CY-86-031, Rev 1 to 4.10.1(D) Inservice Insp of Steam Generator Tubes (Acceptance Criteria)

Rev 1 to 4.10.1(D) Inservice Insp of Steam Generator Tubes (Acceptance Criteria)

ML20205T137
Person / Time
Site:	Haddam Neck File:Connecticut Yankee Atomic Power Co icon.png
Issue date:	05/08/1986
From:	Blaisdell J, Kai M CONNECTICUT YANKEE ATOMIC POWER CO.
To:
Shared Package
ML20205T117	List: CY-85-062, Rev 2 to Steam Generator Tube Sleeving & Plugging CY-86-031, Rev 1 to 4.10.1(D) Inservice Insp of Steam Generator Tubes (Acceptance Criteria) ML20205T113 ML20205T120 ML20205T123 ML20205T153
References
ISE-CY-86-031, ISE-CY-86-031-R01, ISE-CY-86-31, ISE-CY-86-31-R1, NUDOCS 8606130061
Download: ML20205T137 (4)

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INTEGRATED SAFETY EVALUATION N0/ ISE/CY-86-031 (bi/o ') y PLANT: CONNECTICLIT YANKEE '

MSCR NO.: l TITLE: 4.10.1 (D) INSERYlCE INSPECTION OF STEAM SENERATOR TU8ES l i

(ACCEPTANCE CRITERIA) aEFERENCES

1. M. R. Galler, M. F. Ahern, Component Engineering Safety Evolustion, Deted 5/8/86.

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2. L. J. Laskowski, J. W. Kilstowicz, Nuclear Noterials and Chemistry Safety Evoluetion, Dated 5/6/06.

, DESCRIPTl@d 7 CHANGE The maximum imperfection depth of a steem generator tube permitted by the present Technical Specifications is 505 of the nominel well thickness.

Tubes with defects larger then this are supposed to be removed from service by plugging. As a result of a transposing error, e tube that should have been plugged during the recent refueling outage wee inadvertently left in service. Eddy current testing indicates that this tubs [ tubs no. R37C73 in steem generator no. 2] has a pit type defect which is 552 of the nominal well thickness.

This Technical Specification change proposes to permit operation for one cycle without removing the tube from service.

EFFECT ON DESIGN 8 ASIS ANALYSES The occident onelysis potentially offacted by this proposed change is the steem generator tube rupture. As indicated in Reference 2 the progression rate of pit defecte is bounded by 182 and, es indicated in Reference 1, I structural intopity is ensured if the most limiting type defects de not exceed 892 through well during the cycle.

Since the 552 defect (plus a 105 ellowance for measurement uncertefatg)le not expected to exceed 835 by the next refueling and since pit tlpe defects are not expected to result in structural failure until well beyond 892 '

through well, the probabillig of a tube rupture event le not increened by the proposed change. - -

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Since the proposed change is not expected to. increase. the nupnber.sf tubee . zu , .

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that era assumed to rupture in the occident snelyste, the proposed change .

hee no effect en the consequences of the steam 0enerater tube rtpture e -

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Since the proposed change will neither offact equipment operability nor equipment performance, it will not have eng offact on the operation of eng equipment important to safety.

Because of the above essessments, the proposed change to Technical Specifications will not increase the probability of occurrence or the l consequences of a previousig enelyzed accident nor effect the operation of '

eng equipment importent to safety.  ;

POTENTIAL FOR CREATING AN UNANALYZED ACCIDENT ,

As indicated above, permitting one cycle of operation with a steem l generator tube having a pit type defect of 552 does not degrade the i structural integrity of the steem generator tube. Since the proposed change to the Technical Spectficettons does not:

e. effect plant operating conditions,

b. effect the weg in which eng equipment is operated, and

c. create eng new failure modes no occidents are created which ero of a different tipo then previousig i enelgred.

l EFFECT (Mi THE MARGIN OF SAFETY l The steem generator tube forms e part of the RCS pressure boundery. The tubes era manufactured with a well thickness much greater then the l minimum well thickness necessary to withstand the stresses due to normel operetton and design bests occidents. Although not clearly specified in the l ' basis of the present Technical Specificetton, the 502 limit is chosen to

, ensure that, assuming a conservative progreeston rate, defects do not degrade this minimum thickness before the next tube inspection. Using the guidance of Reg Guide 1.121, the elloweble throup well defect should be chosen so that the defect would not exceed 892 through well before the next inspection. The remaininal 12 is the marnin of safetu which.esoures that a tube with a pit tipo defect will not fell structure 11g. As stated in R,efemnce 1, single large pits up to 922 through well have a grooter mergin to burst then 502 through well uniform 1g thinned tubes. Therefore, this criterion for structurel integrity is conservettve for pit type defects. In addition es stated in Reference 2, the progression rete of defects in the Connecticut Yankee steem generator tubes has been shown to be bounded by

~182. As a result, the 552 defect (plus e 102 ellowance for moseurement

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. Page 3 uncertelnty) is not expected to increase beyond 832 before the next refueling outage. Because of the progression rate, the mergin of safety which is the bests of this Techn!cel Specification will not be reduced during j one cycle's operation. -

SuttMRY The changes proposed by ties PTSCR era considered to be safe and do not constitute on unroviewed safety question or a significant hazard consideration per the requirements of 10CFR50.59 and 10CFR50.92 since it does not:

1. Increase the probability of occurrence or the consequences of en accidont or malfunction of equipment important to safety previously evolueted in the safety eneigsts report,

2. create the possibility for en accident or malfunction of a different type then previously analyzed in the safety enelgeis report,

3. reduce the mergin of safety as defined in the bests of eng technical specification.

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M. S. Kef, Supervisor

$ 4AAf 79M'

h. A. Slotedell, Meneger Transient Analysis Safety Anelgets i

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C Appendix B 1). . Integrated Safety Evaluation for Steam Generator Tube Sleeving and Plugging, (10-pages) 2). Safety Evaluation - Connecticut Yankee Steam Generator Tube Repair (11-pages)

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