ML080880284
| ML080880284 | |
| Person / Time | |
|---|---|
| Site: | Duane Arnold  |
| Issue date: | 05/01/2008 |
| From: | Lois James NRC/NRR/ADRO/DORL/LPLIII-1 |
| To: | Richard Anderson Florida Power & Light Co |
| James Lois M., NRR/DIPM/IIPB 415-1112 | |
| References | |
| TAC MD5670 | |
| Download: ML080880284 (9) | |
Text
May 1, 2008 Mr. Richard L. Anderson Vice President Duane Arnold Energy Center 3277 DAEC Road Palo, IA 52324-9785
SUBJECT:
DUANE ARNOLD ENERGY CENTER - SAFETY EVALUATION FOR REQUEST FOR RELIEF FROM IWE-2500 REQUIREMENTS FOR VT-3 EXAMINATIONS OF DRYWELL STABILIZERS X-58C AND X-58G FOR THE FIRST 10-YEAR INTERVAL OF THE CONTAINMENT INSPECTION PROGRAM (TAC NO. MD5670)
Dear Mr. Anderson:
In a letter to the Nuclear Regulatory Commission (NRC) dated May 15, 2007, Agencywide Documents Access and Management System (ADAMS) Accession No. ML071430227, as supplemented by a letter dated October 31, 2007, ADAMS Accession No. ML073090068, you requested relief from the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (the Code),Section XI (1992 Edition, 1992 Addenda), Subarticle IWE-2500 requirement to perform the VT-3 visual examinations for the reinforcing structure and integral attachment of Drywell Stabilizers X-58C and X-58G for the first 10-Year interval of the Containment Inspection Program for the Duane Arnold Energy Center (DAEC), which will end on May 21, 2008.
Based on the information provided in the relief request and the responses to the NRC staffs request for additional information, the NRC staff concludes that compliance with the Code requirement would result in hardship without a compensating increase in the level of quality and safety, and the licensees proposed alternative provides reasonable assurance of structural and leak-tight integrity of the affected components. Therefore, the requested relief is authorized in accordance with 10 CFR 50.55a(a)(3)(ii) for the first Containment Inspection Program interval at DAEC.
If you have any questions regarding this matter, please contact Karl Feintuch at (301) 415-3079.
Sincerely,
/RA/
Lois James, Chief Plant Licensing Branch III-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-331
Enclosure:
Safety Evaluation cc w/encl: See next page
ML073090068, you requested relief from the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (the Code),Section XI (1992 Edition, 1992 Addenda), Subarticle IWE-2500 requirement to perform the VT-3 visual examinations for the reinforcing structure and integral attachment of Drywell Stabilizers X-58C and X-58G for the first 10-Year interval of the Containment Inspection Program for the Duane Arnold Energy Center (DAEC), which will end on May 21, 2008.
Based on the information provided in the relief request and the responses to the NRC staffs request for additional information, the NRC staff concludes that compliance with the Code requirement would result in hardship without a compensating increase in the level of quality and safety, and the licensees proposed alternative provides reasonable assurance of structural and leak-tight integrity of the affected components. Therefore, the requested relief is authorized in accordance with 10 CFR 50.55a(a)(3)(ii) for the first Containment Inspection Program interval at DAEC.
If you have any questions regarding this matter, please contact Karl Feintuch at (301) 415-3079.
Sincerely,
/RA/
Lois James, Chief Plant Licensing Branch III-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-331
Enclosure:
Safety Evaluation cc w/encl: See next page DISTRIBUTION:
PUBLIC LPL3-1 r/f RidsNrrDorlLpl3-1 RidsNrrPMKFeintuch RidsNrrLATHarris RidsOgcRp RidsAcrsAcnw&mMailCenter JAdams, EDO RIII RidsRgn3MailCenter RidsNrrDorlDpr GThomas, NRR HAshar, NRR RidsNrrOd RidsNrrAdes ADAMS ACCESSION NUMBER: ML080880284
- Nlo w/changes OFFICE NRR/LPL3-1/PM NRR/LPL3-1/LA NRR/EMCB/BC OGC NRR/LPL3-1/BC NAME KFeintuch THarris KManoly PMoulding*
LJames DATE 4/18/08 4/15/08 3/31/08 4/10/08 5/01/08
Duane Arnold Energy Center cc:
Mr. J. A. Stall Senior Vice President, Nuclear and Chief Nuclear Officer Florida Power & Light Company P. O. Box 14000 Juno Beach, FL 33408-0420 Mr. M. S. Ross Managing Attorney Florida Power & Light Company P. O. Box 14000 Juno Beach, FL 33408-0420 Ms. Marjan Mashhadi Senior Attorney Florida Power & Light Company 801 Pennsylvania Avenue, NW Suite 220 Washington, DC 20004 Don E. Grissette Vice President, Nuclear Training and Performance Improvement Florida Power & Light Company P. O. Box 14000 Juno Beach, FL 33408 Steven R. Catron Manager, Regulatory Affairs Duane Arnold Energy Center 3277 DAEC Road Palo, IA 52324 U. S. Nuclear Regulatory Commission Resident Inspector=s Office Rural Route #1 Palo, IA 52324 Mr. Mano Nazar Senior Vice President and Nuclear Chief Operating Officer Florida Power & Light Company P. O. Box 14000 Juno Beach, FL 33408 Mr. D. A. Curtland Plant Manager Duane Arnold Energy Center 3277 DAEC Rd.
Palo, IA 52324-9785 Mr. R. S. Kundalkar Vice President, Nuclear Technical Svcs.
Florida Power & Light Company P. O. Box 14000 Juno Beach, FL 33408 Daniel K. McGhee Iowa Department of Public Health Bureau of Radiological Health 321 East 12th Street Lucas State Office Building, 5th Floor Des Moines, IA 50319-0075 Chairman, Linn County Board of Supervisors 930 1st Street SW Cedar Rapids, IA 52404 Last revised March 20, 2008
SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO REQUEST FOR RELIEF FROM IWE-2500 REQUIREMENTS DUANE ARNOLD ENERGY CENTER DOCKET NO. 50-331
- 1.
INTRODUCTION By letter NG-07-0367 dated May 15, 2007 (Ref. 5.1), as supplemented by letter NG-07-0808 dated October 31, 2007 (Ref. 5.2), FPl Energy Duane Arnold LLC (the licensee), requested relief from the requirements of the the American Society of Mechanical Engineers (ASME)
Boiler and Pressure Vessel Code (the Code),Section XI (1992 Edition, 1992 Addenda),
Subarticle IWE-2500 with regard to VT-3 visual examinations of the reinforcing structure and integral attachment of drywell stabilizers X-58C and X-58G. This relief is requested for the first 10-year interval of the Containment Inspection Program for the Duane Arnold Energy Center (DAEC), which will end on May 21, 2008.
This relief is requested pursuant to Title 10 of the Code of Federal Regulations (10 CFR),
Section 50.55a(a)(3)(ii) 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. This evaluation addresses the merits of the request for relief from code requirements proposed by the licensee.
2.0 REGULATORY EVALUATION
Pursuant to Section 50.55a(a)(3)(ii), proposed alternatives to the requirements of paragraphs (c), (d), (e), (f), (g) and (h) of the section (i.e., 10 CFR 50.55a Codes and Standards) or portions thereof may be used when authorized by the Director of the Office of Nuclear Reactor Regulation, provided the applicant demonstrates that compliance with the specified requirements would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety. The licensee has submitted this relief request, pursuant to 10 CFR 50.55a(a)(3)(ii), seeking relief from the code requirements in 10 CFR 50.55a(g)(4), subject to the limitation in paragraph (b)(2)(vi) and applicable modifications in paragraph (b)(2)(ix), with regard to inservice inspection of drywell stabilizers X-58C and X-58G for its first containment in-service inspection (CISI) interval ending in May 2008.
3.0 TECHNICAL EVALUATION
3.1 Relief Request The licensee is requesting relief, pursuant to 10 CFR 50.55a(a)(3)(ii), from performing the VT-3 visual examinations of the reinforcing structure and integral attachment of Drywell Stabilizers X-58C and X-58G.
3.1.1 Component Identification:
Code Class:
MC Code
Reference:
ASME Code,Section XI, Subsection IWE, Table IWE-2500-1
Examination Category:
E-A Item Number:
E1.12
==
Description:==
Drywell stabilizer manhole cover frames and welded attachments behind the covers Component Numbers:
Drywell Stabilizers X-58C and X-58G 3.1.2 Applicable code edition and addenda:
ASME Boiler and Pressure Vessel Code,Section XI, 1992 Edition, 1992 Addenda 3.1.3 Applicable code requirement from which relief is requested:
ASME Code Section XI (1992 Edition, 1992 Addenda) Subarticle IWE-2500, Table IWE-2500-1 Category E-A, Item E1.12, requires VT-3 visual examinations of manhole frames and attachment welds between structural attachments and the pressure retaining boundary.
3.1.4 Licensees Reason and Basis for Request:
The licensee stated that the DAEC construction permit was issued in 1970, and the operating license was issued in 1974. The ASME Code Section III, Class B, 1968 Edition with the Summer 1968 Addenda and Code Cases 1177, 1330, and 1413 were used for the design, fabrication, and testing of the DAEC Primary Containment. The upper elevation drywell coolers were installed in the drywell in 1987. In 1996, the Nuclear Regulatory Commission (NRC) amended its regulations to incorporate by reference Section Xl of the ASME Code, and thus mandated licensees to revise their CISI program in accordance with this code. Accordingly, DAEC adopted the 1992 Edition and the 1992 Addenda of Subsection IWE of the ASME Code Section XI for its CISI program. The parameters for accessibility for in-service inspection were not requirements at the time the drywell coolers were installed, and therefore not necessarily factored into component and system configurations, thereby creating conditions where ASME Section XI Code-required examinations for some containment components became impractical.
The licensee stated that to examine the manhole frame and to examine the drywell stabilizer attachment welds, the drywell stabilizer manhole covers have to be removed. The upper elevation drywell coolers were installed prior to these VT-3 exam requirements. The upper elevation drywell coolers prohibit the removal of the bolting and the manhole covers for Drywell Stabilizers X-58C and X-58G. The manholes are 16 inches in diameter with 23.5 inch diameter manhole covers bolted to the thickened liner plate around the manhole using 16 threaded studs and double hex nuts. The studs are one inch in diameter and 6 inches in length. Without removal of the bolting, the integral attachment and the associated reinforcing structure cannot be examined. In order to perform the VT-3 visual examination, the drywell coolers would have to be moved. According to the licensee, this removal would require extensive modification in the drywell. The licensee further stated that examination of the Drywell Stabilizers X-58C and X-58G, which includes their reinforcing structure and the integral attachment to the outside surface of the drywell, has only a small potential of increasing plant safety margins and a very disproportionate impact on expenditures of plant manpower and radiation exposure.
The licensee has, therefore, requested the stated relief in accordance with 10 CFR 50.55a(a)(3)(ii), on the basis that compliance with the specified code requirements would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety.
3.1.5 Proposed Alternative and Duration:
Pursuant to 10 CFR 50.55a(a)(3)(ii), the DAEC requests relief from performing the VT-3 visual examinations of the reinforcing structure and integral attachment of Drywell Stabilizers X-58C and X-58G. There are a total of eight Drywell Stabilizers and associated manhole covers (X-58A through X-58H). Similar relief with respect to examination of X-58A is documented in a previous relief request MC-R008, which was authorized by the NRC by letter dated December 13, 2000 (ADAMS Accession No. ML003777130). According to the licensee, the remaining five Drywell Stabilizers have been examined with acceptable results.
The relief is requested for the first 10-year interval of the Containment Inspection Program for the DAEC, which will end on May 21, 2008.
3.1.6 Staff Evaluation:
The licensee stated that the drywell coolers interfere with the removal of manhole covers for drywell stabilizers X-58C and X-58G. The licensee stated that examination of the drywell stabilizers X-58C and X-58G, including their reinforcing structure and integral attachment to the outside surface of the drywell, would require extensive modification of the drywell for removal of the coolers and has only a small potential of increasing plant safety margins and a disproportionate impact on expenditures of plant manpower and radiation exposure.
In its response by letter dated October 31, 2007 (Ref. 5.2) to the first item in the NRC staffs request for additional information (RAI), herein referred to as RAI 1, the licensee provided relevant drawings that showed the relative location, structural configuration and general arrangement of Drywell Stabilizers X-58C and X-58G and the drywell coolers.
In its request for additional information item 2 (RAI 2), the staff requested the licensee to substantiate the statement mentioned in the first paragraph of this section by providing a quantitative estimate of the effort involved, time duration required, the area dose-rate and the resulting personnel dose that could result from radiation exposure for each of these drywell stabilizers, if the VT-3 examinations were to be performed as required by the ASME Code,Section XI.
In its response by letter dated October 31, 2007 (Ref. 5.2), the licensee stated that based on the Engineering Change Package (ECP) that previously replaced 12 drywell coolers in the lower portion of the drywell, the total dose to remove the two subject drywell coolers is estimated to be significantly higher than 3.4 REM per cooler since the involved coolers are in the upper elevations of the drywell where clearances are tighter. The licensee stated that this level of dose would not be consistent with the principles of "As Low As Reasonably Achievable" for the performance of the two visual examinations of Stabilizers X-58C and X-58G.
In order to provide an estimate of the amount of work required to remove the 2500 pound drywell coolers and reinstall them after performing the visual examination, the licensee included
a copy of a detailed "Cooler Moving Plan" from the stated ECP as Enclosure 3 of the response to the staffs RAI (Ref. 5.2). The licensee summarized that the steps for removing the cooler would consist of removing the structural steel, installing a gantry crane, removal of the necessary fasteners, draining the coolers, prying up the coils for removal, and rigging the coils out of the way. Reinstallation would consist of moving the coils back into position with the gantry crane, reinstallation of the fasteners and reinstalling the structural steel. This is considered to be a significant amount of work to allow access to remove the manhole cover to perform the visual examination of Stabilizers X-58C and X-58G. The licensee stated that based on the amount of work involved as outlined in Enclosure 3 of the response to the NRC staffs RAI, it is clear that the time to prepare for, perform, and restore from the inspections would be significant, on the order of weeks.
In the response to the second item in the RAI (RAI 2), the licensee provided a quantitative estimate of the time and effort it would take to perform the required ASME Code examinations and the associated dose exposure. Based on the response to RAI 2, the staff finds that the time and effort required and the radiation exposure that would result from performing the VT-3 examinations of Drywell Stabilizers X-58C and X-58G is significant and would constitute a hardship for the licensee without a compensating increase in the level of quality and safety.
Since there was no alternative physical action(s) proposed in the relief request, in RAI 3, the third item in the RAI, the NRC staff requested that the licensee confirm whether a general visual examination (as proposed in previous Relief Request MC-R008 listed as Precedent 1 in the application letter dated May 15, 2007) of the accessible surfaces of the Drywell Stabilizers X-58C and X-58G has been or will be performed during the current (last) inspection period of the first ten-year interval of the Containment Inspection Program for which the relief is requested. The licensee was requested to discuss the findings, if a general visual examination was already performed, or indicate a schedule if it was planned to be performed. The licensee was also requested to provide information, with schedule and results, if a Type B test was performed on the manhole penetrations of drywell stabilizers X-58C and X-58G during the current inspection interval.
In its response to RAI 3 by letter dated October 31, 2007 (Ref. 5.2), the licensee stated that the drywell stabilizers X-58C and X-58G were included in the general visual examinations (IWE Category E-A, Item Number E1.11) that were completed satisfactorily in Refueling Outage (RFO) RFO19 (conducted in 2005) and RFO20 (conducted in 2007). Also, a more detailed visual examination of the stabilizer shear lug bolting was performed satisfactorily on the bolting of all eight stabilizers in RFO19 (2005) and four of the stabilizers were examined in RFO20 (2007). The licensee emphasized that although 2007 examination results do not distinguish whether X-58C or X-58G were part of the four that were examined, it is important to note that five of the eight stabilizers have been examined under the IWE Program with no indications identified.
The licensee further stated that each of the Drywell Stabilizer Access Ports (X-58A through X-58H) are part of the performance-based containment leakage testing program. They are leak rate tested on a 10-year frequency, and X-58C and X-58G were last local-leak-rate tested (Type B test) in RFO16 (1999) and RFO19 (2005), respectively. The results of both tests were found to be acceptable and met the criteria under 10 CFR Part 50, Appendix J, Option B. The next scheduled Type B test for X-58C and X-58G will be in RFO21 (2009) and RF024 (2014) respectively. Further, the Type A test (integrated leak rate test - ILRT) was last performed in
RFO20 (2007) with a leakage rate of 0.3422 percent weight per day in comparison to the maximum allowable leakage rate, La, of 2.0 percent weight per day.
Based on the above response to RAI 3, the staff finds that all the eight drywell stabilizers have been subjected to a satisfactory general visual examination and detailed visual examination of the shear lug bolting in the recent past (2005 and later). Also, X-58G was subjected to a successful Type B test in 2005 and X-58C will be Type B tested in 2009. Further, the containment ILRT performed in 2007, yielded a leakage rate significantly lower than the allowable maximum rate. Therefore, there is reasonable assurance that the structural and leak-tight integrity of the components of drywell stabilizers X-58C and X-58G that form part of the containment pressure boundary is and will be sound. According to the licensee, five (X-58B, X-58D, X-58E, X-58F & X-58H) of the total of eight (X-58A through X-58H) Drywell Stabilizers and associated manhole covers have been examined with acceptable results. Consequently, requirements of 10 CFR 50.55a(b)(2)(ix)(A) are met, and no further evaluation of the acceptability of inaccessible areas is necessary.
Based on the above, the staff finds that the licensees proposed alternative will provide reasonable assurance of structural and leak-tight integrity of the components of drywell stabilizers X-58C and X-58G forming part of the containment pressure boundary. Therefore, the staff concludes that the requested relief can be authorized, pursuant to 10 CFR 50.55a(a)(3)(ii), on the basis that compliance with the Code requirements would result in a hardship without a compensating increase in the level of quality and safety.
4.0 CONCLUSION
Based on the information provided in the relief request (Ref. 5.1) and the drawings and responses to staffs RAI provided in Ref. 5.2, the NRC staff concludes that the licensees compliance with the specified Code requirement would result in a hardship without a compensating increase in the level of quality and safety, and that the licensees proposed alternative will provide reasonable assurance of structural and leak-tight integrity of the components of drywell stabilizers X-58C and X-58G that form part of the containment pressure boundary. Therefore, the requested relief is authorized, pursuant to 10 CFR 50.55a(a)(3)(ii), for the first 10-year interval of the Containment Inspection Program for the DAEC, which will end on May 21, 2008.
5.0 REFERENCES
- 1.
Letter No. NG-07-0367 dated May 15, 2007, from Gary Van Middlesworth, FPL Energy Duane Arnold, LLC, to USNRC with regard to Relief Request for Drywell Stabilizer Examinations, Duane Arnold Energy Center, Docket No. 50-331, License No. DPR-49 (ML071430227).
- 2.
Letter No. NG-07-0808 dated October 31, 2007, from Richard L. Anderson, FPL Energy Duane Arnold, LLC, to USNRC with regard to Response to Request for Additional Information related to the Relief Request for Drywell Stabilizer
Examinations, Duane Arnold Energy Center, Docket No. 50-331, License No.
Principal Contributors: George Thomas Hansraj Ashar Date: May 1, 2008