open issues and concerns (see enclosure) requiring clarification. ,

It is requested that E01 provide the information requested so that we can complete the review. If there are any questions in this regard, please let me-know. ,

Sincerely,

~

Original signed by David L. Wigginton, Senior Project Manager t Project Directorate IV-1 i Division of Reactor Projects III/IV Office of Nuclear Reactor Regulation i

Docket No. 50-458

Enclosure:

Request For Additional Information )

cc w/ encl: See next page k DISTRIBUTION:

\ -

Docket File. PUBLIC PD4-1 r/f C; Hawes. J. Roe D. Wigginton l A. Howell, RIV /,g {

E. Adensam (EGA1)

ACRS- 0GC (15B18) { .

Document Name: RB82809.RAI 0FC PM/PD4-1[f) l LA/PD4-1 NAME DWiggiM/vw CHawes (i m d DATE- 8 //l/97 5 /D/97 gj COPY, DES)NO l MFFICIAL RECORD COPY YES/N0 gh  ;

Q

.140051 )

9705150062 970512 "

PDR ADOCK 05000458 P PDR m ,

h ., en acru g  % UNITED STATES g

4 j NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. someHoot

\*****/ May 12,1997 l

l Mr. John R. McGaha, Jr. i Vice President - Operations i Entergy Oprrations, Inc.

River Benu Station i P. O. Box 220 St. Francisville, LA 70775 j

SUBJECT:

. REQUEST FOR ADDITIONAL INFORMATION REGARDING THERM 0-LAG-RELATED AMPACITY DERATING ISSUES FOR RIVER BEND (TAC NO. M82809)

Dear Mr. McGaha:

By [[letter::RBG-43571, Provides Responses to 961016 RAI Re Ampacity Derating Including Supporting Draft Calculations G13.18.14.0-178,Rev 0, Ampacity Derating Factors for Thermo-Lag 330-1 & E-128, Rev 1, Ampacity Verification....Fire Protection Barrier|letter dated December 19, 1996]], Entergy Operations, Inc. (E01) submitted a response to the Nuclear Regulatory Commission (NRC) Request for Additional Information (RAI) related to Generic Letter (GL) 92-08, "Thermo-Lag 330-1 Fire  ;

Barriers," for River Bend Station, Unit 1. This office, in conjunction with 1 our contractor, Sandia National Laboratories (SNL), has completed the review i of the response submittal, and has identified a-number of open issues and  !

concerns (see enclosure) requiring clarification.

It is requested that E01 provide the information requested so that we can complete the review. If there are any questions in this regard, please let me know.

Sincerely, i

_,. I David L gginton, Senior Project Manager Project Directorate IV-1 Division of Reactor Projects III/IV Office of Nuclear Reactor Regulation Docket No. 50-458

Enclosure:

Request For Additional Information cc w/ encl: See next page l

I r  ;, ' j

.Mr. John R. McGaha ,

LEntergyOperations,Inc. River Bend Station l cc:-

)'

Winston & Strawn Executive Vice President and i

1400 L Street, N.W. Chief Operating Officer- ,

a Washington, DC' 20005-3502 Entergy Operations, Inc. 1 P. O. Box 31995 l Manager -. Licensing ' Jackson, MS 39286 Entergy Operations, Inc.

River Bend Station General Manager - Plant Operations P. 0. Box-220 Entergy Operations, Inc.

)

St. Francisv111e,.LA 70775- River Bend Station i P. O. Box 220  :

Director .

St. Francisv111e, LA 70775  !

Joint Operations Cajun

10719 Airline Highway Director - Nuclear Safety ,

P. O. Box 15540 Entergy Operations,JInc.  ;

i Baton Rouge, LA 70895 River Bend Station '

P. O. Box 220 Senior Resident Inspector. St. Francisv111e, LA 70775  ;

P. O. Box 1050 j

.St. Francisv111e, LA 70775 Vice President - Operations Support i Entergy Operations, Inc. 1 President of West.Feliciana P. O. Box 31995 l Police Jury Jackson, MS 39286-1995  ;

P. O. Box 1921 1 St. Francisville, LA 70775 Attorney General i State of Louisiana ,

Regional Administrator, Region IV P. O. Box 94095 l

-U.S. Nuclear Regulatory Commission Baton Rouge, LA 70804-9095 l 611 Ryan Plaza Drive, Suite 1000 i Arlington, TX 76011 Wise, Carter, Child & Caraway' 1 P. O. Box 651  :

Ms. H. Anne Plettinger Jackson, MS 39205 i 3456 Villa Rose Drive i Baton Rouge, LA 70806 Vice President & Controller J Cajun Electric Power Cooperative i Administrator 10719 Airline Highway <

Louisiana Radiation Protection Division P.O. Box 15540 P. O. Box 82135 Baton Rouge, LA 70895 Baton Rouge, LA 70884-2135 i 2

l i

I l

1 i

l l

r ,

RE0 VEST FOR ADDITIONAL INFORMATION (RAI)

RIVER BEND STATION. UNIT 1 THERMO-LAG AMPACITY DERATING IS5UES (TAC NO. M82809)

1. The licensee has not yet identified what course of action will be taken to resolve those cables that were identified as overloaded for

~

application in the plant. The staff agrees with the Sandia National Laboratories (SNL) assessment that the National Electric Code overcurrent protection provisions [i.e., Articles 240-3(b) and 240-6] as described in the licensee's submittal dated December 19, 1996, cannot be used as a basis for the resolution of the overloaded cable issue (see Section 4.1.3 of the SNL letter report [ Attachment 1(a)] for details). In addition, the licensee is requested to estimate conservatively the remaining cable life for those cables that have operated under overloaded conditions.

. 2. SNL found that Calculation G13.18.14.0-178, which was included in the  ;

licensee submittal dated December 19, 1996, was significantly flawed in terms of the implementation of the thermal model. Please address the following points raised by SNL:

(a) SNL finds that the licensee has inappropriately applied convection coefficients for surface heat transfer in an unrestricted open (external) environment to the highly confined interior of the fire barrier systems analyzed. This observation applies to both the conduit and cable tray analyses. The licensee is requested to '

provide an explicit justification for any such cases that includes a discussion of item-to-item, item-to-barrier surface, and item-to-  !

wall / ceiling clearances. (See Sections 3.2.1 and 3.2.2 of the SNL letter report [ Attachment 1(a)) for details.)

(b) SNL finds that the licensee's treatment of external convection for cable tray systems is unnecessarily crude and does not adequately >

treat the differences associated with surface orientation. The licensee is requested to modify its thermal model so that more realisti: external convective heat transfer coefficients are

, derived. (See Section 3.2.3 of the SNL letter report [ Attachment 1(a)] for details.)

(c) SNL finds that the licensee treatment of internal heat transfer behavior within a conduit has not been adequately justified, appears to be inappropriate, and is likely non-conservative. The licensee '

is requested to modify its analysis methodology to conform to accepted practices for the analysis of cable-to-conduit heat transfer. (See Section 3.2.4 of the SNL letter report [ Attachment 1(a)) for details.)  ;

ENCLOSURE !

t i

o 1

t. %.

v (

.t 2- .

\

(d) SNL finds that the licensee has not' calculated radiation view- i i factors correctly, in particular, for those analyses involving .

multiple raceways in a common enclosure.- The licensee is requested

to correct its analysis in this regard. (See Section 3.2.5 of the  !

SNL letter report (Attachment 1(a)) for details.)  ;

(e) SNL finds that the licensee comparison of clad case ampacity limit estimates derived from its own thermal model to tabulated base line ,

ampacity limits is inappropriate. The licensee has failed to  !

demonstrate that its thermal model is consistent with the thermal  ;

models used to develop the standard tables, and consistency between the clad case and base line case analyses is. critical to the reliability and robustness of the calculations. The licensee is-  ;

4 requested to explicitly determine base line ampacity limits using a  ;

- thermal model consistent with that applied to the clad case  ;

analyses. -(See- Section 3.2.7 of the SNL letter report [ Attachment - l 1(a)] for details.) i F-(f) : SNL finds that the ampacity correction factors associated with the l

~

number of current carrying conductors in a conduit have either not been properly calculated or are still based 'on the older pre-1990 National Electric Code (NEC) correction factors. This item was also a concern identified in SNL's earlier review, and the licensee response to the question in Section 2.3 of the NRC staff's >

d October 16, 1996, RAI cited that the newer NEC correction factors would be used in all calculations. (See Section 3.2.6 of the SNL letter report (Attachment 1(a)) for details.)

(g) SNL finds that for cases involving multiple raceways (trays and/or 7 conduits) in a single enclosure, the licensee's independent

treatment of convective heat transfer between each of the raceways and the inner surface of the fire barrier system is inappropriate.

The licensee is requested to modify the thermal model to account for

' the simultaneous transfer of the total convective heat load from all sources. (See Section 3.2.8 of the SNL letter report [ Attachment 1(a)) for details.

i (h) SNL finds that the licensee calculations for single aluminum conduits may be unnecessary. The licensee could instead apply test data available from industry for steel conduits as-conservative estimates of the ADF for an aluminum conduit (provided, of course, that the fire barrier configurations are roughly equivalent). While this may actually, result .in less conservative estimates of the ,

derating impact as compared to the current licensee estimates, this would remove one significant source of uncertainty in.the licensee assessments, and would simplify both this calculation and the overall licensee submittal. The licensee is requested to consider whether to abandon its calculations for single aluminum conduits and to instead rely on industry data for steel conduits in any case in which an appropriately tested configuration can be identified for River Bend plant installations.

= m .. ..eer -

4w- , -n.-r-, ,,,,y- ,,.-n-- +-v- -

, e-- -

s a .,

3. It.is noted that Calculation E-218 includes the use of ampacity derating factors derived from Calculation G13.18.14.0-178, which SNL has determined to be significantly flawed in terms of model implementation.

The licensee should revise Calculation E-218 in light of any resolution for the concerns stated in Item 2 above. ,

4. The licensee has documented conduit cable fills as high as 124 percent in their December 19, 1996, submittal . It appears physically unrealistic to ,

have a conduit load of greater than 100 percent. The licensee is requested to explain this apparent inconsistency. ,

5. In their December 19, 1996, submittal, the licensee has documented numerous conduits that appear to be loaded in excess of the loading limits established in the NEC (generally limited to 40-53 percent loads -

depending on the conductor count). The licensee is requested to explain these apparent violations of the NEC. 7

, . Attachment 1(a): Letter report to U.S. NRC, Rev. O, dated March 21, 1997, i prepared by Steve Nowlen of Sandia National Laboratories.  !

i j

I l

l l

l f

-