ML14183A929
| ML14183A929 | |
| Person / Time | |
|---|---|
| Site: | Robinson  |
| Issue date: | 07/26/1999 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML14183A928 | List: |
| References | |
| NUDOCS 9908020011 | |
| Download: ML14183A929 (22) | |
Text
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-001 SAFETY EVALUATION OF RELIEF REQUESTS FROM ASME SECTION XI REQUIREMENTS FOR CONTAINMENT INSPECTION H. B. ROBINSON STEAM ELECTRIC PLANT, UNIT 2 DOCKET NO.: 50-261
1.0 INTRODUCTION
In the Federal Register dated August 8, 1996 (61 FR 41303), the Nuclear Regulatory Commission (NRC) amended its regulations to incorporate by reference the 1992 edition with 1992 addenda of Subsections IWE and IWL of Section XI of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel (B&PV) Code (Code). Subsections IWE and IWL provide the requirements for inservice inspection (ISI) of Class CC (concrete containment),
and Class MC (metallic containment) of light-water cooled power plants. The effective date for the amended rule was September 9, 1996, and it requires the licensees to incorporate the new requirements into their ISI plans and to complete the first containment inspection by September 9, 2001. However, a licensee may propose alternatives to or submit a request for relief from the requirements of the regulation pursuant to 10 CFR 50.55a(a)(3) and (g)(5).
By letters dated January 20 and June 25, 1999 (References 1 and 2), the licensee, Carolina Power and Light Company, proposed several alternatives to the requirements of Subsections IWE and IWL of Section XI of the ASME Code for its H. B. Robinson Steam Electric Plant (HBRSEP), Unit No. 2. The NRC's findings with respect to authorizing the alternatives or denying the proposed requests are discussed in this evaluation.
2.0 EVALUATION 2.1 RELIEF REQUEST IWE/IWL-01 2.1.1 Code Requirements:
ASME B&PV Code, 1992 Edition, 1992 Addenda,Section XI, Table IWE-2500-1, "Examination Categories" Examination Category E-A, requires a visual examination of 100% of the accessible surface areas of containment in accordance with paragraphs IWE-3510.2, 'Visual Examinations on Coated Areas," and IWE-3510.3, "VT-3 Visual Examinations on Non-coated Areas," for Class MC, and metallic liners of Class CC components.
The required examination method for these examinations is a VT-3 examination. One examination per 10-year ISI interval is required at the end of the inspection interval.
9908020011 990726 PDR ADOCK 05000261 P
2.1.2 ' Specific Relief Requested:
Relief is requested from performing VT-3 examinations, in accordance with ASME B&PV Code, 1992 Edition, 1992 Addenda, Table IWE-2500-1, Examination Category E-A, on the surface areas of the containment liner which are insulated. It is proposed to perform a VT-3 examination on those portions of the insulated containment liner that are exposed when a maintenance activity requires removal of the liner insulation.
This request for relief is applicable to the insulated portion of the containment liner classified as Class MC and subject to the requirements of Table IWE-2500-1, Examination Category E-A, at HBRSEP, Unit 2.
2.1.3 Alternative Examination(s):
The alternative examination proposed is to perform a VT-3 examination on those portions of the insulated containment liner that are exposed when a maintenance activity requires removal of the liner insulation. This examination will be completed if not previously performed in the inspection interval.
Prior to Refuel Outage (RO) 18 in 1998, a project was initiated to remove some of the insulation panels to inspect the containment liner for potential corrosion. The size of the typical panel is approximately 3'-8" x 7'-8". The results of the inspection revealed that on the containment liner at various locations on the lowest row of sheathing panels, the coating had degraded and that there was some amount of corrosion of the containment liner. The evaluated thickness of the containment liner was greater than the minimum design thickness. It was also noted that for those sheathing panels removed above the lowest row, the coating degradation was less and the corrosion of the containment liner was minimal. It was concluded that the primary cause of the corrosion was a 1975 event that resulted in at least 12 inches of water on the containment floor.
Therefore, a decision was made to remove the accessible sheathing panels on the lowest row to inspect the containment liner for potential corrosion and to repair degraded coatings. This inspection and repair will continue in RO 19 in 1999 and be completed in RO 20 in 2001. Of approximately 58 panels on the lowest row of sheathing, 18 panels were removed in RO 18, approximately 24 panels are planned to be removed in RO 19, and approximately 16 panels are planned to be removed in RO 20. A small number of these panels may not be able to be removed because of obstructions or high radiation areas. When the removal, inspection, and recoating of this lowest row of panels are complete, corrosion due to the 1975 event will be arrested and the corrective action will be complete.
In addition to the lowest row of panels, additional panels at various locations and elevations have been and will be removed to accommodate maintenance during outages. This would bring the total number of sheathing panels removed during these three outages to approximately one hundred (100). The total of sheathing panels on containment is estimated to be approximately 2000.
2
2.1.4 Basis for Requestinq Relief:
In accordance with 10 CFR 50.55a(a)(3)(i), relief is requested for HBRSEP, Unit No. 2 on the basis that the proposed alternatives in conjunction with the examinations that have occurred during RO 18 and the examinations that will occur during RO 19 and RO 20 would provide an acceptable level of quality and safety.
2.1.5 Justification for Granting Relief:
Relief is requested from the Code requirements for VT-3 examinations of the containment liner in areas that are insulated. Alternative examinations stated below provide an acceptable level of quality and safety.
The containment liner at HBRSEP, Unit No. 2 is covered by insulation and stainless steel sheathing. This insulation and sheathing form part of the defense-in-depth philosophy of the containment liner at HBRSEP. The three barriers that protect the containment liner pressure boundary are as follows:
- 1. Insulation and sheathing
- 2. Coating
- 3. Containment liner thickness Although not technically complex, the removal of sheathing panels to inspect the containment liner is intrusive to the design of this moisture barrier and expends significant resources. In RO 18 approximately 35 man-hours were expended per panel. These resources do not include project management time, scaffolding hours, or potential critical path polar crane time.
Specifically, one of the panels required use of the crane to erect a scaffold. Inspection and repair of this sheathing panel required approximately 28 hours3.240741e-4 days <br />0.00778 hours <br />4.62963e-5 weeks <br />1.0654e-5 months <br /> of scheduled polar crane time.
Based on the defense-in-depth design of the containment liner and the inspections that have been completed, and will occur during RO 19 and RO 20, the inspection of the containment liner behind those areas of the containment liner that are insulated is not warranted, unless the sheathing panels are removed for maintenance purposes.
The proposed examination provides an acceptable level of quality and safety without presenting an undue challenge to the moisture barrier insulation panels.
2.1.6 Staff Evaluation of IWE/IWL-01:
In lieu of performing VT-3 examinations, in accordance with ASME B&PV Code, 1992 Edition, 1992 Addenda, Table IWE-2500-1, Examination Category E-A, on the surface areas of the containment liner which are insulated, the licensee proposed an alternative which involves the performance of a VT-3 examination on those portions of the insulated containment liner that are exposed when a maintenance activity requires removal of the liner insulation.
According to the licensee, a total of 44 sheathing panels (18 on the lowest row and 26 at various locations) were removed to inspect for corrosion. The results of inspection showed that the 3
containment liner coating at various locations of the lowest row sheathing panels had degraded and some amount of containment liner corrosion was identified. However, the thickness of the containment liner was found to be greater than the minimum design thickness. The inspection results also showed that for those sheathing panels removed above the lowest row, the liner coating degradation was less and the liner corrosion was minimal. During the next two refueling outages (RO 19 to be completed in 1999 and RO 20 to be completed in 2001), the licensee plans to remove the remaining 40 sheathing panels on the lowest row (the total number of sheathing panels on the lowest row is 58) for the liner inspection. In addition to the lowest row of panels, additional panels at various locations and elevations have and will be removed for inspection during these three outages. The sample size of total selected panels (removed and to be removed) is in the range of 5 percent. The licensee also claimed that the removal and reinstallation of sheathing panels are time consuming and will result in hardship and unusual difficulty. Based on the inspection programs and findings described above, the licensee summarized that the proposed alternatives would provide an acceptable level of quality and safety.
Based on the findings of approximate 5 percent sample inspected (as described above), the staff finds that the proposed alternatives (to perform a VT-3 examination on those portions of the insulated containment liner that are exposed when a maintenance activity requires removal of the liner insulation) in conjunction with the examinations that have been completed during RO 18 and the examinations that will be performed during RO 19 and RO 20 would provide an acceptable level of quality and safety. Therefore, the staff concludes that the alternative proposed by the licensee is authorized pursuant to 10 CFR 50.55a(a)(3)(i).
2.2 RELIEF REQUEST IWE/IWL-02 2.2.1 Code Requirements:
The ASME B&PV Code, 1992 Edition, 1992 Addenda,Section XI, Table IWE-2500-1, "Examination Categories," Examination Category E-D, requires a visual examination of the containment moisture barrier, in accordance with Figure IWE-2500-2, "Examination Areas for Moisture Barriers," for Class MC, and metallic liners of Class CC, components.
The required method is a VT-3 examination. One examination per 10-year ISI interval is required. Deferral of the test to the end of the interval is not permitted.
2.2.2 Specific Relief Requested:
Relief is requested from performing VT-3 examinations, in accordance with ASME B&PV Code, 1992 Edition, 1992 Addenda, Table IWE-2500-1, Examination Category E-D, on the containment moisture barriers. In lieu of this requirement, it is proposed that a VT-3 examination of the containment moisture barrier be performed when maintenance activities require removal of the liner insulation.
This request for relief is applicable to components classified as Class MC and subject to the requirements of Table IWE-2500-1, Examination Category E-D, at HBRSEP, Unit 2.
4
2.2.3 Alternative Examination(s):
The alternative examination to the 10-year VT-3 examination of containment moisture barriers is to perform a VT-3 examination on those portions of the 228-foot elevation concrete-metal liner moisture barrier that are exposed when a maintenance activity requires removal of the associated barrier insulation.
During the last refueling outage, RO 18, 18 insulation panels at the 228-foot elevation were removed and the moisture barrier at the 228-foot elevation was visible. The moisture barrier was removed to allow inspection of the containment liner adjacent to the moisture barrier. The containment liner adjacent to the moisture barrier did not show evidence of corrosion, indicating that the moisture barrier was performing its function.
Based on the inspection in RO 18, a decision was made to remove the sheathing panels on the lowest row to inspect for corrosion. A small number of these panels may not be able to be removed because of obstructions or high radiation areas. This inspection of the moisture barrier will be completed in RO 19 and RO 20.
2.2.4 Basis for Requesting Relief:
In accordance with 10 CFR 50.55a(a)(3)(i), relief is requested for HBRSEP, Unit No. 2 on the basis that the proposed alternatives would provide an acceptable level of quality and safety.
As shown in Figure IWE-2500-2 and noted in Table IWE-2500-1, moisture barrier materials at concrete-to-metal interfaces are intended to prevent intrusion of moisture against the pressure retaining metal containment shell or liner. For HBRSEP, Unit No. 2, the moisture barrier that meets this definition is the epoxy joint filler that interfaces with the concrete-to-containment liner interface at the 228-foot elevation. This moisture barrier is covered with insulation that provides an additional moisture barrier. The specification for the insulation requires the exposed surface be impervious to water; suitable water seals at points where the insulation ends are exposed to containment atmosphere; and sealant use to prevent water leakage to the containment liner.
The combination of the epoxy joint filler moisture barrier and the impervious insulation, in conjunction with the examinations that have occurred during RO 18 in 1998 and the examinations that will occur during RO 19 in 1999 and RO 20 in 2001, provide an acceptable level of quality and safety.
2.2.5 Justification for Granting Relief:
The containment internal moisture barrier is covered with an additional layer of insulation and stainless steel sheathing. The specification for the additional layer of insulation and stainless steel sheathing requires that the exposed surface be impervious to water, suitable water seals at points where the insulation ends are exposed to containment atmosphere, and sealant use to prevent water leakage to the containment liner.
The proposed examination provides an acceptable level of quality and safety while not presenting an undue challenge to the moisture barrier insulation panels.
5
2.2.6 Staff Evaluation of IWE/IWL-02:
In lieu of performing VT-3 examinations, in accordance with ASME B&PV Code, 1992 Edition, 1992 Addenda, Table IWE-2500-1, Examination Category E-D, on the containment moisture barriers, the licensee proposed to perform a VT-3 examination on those portions of the 228-foot elevation concrete-metal liner moisture barrier that are exposed when a maintenance activity requires removal of the associated barrier insulation.
In its request, the licensee described the schedule when those insulation panels have been and will be removed for inspecting the concrete-metal liner moisture barrier at 228-foot elevation (the only concrete-metal liner moisture barrier used at HBRSEP, Unit 2). During the RO 18, 18 insulation panels at the 228-foot elevation (the lowest row of insulation sheathing panels) were removed and the moisture barrier was removed for the inspection of the containment liner adjacent to the moisture barrier. The inspection found that there was no evidence of corrosion on the liner adjacent to the moisture barrier. The inspection of the remaining portion of liner at concrete-to-containment liner interface will be completed in RO 19 and RO 20. (As described in Relief Request IWE/IWL-01, of approximately 58 panels on the lowest row of sheathing, 18 panels were removed in RO 18, approximately 24 panels are planned to be removed in RO 19, and approximately 16 panels are planned to be removed in RO 20.) Based on the findings during RO 18 and examination plans scheduled for RO 19 and RO 20, the licensee concluded that the proposed alternative (a VT-3 examination of the containment moisture barrier be performed when maintenance activities require removal of the liner insulation) would provide an acceptable level of quality and safety.
Based on the inspection findings that the liner adjacent to the moisture barrier at 228-foot elevation (the only moisture barrier used at HBRSEP, Unit 2) did not show evidence of corrosion, the staff finds that the proposed alternatives in conjunction with the examinations that have been completed during RO 18 and the examinations that will be performed during RO 19 and RO 20 will provide an acceptable level of quality and safety. Therefore, the staff concludes that the relief proposed by the licensee is authorized pursuant to 10 CFR 50.55a(a)(3)(i).
2.3 RELIEF REQUEST IWE/IWL-03 2.3.1 Code Requirements:
ASME B&PV Code, 1992 Edition, 1992 Addenda,Section XI, Table IWE-2500-1, "Examination Categories," Examination Category E-G, requires a visual examination of the surfaces of bolted connections in accordance with the acceptance standard of IWE-3515, "Standards for Examination Category E-G, Pressure Retaining Bolting."
The acceptance standard requires a VT-1 examination of bolting material, in accordance with the material specification, for defects that may cause the bolted connection to violate either the leakage tightness or structural integrity of the containment. Applicable pressure-retaining bolted connections are required to be visually inspected once per 10-year ISI interval. Deferral of the inspections to the end of the interval is permissible when the bolting is not disturbed.
6
2.3.2 Specific Relief Requested:
Relief is requested from the acceptance standard for pressure-retaining bolting specified in ASME B&PV Code, 1992 Edition, 1992 Addenda, Paragraph IWE-3515.1. The alternative standard proposed will be a performance criteria based on conditions that may cause the bolted connection to violate either containment leaktightness or structural integrity. Conditions that cause the bolted connection to violate either containment leaktightness or structural integrity will be corrected by a repair/replacement activity prior to returning the component to service.
This request for relief is applicable to pressure-retaining bolting components classified as Class MC and CC and subject to the requirements of Table IWE-2500- 1, Examination E-G, at HBRSEP, Unit 2.
2.3.3 Alternative Examination(s):
The alternative acceptance standard that will be utilized for examination of pressure-retaining bolting is the performance criteria stated below.
Pressure-retaining bolting shall be examined for conditions that may cause the bolted connection to violate either containment leaktightness or structural integrity. Examples of such conditions are:
1.1 Bent, twisted, fractured, or deformed bolts or studs; 1.2 Fractured bolts, studs or nuts; 1.3 Missing or loose bolts, studs, nuts or washers; and 1.4 Degraded coating on bolting surfaces accompanied by damage or degradation of the bolting material.
Conditions identified during the examination will be evaluated. Conditions that may cause the bolted connection to violate either containment leaktightness or structural integrity will be corrected by a repair/replacement activity prior to returning the component to service.
2.3.4 Basis for Requesting Relief:
In accordance with 10 CFR 50.55a(a)(3)(i), relief is requested for HBRSEP, Unit 2 on the basis that the proposed alternatives will provide an acceptable level of quality and safety.
The alternative acceptance standard will provide a performance-based criteria rather than the VT-1 examination in accordance with the material specification. The performance-based acceptance standard will more appropriately determine indication of functional acceptance or indication of degradation of bolted connection than the required compliance with the material specification. The alternative acceptance standard requires that conditions identified during the examination be evaluated to determine if the conditions would cause the bolting to be unacceptable. The proposed alternative also requires corrective actions (i.e., repair or replacement activity) to be taken when a condition is identified that may cause the bolting to violate either the containment leaktightness or structural integrity. Both of these actions ensure 7
eS identified conditions are properly evaluated and/or corrective actions are taken prior to returning the associated component to service.
2.3.5 Justification for Granting Relief:
Compliance with the ASME B&PV Code requirement for VT-1 examination of bolted connections for compliance with the material specifications is not appropriate. The alternative requirement proposed will provide the appropriate standard for the examination and acceptance of bolting that has been in service. Applying this alternative standard will require the bolting to be examined for defect conditions that may cause the bolted connection to violate either containment leaktightness or structural integrity. Examples of these conditions are also provided in the proposed alternative standard. Therefore, the proposed alternative examinations will provide an acceptable level of quality and safety.
2.3.6 Staff Evaluation of IWE/IWL-03:
In lieu of meeting the requirements of ASME B&PV Code, 1992 Edition, 1992 Addenda,Section XI, Table IWE-2500-1, "Examination Categories," Examination Category E-G, that a visual examination of the surfaces of bolted connections shall be performed in accordance with the acceptance standard of IWE-3515, "Standards for Examination Category E-G, Pressure Retaining Bolting," the licensee proposed to use a performance criterion based on conditions that may cause the bolted connection to violate either containment leaktightness or structural integrity. Conditions that cause the bolted connection to violate either containment leaktightness or structural integrity will be corrected by a repair/replacement activity prior to returning the component to service.
The staff finds that an examination based on the proposed alternative acceptance standard will be more appropriate and provides a reasonable method that will give an indication of functional acceptance or the indication of a degraded bolted connection than the required compliance with the material specification. Application of the alternative method will require the bolting be examined for defect conditions that may cause the bolted connection to violate either containment leaktightness or structural integrity. The staff concludes that the licensee's alternative acceptance standard is authorized on the basis that the proposed alternative provides an acceptable level of safety pursuant to 10 CFR 50.55a(a)(3)(i).
2.4 RELIEF REQUEST IWE/IWL-04 2.4.1 Code Requirements:
ASME B&PV Code, 1992 Edition, 1992 Addenda,Section XI, Table IWE-2500-1, "Examination Categories," Examination Category E-D, requires a visual examination of 100% of the containment seals and gaskets for Class MC pressure-retaining components and metallic shell and penetration liners of Class CC components.
The required examination method for these examinations is a VT-3 examination. One test per 10-year ISI interval is required. Deferral of the test to the end of the interval is not permitted.
8
2.4.2 Specific Relief Requested:
Relief is requested from performing the VT-3 examinations specified in Table IWE-2500-1, Examination Category E-D for containment penetration seals and gaskets. In lieu of performing the VT-3 examinations for containment penetration seals and gaskets, the current program for leakage testing of containment penetrations in accordance with 10 CFR 50, Appendix J, is proposed to provide an acceptable level of quality and safety.
This request for relief is applicable to components classified as Class MC or CC and subject to the requirements of Table IWE-2500-1, Examination Category E-D, at HBRSEP, Unit 2.
2.4.3 Alternative Examination(s):
As an alternative to the requirements of the ASME B&PV Code, 1992 Edition, 1992 Addenda, requirements for VT-3 examination of containment vessel seals and gaskets, the leaktight integrity of seals and gaskets utilized on penetrations (e.g., airlocks, hatches) that are required for containment vessel leaktight integrity shall be verified in accordance with the requirements of 10 CFR 50, Appendix J.
2.4.4 Basis for Requesting Relief:
In accordance with 10 CFR 50.55a(a)(3)(i), relief is requested for HBRSEP, Unit 2 on the basis that the proposed alternative examination would provide an acceptable level of quality and safety.
Containment penetration seals and gaskets must be disassembled and re-assembled during a refueling outage for the purpose of performing the VT-3 examination. The seals and gaskets associated with these penetrations are not accessible for examination when the penetration is assembled. The disassembly and re-assembly activity associated with a VT-3 examination of seals and gaskets introduces the possibility of component damage that would not otherwise occur. These penetrations are periodically tested in accordance with 10 CFR 50, Appendix J to verify leakage is within the requirements of 10 CFR 50, Appendix J. The purpose of the 10 CFR 50, Appendix J test is to detect local leaks at containment peak accident pressure and to measure leakage across the leakage-limiting boundary of containment penetrations whose design incorporates resilient seals, gaskets, sealant compounds, and electrical penetrations fitted with flexible metal seal assemblies. As such, the 10 CFR 50, Appendix J test functionally tests containment penetrations to the required accident conditions. If unacceptable leakage is identified during the test, corrective measures would be taken.
2.4.5 Justification for Granting Relief:
Relief is requested from ASME B&PV Code requirements for visual examination of containment vessel seals and gaskets, and the alternative examinations proposed provide an acceptable level of quality and safety. The required examinations involve disassembly of each penetration for a visual examination. The penetrations are already functionally tested each outage in accordance with 10 CFR 50, Appendix J. The functional testing in accordance with 10 CFR 50, Appendix J provides an acceptable level of quality and safety.
9
2.4.6' Staff Evaluation of IWE/IWL-04:
The licensee proposes to use, in lieu of performing the VT-3 examinations for containment penetration seals and gaskets, the current program for leakage testing containment penetrations in accordance with 10 CFR 50, Appendix J.
In its request, the licensee stated that because the seals and gaskets associated with these penetrations are not accessible for examination when the penetration is assembled, containment penetration seals and gaskets must be disassembled and re-assembled for the purpose of performing the VT-3 visual examination. These activities (disassembly and re assembly of seals and gaskets) associated with a VT-3 visual examination would introduce the possibility of component damage that would not otherwise occur. The periodical test of penetrations in accordance with 10 CFR 50, Appendix J will detect local leakage at containment peak accident pressure and measure leakage across the leakage-limiting boundary of containment penetrations whose design incorporates resilient seals, gaskets, sealant compounds, and electrical penetrations fitted with flexible metal seal assemblies. If unacceptable leakage is identified during the test, corrective measures would be taken.
Also, it is the staffs understanding that the 1993 Addenda to ASME Code,Section XI has recognized that disassembly of joints for the sole purpose of performing 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 the level of quality and safety.
On the basis discussed above, the staff concludes that the alternative proposed by the licensee will provide reasonable assurance of the functionality and integrity of the containment penetration seals and gaskets during the testing required by 10 CFR Part 50, Appendix J. The proposed alternative is authorized pursuant to 10 CFR 50.55afa)(3)(ii) on the basis that compliance with the specific requirements of the Code would result in hardship without a compensating increase in the level of quality and safety.
2.5 RELIEF REQUEST IWE/IWL-05 2.5.1 Code Requirements:
ASME B&PV Code, 1992 Edition, 1992 Addenda,Section XI, Paragraph IWE-2420, "Successive Inspections," items (b) and (c) provide requirements for successive examinations of Class MC and metallic liners of Class CC components when examination results require evaluation of flaws, areas of degradation, or repairs and the component is found to be acceptable for continued service.
Paragraph IWE-2420(b) requires successive examinations for components when examination results require evaluation of flaws, areas of degradation, or repairs in accordance with Paragraph IWE-3000, "Acceptance Standards." Paragraph IWE-2420(c) states that if 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."
10
2.5.2 Specific Relief Requested:
Relief is requested from the provisions of Paragraphs IWE-2420(b) and (c) that require successive examinations of repaired areas in accordance with Table IWE-2500-1, Examination Category E-C. In lieu of the successive examinations required by IWE-2420, an acceptable level of quality and safety will be provided by the repair process and subsequent acceptance examinations and evaluations.
2.5.3 Alternative Examination(s):
Alternative examinations are those inspections and evaluations required by the ASME Code for repairs, as discussed below.
2.5.4 Basis for Requesting Relief:
In accordance with 10 CFR 50.55a(a)(3)(i), relief is requested for HBRSEP, Unit 2 on the basis that the proposed alternative would provide an acceptable level of quality and safety.
The purpose of the repair is to restore the component to an acceptable condition for continued service and to prevent recurrence.
Following the repair, examination is performed in accordance with Paragraph IWA-2200, "Examination Methods." Acceptance of this examination will confirm the absence of the unacceptable condition or reveal that the condition no longer exceeds the established acceptance standards. In both cases, this examination verifies that the repair has restored the component to an acceptable condition, and can be returned to service. Additionally, following a repair, Appendix J testing may be required in accordance with Paragraph IWE-5220, "Tests Following Repair, Modification, or Replacement." Once the repair has been verified as acceptable, successive examinations of the repaired area, in accordance with Examination Category E-C of Table IWE-2500-1, "Examination Categories," are not warranted.
2.5.5 Justification for Granting Relief:
As discussed above, following the repair, examination is performed in accordance with Paragraph IWA-2200, "Examination Methods." Acceptance of this examination will confirm the absence of the unacceptable condition or reveal that the condition no longer exceeds the established acceptance standards. Thus, the proposed alternative provides an acceptable level of quality and safety.
Further, the ASME Main Committee and the Board of Nuclear Codes and Standards have determined that the requirement to perform successive examinations of repaired areas per Examination Category E-C is no longer warranted. Both organizations have approved the revision to Subsection IWE that eliminated this requirement. This revision of Subsection IWE was published in the ASME B&PV Code, 1998 Edition,Section XI.
11
2.5.6 Staff Evaluation of IWE/IWL-05:
As an alternative to the requirements of IWE-2420(b) and (c) that require successive examinations of repaired areas in accordance with Table IWE-2500-1, the licensee proposes to use the process and acceptance examinations and evaluations required by the Code for repairs.
The staff finds that when repairs are complete, IWA-4150 requires licensees to evaluate the suitability of the repair. When a repair is required because of failure of an item, the evaluation shall consider the cause of failure to ensure that the repair is suitable. Considering that the failure mechanism is identified and corrected as required and the repair receives preservice examinations, as required, the proposed alternative will provide reasonable assurance of structural integrity. In doing this, the requirements of successive examinations are deemed to be unnecessary. Furthermore, IWB-2420(b), IWC-2420(b), and IWD-2420(b) do not require the successive inspection of repairs for ASME Code Class 1, 2, and 3 components as required in IWE-2420(b) for ASME Code Class MC components. On this basis, the licensee's proposed alternative is authorized pursuant to 10 CFR 50.55a(a)(3)(ii) that compliance with the specific Code requirements would result in hardship without a compensating increase in the level of quality and safety.
2.6 RELIEF REQUEST IWE/IWL-06 2.6.1 Code Requirements:
ASME B&PV Code, 1992 Edition, 1992 Addenda,Section XI, Table IWE-2500-1, "Examination Categories," Examination Category E-G, "Pressure Retaining Bolting," requires a 100% VT-1 examination of the surfaces of pressure-retaining bolted connections in Class MC, and in the metallic liners of Class CC components.
2.6.2 Specific Relief Requested:
Relief is requested from performing the VT-1 visual examination of the pressure-retaining bolting subject to examination in accordance with Table IWE-2500-1, "Examination Categories,"
Examination Category E-G, "Pressure Retaining Bolting." It is proposed that a general visual inspection of the bolted connections will be performed with subsequent actions as described below.
2.6.3 Alternative Examination(s):
As an alternative inspection, it is proposed that a general visual examination in accordance with IWE 3510.1, 'Visual Examinations - General," of each pressure-retaining bolted connection will be performed once per inspection interval. The bolted connection will be examined in its "as found" condition and will not be disassembled for the inspection if disassembly is not otherwise required. If an area is determined to be suspect during the general visual examination, a detailed visual examination will be performed of the suspect area to determine the magnitude and extent of the suspect area. If deemed necessary, the bolted connection will be disassembled to support the performance of the detailed visual examination.
12
2.6.4 Basis for Requesting Relief:
In accordance with 10 CFR 50.55a(a)(3)(i), relief is requested for HBRSEP, Unit 2 on the basis that the proposed alternative would provide an acceptable level of quality and safety.
The bolted connections associated with containment are also subject to testing in accordance with 10 CFR 50, Appendix J, "Primary Reactor Containment Leakage Testing for Water-Cooled Power Reactors." Appendix J requires that each of these bolted connections be tested on a routine basis. The purpose of the Appendix J test is to verify the leaktight integrity of the containment structure. Thus, the visual examination only needs to be performed to evaluate any inservice effects that could adversely impact the performance of the bolted connections that have been adequately assembled and tested. A general visual examination of each pressure retaining bolted connection, including its bolts, studs, nuts, washers, etc. will be performed once each inspection interval to detect degradation. If an area is determined to be suspect, a more detailed visual examination to determine the magnitude and extent of the suspect areas will be performed.
2.6.5 Justification for Granting Relief:
The bolted connections associated with containment are subject to testing in accordance with 10 CFR 50, Appendix J. The purpose of Appendix J testing is to verify the leaktight integrity of the containment structure. Thus, the general visual examination only needs to be performed to evaluate any inservice effects that could adversely impact the performance of the bolted connections and will provide an acceptable level of quality and safety.
Further, the ASME Main Committee and the Board of Nuclear Codes and Standards have approved a revision to Subsection IWE to eliminate the requirement for a VT-1 examination of pressure-retaining bolting. This revision of Subsection IWE was published in the ASME B&PV Code, 1998 Edition, Section Xl.
2.6.6 Staff Evaluation of IWE/IWL-06:
In lieu of performing the VT-1 visual examination of the pressure-retaining bolting subject to examination in accordance with Table IWE-2500-1, "Examination Categories," Examination Category E-G, "Pressure Retaining Bolting," the licensee proposed to perform a general visual examination in accordance with IWE 3510.1, 'Visual Examinations - General," of each pressure retaining bolted connection once per inspection interval. During the examination, the bolted connection will be examined in its "as-found" condition and will not be disassembled for the inspection if disassembly is not otherwise required. The basis for the licensee's proposal is that the bolted connections associated with containment are subject to testing in accordance with 10 CFR 50, Appendix J to ensure the leaktight integrity of the containment structure. The general visual examination is applied to evaluate any inservice effects that could adversely impact the performance of the bolted connections and will provide an acceptable level of quality and safety.
The staff finds that in addressing the 10 CFR 50, Appendix J requirements together with the general visual examination (in lieu of performing the VT-1 visual examination of the pressure 13
retaining bolting subject to examination in accordance with Table IWE-2500-1, "Examination Categories," Examination Category E-G, "Pressure Retaining Bolting") for evaluating inservice effects that could adversely impact the performance of the bolted connections will ensure the leak-tight integrity of the containment structure with bolted connections. The staff concludes that the alternative proposed by the licensee is authorized on the basis that it provides an acceptable level of quality and safety pursuant to 10 CFR 50.55a(a)(3)(i).
2.7 RELIEF REQUEST IWE/lWL-07 2.7.1 Code Requirements:
ASME B&PV Code, 1992 Edition, 1992 Addenda,Section XI, Table IWE-2500-1, "Examination Categories," Examination Category E-G, "Pressure Retaining Bolting," provides requirements for a torque or tension test of bolted connections that have not been disassembled and reassembled during the inspection interval.
2.7.2 Specific Relief Requested:
Relief is requested from performing the torque or tension test in accordance with Table IWE-2500-1, "Examination Categories," Examination Category E-G, "Pressure Retaining Bolting," for bolted connections that have not been disassembled and reassembled during the inspection interval.
2.7.3 Alternative Examination(s):
The leaktight integrity of bolted connections that are required for containment vessel leaktight integrity will be verified in accordance with the applicable requirements of 10 CFR 50, Appendix J, "Primary Reactor Containment Leakage Testing for Water-Cooled Power Reactors."
2.7.4 Basis for Requesting Relief:
In accordance with 10 CFR 50.55a(a)(3)(ii), relief is requested for HBRSEP, Unit 2 on the basis that compliance with the specified requirements would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety. Compliance with ASME Code requirements are considered a hardship or an unusual difficulty because the torque or tension test is only required for those bolted connections that are not disassembled and reassembled during the inspection interval. To accomplish this test, HBRSEP, Unit 2 would be required to de-torque, re-torque or retension, and test the bolted connection per 10 CFR 50, Appendix J. These tasks would be required for the sole purpose of performing this test. Since the integrity of the bolted connections is verified by 10 CFR 50, Appendix J testing, the cost and personnel radiation exposure associated with this task constitutes a hardship or an unusual difficulty without a compensating increase in quality and safety.
14
2.7.5 Justification for Granting Relief:
Compliance with ASME Code torque/tension test requirements for bolted connections that have not been disassembled and reassembled during the inspection interval is a hardship or unusual difficulty without a compensating benefit in quality or safety.
The bolted connections, subject to the torque or tension test, are those that are required for containment leaktight integrity. As required by 10 CFR 50, Appendix J, these same bolted connections are required to be leak rate tested by a local leak rate test. The purpose of the test is to detect local leaks at containment design pressure by measuring leakage across the leakage-limiting boundary of containment mechanical penetrations containing resilient seals, gaskets, and sealant compounds, and containment electrical penetrations fitted with flexible metal seal assemblies and associated bolted connections, as applicable. If excessive leakage is identified during the test, corrective measures would be taken and the connection re-tested in accordance with written procedures.
Further, the ASME Main Committee and the Board of Nuclear Codes and Standards have approved a revision of Subsection IWE that eliminated this requirement. This revision of Subsection IWE was published in the 1998 Edition of the ASME Section XI Code.
2.7.6 Staff Evaluation of IWE/IWL-07:
ASME Section XI, 1992 Edition with the 1992 Addenda, Table IWE-2500-1, Examination Category E-G, Pressure Retaining Bolting, Item E8.20 requires bolt torque or tension testing on bolted connections that have not been disassembled and reassembled during the inspection interval. This examination is used to aid in the determination that leaktight seals exist and that the structural integrity of the subject bolted connections is maintained. The licensee proposed to use the 10 CFR 50, Appendix J test as an alternative to the Code requirement for verifying the leaktight integrity of bolted connections that are required for containment vessel leaktight integrity.
The staff finds that compliance with ASME Code requirements will cause a hardship or an unusual difficulty because untorquing and subsequent re-torquing bolted connections which are verified to have acceptable leakage through 10 CFR 50, Appendix J testing do not provide an increase in the level of quality and safety. The staff also finds that the alternative approach proposed by the licensee (the test required by 10 CFR 50, Appendix J to verify the leaktight integrity of bolted connections for containment vessel leaktight integrity) will provide a reasonable assurance of the containment leaktight integrity. On this basis, the staff concludes that the alternative proposed by the licensee is authorized pursuant to 10 CFR 50.55a(a)(3)(ii).
2.8 RELIEF REQUEST IWE/IWL-08 2.8.1 Code Requirements:
ASME B&PV Code, 1992 Edition, 1992 Addenda,Section XI, Table IWE-2500-1, "Examination Categories," Examination Category E-A requires a 100% VT-3 examination of accessible surface areas of the containment vessel.
15
The required examination method for these examinations is a VT-3 examination. One examination per 10-year ISI interval is required at the end of the inspection interval.
2.8.2 Specific Relief Requested:
Relief is requested from performing the VT-3 examination of the accessible surface areas of the containment and to perform general visual and detailed examinations as an alternative examination.
This request for relief is applicable to components classified as Class MC or CC and subject to the requirements of Table IWE-2500-1, Examination Category E-A, at HBRSEP, Unit 2.
2.8.3 Alternative Examination(s):
As an alternative to the ASME B&PV Code, 1992 Edition with 1992 Addenda requirements for a VT-3 examination, a general visual examination in accordance with paragraph IWE-3510.1 of the accessible surface areas of the containment will be performed. When evidence of degradation is detected, a detailed visual examination will be performed of the suspect area. If a detailed visual examination cannot be performed, the suspect area will be evaluated and approved by a registered professional engineer (RPE). The general and/or detailed visual examination will be performed by personnel certified in accordance with ANSI N45.2.6.
2Property "ANSI code" (as page type) with input value "ANSI N45.2.6.</br></br>2" contains invalid characters or is incomplete and therefore can cause unexpected results during a query or annotation process..8.4 Basis for Requesting Relief:
In accordance with 10 CFR 50.55a(a)(3)(i), relief is requested for HBRSEP, Unit 2 from compliance with the ASME B&PV Code requirements on the basis that the proposed alternatives will provide an acceptable level of quality and safety.
The VT-3 requirements were developed for detecting flaws in metal components, and are more stringent than those that would be required for the detection of degradation of containment surface area due to corrosion. Corrosion of the base metal is the primary issue of concern for the containment surface areas, and control will be established for the performance of a general visual examination to detect age-related mechanisms that may affect the structural integrity and/or leaktightness of the containment. The alternative examination proposed is a general visual examination performed of accessible surface areas by examiners qualified as stated below. If an area is determined to be suspect during the general visual examination, additional actions will be taken.
The general visual examination will be performed in accordance with paragraph IWE-3510.1.
When evidence of degradation is detected by the examiner, a detailed visual examination will be performed to determine the magnitude and extent of any deterioration and distress of suspect containment surfaces. If a detailed visual examination cannot be performed, the acceptability of the suspect area will be evaluated. The evaluation will address the requirements outlined in 10 CFR 50.55a(b)(2)(x)(A).
The general and/or detailed visual examination will be performed by personnel certified in accordance with ANSI N45.2.6. This level of certification will verify that the capability and visual 16
acuity'of the examiners are sufficient to detect evidence of potential degradation of the containment's accessible surface areas.
2.8.5 Justification for Granting Relief:
Relief is requested from ASME B&PV Code requirements for VT-3 examination of accessible surface areas. The proposed alternative to perform general and detailed visual examinations is sufficient to identify the principle degradation of accessible containment surface areas. The alternative qualification requirements for examiners assure an equivalent level of training and qualification. Therefore, the proposed alternatives provide an acceptable level of quality and safety.
2.8.6 Staff Evaluation of IWE/IWL-08:
The licensee requested relief from performing the VT-3 examination of the accessible surface areas of the containment and to perform general visual and detailed examinations as an alternative examination. The proposed alternative requires the licensee to perform a general visual examination in accordance with paragraph IWE-3510.1 of the accessible surface areas of the containment. When evidence of degradation is detected, a detailed visual examination will be performed to determine the magnitude and extent of any distress and deterioration and distress of suspect containment surfaces.
The staff finds that the proposed alternative to perform general and detailed visual examinations for the containment liner surface areas with no insulation is adequate to identify degradation of accessible containment surface areas, and the alternative qualification requirements for examiners assure an acceptable level of training and qualification. Therefore, the staff concludes that the alternative proposed by the licensee is authorized pursuant to 10 CFR 50.55a(a)(3)(i) on the basis that the proposed alternative provides an acceptable level of quality and safety.
2.9 RELIEF REQUEST IWE/IWL-09 2.9.1 Code Requirements:
ASME B&PV Code, 1992 Edition, 1992 Addenda,Section XI, Table IWL-2500-1, "Examination Categories," Examination Category L-A, requires visual examinations of concrete surfaces of the concrete containment in accordance with the requirements of Paragraph IWL-2510.
The required examination method for these areas is a VT-3C examination. Suspect areas receive a VT-1C examination. Paragraph IWL-2510 specifies detailed requirements for visual examination methods of concrete.
2.9.2 Specific Relief Requested:
Relief is requested from performing the VT-3C examination and a VT-1 C examination of suspect areas, and to perform a general visual and detailed visual examinations of suspect areas as an alternative examination.
17 I
This request for relief is applicable to components classified as Class CC and subject to the requirements of Table IWL-2500-1, Examination Category L-A, at HBRSEP, Unit 2.
2.9.3 Alternative Examination(s):
As an alternative to the ASME B&PV Code, 1992 Edition with 1992 Addenda requirements for a VT-1C and VT-3C examination, a general visual examination of the concrete surfaces of the containment will be performed. When evidence of degradation is detected, a detailed visual examination will be performed of the suspect area. If a detailed visual examination cannot be performed, the suspect area will be evaluated and approved by an RPE. The general and/or detailed visual examination will be performed by personnel certified in accordance with ANSI N45.2.6.
2Property "ANSI code" (as page type) with input value "ANSI N45.2.6.</br></br>2" contains invalid characters or is incomplete and therefore can cause unexpected results during a query or annotation process..9.4 Basis for Requesting Relief:
In accordance with 10 CFR 50.55a(a)(3)(ii), relief is requested for HBRSEP, Unit 2 on the basis that compliance with the ASME B&PV Code requirements would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety.
Concrete deterioration and distress can be effectively identified by the performance of a general visual examination. The alternative examination will be a general visual examination performed on surface areas by examiners qualified as stated below. If an area is determined to be suspect during the general visual examination, a detailed visual examination will be performed of the suspect area and compared to established acceptance criteria so that the magnitude and extent of deterioration and/or distress is properly characterized for evaluation. The procedure governing the general and detailed visual examination methods will be reviewed and approved by an RPE. If a detailed visual examination cannot be performed, the acceptability of the suspect area will be evaluated. The evaluation will address the requirements outlined in 10 CFR 50.55a(b)(2)(ix)(E).
The general and/or detailed visual examination will be performed by personnel certified in accordance with ANSI N45.2.6. This level of certification will verify that the capability and visual acuity of the examiners are sufficient to detect evidence of potential degradation of the concrete structure. Prior to performing the examinations, the examiners will also be required to successfully complete training (i.e.,.training developed by the Electric Power Research Institute (EPRI), or equivalent) on the proper techniques for examining components and items subject to the requirements of Subsection IWL.
2.9.5 Justification for Granting Relief:
Compliance with ASME B&PV Code requirements for VT-1C and VT-3C examinations of containment concrete surface areas impose an additional burden with no compensating benefit in quality or safety. Relief is requested from VT-1C and VT-3C examinations of concrete surface areas. The proposed alternative to perform general and detailed visual examinations is sufficient to identify degradation of containment concrete surface areas. The alternative qualification requirements for examiners assure an equivalent level of training and qualification.
Therefore, the proposed alternatives provide an acceptable level of quality and safety.
18
FuTrther, the ASME Main Committee and the Board of Nuclear Codes and Standards have determined that the requirement to perform VT-1C and VT-3C examinations of concrete surface areas is no longer warranted. Both organizations have approved the revision to Subsection IWL that revised this requirement to a general visual examination. This revision of Subsection IWL was published in the ASME B&PV Code, 1998 Edition,Section XI.
2.9.6 Staff Evaluation of IWE/IWL-09:
The licensee requested relief from performing the VT-3C examination and a VT-1 C examination of the suspect areas. The proposed alternative requires the licensee to perform a general visual examination of concrete surface areas of the containment. When evidence of degradation is detected, a detailed visual examination will be performed of suspect containment surfaces.
The staff finds that the proposed alternative to perform general and detailed visual examinations is adequate to identify degradation of containment surface areas and the alternative qualification requirements for examiners assure an acceptable level of training and qualification. The staff concludes that the alternative proposed by the licensee is authorized on the basis that it provides an acceptable level of quality and safety pursuant to 10 CFR 50.55a(a)(3)(i).
3.0 CONCLUSION
S Based on our review of the information provided in the requests for relief (Relief Requests IWE/IWL-01 through IWE/IWL-09), the staff concludes that for Relief Requests IWE/IWL-01, 02, 03, 06, 08 and 09, the licensee's proposed alternatives will provide an acceptable level of quality and safety. Therefore, the proposed alternatives are authorized pursuant to 10 CFR 50.55a(a)(3)(i). For Relief Requests IWE/IWL-04, 05 and 07, the staff concludes that compliance with the Code requirements would result in a burden without a compensating increase in the level of quality and safety, and that licensee's proposed alternatives will provide reasonable assurance of containment pressure integrity. Therefore, these proposed alternatives are authorized pursuant to 10 CFR 50.55a(a)(3)(ii).
Principal Contributor: T. Cheng, NRRIEMEB Date: July 26, 1999 19
.4.Q' REFERENCES (1)
Letter from R. L. Warden (Carolina Power and Light Company) to NRC, "Request for Relief from ASME Boiler and Pressure Vessel Code,Section XI, Subsections IWE and IWL Requirements for Containment Inspections, H. B. Robinson Steam Electric Plant, Unit No. 2," dated January 20, 1999.
(2)
Letter from R. L. Warden (Carolina Power and Light Company) to NRC, "Revised Relief Requests - Containment Liner and Moisture Barrier, H. B. Robinson Steam Electric Plant, Unit No. 2," dated June 25, 1999.
20
Summary of Relief Requests H. B. Robinson Steam Electric Plant, Unit 2 Relief 10 CFR 50.55a -
Recommended Request No.
ASME Code Issue Identification NRC Action Remarks IWE/IWL Section IWE/IWL-01 Table IWE-2500-1 E-A Visual Examination of Insulated authorized Containment Liner (a)(3)(i)
IWE/IWL-02 Table IWE-2500-1 E-D Visual Examination of Moisture (a)(3)(i) authorized Barriers IWE/IWL-03 IWE-3515.1 Acceptance Standard for Pressure authorized Retaining Bolting (a)(3)(i)
IWE/IWL-04 Table IWE-2500-1 E-D Visual Examination of Seals and (a)(3)(ii) authorized Gaskets IWE/IWL-05 IWE-2420(b) and (c)
Successive Examination Following authorized a Repair (a)(3)(ii)
IWE/IWL-06 Table IWE-2500-1 E-G Visual Examination of Pressure authorized Retaining Bolting (a)(3)(i)
IWE/IWL-07 Table IWE-2500-1 E-G Torque/Tension Test of Pressure authorized Retaining Bolting (a)(3)(ii)
IWE/IWL-08 Table IWE-2500-1 E-A Visual Examination of Accessible Surface Areas of Containment (a)(3)(i) authorized Vessel IWE/IWL-09 Table IWE-2500-1 L-A Visual Examination of Accessible authorized and IWL-2510 Concrete Surface Areas (a)(3)(i) 21
~.-2 Further details regarding the staff's evaluation and conclusions are contained in the enclosed Safety Evaluation.
Sincerely, original signed by:
Herbert N. Berkow, Director Project Directorate II Division of Licensing Project Management Office of Nuclear Reactor Regulation Docket No. 50-261
Enclosure:
Safety Evaluation cc w/encl: See next page DISTRIBUTION:
Docket File RScholl (RFS) SE only TCheng, NRR, EMEB PUBLIC BBonser, Region II DTerao, MCEB, NRR RSubbaratnam HBerkow CJozwiak, DLPM, NRR PDII Reading File ACRS OGC
- See P{revious concurrence DOCUMENT NAME:G:\\PDIl-2\\Robinson\\M4637rlf.wpd
- SE Dated July 12, 1999 To receive a copy of this document, indicate in the box: "C" = Copy without enclosures "E" = Copy with enclosures "N" = No copy OFFICE PDIIS2:PM PDIIS2:LAI OGC**
EMEB*
PDI NAME Ram Subbaratnam** EDunnington** RBachmann TCheng H e W
DATE 7/14/99 7/14/99 7/ 20 /99 7/12/99 7/ ; /99 OFFICIAL RECORD COPY