ML17278B174

Requests Approval to Apply ASME Code Case N411 on Facility, to Enhance Sys Reliability & Personnel Safety Through Optimization of Snubber Installations.Fee Paid

ML17278B174
Person / Time
Site:	Columbia
Issue date:	01/21/1987
From:	Sorensen G WASHINGTON PUBLIC POWER SUPPLY SYSTEM
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
GO2-87-026, GO2-87-26, TAC-64595, NUDOCS 8702020404
Download: ML17278B174 (13)

Text

REQ TOR NFORN*TION DISTR IBU N TEl'1 (R IDS)

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g il ACCESSION NBR: 8702020404 DOC. DATE: 87/Oi /21 NOTARIZED: NO DOCKET 0 FAC I L: 50-397 MPPSS Nuclear Progecti Unit 2i Mashington Public Poue 05000397 AUTH. NAI 1E AUTHOR AFFILIATION SORENSEN Q. C. Mashington Public Power Supply Sgstem.

REC IP. NANE RECIPXENT AFFILIATION Document Control Branch (Document'ontrol Des k )

SUBJECT:

Requests approval to apply ASNE Code Case N411 on facility>

to enhance sos reliability 8r personnel safety through optimi zation aP snubber insta1 lat i ons. Fee paid.

DXSTRIBUTION CODE: A047D COPIES RECEIVED: LTR Q ENCL 0 SI ZE:

TITLE: OR. Submittal: Inservice Inspection/Testing NOTES:

RECIPXENT COPIES RECIPIENT COPIES ID CODE/NANE LTTR ENCL ID CODE/NAME LTTR ENCL BMR ADTS BMR EB BMR PD3 LA BWR PD3 PD Oi BRADFUTEi J INTERNAL: ACRS 16 io 1 ADN/LFNB AEOD/PTB i ELD/HDS2 S /EIB i NRR/TANB REQ F E -04 EXTERNAL: LPDR 03 NRC PDR 02, NSIC 05 00 p O"ll~

TOTAL NUMBER OF COPIES REQUIRED: LTTR 28 ENCL 6

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Washington Public Power Supply System P.O. Box 968 3000 George Washington Way Richland, Washington 99352 (509) 372-5000 87oaozo4o4 8>o>>

January 21, 1987

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Docket No. 50-397 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D.C. 20555 Gentlemen:

Subject:

NUCLEAR PLANT NO. 2 RE/VEST FOR ASME CODE CASE N411 APPROVAL

Reference:

Letter, T. M. Novak (NRC) to D. W. Mazur (SS),

"Approval of ASME Code Case N411 - Washington Nuclear Project No. 1", Docket No. 50-460, dated August 22, 1985 The reference letter documents the NRC's approval to apply ASME Code Case N411 at the Supply System's WNP-1 project. The purpose of this letter is to request approval to apply this code case on WNP-2.

The Supply System is vitally interested in enhancing system reliability and personnel safety through optimization of snubber installations at all of its projects. However, at this time there is no intent to implement a large scale snubber optimization program at WNP-2. In the near term it is believed that a slower-paced program is prudent. This position has been adopted in light of the several key issues important to the overall effectiveness of a snubber optimization effort that currently remain under industry and Staff advisement as to their overall licensing acceptability. For example, the application of independent support motion techniques with N411 damping and guidance on the broad scope leak-before-break ruling could have significant impact on the effectiveness of a snubber optimization effort.

As stated, approval is requested to incorporate into the licensing basis, and apply, Code Case N411 damping at WNP-2. At WNP-2 the N411 Code Case damping values would be applied as the need arises under the following circumstances:

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~ yp Page Two RE(VEST FOR ASNE CODE CASE N411 APPROVAL When existing WNP-2 piping is re-analyzed for system modification or repair.

2. When new piping systems are added to the plant.

3. Where the plant staff has identified snubbers which pose a significant in-service inspection man-rem exposure burden.

Code Case N411 will be applied in full compliance with all five requirements delineated in the current revision of USNRC Regulatory Guide 1.84. In brief, review of these requirements is as follows:

The code case damping values shall only be applied to piping analyses and only in those dynamic load cases in which the loads are building filtered with a frequency content not exceeding 33 Hertz. In those analysis load cases where Code Case N411 is applied, Regulatory Guide 1.61 damping values shall not be combined with the code case damping values.

2. The code case damping values shall only be applied in response spectrum analyses utilizing the "enveloped" or uniform support motion technique per NUREG/CR-3526. The spectrum envelopes at WNP-2 are founded on the general requirements of Regulatory Guide 1.60 and the resultant load reactions shall be generated from all three components of earthquake motion and applied concurrently to support structures.

3. As a result of possible increased dynamic deflections, optimized piping systems shall be physically walked down prior to snubber removal to ensure that sufficient clearances exist to preclude interferences with stationary and line mounted equipment.

The code case shall not be used in piping systems which utilize plastic strain energy absorption devices.

5. The code case shall not be applied to piping systems where stress corrosion cracking has occurred. WNP-2 has completed an extensive induction heating stress improvement program and, in addition, stress corrosion cracking resistant materials have been installed in critical locations. The plant is also implementing system improvements to attain water chemistry quality standards consistent with the BWR Water Chemistry Guidelines. At present no case of stress corrosion cracking has been identified and because of the efforts to mitigate this phenomenon at WNP-2, there is no intent to restrict the application of the code case on this basis (i.e., stress corrosion cracking).

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Page Three REQUEST FOR ASME CODE CASE N411 APPROVAL The original design basis for WNP-2 required that responses due to inertial loads be combined with pseudostatic responses (e.g., seismic anchor motions) by the absolute sum method (NUREG-0892, WNP-2 Safety Evaluation Report, pg. 3-16, Paragraph 3. 7. 3, dated March 1982). Based on the recommendations of NUREG-1061, Volume 4, approval to utilize the square-root-sum-of-squares methodology for the combination of inertial and pseudostatic loads is requested. This methodology would be applied in analyses utilizing the code case damping values. No other change or deviation from the current WNP-2 licensed piping and pipe support design methodology would be applied.

An additional action WNP-2 will implement, independent of any revision to the current licensing basis, is the selective (i.e., prioritized) replacement of snubbers which have thermal movements meeting the displacement criteria established by Welding Research Counci 1 Bulletin 300. These snubbers will be replaced with equivalent strength rigid struts. A review of the WNP-2 analysis bases is currently in progress to identify the candidate population of "zero" movement snubbers. It should be noted that the results of WNP-2's Power Ascension Test Program showed excellent agreement between measured piping system thermal movements and analytically predicted thermal expansion move-ments. This provides an experimental basis which lends confidence to the analytic evaluation of zero thermal movement snubbers.

Following Staff approval to implement the code case, the WNP-2 Final Safety Analysis Report (FSAR) wi 11 be amended to document the specific requirements and conditions under which the N411 Code Case can be applied. The Supply System will periodically revisit its licensing basis as the industry and Staff'ositions evolve and solidify on improved analysis techniques for snubber optimization.

It is rei terated that the Supply System is presently subscribing to a cautious snubber optimization effort at WNP-2 that is primarily focused on critical need areas. Minimal and conservative licensing basis changes are proposed that are in close harmony with the Staff's current posi tion on advanced analysis techniques for snubber optimization. Albeit conservative, the requested piping analysis changes will afford the Supply System an opportunity to work towards enhanced reliability and improved ALARA performance.

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Page Four REQUEST FOR ASME CODE CASE N411 APPROVAL To assist the Supply System in attaining the WNP-2 interim snubber optimization program goals, a timely response to this request is sought. WNP-2's Spring outage is the first opportunity to realize the safety and economic benefits that can be attained through the reduction of redundant snubbers. Therefore, Staff action on this request by early March would be greatly appreciated.

In accordance with 10CFR 170.12(c), an application fee of One hundred fifty dollars ($ 150.00) is enclosed.

Should you have any questions, please contact Hr. P. L. Powell, Manager, WNP-2 Licensing.

Very truly yours, G. C. So ensen, Manager Regulatory Programs JRC/DMB/tmh Attachment cc: JO Bradfute - NRC JB Hartin - NRC RV E Revell - BPA NS Reynolds - BLCP8R NRC Site Inspector

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January 16, 1987 DISTRIBUTION: W/0 Encl osures DOCKET NO(S). 50-397 =, MDocket No. 50-397 BWD-3 r/f Hr. G. C. Sorensen, Manager EHyl ton (2)

>cwashington Public Power Supply System JBradfute P; 0. Box 968 3000 George Washington Way Richland, washington 99352

SUBJECT:

WNP-2 55 r The following documents concerning our review of the subject facility are transmitted for your information.

D Notice of Receipt of Application, dated D Draft/Final Environmental Statment, dated D Notice of Availability of Draft/Final Environmental Statement, dated D Safety Evaluation Report, or Supplement No. , dated D Notice of Hearing on Application for Construction Permit, dated D Notice of Consideration of Issuance of Facility Operating License, dated Bi-Meekly Ijg Qgp+yxNotice; Applications and Amendments to Operating Licenses Involving no Significant Hazards Considerations, dated b (See page 47088).

D Application and Safety Analysis Report, Volume D Amendment No. to Application/SA R dated D Construction Permit No. CPPR- , Amendment No. dated D Facility Operating License No. , Amendment No. , dated D Order Extending Construction Completion Date, dated D Other (Specify)

Office of Nuclear Reactor Regulation

Enclosures:

As stated cc: See next page OFF>CK~ LA'D L SURMAMK~EH p(yag DATE~ 1/C(P /87 NRC FORM 318 t1/84) NRCM 0240

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Mr. G. C. Sorensen, Manager WPPSS Nuclear Proiect No. 2 Washington Public Power Supply System (WNP-?i CC:

Nicholas S. Reynolds, Esq. Regional Administrator, Region V Bishop, Liberman, Cook, U.S. Nuclear Regulatory Commission Purcell 5 Reynolds 1450 Maria Lane, Suite 210 1?00 Seventeenth Street, N.W. Walnut Creek, California 94596 Washington, D.C. 20036 Nr. G. E. Doupe, Esquire Washington Public Power Supply System P. 0. Box 968 3000 George Washinoton Way Richland, Washington 99532 Mr. Curtis Fschels, Chairman Energy Facility Site Evaluation Council Nail Stop PY-ll Olympia, Washington 98504 P. L. Powell, Licensing Manager Washington Public Power Supply System P. 0. Box 968, MD 956B Richland, Washington 99352 Mr. W. G. Conn Burns and Roe, Incorporated c/o Washington Public Power Supply System P. 0. Box 968, ND 994F.

Richland, Washington 99352 R, B. Glasscock, Director Licensing and Assurance Washington Public Power Supply System P. 0. Box 968, ND 280 Richland, Washington 99352 Mr. C. M. Powers WNP-2 Plant Manager Washington Public Power Supply System P. 0. Box MD 927M Richland, Washington 99352