ML18093B208

Application for Amend to License DPR-75,providing Alternate Steam Generator Tube Sampling Method When Number of Degraded or Defective Tubes Requires Addl Insp Sample.Fee Paid,

ML18093B208
Person / Time
Site:	Salem
Issue date:	10/10/1988
From:	Miltenberger S Public Service Enterprise Group
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
Shared Package
ML18093B209	List: ML18093B208 ML18093B210
References
NLR-N88164, NUDOCS 8810170166
Download: ML18093B208 (12)

Text

Public Service Electric and Gas Company Steven E. Miltenberger Public Service Electric and Gas Company P.O. Box 236, Hancocks Bridge, NJ 08038 609-339-4199 Vice President and Chief Nuclear Officer October 10, 1988 NLR-N88164 United States Nuclear Regulatory Commission Document Control Desk Washington, DC 20555 Gentlemen:

EMERGENCY LICENSE AMENDMENT REQUEST TECHNICAL SPECIFICATION TABLE 4.4-2 SALEM GENERATING STATION UNIT NO. 2 FACILITY OPERATING LICENSE DPR-75 DOCKET NO. 50-311 Public Service Electric and Gas Company (PSE&G) hereby submits a request to amend Appendix A of Facility Operating License No.

DPR-75 in accordance with 10 CFR 50.90. This request for amendment provides for an alternate steam generator tube sampling method when the number of degraded or defective tubes detected requires an additional inspection sample and the initial

.inspection results indicate the degradation to be confined to a specific area of the tube sheet array or portion of the tube.

It has been determined that the proposed amendment does not involve a significant hazards consideration pursuant to 10 CFR 50.92. A description of the amendment request and the basis for a no significant hazards consideration determination is provided in Enclosure 1. A supporting technical evaluation is provided in Enclosure 2. Enclosure 3 provides the requested revisions of the Salem Unit 2 Technical Specifications.

The proposed change contained in this amendment request represents an acceptable alternative to the course of action prescribed by Table 4.4-2 of the Salem Unit 2 Technical Specifications. The inspection methods used and plant operating precautions to be taken-are identical to those taken for any steam generator tube inspection activity. In addition, the tube failure phenomenon which has prompted this amendment request has similarly occurred at Zion, North Anna, Kewaunee, Trojan, Sequoyah and other plants which provides validity for the proposed alternate sample method.

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Document Control Desk 2 10-10-88 PSE&G has evaluated this request pursuant to 10 CFR 170.21 and has determined that a license amendment application fee is required. A check for $150.00 is enclosed in payment of this fee. In accordance with 10 CFR 50.9l(b) (1), a copy of this amendment request has been sent to the State of New Jersey.

Pursuant to 10 CFR 50.4(b) (2) (ii), this submittal includes one (1) signed original and thirty-seven (37) copies. Should you have any questions regarding this submittal please do not hesitate to contact us.

Sincerely, Enclosures

.Document Control Desk 3 10-10-88 c Mr. J. c. Stone Licensing Project Manager Mr. R. W. Borchardt Senior Resident Inspector Mr. W. T. Russell, Administrator Region I Ms. J. Moon, Interim Chief Bureau of Nuclear Engineering Department of Environmental Protection 380 Scotch Road Trenton, NJ 08628

REF: LCR 88-12 STATE OF NEW JERSEY )

) SS.

COUNTY OF SALEM )

Steven E. Miltenberger, being duly sworn according to law deposes and says:

I am Vice President and Chief Nuclear Officer of Public Service Electric and Gas Company, and as such, I find the matters set forth in our letter dated October 10, 1988 , concerning Salem Generating Station, Unit No. 2, are true to the best of my knowledge, information and belief.

Subscribed and Sworn to before me

,this _&f~ day of o~

L

,. -,_* :a/).. "/)/)a

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, 1988

• . *'/

- , ** ~9tary J'ublic of New Jersey

,, -~ ...... ' j EILEEN M. OCHS NOTARY PUBLIC OF NEW JERSEY My Commlulen Exptrts Julf 16, 1892 My Commission expires on

ENCLOSURE 1 REQUEST FOR AMENDMENT SALEM GENERATING STATION UNIT NO. 2 FACILITY OPERATING LICENSE DPR-75 DOCKET NO. 50-311 Description of Change The following statements shall be included in Salem Unit 2 Technical Specification 4.4:

"During the Salem Unit 2 Fourth Refueling Outage, indications associated with wall degradation were detected on the tubing of the No. 22 and No. 24 Steam Generators. The condition was established as occurring on the inside diameter of the Row 1 tubes in the tangential region of the u-bend.

The following alternate action may be taken in place of that required by Technical Specification Table 4.4-2 when the results of the initial sample requires that an additional sample or samples must be inspected and the condition for which the added inspection is required is limited to the Row 1 and/or Row 2 tubes. When examination results fall into a C-2 or C-3 Supplemental Sample Category, pursuant to Technical Specification Table 4.4-2 as a result of Row 1 and/or Row 2 u-bend defective or degraded tubes, additional samples may be limited to Rows 1 and

2. The results of the examination of the Row 1 and Row 2 tubes will be exempt from the additional sampling requirements of Technical Specification Table 4.4-2."

This change applies to only those steam generator eddy current inspections performed during the Salem Unit-2 Fourth Refueling Outage.

Reason for Change Eddy current examinations have been performed on the No. 22 and No. 24 Steam Generators during the Salem Unit 2 Fourth Refueling Outage. The number of tubes to be inspected in the first sample were calculated in accordance with the formula in Technical Specification Table 4.4-2 and consisted of 204 tubes in No. 22 Steam Generator and 204 tubes in No. 24 Steam Generator. An additional 609 tubes were examined in No. 22 Steam Generator for conditions related to the 1987 North Anna Unit 1 steam generator tube rupture incident, as well as other areas of the steam generator where previous history indicated that examinations should be performed.

During the last operating cycle, primary to secondary system leakage was detected in both the No. 22 and No. 24 Steam Generators. This leakage was monitored until plant shutdown for the Fourth Refueling outage. Just prior to shutdown, the primary to secondary leakage measured 4 to 17 gpd for No. 22 steam Generator and 1 to 4 gpd for No. 24 Steam Generator.

.To pinpoint the leaking tube(s), a helium leak test was performed on the No. 24 Steam Generator (this test has not been performed on the No. 22 Steam Generator as yet). The helium leak test detected three (3) leaking tubes in Row 1 of No. 24 Steam Generator. These leaking tubes have been subsequently confirmed by eddy current examination. The results of the eddy current examination of the first sample (204 tubes) on No. 24 Steam Generator revealed 45 defective tubes, all in Row 1.

The results of the eddy current examination of No. 22 Steam Generator revealed 46 defective tubes, all in Row 1. In addition, the eddy current inspection for North Anna considerations revealed no defective or further degraded tubes.

[No. 24 steam generator had already been evaluated for the North Anna considerations using previous eddy current data. This evaluation resulted in two tubes which are to be plugged during the Fourth Refueling Outage in order to preclude conditions similar to those required to produce a tube failure such as that which occurred at North Anna Unit 1. However, the tube plugging will be performed due to the North Anna considerations and not due to an excessive level of tube wall degradation.]

The results of the eddy current examinations of the Row 1 tubes of No. 22 and No. 24 steam Generators place both generators in a C-3 examination sample category pursuant to Technical Specification Table 4.4-2. Adoption of the C-3 sampling scheme in this instance would require a total inspection of the No. 22 and No. 24 steam Generators and a 4S sample (813 tubes) for each of the No. 21 and No. 23 Steam Generators (if no other defects are discovered on No. 21 and No. 23).

PSE&G believes that adoption of this supplemental sampling scheme is unnecessary and not technically justifiable considering the nature of current examination results. The identified degradation is confined to a limited region (Row 1). These results are indicative of a known problem with Westinghouse Series 51 Steam Generators, i.e., defects in the tangential region of the u-bend of Row 1 tubes. Westinghouse has advised PSE&G that the defects identified in these first sample eddy current examination results of the No. 22 and No. 24 Steam Generators are similar to those discovered in Row 1 examinations at Zion, North Anna, Kewaunee, Trojan, Sequoyah, and other plants.

Since the discovered defects are confined to a limited region and are indicative of an established phenomenon related to Row 1 tubes of Westinghouse Series 51 steam generators, inspection of additional tubes outside the area of interest would not appear to be pertinent. If performed as currently required by the Technical Specifications, additional examination would be required in areas of the steam generators that have historically been essentially clean of defective and degraded tubes (see Enclosure 2). PSE&G has estimated that approximately 3 weeks of additional critical path time would be required to perform the examination prescribed by Technical Specification Table 4.4-2.

This additional outage time does not appear to be justified in terms of significant information provided and any increase in safety realized.

Significant Hazards Consideration Analysis The standards used to arrive at a determination that a request for amendment involves no significant hazards consideration are included in the Commission's regulations, 10CFR50.92. These regulations state that no significant hazards considerations are involved if the operation of the facility in accordance with the proposed amendment would not: (1) involve a significant increase in the probability 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. Each standard is discussed as follows:

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 'I a new or different kind of accident from any previously I 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.

.PSE&G concludes that this amendment is not likely to involve a significant hazards consideration since it does not involve a process or plant operating condition which is different from or less conservative than any previously evaluated. The change involves a variation of the sampling scheme for an established inspection process.

Bases for Emergency Circumstance The Salem Unit 2 (and Salem Unit 1) steam generators have had an excellent performance record and have historically exhibited minimal tube degradation. PSE&G attributes this performance record to a very effective AVT chemistry program as well as other steam generator operation and maintenance and program enhancements. For this reason, PSE&G could not foresee the extent of tube degradation found during the Salem Unit 2 Fourth Refueling Outage in the Row 1 tubes of the No. 22 and No. 24 Steam Generators. The tube degradations on Row 1 appear to have followed the classic pattern for their onset, i.e., a prolonged period of operation with no apparent degradation followed by an abrupt occurrence of multiple tube defects.

Since the tube degradation appears to be the result of a known Westinghouse Series 51 steam generator problem, PSE&G believes that subsequent inspection in accordance with Technical Specification Table 4.4-2 and the associated additional outage time required to do the inspection are both unnecessary and not justifiable from a technical standpoint. A technical evaluation which discusses the Row 1 phenomenon as well as the reasons behind the proposed alternate sampling scheme is included in Enclosure 2.

Environmental Impact Appraisal Employment of the proposed alternate inspection method will involve no change in effluent types or total amounts. The change does not involve an increase in power level. Therefore, PSE&G concludes that the proposed change involves no significant environmental impact and should be excluded, pursuant to 10 CFR 51.22, from the need for NRC preparation of an environmental impact statement and environmental impact appraisal.

Compensatory Measures PSE&G recognizes that the proposed alternative sampling method is not as comprehensive as that provided in Technical Specification Table 4.4-2. However, as noted above, PSE&G believes that the reason for the observed tube degradations is readily discernible and that subsequent inspection in accordance with Table 4.4-2 is not warranted.

_To preclude the occurrence of Row 1 tube failures during the upcoming Salem Unit 2 operating cycle, the Row 1 tubes of all four Salem Unit 2 steam generators will be plugged in addition to any other tubes which are required to be plugged as a result of the eddy current examination of the Row 2 tubes of all four steam generators. PSE&G also plans to inspect the Row 1 and Row 2 tubes of all four Salem Unit 1 steam generators during the upcoming Salem Unit 1 refueling outage scheduled to commence in March 1989. A similar change request will be submitted in the near future to address the need for a similar alternative sampling method should future Salem Unit 1 steam generator eddy current examinations result in the discovery of similar problems with the Row 1 tubes. With the plugging of the Row 1 tubes in all the Salem Unit 2 steam generators, a safety evaluation is to be performed to assure that safety and flow margins are not adversely affected.

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ENCLOSURE 2 TECHNICAL EVALUATION The information presented below is intended to highlight the acceptability of the proposed alternate inspection scheme by briefly presenting the history of the Salem Unit 2 steam generators and the results of inspections performed during the current refueling outage.

Salem Unit 2 incorporates four (4) Westinghouse Series 51 steam generators. Each generator contains 3388 u-bend tubes fabricated of Inconel 600.

These generators have been in operation since August 1980 and have been subject to the following Inservice Inspections since that time.

Date Steam Generator February 83 21, 22, 23, 24 December 84 21, 22, 23, 24 November 86 21

• November 87 24

• • October 88 22, 24

• Outage to repair steam generator tube leak.

• • Current outage with inspections of No. 21 and No. 23 Steam Generators still to be performed.

The history of the tube degradation in these generators consists of relatively few defective or degraded tubes with no apparent inservice corrosion related denting. A summary* of indications categorized by the attributable generic cause is shown in the attached table.

Eddy current examinations performed during the current refueling outage consisted of examining 204 tubes in No. 24 Steam Generator concentrating on Row 1 and Row 2 tubes, and 813 tubes in No. 22 Steam Generator which included Row 1 and Row 2 tubes as well as other areas of interest. The results of these initial examinations have shown a significant increase in the number of defective tubes in Row 1 of both steam generators. The results identified 45 tubes in Row 1 of No. 24 Steam Generator and 46 tubes in Row 1 of No. 22 Steam Generator with indications evaluated as tangent cracking in the u-bend area. No other indications were identified in any other area of either steam generator.

Primary side stress corrosion (PWSCC) cracking in Row 1 u-bends has been most prevalent in Westinghouse Series 51 steam generators. As indicated above, Salem Unit 2 experienced two (2) leaking tubes in November 1987 with this phenomenon.

Prior to this date, Salem Unit 2 had shown no indications of this phenomenon. Westinghouse has informed PSE&G that "low" row u-bend PWSCC is considered a high risk mechanism in the context of growth rate. This is substantiated by the fact that once the phenomenon was detected in November 1987 (with the two leaking tubes in No. 24 steam generator), the number of defective tubes expanded to 45 by October 1988.

Based on the above information showing this phenomenon concentrated in the low rows (Rows 1 and 2), and with all indications in No. 22 and No. 24 Steam Generators in Row 1, PSE&G has elected to plug all Row 1 tubes in all 4 steam generators as a precautionary measure. In addition, examinations have been expanded to include 100% of Row 2 tubes in No. 22 and No. 24 steam Generators. The results of these additional examinations have shown no indications in Row 2 tubes. Also, examinations will be expanded to include examinations of 100% of Row 1 and Row 2 tubes in No. 21 and No. 23 steam generators.

CONCLUSION The history of the Salem Unit 2 steam generators prior to November 1987 had been essentially trouble free. Beginning in November 1987, and accelerating in October 1988, low row u-bend PWSCC has been detected. As indicated by Westinghouse, this phenomenon is prevalent in Series 51 steam generators and is concentrated in Row 1, occasionally showing up in Row 2. With the plugging of the Row 1 tubes in all 4 steam generators and the examination of 100% of Row 2 tubes in all 4 steam generators, the known affected areas of these generators will have been addressed. -

Examination of other areas of the steam generators would not produce significant additional information or an increase in safety.

. I SALEM UNIT 2

SUMMARY

OF EDDY aJRRENT INDICATIONS CATEx;ORIZED BY GENERIC CAUSE No. 21 steam No. 22 steam No. 23 steam No. 24 steam catego:ry Generator Generator Generator Generator

'l\Jbe SUpport Plate No Indications One (1) 'l\Jbe Plugged One (1) 'l\Jbe Plugged Seven (7) Tubes with Indications Five (5) Tubes with Ten (10) Tubes with Indications Indications Indications Anti Vibration Bar TWo ( 2) 'l\Jbes No Indications Five (5) Tubes with Seven (7) Tubes with Abrasion with Indications Indications Indications, 4 tubes plugged

'l\Jbe Iane Blocking 10 'l\Jbes Plugged 10 Tubes Plugged 10 Tubes Plugged 10 Tubes Plugged Device IEnage Foreign Object. No Indications No Indications No Indications One (1) 'l\Jbe Plugged IEnage Row 1 Tangent *No Indications 46 Tubes with *No Indications 45 Tubes with Indications Cracking Indications One (1) 'l\Jbe Plugged North Anna No Action Required No Action Required No Action Required TWo (2) tubes to be plugged Considerations during Fourth Refueling outage

• Prior to inspection to be perfonned during Salem Unit 2 Fourth Refueling outage L