ML20086K507
| ML20086K507 | |
| Person / Time | |
|---|---|
| Site: | North Anna  |
| Issue date: | 12/04/1991 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20086K492 | List: |
| References | |
| RTR-REGGD-01.083, RTR-REGGD-1.083 NUDOCS 9112130145 | |
| Download: ML20086K507 (5) | |
Text
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NOS. 151 AND 135 TO FACILITY OPERATING llCENSE N05. NPF-4 AND NpF-7 VIRGINIA ELECTRIC AND POWER C0ftPANY OLD DOMIN10N ELECTRIC COOPERATIVE NORTH ANNA POWER STATION, UNITS NO. 1 AND NO. 2 DOCKET NOS. 50-338 AND 50-339
1.0 INTRODUCTION
By letter dated October 3,1991, the Virginia Electric and Power Company (the licensee) proposed a change to the Technical Specifications (TS) for the North Anna Power Station, Units No. 1 and No. 2 (NA-1&2). The change would revise the NA-1&2 TS 4.4.5.4.a.9 which provides preservice inspection (baseline eddy current examination) requirements for steam generator (SG) tubing by removing the restriction that the preservice inspection be performed after the field hydrostatic pressure test. The proposed change is similar to and consistent
.with the baseline inspection philosophy already approved by the NRC for other operating nuclear power plants.
This proposed TS change affects surveillance requirement 4.4.5.4.a.9.
The phrase, "after the field hydrostatic test and prior to initial POWER OPERATION," found in the current second sentence of that paragraph would be deleted. Subsequent to deletion of this phrase, surveillance requirement 4.4.5.4.a.9 would read as follows:
"Preservice inspection means an inspection of the full length of each tube in each steam generator performed by eddy current techniques prior to service to establish a baseline condition of the tubing. This inspection shall be performed using the equipment and techniques expected to be used during subsequent inservice inspection."
NRC Regulatory Guide 1.83, Revision 1, describes a method acceptable to the NRC staff for implementing General Design Criteria (GDC) 14, 15, 31, and 32 of Appendix A to 10 CFR Part 50 by reducing the probability and consequences of SG tube failures through periodic inservice inspection for early detection of defects and deterioration.
GDC-14 " Reactor Coolant Pressure Boundary," and GDC-31, " Fracture Prevention of Reactor Coolant Pressure Boundary," require that the reactor coolant pressure boundary have an er.tremely low probability of abnormal leakage, of rapidly propagating failure, and of gross rupture. GDC-15, " Reactor Coolant System Design," requires that the reactor coolant system be designed with sufficient margin to ensure that the design conditions of the reactor coolant l
9112130145 911204 PDR ADOCK 05000338 P
a.
pressure boundary are not exceeded during any condition of normal operation, including anticipated operational occurrences.
Furthermore, GDC-32,
" Inspection of Reactor Coolant pressure Boundary," requires that components which are part of the reactor coolant pressure boundary be designed to permit periodic inspection and testing of critical areas to assess their structural and leak-tight integrity.
The NA-1&2 TS urveillance requirements 4.4.5.1 through 4.4.5.5 describe an augmented it
~vice inspection program which is required to be performed in conjunction <1ch the inservice inspection requirements of Section XI of the ASME Boiler and Pressure Yessel Code. The combination of these inspection prugrams serve to demonstrate the operability of the SGs.
2.0 DISCUSSION The NA-1&2 TS surveillance requirement 4.4.5.4.a.9 requires that an inspection of the full length of each tube in each SG be performed by eddy current techniques prior to service to establish a baseline condition of the tubing.
This surveillance requirement further specifies that the preservice inspection be performed after the field hydrostatic test prior to initial power operation using the equipment and techniques expected to be used during subsequent inservice inspection. The purpose of the proposed change is to revise the TS requirement for preservice inspection of SG tubes by removing the unnecessary restriction that the preservice inspection be performed after the field hydrostatic pressure test.
The requested TS change continues to conform with the ASPE Section XI requirements.
ASME Section XI allows that shop-performed examinations may serve in lieu of the on-site preservice exam;,iations provided that (1) the examinations are conducted under conditions and with equipment and techniques equivalent to those that are expected to be employed for subsequent inservice examinations, and (2) the shop examination records are documented and identified in a forn consistent with Code requirements, in addition, the Code allows that these preservice examinations may be performed either prior to or following the system hydrostatic pressure tests.
Regulatory Guide 1.83, Revision 1, provides the NRC's regulatory positions on the content and establishment of an inservice inspection program for SG tubing.
Regulatory position C.3.a of Regulatory Guide 1.83, Revision 1, directs that all tubes in the SGs should be inspected by eddy current or alternative techniques prior to service to establish a baseline condition of the tubing. The regulatory position does not specifically require that this baseline inspection be performed following any field hydrostatic pressure test.
In fact, the discussion of Regulatory Guide 1.83, Revision 1, acknowledges the use of the usual shop examination of tubing as an adequate baseline examination.
F1L' g There is substantial benefit to performing the preservice inspection of tha tubing of the SGs in the vendor's shop in lieu of post-installation inspection.
These benefits include:
1.
ALARA. Although an in-place preservice inspection nf the SG tubes could be performed near the end of the associated replacement outage, many of the surrourding components will still be radiologically activated and mi<y areas may still be contaminated, uasce, the dose to the inspect personnel would be reduced by erforming the inspection *
- cor's shop.
Even considering rthe scope of the preservin
,t~
, Tnd the outage-related 3 " 'O man-rem savings efforts used to reduce doc o
would be expected by perfon
- na t an in the shop in lieu of in-place at NA-1, 2.
Ease of inspection. The shop D is Dasier to conduct than the in-place inspection in u
- ton equipment can be positioned in close proyimity to tie ojie ossentlies and access by personnel is facilitated.
3.
Reduced outage time. The inspection can be performed in the shop at a convenient time after the shop hydrostatic pressure test without impact on the celivery schedule. However, for each SG inspected in the field, it is expected to take approximately 7 days to complete the inspection and an additional 2 days to complete the data analysis.
If performed during the replacement outage with the SGs in-place, the majcrity of this time would be on the critical path of the outage schedule.
By eliminating this inspection activity from the schedule, the outage duration could be reduced.
The augmented TS surveillance requirements for inspection of the SG tubes further ensure that the structural integrity of this portion of the reactor coolant system will be maintained. The purpose of TS 4.4.5.4.a.9 is to require the baseline condition of the SG tubes be established prior to placing the SG into service. This surveillance requirement is only applicable for initial plant startup and for any subsequent unit restart following replacement of an SG tube bundle. The requirement that the preservice inspection 01 the tubing be performed only after the field hydrostatic pressure test is considered impractical for replacement of SGs in a plart that has been previcusly inservice.
The preservice inspection serves to provide reasonable assurance that subsequent inservice inspections will provide evidence of structural degradation of the tubes. The proposed TS change does not affect or change this basis, The proposed schedular change does not reduce the effectiveness of the eddy current baseli:w inspection. The shop-performed eddy current examinations will be performed after the required ASME Section III hydrostatic pressure test. Subsequent to installation of the replacement SGs scheduled for 1993 at NA-1, system hydrostatic pressure tests must be performed in accordance with ASt1E Section XI. These test pressures are substantially less than the Section III hydrotest and will not affect the results of the baseline eddy current examinations.
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' t The proposed TS change does not change the intent of the surveillance requirement. The preservice inspection of the tubes of the replacement SGs will still be performed prior to placing the replacement SGs into service.
3.0 EVALUATION The proposed change affects only the schedule for performing the preservice inspection of tubing in the replacement SGs by removing the restriction that the preservice inspection be performed only after the field hydrostatic pressure test. The proposed change is in compliance with the requirements of Regulatory Guide 1.83, Revision 1, and Section XI of the ASME Boiler and Pressure Vessel Code. The proposed change continues to ensure that preservice inspection of replacement SG tubes will be performed to establish the baseline condition of SG tubing. Also, the inspection, as required, will still be performed prior to the resumption of service following the SG replacement and thus ensure that subsequent inservice inspections will provide evidence of structural degradation of SG tubes.
In addition, the proposed schedular change does not reduce the effectiveness of the eddy current baseline inspection. The shop-performed eddy current examinations will be performed after the required ASME Section 111 hydrostatic pressure test. This hydrotest will be conducted at a test pressure of 1.25 times the design pressure.
Subsequent to installation of the SG replace-ment component, system hydrostatic pressure tests must be performed in accordance with ASME Section XI. These test pressures are substantially less than the Section III hydrotest and will not affect the results of the baseline eddy current examinations.
Finally, the proposed change, as discussed above, has been previously approved by the PRC for other operating facilities. Therefore, based o, all of the above, the staff finds the proposed change to be acceptable.
4.0 STATE CONSULTATION
in accordance with the Commission's regulations, the Virginia State official was notified of the proposed issuance of the amendments. The State official had no comment.
5.0 ENVIRONMENTAL CONSIDERATION
These amendments change a surveillance requirement. The NRC staff has determined that the amendments involve no significant increase in the amounts, and no significant change in the types, of any effluent: that may be released affsite, and that there is no significant increase in individual or cumulative occupational radiation exposure. The Commission has previously issued a proposed finding that the amendments involve no significant hazards consideration and there has been no public comment on such finding (56 FR 55950). Accordingly, these amendments r, met the eligibility criteric for categorical exclusion set forth in 10 CFR 51.?2(c)(9). Pursuant to 10 CFR 51.22(b) no environmental impact statement or environmental assessment need be prepared in connection with the issuance of these amendments.
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< t' t 6.0 CONCLUSTON The Commission has concluded, based on the considerations discussed above, that:
(1) there is reasonable assurance that the health and safet not be endangered by operation in the proposed manner, (2) y of the public will such activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendments will not be inimical to the common defense and security or to the health and safety of the public.
Principal Contributor:
L. Engle Date: December 4, 1991