NL-18-1041, Proposed Alternative for the Fifth Interval Inservice Inspection FNP-ISI-AL T-05-04, Version 1.0

Proposed Alternative for the Fifth Interval Inservice Inspection FNP-ISI-AL T-05-04, Version 1.0

ML19067A213
Person / Time
Site:	Farley
Issue date:	03/08/2019
From:	Gayheart C Southern Nuclear Operating Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
NL-18-1041
Download: ML19067A213 (9)

Text

~ Southern Nuclear Cheryl A. Gayheart Regulatory Affairs Director 3535 Colonnade Parkway Birmingham, AL 35243 205 992 5316 tel M.~R 0 8 2019 205 992 7601 fax Docket Nos.: 50-348 NL-18-1041 50-364 U.S. Nuclear Regulatory Commission ATIN: Document Control Desk Washington, D. C. 20555-0001 Joseph M. Farley Nuclear Plant- Units 1 and 2 Proposed Alternative for the Fifth lntervallnservice Inspection FNP-ISI-ALT 04, Version 1.0 Ladies and Gentlemen:

Pursuant to 10 CFR 50.55a(z)(1 ), Southern Nuclear Operating Company (SNC) hereby submits Proposed Alternative FNP-ISI-ALT-05-04, Version 1.0. This alternative proposes use of an alternate IWL examination schedule for performing the 45th Unit 1 IWL surveillance activities and 40th Unit 2 IWL surveillance activities at Joseph M. Farley Nuclear Plant (FNP) during the Fifth lnservice Inspection (lSI) Interval, which began December 1, 2017. This alternative also proposes a one-time exemption for Unit 1 from the examination frequency requirement in Table IWL-2521-2.

The basis for the proposed alternative for FNP Unit 1 and Unit 2 is provided in the Enclosure to this letter.

This letter contains no NRC commitments. If you have any questions, please contact Jamie Coleman at 205.992.6611.

Respectfully submitted, Clieryl Regulatory Affairs Director CAG/tle/scm

Enclosure:

Proposed Alternative FNP-ISI-ALT-05-04, Version 1.0, in accordance with 10 CFR 50.55a(z)(1) cc: Regional Administrator, Region II NRR Project Manager- Farley Nuclear Plant Senior Resident Inspector- Farley Nuclear Plant RTYPE: CFA04.054

Joseph M. Farley Nuclear Plant- Units 1 and 2 Enclosure Proposed Alternative FNP-181-ALT-05-04, Version 1.0, in accordance with 10 CFR 50.55a(z)(1)

Enclosure to NL-18-1 041 Proposed Alternative FNP-ISI-ALT-05-04, Version 1.0, in accordance with 10 CFR 50.55 a(z)(1)

Plant Site- Unit: Joseph M. Farley Nuclear Plant (FNP)- Unit 1 and Unit 2 Interval Dates: 5th lnservice Inspection (lSI) Interval- December 1, 2017 through November 30, 2027 Requested Date Approval is requested by September 8, 2019.

for Approval:

Unit 1 containment is scheduled to undergo the tendon anchorhead replacement project starting in June 2019. This tendon anchorhead replacement project is expected to take four to six months to complete. The IWL surveillance is scheduled to immediately begin once the replacement project is completed. The requested approval date will allow the vendor to complete the anchorhead replacement and immediately enter the IWL surveillance.

This approval will also allow a one-time exemption for Unit 1 from the examination frequency requirement in Table IWL-2521-2. It is proposed that the initial examination of the repair/replacement population be performed at the next regularly scheduled IWL examination (Unit 1 soth year (i.e., July 2026)).

ASME Code The American Society of Mechanical Engineers (ASME) Code components Components associated with this alternative are the unbonded post-tensioning system Affected: tendons and concrete that are part of the Reactor Containment Building.

Category and System Details:

ASME Code Class: Concrete Containment (CC)

1. Subsection: Table IWL-2500-1

Description:

Examination Category L-A, Concrete and Examination Category L-8, Unbonded Post-Tensioning System The affected components associated with Table IWL-2500-1 for the proposed early surveillance following post-tensioning system anchorhead replacement activities scheduled to commence in Spring 2019 are:

• 18 randomly selected tendons (3 vertical tendons, 3 dome tendons, and 3 hoop tendons per unit),

• 1 hoop tendon for Unit 1 randomly selected from the augmented repair/replacement scope related to the 2012 failure, i.e., from the first augmented examination group.

• the containment concrete for the 45th Unit 1 and 40th Unit 2 IWL surveillances.

E-1

Enclosure to NL-18-1041 Proposed Alternative FNP-ISI-ALT 04, Version 1.0, in accordance with 10 CFR 50.55 a(z)( 1)

2. Subsection: Table IWL-2521-2

Description:

Augmented Examination Requirements Following Post-Tensioning System Repair/Replacement Activities The affected components for the augmented examination requirements per Table IWL-2521-2 following post-tensioning system anchorhead replacement activities scheduled to commence in Spring 2019, i.e., the second augmented examination group, are up to 15 hoop tendons on Unit 1. These hoop tendons will undergo field end anchorhead replacement related to the corrective action based on the failure of H11AB as part of the extent of condition inspection associated with this effort. Namely:

Tendon To be Comment Identifier Replaced?

H1AC Yes In same lot as previously replaced H11A8.

H18C Yes In same lot as previously replaced H11 A8.

H38C Yes In same lot as previously replaced H11 A8.

H58C Yes In same lot as previously replaced H11A8.

H78C Yes In same lot as previously replaced H11A8.

H9AB Yes In same lot as previously replaced H11A8.

H138C Yes In same lot as previously replaced H11 A8.

H15A8 Yes In same lot as previously replaced H11 A8.

H158C Yes In same lot as previously replaced H11 A8.

H29AC Yes In same lot as previously replaced H11A8.

H31AC Yes In same lot as previously replaced H11A8.

In different lot than that of H11 A8. Replacing and testing H37A8 Yes to confirm extent of condition .

In different lot than H11 A8. SNC will apply its Corrective Action Program per 10 CFR Appendix 8 , Criterion XVI to H7AC Contingent initiate replacement based on test results of H37A8, if necessary.

In different lot than H11 AB. SNC will apply its Corrective Action Program per 10 CFR Appendix 8, Criterion XVI to H9AC Contingent initiate replacement based on test results of H37A8, if necessary.

In different lot than H11 A8. SNC will apply its Corrective Action Program per 10 CFR Appendix 8 , Criterion XVI to H15AC Contingent initiate replacement based on test results of H37A8 , if necessary.

E-2

Enclosure to NL-18-1041 Proposed Alternative FNP-ISI-ALT 04, Version 1.0, in accordance with 10 CFR 50.55 a(z)( 1)

Applicable Code The applicable Code edition and addenda is ASME Section XI, "Rules for Edition and lnservice Inspection of Nuclear Power Plant Components," 2007 Edition through Addenda: the 2008 Addenda.

Applicable Code Subsection IWL-2500 of the ASME Section XI Code states that examination shall Requirements: be performed in accordance with the requirements of Table IWL 2500-1.

Subsection IWL-2521.2 of the ASME Section XI Code states that tendons affected by repair/replacement activities shall require augmented examination in accordance with Table IWL-2521-2. Table IWL-2521-2 requires an initial inspection one year (+1- three months) following completion of an IWL repair/replacement activity that affects the containment post-tensioning system.

Table IWL-2521-2 also indicates that subsequent lnservice Inspections will coincide with IWL-2420, Unbonded Post-Tensioning Systems, following completion of repair/replacement activities.

IWL sections referenced in this proposed alternative are:

IWL-2400, lnservice Inspection Schedule, IWL-241 0, Concrete, IWL-2420, Unbounded Post-Tensioning Systems, IWL-2500, Examination Requirements, IWL-2521, Tendon Selection, IWL-2523, Tendon Wire and Strand Sample Examination and Testing.

Background:

The containment post-tensioning system consists of horizontal, dome, and vertical tendons based on the spatial orientation around the Containment Building. A total of 135 horizontal tendons are anchored at three vertical buttresses. Three groups of dome tendons, for a total of 93 tendons, are anchored at the vertical face of the dome ring girder. A total of 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, except one horizontal tendon was not installed on Unit 2 during construction; therefore, there are only 134 horizontal tendons on Unit 2.

On May 3, 2012, the Unit 1 field end anchorhead on horizontal tendon H7AB failed. On April14, 2017, the Unit 1 field end anchorhead on horizontal tendon H 11 AB failed. The failed horizontal tendon field anchorheads are part of the post-tensioning system for the Unit 1 FNP Reactor Containment Building.

A causal evaluation was performed due to the anchorhead failure and determined that H7AB and H11AB were both part of the same heat treatment certification lot. Of the certification lot, twelve anchorheads remain that are E-3

Enclosure to NL-1 B-1 041 Proposed Alternative FNP-ISI-ALT-05-04, Version 1.0, in accordance with 10 CFR 50.55 a(z)(1) currently installed on Unit 1 Containment. Based on the ALTRAN analysis, hydrogen embrittlement along with improper heat treatment is the most likely cause of the anchorhead failures. Of these remaining twelve tendons, one (H 11 BC) will not be replaced during the Spring 2019 anchorhead project due to its location in the Penetration Room Filter (PRF) barrier. Based on the failure trend and the ALTRAN analyses performed, the replacement of the remaining eleven field end anchorheads within this lot will reduce the likelihood of future failures. Tendon H11 BC may be de-tensioned to lessen likelihood of its failure.

SNC analysis demonstrates that containment operability will not be affected if H11 BC is de-tensioned.

In addition, anchorhead (H37AB), not in the affected certification lot, is being replaced and tested to further knowledge in confirming the extent of condition.

Based on the results of testing on H37AB, three additional anchorheads with similar properties to H37AB may be replaced.

Since the number of Unit 1 horizontal tendons affected by the anchorhead replacement project (at least twelve, up to fifteen) is greater than 5% of the total number of horizontal tendons (i.e., 135), the required sample size for augmented examination, per Table IWL-2521-2, is one horizontal tendon (i.e., the lesser of 4% of the affected tendons or ten tendons).

Reason for The lSI Program commitments to the ASME Section XI, 2007 Edition through the Request: 2008 Addenda, Section IWL-2400, Section IWL-2500, and Table IWL-2500-1 establish the specified dates following the completion of the containment Structural Integrity Test and every five years thereafter(+/- 1 year). The current prescribed schedule for the lSI examination of the concrete and containment tendons is July 2021 +1- 1 year. The containment tendon field end anchorhead replacement project is scheduled to begin in June 2019 and is scheduled to end approximately four to six months later (i.e., possibly as soon as September 2019), which is prior to the allowed time to perform the IWL examinations.

This alternative is being submitted to propose a one-time exemption from the examination frequency requirement in Table IWL-2500-1. It is proposed that the next regularly scheduled IWL examinations, including the first Unit 1 augmented examination group, (45 1h year for Unit 1 and 401h year for Unit 2) commence immediately after the anchorhead replacement projects ends (as soon as September 2019), which would be up to ten months sooner than prescribed by the applicable Code requirements (i.e., July 2020 using the year grace period). FNP still wishes to use the +1- 12-month grace period allowed by IWL-2420(c) for the next regularly scheduled tendon examination if needed for scheduling optimization. Please note that the examination window for E-4

Enclosure to NL-18-1041 Proposed Alternative FNP-ISI-ALT-05-04, Version 1.0, in accordance with 10 CFR 50.55 a(z)(1) subsequent examinations is not changing (i.e., the subsequent examination will be performed July 2026 +1- 1 year).

The one-time exemption will also allow the deferral of performing the initial inspection of the augmented scope of up to fifteen tendons affected by the H 11 AB failure extent of condition. The 1-year (+1- 3 months) inspection prescribed in Table IWL-2521-2 will instead be performed during the next regularly scheduled IWL examination (July 2026, +1- 1 year).

Proposed Discussion I Analysis:

Alternative and The purpose for conducting the inspections is to monitor the post-tensioning Basis for Use:

system for degradation and to verify that actual loss of pre-stress is consistent with predicted values used in design and that the required minimum pre-stress for the containment system is being met. Moving the regularly scheduled IWL examinations up by ten months or less would not have a detrimental effect in evaluating that the minimum pre-stress for the containment system is meeting the required values. Because the tendon prestress loss has shown minimum change over the last two inspections, performing the next regularly scheduled IWL examination as scheduled (July 2026, +1- 1 year) would also not be detrimental.

The replacement anchorhead replacement project requires the new anchorheads to be manufactured with a lower Rockwell "C" hardness number (i.e., 38 +1- 1) to improve resistance to hydrogen embrittlement failure. The horizontal tendons that are affected by the anchorhead replacement project utilize the same pre-stressing system, and will be exposed to, or protected from, the same outside environment as the existing tendons, which have been in service for the last forty-plus years. Ten lSI examinations have been completed to date for Unit 1.

The existing horizontal tendons have met all the post-tensioning test and examination acceptance criteria. The replacement activities that impact the horizontal tendons will not result in any unique condition that may subject the horizontal tendons to a different potential for structural or tendon deterioration.

For new containments, the main reason for performing the one-year tendon inspection, as required by sub-article IWL-2420, is to benchmark the tendon losses shortly after the Structural Integrity Test (SIT) when pre-stress losses (which are due to elastic shortening, creep, shrinkage and relaxation) occur at the highest rate. For the re-tensioned tendons in the FNP containment structure, pre-stress losses will be much smaller than those for the original tendons.

Elastic shortening:

The elastic shortening loss is a function of the pre-stress load, the elastic modulus for the steel tendon and the elastic modulus of the concrete. The pre-stress load and tendon material are identical to the original design. The E-5

Enclosure to NL-18-1041 Proposed Alternative FNP-ISI-ALT-05-04, Version 1.0, in accordance with 10 CFR 50.55 a(z)(1) elastic shortening loss for the re-tensioned tendons will therefore be unaffected.

Creep:

Creep is a time dependent function of the concrete. Creep is represented by a creep coefficient which is the ratio of creep strain to elastic strain. The creep loss will be the same for the re-tensioned tendons.

Relaxation :

Steel relaxation losses will be lower for the re-tensioned tendons because of the shorter remaining life of the plant.

Shrinkage:

Shrinkage losses will similarly be the same.

The tendons will be re-tensioned to a value above the predicted losses but less than 70% of the specified ultimate tensile strength of the tendon per IWL- 2523.3(a).

Since the losses in the re-tensioned horizontal tendons is less than the original design losses (tendons re-tensioned to values above these predicted forces),

there is additional margin in the post-tensioning system.

There is a high degree of confidence that the postponement of the first scheduled inspection of the re-tensioned horizontal tendons affected by the anchorhead replacement project until the next regularly scheduled IWL examination (July 2026, +1- 1 year) will not involve an increase in radiological risk and would not adversely affect public health and safety.

Additional Considerations:

To perform tendon examinations, a large mobile crane must be located near the Containment Building to lift tendon work platforms and the hydraulic rams used to perform tendon tension tests. There are some inherent risks associated with these rigging and lifting activities. Approving this alternative to move the IWL surveillance up by ten months or less would avoid these risk sources by performing only one examination staging; that is, combining the anchorhead replacement project with the IWL examination. Similarly, delaying the augmented examination of the tendons affected by the anchorhead replacement project also avoids the risk sources of an additional rigging and lifting activity.

Conclusion:

Therefore, it is proposed that the IWL examination in accordance with ASME Section XI, 2007 Edition through the 2008 Addenda, Section IWL-2400, IWL-2500, and Table IWL-2500-1 be performed up to ten months prior to the allowed inspection timeframe. In addition, it is proposed that the first scheduled E-6

Enclosure to NL-18-1041 Proposed Alternative FNP-ISI-ALT-05-04, Version 1.0, in accordance with 10 CFR 50.55 a(z)(1) augmented examination of the horizontal tendon affected by the anchorhead replacement project be delayed until the next regularly scheduled IWL examination (July 2026, +1- 1 year). There would be no deviation from Section XI requirements for subsequent lnservice Inspections since they would be scheduled every five years(+/- one year) as required by Table IWL-2500-1 and paragraph IWL-241 0 and IWL-2420. SNC considers that this proposed alternative schedule will provide an acceptable level of quality and safety, consistent with the provisions of 10 CFR 50.55a(z)(1 ).

Duration of This alternative is requested for the remainder of the current Fifth lnservice Proposed Relief Inspection Interval, which began December 1, 2017 and is scheduled to end on Request: November 30, 2027.

Precedent: Joseph M. Farley Nuclear Plant- Unit 1, received approval of a relief request to delay an lSI Program commitment to the ASME Section XI, 2001 Edition through the 2003 Addenda, Section IWL-2521.2 and Table IWL-2521-2 establishing the specific requirement for the initial inspection at one year (+1- three months) following the completion of repair/replacement activities. The approval allowed the initial inspection to occur concurrent with the next regularly scheduled IWL examination at that time, or up to nearly three years (i.e., July 2017 with the one-year grace period) after the prescribed date (i.e., nominally September 2014).

(ML14169A195)

Reference:

ASME Section XI 2007 Edition through the 2008 Addenda.

Status: Pending NRC Approval.

E-7