ML20045G683

Application for Amends to Licenses NPF-4 & NPF-7 Modifying Table 4.4-1 of TS 4.4.5.1 to Reduce Minimum Number of SGs Required to Be Opened for Insp During First Insp (I.E.,Refueling Outage)Following SG Replacement

ML20045G683
Person / Time
Site:	North Anna
Issue date:	07/02/1993
From:	Stewart W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20045G684	List: ML20045G683 ML20045G688
References
NUDOCS 9307150044
Download: ML20045G683 (8)

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. VIROINIA ELECTHIC AND POWElf COMPANY Ricnuoxu,VIMUINIA 20261 July 2, 1993 t

U.S. Nuclear Regulatory Commission - Serial No. 93 376 Attention: Document Control Desk NL&P/JBL: R2-  :

Washington, D.C. 20555 Docket Nos. 50-338- ,

339 Ucense Nos. NPF-4 'i NPF-7  ;

Gentlemen: i VIRGINIA ELECTRIC AND POWER COMPANY >

NORTH ANNA POWER STATION UNITS 1 AND 2 i i

PROPOSED TECHNIC AL- SPECIFICATIONS CHANGE STEAM GENERATOR INSPECTION SCOPE- REDUCTION Pursuant to 10 CFR 50.90, the Virginia Electric and Power Company requests amendments, in the form of a change to the Technical Specifications, to Facility Operating License Nos. NPF-4 and NPF-7 for North Anna Powcr Station Units 1 and 2,  ;

respectively. The proposed change would modify Tc.ble 4.4-1 of Technical _ <

Specification 4.4.5.1 to reduce from two to one the minimum number of steem  !

generators required to be inspected during the first inservice inspection following- 1 steam generator replacement. This change would considerably reduce resources.  ;

required for these first outages without any corresponding reduction in nuclear safety.

A discussion of the proposed Technical Specifications change is provided in .

Attachment 1. The proposed Technical Specifications change is provided in 4 Attachment 2. It has been determined that the proposed Technical Specifications '

change does not involve an unreviewed safety question as defined in 10 CFR 50.59 or '

a significant hazards consideration as defined in 10 CFR 50.92. The basis for our determination that the change does not involve a significant hazards consideration is provided in Attachment 3. The proposed Technical Specifications change has been reviewed and approved by the Station Nuclear Safety and Operating Committee and the Management Safety Review Committee.

Should you have any questions or require additional information, please contact us.

Very truly yours g 7 [/,)qfTan ? N i W. L. Stewart i Senior Vice President - Nuclear l

Attachments i

1Onnon ,, ,

9307150044 930702 p' G PDR ADOCK 05000338 e p PDR y \

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k cc: U.S. Nuclear Regulatory Commission 1 Region ll 101 Marietta Street, N.W.

Suite 2900 Atlanta, Georgia 30323 1

i Mr. D. R. Taylor ' I NRC Resident inspector North Anna Power Station Commissioner

! Department of Health Room 400 109 Governor Street Richmond, Virginia 23219 l

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COMMONWEALTH OF VIRGINIA )-

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COUNTY OF HENRICO )

l The foregoing document was acknowledged before me, in and for the County and Commonwealth aforesaid, today by W. L. Stewart who is Senior Vice President -

Nuclear, of Virginia Electric and Power Company. He is duly authorized to execute and file the foregoing document in behalf of that Company, and the statements in the document are true to the best of his knowledge and belie (.

Acknowledged before me this [ day of M k/A ,1973 My Commission Expires: ,

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• e ATTACHMENT 1 ,

DISCUSSION OF CHANGES VIRGINIA ELECTRIC AND POWER COMPANY

l Discussion of Change l Steam Generator inspection Scope Reduction North Anna Power Station Units 1 and 2 Introduction Pursuant to 10 CFR 50.90, Virginia Electric and Power Company is requesting a change to the Technical Specifications for North Anna Power Station Units 1 and 2.

The North Anna Technical Specifications (Table 4.4-1) currently require a minimum of two steam generators be inspected during the first inservice inspection (including the first inspection following steam generator replacement) and one steam generator be inspected during each of the following inservice inspections. However, inspection of more than one steam generator is considered to be unnecessary for essentially new steam generators after operating only one cycle. The purpcse of this proposed change is to reduce the minimum number of steam generators required to be opened for inspection during the first inspection (i.e., refueling outage) following a steam generator replacement.

Background

Surveillance Requirements 4.4.5.1 through 4.4.5.5 of the North Anna Power Station Units 1 and 2 Technical Specifications describe an inservice inspection program which is required to be performed in conjunction with the inservice inspection requirements of Section XI of the ASME Boiler and Pressure Vessel Code. These inspection programs serve to demonstrate the operability of the steam generator tubing.

The North Anna Unit 1 steam generators were replaced during the first quarter of 1993. Likewise, preliminary preparations are being made for replacement of the North Anna Unit 2 steam generators. The general purpose of steam generator replacement is to restore the integrity of the steam generator tubes to a level equivalent to new steam generators. In reality, replacement steam generator components incorporate a large number of design improvements which reflect the state-of-the-art" technology that currently exists for steam generator design. These design improvements are intended to improve the long-term maintainability and reliability of the repaired steam generators.

The replacement steam generator components for North Anna have been or are being manufactured using current codes and manufacturing techniques without compromising the requirements of the original code thus reflecting current technology in the areas of design, fabrication, and materials. Design changes and enhancements made to replacement steam generator components address the operating experience of the original steam generators and enhance the overall reliability and maintainability of the repaired steam generators. These enhancements do not adversely affect the mechanical or thermal-hydraulic performance of the repaired steam generators. Thus,

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'the replacement steam generators are considered superior to the original steam  ;

generators in terms of design and materials.

Specific Change i

The proposed change would modify Table 4.4-1 of Technical Specification 4.4.5.1 to reduce from two to one the minimum number of steam generators required to be inspected during the first refueling outage following a steam generator replacement.

The table has also been revised to remove those sections of the table not applicable to North Anna because of the total number of steam generators involved. These changes to the table _ in turn eliminate Note 2. Note 3 has subsequently been renumbered. (Elimination of the non-applicable information from the table is considered an editorial correction.)

The requirement to open and inspect two steam generators is considered unnecessary for the first inspection following steam generator replacement. A full baseline inspection is required to be performed prior to return-to-service and the quality of the replacement steam generators' design, fabrication, and materials is superior to the original steam generators. In addition, as evidenced by industry experience, no degradation is expected during the initial cycles of operation.

Although the proposed change reduces the number of steam generators required to be opened for inspection, the minimum number of tubes required to be examined during the inspection is not being changed, i.e., for one steam generator,9% of the tubes in that steam generator are required to be examined, and for two steam generators,4.5% of the tubes in each steam generator are required to be examined (9% total). Thus, the inspected tube population size has not changed.

The capability and reliability of primary-to-secondary leakage detection have been greatly increased since these Technical Specifications inspection requirements were originally imposed. Improvements in primary-to-secondary leak rate monitoring and trending capabilities provide added assurance that degradation of steam generator tubes will be detected.

Finally, approval of this change request will reduce radiation exposure of those personnel involved in opening and closing the steam generator manways and setting up the tube inspection equipment.

This proposed change does not affect or change any limiting conditions for operation (LCO) or any other surveillance requirements in the Technical Specifications and the Basis for the surveillance requirement remains unchanged.

Safety Significance The Technical Specifications requirement to inspect more than one steam generator is considered unnecessary following steam generator replacement. A full baseline inspection is required for the replacement components and the quality of the replacement steam generators' design, fabrication, and materials is superior to the original steam generators. As evidenced by industry experience, no degradation is

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' expected during the initial cycles of operation. No corrosion based degradation (i.e.,

PWSCC, ODSCC, pitting, thinning) similar to that experienced on older designs has l been observed to date on similar replacement generators. Industry inspection programs in general continue to exceed regulatory requirements and past problem areas continue to be monitored, in addition, primary-to-secondary leak rate monitoring .

and trending capability far exceeds the plant's original capabilities cod continues to. l improve.

Based upon the following justification, operation of the North Anna Power Station I having inspected only one steam generator during the first refue!!ng outage following steam generator replacement would not involve an unreviewed sofoty question.

1. The proposed inspection scope change does not increase the probability of occurrence of an accident previously evaluated. The performance history of Westinghouse steam generators has shown that degradation of the tubes is not significant in the early cycles of operation. In addition, the minimum number of tubes required to be inspected during the first refueling outago following steam generator replacement is not being changed.

2. The proposed inspection scope change does not increase the consequences of an accident previously evaluated. Any hypothetical tube leak or failure is bounded by the consequences of a postulated steam generator tube rupture event.

3. The proposed inspection scope change does not create the possibility of an accident of a different type than any previously evaluated. As noted previously, the effect of any hypothetical failure of a tube would be bounded by existing tube rupture analyses. The proposed change does not introduce any new failure mechanisms or postulated accident effects. Therefore, operation of the steam generators with this modified inspection schedule will not resuit in an accident previously not analyzed in the UFSAR.

4. The proposed inspection scope change does not increase the probability of occurrence of a malfunction of equipment important to safety previously evaluated.

Each of the replacement steam generators is manufactured and operated essentially identically. The minimum number of steam generator tubes required to be examined during the first refueling outage following steam generator replacement is not being changed. Thus, the size of the inspection population has not changed and there is no increase in the probability of occurrence of a steam generator tube leak or rupture. No other components or equipmont important to safety would be affected.

5. The proposed inspection scope change does not increase the consequences of a malfunction of equipment important to safety previously evaluated. As stated in items 1,2, and 3 above, the reduction in the number of steam generators required to be opened during the first refueling outage following steam generator replacement does not increase the probability or consequences of any event or accident in excess of the effects due to the rupture of a steam generator tube.

Current UFSAR analysis results remain bounding.

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' 6. The proposed inspection scope change does not create the possib!!ity of a malfunction of equipment important to safety of a different type than any previously l evaluated. Overall steam generator tube bundle integrity and leaktightness continue to be required during all plant operating conditions. The Technical i Specifications inservice inspection program continues to sample the steam l generator tubes to assure their condition.

7. The proposed inspection scope change does not reduce the margin of safety as defined in the basis for any Technical Specification. The margin of safety with respect to sampling inspections of tubes continues to provide assurance of tube bundle integrity. Nandestructive examination of the same number of steam generator tubes is still required - only the number of steam generators required to be opened is changed.

Based on the above evaluation, reducing the minimum number of steam generators required to be opened during the first refueling outage following steam generator replacement will not adversely affect the safe operation of the steam generators or the plant. Therefore, this regulatory requirement reduction for the North Anna Units 1 and 2 steam generators does not result in an unreviewed safety question as defined in the criteria of 10 CFR 50.59.

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