ML20140B734

Clarifies 851024 Response to NRC Request for Study of Jet Impingement Effects in Break Exclusion Area of Main Steam & Feedwater Piping.Encl NRC & Safety Evaluation Cited to Support Claim That Study Lacks Justification

ML20140B734
Person / Time
Site:	South Texas
Issue date:	01/20/1986
From:	Wisenburg M HOUSTON LIGHTING & POWER CO.
To:	Noonan V Office of Nuclear Reactor Regulation
Shared Package
ML20140B735	List: ML20140B760 ML20140B799 ST-HL-AE-1582, Clarifies 851024 Response to NRC Request for Study of Jet Impingement Effects in Break Exclusion Area of Main Steam & Feedwater Piping.Encl NRC & Safety Evaluation Cited to Support Claim That Study Lacks Justification
References
CON-#186-816, RTR-NUREG-0800, RTR-NUREG-800 OL, ST-HL-AE-1582, NUDOCS 8601270114
Download: ML20140B734 (3)

Text

p. ~ q The Light Company n-i- us,w- im>x im n-u.nmxas mm mmmen January 20, 1986 ST-hl-AE-1582 File No.: G9.17, N3.8.10 Mr. Vincent S. Noonan, Project Director PWR Project Directorate #5 U. S. Nuclear Regulatory Commission Washington, CC 20555 South Texas Project Units 1 and 2 Docket Nos. STN 50-498, STN 50-499 Clarification of STP Position Regarding Break Exclusion Zone Design Basis

Reference:

Letter ST-HL-AE-1436, dated 10/24/85, M. R. Wisenburg to G. W. Knighton

Dear Mr. Noonan:

The intent of this letter is to clarify HL&P's position regarding recent requests from NRC reviewers to perform an evaluation of the effects of jet impingement in the break exclusion area of the main steali and feedwater piping. The NRC's request is based on Branch Technical ?osition (BTP) ASB 3-1 (contained in NUREG 0800, dated July, 1981). However,.since STP conforms to the requirements of NUREG 75/087, Section 3.6, (the licensing basis for STP) the requested evaluation is beyond the STP licensing basf.s and is therefore considered a backfit.

In response to initial NRC requests on this subject, the feasibility of performing the additional jet impingement evaluation was investigated.

Although HL&P has a high degree of confidence that such an evaluation would be successful, our investigation has shown that the effort required would be significant. We further believe that such an evaluation is unnecessary, As stated in FSAR Table 3.6.1-2, entitled " Design Comparison to ASB 3-1,"

the Isolation Valve Cubicle (IVC) and essential equipment is designed to the environmental and pressurization effects of a single area circumferential l

break. No breaks are postulated in break exclusion piping in the area of the torsional and bending restraints. The justification for this design basis is as follows:

o The criteria for the design of break exclusion zone piping was established prior to the issuance of NUREG 0800 in 1981. The STP criteria (delineated in FSAR Sections 3.6.1 and 3.6.2, and the reference letter) conforms to the requirements of BTP APCSB 3-1

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ST-HL-AE-1582 File No.: G9.17, N3.8.10 Page 2 Houston Lighting & Power Company (contained in NUREG 75/087). The STP position regarding paragraph B.l.a (1) of BTP ASB 3-1 is documented in FSAR Section 3.6.2.1.1 (5) and in FSAR Table 3.6.1-2. The NRC previously issued a Safety

, Evaluation Report (see attachment) on the subject of dynamic effects of postulated pipe whip failures outside of containment. This document confirmed the acceptability of designing the main steam and feedwater isolation valve rooms (in the IVC) for the environmental and subcompartment pressurization effects of a single area break with no stipulations regarding consideration of jet impingement effects.

o In several cases, the staff has granted relief from the requirement to postulate arbitrary intermediate breaks in piping which is not part of a break exclusion zone. In light of the NRC's safety evaluations supporting these actions, the requirement to evaluate jet impingement effects for breaks in the break exclusion portions of the main steam and feedwater piping has no technical justification.

In summary, the STP design basis regarding pipe breaks in the break exclusion piping in the main steam and feedwater isolation valve rooms (in the IVC) is as follows: Essential equipment is designed to be protected from or qualified to the environmental effects resulting from a full circumferential break (single area) in the main steam or main feedwater piping. Essential equipment is also designed to be protected from the jet impingement and pipe whip effects resulting from a full circumferential break postulated in the~

branch piping associated with the main steam or main feedwater piping.

If you should have any questions on this matter, please contact 4 Mr. M. E. Powell at (713) 993-1328.

Very trul yours, xi M. R. Wi nburg Manager, clear cen ng DMC/yd

Attachment:

Letter from Olan Parr to G. W. Oprea, dated 6/6/77.

Ll/NRC/je

l ST-HL-AE-1582 File No.: G9.17 Houston Lighting & Power Company Page 3 cc:

Hugh L. Thompson, Jr., Director Brian E. Berwick, Esquire Division of PWR Licensing - A Assistant Attorney General for Office of Nuclear Reactor Regulation the State of Texas i U.S. Nuclear Regulatory Commission P.O. Box 12548, Capitol Station 1

Washington, DC 20555 Austin, TX 78711 Robert D. Martin Lanny A. Sinkin Regional Administrator, Region IV Christic Institute Nuclear Regulatory Commission 1324 North Capitol Street

611 Ryan Plaza Drive, Suite 1000 Washington, D.C. 20002 Arlington, TX 76011 Oreste R. Pirfo, Esquire N. Prasad Kadambi, Project Manager Hearing Attorney U.S. Nuclear Regulatory Commission Office of the Executive Legal Director 7920 Norfolk Avenue U.S. Nuclear Regulatory Commission Bethesda, MD 20814 Washington, DC 20555 Claude E. Johnson Charles Bechhoefer, Esquire j Senior Resident Inspector /STP Chairman, Atomic Safety &

, c/o U.S. Nuclear Regulatory Licensing Board Commission U.S. Nuclear Regulatory Commission P.O. Box 910 Washington, DC 20555 Bay City, TX 77414 Dr. James C. Lamb, III M.D. Schwarz, Jr., Esquire 313 Woodhaven Road Baker & Botts Chapel Hill, NC 27514

! One Shell Plaza Houston, TX 77002 Judge Frederick J. Shnn Atomic Safety and Licensing Board J.R. Newman, Esquire U.S. Nuclear Regulatory Commission Newman & Holtzinger, P.C. Washington, DC 20555 1615 L Street, N.W.

3 Washington, DC 20036 Mr. Ray Goldstein, Esquire 1001 Vaughn Building Director, Office of Inspection 807 Brazos and Enforcement Austin, TX 78701 U.S. Nuclear Regulatory Commission Washington, DC 20555 Citizens for Equitable Utilities, Inc.

c/o Ms. Peggy Buchorn T.V. Shockley/R.L. Range Route 1, Box 1684 Central Power & Light Company Brazoria, TX 77422 P.O. Box 2121 Corpus Christi, TX 78403 Docketing & Service Section i

Office of the Secretary H.L. Peterson/G. Pokorny U.S. Nuclear Regulatory Commission City of ' Austin Washington, DC 20555 P.O. Box 1088 (3 Copies)

Austin, IX 78767 Advisory Committee on Reactor Safeguards J.B. Poston/A. vonRosenberg U.S. Nuclear Regulatory Conunission

! City Public Service Board 1717 H Street P.O. Box 1771 Washington, DC 20555 San Antonio, TX 78296

Revised 12/3/83 Ll/NRC/je

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