ML20196H245
| ML20196H245 | |
| Person / Time | |
|---|---|
| Site: | Pilgrim |
| Issue date: | 06/29/1999 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML20196H241 | List: |
| References | |
| NUDOCS 9907060169 | |
| Download: ML20196H245 (8) | |
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g j NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 2055MX)01 ]1
- * * * * ,o l SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION l
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THIRD 10-YEAR INTEREL INSERVICE INSPECTION l
, REQUEST FOR RELIEF FOR BOSTON EDISON COMPANY PILGRIM NUCLEAR POWER STATION DOCKET NO. 50-293 1'.0 INTRODUCTION L
Inservice inspection of the Americcn Society of Mechanical Engineers (ASME) Code Class 1,2,
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and 3 components shall be performed in accordance with Section XI of the ASME Boiler and i
Pressure Vessel (B&PV) Code (the Code) and applicable addenda as required by Title 10 of the Code of Federal Reaulations (10 CFR) Part 50.55a(g), except where specific written relief has been granted by the Commission pursuant to 10 CFR 50.55a(g)(6)(i). Title 10 of the Code )
of Federal Reaulati.o_0 (10 CFR) Part 50.55a(a)(3) states that alternatives to the requirements of i paragraph (g) may be used, when authorized by the Nuclear Regulatory Commission (NRC), if {
(i) the proposed alternatives would provide an acceptable level of quality and safety, or (ii) j compliance with the specified requirements would result in hardship or unusual difficulty without l
) 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 l 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 3 Inservice Inspection of Nuclesr Power Plant Components," to the extent practical within the !
limitations of desi0n, geometry, and materials of construction of the components. The i regulations require that inservice examination of components and system pressure tests conducted during the first 10-year interval and subsequent intervals comply with the a requirements in the lates, edition and addenda of Section XI of the ASME Code incorporated by reference in 10 CFR 50.55a(b) 12 months prior to the start of the 120-month interval, subject to the limitations and modifications listed therein. The applicable edition of Section XI of the ASME Code for the Pilgrim Nuclear Power Station (PNPS) is the 'J9 Edition of Section XI of the ASME B & PV Code.
By letter dated August 20,1998, Boston Edison Company, submitted to the NRC its proposed alternative to the Code requirements in Relief Request PRR-13, Revision 2, for the pressure testing of the containment penetration piping examination specified in Table IWC-2500-1 for ;
9907060169 990629 PDR ADOCK 05000293 P PDR Enclosure 1 L J
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. PNPS during the third 10-year interval. The licensee has proposed the use of Code Case N-522, and its Appendix J Testing, in lieu of Table IWC-2500-1, pressure testing of containment penetration piping. The t,taff has reviewed and evaluated the licensee's proposed alternative and the supporting laformation, pursuant to 10 CFR 50.55a(a)(3)(i) for PNPS.
2.0 ' EVALUATION The staff with technical assistancs from its contractor, the Idaho National Engineering and Environmental Laboratory (INEEL), has evaluated the information provided by the licerisee in support of its request for an altemative to the Code requirements during the third 10-year inservice inspection interval. While INEEL and the staff reached the same conclusion, the staff had a different basis for the denial. The staff's evaluation is provided below.
- Request for Relief PRR-13 (Revision 2): This relief request involves the use of Code Case N-522, Pressure Testing of Containment Penetration Piping, Table IWC-2500-1, Examination Category C-H, All Pressure Retaining Components, item Nos. C7.30 and C7.40
_c - Table IWC-2500-1, Category C-H, requires pressure testing of piping penetrations in
. accordance with IWC-5221 system pressure test and IWC-5222 system hydrostatic test and accompanying VT-2 examination, and IWC-5222 hydrostatic test may be used in place of IWC-5221 systsm pressure test for item C7.30. In accordance with 10 CFR 50.55a(a)(3)(i), the licensee proposed.to use Code Case N-522, Pressure Testing of Containment Penetration Piping, as an alternative to the Code-required examinations.
l The proposed use of Code Case N-522 alone is not sufficient to meet the Code requirements.
The Code case only provides for an alternative method for cond Jcting the pressure test to be performed as part of the code examination. Therefore, use of the Code case, in part, oNy i
' satisfies the pressure testing requirements, and the VT-2 visual examination and acceptance standards for items C7.30 and C7.40 are still required. Conducting Appendix J testing does not by itself provide reasonable assurance that structural integrity will be maintained since an ;
essential part of this inspection activity involvss detection and location of the source of leakage.
l A containment leak rate test, on the other hand, would be acceptable when the leakage is below an acceptable limit, but would not establish that a length of pipe has not developed any leakage.
The licensee has provided no information on leak detectior' ~vi location, type of Appendix J <
Testing (A or B) which will be used, or on associated examination frequencies for PNPS, if Code Case N-522 were to be implemented. In addition, the licensee has not specified how leakage in the piping between containment isolation valves (CIV's) will be identified when pressure testing with air, as water could adversely impact the service life of the CIV's.
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3.0 CONCLUSION
On the basis of'the preceeding evaluation, the NRC staff has determined that the licensee's l
proposed alternative in Relief Request PRR-13, Revision 2, provides insufficient information to ;
determine the adequacy of the scope of implementation of the proposed afternative.
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Consequently, it does not provide reasonable assurance'that structural integrity will be ,
, maintained. .Therefore, request for rellef PRR-13, Revision 2, is denied. I Principal Contributor: G. Hatchett Date: June'29 1999 l
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l TECHNICAL LETTER REPORT ON THIRD 10-YEAR INTERVAL INSERV!CE INSPECTION REQUEST FOR RELIEF PRR-13 REVISION 2 FOR BOSTON EDISON COMPANY PILGRIM NUCLEAR POWER STATION DOCKET NO. 50-293
- 1. INTRODUCTION By letter dated August 20,1998, the licensee, Boston Edison Company, submitted Amendment 98-01 to the Pilgrim Inservice Inspection (ISI) Program. Amendmon! 98-01 included Request for Relief PRR-13, Revision 2, seeking relief from the requirements of the A6tviE Code.Section XI, for the Pilgrim Nuclear Power Station third 10-year inservice inspection (ISI) interval. The Idaho National Engineering and Environmental Laboratory (INEEL) staff's evaluation of the subject request for relief is in the following section.
- 2. EVALUATION The information provided by Boston Edison Company in support of the request for relief from Code requirements has been evaluated and the basis for disposition is documented below. The Code of record for the Pilgrim Nuclear Power Station, third 10-year ISI interval, which began July 1,1995, is the 1989 Edition of Section XI of the ASME Boiler and Pressure Vessel Code.
Reouest for Relief No. PRR-13. Revision 2. Use of Code Case N-522. Pressure Testina of Containment Penetration Pioina Code Reouirement: ASME Section XI, Table IWC-2500-1, Examination Category C-H, requires pressure testing of all Class 2 pressure-retaining components in accordance with IWC-5221 and IWC-5222.
Licensee's Proposed Alternative: Pursuant to 10 CFR 50.55a(a)(3)(i), the licensee proposed to use the attemative requirements contained in Code Case N-522, Pressure Testing of Containment Penetration Piping, for the following portions of piping.
Enclosure 2
2 PENETRATION NUMBER LINE DESCRIPTIONX-32A I NUMBER 1"-DC-45 Rx. Pressure X-46D Boundary L e a k 93tection System Retum l
Line to Drywell 1"-HCB-45 Drywell Level X-219 Line }
4 4"-HCB-45 HPCI Turbine X-2288 Exhaust Vacuum and Hydrogen Reccmbiner Vent 1"-DC-45 Torus X-25 Pressure 4 18"-HM-45 Vent from X-26 Drywell ,
18"-HM-9 Vent to X-205 Drywell 20"-HM-45 Torus Purge X-227 Inlet l
20"-HM-45 Torus Purge X-29E !
Exhaust Vacuum Relief and Direct Torus Vent
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1"-DC-45 PASS Train X-15E
'A' Drywell l Gas Sample I Line 1"-DC-45 PASS Train X-106A-b
'B' Drywell Gas Sample l Line -
1"-DC-45 PASS Train X-50A-d l
'A' Drywell l
Gas Sample l Line
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( 1"-DC-45 PASS Train X-46F
'B' Drywell Gas Sample l Line 1"-DC-45 PASS Train X-22
'A' Drywell Return Line 3"-HCB-31 Instrument Air X-228J 1"-DC-45 PASS Train X-228C
'A' Torus Gas Sample Line 1"-DC-45 PASS Train X-228K
'B' Tcrus Gas Sample Line 1"-DC-45 PASS Train
'B' Torus Return Line The licensee stated:
" Boston Edison proposes the use of Code Case N-522 at Pilgrim Nuclear Power Station with the following modifications as an alternative to the C- ' tion XI Category C-H pressure test requirements for piping and valves at containment penetrations where the balance of piping is outside the scope of Section XI:
9 " Boston Edison shall perform 10 CFR 50 Appendix J leakage tests on the containment penetration piping and valves listed in Table 1 at the peak calculated containment pressure (45 psig) in accordance with Pilgrim Station procedures as an alternative to the Section XI 40 month system pressure test Code items C7.30 and C7.70 and VT-2 requirement."
9 " Boston Edison shall also perform 10 CFR 50 Appendix J leakage tests on the containment penetration piping and valves listed in Table 1 at the peak calculated containment pressure (45 psig) in accordance with Pilgrim Station '
procedures. Test procedures will permit the detection and location of through-wall leakage by VT-2 certified examiners on accessible piping as an ,
alternative to the Section XI ten year hydrostatic test, Code items C7.40 and
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C7.80 requirement. Piping segments located in areas where direct VT-2 i examination is considered impractical are listed in Table 2. These segments I shall be tested using Appendix J test procedures but will not be VT-2 visually examined." l Licensee's Basis for Proposed AlternatLve (as stated):
"This request for relief is based on two issues: 1) Use of Code Case N-522 (with alternate provisions from Draft Regulatory Guide DG-1050) and 2) Inspection limitations based on impracticality or ALARA.
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"1) Use of Code Case N-522 (with alternate orovisions)
" Code Case N-522 (with alternate provisions from Draft Regulatory Guide DG-1050) allows the use of air instead of water as the test medium and use of the Appendix J peak calculated containment pressure (45 psig at Pilgrim NPS)in lieu of the test pressure required for the 10 year code hydrostatic test. The VT-2 examination requirement for the code 40 month system pressure test is also eliminated.
" Boston Edison believes that the use of Appendix J test methods in accordance with Code Case N-522 for Class 2 piping and valves at containment penetrations is an acceptable alternative to Section XI pressure testing since the piping and valves listed in Table 1 are categorized as Class 2 due to their containment pressure boundary function. The balance of the systems are e
outside the scope of Section XI. Appendix J test methods and criteria are the accepted means for the verification of leak-tight integrity of containment pressure boundary components and therefore provide an acceptable level of quality cnd safety. Use of code hydrostatic test methods with VT-2 examination is not a practical option for the subject piping and valves since the containment isolation valves (CIV) are designed for use in air systems. Pressure testing with water could adverset/ impact the service life of the C!V's.
"2) Insoection limitatens based on imoracticality or ALARA M are located in areat where access is difficult causing direct VT-2 examination to be imptactical. Boston Edison believes this constitutes a hardship with no compensating increase in tne level of quality and safety. A significant staging and, in some cases, insulation removal effort would be required for the piping segments listed in Table 2 below to be bubble tested (or tested using equivalent methods) with VT 2 examiners (using Code Case N-522 during Appendix J testing) to detect the source of through-wallleakages. The original design did not anticipate direct visual examination. system pressures and temperatures for these piping segments and valves during normet plant operations are typically low (1.5 psig & loo degrees F) with the most severe service conditions imposed by periodic, Appendix J testing at the peak accident test pressure of 45 psig.
There is no known degradation mechanicrh or normal operving condition that would adversely impact the structuralintegrity of this piping. Direct VT-2 examination would not significantly increase the level of quality and safety since the method can only detect through-wal' defects. A flaw that has not propagated entirely through-wall could conceivably have a negative impact on structuralintegrity and still not be detected by a VT-2 exam. Therefore, a direct VT-2 examination at nominal operating pressures does not constitute a verification of piping structural integrity, but only of leak tightness. Appendix J testing of this piping provides an adequate level of quality and safety since it is the accepted means to verify the leak-tight integrity of the primary containment system." #
Evaluation: The Code requires a VT-2 visual examination during system pressure testing for all Class 2 pressure-retaining piping, including those segments that penetrate primary containment. As an attemative, the licensee proposed to implement the requirements of Code Case N-522, Pressure Testing of Containment Penetration Piping. Code Case N-522 specifies that 10 CFR 50, Appendix J testing may be used as an alternative to Section XI pressure tests for certain containment penetration piping.
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Apperid'ix J contains two options for examination requirements.. Option A, Prescrhive L ' Requirements, requires that three Type A tests be performed at approximately equalintervals
> l during the 10 pear ISI interval, with the third test being done while shutdown for the 10-year plant ISI.' Option A also requires Type B and C tests during each refueling outage, but in no case at intervals greater than 2 years. ' This is more frequent than the periodic pressore tests required by ASME Section XI. Appendix J, Option B, Performance Based Requirements, allows a licensee to perform Type A, B, and C tests at frequencies related to the safety significance and historical performance of the system's isolation capabilities. This could, in effect, allow only one test to be performed during the 10-year ISI interval. The staff's position, as stated in Regulatory Guide 1,163, Performance-Based Containment Leak-Test Program, is that the licensee is to ,
establish test intervals of no greater than 60 months for Type C tests because of uncertainties in historical Type C component performance dtla (particularly unquantified leakage rates for test failures, repetitive / common mode failures, and aging effects). While this five-year limit results in an increased time between' testing over that required by Section XI (forty months), it is believed that Appendix J tests are more appropriate and provide reasonable assurance of the continued operability of containment penetrations.
The licensee has provided no information on which option (A or B) will be used or on associated examination frequencies for Pilgrim Nuclear Power Station. Thus, it is unclear whether the
' licensee's proposed test frequencies will exceed the 60 month interval for a Type C test specified in Regulatory Guide 1.163. Therefore, it is recommended that the proposed alternative not be authorized.
- 3. CONCLUSION The INEEL staff evaluated Request for Relief PRR-13, Rev. 2, and concluded that the licensee has not supplied an alternative examination providing'an acceptable level of quality and safety.
~ Therefore, it is recommended that Request for Relief PRR-13, Rev. 2, not be authorized.
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