ML18064A743
| ML18064A743 | |
| Person / Time | |
|---|---|
| Site: | Palisades  |
| Issue date: | 05/02/1995 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML18064A742 | List: |
| References | |
| NUDOCS 9505090241 | |
| Download: ML18064A743 (4) | |
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UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION ALTERNATE CODE REQUIREMENTS FOR SECOND INTERVAL INSERVICE INSPECTION FOR
1.0 INTRODUCTION
CONSUMERS POWER COMPANY PALISADES PLANT DOCKET NO. 50-255 The Technical Specifications for Palisades Plant state that the inservice inspection {ISi) and testing 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 and applicable Addenda as required by 10 CFR 50~5i5ia(g), except where specific written relief has been granted by the Commission pursuant to 10 CFR 50.55a(g}(6)(i).
10 CFR 50.5Sa(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 50.5S~(g)(4}, ASME Code Class 1, 2, and 3 components
{including supports} shall meet the requirements, except the design and access provisions and the preserwice 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 IO-year interval and subsequent intervals comply with the requirements in the latest edition and addenda of Section XI of the ASME Code incorporated by reference in 10 CFR S0.55a(b} on the date 12 months prior to the start of the 120-month interval, subject to the limitations and modifications listed therein. The 1983 Edition, Summer 1983 Addenda, of Section XI is the applicable edition of the ASME Code for the Palisades Plant, second IO-year ISi interv~. The components (including supports} may meet the requirements set forth in subsequent editions and addenda of the ASME Code incorporated by reference iin 10 CFR 50.SSa{b}, subject to the limitations and modifications listed therefo and subject to Commission approval.
In a letter dated March 30, 1995, the licensee, Consumers Power Company, requested NRC approval to apply the 1989 Edition of Section XI of the ASME Code, as it applies to visual inspection of valves, so that it will not have to schedule a disassembly of one of the valves for the sole purpose of performing visual inspection of the valves' internal surfaces.
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2.0 EVALUATION 2.1 Licensee's Request The licensee's March 30, 1995, letter stated the following request:
"IO CFR 50.55a(g)(4)(iv) allows that inservice examinations of components may meet the requirements set forth in subsequent additions [sic] and addenda of the Code that the NRC has approved in 10 CFR 50.SSa(b), as long as all related requirements of the respective editions or addenda are met.
10 CFR 50.55a(b) now states that Section XI of the ASHE Code including Addenda through the 1988 Addenda and Editions through the 1989 Edition have been approved for use.
The 1989 Edition of Section XI of the Code has been revised to require the internal surface inspection of one valve in each grouping only when a valve is disassembled for maintenance, repair or volumetric evaluation.
The purpose of this letter is to request NRC approval to apply the 1989 Edition of Section XI of the ASME Code, as it applies to visual inspection of valves, so that we will not have to schedule a disassembly of one of the valves for the sole purpose of performing visual inspection of the valves' internal surfaces.
We believe that compliance with the valve disassembly and internal surface inspection requirements of the second interval Code Record for one valve, would result in hardship without a compensating increase in the level of quality and safety."
2.1.1 Licensee's Component Identification Components identified for this relief include M0-3015 and M0-3016.
These valves are 12" Velan gate valves which isolate the primary coolant system from shutdown cooling.
2.1.2 ASME Code,Section XI, Second Interval Requirements The 1983 Edition Summer 1983 Addenda, Table IWB-2500-1 Category B-M-2, Item Number 812.50 requires a visual {VT-3) examination of the internal surfaces for valves exceeding 4-inch nominal pipe size. This examination is limited to at least one valve within each group of valves that are of the same construction, design, and manufacturing method and that perform a similar function in the system.
2.1.3 Licensee's Proposed Alternative Examination The licensee proposed no alternative examination.
2.1.4 Licensee's Basis The licensee's March 30, 1995, letter provided the following basis:
"All other valve groups and pump internal examination requirements were met during the second interval using Section XI 1983 Edition Summer 1983
e e Addenda.
Palisades will be using the Section 1989 Edition only for valves M0-3015 and M0-3016.
We have reviewed the 1989 Edition of Section XI and find that there are no other related sections of the Code that need to be considered for implementation when using the later edition valve internal visual inspection requirements.
We also have reviewed section 10 CFR 50.55a(b) and find no limitations or modifications subject to the use of this valve internal visual inspection requirement.
These Velan gate valves were constructed under ASTM [American Society for Testing and Materials] specification Al82 and the body material is Stainless Steel Grade F316.
The F316 material is made of 16Cr-12Ni-2Mo with a 30 KSI Yield Strength and a 75 KSI Tensile Strength. This material is suited for the expected service conditions and will not degrade in service.
Both M0-3015 and M0-3016 were disassembled during the first inspection interval and no indications were identified.
We have no evidence to suggest that the conditions of these valves has degraded since those inspections.
These valves can only be disassembled during a full core off-load with shutdown cooling stopped and the primary coolant system drained. While the reactor will be defueled during a portion of the 1995*refueling outage, inspection of one of the two valves is still not warranted in light of the impact on the outage schedule and the radiation dose that would be accumulated.
Since these two valves isolate the shutdown cooling system from the primary coolant system and primary coolant system leakage rate is monitored very closely, any leakage through these valves to the shutdown cooling system would be readily identified.
The valve body welds on M0-3016 will be ultrasonically inspected from the exterior surface during the upcoming refueling outage. This examination will require removal of insulation from the valve body and will identify any internal defects in the weld and heat affected zone and will allow a visual inspection of the external surfaces.
These valves are part of our motor-operated valve program and are scheduled to have their motors replaced during the next refueling which will be followed by Votes static diagnostic testing. This testing will provide assurance that the valve stem and disc are intact and the valve is fully functional.
Based on the above, we believe that disassembling either M0-3015 or M0-3016 for the sole purpose of performing a visual valve internal surface examination would result in a hardship or unusual difficulty without a compensating increase in the level of quality and safety."
2.I.5 Evaluation The licensee had scheduled for examination each group of valves during the second inspection interval so that the VT-3 examination could be performed in conjunction with any scheduled maintenance activity where disassembly of a valve body in each group was required. Approval is required for the second IO-year ISi interval because the. valves in this group have not had a VT-3 examination since they have not been disassembled during the second IO-year inspection interval for a scheduled maintenance activity.
In addition, the second IO-year ISi interval ends following completion of the I995 refueling outage.
The outage is scheduled to begin late May 1995 and is the last outage of the second IO-year ISi interval. The 1995 outage would be the last opportunity to examine the subject valves; however, the valves are.not scheduled for maintenance this outage.
- Disassembly of the subject valves for the sole purpose of visual examination of the valve body internal surfaces is a major effort and requires many manhours from skilled maintenance and inspection personnel.
In addition to the possibility of damage to the valve from a disassembly, personnel could receive high radiation exposure.
The visual examination is performed to determine if unanticipated degradation of the valve body is occurring due to phenomena such as erosion, corrosion, or cracking.
However, previous examinations of similar valv~s at other plants has not shown any significant degradation of valve bodies.
Consumer Power Company has stated that during the third IO-year inservice ~nspection interval the Code-required visual shall be scheduled the first time disassembly of a valve body in this group is required during a normal maintenance *activity as permitted by the Code of record for the third IO-year interval. The applicable Code for the third 10-year interval is the 1989 Edition.
The I989 Edition of the ASME Code has eliminated disassembly of valves for the sole purpose of performing examinations of the internal surfaces and states that the internal surface visual examination requirement is only applicable to valves that are disassembled for reasons such as maintenanc~ or repair. The concept of visual examination of the internal surfaces of the valve body, when the valve is disassembled for maintenance is acceptable. Since no major problems have been reported in the industry with regard to these types valve bodies, the licensee's proposal will provide adequate assurance of the continued inservice structural integrity of the subject valves.
3.-0 CONCLUSIONS Based on industry experience, the licensee's proposal to use a later portion of the Code will provide adequate assurance of the continued inservice structural integrity of the subject valves. Pursuant to 10 CFR 50.55a(g)(4}(iv), approval is authorized to apply the 1989 Edition of Section XI of the ASME Code as it applies to visual inspection of valves M0-30I5 and M0-30I6, provided that all related requirements are met, as will be confirmed through inspections.
Principal Contributor:
M. Gamberoni Date:
May 2, 1995