ML20207E763
| ML20207E763 | |
| Person / Time | |
|---|---|
| Site: | Hatch  |
| Issue date: | 06/03/1999 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML20207E760 | List: |
| References | |
| NUDOCS 9906070136 | |
| Download: ML20207E763 (8) | |
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p reau y3 % UNITED STATES
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NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 2005Mc01
. . . . . do SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION THIRD 10-YEAR INTERVAL INSERVICE INSPECTION PROGRAM PLAN REQUESTS FOR RELIEF NOS. RR-4. REV. 2 AND RR-6. REV 2 EDWIN 1. HATCH NUCLEAR PLANT. UNITS 1 AND 2 DOCKET NOS. 50-321 AND 50-366
1.0 INTRODUCTION
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 and applicable addenda as required by Title 10 of the Code of Federal Reaulations (10 CFR) Section 50.55a(g), except where specific written relief has been granted by the Commission pursuant to 10 CFR 50.55a(6)(g)(i). Section 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 attematives would provide an acceptable level of quality and safety or l (ii) compliance with the specified requirements would result in hardship or unusual difficulty j without a compensating increase in the level of quality and safety.
I Pursuant to 10 CFR 50.55a(g)(4), ASME Code Class 1,2, and 3 components (including I supports) shall meet the requirements, except the design and access provisions and the preservice examination requirements, set forth in the ASME Code,Section XI, " Rules for l 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 10-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 50.55a(b) 12 months prior to the start of the 120-month interval, subject to the limitations and modifications listed therein. The Code of record for the Edwin 1. Hatch Nuclear Plant, Units 1 and 2 (Hatch), third 10-year interval is the 1989 Edition of Section XI of the ASME B&PV.
2.0 EVALUATION
.By letter dated June 8,1998, Southern Nuclear Operating Company (licensee) proposed changes to the Third 10-Year Interval inservice inspection Program Plan Requests for Relief (RR) Nos. RR-4 and RR-6 for Hatch, Units 1 and 2.
Enclosure 1
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l The Idaho National Engineering and Environmental Laboratory (INEEL), has evaluated the information provided by the licensee's June 8,1998, letter. Based on the results of the staff's
- review, the staff adopts the contractor's conclusions and recommendations presented in the Technical Evaluation Report (TER) attached.
The information provided by the licensee in support of its attemative to the Code requirements has been evaluated and the basis for disposition is documented below.
~ Reauest for Relief No. RR-4l Rev 2: . ASME Code,Section XI, Examination Categories B-H and B-K-1, items 88.10, B10.10, and B10.20 require a volumetric or surface examination of
- integrally welded attachments as defined by Figures IWB-2500-13, -14, or-15, as applicable.
. Examination Category C-C, items C3.10 and C3.20 require surface examination as defined by Figure IWC-2500-5. Examination Category D-A, D-B, and D-C, items D1.20 through D1.60, D2.20 through D2.60, and D3.20 through D3.60 require VT-3 visual examination as defined by Figure IWD-2500-1.
Pursuant to 10 CFR 50.55a(a)(3)(i), the licensee proposed to use Code Case N 509 for the selection and examination of Class 1,2, and 3 integrally welded attachments with an additional alternative that the licensee will ensure that the sample will be a minimum of 10 percent of the IWB/lWC/ LWD items.
The licensee incorporated Examination Category B-H, integral attachments for vessels, which
, was not included in Revision 1. The licensee has proposed, as an altemative to the Code L
requirements, to apply the requirements of Code Case N-509, "Altemative Rules for the Selection and Examination of Class 1,2, and 3 Integrally Welded Attachments," for the examination of integrally-welded attachments on Class 1,2, and 3 components.
l The Code Case is being supplemented with a minimum examination sample of 10 percent of all H . integral attachments to non-exempt Class 1,2, and 3 piping, pumps, and valves while complying with the Code Case for attachments to Class 1,2, and 3 vessels.
The use of Code Case N-509 was authorized for the Hatch plant in an NRC Safety Evaluation
- i dated June _16,' 1997, without the Examination Category B-H integral attachments for vessels.
l Code Case N-509 is intended to include Category B-H attachments and has been authorized at other plants by the NRC with the 10 percent examination sample commitment for Class 1,2,' and 3 piping, pumps and valves. Additionally, authorization of this proposed attemative has included
' the aforementioned understanding that Class 1,2, and 3 vessels are to be examined in accordance with the Code Case. Therefore, the licensee's proposed attemative, provides an acceptable level of quality and safety and remains authorized pursuant to 10 CFR 50.55a(a)(3)(i).j The use of the Code Case N-509 is authorized for the current interval.
Recuest for Relief No. RR-6. Revision 2: ASME Code,Section XI, Examination Category B-F, item B5.20 requires a 100 percent surface examination of Class 1 safe-end welds in piping less ,
than 4 inches nominal pipe size as defined in Figure IWB-2500-8.
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Pursuant to 10 CFR 50.55a(g)(5)(iii), the licensee had previously requested relief from the Code-required surface examination on Class 1 nozzle-to-safe end butt welds. The staff granted the relief in its letter dated June 16,1997.
J In Revision 2 of this request for relief the licensee removed one of the previously granted nozzle-to-safe-end welds (N10) from the list of welds receiving a VT-2 visual in lieu of the Code-required surface examination. The licensee has determined that weld N10 is accessible and that the code-required surface examination can be performed. RR-6 is unchanged for the other welds. Since Revision 2 to RR-6 represents an increase in the inspection scope, the staff finds ;
it acceptable.
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3.0 CONCLUSION
1 Revision 2 to RR-6 deleted weld N10 because the weld is accessible and the Code-required I surface examination can be performed. This represents an increase in the scope of inspection l and is, therefore, acceptable.
The staff concludes that the licensee's proposed altemative to use Code Case N-509 contained in RR-4 provides an acceptable level of quality and safety. Therefore, the proposed alternative remains authorized pursuant to 10 CFR 50.55a(a)(3)(i) for the current interval or until such time as the Code Case N-509 is published in a future revision of RG 1.147. At that time, if the licensee intends to continue to implement Code Case N-509, the licensee should follow all l provisions in this Code Case, with limitations issued in RG 1.147, if any.
Attachment:
Technical Letter Report Principal Contributor T. McLellan 1
Date: June 3,1999 l
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TECHNICAL LETTER REPORT ;
ON THIRD 10-YEAR INTERVAL INSERVICE INSPECTION !
REQUESTS FOR RELIEF RR-4. REV. 2. AND RR-6. REV. 2 FOR ;
SOUTHERN NUCLEAR OPERATING COMPANY EDWIN 1. HATCH NUCLEAR PLANT. UNITS 1 AND 2 DOCKET NUMBERS: 50-321 AND 50-366 I
- 1. INTRODUCTION By letter dated June 8,1998, the licensee, Southern Nuclear Operating Company, submitted revisions to the Hatch Plant Third 10-Year Inservice Inspection Program. This report only addresses Requests for Relief RR-4, Rev.1, and RR-6, Rev.1, seeking relief from the requirements of the ASME Code,Section XI, for the Edwin I. Hatch Nuclear Plant, Units 1 and 2 for the third 10-year inservice inspection (ISI) interval. The Idaho National Engineering and Environmental Laboratory (INEEL) staff's evaluation of the subject requests for relief are in the following section.
- 2. EVALUATION i
The information provided by Southern Nuclear Operating Company in support of the requests for relief from Code requirements has been evaluated and the bases for i disposition are documented below. The Code of record for the Edwin 1. Hatch Nuclear i Plant, Units 1 and 2, third 10-year ISI interval, which began January 1,1996, is the 1989 Edition of Section XI of the ASME Boiler and Pressure Vessel Code.
A. Reauest for Relief No. RR-4. Rev. 2. Authorization to use Code Case N-509 for Code Class 1. 2. and 3 Intearally Welded Attachments Code Reauirement: Examination Categories B-H and B-K-1, items B8.10, B10.10, and j B10.20 require a volumetric or surface examination of integrally-welded attachments as defined by Figures IWB-2500-13, -14, or -15, as applicable. Examination Category C-C, items C3.10, and C3.20 require sudace examination as defined by Figure IWC-2500-5.
ATTACHMENT LL
' Examination Category D A, D-8, and D-C, items D1.20 through D1.60, D2.20 through D2.60, and D3.20 through D3.60 require VT-3 visual examination as defined by Figure IWD-2500-1. I
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Licensee's Prooosed Alternative: In accordance with 10 CFR 50.55a(a)(3)(i), the licensee. proposed to use Code Case N-509 for the selection and examination of Class 1, ;
, 2, and 3 integrally welded attachments. The licensee stated:
" Southern Nuclear Operating Company proposes that, in lieu of the Code-required .
volumetric, surface, or visual examination on those Integrally Welded Attachments required by Table IWB-2500-1, IWC-2500-1, or IWD-2500-1 in the 1989 Edition, a
- surface examination be performed on those Integrally Welded Attachments as -
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noted in the Code Case [N-509], Table 2500-1, Examination Category B-K, Integral L Attachments for Class 1 Vessels, Piping, Pumps, and Valves; Examination Category C-C, Integral Attachments for Class 2 Vessels, Piping, Pumps, and Valves; and a visual examination for Examination Category D-A, integral !
Attachments for Class 3 Vessels, Piping, Pumps, and Valves. SNC will ensure that the sample will be a minimum of 10% of the IWB/lWC/ LWD items."
Licensee's Basis'for Proposed Alternative (as stated):
" Code Case N 509 provides an alternative sampling which will retain an acceptable level of quality and safety for Class 1,2, and 3 Integrally Welded Attachments.
- Since approval was granted by ASME, the altemative requirements should be I technically acceptable for determining flaws and authorized pursuant to - I 10CFR50.55a(a)(3)(i) provided a minimum of 10% of the total number of integral
- attachments in all Class 1,2, and 3 systems are examined. By implementing the a
~altemative examinations, cost savings, personnel radiation dose, and outage time can be realized by Southern Nuclear Operating Company at Plant Hatch."
Evaluation:' Revision 2 of this request for relief incorporated Examination Category B-H, !
- Integral Attachments For. Vessels, which was not included in Revision 1.. The licensee has proposed, as an alternative to the Code requirements,-to apply the requirements of ;
Code Case N-509, Attemative Rules for the Selection and Examination of Class 1,2, and 3 /ntegrally Welded Attachments for the examination of integrally-welded attachments on
. Class 1,2, and 3 components.-
in a telephone conference call on February 26,1999, the licensee clarified that the Code
- Case is being supplemented with a minimum examination sample of 10% of all integral attachments to non-exempt Class 1,2, and 3 piping, pumps, and valves while complying 1 with the Code Case for attachments to Class 1,2, and 3 vessels.
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t 3-I The use of. Code Case N-509 was authorized for Plant Hatch in NRC SER dated June 16, 1997, without the Examination Category B-H integral attachments for vessels. Code Case ' 509 is intended to include Category B-H attachments and has been authorized at l other plants by the NRC with the 10% examination sample commitment f ar 9l ass 1,2, l and 3 piping, pumps, and valves. Additionally, authorization of this proposed alternative j
! has included the aforementioned understanding that Class 1,2, and 3 vessels are to be '
l examined in accordance with the Code Case. Therefore, the proposed alternative, with the clarification provided in the February 26,1999 conference call, will provide an l acceptable level of quality and safety and should remain authorized pursuant to l 1 10 CFR 50.55a(a)(3)(i). The use of the Code Case should be authorized for the current i interval or until such time as the Code Case is published in a future revision of Regulatory I
Guide 1.147. At that time, if the licensee intends to continue to implemen' this Code Case, the licensee should follow all provisions in Code Case N-509, who limitations issued in Regulatory Guide 1.147, if any, i
l B. Reauest for Relief No. RR-6. Revision 2. Excmination Cateaorv B-F. Item B5.20. J Examination of Reactor Pressure Vessel Nozzle-to-Safe End Butt Welds i
Code Reauirement: Examination Category B-F, item B5.20 requires a 100% surface examination of Class 1 safe-end welds in piping less than 4-inch nominal pipe size as defined in Figure IWB-2500-8.
Licensee's Code Relief Reauest: In accordance with 10 CFR 50.55a(g)(5)(iii), the I licensee requested relief from the Code-requireo arface examination on Class 1 nozzle-to-safe end butt welds.
Unit 1 Unit 2 N15 2N10 N16A 2N15 N168 2N16A 2N16B Licensee'sjasis for Reauesting Relief (as stated):
"These instrument nozzles (N16A/B,2N10,2N16A/B) have very limited access due to the design of the concrete shield. Each nozzle has small doors that can be opened allowing 12 to 18 inches of access. However, due to the distance the RPV
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l wall is recessed from the outside of the shield wall (e.g. insulation thickness, air gap, and shield thickness), the walds cannot be physically reached with enough room to perform the surface exantination.
"The N15 and 2N15 welds are the Bottom Head Drain Nozzles. These welds are I
located in the center of the Bottom head and are not accessible due to the Control Rod Drive Housings (see attached drawings)'.
"VT-2 examination in conjunction with the Class 1 system leakage / hydrostatic test each refueling outage will provide adequate assurance that any flaw (s) that might have propagated through the subject welds are identified and repaired prior to ,
returning the plant to power operation.
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"In addition, other RPV instrument Nozzles which have adequate access (N10, N11NB, N12NB,2N11NB,2N12NB) will receive a Code required surface examination and a supplemental volumetric examination. Therefore, a 60% sample will receive in excess of Code Required surface exams. ;
"The visual examination of the subject nozzles as well u the Code surface exam and supplemental volumetric examination of similar nozzles with the same Code category, will provide reasonable assurance that unallowable inservice flaws have not developed in the subject welds or that they will be detected and repaired prior to return of the reactor vessel to service. Thus an acceptable level of quality and safety will have been achieved and public health and safety will not be endangered by allowing the proposed alternative examination in lieu of Code requirement. SNC therefore requests that the proposed alternative be authorized pursuant to 10 CFR l 50.55a(a)(3)(i)." i Licensee's Proposed Altemative Examination (as stated): !
" Southern Nuclear Operating Company p oposes that, in lieu of the Code-required sunace examination, the following reactor vessel nozzle-to-safe-end butt welds will receive a direct VT-2 examination: N15, N16NB, 2N10, 2N15, "N16NB."
Evaluation: Pevision 2 of this request for relief removed one of the previously granted nozzle-to-safe end welds (N10) from the list of t' elds receiving a VT-2 visualin lieu of the Code-required surface examination. This change reflects a decrease in scope for this ru.af therefore, does not affect the previous evalustion. I The licensee has requested relief from performing the Code-required surface examination of the subject safe-end welds. Based on a review of the sketches provided,
'Not included with this evaluation .
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l it has been determined that the Code-required surface examinations of the subject areas l are impractical due to inaccessibility. The N15 and 2N15 nozzle safe-ends are located I
within the control rod drive housing assembly in the center of the bottom head, and the l
N16NB,2N16NB, and 2N10 nozzle safe-ends are located out of reach inside the bioshield. To provide access for a surface examination, design modifications would be required. imposition of this requirement would cause a considerable blirden on the licensee.
1 The licensee proposes to perform direct VT-2 visual examinations of the subject examination areas. In addition, the licensee will perform a volumetric examination in conjunction with the Code-required surface examination on the N10, N11NB, N12NB, 2N11NB, and 2N12NB nozzle safe-ends. These nozzles / safe-ends are similar in design i
to the subject safe-ends. Consequently, the licensee is performing examinations in i excess of Code requirements for more than 50% of the item B5.20 nozzle-to-safe end butt welds. Based on the licensee's proposed alternative, it is reasonable to conclude that generic degradation, if present, will be detected. As a result, reasonable assurance of continued structural integrity will be provided. Therefore, it is recommended that relief remain granted pursuant to 10 CFR 50.55a(g)(6)(i). !
- 3. CONCLUSION The INEEL staff evaluated the licensee's submittal and concluded that certain inservice examinations cannot be performed to the extent required by the Code at the Edwin 1. :
Hatch Nuclear Plant, Units 1 and 2. For Request for Relief RR-6, the proposed testing provides reasonable assurance of the structuralintegrity of the subject nozzle-to-safe end welds and it is recommended that relief remain granted pursuant to 10 CFR 50.55a(g)(6)(i). For Request for Relief RR-4, Code Case N-509 provides an acceptable level of quality and safety, therefore, the proposed alternative should remain authorized pursuant to 10 CFR 50.55a(a)(3)(i).
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