ML20206K292

Forwards Request for Addl Info Re Elimination of Postulated Accumulator Line Ruptures as Design Bases.Justification for for Using thermally-aged Cast Stainless Steel in WCAP-10456 for Limiting Welds Requested

ML20206K292
Person / Time
Site:	South Texas
Issue date:	04/14/1987
From:	Kadambi N Office of Nuclear Reactor Regulation
To:	Goldberg J HOUSTON LIGHTING & POWER CO.
References
NUDOCS 8704160318
Download: ML20206K292 (6)

Text

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April 15o 1987 Docket Nos. 50-498 and 50-499 ,

Mr. J. H. Goldberg Group Vice President, Nuclear Houston Lighting & Power P.O. Box 1700 Houston, Texas 77001

SUBJECT:

REQUEST FOR ADDITIONAL INFORMATION RELATIVE TO THE GDC-4 EXEMPTION REQUEST ON THE ACCUMULATOR LINE The staff transmitted to you on March 27, 1987 a. request for additional information on the exemption request related to the Pressurizer Surge Line.

Enclosed is a similar recuest related to the Accumulator Line based on the submittals WCAP-11383 anc WCAP-11351.

Please inform us as to your schedule for providing the responses. Please contact me at (301) 492-7272 if you have any questions.

Sincerely, Is/

j N. Prasad Kadambi, Project Manager ProjectDirectorateNo.4 i

DivisionofReactorProjects-III, IV, V'and Special Projects

Enclosure:

j As stated i

cc: See next page I

_ DISTRIBUTION _

Docket E11e 4 B. Grimes NRC PDR J. Partlow Local PDR J. Calvo PD-4 Reading P. Kadambi D. Crutchfield P. Noonan 0GC ACRS (10)

E. Jordan Tech Branch tht had input in package South Texas File k(?U PD-4 PD-4:Dyf NPKadambi:sr JACalvo 4/IQ87 4

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0704160318 870414 PDR ADOCK 05000498 A PDR

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Mr. J. H. Goldberg Houston Lighting and Power Company South Texas Project cc:

Brian Berwick, Esq. Resident Inspector / South Texas Assistant Attorney General Project Environmental Protection Division c/o U.S. Nuclear Regulatory Commission P. O. Box 12548 P. O. Box 910 Capitol Station Bay City, Texas 77414 Austin, Texas 78711 Mr. Jonathan Davis Mr. J. T. Westermeir Assistant City Attorney Manager, South Texas Project City of Austin Houston Lighting and Power Company P. O. Box 1088 P. O. Box 1700 Austin, Texas 78767 Houston, Texas 77001 Ms. Pat Coy Mr. H. L. Peterson Citizens Concerned About Nuclear Mr. G. Pokorny Power City of Austin 5106 Casa Oro P. O. Box 1088 San Antonio, Texas 78233 Austin, Texas 78767 Mr. Mark R. Wisenberg Mr. J. B. Poston Manager, Nuclear Licensing Mr. A. Von Rosenberg Houston Lightirp and Power Company City Public Service Boad P. O. Box 1700 P. O. Box 1771 Houston, Texas 77001 San Antonio, Texas 78296 Mr. Charles Halligan Jack R. Newman, Esq. Mr. Burton L. Lex Newman & Holtzinger, P.C. Bechtel Corporation 1615 L Street, NW P. O. Box 2166 Washington, D.C. 20036 Houston, Texas 77001 Melbert Schwartz, Jr., Esq. Mr. E. R. Brooks Baker & Botts Mr. R. L. Range One Shell Plaza Central Power and Light Company Houston, Texas 77002 P. O. Box 2122 Corpus Christi, Texas 78403 Mrs. Peggy Buchorn Executive Director Citizens for Equitable Utilities, Inc.

Route 1, Box 1684 Brazoria, Texas 77422

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l Houston Lighting & Power Company South Texas Project cc:

Regional Administrator, Region IV U.S. Nuclear Regulatory Commission Office of Executive Director for Operations 611 Ryan Plaza Drive, Suite 1000 Arlington, Texas 76011 Mr. Lanny Sinkin, Counsel for Intervenor Citizens Concerned about Nuclear Power, Inc.

Christic Institute 1324 North Capitol Street Washington, D.C. 20002 Licensing Representative Houston Lighting and Power Company Suite 1309 7910 Woodmont Avenue Bethesda, Maryland 20814 F

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• e FNCLOSURE REQtlEST FOR ADDITIONAL INFORMATION ON ELIMINATION OF POSTULATED ACCUMULATOR LINE RUPTURES AS A DESIGN BASIS HOUSTON LIGHTING & POWER COMPANY S0llTH TEXAS PROJECT UNITS 1 AND 2 DOCKET NOS. 50-498 A 50-499 i

I (1) Provide material specification and all fracture toughness properties of '

, the accumulator tank and its nozzle (and any safe end and associated weld). If the material is ferritic, determine whether the material is at the upper shelf of the fracture eneray at the operating temperature, and compare the fracture properties to those of the weld. Justify why welds at valves are not limiting. Provide a sketch of the cross-section of the valve-to-pipe weld at limiting location 284 on Figure 5-2 of WCAP-11351.

(2) Describe the process of fabrication of the limiting welds. Provide justification for using the thermally-aged cast stainless steel in WCAP-10456 for the limiting welds. Specifically, compare the base metal, weld metal, and welding process parameters between the limiting welds and '

the welds considered in WCAP-10456.

(3) The Code minimum yield and ultimate strengths of SA376 TP316 are used for the base metal. However, from Table 4-6 in WCAP-11351, other materials in the accumulator line, i.e., SA312 TP304L, SA403 WP316L, and SA182 F316L have lower Code minimum yield and ultimate strengths. If the intent is to use the lower bound material properties, justify;the selection'of SA376 TP316 as the limiting material.

(4) The portions of the accumglator ling considered in WCAP-11383 and WCAP-11351 operate at 560 F and 120 F, respectively. Provide the moduli and the stress-strain relationships of the ligiting matgrial(s) at the appropriate operating temperatures, i.e., 560 F and 120 F.

(5) In order to complete our safety evaluation, the staff needs to evaluate the~ accumulator ifne for potential degradation during service. Therefore, the applicant should provide a discussion on the potential and preventive measure for vibratory fatigue (socket welds, if any), flow stratification '

(and associated low cycle thennal fatiguel, wall thinning by erosion, and creep. Also, discuss the experience of the accumulator lines of Westinghouse design with respect to in-service cracking.

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(6) A generic fatigue crack growth analysis was perfomed for the accumulator line. If the sequence of transients in the fatigue crack growth analysis was not selected randomly, provide the specific secuence used in the analysis. Fifteen transients were considered in the fatigue analysis with no Operating Basis Earthquake (ORE). Since the staff considers it appropriate to include the OBE, justify this exclusion.

(7) Because of a lower fluid temperature, the leak rate prediction in 1

WCAP-11351 used a model different from that benchmarked in WCAP-11256 (Supplement 1). Provide a benchmark for the leak rate prediction model against leak test data at the appropriate fluid temperature.

(8) Relative to the system (si that would be relied upon in this application, provide discussion of the leakage detection system (s) and procedures for detection and operator action at South Texas. Justify the workability of these systems and procedures in terms of operating experience at Westinghouse plants. Describe the background unidentified average leakage rate expected at South Texas and the basis for this prediction.

Justify the use of 0.5 gpm as the minimum detectable unidentified leakage. Discuss the Technical Specification and/or administrative procedure requirements for locating a 0.5 gpm unidentified leakage. Also discuss repair and system limiting conditions for operation associated with a leak in the accumulator line. Clarify if the entire accumulator line is reactor coolant pressure boundary piping. Also, clarify if a leaking pipe in the leak-before-break scope will be declared inoperable.

(91 In order to complete our safety evaluation, the staff needs to evaluate

! the potential of pipe degradation or failure from indirect causes such as fire, missiles, and component support failure as prevented by design, fabrication, and inspection. Therefore, the applicant should for i completeness provide a discussion on the compliance with Standard Review Plan 3.4.1, 3.5.1.2, 3.9.3, 3.9.6, and 9.5.1.  ;

(10) It appears that a lower-bound stress-strain relationship was used in estimating the crack-opening area and thus, the leakage rate. The staff 1 considers it more appropriate to use the average stress-strain j relationship in estimating leakage rates. Provide justification that a lower-bound stress-strain relationship gives a conservative estimate of 3

the leakage rate.-

(11) WCAP-11383 deals with the Class 1 portion of the accumulator line from the Reactor Coolant System (RCSI cold leg in.iection points to the first check valve, and WCAP-11351 deals with the Class 1 portion of the accumulator line operating at 1200F. Provide clarification that the i

entire accumulator line, from anchor to anchor, has been considered in 1 the leak-before-break analysis as required by NUREG-1061, Volume 3. If the line contains other than Class 1 piping, the other piping Classes should be considered in the LRB analysis also. Clarify if the line I

between the accumulator tank and the check valve is Class 2. With t i i

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e reference to Figures 5-1 throuch 5-3 in WCAP-11351, clarify if the branch piping is Residual Heat Removal (RHR) piping. Also clarify if there is any low energy line in the piping, from anchor to anchor.

(12) Linear elastic fracture mechanics was used for the fracture stability analysis. However, from the calculated ".1 " it appears that the associated Irwin plastic zone sizes are notDEma,ll compared with the half-crack length "a". The staff considers it appropriate to use elastic-plastic fracture mechanics. In fact, the applicant used elastic-plastic fracture mechanics in the surge line analysis in WCAP-10489 where the "J " and crack sizes are similar to those for the accumulator line. Just19) the use of linear elastic fracture mechanics for the accumulator line or perform a reanalysis using elastic-plastic fracture mechanics.

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