ML20205S039
| ML20205S039 | |
| Person / Time | |
|---|---|
| Site: | North Anna  |
| Issue date: | 04/21/1999 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML20205S038 | List: |
| References | |
| NUDOCS 9904260064 | |
| Download: ML20205S039 (16) | |
Text
Nog.
4 e*
4
- UNITED STATES p
,g NUCLEAR REGULATORY COMMISSION o
WASHINGTON, D.C. 20565-0001
%...../
SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION EVALUATION OF RELIEF REQUESTS
~
IMPLEMENTATION OF SUBSECTIONS IWE AND IWL OF ASME SECTION XI FOR CONTAINMENT INSPECTION NORTH ANNA POWER STATION. UNITS 1 AND 2 DOCKET NOS. 50-338 AND 50-339
1.0 INTRODUCTION
By letter dated August 4,1998 (Ref.1), the licensee, Virginia Electric & Power Company, submitted relief request Nos. RR-lWE2, RR-lWE3 (Unit 1 only), RR-lWE4, RR-lWE5, RR-lWE6, and RR-lWL2, seeking relief from some of the ASME Code,Section XI, Subsections IWE and IWL requirements for North Anna Power Station, Units 1 and 2. RR-lWE3 was subsequently withdrawn by the licensee's letter dated April 5,1999. These relief requests have been submitted for the inspections to be performed during the second 10-year inservice inspection (ISI) interval. However, the licensee has elected to begin a separate interval for containment
' inspections.
Pursuant to 10 CFR 50.55a(b) and (g), inservice inspection of containment must meet the requirements of the 1992 Edition,1992 Addenda of Section XI, Subsections IWE and IWL.
Pursuant to 10 CFR 50.55a(g)(6)(ii)(B), the first period containment examinations must be completed by September 9,2001. Alternatives to the requirements of 10 CFR 50.55a(g) may be authorized under 10 CFR 50.55a(a)(3), if (i) the proposed alternative provides an acceptable level of quality and safety, or (ii) compliance with the specific requirement of the Code would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety.
9 The staff, with the assistance of the Idaho National Engineering and Environmental Laboratory
-(INEEL) evaluated the information provided by the licensee. Based on its review, the staff adopts INEEL's conclusions and recommendations as provided in its Technical Letter Report (Attachment), unless otherwise stated in the specific staff evaluation, i.e. RR-lWL2.
2.0 EVALUATION
- . 2.'1 Reauest for Relief RR-lWE2 (Units 1 and 2)
Code Reauirement: ' Examination Category E-D, items E5.10 and E5.20 require visual examination, VT-3, on 100% of each item. Seals and gaskets shall be examined for wear, damage, erosion, tear, surface cracks, or other defects that may violate the leaktight integrity.
Defective items shall be repaired or replaced.
)
l Enclosure P-
-PDR 1
j
=
_ Licensee's Proposed Alternative: In accordance with 10 CFR 50.55a(a)(3)(ii), the licensee proposed to perform a leaktight integrity examination in accordance with Appendix J in lieu of
(
i the required VT-3 examinationc. The licensee stated:
The leak-tightness of seals and gaskets will be tested in accordance with 10 CFR 50, j
Appendix J. The 10 CFR 50 Appendix J Type B testing is performed at least once each inspection interval.
Staff Evaluation: Compliance with the Code requires disassembly of the subject components to gain access for the VT-3 visual examination of the gaskets and seals. The 1993 Addenda to j
Section XI has recognized that disassembly of joints for the sole purpose of pedormance of the visual examination is unwarranted. Requiring the licensee to disassemble components for the
)
sole purpose of inspecting seals and gaskets would place a significant hardship on the licensee without a compensating increase in quality and safety. The staff agrees with the INEEL staff that reasonable assurance of the functionality and integrity of the containment penetration seals and gaskets will be provided during Type B testing as required by 10 CFR Part 50, Appendix J.
l Therefore, the proposed alternative is authorized pursuant to 10 CFR 50.55a(a)(3)(ii).
]
2.2 Reauest for Relief RR-lWE4 (Units 1 and 2)
Code Reauirement: Paragraph IWE-2420(b) requires that when component examination results require evaluation of flaws, evaluation of areas of degradation, or repairs in accordance with IWE-3000 and the component is found to be acceptable for continued service, the areas containing such flaws, degradation, or repairs shall be reexamined during the next inspection j
period. The reexaminations shall be performed in accordance with Examination Category E-C and at the schedule specified in the inspection requirements of IWE-2411 or IWE-2412.
Paragraph IWE-2420(c) requires that when the reexaminations required by Paragraph IWE-2420(b) reveal that the flaws, areas of degradation, or repairs remain essentially unchanged for three consecutive inspection periods, the areas containing such flaws, degradation, or repairs no longer require augmented examination in accordance with Table IWE-2500-1, Examination Category E-C.
}
Licensee's Proposed Alternative: In accordance with 10 CFR 50.55a(a)(3)(ii), the licensee proposed an alternative to the Code successive examination requirements for repairs. The licensee stated:
Successive examinations in accordance with Paragraphs IWE-2420(b) and IWE-2420(c) are not required for repairs made in accordance with Article IWA-4000.
The licensee contends that performance of successive examination for repairs made in accordance with Article IWA-4000 is a burden without a compensating increase in the level of quality and safety.
Staff Evaluation: Articles IWB-2420(b), IWC-2420(b), and IWD-2420(b) of Section XI of the ASME Code (related to Class 1, Class 2, and Class 3 components) do not require the l
l L
4 successive inspection of repairs as required in lWE-2420(b). Considering that the failure mechanism is identified and corrected as required by the Code and the repair receives preservice examinations, performance of the successive examinations presents an unnecessary burden on the licensee without a compensating increase in safety, Therefore, the relief as proposed by the licensee is authorized pursuant to 10 CFR 50.55a(a)(3)(ii) for repaired components only.
2.3 Reauest for Relief RR-lWE5 (Units 1 and 2)
Code Reauirement: Examination Category E-G, item E8.20, requires a bolt torque or tension j
test of bolted connections each inspection interval.
1 Licensee's Proposed Alternative: in accordance with 10 CFR 50.55a(a)(3), the licensee i
proposed an alternative to the Code-required bolt torque or tension test. The licensee stated:
The following examinations and tests required by Subsection IWE ensure the structural integrity and the leak-tightness of Class MC presssre retaining bolting, and therefore, no additional alternative examinations are proposed:
1 I
(1)
Exposed surfaces of bolted connectione shall be visually examined in accordance with the requirements of Table IWE-2500-1, Examination Category E-G, Pressure Retaining Bolting, item No. E8.10, and (2)
Bolted connections shall meet the pressure test requirements of Table IWE-2500-1, Examination Category E-P, All Pressure Retaining Components, item E9.40.
Staff Evaluation: Containment penetration integrity is to be verified by performance of the Code-required visual examination of the bolting in conjunction with the Type B test. The staff agrees with the opinion of the INEEL staff that bolt torque or tension testing does not provide assurance that a pressure seat exists at a containment penetration and that the Type B test is adequate for assuring that the bolted connection is performing its designated function. The licensee's proposed alternative provides an acceptable level of quality and safety since Type B testing provides the final verification of an acceptable pressure seal at the containment penetration while the integrity of the bolting itself is verified by the Code-required VT-1 visual examination.
Based on the assurances provided by the existing Code-required VT-1 visual examinations and the leak-rate determinations provided by Appendix J, Type B tests, the licensee's proposed alternative is authorized pursuant to 10 CFR 50.55a(a)(3)(i).
2.4 Reauest for Relief RR-lWE6 (Units 1 and 2)
Code Reauirement: IWE-2500(c)(3) requires that when ultrasonic thickness measurements are performed one-foot square grids shall be used. The number and location of the grids shall be determined by the owner. iWE-2500(c)(4) requires the minimum wall thickness within each grid to be determined.
. Licensee's Prooosed Alternative: In accordance with 10 CFR 50.55a(a)(3)(ii), the licensee proposed an alternative to using one-foot square grids for augmented examination areas and the requirement to determine the minimum wall thickness within each grid. The licensee stated:
Table RR-lWE6 will be used to determine examination requirements for ultrasonic thickness measurements of areas requiring augmented examination.
i Staff Evaluation: Table RR-lWE6, attached to the relief request, provides an alternative to the one-foot square grid area required by IWE-2500(c)(3). Table RR-lWE6 requires examination at the grid line intersections. The distance between grid line intersections may not exceed 12 inches and may be as small as 2 incnes.
For a sample area of 50 square feet, Table RR-lWE6 requires a minimum of 100 locations be monitored. For a sample area of 50 square feet, IWE-2500(c)(3) would require only 50 locations be monitored. In this instance, using Table RR-lWE6 would require monitoring more locations than required by IWE-2500(c)(3).
For sample areas greater than 100 square feet, Table RR-lWE6 requires that sufficient points be monitored to ensure at least a 95% confidence level that the thickness of the base metalis reduced by no more than 10% of the nominal plate thickness at 95% of the grid line intersections. Table RR-lWE6 also requires additional examinations when any measurements reveal wall thickness is reduced by more than 10% of the nominal plate thickness.
This alternative is essentially equivalent to Code Case N-605, Altemative to the Requirements of IWE-2500(c) for Augmented Examination of Surface Areas (under staff review). Also, the staff has endorsed the sampling criteria used by the licensee in Table RR-lWE6 in similar conditions.
The time and number of the examinations to be performed would relate directly to the additional potential radiation that plant personnel would be exposed to by performance of 100%
examination coverage. Subjecting the licensee to this requirement would result in a significant burden without a compensating increase in quality and safety. The staff thus agrees with the INEEL staff that the proposed alternative provides a sampling methodology similar to that of other Code requirements and other erosion / corrosion monitoring programs utilized throughout the industry. Therefore, the staff concludes that the licensee's proposed alternative will provide reasonable assurance of structuralintegrity and is authorized pursuant to 10 CFR 50.55a(a)(3)(ii).
2.5 Reauest for Relief RR-lWL2 (Units 1 and 2)
Code Reauirement: IWA-2210 specifies the requirements associated with visual examinations, including illumination requirements and maximum examination distances for direct and remote VT-1, VT-2, and VT-3 examinations. Specifically, the Code requires minimum illumination of 50 Footcandles (Fc), maximum direct examination distances of 4 feet, and maximum procedure demonstration character height of 0.105 inch to perform a direct VT-3 visual examination.
Licensee's Proposed Alternative: In accordance with 10 CFR 60.55a(a)(3)(ii), the licensee proposed an alternative to the requirements of IWA-2210 of the 1992 Addenda. As an
l j
5-alternative, the licensee proposed to use the requirements of the 1989 Edition of Section XI for VT-3 visual examinations. The licensee stated:
VT-3C visual examinations will be performed under distance and illumination requirements necessary to detect the conditions or indications for which the visual examination is performed. The procedure will be demonstrated capable of detecting conditions or indications for which the examination is being performed.
Staff Evaluation: The regulation allows some latitude in the distance and illumination requirements for remote visual examination of IWE components. The staff agrees with the INEEL staff that the information provided in the licensee's proposed alternative is not adequate for evaluating its equivalency with the VT-3C visual examination. However, the staff does not agree with the INEEL staff's recommendation to deny the relief request. Based on the similar acceptance for the IWE components, the staff considers the licensee's commitment, "the procedure will be demonstrated capable of detecting conditions or indications for which the examination is being performed," adequate for granting this relief. The staff authorizes the relief pursuant to 10 CFR 50.55a(a)(3)(ii).
3.0 CONCLUSION
Based on the information provided in the relief requests, the staff concluded that for Request for Relief No IWE5 the licensee's proposed alternative will provide an acceptable level of quality and safety. Therefore, the proposed alternative is authorized for the containment inspections pursuant to 10 CFR 50.55a(a)(3)(i). For Requests for Relief Nos. lWE2, IWE4, IWE6, and IWL2, the staff concluded that compliance with the Code requirements would result in a burden without a compensating increase in the level of quality and safety and that the licensee's proposed alternatives will provide reasonable assurance of quality and safety. Therefore, these proposed alternatives are authorized for the containment inspections pursuant to 10 CFR 50.55a(a)(3)(ii).
Principal Contributor: Hansraj G. Ashar j
Date:
April.21, 1999
n TECHNICAL LETTER REPORT ON SECOND 10-YEAR INTERVAL INSERVICE INSPECTION REQUESTS FOR RELIEF EOB VIRGINIA ELECTRIC AND POWER COMPANY NORTH ANNA POWER STATION, UNITS 1 AND 2 ROCKET NUMBERS: 50-338 AND 339 1.
INTRODUCTION By letter dated August 4,1998, the licensee, Virginia Electric and Power Company, submitted proposed alternatives to the requirements of the ASME Code,Section XI, for the North Anna Power Station, Units 1 and 2, second 10-year inservice inspection (ISI) interval. The Idaho National Engineering and Environmental Laboratory (INEEL) staff's evaluation of the subject proposed alternatives are in the following section.
2.
EVALUATION The information provided by Virginia Electric and Power Company in support of the proposed alternatives to Code requirements have been evaluated and the bases for disposition are documented below. The Code of record for the North Anna Power Station, Units 1 and 2, second 10-year ISI interval, is the 1983 Edition, through summer 1983 Addenda, and the 1986 Edition, respectively, of Section XI of the ASME Boiler and Pressure Vessel Code. The second 10-year interval ended in December 1998 for Unit 1 and is scheduled to end in December 2000 for Unit 2.
As required by 10 CFR50.55a(g)(6)(ii)(8), the examination requirements for the containment are in accordance with Sections IWE and IWL of the 1992 Edition,1992 Addenda of Section XI. The following requests are seeking relief from the requirements of the 1992 Edition with the 1992 Addenda.
2.1 Reauest for Relief RR-lWE2 (Units 1 and 2). Examination Cateaorv E-D. Item E5.10 and E5.20. and E5.20. Seals. Gaskets, and Moisture Barriers Code Reauirement: Examination Category E-D, Items E5.10 and E5.20 require visual examination, VT-3 on 100% of each item. Seals and gaskets, shall be examined for wear, damage, erosion, tear, surface cracks, or other defects that may violate the leak-tight integrity. Defective items shall be repaired or replaced.
Licensee's Proposed Alternative: In accordance with 10 CFR 50.55a(a)(3)(ii), the licensee proposed to perform a leak tight integrity examination in accordance with Appendix J in lieu of the required VT-3 examinations. The licensee stated:
l "The leak-tightness of seals and gaskets will be tested in accordarice with 10 CFR 50, Appendix J. The 10 CFR Appendix J Type B testing is performed at least once each inspection interval."
ATTACHMENT l
r
. Licensee's Basis for Proposed Alternative (as stated):
"The components discussed below contain seals and gaskets.
" Electrical Penetrations:
Electrical penetrations use a header plate attached to a containment penetration l
nozzle flange with redundant 0-rings between the header plate and flange face.
Modules through which electrical conductors pass are installed in the header plete.
One type, manufactured by Amphenol, uses seals and gaskets to assure leak tight integrity. A second type, manufactured by Conax, uses a set of compression fittings.
Replacement modules for the Amphenol penetrations use a combination of O-rings and compression fittinos. Each penetration is pressurized with dry nitrogen to maintain and monitor integrity and to prevent the intrusion of moisture into the penetration. These seals and gaskets cannot be inspected without disassembly of the penetration to gain access to the seals and gaskets.
" Containment Personnel. Eauioment. and Emeraency Escaoe Hatches:
The personnel, equipment, and emergency escape hatches utilize an inner and outer door with gesketed surfaces to ensure a leak tight integrity. These hatches also contain other gaskets and seals such as electrical penetrations and equalizing pressure connections, which require disassembly to gain access to the gaskets and seals.
" Fuel Transfer lu_b_g:
"The fuel transfer tube utilizes a blank flange inside containment with redundant O-rings between the header and flange face".
"Per 10 CFR 50 Appendix J, seals and ga6kets receive a Type B test. As noted in 10 CFR 50, Appendix J, the purpose of Type B tests is to measure leakage of containment or penetrations whose design incorporates resilient seals, gaskets, sealant compounds, and electrical penetrations fitted with flexible metal seal I
assemblies. For those penetrations that are routinely disassembled, a type B test is required upon final assembly and prior to start-up. For those penetrations that are not routinely disassembled, Table IWE-2500-1, Category E-D, Note 1 (1993 Addenda i
and later) states ' Sealed or gasketed connections need not be disassembled solely for the purpose of examination.' Therefore, these seals and gaskets would not be visoally examined.
" Table IWE-2500-1, Category E P, item E9.40, requires performance af an Appendix J Type B tests for seals and gaskets. Since the Type B test will assure the leak tight integrity of primary containment at the same frequency as that of the Code visual
{
exams, the performance of the visual examination is redundant and will not increase the level of cafety or quality.
1
3-
" Relief is requested in accordance with 10 CFR 50.55a(a)(3)(ii). Compliance with the visual examination of sea;s and gaskets is accordance with IWE-250, Table IWE-2500, Category E-D is a hardship without any compensating increase in the level of quality and safety. Visual examination of seals and gaskets will not ensure leak tight integrity, implementing and ASME Section XI Code program to perform these examinations is on unnecessary administrative burden. Testing the 'als and gaskets in accordance with 10 CFR 50, Appendix J is superior to performing a visual examination an provides assurance of the leak-tight integrity of the seals and gaskets. The Appendix J testing frequency is greater than that of ASME Section XI, i
and therefore is more conservative and provides a greater level of safety. Appendix a testing is a superior alternative method of establishing sealintegrity."
Evaluation: The Code requires that seals and gaskets on air locks, hatches, and other devices be VT-3 visually examined once each interval to verify the condition of the gaskets and seals as well as help assure containment leak-tight integrity. The licensee proposed to use the existing 10 CFR 50, Appendix J, Type B testing as a verification of seal and gasket integrity, rather than disassembling the subject components for the sole purpose of examination.
Compliance with the Code requires disassembly of the subject components iu gain access for the VT-3 visual examination of the gaskets and seals. The 1993 Addenda to Section XI has recognized that disassen>.bly of joints, for the sole purpose of performance of the visual examination, is unwarranted. Requiring the licensee to disassemble components for the sole purpose of inspecting seals and gaskets would place a significant hardship on the licensee without a compensating increase in quality and safety. The INEEL staff believes that reasonable assurance of the functionality and integrity of the containment penetration seals and gaskets will be provided during the Type B testing as required by the 10 CFR Part 50, Appendix J, test. Therefore, it is recommended that the proposed alternative be authorized pursuant to 10 CFR 50.55a(a)(3)(ii).
2.2 Reauest for Relief RR-;Wt-3 (Unit 1). IWE-5000, System Pressure Tests Followina RepJr. Modification, or Reolacement of Class MC or Class CC comoonen_Is i
Code Reauirement: Paragraph IWE-5240 specifies the requirements of IWA-5240 for visual examinations following repair, replacement, or modification.
Licensee's Proposed Alternative: In accordance with 10 CFR 50.55a(a)(3)(i), the licensee proposed an alternative to the Code-required VT-2 visual examination of repair and replacements. The licensee stated:
" Testing and examination shall be conducted in accordance with 10 CFR 50, Appendix J as applicable. A preservice visual examination will be performed on the repair / rep!acement."
. - Licensee's Basis for Proposed Alternative (as stated):
" Repair / replacements are performed in accordance with the Virginia Power Repair / Replacement Program which specifies the repair methods and nondestructive examinations necessary to ensure the original quality and constructions requirements of the containment vessel are met.
"ASME Section XI, Paragraph IWE-5210 states that except as noted within Paragraph IWE-5240, the requirements of Article IWA-5000 are not applicable to Class MC or Class CC components. Paragraph IWE-5240 states that the requirements of Paragraph IWA-5240 for visual examinations are applicable. Paragraph IWA-5240 identifies a 'VT-2' visual examination. VT-2 examinations are conducted to detect evidence of leakage from pressure retaining components, with or without leakage collection systems, as required during the conduct of a system pressure test. In addition, personnel performing VT-2 examinations are required to be qualified in accordance with Subarticle IWA-2300 of ASME Section XI.
" Table IWE-2500-1, Fv ination Category E-P, identifies the examination method of 10CFR50, Appendik.
.owing each repair, modification, or replacement and does not specifically ident., a VT-2 visual examination.10CFR50. Appendix J provides requirements for testing as well as acceptable leakage criteria. These tests are performed by qualified Appendix J ' test' personnel and utilize calibrated equipment to determine acceptability. Additionally,10 CFR 50.55a(b)(2)(x)(E) requires a general visual examination of the containment each period that would identify any structural degradation that may contribute to leakage. A 'VT-2' visual examination would not provide additional assurance of safety beyond that of current repair / replacement and 10 CFR 50, Appendix J practices.
" Relief is requested in accordance with 10 CFR 50.55a(a)(3)(i). The altemative of pressure testing in accordance with 10 CFR 50, Appendix J, provides an acceptable level of quality and safety. "
1 Evaluation: The Code requires VT-2 visual examination of pressure retaining components following repair, ieplacement, or modification. The licensee has proposed to perform testing and examination of repaired / replaced IWE components in accordance with 10 CFR 50, Appendix J along with the Code-required preservice visual examinations for repairs and replacements.
lWE-5220 requires tests following repair, modification, or replacements. These tests include leakage tests in accordance with the provisions of Title 10, Part 50 of the Code of Federal Regulations, Appendix J, Paragraph IV.A, and visual examination VT-2 in accordance with IWA-5240. The Appendix J tests allow for a certain amount of leakage.
However in accordance with IWE-5250, if the Appendix J leakage rates are exceeded, the source of leakage shall be located and the area shall be examined to the extent necessary to establish the requirements for corrective action. Therefore, it is concluded that the proposed Appendix J testing, along with construction NDE, and preservice visual
5-examination provide an acceptable level of quality and safety and it is recommended that the licensee's proposed alternative be authorized pursuant to 10 CFR 50.55a(a)(3)(i).
2.3 Reauest for Relief RR-lWE4 (Units 1 and 2). IWE-2420(b) And IWE-2420(c).
Successive Examinations After Reoair Code Reauirement: Paragraph IWE-2420(b) requires that when component examination results require evaluation of flaws, evaluation of areas of degradation, or repairs in accordance with IWE-3000, and the component is found to be acceptable for continued service, the areas containing such flaws, degradation, or repairs shall be reexamined during the next inspection period. The reexaminations shall be performed in accordance with Examination Category E-C and at the schedule specified in the inspection requirements of IWE-2411 or IWE-2412.
9 Paragraph IWE-2420(c) requires that when the reexaminations required by Paragraph IWE-2420(b) reveal that the flaws, areas of degradation or repairs remain essentially unchanged for three consecutive inspection periods, the areas containing such flaws, degradation, or repairs no longer require augmented examination in accordance with Table IWE-2500-1, Examination Category E-C.
Licensee's Proposed Alternative: In accordance with 10 CFR 50.55a(a)(3)(ii), the licensee proposed an alternative to the Code successive examination requirements for repairs. The licensee stated:
" Successive examinations in accordance with Paragraphs IWE-2420(b) and IWE-2420(c) are not required for repairs made in accordance with Article IWA-4000".
Licensee's Basis for Prooosed Alternative (as stated):
"The purpose of a repair is to restore the component to an acceptable condition for continued service in accordance with the acceptance standards of Article IWE-3000.
Paragraph IWA-4150 requires the owner to conduct an evaluation of the suitability of the repair including consideration of the cause of f ailure.
"If the repair has restored the component to an acceptable condition, successive examinations are not warranted if the repair was not suitable, then the repair does not meet code requirements and the component is not acceptable for continued service. Neither Paragraph IWB-2420(b), Paragraph IWC-2420(b), nor Paragraph IWD-2420(b) require a repair to be subject to successive examination requirements.
Furthermore, if the repair area is subject to accebrated degradation, it would still require augmented examination in accordance with Table IWE-2500-1, Examination Category E-C. The successive examination of repairs in accordance with Paragraphs IWE-2420(b) and IWE-2420(c) constitutes a hardship without a compensating increase in quality or safety.
"In tt -
esolution to public comment #3.3, the NRC statec' "he purpose of IWE-24"P-:.s to manage components found to be Mceptable to : o'tinued service 4
. (meaning no repair or replacement at this time) as an Examination Category E-C component... If the component had been repaired or replaced, then the more frequent examination would not be needed.
" Relief is requested in accordance with 10 CFR 50.55a(a)(3)(ii). Compliance with the specified requirements of this section would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety."
Evaluatio,1: In accordance with IWE-2420(b) and IWE-2420(c), the Code requires the reexamination of flaws, areas of degradation, or repairs to confirm that they renvain essentially unchanged for three consecutive inspection periods. The licensee contends that performance of successive examination for repairs made in accordance with Article IWA-4000 is a burden without a compensating increase in the level of quality and safety.
IWB-2420(b), lWC 2420(b), and IWD-2420(b) do not require the successive inspection of repairs as required in IWE-2420(b). While the integrity of the containment is critical to nuclear plant safety, the INEEL staff believes that IWB (Class 1), IWC (Class 2), and IWD (Class 3) components are as critical to plant safety as IWE components. Therefore, the INEEL staff believes that the requirement to perform successive examinations on repairs for IWE components is not justified when compared to IWB, IWC and IWD requirements.
Considering that the failure mechanism is identified and corrected as required and the repair receives preservice examinations, performance of the successive examinations presents an unnecessary burden on the licensee without a compensating increase in safety. Therefore, it is recommended that the licensees proposed alternative be authorized pursuant to 10 CFR 50.55a(a)(3)(ii) for repaired components only. For flaws or areas of degradation accepted by evaluation, successive examination are still required.
2.4 Reauest for Relief RR-lWE5 (Units 1 and 2L Examination Cateoorv E-G. Item E8.20.
Pressure Retainina Boltina Code Reauirement: Examination Category E-G, item E8.20, requires a bolt torque or tension test of bolted connections each inspection interval.
Licensee's Pronosed Alternative: In accordance with 10 CFR 50.55a(a)(3), the licensee proposed and alternative to the Code-required bolt torque or tension test.
The licensee stated:
"The following examinations and tests required by Subsection lWE ensure the st:acturalintegrity and the leak-tightness of Class MC pressure retaining bc! ting, and therefore, ha additional examinations are proposed:
(1)
Exposed surfaces of bolted connections will be visually examined in accordance with the requirements of Table IWE-2500-1, Examination Category E-G, Pressure Retaining Bolting, item No. E8.10, and
7 (2)
Bolted connections shall meet the pressure test requirements of Table IWE-2500-1, Examination Category E-P, All Pressure Retaining Components, item E9.40."
Licensee's Basis for Proposed Alternative (as stated):
" Bolt torque or tension testing is required on bolted connections that have not been disassembled and reassenwled during the inspection interval. Determination of the torque or tension value would require that the bolting be un-torqued and then re-torqued or re-tensioned.
"Each penetration receives a 10 CFR 50 Appendix J Type B test in accordance with the testing frequencies specified in Appendix J. As noted in 10 CFR 50 Appendix J, the purpose of Type B tests is to measure leakage of containment penetrations whose design incorporates resilier1 seals, gaskets, sealant compounds, and electrical penetrations fitted with flexible metal seal assemblies. The performance of the Type B test itself proves that the bolt torque or tension remains adequate to provide a leak rate that is within acceptable limits. The torque or tension value of bolting only becomes an issue if the leak rate is excessive. Once a bolt is torqued or tensioned, it is not subject to any dynamic loading that could cause it to experience significant change. Appendix J testing and visualinspection is adequate to demonstrate that the design function is met. Torque or tension testing is not required on any other ASME Section XI, Class 1,2, or 3 bolted connections or their supports as part of the inservice inspection program.
" Relief is requested in accordance with 10 CFR 50.55a(a)(3)(ii). Bolt torque or tension testing of bolted connections which are verified not to experience unacceptable leakage through 10 CFR 50, Appendix J Type B testing is considered to
]
be a hardship or unusual difficulty without a compensating increase in the level of quality and safety."
Evaluation: The Code requires that pressure-retaining botting that has not been disassembled and reassembled during the inspection interval be torque or tension tested.
This examination is used to aid in the determination that the leak tight integrity of the subject bolted connection is maintained. The licensee proposed to use the 10 CFR 50, Appendix J, Type B test as an alternative to the Code requirement to verify the integrity of penetrations with bolted connections.
Containrnent penetration integrity is to be verified by performance of the Code-required visual examination of the bolting in conjunction with the Type B test. It is the opinion of the INEEL staff that bolt torque or tension testing does not provide assurance that a pressure seal exists at a containment penetration and that the Type B test is adequate for assuring that the bolted connection is performing it's designated function. In addition, since torque or tension testing is not required by the Code for Class 1,2 and 3 components, it appears to be unwarranted for Examination Category IWE components.
Therefore, it is concluded that the licensee's proposed alernative provides an acceptable level of quality and safety since Type B testing provides the final verification of an
4 8-acceptable pressure seal at the containment penetration while the integrity of the bolting itself is verified by the Code-required VT-1 visual examination. Based on the assurances provided by the existing Code-required VT-1 visual examinations, and the leak-rate determinations provided by Appendix J, Type B tests, it is recommended that the licensee's proposed alternative be authorized pursuant to 10 CFR 50.55a(a)(3)(i).
2.5 Reauest for Relief RR-lWE6 (Units 1 and 2. Subarticle IWE-2500(c)(3). Auamented 111trasonic Thickness Measurements Code Reauirement: IWE-2500(c)(3) requires that when ultrasonic thickness measurements are performed, one foot square grids shall be used. The number and location of the grids shall be determined by the owner. IWE-2500(c)(4) requires the minimum wall thickness within each grid to be determined.
Licensee's Proposed Alternative: In accordance with 10 CFR 50.55a(a)(3)(ii), the licensee proposed an alternative to using one foot square grids for augmented examination areas and the requirement to determine the minimum wall thickness within each grid. The licensee stated:
" Table RR-lWE6 will be used to determine examination requirements for ultrasonic thickness measurements of areas requiring augmented examination."
Licensee's Basis for Proposed Alternative (as stated):
"Subarticles IWE-2500(c)(3) and IWE-2500(c)(4) of the 1992 Edition,1992 Addends of ASME Section XI requires that the minimum thickness within each one foot square grid of surf ace areas requiring augmented examination be marked such that periodk reexamination of that location can be performed. Thickness readings are point readings. Numerous readings are necessary to identify the minimum thickness within each grid. This only identifies the thinnest area. Periodic examination of the i
minimum thickness point only monitors that point. It may not be the area that is the most susceptible to accelerated degradation.
" Table RR-lWE6 (attached)' provides an alternative to the one foot square grid area required by IWE-2500(c)(3). Table RR-lWE6 requires examination at the grid line intersections. The grid line intersections may not exceed 12 inches and may be as small as 2 inches".
"For a sample area of 50 square feet, Table RR-lWE6 requires a minimum of 100 locations be monitored. For a sample area of 50 square feet, IWE-2500(c)(3) would require only 50 locations be monitored. In this instance, using Table RR-lWE6 would require monitoring more locations than required by IWE-2500(c"3).
1 Equivalent to Table -2500-2 of Code Case N-605, A/ternative to the requirements ofIWE-2500(c) for Augmented Examination of Surface AreasSection XI, Division 1.
9 "For sample areas greater than 100 square feet, Table RR-lWE6 requires that sufficient paints be monitored to ensure at least a 95% confidence level that the thickness of the base metalis reduced by no more than 10% of the nominal plate thickness at 95% of the grid line intersections. Table RR-lWE6 also requires additional examinations when any measurements reveal that wall thickness has been reduced by more than 10% of the nominal plate thickness.
"For each examination area, should the measurements at a grid line intersection reveal that the base material is reduced by more than 10% of the nominal plate j
thickness, Table RR-lWE6 requires the minimum wall thickness within each adjoining grid be determined. This is similar to the examination requirements of IWE-2500(c)(4) except that Table RR-lWE6 focuses resources on areas that have exhibited degradation rather than areas that have no exhibited degradation.
"The Flow Accelerated Corrosion Program presently in place has proven that thickness readings taken at grid intersections are effective in monitoring wall thinning of piping.
" Relief is requested in accordance with 10 CFR 50.55a(a)(3)(ii). Taking numerous ultrasonic thickness readings within a grid that has not exhibited degradation results in hardship or unusual difficulty without a compensating increase in the level of quality and safety."
Evaluation: IWE-2500(c)(3) requkes that when ultrasonic thickness measurements are performed, one foot square grids shall be used. The number and location of the grids shall I
be determined by the owner. Additionally, IWE-2500(c)(4), requires that ultrasonic measurements be used to determine the minimum wall thickness within each grid (this essentially relates to 100% volumetric examination coverage). The location of the minimum wall thickness shall be marked such that periodic reexamination of that location can be performed.
l The licensee has proposed an alternative essentially equivalent to Code Cese N-605, Alternative to the Requirements ofIWE-2500(c) for Augmented Examination of Surface Areas. Code Case N-605 requires that when ultrasonic thickness measurements are performed, grids shall be used and ultrasonic examinations shall be performed at the grid line intersections. Grid line spacing shall not exceed 12 inches and need not be less than 2 inches. For examination areas less than 100 square feet, grid line spacing shall be selected such that a minimum of 100 measurements are obtained, unless this requires selecting a l
grid line spacing of less than 2 inches. For examination areas greater than 100 sc,uare feet, the Code Case requires that sufficient points be monitored to ensure at least a 95%
confidence level that the thickness of the base metal is reduced by no more than 10% of I
the nominal plate thickness at 95% of the grid line intersections. Additionally, when an ultrasonic measurement performed at a grid line intersection reveals that the thickness of the base metalis reduced by more than 10% of the nominal plate thickness, the minimum wail thickness shall be determined and located within each adjoining grid.
I l
i i
I
.- In order for the licensee to meet the Code requirements the licensee would be required to perform essentially 100% volumetric examination coverage in each grid of the augmented examination area to determine the minimum wall thickness. On augmented examination areas, the requirement to perform 100% volumetric examinations coverage, could prove to be unrealistic in terms of the size of tha area to be examined and the time required to perform the examinations. Both time and size of the examinations to be performed would relate directly to the additional potential radiation exposure that plant personnel would be exposed to by performance of 100% examination coverage. Subjecting the licensee to this requirement would result in a significant burden without a compensating increase in quality and safety. The INEEL staff believes that the proposed alternative provides a sampling methodology similar to that of other Code requirements, and other erosion / corrosion monitoring programs utilized throughout the industry. Therefore, it is concluded that the licensees proposed alternative will provide reasonable assurance of structuralintegrity and should be authorized pursuant to 10 CFR 50.55a(a)(3)(ii).
2.6 Reauest for Relief RR-lWL2 (Units 1 and 2L IWA-2210 Visual Examination Reauirements of IWE Comoonents I
Code Reauirement: IWA-2210 specifies the requirements associated with visual examinations, including illumination requirements and maximum examination distances for direct and remote VT-1, VT-2, and VT-3 examinations. Specifically, the Code requires minimum iliumination of 50 Footcandits (Fc), maximum direct i
examination distances of 4 ft. and maximum procedure demonstration character height of 0.105 inch to perform a direct VT-3 visual examination.
Licensee's Proposed Alternative: In accordance with 10 CFR 50.55a(a)(3)(ii), the licensee proposed an alternative to the requirements of l'NA-2210 of the 1992 Addenda. As an alternative, the licensee proposed to use the requirements of the 1989 Edition of Section XI for VT-3 visual examinations. The licensee stated:
"VT-3C visual examinations will be performed under distance and illumination requirements necessary to detect the conditions or indications for which the visual examination is performed. The procedure will be demonstrated capable of detecting conditions or indications for which the examination is being performed".
Licensee's Basis for Proposed Alternative (as stated):
"In addition to the requirements of Subsection IWL, the requirements of the 1992 Edition,1992 Addenda of Gubsection IWA for containment examinations are applicable.
"For VT-3C examinations performed in accordance with Subsection IWL, the examination distance and illumination requirements are the same for that specified for VT-3 in Table IWA-2210-1. For remote examination of IWE componeras,10 CFR 50.55a permits the maximum direct examination distance specified in Table IWA-2210-1 to be extended and the minimum illumination requirements specified in Table IWA-2210-1 to be decreased provided that the conditions or indications for which the
. visual examination is performed can be detected at the chosen distance and illumination. This amendment to the requirements of Table IWA-2210-1 can be extended to examination of IWL items provided the indications for which the visual examination is performed can be detected at the chosen distance and illumination.
" Relief is requested in accordance with 10 CFR 50.55a(a)(3)(ii). Compliance with the specified requirements of this section would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety."
Evaluation: To comply with the expedited examination of containment requirements of 10 CFF 50.55a(g)(6)(ii)(.8), licensees must perform visual examinations on Class MC and Metallic Liners of Class CC Concrete Components of Light-Water Cooled Plants per the requirements of IWE. These examinations are to be performed to the requirements of the 1992 Edition with the 1992 Addenda of ASME XI. As an alternative to the Code visual examination requirements, the licensee proposed to extend the requirements of 10 CFR 50.55a(b)(2)(x)(B) for IWE components and perform the visual examination using distance 1
and illumination requirements necessary to detect the conditions or indications for which j
the visual examination is performed. For remote visual examination of IWE components, i
10 CFR 50.55a(b)(2)(x)(B) circumvents Code requirements and permits the maximum direct examination distance specified in Table IWA-2210-1 to be extended and the minimum illumination requirements specified in Table IWA-2210-1 to be decreased provided that the conditions or indications for which the visual examination is performed can be detected at the chosen distance and illumination.
I The Regulation allows some latitude in the distance and illumination requirements for remote visual examination of IWE components. However, as an alternative to the Code requirements for other ccmponents, it is poorly defined and not adequately justified.
Therefore, the licensee's proposed alternative should not be authorized. To be found acceptable, the licensee must provide specific information defining the relevant conditions and indications and describe how the effectiveness of the visual procedures will be demonstrated.
3.
.Q,0NCLUSION i
The INEEL sta i has reviewed the licensee's submittal and concludes that for Requests for Relief Nos. Rif-lWE3 (Unit 1 only) and RR-lWE5, the licensee's proposed alternatives will provide an ac~ eptable level of quality and safety. Therefore, it is recommended that these c
proposed alternatives be authorized for the second 10-year interval pursuant to 10 CFR 50.55ala)(3)(i). For Requests for Relief Nos. RR-lWE2, RR-lWE4 and RR-lWE6, it is concluded that comp!iance with the Code requirements would result in a burden without a compensating increase in the level of quality and safety and that the licensee's proposed alternatives will provide reasonable assurance of operational readiness. Therefore, it is recommended that these proposed alternatives be authorized for the second 10-year interval pursuant to 10 CFR 50.55a(a)(3)(ii). For Requests for Relief RR-lWL2, the licensee's proposed alternative does not provide an acceptable level of quality and safety.
Therefore, it is recommended that the proposed alternatives not be authorized.
m