SVP-02-059, Request for Scheduler Exemption for Performance of Reactor Pressure Vessel Nozzle-to-Vessel Weld & Nozzle Inside Radius Section Examinations Required by 10CFR 50.55a
| ML022040476 | |
| Person / Time | |
|---|---|
| Site: | Quad Cities  |
| Issue date: | 07/10/2002 |
| From: | Tulon T Exelon Generation Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| SVP-02-059 | |
| Download: ML022040476 (6) | |
Text
Exelon.
Exelon Generation Company, LLC www.exeloncorp.com Nuclear Ouad Cities Nuclear Power Station 22710 206' Avenue North Cordova, IL 61242- 9740 SVP-02-059 July 10, 2002 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555 Quad Cities Nuclear Power Station Unit 1 Facility Operating License No. DPR-29 NRC Docket No. 50-265
Subject:
Request for Scheduler Exemption for Performance of Reactor Pressure Vessel Nozzle-to-Vessel Weld and Nozzle Inside Radius Section Examinations Required by 10 CFR 50.55a In accordance with 10 CFR 50.12, 'Specific exemptions', Exelon Generation Company (EGC),
LLC, is requesting a schedular exemption from the requirements of 10 CFR 50.55a, 'Codes and standards', paragraph (g)(4)(ii) concerning inservice examination of Reactor Pressure Vessel Nozzle-to-Vessel Welds and Nozzle Inside Radius Sections for the Quad Cities Nuclear Power Station Unit 1.
This schedular exemption requests an extension for the performance of the third 120-month inspection interval November 2002 (Q1R17) examinations, as listed in Attachment A of this letter, until next scheduled refueling outage, January 2005 (QIR18), which is the first inspection period of the fourth 120-month inspection interval.
The alternative will provide an acceptable level of quality and safety and is requested because the current requirement presents a hardship without a compensating increase in the level of quality and safety.
In summary, we are requesting a one-cycle extension of the requirement to inspect the Reactor Pressure Vessel Nozzle-to-Vessel Welds and Nozzle Inside Radius Sections for the Quad Cities Nuclear Power Station Unit 1 for a complete and thorough inspection, without imposing unnecessary radiation dose accumulation penalties. Quad Cities Nuclear Power Station is requesting your review and concurrence by November 1, 2002.
SVP-02-059 U.S. Nuclear Regulatory Commission Page 2 of 2 Should you have any questions regarding this letter, please contact Mr. Wally Beck at (309) 227-2800.
Respectfully Si'e *thyJ. Tulon Vice President Quad Cities Nuclear Power Station cc: Regional Administrator-NRC Region III NRC Senior Resident Inspector, Quad Cities Nuclear Power Station
ATTACHMENT A QUAD CITIES NUCLEAR POWER STATION UNIT 1 JUSTIFICATION FOR SCHEDULAR EXEMPTION (Page 1 of 4)
EXEMPTION Exelon Generation Company, LLC requests a schedular exemption for Quad Cities Nuclear Power Station (QCNPS) Unit 1 from implementation of inservice examinations of the Reactor Pressure Vessel (RPV)
Nozzle-to-Vessel Welds and Nozzle Inside Radius Sections, per American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel (B&PV) Code Section XI, Table IWB-2500, Examination Category B-D, Item Nos. B3.90 and B3. 100, by the end of the current 120-month inspection interval, as required by 10 CFR 50.55a, 'Codes and standards', paragraph (g)(4)(ii).
The current (third) 120-month inspection interval ends on February 17, 2003 for QCNPS Unit 1. The final refuel outage of the current (third) 120-month inspection interval is November 2002 (QLR17) and the next scheduled refuel outage in January 2005 (Q1R18) is the first inspection period of the fourth 120-month inspection interval.
This schedular exemption requests an extension for the performance of the third 120-month inspection interval November 2002 (Q1R17) examinations of the below listed components until the fourth 120-month inspection interval January 2005 (QiR18). These exams will be credited to the third 120-month inspection interval and will be repeated during the fourth 120-month interval in accordance with the Quad Cities fourth 10-Year Interval ISI Program Plan.
Quad Cities Nuclear Power Station Unit 1 RPV Nozzle-to-Vessel Welds and Nozzle Inside Radius Sections, Category B-D EXAM COMPONENT NUMBER COMPONENT SYSTEM ITEM NUMBER LAST EXAM RESULTS N 1A-IRS' Recirculation Outlet B3.100 05-16-1994 Acceptable NIB-NOZ & NIB-IRS Recirculation Outlet B3.90 & B3.100 10-18-1989 Acceptable N2F-NOZ & N2F-IRS Recirculation Inlet B3.90 & B3. 100 10-20-1989 Acceptable N2G-NOZ & N2G-IRS Recirculation Inlet B3.90 & B3.100 10-19-1992 Acceptable N2H-NOZ & N2H-IRS Recirculation Inlet B3.90 & B3. 100 10-19-1992 Acceptable N2J-NOZ & N2J-IRS Recirculation Inlet B3.90 & B3. 100 10-19-1992 Acceptable N2K-NOZ & N2K-IRS Recirculation Inlet B3.90 & B3. 100 10-19-1992 Acceptable N8B-NOZ & N8B-IRS Jet Pump Instrumentation B3.90 & B3.100 10-27-1992 Acceptable N10-NOZ 2 Stand-By Liquid Control B3.90 10-23-1989 Acceptable Note 1 N1A-NOZ (Recirculation Outlet) Nozzle-to-Vessel Weld, Item Number B3.90, was examined during an earlier outage (QIR13) of the current 120-month inspection interval. CR-32 (TAC NOS. MA7164 and MA7165) stated N 1A IRS would be examined later in the (3rd) Interval to obtain increased coverage. This exemption request would move this examination into the 4 1h 120-month interval.
Note 2 N 10-IRS (Stand-By Liquid Control) Nozzle Inside Radius Section, Item Number B3. 100, is exempt from examination due to the design of the Inside Radius Section, see Relief Request Number CR-01.
ATTACHMENT A QUAD CITIES NUCLEAR POWER STATION UNIT 1 JUSTIFICATION FOR SCHEDULAR EXEMPTION (Page 2 of 4)
DISCUSSION Quad Cities Nuclear Power Station Unit 1 obtained Construction Permit CPPR-23, February 15, 1967.
The vessel, piping systems and associated components were designed and fabricated before the examination requirements of ASME Section XI were formalized and published. This plant was not specifically designed or constructed to permit easy access to the RPV Nozzle-to-Vessel Welds and Nozzle Inside Radius Sections for inservice inspection, from the inside or outside surface.
Physical obstructions imposed by design and construction are typical of vessel appurtenances, sacrificial shield, lead bricks, insulation support rings and structural/component support members. The sacrificial (biological) shield, lead bricks and insulation around the nozzles do not permit ready access by personnel for the inservice examination (ultrasonics) from the outside surface. The inside surface is totally inaccessible, due to the inherent design of a GE BWR-3 reactor vessel.
The preparations required for in-service examination from the outside surface includes scaffold erection/removal, insulation removal/replacement, lead brick removal/replacement and other activities.
The task to access a nozzle for in-service examination employs several work groups and a significant number of man-hours with the attendant large radiation exposure accumulation.
The examination of these components with the current condition of Unit 1 radiation levels constitutes the current hardship. The estimated radioactive dose avoided for exempting these nine nozzles until the following interval will represent savings of a minimum of 60 person-rem.
Plans to mitigate the radiation exposure accumulation by means of chemical decontamination of the Reactor Recirculation System piping were evaluated for the November 2002 (Q1R17) outage. However, several potentially significant detrimental side effects were identified which supports postponing chemical decontamination at this time. Chemical decontamination would result in the removal of the Noble Metals Chemical Application (NMCA) coating on the Reactor Recirculation System piping. Re-application of NMCA to the Reactor Recirculation system piping during, or just after, November 2002 (Q1R17) is not desirable due to the potential effects of double exposure of fuel to the NMCA process. Without a planned reapplication of NMCA until the January 2005 (Q1R 18) refueling outage, the affected piping would have an increased vulnerability to Intergranular Stress Corrosion Cracking (IGSCC) and potential crack creation/growth in the affected piping. This growth would necessitate additional repair activities which must be performed in a high radiation field.
Current industry data and recent fuel failure events along with fuel vendor recommendations, suggest the need to further analyze the use "double application."
Given these two potentially deleterious effects, the optimum time for source term reduction would be during January 2005 (Q1R18) concurrent with the next application of NMCA and permitting inspection activities to be performed in a lower dose environment.
ATTACHMENT A QUAD CITIES NUCLEAR POWER STATION UNIT 1 JUSTIFICATION FOR SCHEDULAR EXEMPTION (Page 3 of 4)
Implementation of inspection requirements for RPV Nozzle-to-Vessel Welds and Nozzle Inside Radius Sections in Class 1 systems, to date, have not resulted in any inspection findings in any of the identified nozzles with the exception of BWR Feedwater and CRD nozzles (NUREG 0619). Approximately 30 years of operational experience show no incidents of cracking in any of the identified through the industry. Additionally, all nine nozzles have received a minimum of three ultrasonic examinations in previous outages and each has received a preservice (baseline) examination along with two previous inservice examinations, first 120-month and second 120-month inspection intervals.
Given that both plant and industry experience shows no evidence of service-induced flaws, the increased risk of extending the inspection interval is minimal. Therefore, an extension of the completion date from the third 120-month inspection interval November 2002 (Q1R17) until the fourth 120-month inspection interval January 2005 (Q1R18), to achieve the inservice examinations due to the hardship of excessive radiation dose is beneficial.
BASIS FOR EXEMPTION As discussed in the following paragraphs, the requested schedular exemption meets the necessary criteria of 10 CFR 50.12, 'Specific Exemptions.'
A. Criteria for granting exemptions are met in accordance with 10 CFR 50.12(a)(1):
- 1. The requested exemptions and the activities which would be allowed thereunder, are authorized by law:
If the criteria established in 10 CFR 50.12(a) are satisfied, as they are in this case, and if no other prohibition exists to preclude the activities which would be authorized by requested exemption, and there is no such prohibition, the commission is authorized by law to grant this exemption request.
- 2. The requested exemption will not present undue risk to the public:
The purpose of performing the RPV Nozzle-to-Vessel Welds and Nozzle Inside Radius Sections inservice examinations is to ensure the structural integrity of the reactor pressure vessel and its appurtenances. The requested exemption is schedular in nature and will result in a complete and thorough inspection. Industry inspections to date have not identified service-induced flaws in the RPV Nozzle-to-Vessel Welds and Nozzle Inside Radius Sections of interest here.
- 3. The requested exemption will not endanger the common defense and security:
The common defense and security are not in any way compromised by this exemption.
ATTACHMENT A QUAD CITIES NUCLEAR POWER STATION UNIT 1 JUSTIFICATION FOR SCHEDULAR EXEMPTION (Page 4 of 4)
B. At least one of the special circumstances is present in accordance with 10 CFR 50.12(a)(2):
- 1. The requested exemption will avoid undue hardship or costs:
The requested schedular exemption is required to prevent unnecessary radiation worker exposure.
Preparations for dose reduction tasks are being pursued for the fourth 120-month inspection interval January 2005 (Q1R 18). Because the requested exemption does not jeopardize the health and safety of the public, as previously discussed, its approval is warranted.
- 2. The requested exemption will only provide temporary relief from the applicable regulation:
The requested exemption is needed for a maximum of 26 months.
APPLICABLE TIME PERIOD This schedular exemption is requested for the third 10-year interval of the Inservice Inspection Program of Quad Cities Nuclear Power Station Unit 1 to be extended to January 2005.