ML20137E451

Forwards SE Re Revised Response to NRC Bulletin 88-08, Thermal Stresses in Piping Connected to Reactor Coolant Sys, for Plant,Units 1 & 2

ML20137E451
Person / Time
Site:	South Texas
Issue date:	03/24/1997
From:	Alexion T NRC (Affiliation Not Assigned)
To:	Cottle W HOUSTON LIGHTING & POWER CO.
Shared Package
ML20137E454	List: ML20137E451 ML20137E486
References
IEB-88-008, IEB-88-8, TAC-M93822, TAC-M93823, NUDOCS 9703270238
Download: ML20137E451 (5)

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0 f  %>% UNITED STATES NUCLEAR REGULATORY COMMISSION f WASHINGTON, D.C. 30666-0001

\*****/ March 24th l

Mr. William T. Cottle l

Executive Vice-President &

General Manager, Nuclear Houstoc Lighting & Power Company South Texas Project Electric Generating Station -

P. O. Box 289 Wadsworth, TX 77483

SUBJECT:

BULLETIN 88-08, " THERMAL STRESSES IN PIPING CONNECTED TO REACTOR COOLANT SYSTEMS," SOUTH TEXAS PROJECT, UNITS 1 AND 2 (STP) (TAC NOS.  :

M93822 AND M93823) l

Dear Mr. Cottle:

l

REFERENCES:

1. Letter of February 23, 1996, from T. W. Alexion, NRC, to W. T. Cottle, Houston Lighting and Power Company. l

2. WCAP-12598, Supplement 1, "NRC Bulletin 88-08, Evaluation of Auxiliary Piping for South Texas Project l Units 1 and 2," Westinghouse Electric Corporation (W),  !

November 1993. j i

3. EPRI TR-103581, " Thermal Stratification, Cycling, and Striping (TASCS)," prepared by Westinghouse Electric Corporation for the Electric Power Research Institute, ,

(EPRI) Palo Alto, California, March 1994. (Licensable l material, proprietary and confidential). l

4. Letter of July 15, 1996, from S. E. Thomas, Houston Light and Power (HL&P), to the USNRC Document Room, with attached W 1etter of June 19, 1996, from M. A.  ;

Sinwell, M, to W. T. Cottle, HL&P, with enclosure j

" Response to NRC Safety Evaluation of WCAP-12598, '

Supplement 1, and EPRI Report TR-103581."

5. Letter of October 29, 1996, from S. E. Thomas, HL&P, to the USNRC Document Control Desk.

, 6. Letter of April 11, 1994, from L. E. Kokajko, NRC, to W. T. Cottle, HL&P.

, In Reference 1, the NRC provided a safety evaluation (SE) of the revised

response by HL&P to NRC Bulletin 88-08. This response was authored by M as a contractor to HL&P (Reference 2). W based its response on an analytical methodology developed under a program sponsored by EPRI to investigate TASCS j (Reference 3). In Reference 4, HL&P submitted the W response to the SE in Reference 1.

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9703270238 970324 g DR ADOCK 0500 8  ;

1 1

. i Mr. William T. Cottle i

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L l l l

$ The NRC staff has reviewed the enclosure in Reference 4 and has concluded,  !

I based on the attached SE, that HL&P has not provided any new or additional  !

j information to supplement the information presented in Reference 3. The staff  :

j therefore, concludes that the concerns and conclusions stated in Reference 1  !

regarding the TASCS methodology have not been acceptably addressed, and are  !

i also applicable to the response in Reference. 4. The conclusions stated in  !

{ Reference I remain valid, namely-  !

! 1. The mechanism of turbulent penetration was not fully investigated under  !

I the TASCS program. Its relevance to the fatigue failures described in i

Bulletin 88-08 has not been clearly established. i t

i 2. The TASCS methodology does not address the observed fatigue failures l described in Bulletin 88-08. The thermal loading conditions for the j j failures described in Bulletin 88-08 remain undetermined.  ;

The staff also concludes that some elements of the TASCS methodology are i acceptable for application to the normal charging and the alternate charging

] lines at South Texas Units 1 and 2, provided HL&P commits to the following i provisions:

1

! 1. The thermal stresses due to isolation valve leakage are based on

temperature distributions determined from transient heat transfer l . calculations using the largest temperature difference between the

turbulence source and in-leakage- or out-leakage in the unisolable n sections. The temperature cyclic history should be such as to provide l the greatest stress range.

i i 2. Fatigue failure is postulated at the nearest weld to the turbulence i source in the case of a horizontal branch line attached to the reactor j coolant loop (RCL), or at the first elbow in a branch line with a i vertical segment attached to the RCL.

I 3. The American Society of Mechanical Engineers (ASME)Section III Class 1 j fatigue analysis is based on the rigorous combination of design basis

! transients and the thermal stresses due to isolation valve leakage.

4. The time interval from start of check valve leakage to crack initiation 3

is based on the ASME Section III, Class 1 fatigue analysis and a cycling  ;

! frequency of one cycle per minute is assumed, as recommended in i

Reference 3. l 4

{ 5. Monitoring provisions to determine inadvertent internal leakage through l j- the isolation valve are established and implemented. If such leakage is

- detected, the time interval determined in , step 4 establishes the allowable time interval to implement repairs.

i j In Reference 4, HL&P. indicated that the NRC position regarding'the auxiliary pressurizer spray lines and the residual heat removal lines was not clear.

j - The NRC position regarding these lines is the same as for the normal charging 1

n ,- -,-w-,

o l Mr. William T. Cottle March 24,1997 l

l l and the alternate charging lines stated above. Also, in Reference 5, HL&P i concluded that in NRC's April 11, 1994, lettr to HL&P (Reference 6), NRC's l statement that "the evaluation showed the fatigue adequacy of these lines to be on the order of ten years," should be interpreted to mean 10 years of operation at Normal Operating Temperature and Normal Operating Pressure, when the systems are potentially susceptible to stratification. The staff agrees with HL&P's interpretation.

In Reference 5, HL&P also requested a meeting with the staff to resolve any open NRC concerns and close this issue. The staff's position is that such a meeting would be constructive only if HL&P provides substantially new or different information.

Sincerely, orig. signed by Thomas W. Alexion, Project Manager Project Directorate IV-1 Division of Reactor Projects III/IV Office of Nuclear Reactor Regulation Docket Nos. 50-498 and 50-499 Eenclosure: As stated cc w/ encl: See next page DISTRIBUTION:

Docket File PUBLIC PD4-1 r/f JRoe EAdensam (EGAl) WBeckner CHawes TAlexion 0GC ACRS AHowell, RIV THarris,TLH3 Document Name: STP93822.LTR OFC PM/P_ -LA/PD4-1 NAME TAlexion/N CHawes(h]//

DATE bh/97

/ 3/2f/97 COPY kEh0 YES/NO L/ OFFICIAL RECORD COPY

Mr. William T. Cottle l and the alternate charging lines stated above. Also, in Reference 5, HL&P concluded that in NRC's April 11, 1994, letter to HL&P (Reference 6), NRC's statement that "the evaluation showed the fatigue adequacy of these lines to be on the order of ten years," should be interpreted to mean 10 years of operation at Normal Operating Temperature and Normal Operating Pressure, when the systems are potentially susceptible to stratification. The staff agrees with HL&P's interpretation.

In Reference 5, HL&P also requested a meeting with the staff to resolve any open NRC concerns and close this issue. The staff's position is that such a meeting would be constructive only if HL&P provides substantially new or different information.

Sincerely, ew /. h*o Thomas W. Alexion, Projec Manager Project Directorate IV-1 Division of Reactor Projects III/IV Office of Nuclear Reactor Regulation Docket Nos. 50-498 and 50-499 Eenclosure: As stated cc w/ enc 1: See next page i

i l

t 1 Mr. Williaa T. Cottle

Houston Lighting & Power Company South Texas, Units 1 & 2 I

cc:

Mr. David P. Loveless Jack R. Newman, Esq.

Senior Resident Inspector Morgan, Lewis & Bockius

! U.S. Nuclear Regulatory Commission 1800 M Street, N.W.

) P. O. Box 910 Washington, DC 20036-5869 d

Bay City, TX 77414 Mr. Lawrence E. Martin Mr. J. C. Lanier/M. B. Lee General Manager, Nuclear Assurance Licensing City of Austin Houston Lighting and Power Company Electric Utility Department P. O. Box 289 721 Barton Springs Road Wadsworth, TX 77483 Austin, TX 78704 Rufus S. Scott Mr. M. T. Hardt Associate General Counsel Mr. W. C. Gunst Houston Lighting and Power Company City Public Service Board P. O. Box 61867 P. O. Box 1771 Houston, TX 77208 San Antonio, TX 78296 Joseph R. Egan, Esq.

Mr. G. E. Vaughn/C. A. Johnson Egan & Associates, P.C.

Central Power and Light Company 2300 N Street, N.W.

P. O. Box 289 Washington, DC 20037 l Mail Code: N5012 Wadsworth, TX 74483 Office of the Governor ATTN: Andy Barrett, Director INP0 Environmental Policy Records Center P. O. Box 12428 700 Galleria Parkway Austin, TX 78711 Atlanta, GA 30339-3064 Arthur C. Tate, Director Regional Administrator, Region IV Division of Compliance & Inspection U.S. Nuclear Regulatory Commission Bureau of Radiation Control 611 Ryan Plaza Drive, Suite 400 Texas Department of Health Arlington, TX 76011 1100 West 49th Street Austin, TX 78756 Dr. Bertram Wolfe 15453 Via Vaquero Texas Public Utility Commission Monte Sereno, CA 95030 ATTN: Mr. Glenn W. Dishong 7800 Shoal Creek Blvd.

Judge, Matagorda County Suite 400N Matagorda County Courthouse Austin, TX 78757-1024 1700 Seventh Street Bay City, TX 77414 J. W. Beck Little Harbor Consultants, Inc.

44 Nichols Road Cohasset, MA 02025-1166