ML17037C484

Letter Regarding a Report on Pipe Failures Outside of Containment and an Enclosed Safety Evaluation - Analysis of the Consequences of High Energy Piping Failures Outside Containment

ML17037C484
Person / Time
Site:	Nine Mile Point
Issue date:	06/11/1974
From:	Goller K US Atomic Energy Commission (AEC)
To:	Raymond P Niagara Mohawk Power Corp
References
Download: ML17037C484 (16)

Text

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'UN l11S74 Branch Reading JRBuchanan, ORNL Docket Ho. 50-220 TJCarter, L:OR ACRS (16)

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OGC DLZiemann, L:ORB I/2 CJDeBevec, L:ORB 82 Niagara Mohawk Power Corporation JCSnell, L:ORB /l2 ATTN: Hr. Philip D. Raymond meiggs, L:ORB II2 Vice President Engineering SVarga, L:RP 300 Erie Boulevard Vest Syracuse, New York 13202 Gentlemen:

Your letter dated June 29, 1973, submitted a report on pipe failures outside of containment for Nine Mile Point Unit 1 (RiP-l) as required by our letter of December 18, 1972. Our letters of December 18, 1972, and January 16, 1973, contained criteria by which a postulated rupture in any high ene'rgy fluid piping outside the primary containment was to be evaluated to assure safe plant shutdown capabQ.ity. On January 30, 1973, a meeting was held to discuss the criteria and the results of your preliminary study of RiP-l.

Upon completion of our initial review of your report, further clarification of the analysis was requested in our letter of January 29, 1974., Your letter dated February 28 '974, responded to this request.

Based upon our review of your report,'s supplemented, we have concluded that Nine Mle Point Unit 1. would w'ithstand the consequences of postulated ruptures in high energy fluid piping outsidq containment without loss of capability to initiate and maintain safe shutdown of the plant. A, copy of our related Safety Evaluation is enclosed.

Sincere1y, Original si~neH by

<arl R. GoHer Karl R. GoU.er Assistant, Director for Operating Reactors Directorate of Licensing

Enclosure:

Safety Evaluation cc: See next page CRESS oFF>cE> L'0 82 L:ORB Ij2 L:0 //2 L'OR T11098(1-9) m lm suRNAMEg JC 1 DLZi ann 68&

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J Bruce -MacDonald, Esquire Deputy Commissioner and Counse1 New York State Department of Commerce and Counsel to the Atomic Energy Counci1 99 Washington Avenue Albany, New York 12210 Arvin E. Upton, Esquire LeBoeu f, Lamb, Leiby & MacRae 1757 N Street, N. H.

Washington, D. C~ 20036 Dr . Hilliam Seymour Staf f Coordinator New York State Atomic Energy Council New York State Department of Commerce 112 State Street Albany, New York 12207 Anthony Z. Ro isman, Esquire Berlin, Roisman and Kessler-1712 N Street, N. W.

Washington, D. C. 20036 Oswego County Library OFFICERS'URNAME+

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UNITED STATES ATOMIC ENERGY COKHSSXON SAFETY EVALUATION B THE D RECTORATE OF LICENSING DOCKET NO. 50-220 NXNE MILE POINT UNIT 1 ANALYSXS OR THE CONSEQUENCES OR HIGH ENERGY PIPING FAILURES OUTSIDE CONTAINKBiT INTRODUCTION On December 18, 1972, and January 16, 1973, the Atomic Energy Commission's Regulatory staff sent letters to Niagara Mohawk requesting a detailed analysis to 'substantiate that the design of the Nine Mile Point Unit 1 (NNP-1) is adequate to withstand the effects of a postulated rupture in any high energy fluid piping system outside the primary containment, including the postulated double-ended rupture of the largest line in the main steam and feedwater systems. Xt was further requested that if the results of the analysis indicated that changes in the design were necessary to assure safe plant shutdown, information on these design 'changes and plant modifications would be required. Criteria for conducting this evalu-ation were included in the letters. A meeting was held on January 30, 1973, to discuss the information already available on the NHP-1 design concerning postulated pipe ruptures, to clarify the applicable criteria, and to identify the areas where additional information was required.'n response, a report describing postulated high energy pipe ruptures outside containment was filed by Niagara Mohawk on June 29, 1973. A subsequent letter from Niagara Mohawk dated February 28, 1974, provided additional information in response to our letter dated January 29,'974.

EVALUATION Criteria A summary of the criteria and requirements that were used in our evaluation was included in our letter of December 18, 1972, and is set forth below:

a. Protection of equipment and structures necessary to shut down the reactor and maintain it in a safe shutdown condition, assuming a con-current .and unrelated single active failure of protected equipment, should be provided from all effects resulting from ruptures in pipes carrying high energy fluid, where the temperature and pressure condi-tions of the fluid exceed 200 F and 275 psig, respectively, up to and OFFICEI9 SURNAME+

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including a double-ended rupture of'uch pipes Breaks should be assumed to occur in locations specified in the "pipe whip criteria".

The rupture effects to be considered include pipe whip, structural (including the effects of )et impingement), and environmental, I

b. Tn addition, protection of equipment and structures necessary to shut down the reactor and maintain it in a safe shutdown condition, assuming a concurrent and unrelated single active failure of pro-tected equipment, should. be provided from the envix'onmental and structural effects (including the effects of get impingement) resulting from a single open cxack at the most adverse location in pipes carrying fluid routed Xn the vicinity of this equipment, The size of the cracks should be assumed to be 1/2 the pipe diameter in length and'/2 the wall thickness in width Hi h Ener S stems Our evaluation included the following piping systems containing high energy fluids:

tMin~ Extraction, and Auxiliary Steam Systems Peedwater System Core Spray System Condensate System Containment Spray System Emergency Condenser Liquid Poison System Reactor Head Spray System Reactor 'Vater Cleanup System {RWCU)

Reactor Shutdown Cooling System Sample Lines (Environmental Effects Only)

Areas or S stems Affected b Hi h Ener Pi e Breaks An evaluation was made of the effects of high energy'ipe breaks on the following systems, components, and structures which. would be necessary (in various combinations, depending on the effects of the break) to safely shut dmm, cool down~ and maintain cold shutdown conditions:

a. General

1. Contxol Room 2~ Contxol and Xnstrument Cables and Tunnels 3 Electrical Distribution System 4 Emergency dc Power Supply (batteries)

5. Emergency ac Power Supply (diesels) 6 Heating and Ventilation Systems (needed for long-term occupancy to maintain the reactor in safe shutdown condition)

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b. IIeactorgontrol systems and assoctated Instromentatdon

c. Cooling and FServicepfaterySystems d HCCS components S ecific Areas of Concern The applicant has provided the results of his examination of all postulated safety-related high energy line break locations and evaluated the break consequences. We have reviewed all of this information, including the following specific areas of concern where the potential consequences might be severe or where specific corrective action would further assure safe cold shutdown of the plant.

a. Com artment Pressurization Large pipe breaks~ includin the double-ended rupture of 'the largest pipes in a system, and sm leakage cracks up to the design basis size have been considere4 for the main steam tunnel, the turbine building, the ECCS rooms,'nd the valve compartments In the main steam tunnel~ the effects of a main steam line break were considered as the worst case. The resultant pressure was calculated to increase to a peak of 33.1 psia. The tunnel has a minimum design of 3I4 6 psia so that the calculated peak is below the design pressure~

thus assuring a margin A postulated high energy line failure in the reactor water cleanup system results in a single-ended piping failure until isolation is achieved. Safety related equipment would not be affected; therefore' safe shutdown of the plant could be accomplished.

b. ~1'1 e Wbl The steam tunnel has been designed with thick reinforced concrete capable of withstanding static and dynamic loads, The reinforced concrete steam tunnel in which the main steam and feedwater lines are routed from the primary containment to the turbine room is subjected only to the loads of the piping and a live load from the floor on top of the tunnel roof.

~alyses of pipe whip effects on concret arripys~dicate that local cracking of the barriers can oc > ~owevee, the structural integrity of the walls is maintained. t Cracks and access openings can allow steam to escape to other parts of the floor and building.

-OFFICED SURNAMED'ATED Form AECD18 (Rev. 9-53) AECM 0240 'A U.s. GovcRNMcNT PAIN'TING GFFIcc: ls7$ ~$ $ 2$ $

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alyses have- also sh that pip whip can cause column faQ ure in f

the area of the break~ Homever there is sufficient design margin in the other columns such that the structural integrity of the floors is maintained Other high energy systems, such, as the emergency condenser, 1 uid poison, and the core spray, have been evaluated,for whipping Afh1le a whipping line in some of these systems may cause failure of addi-tional systems or equipment, the incident mould. not prevent the safe shutdown of the unit.

+thar high energy lines, such as the sample Uses and reactor wnter cleanup lines, are located such that their rupture would not cause to the torus or prevent. redundant safety related equipment 'amage from functioning to allow the plant to be safely shut down.

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~o main control room is physically isolated from all high energy lin~es.)gfeither the control room equipmant nor its vent11ation system wDl be affected by environmental effects caused by a rupture of a high "energy line.

d Environmental Effects Components and. equipment were analyzed and checked for possible W .he adverse environmental effects which could be caused by the rupture od a high energy line. Adverse temperature, pressure, and humidity ware the psrametet's which vet'a used h, the eva1ua ion og safety related equipment f

djcansae~ssassmcut of ths consequences of environmental ef ects on safety related equipment ~.

He-Scend that safety related equipment has been designed to limits ixl Qzcess of postulated condit ions which could arise from the rupture of a high . ener gy 1 ine.

CONCLUSION On the basis of 'tMs review of the information submitted to us and based on our discussions with Niagara Mohawk, we find that the consequences of high energy line failures outside containment are acceptable. Ve have OFFICEW SURNAMEth DATE+

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concluded that the potential consequences of these postulated high energy pipe failures could not prevent achieving safe cold shutdown conditions consistent with the single failure and redundancy requirements described in our letter of December 18, 1972, and thus there is reasonable assurance that the health and safety of the public will not be endangered by continued operation in the manner proposed.

James C. Snell Operating Reactors Branch 02 Directorate of Licensing

'griglnal signed W Dennis L. Zk1nn>>

Dennis L. Ziemsnn, Chief Operating Reactors Branch Directorate of Licensing JUN 11 1974 OPPICC~

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'Di tribution JUN 5 1974 ocket File AEC PDR Local PDR Docket No. 50-220 Branch Reading JRBuchanan, ORNL TJCarter, L:OR ACRS (16)

Niagara Mohawk Power Corporation RO (3)

ATTN! Mr. Philip D. Raymond Vice President - Engineering OGC DLZiemann, L:ORB 82 300 Erie Bou1.evard West CJDeBevec, L:ORB //2 Syracuse, New York 13202 RMDiggs, L:ORB II2 SVarga, L:RP Gentlemen:

The Commission adopted amendments to its Regulations in 10 CFR Parts 50, 70, and 73 dated November 6, 1973, which required licensees to submit a physical security plan by January 7, 1974. Each licensee is required to provide physical protection against industrial sabotage and theft of special nuclear materials. Relative to these physical security plans, our position on guards is expressed in section C.l.a of Regulatory Guide 1.17, "Protection of Nuclear Power Plants Against Industrial Sabotage". We have determined'hat an acceptable physica1 security plan must provide for the use of armed guards. We further believe that this feature of the security plan should be implemented as soon as possible, ideally by July 1, 1974.

Please advise us immediately as to your -plans to implement this feature of Regulatory Guide 1.17.

Sincerely, Original Signed by Karl Golly Karl R. Goller, Assistant Director for Operating Reactors Directorate of Licensing cc: Arvin -E. Upton, Esquire Anthony Z. Roisman, Esquire LeBoeuf, Lamb, Leiby 6 HacRae Berlin, Roisman and Kessler 1757 N Street, N. W. 1712 N Street, N. W.

Washington, D. C. 20036 Washington, D. C. 20036 Dr. William Seymour Oswego City Library Staff Coordinator New York State Atomic Energy Council New York State Department of Commerce 112 State Street 0 P P IC 4 3P'7403 L:ORB ItI2; .,.L.:QR.~Zg- '---

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