ML18093B287
| ML18093B287 | |
| Person / Time | |
|---|---|
| Site: | Salem  |
| Issue date: | 11/01/1988 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML18093B288 | List: |
| References | |
| NUDOCS 8811080228 | |
| Download: ML18093B287 (5) | |
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UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C. 20555 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION SUPPORTING AMENDMENT NO. 63TO FACILITY OPERATING LICENSE NO. DRP-75 PUBLIC SERVICE ELECTRIC & GAS COMPANY PHILADELPHIA ELECTRIC COMPANY DELMARVA POWER AND LIGHT COMPANY ATLANTIC CITY ELECTRIC COMPANY SALE~ GENERATING STATION, UNIT NO. 2 DOCKET NO. 50-311
1.0 INTRODUCTION
By letter dated October 10, 1988, Public Service Electric & Gas Company (the licensee) requested a change to the Salem, Unit ~Technical Specifications concerning steam generator (SG) tube surveillance reouirements.
The requested change involves relief from the supplemental tube sample inspection requirements in Table 4.4-2 of the Salem, Unit 2 Technical Specifications and would be applicable to thP. fourth refueling outage only.
This amendment was authorized by telephone on October 14, 1988, and confinned by letter on October 14, 1988.
The initial SG inspection program for the fourth refueling outage called for inspection of two of the four SGs; namely, SGs 22 and 24.
Based on the licensee's October 10, 1988 submittal and on infonnation provided to the staff by phone on October 11, 1988 and October 13, 1988, the scooe of the inspection program was as follows:
SG 22:
0 All row 1 tubes that were unplugged 0
50% of all row 2 tubes 0
All peripheral tubes 0
All tubes with previous indications (approximately five tubes based on the October 10, 1988 submittal) 0 609 tubes in rows 8 to 12, as necessary to satisfy bulletin 88-02 0
A few additional tubes randomly selected.
Total:
813 tubes
SG 24: 0 All row 1 tubes that were unplugged 0
50% of all row 2 tubes 0
All peripheral tubes 0
A)l tubes with previous indications (approximately 14 tubes based on the October 10, 1988 submittal) 0 A few ~dditional tubes, randomly selected Total_:_,
..:~ 204 tubes Forty-six row 1 tubes in SG 22 and 45 row 1 tubes in SG 24 were found to be defective, all with indications at the U-bend tangent point locations.
No other new indications were found in any other location of either SG.
The few tubes with previous indications did not show significant increase in depth of the indications and none of these indications were found to require plugging the tube.
Based on these findings the licensee has elected to plug.all row 1 tubes in each of the four SGs, regardless of whether or not.they ex hi bit indications *. In addition, the licensee has expanded the initial inspection program to include all row 2 tubes in each of the four SGs.
This expanded inspection scope, however. does not fully satisfy the supplemental sampling requirements in Table 4.4=2 of the Technical Specifications. Based on the number of defective tubes 'found (all in row 1), the Technical Specifications require that the inspection scope be expanded to include all tubes in SG 22 and 24 and an additional 6% (about 200 tubes) in each of SGs 21 and 23.
The licensee believes that the supplemental sample inspections called for by the Technical Specifications to be unnecessary and not technically justified considering that all of the defective indications found involve a degradation mechanism known to be confined to the inner rows (rows 1 and 2 tubes of Westinghouse series 51 SGs).
Accordingly, the licensee has proposed a change to the Technical Specifications, applicable only to the fourth refueling outage at Salem, Unit 2, which would limit the required supplemental sample inspections to all row 1 and row 2 tubes.
2.0 EVALUATION The row 1 U-bend tangent point indications at Salem, Unit 2 are typical of those which have been found at numerous other Westinghouse plants.
These indications are attributable to primary water initiated, stress corrosion cracks (PWSCC).
High residual stresses associated with the fabrication of the small radius U-bends have rendered the tangent point locations of these U-bends susceptible to PWSCC.
Extensive industry experience has shown these cracks to be entirely limited to row 1 and row 2 tubes.
The vast majority of these cracks have occurred in row 1 tubes because these tubes have the smallest U-bend radius and, thus, the highest residual stresses.
Based on the above and (1) that all row 1 tubes are being plugged, (2) that all row 2 tubes are being inspected, and (3) the absence of significant further degradation of the few previously observed indications for tubes located beyond row 2 (at the support plates and
.. anti-vibration bar supports) we find the licensee's proposed change to be acceptable.
3.0 EMERGENCY CIRCUMSTANCES Prior history of th~ operation of the Salem, Unit 2 steam generators has shown an excellent record of performance with minimal tube degradation.
The licensee attributes this performance record to a very effective all volatile treatment {AVT) of secondary water as well as other program enhancements. These failures have followed the classic pattern of onset, i.e., a prolonged period of operation with no apparent degradation followed by an abrupt occurrence of multiple tube defects. Also, Salem, Unit 1 has not experienced the same type of failure P.ven though it has been in operation about five years longer than Salem, Unit 2.
At the time of discovery of the defects there was insufficient time to submit an amendment request utilizing the normal procedure, obtain approval and perform the necessary inspection without impacting the restart date.
Without the requested change, the required inspections. would have extended the current outage by about three weeks. Accordingly, the staff concludes that the licensee has satisfied the requirement of 10 CFR 50.91(a)(5), and that a valid emergency exists.
4.0 FINAL NO SIGNIFICANT HAZARDS CONSIDERATION
DETERMINATION The Commission's regulations in 10 CFR 50.92 state that the Commission may make a final determination that a license amendment involves no significant hazards consideration if operation of the facility in accordance with the amendment would not:
(1) involve a significant increase in the probahility or consequences of an accident previously evaluated; or (2) create the possibility of a new or different kind of accident from any accident previously evaluated; or (3) involve a significant reduction in a margin of safety.
The licensee has determined and the staff agrees that:
- 1.
Operation of the facility in accordance with the proposed amendment would not involve a significant increase in the probability or consequences of an accident previously evaluated.
The proposed inspections are an acceptable alternative to the course of action prescribed by Table 4.4-2 of the Technical Specifications in that they are concentrated upon a more strategic area of the steam generator based on the initial eddy current examination results. The inspection method used for the proposed sampling scheme is identical to that currently employed.
Accordingly, there would be no change in the probability or consequences of an accident previously evaluated.
- 2.. Operation of the facility in accordance with the proposed amendment would not create the possibility of a new or different kind of accident from any previously evaluated.
- The inspection methods used for the proposed sampling scheme are identical to those used at present. Plant operating precautions are the same as those taken for any steam generator tube eddy current inspection activity.
No new or different kind.of accident from any accident previously evaluated can be postulated.
- 3.
Operation of the facility in accordance with the proposed amendment would not involve a significant reduction in a margin of safety.
Again, inspection methods used and plant operating precautions taken are identical to those taken for any steam generator tube eddy current inspection activity. Thus, no margin of safety is affected by the proposed change.
Based on the above considerations the staff concludes that the amendment involves no significant hazards consideration.
5.0 STATE CONSIDERATION The State of New Jersey was contacted on October 14, 1988, on this matter and they had the following questions:
(1)
Q.
Would the steam generators be 100% inspected at the next outage?
A.
Relief granted with this change would not require the SGs to be 100% inspected at the next outage.
Only a normal sample, in accordance with Table 4.4-2 would be required.
(2)
Q.
Will the required inspection frequency now be 20 months as stated in Technical Specification 4.4.6.3.b because the inspection results fell in the Category C-3?
A.
Yes, Technical Specification 4.4.6.3.b is applicable and the next two SG tube inspections will be at 20 month maximum interval.
The State of New Jersey had no further comments.
6.0 ENVIRONMENTAL CONSIDERATION
This amendment involves a change with respect to a surveillance requirement.
The staff has determined that the amendment involves no significant increase in the amounts, and no significant change in the types, of any effluents that may be released offsite and that there is no significant increase in individual or cumulative occupational radiation exposure.
The Connnission has made a final no significant hazards consideration finding with respect to this amendment.
Accordingly, this amendment meets the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9). Pursuant to 10 CFR 51.22{b), no environmental impact statement or environmental assessment need be prepared in connection with the issuance of this amendment.
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- 7. 0 CONCLUSION The staff has concluded, based on the considerations discussed above, that:
(1) the.amendment does not (a) significantly increase the probability or consequences of an accident previously evaluated, (b) increase the possibiJity of a new or different kind of accident from any previously evaluated or (c) significantly reduce a safety margin and, therefore, the a~e~dment does not involve significant hazards consideration; (2) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, and (3) such activities will be conducted in compliance with the Commission's regulations and the issuance of this amendment will not be inimical to the co11111on defense and security nor to the health and safety of the public.
Principal Contributors:
E. Murphy and J. Stone Dated:
November 1, 1988
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