ML14169A195

Alternative Request Regarding Containment Building Tendon Examination Schedule

ML14169A195
Person / Time
Site:	Farley
Issue date:	07/11/2014
From:	Robert Pascarelli Plant Licensing Branch II
To:	Pierce C Southern Nuclear Operating Co
Williams S
References
TAC MF3488
Download: ML14169A195 (8)

Text

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 July 11, 2014 Mr. C. R. Pierce Regulatory Affairs Director Southern Nuclear Operating Company, Inc.

P. 0. Box 1295 I Bin- 038 Birmingham, AL 35201-1295

SUBJECT:

JOSEPH M. FARLEY, UNIT 1 -ALTERNATIVE REQUEST REGARDING CONTAINMENT BUILDING TENDON EXAMINATION SCHEDULE (TAG NO. MF3488)

Dear Mr. Pierce,

By letter dated February 18, 2014, as supplemented by letters dated April 22 and June 16, 2014, Southern Nuclear Operating Company, Inc., (SNC) requested an alternative to Table IWL-2521-2 of American Society of Mechanical Engineers (ASME) Code Section XI, 2001 Edition through the 2003 Addenda for Joseph M. Farley Nuclear Plant, (FNP) Unit 1. The ASME Code components associated with this alternative are the tendons that are part of the reactor containment building. SNC requested to use an alternative tendon examination schedule to the requirements in Table IWL-2521-2.

The application was submitted pursuant to Sections 50.55a(a)(3)(i) of Title 10 of the Code of Federal Regulations (1 0 CFR), which requires that the applicant demonstrate that the proposed alternative provides an acceptable level of quality and safety.

The NRC staff has reviewed the subject request, and concludes that SNC has adequately addressed all of the regulatory requirements and that the proposed alternative provides an acceptable level of quality and safety. Therefore, the NRC staff authorizes the proposed alternative in accordance with 10 CFR 50.55a (a)(3)(i). The NRC staff's safety evaluation is enclosed.

C. Pierce If you have any questions, pleasecontact the Project Manager, Shawn Williams, at 301-415-1009 or via e-mail at Shawn.Williams@nrc.gov.

Sincerely, Robert J. Pascarelli, Chief Plant Licensing Branch 11-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-348

Enclosure:

Safety Evaluation cc w/encl: Distribution via Listserv

SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION ALTERNATIVE TO ASME CODE REQUIREMENTS FOURTH TEN-YEAR INSERVICE INSPECTION PROGRAM INTERVAL SOUTHERN NUCLEAR OPERATING COMPANY JOSEPH M. FARLEY NUCLEAR PLANT, UNIT 1 DOCKET NO. 50-348

1.0 INTRODUCTION

By letter dated February 18, 2014 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML14050A382), as supplemented by letters dated April 22 and June 16,2014 (ADAMS Accession Nos. ML14113A533 and ML14167A277, respectively)

Southern Nuclear Operating Company, Inc., (SNC) requested an alternative to Table IWL-2521-2 of American Society of Mechanical Engineers (ASME) Code Section XI, 2001 Edition through the 2003 Addenda for Joseph M. Farley Nuclear Plant, (FNP) Unit 1. The ASME Code components associated with this alternative are the tendons that are part of the reactor containment building. SNC requested to use an alternative tendon examination schedule to the requirements in Table IWL-2521-2.

Specifically, pursuant to Title 10 of the Code of Federal Regulations (CFR) 10 CFR Part 50, Section 50.55a(a)(3)(i), the licensee requested to use the proposed alternative on the basis that the alternative provides an acceptable level of quality and safety.

2.0 REGULATORY EVALUATION

The 10 CFR 50.55a(g) specifies that in-service inspection (lSI) of nuclear power plant components shall be performed in accordance with the requirements of the ASME Code,Section XI. 10 CFR 50.55a(a)(3) states that alternatives to the requirements of paragraph (g) may be used, when authorized by the NRC, if (i) the proposed alternatives would provide 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 Subsection IWL-2521.2 "Tendons Affected-by Repair/Replacement Activities," and Table IWL-2521-2 of ASME Code Section XI, 2001 Edition including Addenda through 2003, require -

augmented examination of tendons affected by post-tensioning system repair/replacement activities. Table IWL-2521-2 of ASME Code Section XI, 2001 Edition through the 2003 Addenda requires an initial inspection of tendons affected by post-tensioning system repair/replacement activities within one year (plus or minus 3 months) following the completion of repair/replacement activities.

Based on th~ above and subject to the NRC's findings with respect to authorizing the proposed alternati<te to the ASME OM Code given below, the NRC staff finds that regulatory authority exists for the licensee to request and the Commission to authorize the alternative requested by the licensee.

3.0 TECHNICAL EVALUATION

3.1 Background By letter dated February 18, 2014, SNC requested, for FNP Unit 1, an alternative to Table IWL-2521-2, "Augmented Examination Requirements Following Post-Tensioning System Repair/Replacement Activities," of American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME)Section XI, 2001 Edition through the 2003 Addenda, which requires an initial examination of tendons affected by post-tensioning system repair/replacement activities within one year (plus or minus 3 months) following the completion of repair/replacement activities. The alternative FNP-ISI-ALT-14, Version 1.0, proposes the use of an alternate tendon examination schedule for tendons affected by repair/replacement activities at FNP Unit 1, during the fourth containment in-service inspection interval, which began December 1, 2007 and ends on November 30, 2017.

As stated in Reference 5.1, on May 3, 2012, the field-end anchorhead on horizontal tendon field anchorhead (H7AB) failed. The (H7AB) is part of the post-tensioning system for the Unit 1 FNP containment building. The post-tensioning system consists of horizontal, dome, and vertical tendons. A total of one hundred thirty-five {135) horizontal tendons are anchored at three vertical buttresses. Three groups of dome tendons, for a total of ninety-three (93) tendons, are anchored at the vertical face of the dome ring girder. One hundred thirty {130) vertical tendons are anchored at the top surface of the ring girder and at the bottom of the base slab. The number of tendons is the same for both Units 1 and 2 containment building, except one horizontal tendon was not installed on Unit 2 during construction; therefore, there are only one hundred thirty-four (134) horizontal tendons in Unit 2 containment building. The licensee stated that the root cause investigation, performed due to the anchorhead failure, called for the replacement of one (1) failed tendon (H7AB) with its field anchorhead and the removal, testing, and replacement of fqurteen (14) additional field anchorheads. A total of fifteen (15) different tendons from Units 1 and 2 were affected by the anchorhead replacement activities. The failed tendon, H7 AB on Unit 1, was completely replaced. The other fourteen (14) tendons were temporarily detensioned, the field end anchorhead replaced, and subsequently retensioned.

For Unit 1, ten {1 O) horizontal tendons, one {1) dome tendon, and zero {0) vertical tendon were affected by replacement activities. For Unit 2, one {1) horizontal tendon, two (2) dome tendons, and one (1) vertical tendon were affected by replacement activities.

Per Table IWL-2521-2, the lesser of 4 percent of the affected tendons or ten tendons is the required sample size when the number of affected tendons is greater than or equal to 5 percent.

If less than 3 tendons are affected, then there is no required sample size for augmented examinations. The licensee provided the following table which summarizes the number of affected tendons and required sample size for augmented examinations for both FNP units.

.Unit and Type of Total Number of 5 percent of Number (N) of Required Tendon Tendons Tendons Affected Tendons Sample Size (rounded)

U 1 Horizontal 135 6 10 1 U1 Vertical 130 6 0 N/A U1 Dome 93 4 1 N/A U2 Horizontal 134 6 1 N/A U2 Vertical 130 6 1 N/A U2 Dome 93 4 2 N/A Since the number of horizontal tendons on Unit 1 affected by the repair/replacement activities (ten) are greater than 5 percent of the total, the required sample size, according to Table IWL-2521-2, is one horizontal tendon (i.e., the lesser of 4 percent of the affected tendons or ten tendons). No other type of tendon meets the threshold as can be seen in the table above.

The provision in IWL-2521.2 requires that this horizontal tendon be randomly selected from the population of horizontal tendons affected by the repair/replacement activities.

The repair/replacement activities began in December 2012 and concluded in September 2013.

According to Table IWL-2521-2, the initial examination due date is one year(+/- three months) from the conclusion of the repair/replacement activities. Therefore, the schedule for the initial inspection of the sample of one horizontal tendon is September 2014 (+/-three months).

The licensee requested to defer the initial inspection of the sample of one horizontal tendon to the next regularly scheduled tendon examinations (401h year), tentatively scheduled for July 2016. The licensee indicated in its letter dated February 18, 2014, that the 12-month grace period allowed by IWL-2420(c), for the next regularly scheduled tendon examination may be used for scheduling optimization.

The Nuclear Regulatory Commission (NRC) staff's review addresses the ability of the licensee to maintain an acceptable level of quality and safety and to ensure integrity of the containment post-tensioning system when the initial inspection of horizontal tendons affected by the post-tensioning repair/replacement activities is performed in July 2016 (plus or minus one year) in lieu of September 2014 (plus or minus 3 months) following the repair/replacement activities.

3.2 ASME Code Components Affected

Class CC Components. Post-Tensioning Horizontal Tendons This alternative applies to ten (1 0) horizontal tendons that were affected by the FNP Unit 1, tendon H7AB repair/replacement activities. The specific. components affected are: (1) Tendon H7AB (tendon and field anchorhead replaced); (2) Tendons H25AC, H27AC, H28BC, H29AB, H30AC, H33AB, H35AB, H41AB, and H44AB (field anchorhead replaced).

3.3 Applicable Code Edition and Addenda The licensee stated, in Reference 5.1, that FNP Unit 1, current code of record for the fourth containment in-service inspection interval is the ASME Code,Section XI, 2001 Edition through the 2003 Addenda.

3.4 Applicable ASME Code Requirement Table IWL-2521-2 of ASME Code Section XI, 2001 Edition through the 2003 Addenda requires an initial examination of tendons affected by post-tensioning system repair/replacement activities within one year (plus or minus 3 months) following the completion of repair/replacement activities.

3.5 Licensee Proposed Alternative and Basis for Use As an alternative to Table IWL-2521-2 of ASME Code,Section XI, the licensee requested to perform the initial inspection of the sample of one horizontal tendon affected by the repair activities in July 2016 (plus or minus one year) in lieu of September 2014 (plus or minus 3 months) following repair/replacement activities. This alternative is proposed for the fourth 10-year in-service inspection interval which began on December 1, 2007 and ends on November 30, 2017.

The licensee indicated that (1) nine ISis have been completed to date and the existing horizontal tendons have met all the post-tensioning test and examination acceptance criteria, (2) the planned repair/replacement activities affecting the horizontal tendons did not result in any unique condition that may subject the horizontal tendons to a different potential for structural or tendon deterioration, and (3) the affected horizontal tendons were retensioned to a value above the predicted tendon force but less than the original tendon seating force (0. 7 times the ultimate tendon strength) and will be subject to prestress losses smaller than those for the original tendons. As such, this alternative provides an acceptable level of quality and safety, and does not adversely impact the health and safety of the public.

3.6 NRC Staff Evaluation As the licensee indicated, nine ISis have been completed to date and the horizontal tendons have met all the post-tensioning test and examination acceptance criteria. '

The NRC staff identified areas in which additional information was necessary to complete the evaluation of the licensee's proposed alternative. Therefore, the NRC staff issued request for additional information to obtain further information relative to the magnitude of horizontal tendon prestressing force and the inspection results of the affected horizontal tendons.

In SNCs letter dated April 22, 2014, and June 16, 2014, the licensee provided the required horizontal tendon force, according to the FNP Unit 1, current licensing basis, along with the minimum predicted force for the population of the affected horizontal tendons at the time of the 401h year tendon surveillance (July 2016) and at one year later (July 2017) considering the 12-month grace period allowed by IWL-2420(c) of ASME Code,Section XI. The predicted tendon forces for the FNP Unit 1, affected horizontal tendons are greater than the required horizontal tendon force satisfying the containment structure design basis requirements.

In SNCs letter dated April 22, 2014, the licensee also provided the inspection results performed on the field-end of those horizontal tendons affected by the repair/replacement activities. The licensee indicated that 12 ounces of water was observed in horizontal tendon H28BC; but, the tendon anchorage area components (buttonheads, anchorhead, shims and bearing plate) had acceptable level of corrosion (no visible rust or no evidence of progressive rust). The licensee

also indicated that no water was observed in other affected tendons and the corrosion level for tendon anchorage components was found acceptable or was restored to an acceptable level.

4.0 CONCLUSION

Based on the information provided in the licensee's submittals dated February 18, 2014, April 22, 2014 and June 16, 2014, the NRC staff concludes that the licensee's proposed alternative to the requirements of Table IWL-2521-2 of ASME Code,Section XI, 2001 Edition through the 2003 addenda is acceptable because it will provide an acceptable level of quality and safety. Therefore, pursuant to 10 CFR 50.55a(a)(3)(i) the implementation of the licensee-proposed alternative is authorized for the FNP Unit 1, fourth 10-year in-service inspection interval which began on December 1, 2007 and ends on November 30, 2017.

This authorization is limited to those components described in Section 3.2 of this safety evaluation.

All other ASME Code,Section XI requirements for which an alternative was not specifically requested and approved remain applicable, including a third-party review by an Authorized Nuclear In-service Inspector.

5.0 REFERENCES

5.1 Letter from C. R. Pierce (Southern Nuclear Operating Company) to U.S. NRC Document Control Desk, Joseph M. Farley Nuclear Plant- Unit 1 Docket No. 50-348, Proposed Alternative FNP-ISI-ALT-14, Version 1.0, for the Fourth Interval In-Service Inspection, dated February 18, 2014 (ADAMS Accession No. ML14050A382) 5.2 Letter from C. R. Pierce (Southern Nuclear Operating Company) to U.S. NRC Document Control Desk, Joseph M. Farley Nuclear Plant - Unit 1 Response to the Request for Additional Information Regarding lSI Program Alternative FNP-ISI-ALT-14, Version 1.0, dated April 22, 2014 (ADAMS Accession No. ML14113A533).

5.3 Letter from C. R. Pierce (Southern Nuclear Operating Company) to U.S. NRC Document Control Desk, Joseph M. Farley Nuclear Plant- Unit 1 Supplemental Response to Request for Additional Information Regarding lSI Program Alternative FNP-ISI-ALT-14, Version 1.0, dated June 16, 2014 (ADAMS Accession No. ML14167A277)

Principle Contributor:

Farhad Farzam, NRR/DE/EMCB

C. Pierce If you have any questions, please contact the Project Manager, Shawn Williams, at 301-415-1009 or via e-mail at Shawn.Williams@nrc.gov.

Sincerely,

/RAJ Robert J. Pascarelli, Chief Plant Licensing Branch 11-1 Division of Operating Reactor Licensing

• Office of Nuclear Reactor Regulation Docket No. 50-348

Enclosure:

Safety Evaluation cc w/encl: Distribution via Listserv r

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