ML20134N712

Safety Evaluation Accepting Relief Request 96-04 for Plant

ML20134N712
Person / Time
Site:	Oconee
Issue date:	02/20/1997
From:	NRC (Affiliation Not Assigned)
To:
Shared Package
ML16141B151	List: ML20134N712
References
NUDOCS 9702240385
Download: ML20134N712 (6)

Text

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P Ef j  % UNITED STATES s* j NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 10666 4 001

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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION THIRD TEN-YEAR INTERVAL INSERVICE INSPECTION PROGRAM PLAN REQUEST FOR RELIEF NO. 96-04 FOR DUKE POWER COMPANY OCONEE NUCLEAR STATION. UNIT 1 DOCKET NO. 50-269

1.0 INTRODUCTION

The Technical Specifications for Oconee Nuclear Station, Unit 1, state that the inservice inspection of the American Society of Mechanical Engineers (ASME) Code Class 1, 2, and 3 components shall be performed in accordance with Section XI of the ASME Boiler and Pressure Vessel Code (ASME Code) and applicable Addenda as required by 10 CFR 50.55a(g), except where specific written relief has been granted by the Commission pursuant to 10 CFR 50.55a(g)(6)(1).

Title 10 of the Code of Federal Reaulations (10 CFR) Section 50.55a(a)(3) states that alternatives to the requirements of paragraph (g) may be used, when authorized by the NRC, if (i) the proposed alternatives would provide an acceptable level of quality and safety or (ii) compliance with the specified requirements would result in hardship or unusual ' difficulties without a compensating increase in the level of quality and safety. The applicable edition of Section XI of the ASME Code for Oconee Nuclear Station, Unit 1, third 10-year inservice inspection (ISI) interval is the 1989 Edition.

In a letter dated August 5,1996, Duke Power Company (DPC or licensee) submitted to the NRC Relief Request No. 96-04 and requested relief under the provisions of 10 CFR 50.55a(a)(3)(ii) for its Oconee Nuclear Station, Unit 1.

The licensee is seeking relief to the Code-required preservice examination on mechanical systems at the upgraded Keowee Hydro Station Units 1 and 2. The upgrade of the Keowee Project was initiated by DPC in order to improve Keowee systems in response to NRC Electrical Distribution Systems Functional Inspections and Self-Initiated Technical Audits that were performed from 1992 to 1994. Several Keowee mechanical systems have been upgraded to DPC Piping Class F as a result of the Keowee Project. Upgrading Keowee mechanical systems to DPC Piping Class F resulted in application of additional, more restrictive requirements such as those contained in the ASME Code,Section XI and 10 CFR Part 50, Appendix B. ASME Section XI requires retention of documentation of preservice examinations performed on mechanical systems in accordance with the applicable construction codes. Since Keowee mechanical systems were not originally constructed under these requirements, little or no 9702240385 970220 PDR ADOCK 05000269 P PDR

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records of preservice examinations exist for Keowee mechanical systems. In i

L order to provide records DPC would have to perform a new preservice examination of the affected Keowee systems and, thus, obtain the Code-required j documentation. Performing new preservice examination on the upgraded Keowee systems would result in hardship or unusual difficulties without a 3' compensating increase in the level of quality and safety because of the l following reasons: (a) reduced availability of the emergency power source for Oconee Nuclear Station; (b) preservice examinations would have to be performed i

' on the systems prior to embedment in concrete (since much of the piping in the station have been embedded, it would not be practical to perform these inspections); and (c) the large number of joints in the system would require

! excessive time and resources to inspect.

I 2.0 EVALUATION 4 i

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I The Code of record for the Oconee Nuclear Station, Unit 1, 10-year inservice )

inspection interval is the 1989 Edition of the American Society of Mechanical

! Engineers (ASME) Boiler and Pressure Vessel Code (ASME Code),Section XI. The '

! information provided by the licensee in support of the request for relief from

Code requirements has been evaluated by the NRC staff and the results of the

review are documented below.

[ A. Reauest for Relief 96-04. Keowee Hydro Station Units 1 and 2

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i Gode Reauirement: ASME Code,Section XI, Paragraph IWA-6330 Construction Records requires that records are retained in accordance with the

applicable construction code. Part 50 of 10 CFR, Appendix B, Criterion j

XVII requires that sufficient records are maintained to furnish evidence

of activities affecting quality. 1 1

Licensee's Code Relief Renuest: The licensee requested relief from i

performing preservice examination on seven newly upgraded systems at the 3

Keowee Hydro Station Units 1 and 2. The seven systems were identified as follows: (1) Keowee Hydro Station Governor Oil System (OG); (2) Keowee Hydro Station Turbine Guide Bearing 011 System (GBO); (3) Keowee Hydro  ;

Station Turbine Sump System (TS); (4) Keowee Hydro Station Turbine Generator Cooling Water System (WL); (5) Keowee Hydro Station Governor Air ,

i System (AG); (6) Keowee Hydro Station Spiral Case; and (7)- Keowee Hydro  ;

Station Air Circuit Breaker Air System (AB). These systems were -

originally constructed under the rules of USAS B31.1.0 piping code July 1967 Edition. The spiral case was constructed under the rules of ASME Section VIII, 1965 Edition, Subsection UW. The above listed systems were subsequently upgraded and reclassified as being ASME Code,Section XI, ISI Class 3/DPC Class F systems.

Licensee's Basis for Reauestino Relief: (as stated)

Reference Code Requirement that has been determined to be excessively burdensome:

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USAS B31.1.0 Power Piping Code (7/67), Section 136, including

Table 136.5.1. This section requires piping installations to be inspected prior to service to the extent necessary to assure compliance with engineering design, and with the material, l fabrication, assembly, and test requirements of the Code.

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' ASME Boiler and Pressure Vessel Code Section XI, 1989 Edition; with no addenda, Article IWA-2411, Preservice Inspection. This section requires that the preservice inspection plan comply with p the adopted Code 36 months prior to the docket date of the

construction permit.

ASME Boiler and Pressure Vessel Code Section XI, 1989 Edition; 3 with no addenda, Article IWD-2200. This section states that all

[ examinations required by the Article, except pressure retaining

components up to the first isolation valve (Item D2.10 of 1 Examination Category D-B, Table IWD-2500-1), shall have a preservice examination prior to initial plant startup.

1 In accordance with 10 CFR 50.55a(a)(3)(ii), this request for i relief presents the significant level of hardship, without a

{ compensatina increase in the level of quality or safety, which t

would 1,e incurred as a result of performing preservice examinations for Keowee Hydro Station. IWA-2411 and IWD-2200 requirements cannot be met since Keowee Hydro Station was

constructed and operated prior to the existence of ASME Section

XI.

Prior to June 1992, there were no ISI Class assignments for the subject Keowee Hydro Station systems. In order to meet the requirements of USAS B31.1.0, every joint in the station would be required to be examined. Performance of preservice examinations on the Keowee mechanical systems will result in excessive burden for the following reasons:

1) Reduces availability of the emergency pown source for Oconee Nuclear Station. The unavailable hours accrued to perform the tests would be such that NRC Station Blackout availability requirements would not be met. The systems would have to be isolated, drained, tested, and refilled to perform the test.

2) Accessibility for preservice examinations requires extensive destructive measures. Preservice inspections have to be performed on the systems prior to embedment in concrete. Since much of the piping in the station, as well as the spiral case, have been embedded, it is not practical to perform these inspections.

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3) The large number of joints in the systems requires excessive time and resources to inspect. There are seven systems listed 3

for this relief request. Each system listed for this relief request makes the ONS [0conee Nuclear Station) emergency power source unavailable when the system is removed from service.

Hundreds of joints would have to be inspected within 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> Technical Specification Limiting Conditions for Operability 0

s (LCO).

Preservice examinations were most likely performed for the Turbine Guide Bearing 011 System, the Governor Oil System, the 3 Governor Air System, the Turbine Sump Pump System, and the Turbine Generator Cooling Water System based on the Duke Power i Piping Specifications for Keowee. The specification for the '

hydraulic turbine and governors, KS-200, requires pressure  ;

testing of components and applicable NDE requirements such as  !

j 100% radiography of the spiral case. This documentation has not been found to date. The spiral case construction procedure calls  ;

for radiography in accordance with ASME Section VIII.

Licensee's Proposed Alternative: (as stated)

No alternate preservice examinations are proposed. The time frame involved in draining, testing, cleaning, and refilling systems normally containing oil or air to perform hydrostatic testing adversely affects availability of the emergency power source for Oconee Nuclear Station. USAS B31.1.0, 7/67 edition paragraph 137.1.2(a) states, "An initial service leak test and inspection is 1 acceptable when other types of tests are not practical or when leak tightness is conveniently demonstrable due to the nature of the service". The reliable operation of the station for  !

the past 24 years, the constant operator rounds which inspect for  ;

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leakage (OP/0/A/2000/043, Attachment 2), and the implementation of  !

the Inservice Inspection program in November 1995, provide assurance l that the piping systems can perform adequately under the Duke Piping .

Class F category. I Acceptability of proposed alternate testing with respect to the

level of quality and safety as well as public health and safety

All the safety related piping systems at Keowee Hydro Station were constructed under USAS B31.1.0. The spiral case was i

constructed under ASME Section VIII. The piping used at Keowee i Hydro Station will function as designed and is fully qualified for the conditions expected to be present at Keowee Hydro Station during and after an accident. This position is based on years of station operation without piping leakage, and load rejection testing and emergency starting which place J

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) the spiral case 'and operating systems in their most demanding conditions. Considerations in this qualification include material compatibility, pressure / temperature rating, and welding personnel ,

qualifications. For the piping systems, there is little difference

, in the testing requirements required by the construction codes as i compared to ASME Section XI. i i ,

1 The piping has provided reliable service for Keowee Hydro Station for i a period of 24 years. The placement of these piping systems into the ISI Class 3, Duke Power Piping Class F program will provide additional assurance with respect to the piping integrity.

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Not performing the code required preservice examinations does not l decrease the level of public safety, or any level of quality, '

associated ,with the operation of the systems at Keowee. The inservice reliability and increased level of planned inservice inspections provides an acceptable level of assurance for future operation.

NRC Staff Evaluation: The staff has reviewed the information provided in DPC's letter dated August 5,1996, in support of its Request for Relief No.

96-04, for Oconee Unit 1. DPC requested that seven mechanical systems at the Keowee Hydro Station be exempt from the required ASME Code preservice inspection examination because compliance with the Code requirements will result in hardship or unusual difficulty without a compensating increase in the level of quality and safety. The seven systems were identified as follows:

(1) Keowee Hydro Station Governor Oil System (OG); (2) Keowee Hydro Station Turbine Guide Bearing 011 System (G80); (3) Keowee Hydro Station Turbine Sump System (TS); (4) Keowee Hydro Station Turbine Generator Cooling Water System (WL); (5) Keowee Hydro Station Governor Air System (AG); (6) Keowee Hydro Station Spiral Case; and (7) Keowee Hydro Station Air Circuit Breaker Air System (AB). These systems were originally constructed under the rules of USAS B31.1.0 piping code July 1967 Edition. The spiral case was constructed under the rules of ASME Section VIII, 1965 Edition, Subsection UW. These systems were subsequently upgraded and reclassified as being ASME Code,Section XI, ISI Class 3/DPC Class F systems.

The upgrade of the Keowee Project was initiated by DPC in order to improve Keowee systems in response to NRC Electrical Distribution Systems Functional Inspections and Self-Initiated Technical Audits that were performed from 1992 to 1994. Upgrading the Keowee mechanical systems to DPC Piping Class F resulted in application of additional, more restrictive requirements-such as those contained in the ASME Code,Section XI and 10 CFR Part 50, Appendix B.

ASME Section XI requires retention of documentation of preservice examinations performed on mechanical systems in accordance with the applicable construction codes.

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' Since the Keowee mechanical systems were not originally constructed under 1 these requirements, little or no records of preservice examinations exist for

these systems. In order to provide records DPC would have to perform a new '

,' preservice examination of the affected Keowee systems and thus obtain the code-required documentation. Performing new sreservice examination on the upgraded Keowee systems would result in hards 11p or unusual difficulties i without a compensating increase in the level of quality and safety because of l the following reasons: (a) reduced availability of the emergency power source I

! for Oconee Nuclear Station; (b) preservice examinations would have to be l performed on the systems prior to embedment in concrete (since much of the piping in the station have been embedded), it is not practical to perform )

these inspections; and (c) the large number of joints in the system would

require excessive time and resources to inspect. In addition, the seven i I

piping systems have been incorporated into the Oconee Nuclear Station Unit 1 l l .ISI program.

The piping systems are now classified as DPC Piping Class F, ISI Class 3 and j all repairs, replacements, and modifications on these systems will be in accordance with the USAS B31.1.0, July 1967 Edition. The inservice examinations and testing will be done in accordance with ASME Section XI, 1989

! Edition. Further, the spiral case, which was constructed under ASME Section VIII rules, is now classified also as DPC Piping Class F, ISI Class 3.

Replacements, repairs, and modifications conducted on the spiral case will be i conducted in accordance with ASME Section VIII, 1965 Edition. The inservice i examinations and testing will be done in accordance with ASME Section XI, 1989 1 Edition. The implementation of ASME Code,Section XI, rules is in effect at

){ this time.

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3.0 CONCLUSION

The NRC staff has reviewed the licensee's submittal and concludes that the Code examination requirements are impractical for the seven Keowee systems included in Request for Relief No. 96-04, for Oconee Unit 1. The examinations i that were performed during the construction of the systems, the reliable  !

i operation of the station for the past 24 years, and the implementation of the

] Inservice Inspection program in November 1995 provide reasonable assurance of adequate structural integrity and safety.

The staff concludes that the upgraded piping systems at the Keowee Hydro Station can perform adequately under the ASME Code,Section XI, Class 3/ Duke l Piping Class F category and imposing the Code requirements on the facility would result in hardship or unusual difficulty without a compensating increase <

in the level of quality and safety and, therefore, relief is granted, pursuant  !

to 10 CFR 50.55a(a)(3)(ii) as requested, i Principal Contributor: George Georgiev  !

Date: February 20, 1997 i