ML15112A697
| ML15112A697 | |
| Person / Time | |
|---|---|
| Site: | Oconee, Mcguire, Catawba, McGuire  |
| Issue date: | 11/25/1998 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML15112A696 | List: |
| References | |
| NUDOCS 9811300108 | |
| Download: ML15112A697 (8) | |
Text
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 2055-001 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELIEF REQUEST FROM ASME CODE SECTION XI REQUIREMENTS DUKE ENERGY CORPORATION CATAWBA NUCLEAR STATION, UNITS 1 AND 2 MCGUIRE NUCLEAR STATION, UNITS 1 AND 2 OCONEE NUCLEAR STATION, UNITS 1. 2. AND 3 DOCKET NOS. 50-413, 50-414, 50-369, 50-370, 50-269, 50-270, AND 50-287
1.0 INTRODUCTION
Pursuant to Title 10 of the Code of Federal Regulations (10 CFR) Section 50.55a(g), the inservice inspection (ISI) of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code) Class 1, 2, and 3, components at the Catawba Nuclear Station, Units 1 and 2 (Catawba), McGuire Nuclear Station, Units 1 and 2 (McGuire), and Oconee Nuclear Station, Units 1, 2, and 3 (Oconee), shall be performed in accordance with Section XI of the ASME Code and applicable Addenda, except where relief has been granted by the Commission pursuant to 10 CFR 50.55a(g)(6)(i). Section 50.55a(a)(3) states that alternatives to the requirements of paragraph (g) may be used, when authorized by NRC if (i) the proposed alternative provides an acceptable level of quality and safety or (ii) compliance with the specified requirements would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety.
As published In the Federal Register (No. 154, Volume 61, dated August 8, 1996), the U.S. Nuclear Regulatory Commission (NRC) announced an amendment to its regulation of 10 CFR Part 50, Section 50.55a (rule). The rule incorporated, by reference, the 1992 Edition with 1992 Addenda of Subsections IWE and IWL of Section XI of the ASME Code. Subsections IWE and IWL provide the requirements for ISI of Class CC (concrete containments) and Class MC (metallic containments) of light-water cooled power plants. The effective date for the amended rule was September 9, 1996, which requires licensees to incorporate the new requirements into their 11 plans and to complete the first containment inspection by September 9, 2001. However, a licensee can submit a request for relief from one or more requirements of the regulation (or the endorsed Code requirements) with proper justification.
In accordance with 10 CFR 50.55a(g)(6)(ii)(B), all licensees shall implement the inservice examinations specified for the first period of the first inspection interval in Subsection IWE, 9811300108 981125 PDR ADOCK 05000269 P
-2 Requirements For Class MC and Metallic Liners of Class CC Concrete Components of Light-Water Cooled Plants, of the 1992 Edition with the 1992 Addenda in conjunction with the requirements of 10 CFR 50.55a(b)(2)(ix) by September 9, 2001. Licensees shall also implement the inservice examinations that correspond to the number of years of operation that are specified in Subsection IWL, Requirements For Class CC Concrete Components of Light Water Cooled Plants, of the 1992 Edition with the 1992 Addenda in conjunction with the requirements of 10 CFR 50.55a(b)(2)(ix) by September 9, 2001.
The Code of record for the Catawba Nuclear Station, Units 1 and 2, second 10-year interval, the McGuire Nuclear Station, Units 1 and 2, second 10-year interval, and Oconee Nuclear Station, Units 1, 2, and 3, third 10-year interval, is the 1989 Edition of Section XI of the ASME Code. Duke Energy Corporation (DEC, the licensee) is developing the containment ISI programs of the subject plants in accordance with the requirements of Subsections IWE and IWL of the 1992 Edition, 1992 Addenda of Section XI, as required by 10 CFR 50.55a(b)(2),
50.55a(g)(4)(r) and 50.55a(g)(6)(ii)(B).
By letter dated May 28, 1998, DEC submitted Request for Relief No. 98-GO-004, seeking relief from the expedited examination of containment required by 10 CFR 50.55a(g)(6)(ii)(B) and the requirements of the ASME Code,Section XI, for the Catawba Nuclear Station, Units 1 and 2, second 10-year interval, the McGuire Nuclear Station, Units 1 and 2, second 10-year interval, and the Oconee Nuclear Station, Units 1, 2, and 3, third 10-year interval. By letter dated July 29, 1998, the licensee responded to an NRC request for additional information and provided a revised version of 98-GO-004.
2.0 DISCUSSION 2.1 Regulatory Requirement See Section 1.0.
2.2 Code Requirement 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 licensee requests relief from the following requirements (as stated):
- a.
The requirement of IWA-2210 to demonstrate by procedure that direct visual examinations can resolve the specified lower case characters at minimum illumination levels specified in Table IWA-2210-1 as follows.
Visual Minimum Maximum Direct Maximum Procedure Examination Illumination Examination Demonstration Lower fc Distance, ft Case Character Height, in.
VT-1 50 2
0.044
-3 VT-2 15 6
0.158 VT-3 50 4
0.105
- b.
The requirement of IWA-2210 to measure illumination levels on examination surfaces.
- c.
The requirement of IWA-2210 to measure illumination levels from battery powered portable lights at an interval not exceeding 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />.
- d.
The requirement of IWA-2210 to check the illumination levels of battery powered portable lights before and after each examination or series of examinations.
- e.
The requirement of IWL-231 0(a) and (b) that, for VT-1 C and VT-3C visual examinations, the minimum illumination, maximum direct examination distance, and maximum procedure demonstration lower case character height shall be as specified in IWA-2210 for VT-1 and VT-3 visual examinations.
2.3 Alternative Examination(s): (as stated by licensee)
In lieu of the requirements of IWA-221 0 and IWL-231 0, the following alternative is proposed:
IWA-2210 VISUAL EXAMINATIONS IWA-221 1 VT-1 and VT-1C Examinations (a) VT-1 examinations are conducted to detect discontinuities and imperfections on the surfaces of components, including such conditions as cracks, wear, corrosion, erosion, physical damage or degradation, and conditions identified in IWE-3500. VT-1C examinations are conducted in accordance with IWL-231 0(a).
(b) Direct VT-1 and VT-1C examinations may be conducted when access is sufficient to place the eye within 24 in. of the surface to be examined and at an angle not less than 30 deg. to the surface. Mirrors may be used to improve the angle of vision. The examination, using natural or artificial lighting, shall be sufficient to resolve a 1/64 in. black line on an 18 percent neutral gray card..
(c) Remote VT-1 and VT-1C examinations may be substituted for direct examination. Remote examination may use aids, such as telescopes, borescopes, fiber optics, cameras, or other suitable instruments, provided such systems have a resolution capability at least equivalent to that attainable by direct visual examination.
-4 IWA-2212 VT-2 Examination (a) 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 system pressure tests.
(b) VT-2 examinations shall be conducted in accordance with IWA-5000. The examination, using natural or artificial lighting, shall be sufficient to resolve a 1/32 in. black line on an 18 percent neutral gray card.
IWA-2213 VT-3 and VT-3C Examinations (a) VT-3 examinations are conducted to determine the general mechanical and structural condition of components and their supports by verifying parameters such as clearances, settings, and physical displacements; and to detect discontinuities and imperfections, such as loss of integrity at bolted or welded connections, loose or missing parts, debris, corrosion, wear, erosion, or other degradation, and conditions identified in IWE-3500. VT-3C examinations are conducted in accordance with IWL-2310(b).
(b) VT-3 includes examinations for conditions that could affect operability or functional adequacy of snubbers and constant load and spring type supports.
(c) VT-3 and VT-3C examinations may be performed directly or remotely, and may use aids, such as telescopes, borescopes, fiber optics, cameras, or other suitable instruments. The examination, using natural or artificial lighting, shall be sufficient to resolve a 1/32 in. black line on an 18 percent neutral gray card.
IWA-2215 Replication Surface replication methods may be used for VT-1, VT-1 C, VT-3, and VT-3C examinations when the surface resolution is at least equivalent to that of direct visual observation.
IWL-2310 Visual Examination And Personnel Qualification (a) VT-1C visual examinations are conducted to determine concrete deterioration and distress for suspect areas detected by VT-3C, and conditions (e.g., cracks, wear, or corrosion) of tendon anchorage and wires or strands.
(b) VT-3C visual examinations are conducted to determine the general structural condition of concrete surfaces by identifying areas of concrete deterioration and distress, such as defined in ACI 201.1.
-5 (c) The Owner's written practice shall define qualification requirements for concrete examination personnel in accordance with IWA-2300. Limited certification in accordance with IWA-2350 may be used for examiners limited to concrete.
2.4 Licensee's Basis for Proposed Alternative (as stated):
Background:
The ASME Boiler and Pressure Code,Section XI, Division 1, 1992 Edition with the 1992 Addenda, IWA-2210, requires that direct visual examinations be demonstrated by procedure to resolve the selected test chart characters of Table IWA-2210-1 at the maximum examination distance using minimum illumination levels specified in Table IWA-2210-1. Remote visual examinations are required to be demonstrated to resolve the selected test chart characters specified in Table IWA-2210-1 using the minimum illumination levels specified in Table IWA-2210-1, regardless of examination distance. These requirements are excessive for remote visual examination of containments which may be performed at considerable distances from the examination surfaces. Also, the criteria requiring resolution of lower case characters of the size specified in Table IWA-2210-1 is overly prescriptive for examinations which are performed to detect the types of conditions required by Subsections IWE and IWL. Relevant indications on containment surfaces can be detected using criteria which is less stringent than that specified in IWA-2210. The proposed alternative is sufficient to ensure that visual examinations are capable of detecting conditions for which the examinations are performed.
IWA-2210 also specifies requirements for use of portable lighting and measurement of illumination levels on examination surfaces. Illumination levels are required to be examined on each examination surface, except when the same portable lighting source is used. If battery powered portable lights are used, the illumination levels are required to be checked before and after each examination or series of examinations, but shall not exceed 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> between checks. While sufficient illumination is necessary to perform an adequate examination, measurement of illumination levels on all examination surfaces will be difficult for those surfaces which are at considerable distance and are not readily accessible. Also, due to the extent of required examinations, the 4 hour4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> limitation on use of battery powered light sources will require suspending examinations solely to recheck-illumination levels, and may impact ALARA goals. This provision is unnecessary if it can be demonstrated that illumination levels of lighting are adequate during the performance of examinations, regardless of the length of time the portable lighting source is used.
IWL-2310(a) and (b) also specify that the minimum illumination, maximum direct examination distance, and maximum procedure demonstration lower case character height shall be as specified in IWA-2210 for VT-1C and VT-3C visual
-6 examinations. In addition to the proposed alternative to IWA-2210, this request also proposes an alternative to these requirements.
The above requirements create a hardship or unusual difficulty without a compensating increase in the level of quality and safety. The proposed alternative provides a reasonable, appropriate alternative to the Code requirements. Visual examinations shall be demonstrated to be capable of detecting conditions for which the examination is performed, providing and acceptable level of quality and safety to that obtainable by IWA-2210 and IWL-2310(a) and (b).
Basis for Requesting Alternative:
10 CFR 50.55a(b)(2)(x)(B) allows an alternative to the minimum illumination and maximum examination distance requirements of Table IWA-2210-1 for remote visual examinations performed in accordance with IWE only. As a result, remote visual examinations of concrete containments under IWL must be demonstrated to meet the requirements of IWA-2210. Compliance with this requirement to resolve the specified test chart characters at typical examination distances needed for concrete surface examinations may be difficult and is excessive when the VT-3C examination can be demonstrated by procedure to be able to detect conditions for which the examination is performed.
For direct visual examination of Class MC and Class CC components, the requirements of IWA-2210 and IWL-2310(a) and (b) are unnecessary, provided the direct visual examination can also be demonstrated to be capable of detecting conditions for which these examinations are performed.
For Class MC applications, it is anticipated that most surfaces will require remote visual examination because of structural geometry which make access within the Table IWA-2210-1 distances difficult. Because 10 CFR 50.55a(b)(2)(x)(B) allows the maximum remote examination distance to be extended and the minimum illumination decreased, compliance with lighting and examination distance requirements of Table IWA-2210-1 need not be met for remote VT-3 visual examinations conducted at distances exceeding 4 feet. It is unnecessary to require that a direct visual examination performed on a surface at a distance less than 4 feet comply with the requirements of Table IWA-2210-1 when a remote visual examination of that same surface is permitted to be performed using lower illumination levels at distances exceeding 4 feet, provided the illumination is sufficient and the resolution adequate to detect conditions for which the examination is performed.
The requirement of IWA-2210 to check illumination levels from battery powered portable lights at intervals not exceeding 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> is excessive and unnecessary.
Because of the length of time it typically requires to access certain containment surfaces and perform examinations, it is a hardship to require that illumination levels be checked at this frequency. The imposition of an arbitrary 4 hour4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> limit is inappropriate when it can be otherwise demonstrated that sufficient illumination is
-7 provided during the examination or series of examinations. Compliance with the 4 hour4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> limitation will increase the amount of time required to perform examinations and will result in'additional personnel radiological exposure, without any increase in the level of quality of the examinations. Also, if a portable lighting source becomes contaminated, during the course of an examination it may be difficult to transport the lighting source to a location where the illumination level on this equipment can be checked within the maximum 4 hour4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> limit.
The requirement of IWA-2210 to check illumination levels of battery powered light sources before and after each examination or series of examinations is unnecessary, provided the visual examinations can be demonstrated to be capable of detecting conditions for which these examinations are performed.
Justification for Granting of Alternative:
The purpose of IWA-2210 and IWL-2310(a) and (b) is to ensure that visual examinations are performed in a consistent manner that is capable of detecting the conditions for which the examination is performed. The proposed alternative has been determined to satisfy this purpose,. but eliminates requirements that are either inappropriate or unnecessary for visual examination of Class MC and Class CC components. This alternative requires that visual examinations be demonstrated to be capable of detecting conditions for which the examinations are conducted.
Resolutions of a 1/64 in. or 1/32 in. black line on an 18% neutral gray card as specified in this alternative provides an acceptable method for demonstrating direct and remote visual examinations, without requiring measurement of lighting illumination levels. The use of this alternative will allow direct visual examinations to be performed at distances which exceed those specified in Table IWA-2210-1, but which are practical for containment examination. This alternative will also help to minimize radiological exposure to examination personnel.
3.0 EVALUATION To comply with the expedited examination of containment requirements of 10 CFR 50.55a(g)(6)(ii)(B), licensees must perform visual examinations on Class MC and Metallic Liners of Class CC Concrete Components of Light-Water Cooled Plants in accordance with the requirements of IWE, and visual examinations on Class CC Concrete Components of Light-Water Cooled Plants in accordance with the requirements of IWL.
Each of the Code requirements for which DEC is proposing an alternative applies to measurement of lighting illumination and examination distance. The visual examinations on containment are performed to determine if damage or degradation, including cracks, wear, corrosion, erosion, or other physical damage, warrant additional evaluation or repair of the structure. In order for the visual examinations to be performed in such a way to detect the critical flaws, proper lighting is essential. The licensee has provided an alternative to the Code requirements, in part, employing the use of natural or artificial lighting capable of resolving a 1/32 inch (VT-2, direct or remote VT-3 examinations), or 1/64 inch (direct or remote VT-1 examination) wide line on a 18 percent neutral gray card placed on the examination surface.
-8 While the use of the neutral gray card does not result in a quantitative evaluation of the illumination, it provides a method to verify that a 1/32 inch or 1/64 inch wide flaw is visually detectable. The NRC staff believes that the artificial flaw (black line) located on the 18 percent neutral gray card, when placed on the examination surface, provides an appropriate simulation in terms of the size of the flaws sought. It is reasonable to conclude that visual verification, via direct or remote means, of the artificial flaw on the 18 percent neutral gray card placed on the examination surface provides sufficient evidence of adequate illumination and examination distance. Based on this discussion, the staff agrees that the licensee's proposed alternative provides an acceptable level of quality and safety in that the examinations will be capable of detecting degradation.
4.0 CONCLUSION
Based on the information provided by the licensee in the relief request, the staff concludes that the licensee's proposed alternative will provide an acceptable level of quality and safety.
Therefore, this proposed alternative is authorized, pursuant to 10 CFR 50.55a(a)(3)(i), for the Catawba Nuclear Station, Units 1 and 2, second 10-year interval, the McGuire Nuclear Station, Units 1 and 2, second 10-year interval, and the Oconee Nuclear Station, Units 1, 2, and 3, third 10-year interval.
Principal Contributor: Hans Ashar Date: November 25, 1998