ML20136H682

Safety Evaluation Granting Relief from Certain Inservice Testing/Insp Requirements Re Reactor Vessel Flange Ligaments,Reactor Coolant Pump Casing Internal Surfaces & Flange Bolts

ML20136H682
Person / Time
Site:	Farley
Issue date:	12/27/1985
From:	Office of Nuclear Reactor Regulation
To:
Shared Package
ML20136H676	List: ML20136H671 ML20136H682
References
TAC-59900, TAC-59901, NUDOCS 8601100441
Download: ML20136H682 (8)

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SAFETY EVALUATION FOR GRANTING OF RELIEF BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO INSERVICE TESTING REQUIREMENTS CERTAIN REACTOR VESSEL FLANGE LIGAMENTS, REACTOR COOLANT PUMP CASING INTERNAL SURFACES AND FLANGE BOLTS ALABAMA POWER COMPANY JOSEPH M. FARLEY NUCLEAR PLANT, UNITS NOS. 1 AND 2 DOCKET NOS. 50-348 AND 50-364 1

INTRODUCTION The Technical Specifications for the J. M. Farley Nuclear Power Plant Units 1 and 2 state that inservice examination of ASME B&PV Code Class 1, 2, and 3 components shall be performed in accordance with Section XI of the Code and applicable Addenda as required by 10 CFR 50.55a(g) except where specific written relief has been granted by the Commission. The examination program is based upon the requirements of the 1974 Edition and Addenda through the Summer of 1975. Certain requirements of this Edition and Addenda of Section XI are impractical to perform on older plants because of the plants' design, component geometry, materials of construction or the need for extensive temporary modifications and the resultant substantial radiation exposure to plant personnel.

In order to complete the first ten-year inspection interval at Joseph M. Farley Nuclear Plant Units 1 and 2 relief from certain Code inservice inspection requirements is required. 10 CFR 50.55a(g)(6)(1) authorizes the Commission to grant relief from those requirements upon making the necessary findings that the requirements are impractical to perform.

We had reviewed the licensee's first ten-year interval inservice inspection program plan and the requests for relief from certain requirements of the applicable ASME Code edition and addenda. We had provided a number of 8601100441 851227 PDR ADOCK 05000348 PDR

Safety Evaluations and had granted relief from examination requirements which we had determined to be impractical to perform at the Joseph M. Farley Nuclear Power Plant Units 1 and 2.

RELIEF REQUESTS-CODE CLASS 1

1. RELIEF IS REQUESTED FROM THE VOLUMETRIC EXAMINATION OF REACTOR VESSEL FLANGE LIGAMENT NUMBERS 1, 25, 26, 27, 41, 42, 43, 57 AND 58 (ITEM B1.9, CATEGORY B-G-1)

CODE EXAMINATION REQUIREMENT:

-f Table IWB-2600, Item Bl.9 and Table IWR-2500, Category B-G-1 require volu-metric examination of 100% of the ligaments between the threaded stud holes of the reactor vessel flange during each inspection interval.

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, LICENSEE'S BASIS FOR RELIEF:

To reduce the critical path outage time required to perform reactor vessel examinations and reduce the exposure of examination personnel, reactor vessel i

volumetricexaminations,includingexaminationoftheligaments(58 total) between the threaded stud holes, are performed utilizing a remote ultrasonic examination tool. For the purpose of safely removing and reinstalling the reactor vessel head, and positioning the remote examination tool, three guide studs are placed in the reactor vessel flange at stud hole Numbers 26, 42, i and 58. During the examination, these guide studs prevent the ultrasonic  !

transducers mounted on the remote tool arm from accessing the ligaments around  !

each guide stud as well as the ligaments between the stud holes on either

sideoftheguidestuds(Numbers 1,25,27,41,43and57). e i

PROPOSED ALTERNATIVE EXAMINATION:

The remaining 49 ligaments will be ultrasonically examined as required by the ASME Code,Section XI. I i

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7 EVALUATION To facilitate safe removal and reinstallation of the reactor vessel head and positioning of the remote reactor vessel examination tool, three guide studs 4 are installed in stud holes. During the ultrasonic examination perfomed by the remote tool, the guide studs prevent the ultrasonic transducers mounted on the remote tool am from accessing the ligaments around each guide stud as well as the ligaments between the stud holes on either side of the guide studs.

To date, 66% of the ligaments have been examined on both Units and no recordable indications have been found. Since the ligaments are located in the flange base material and, are not in the most highly stressed region of i the flange, the probability of any service induced degradation occurring in these areas is minimal. The examination of the listed ligaments is impractical i considering that performing the examination would require the " hands-on" examination by an inspector with a concomitant large increase in the inspector's radiation exposure.

CONCLUSION, Based upon the above evaluation, it is concluded that the code-required examination is impractical. Considering the burden that would be imposed on j the facility, the staff finds that performing the Code-required examinations j would not provide a comensurate gain in the safety of the plant. The examina-tions of the ligaments as performed and to be performed will provide assurance l of the structural integrity of the ligaments. Therefore the request for relief may be granted.

2. RELIEF IS REQUESTED FROM THE VISUAL EXAMINATION 0F THE REACTOR COOLANT PUMP ,

I CASING INTERNAL PRESSURE BOUNDARY SURFACES (ITEM B5.7 CATEGORY B-L-2)

CODE EXAMINATION 7EQUIREMENT:

l Table IWB-2600, Item B5.7 and Table IWB-2500, Category B-L-2 require visual  ;

examination of the internal pressure boundary surfaces of one tractor coolant I I

pump during each inspection interval.

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LICENSEE'S BASIS FOR RELIEF:

The ASME Code,Section XI pennits the visual inspection of the reactor coolant

! pump (RCP) internal pressure boundary surfaces to be perfonned on the same pump disassembled for the purpose of performing the required volumetric l examination of the pressure retaining casing welds. The RCP casings for Farley Nuclear Plant are one piece casings and therefore do not contain pressure retaining welds. Since the pump does not require disassembly for volumetric weld examination, the disassembly of a RCP solely for the purpose of visually examining the interior surface is impractical. The pump manufacturer (Westinghouse) neither recommends nor requires pump disassembly for the perform-ance of routine maintenance or inspections. If the RCP internals are removed, they would require complete disassembly because a gasket internal to the pump j

would need replacement as a result of relaxing the main flange bolts. It has been estimated that complete RCP disassembly and reassembly could require up to 15 days of critical path outage time to complete. Also, the radiation exposure, which is estimated at 50 man-rem, may limit access to and mobility in the containment for other routine refueling outage activities. An activity of this complexity, performed under adverse field conditions, could potentially result in handling damage which could degrade the RCP, In the absence of the need for volumetric weld examination and considering the hardship imposed by pump disassembly and potential for RCP degradation, the visual examination of the internal pressure boundary surface is not justified.

PROPOSED ALTERNATIVE EXAMINATION The exterior of the RCP casing will be visually examined during the RCS hydro-static pressure test required by IWB-5000. A visual examination, not to exceed once per interval, will be performed on the internal pressure boundary surface of one RCP as required by Item B5.7, Category B-L-2 f f maintenance or operational problems are encountered which require the removal and disassembly of the internals.

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EVALUATION The RCP casir.gs for Farley Nuclear Plant Units 1 and 2 are one piece casings and therefore do not contain pressure retaining welds. Since the pump does not require a volumetric weld examination, the disassembly of a RCP would be solely for the purpose of visually examining the interior surface. If the RCP internals are removed, they would require complete disassembly because a gasket internsi to the pump would need replacement as a result of relaxing the main flange bolts. An activity of this complexity, perfortned under adverse field conditions, could potentially result in handling damage which could degrade the RCP. The exterior of the RCP casing will be visually examined during the reactor coolant system (RCS) hydrostatic pressure test rtquired by IWB-5000. A visual examination, not to exceed once per interval, will be performed on the internal pressure boundary surface of one RCP if maintenance or operational problems are encountered which require the removal and dis-assembly of the internals. The visual examination of the interior of the pump casing is to determine whether unanticipated severe degradation of the casing is occurring due to phenomena such as erosion, corrosion or cracking. However, experience at other plants during examinations of pumps has not shown any significant degradation of casings. Therefore, we have previously granted relief from pump casing interior examinations at a number of nuclear power plants. The proposed alternate tests and examinations are reasonable substitutes for the code-required examination.

CONCLUSION Based upon the above evaluation, it is concluded that the Code-required examina-tions of the internal surfaces of the pump casings are impractical. It is further concluded that with the safety margins inherent in the basic pump design, the alternativt examiu tions discussed will provide the necessary assurance of the

,, structural integrity of th> pump casing. Therefore, the request for relief may be granted.

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3. RELIEF IS REQUESTED FROM REMOVAL OF THE REACTOR COOLANT PUMP MAIN FLANGE BOLTS FOR VOLUMETRIC AND SUPFACE EXAMINATIONS (ITEM B5.2 CATEGORY B-G-1) i CODE EXAMINATION REQUIREMENT:

During each inspection interval, Table IWB-2600, Item B5.2 and Table IWB-2500, Category B-G-1 require the performance of volumetric and surface examinations on 100% of the RCP main flange bolts, studs, nuts, threads, bushings and liga-ments, when the bolting is removed.

LICENSEE'S BASIS FOR RELIEF:

i Removal of the main flange bolts for examinations would require the removal t

! and complete disassembly of the RCP internals, because a gasket internal to the pump would need replacement as a result of relaxing the main flange bolts. The pump manufacturer (Westinghouse) neither recomends nor requires pump disassembly j for the performance of routine maintenance or inspections. The RCD casings for l Farley Nuclear Plant are one piece casings and therefore do not contain pressure retaining welds which require volumetric examination in accordance with the j ASME Code Section XI. Relief has been requested from the ASME Code required i visual examination of the RCP internal pressure boundary surfaces, to eliminate j

, the need for RCP disassembly. The basis for this relief, which is also appli- i i cable to the removal of the main flange bolts, is that the high level of radia-

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tion exposure, additional critical path outage time required to disassemble the t 4

pump and potential damage and degradation to the RCP, solely for the purpose of {

l perfoming inservice examination, is not justified.

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PROPOSED ALTE,RNATIVE EXAMINATION  !

. The RCP main flange bolting will be volumetrically and visually examined in >

j place in accordance with the ASME Code,Section XI, Items 85.1 and 85.3, Category B-G-1. Not to exceed once per interval, the main flange bolts, nuts, bushings, threads and ligaments of each pump will be examined when the l

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bolting is removed as required by Item 85.2. Category 3-G-1, if maintenance or operational problems are encountered which require the removal and disassembly of the RCP internals.

EVALUATION If maintenance or operational problems are encountered which require the removal of the main flange bolts and disassembly of the RCP internals, the bolts, nuts, bushings, threads and ligaments between the bolts for one pump (per inspection interval) will receive the volumetric and surface examinations in accordance with the ASME Code while the bolts are removed. Removal of the main flange bolts for the purpose of examination only would require the complete disassembly of the PCP internals, because a gasket internal to the pump would need replacement as a result of relaxing the main flange bolts. The main flinge bolting for all three Unit 1 RCPs and two Unit 2 RCPs have been volumetrically and visually examined in place as required by the ASME Code and no recordable indications have been found.

CONCLUSION We previously granted relief to perform the required examinations at such time as the pump is disassembled for maintenance. Considering the burden that would be imposed on the facility, the staff finds that performing the Code-required examination would not provide connensurate gain in the safety of the plant. The prior examination of the bolting and the proposed alternate exami-nations provide reasonable assurance of the structural integrity of the bolting.

Therefore, the request for relief may be granted.

SUMMARY

AND CONCLUSION Based on the review, the staff concludes that relief granted from the examina-tion and testing requirements and alternate methods imposed through this document give reasonable assurance of the component pressure boundary and w_________________-_-_. _ _ _ _ _ _ _ _ _ _ _ _ _ ._ _ _ _ _ _ _ _ _ _ _ . _ _ _ _ _ _ _

support structural integrity, that granting relief where the Code requirements are impractical is authorized by law and will not endanger life or property, or the comenon defense and security, and is otherwise in the public interest considering the burden that could result if they were imposed on the facility.

DATE: December 27, 1985 PRINCIPAL CONTRIBUTOR:

B. Turovlin 6

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