ML20043H460
| ML20043H460 | |
| Person / Time | |
|---|---|
| Site: | Maine Yankee |
| Issue date: | 06/19/1990 |
| From: | Frizzle C Maine Yankee |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| Shared Package | |
| ML20043H461 | List: |
| References | |
| CDF-90-53, IEB-88-002, IEB-88-2, MN-90-60, NUDOCS 9006250439 | |
| Download: ML20043H460 (4) | |
Text
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MaineVankee-A
@uAstt Ettemcitv Ton MAmThet 1972 I
EDISON DRIVE e AUGUSTA, MAINE 04336 * (207) 622 4868
- j June 19, 1990
-7 MN-90-60 CDF-90-53 1
Proposed Change 153 i
UNITED STATES NUCLEAR REGULATORY COMMISSION 1
Attention:
Document Control Desk
' Washington, DC 20055
References:
(a)
License No. DPR-36 (Docket No. 50-309)
(b) NRC Bulletin No. 88-02 of February 5,1988 - Rapidly Propagating Fatigue Cracks in Steam Generator Tubes.
Subject:
Pro)osed Tech,ical Specification Change No.153 - Steam Generator Tube
'ea(age-j L
Gentlenon:
1 Maine Yankee'hereby submits, pursuant to 10 CFR 50.90, this application,to amend i
sections of the Maine. Yankee Technical Specifications.
This proposed change establishes a specification for maximum reactor coolant primary-to-secondary leakage from any one steam generator of 0.15 gpm and deletes the _ current specification for
_i
--total primary-to-secondary maximum leakage from all steam generators of 1.0 gpm. The proposed modification of this specification is a result of a recent evaluation of steam generator tube inspection indicatior.s.
-l The proposed amendment would mothfy Technical Specification ~ 3.14, " Primary System Leakage" by deleting the current limit of 1.0 gpm from all steam generator tubes and-establishing a limit af - 0.15 gpm from any one steam-generator.
In
. addition, the proposed amendmar.c would add to the basis that primary coolant leakage may be indicated and/or identified by sampling and analysis of steam generator steam
- samples, q
a The reason for this change is that,.as a result of-recent analysis of Maine
. Yankee. steam generator tube inspection indications, a more conservative steam generator tube leakage specification is warranted to ensure early deteci. ion of tube
+
leakage:and to provide sufficient time to initiate corrective actions. Our change L.
in leakage rate-is a result of our analysis of our present leakage specification L'
(<l.0 gpm) as it would be applied to the North Anna tube rupture event promulgated-by Reference (b). In this case, a single leaking tube could reach the point of tube L
rupture prior to exceedance'of the leakage specification value. We have confirmed our analysis techniques are effective in identifying small steam generator leaks at h'
or below the new specification value.
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MaineYankee UNITED STATES NUCLEAR REGULATORY COMMISSION MN-90-60 Attention: Document Control Desk Page 2 A summary of the proposed change, a discussion of its basis and the Significant Hazards Evaluation is presented in Attachraent A.
As discussed in the attachment, t
this change does not involve a significant increase in the probability or consequences of an accident or malfunction of equipment important to safety previously analyzed. Nor does it create the possibility of a new or different kind of accident or malfunction-important to safety.
Lastly, it does not cause i significant reduction in the margin of safety.
Revised Technical Specification pages 3.14-1 and 3.14-2 are included as Attachment B.
This proposed change has been reviewed and approved by the Plant Operation and Review Committee. The Nuclear Safety Audit and Review Committee has also reviewed this submittal.
A representative of the State of Maine is being informed of this request by a copy of this letter.
We request that this proposed change be made effective within 30 days after issuance.
Very truly yours,-
.wp Charles D. Frizzle President WBD:SJJ Attachments c:
Mr. Thomas T. Martin Mr. Eric J. Leeds Mr. Richard J. Freudenberger g'
Mr. Clough Toppan STATE OF MAINE p
Then personally appeared before me, Charles D. Frizzle, who being duly sworn did state that he is President of Maine Yankee Atomic Power Company, that he is duly L
authorized to execute and file the foregoing request in the name and on behalf of l
Maine Yankee Atomic Power Company, and that the statements therein are true to the L
best of his knowledge and belief, skts. $
Abaw Notpfy Public BARGABA1 FAD N NA WYco S
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ATTACHMENT A Summary of Proposed Chanae This. proposed change decreases the maximum steam -generator primary-to-secondary leakage value from 1.0 gpm for all steam generators to 0.15 gpm per individual generator.
When analyzed against the North Anna tube rupture event, the present specification value (1.0 gpm) may not provide sufficient time to permit corrective actions to avoid a tube rupture once the specification is reached. By establishing a lower specification value (0.15 gpm) on a per steam generator basis, a single leaking tube will result in corrective actions being initiated sooner and with high
_ probability of avoiding a follow-on tube rupture event.
The intent of the present steam generator leakage specification value (1.0 gpm) was to provide a reasonable value which conformed to the accepted industry standard with the entire core loaded with pre-pressurized fuel. Decreasing the specification to i
less than 0,15 gpm per steam generator will continue to satisfy the original intent while providing additional assurance that excessive tube leakage would not result in tube rupture prior to corrective actions being carried out.
This specification for primary-to-secondary leakage is not utilized in any of.the FSAR Chapter 14 safety analyses. This specification is strictly operational and was established to alert the operator that corrective action is required to ensure a steam generator tube rupture evert does not occur.
Discussion of Basis for Prooosed Chanae Maine Yankee's original technical specification for steam generator tube leakage was O.2 uCi/ml of I-131 as determined by blowdown sampling. Amendment No. 38 of May 10, 1978 deleted this specification and replaced it with a maximum leakage value from all steam generators of 0.1 gpm.
Amendment No. 53 of March 12, 1981 restored the original I-131 specificatir,n and changed the 0.1 gpm value to 1.0 gpm to be consistent with the industry standards as set forth in the Standard Combustion Engineering Technical Specifications (NUREG-0212, Rev. 2).
Amendment No. 68 of November 29, 1982 for Cycle 7 specified that the total leakage value for all steam generators of.l.0 gpm was further limited to 0.35 gpm for any one steam generator.
Prior'.to Maine Yankee's shutdown on April 7, 1990 for a refueling outage,. increased activity levels had been detected in Steam Generators No.1 and No. 3. ' During the shutdown, leak testing confirmed two tubes in No.1 Steam Generator and one tube in No. 3 were leaking. Non-destructive test results indicated another 23 tubes in No.
l 1 Steam Generator and 13 in No. 3 would also require plugging. Subsequently, No. 2 p
Steam Generator was inspected with 4 tubes indicating a need for plugging.
Maine Yankee's steam generator tube flaws clearly exhibit leak-before-break characteristics. This is based on our leakage experience, the flaw shapes defined -
l; by ultrasonic testing, and preliminary results, from. structural evaluation of the l
l' worst case defect of the specific flaw shapes found. The Maine Yankee flaws probably I
have existed for several cycles and have leaked for a minimum of one cycle.
Maine Yankee is wry interested in identifying the defect mechanism which has resulted in the need to plug 43 tubes during the post Cycle 11 outage. A program to this end has been developed and includes a historical materials and fabrication review by the NSSS vendor, the pulling of one tube and subsequent laboratory analysis, crevice chemistry analysis and assessment, and a Reg. Guide 1.121 analysis.
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-t Until the results. of this effort are known and assessed, a more conservative
. technical specification is appropriate.
l Sionificant Hazards Evaluation
'The proposed change to Technical Specification 3.14 to decrease the allowable steam generator leakage has been evaluated against the standards of 10 CFR 50.92 and has c
been determined to not involve a significant hazards consideration. This proposed change does not:
1.
Involve a significant increase in the probability or consequence of an accident previously analyzed.
Steam generator leakage has not been used i
in any of the FSAR Chapter 14 analyses and thus will not affect the current safety analyses. Assuring that an adequate leakage limit exists that initiates corrective actions in a timely manner is important to ensuring a steam generator tube rupture event does not take place.
2.
Involve a significant increase in the probability or consequence of a malfunction of equipment 1mportant to safety.
The proposed change will 7
E not involve a modification to existing hardware at-the ' plant.
The decrease in the maximum allowable steam generator primary leakage rate tends to provide additional time for operator action to take place which, if timely enough, would avoid the consequences of a tube rupture event.
3..
Create the possibility of. a new or different kind of accident or malfunction of equipment important to safety from any previously-evaluated. Decreasing the leakage rate specification does not create the possibility of a new or different kind of accident since the proposal involves neither a hardware modification nor the creation of a unique operating condition.
4.
. Involve a significant reduction in the margin to safety. Decreasing the-steam generator leakage rate specification does not change the results of i
I any of the FSAR Chapter 14 events.
Rather, it is intended to provide a greater margin of safety since it is more conservative than the present value.
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