ML20148U329

Safety Evaluation Denying Relief Request 3-ISI-1.Based on Review,Nrc Concludes That Licensee Does Not Have Sufficient Basis for Relief from Code Required Successive Exam

ML20148U329
Person / Time
Site:	Browns Ferry
Issue date:	07/08/1997
From:	NRC (Affiliation Not Assigned)
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ML20148U304	List: ML20148U329
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NUDOCS 9707100157
Download: ML20148U329 (8)

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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION OF RE0 VEST FOR RELIEF 3-ISI-1 TENNESSEE VALLEY AUTHORITY I BROWNS FERRY NUCLEAR PLANT UNIT 3 DOCKET NO. 50-296

1.0 INTRODUCTION

The Technical Specifications (TS) for Browns Ferry Nuclear Plant (BFN), Unit 3 states 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'(B&PV) Code l 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). The 10 CFR 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.

Pursuant to 10 CFR 50.55a(g)(4), ASME Code Class 1, 2, and 3 components ,

(including supports) shall meet the requirements, except the design and access '

provisions and the pre-service examination requirements, set forth in the ASME Code,Section XI, " Rules for Inservice Inspection of Nuclear Power Plant Components," to the extent practical within the limitations of design, geometry, and materials of construction of the components. The regulations require that inservice examination of components and system pressure tests ,

conducted during the first ten-year interval and subsequent intervals ccmply i with the requirements in the latest edition and addenda of Section XI of the l ASME Code incorporated by reference in 10 CFR 50.55a(b) twelve months prior to '

the start of the 120-month interval, subject to the limitations and i modifications listed therein. The applicable edition of Section XI of the ASME Code for the BFN Unit 3, second ten-year inservice inspection (ISI) interval is the 1989 Edition.

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Pursuant to 10 CFR 50.55a(g)(5), if the licensee determines that conformance l with an examination requirement of Section XI of the ASME Code is not I practical for its facility, information shall be submitted to the Commission I in support of that determination e d a request made for relief from the ASME ,

Code requirement. After evaluatior. 4 the determination, pursuant to I 10 CFR 50.55a(g)(6)(1), the Commissiv., may grant relief and may impose alternative requirements that are determined to be authorized by law, will not ENCLOSURE 1 9707100157 PDR 970708 Q ADOCK 05000296 PDR i

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! Mr. Oliver D. Kingsley, Jr. BROWNS FERRY NUCLEAR PLANT  ;

l Tennessee Valley Authority l l

Cc' l Mr. O. J. Zeringue, Sr. Vice President Mr. Timothy E. Abney, Manager '

Nuclear Operations Licensing,and Industry Affairs

. Tennessee Valley Authority Browns Ferry Nuclear Plant 6A Lookout Place Tennessee Valley Authority 1101 Market Street Chattanooga, TN 37402-2801 l Mr. Jack A. Bailey, Vice President i Engineering & Technical Services I Tennessee Valley Authority )

6A Lookout Place l 1101 Market Street I Chattanooga, TN 37402-2801 l

Mr. C. M. Crane, Site Vice President i Browns Ferry Nuclear Plant i Tennessee Valley Authority P.O. Box 2000 Decatur, AL 35609 General Counsel Tennessee Valley Authority ET 10H 400 West Summit Hill Drive Knoxville, TN 37902 Mr. Raul R. Baron, General Manager l Nuclear Assurance and Licensing Temessee Valley Authority 4J Blue Ridge 1101 darket Street 1

Chattanooga, TN 37402-2801 Mr. Masoud Bajestani, Plant Manager l Browns Ferry Nuclear Plant l Tennessee Valley Authority P.O. Box 2000 Decatur, AL 35609 Mr. Pedro Salas, Manager Licensing and Industry Affairs Tennessee Valley Authority 4J Blue Ridge 1101 Market Street '

Chattanooga, TN 37402-2801

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endanger life, property, or the common defense and security, and are otherwise

'in the public interest, giving due consideration to the burden upon the licensee that could result if the requirements were imposed. q In a letter dated January 22, 1997, Tennessee Valley Authority (licensee), I l submitted to-the NRC its Second Ten-Year Inservice Inspection Interval Program Plan Request for Relief 3-ISI-1, regarding successive examination requirements for BFN Unit 3. .

2.0 EVALUATION The staff, with technical assistance from its contractor, the Idaho National Engineering and Environmental' Laboratory (INEEL),' has evaluated the information provided by the licensee in support of its Second Ten-Year l Inservice Inspection Interval Program Plan Request for Relief 3-ISI-l for-BFN Unit 3. Based on the information submitted, the staff adopts the contractor's conclusions and recommendations presented in the enclosed Technical Letter Report (TLR).

For Request for Relief 3-ISI-1,Section XI, IWB-2420(b), Successive Inspections When Flaw or Relevant Conditions are Evaluated and Qualify for  :

Continued Service, requires that if flaw indications or relevant conditions are evaluated in accordance with IWB 3132.4 or IWB-3142.4, respectively, and the component qualifies for continued service, the areas containing such flaw indications or relevant conditions shall be reexamined during the next three inspection periods listed in the schedules of the inspection programs of IWB-2410.

The licensee ~ requested relief from the successive examination requirements for -  !

' ten shell weld indications and five shell-to-flange indications exceeding the i acceptance criteria of the Code. The flaws were qualified for. continued .

service in accordance with IWB-3132.4. The licensee has proposed to perform l ultrasonic examination of the areas containing the subject indications during -

the third period of tiie'second interval (Cycle 11) in conjunction with the  !

required RPV shell weld examination.

During the reactor pressure vessei examinations at the end of the first ,

inspection interval, ten rejectable subsurface flaws in the reactor shell welds and five rejectable subsurface flaws in the flange-to-shell weld were  ;

identified. As allowed by the Code, the licensee performed fracture analyses on these flaws, which showed them to be acceptable for continued service. In ,

conjunction with the fracture analysis calculations, the licensee determined l that continued operation is justified for up to 12 effective full power years. .

Based on this. calculation, the licensee proposes .to reexamine the subject l flaws in the third period of the next 10-year inservice inspection, i.e., the Cycle.11 outage.

IWB-2420, Successive Inspections, requires that when flaws are evaluated and qualified as acceptable for continued service, the areas containing such flaw

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indications or relevant conditions be reexamined during the next three inspection periods. This reexamination must confirm flaw stability' and verifies that the. assumptions used in the fracture analysis were valid.

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. Based on the information the licensee has presented, the staff has concluded  !

the following i

1) The number of rejectab1e flaws is significant and the flaws require continued surveillance.

2) The licensee has not validated the fracture analysis by subsequent l examinations to verify that the subject fla'ws are not growing beyond l calculated projections.

, 3) An operating window of 12 effective full power years, as determined by calculation, is not an acceptable margin for quality and safety.

4) Implementation of. proposed Code Case N-526, Alternate Rules for Successive Inspections of Class 1 and 2 Vessels, which was inciuded l in the licensee's discussion on justification for granting relief, is not acceptable because this Code case has not been reviewed and approved by the staff.

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3. CONCLUSIONS The staff has reviewed the information provided by the licensee in support of Relief Request 3-ISI-1. Based on its review, the staff concludes that the licensee does not have a sufficient basis for relief from the Code-required successive examinations. Therefore, relief is not authorized.

Principal Contributcr: 1. McLellan i Dated: Jaly 8,1997 i

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. TECHNICAL LETTER REPORT ON THE SECOND 10-YEAR INSERVICE INSPECTION INTERVAL RELIEF REQUEST 3-151-1 TENNESSEE VALLEY AUTHORITY I BROWNS FERRY NUCLEAR PLANT. UNIT 3 DOCKET NUNBER 50-296

1.0 INTRODUCTION

By letter dated January 22, 1997, the licensee submitted the Browns Ferry Nuclear Plant, Unit 3, second 10-year interval inservice inspection program.

This Technical Letter Report contains the expedited evaluation of Relief Request 3-ISI-1. The Idaho National Engineering and Environmental Laboratory (INEEL) staff has evaluated the subject request for relief in the following section.

I 2.0 EVALUATION The Code of record for the Browns Ferry Nuclear Plant, Unit 3, second 10-year interval is the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code,Section XI, 1989 Edition. The information provided by the licensee in support of the request has been evaluated and the basis for disposition is documented below.

2.1 Reauest for Relief 3-ISI-1.Section XI. IWB-2420(b). Successive Inspections When Flaw or Relevant Conditions are Evaluated and Oualify for Continued Service 4

Code Reauirement: Section XI, IWB-2420(b) requires that "If flaw indications or relevant conditions are evaluated in accordance with IWB-3132.4 or IWB-3142.4, respectively, and the component qualifies for continued service, the areas containing such flaw indications or relevant conditions shall be reexamined during the next three inspection periods listed in the schedules of the inspection programs of IWB-2410."

ENCLOSURE 2

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1 L Licensee's Code Relief Reauest: The licensee requested relief from the successive examination requirements for ten shell weld indications and five shell-to-flange indications exceeding the acceptance criteria of the Code. The flaws were qualified for continued service in accordance

with IWB-3132.4.

4 Licensee's Basis for Reauestina Relief (as stated): l l " Accessible RPV shell welds were ultrasonically examined from the vessel inside surface utilizing the General Electric (GE) reactor inspection GERIS 2000 automated scanning system and from accessible areas on the )

vessel outside surface using manual techniques in areas with limited or i

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no accessibility from the inside surface. The examination identified '

fifteen ~(15) subsurface indications which exceeded IWB-3500 criteria, i but were evaluated to meet the criteria of IWB-3600 for continued i operation. Calculation MD-Q3001-940005 - evaluated the RPV indications  !

and determined that operation was justified for up to 12 effective full '

power years (EFPY). The 12 EFPY corresponds with the performance of the re-examination of these indications during the Unit 3 cycle 11 outage. j It was also determined that the margin of safety, based on the maximum '

IWB-3600 allowable, is greater than 5:1. l l

"The BWR Vessel and Internals Project Beltline Team, "BWR Reactor Pressure Vessel Shell Weld Inspection Recommendations (BWR VIP-05)", i EPRI #TR-105697, Section 11, submitted to NRC for review on September 28, 1995, summarizes the probability for growth of extensive subsurface cracking as negligible. The referenced evaluation recommended the inspection scope be reduced from essentially 100% of the circumferential and longitudinal seam welds to 50% of the longitudinal seam welds and no required examination'of circumferential shell welds (Item #1.10). This  ;

reduction of inspection scope is achieved while maintaining a failure probability two orders of magnitude below the NRC stated safety goal for reactor failure of 4X10-5 in 40 years.

The cost associated with each of the successive examinations is estimated to be in the-range of $1.5 to $2.0 million dollars. The combined cost for performance of successive examinations would be approximately $3.0 to $4.0 million dollars.

Licensee's Proposed Alternative Examination (as stated):

" Perform ultrasonic examination of the areas containing the subject indications during the third period of the second interval (cycle 11) in conjunction with the required RPV shell weld examination.  !

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Evaluation: During the reactor pressure vessel . examinations at the end  !

of the first inspection interval, ten rejectable subsurface flaws in the  !

reactor shell welds and five rejectable subsurface flaws in the flange- l to-shell weld'were identified. As allowed by the Code, the licensee  ;

performed fracture analyses on these flaws, which showed them to be acceptable for continued service. In conjunction with the fracture-analysis calculations, the licensee determined that continued operation-I l 1s justified for up to 12 effective full power years. Based on this  ;

calculation, the licensee proposes to reexamine the subject flaws in the ,

I third period of the next 10-year inservice inspection, i.e., the '

Lycle 11 outage.

IWB-2420, Successive Inspections, requires that when flaws are evaluated and qualified as acceptable for continued service, the areas containing such flaw indications or relevant conditions be reexamined during the i next three inspection periods. The reexamination confirms flaw stability and verifies that the assumptions used in the fracture analysis were valid. ,

~ Based on the information the licensee has presented, the INEEL us  ;

concluded the following:

1) The number of rejectable flaws is significant and the flaws require l

-continued surveillance.

2) The licensee has not validated the fracture analysis by subsequent examinations to verify that the subject f1aws are not growing beyond i calculated projections.

3) An operating window of 12 effective full power years, as determined by calculation, is not an acceptable margin for quality and safety.

4)_ Implementation of proposed Code Case N-526, Alternate Rules for Successive Inspections of Class 1 and 2 Vessels, which was inc1uded in the licensee's discussion on justification for granting relief, l

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.- is not acceptable b cause this Code case has, not been reviewed and approved by the NRC Staff.

3.0 CONCLUSION

, The INEEL staff has reviewed.the information provided by the licensee in support of Relief Request 3-ISI-1. Based on this rev.iew, it has been j determined that the licensee does not have a sufficient basis for relief from the Code-required successive examinations. Therefore, it is recommended that relief be denied.

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