ML19275A513
| ML19275A513 | |
| Person / Time | |
|---|---|
| Site: | Yankee Rowe |
| Issue date: | 09/25/1979 |
| From: | Jabbour K Office of Nuclear Reactor Regulation |
| To: | Crutchfield D Office of Nuclear Reactor Regulation |
| References | |
| TASK-03-05.A, TASK-3-5.A, TASK-RR NUDOCS 7910040580 | |
| Download: ML19275A513 (7) | |
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stess sS Docket No. 50-29 MEMORANDUM FOR: Dennis Crutchfield, Chief Systematic Evaluation Program Branch, D0R FROM:
Kahtan Jabbuur Systematic Evaluation Progrr Branch, D0R
SUBJECT:
SUMMARY
OF MEETING WITH YANKEE ATOMIC TLECTRIC COMPANY ON HIGH ENERGY LINE BREAK INSluE CONTAINMENT FOR YANKEE R0WE (SEP TOPIC III-5.A Representatives of the Nuclear Regulatory Commission (NRC) and Yankee Atomic Electric Company (YAEC) met at Yankee Rowe to discuss the System-atic Evaluation Program (SEP) Topic III-5.A, " Effects of Pipe Break on Structures, Systems and Components Inside Containment", on Septecer 17, 1979. A list of attendees is provicea 1n %ttachment 1.
The meeting started with brief introductory discussions on the purpose of the visit and the criteria for postulating break locations anc break scenari os. Following individual whole Dooy radiation counts, the group dressed in protective clothing and entered the Yankee Rowe containmer.t s tructure. The purpose of containment entry was to view from different locations within containment the high and moderate energy piping layout and supports relative to pipe break inside containment. With this objective, piping, compartmentation, electrical cable trays, conduit runs, penetration areas, safety systems including instrumentation and other components that could be affected by piae whip or jet impingement in the unlikely event of a pipe break were assessed.
Individual whole body raaiation counts were repeated on exit from coritainment.
YAEC has utilized the effect oriented approach (for evaluating the high energy line break effects) described in the attachment to the NRC letter to KMC dated July 20, 1978. This approach postulates a high energy pipe break inside containment near safety equipment and analyzes the capability of the remaining systems to safely shutdown the reactor.
Licensee representatives discussed the interaction of the breaks (pipe whip and jet impingement) with the safety systems required to shutdown the plant.
The NRC representatives requested the licensee to study the pipe whip and jet impingement effects of the breaks postulated under NRC TASK ACTION PLAN (TAP) A-2 and to consider these effects for postulated 1101 022 0040 291 p
. breaks in the primary coolant loop at locations other than those required in TAP A-2 using either the mechanistic or effect oriented approach. The NRC representatives agreed to further review the interface between A-2 and SEP Topic III-5.A to assure that there is no unnecessary duplication of effort.
The licensee stated that the consideration of a whipping pipe as having sufficient energy to potentially rupture an impacted pipe of equal or greater nominal pipe size and equa. or greater wall thickness, and the consideration of the effects of jet impingement loads from a ruptured pipe on a pipe of equal or greater nominal size are two escalations of current criteria. The NRC representatives agreed to attempt to resolve this concern in the near future.
The NRC representatives made the following statements concerning the effect oriented approach:
1.
The safety objectives are:
A.
To maintain a coolable core geometry following any postulated break.
B.
To maintain the capability of safe plant shutdown (definition of safe shutdown consistent with tnat of safe shutdown reviews).
C, To maintain containment integrity.
The limits of 10 CFR Part 100 will be applied in determining the acceptability of the review.
2.
It is of utmost importance that the consequences of each pipe break scenario be fully recognized and understood bafore a decision would be nace on any proposed resolution. The staf; further stated that pipe breaks should be considered at locations close to safety-related equipment (as stated in the enclosure to the NRC letter to KMC dated July 20,1978). Consideration must be given to the effects of larger pipe damaging smaller pipes and causing multiple failures of piping, jet impingement and single failure. The methods of calculating the effects of jet impingement are discussed in the NRC Standard Review Plan (SRP), Section 3.6.2 or in the proposed ANS-58.2 ( ANSI-N176) dated January 1979. Other types of enveloping solutions may be generated by the licensee and will be reviewed by the NRC staf f.
The single failure criteria to be used by the NRC staff in their review will be that of ANS-51.7, Draf t 4; Rev.1, November 1975, which states that the most li'niting single failure will be taken in addition to the initiating break and its effects.
The most limiting single failure can De taken either as a single active failure in the short-term E a single activa g passive failure in the long-term. Short-term, long-term and the nature of the passive fcilure are defined in the standard.
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. 3.
General Design Criterion No.17 and SRP Section 3.6.1 (BTP APCSB 3-1) will be employed relating to loss of offsite power; however, on a plant-by-plant basis, operational experience will be considered.
4.
Credit for operator action will be considered on a case-by-case basis once the scenarios have been developed.
5.
No breaks need be postulated in the piping of those fluid systems that qualiflt as high energy fluid systems for only short operational periods. An operational period is considered "short" if the fraction of time that the system operates above the pressure or temperature threshold values specified for high-energy fluid systems is less than eit*.er:
(a) Two percent of the tirrc that the system operates as a moderate-energy fluid; or (b) One percent of the time that the plant operates.
The NRC representatives also made the followirg statements on the mechanistic approach:
1.
A minimum of two intermediate breaks should be postulated for each piping run in addition to terminal ends as stated in Regulatory Guide 1.46 and NRC Standard Review Plan 3.6.2.
Intermediate breaks should be separated from each other and the terminal ends by a change in direction.
If the piping un has only one change or no change in direction, only one inten..ediate break need be post-ulated.
2.
In applying criteria for postulating pipe break effects on structures, systems and components inside containment, it is acceptable to app?j the criteria presently utilized for Class 2 and 3 high energy piping systems (i.e. BTP MEB 3-1) to piping systems designed and analyzed in acordance with B31.1 since the design and stress criteria for such systems are equivalent provided omission is not made with respect to loads required to be evaluated.
The licensee requested that augmented in-service inspection (ISI) be consi-dered as a means to mitigate the consequences of the postulated pipe breaks where retrofitting or adding restraints ic impractical.
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, At the conclusion of the meeting, the licensee stated that their prelim-inary effort (i.e. break locations determined and effects of Dreaks at those locations) will be completed prior to the end of November. However, the final resolution of the unacceptable pipe break effects and/or the methods of mitigating the unacceptable ef fects will not De available by the end of November. The licensee suggested a meeting at that time.
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Kahtan Jabbour Systematic Evaluation Program Branch Division of Operating Reactors Atachment:
As stateo I101 025
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DISTRIBUTION FOR MEETING SUMMARIES Docket f NRC PDR Local PDR Central Files TERA SEPB Reading NRR Reading H. Denton E. Case L. Shao D. Eisenhut R. Vollmer W. Kussell B. Grimes T. Carter T. Ippolito R. Reid G. Knighton V. Noonan A. Schwer,r D. Ziemann D. Crutchfield G. Lainas J. Scinto, OELD Ol&E (3)
ACRS (16)
Licensees NRC Participants D. Knuth'fstall, KMC KPC R. Schaf J. Stacey, YAEC P. Rainey, YAEC L. Dergay, YAEC D. Hansen, YAEC N. St. Laurent, YAEC L. French, YAEC 1101 026
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ATTACHMENT 1 LIST OF ATTENDEES SEPTEMBER 17, 1979 Yankee Atomic Electric Company J. Stacey P. Rainey L. Dergay D. Hansen N St. Laurent L. French KMC R. Schaffstall NRC K. Jabbour P. DiBenedetto 1101 027