L-PI-13-089, Supplement to Aging Management Program Submittals

Supplement to Aging Management Program Submittals

ML13284A081
Person / Time
Site:	Prairie Island
Issue date:	10/08/2013
From:	Jeffery Lynch Northern States Power Co, Xcel Energy
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
L-PI-13-089, TAC MF0052, TAC MF0053
Download: ML13284A081 (6)

Text

XcelEnergy OCT 0 8 2013 L-PI-13-089 U S Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Prairie Island Nuclear Generating Plant Units 1 and 2 Dockets 50-282 and 50-306 Renewed License Nos. DPR-42 and DPR-60 ......

Supplement to Prairie Island Nuclear Generating Plant (PINGP) Aging Management Program Submittals (TAC Nos. MF0052 and MF0053)

By letter dated October 1, 2012 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML12276A041), Northern States Power Company, a Minnesota corporation, doing business as Xcel Energy (hereafter "NSPM"), submitted an aging management program (AMP) for the reactor vessel internals (RVI) at PINGP, Units 1 and 2. Letters dated March 7, 2013 (ML13067A284) and March 22, 2013 (ML13084A378) provided additional AMP information. The Enclosure to this letter provides responses to NRC requests for additional information (RAIs) 2-2, 2-3 and 2-4 provided in a letter dated September 18, 2013 (ML13253A122). Pursuant to a teleconference with the NRC Staff on August 27, 2013, NSPM will provide the response to RAI 2-1 at a later date when industry-wide resolution of the issues becomes available.

If there are any questions or if additional information is needed, please contact Mr. Dale Vincent, P.E., at 651-267-1736.

Summary of Commitments This letter contains no new commitments and no revisions to existing commitments.

Ja. Lynch Site Vice President, Prairie Island Nuclear Generating Plant Northern States Power Company - Minnesota Enclosures (1) A Ocvi 1717 Wakonade Drive East a Welch, Minnesota 55089-9642 Telephone: 651.388.1121

Document Control Desk Page 2 cc: Administrator, Region III, Project Manager, PINGP, USNRC USNRC Resident Inspector, PINGP, USNRC

Enclosure Supplement to Prairie Island Nuclear Generating Plant (PINGP) Aging Management Program Submittals (TAC Nos. MF0052 and MF0053)

By letter dated September 18, 2013 (ML13253A122), the NRC requested additional information on the PINGP Reactor Vessel Internals (RVI) Aging Management Program described in submittals dated October 1, 2012 (ML12276A041), March 7, 2013 (ML13067A284), and March 22, 2013 (ML13084A378). Northern States Power Company, a Minnesota corporation, doing business as Xcel Energy (hereafter "NSPM"),

response to the NRC requests for additional information (RAIs) 2-2, 2-3 and 2-4 are provided as follows.

NRC RAI 2-2:

In the licensee's March 22, 2013, submittal it is not evident which of the [Reactor Vessel Internal] RVI components in the PINGP design are specifically defined in the current licensing basis (CLB) as ASME Section Xl, Examination Category B-N-3 removable core support structure components, or how these components relate to the four inspection categories that are defined for Westinghouse-designed RVI components in Technical Report (TR) No. MRP-227-A (i.e., as MRP-defined "Primary Category,"

"Expansion Category," "Existing Program," or "No Additional Measures" components).

Part (a) - Identify all RVI components in the PINGP plant design that are defined in the CLB as ASME Section Xl, Examination Category B-N-3 core support structure components. For each of these components, identify which of the four inspection categories in MRP-227-A is applicable to the component.

Part (b) - If a component identified in the reply to Part (a) is defined as either a "Primary Category" or "Expansion Category" component, identify any differences between the inspections that would be performed on the components under MRP-227-A versus the plant's ASME Section Xl inservice inspection (ISI) program. For each of these components identified in Part (b), clarify how the differences in inspection bases for these components will be reconciled consistent with the CLB for the facility.

NSPM response:

a) The major components which are categorized as B-N-3 removable core support structures and their categorization within MRP-227-A are given in Table 1 below.

The classification of structures with respect to core support function is in conformance with WCAP-14577, Revision 1-A, which is an NRC approved Topical Report.

b) The inspection types required to satisfy ASME Section Xl and MRP-227-A are given in Table 1. Where the requirements differ, both examinations will be performed.

The reason this does not pose a significant redundancy is explained as follows.

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Enclosure The only Primary inspection item that has differing requirements between Section Xl and MRP-227-A is the core barrel. The VT-3 required by Section Xl is a general examination of the entire accessible structure, whereas, the EVT-1 required by MRP-227-A is a much higher resolution examination of only the girth welds and adjacent base metal that is conducted to detect cracking.

For Expansion items, the ASME Section Xl B-N-3 examinations are conducted once per Code interval. Since the Expansion examinations are always the result of indications identified during earlier Primary examinations, Expansion examinations are unlikely to be performed in the same refueling outage as the ASME Section Xl B-N-3 VT-3 exams. Therefore, no duplication or overlap will necessarily result from maintaining the two parallel inspection programs. Also, because the Expansion items have widely varying schedule timelines for their initial performance, reconciling them with the ASME Section Xl B-N-3 examinations for the same component would be very difficult.

Table 1 Reactor Vessel Internals Inspection Types Components classified as Core Examination Category Section Type Support per WCAP-14577 Rev.1-A Section XI MRP-IWB-2500-1 227-A Lower core plate Existing VT-3* VT-3*

Lower core plate fuel alignment pins No Additional Measures VT-3*

Lower support forging Expansion VT-3 EVT-1 Lower support column Expansion VT-3 EVT-1 Core barrel Primary (girth welds, upper VT-3 EVT-1 and lower flange welds)

Expansion (axial welds and VT-3 EVT-1 outlet nozzle welds)

Core barrel flange Existing VT-3* VT-3*

Radial support keys No Additional Measures VT-3*

Baffle plates Primary VT-3 VT-3 Former plates Primary VT-3 VT-3 Upper support assembly Existing VT-3* VT-3*

Upper core plate Expansion VT-3 EVT-1 Upper core plate fuel alignment pins No Additional Measures VT-3*

Upper support columns No Additional Measures VT-3*

Upper core plate alignment pins Existing VT-3* VT-3*

• Requirements for "No Additional Measures" and "Existing" Programs components provided for completeness.

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Enclosure NRC RAI 2-3:

By letter dated March 7, 2013, the licensee provided a response to Action Item 3 that was addressed in the NRC staffs [safety evaluation] SE for the MRP-227-A. In its response to Action Item 3, the licensee provided its basis for why the replacement control rod guide tube (CRGT) assembly support pins (i.e., split pins) at PINGP (which are made from Type 316 cold-worked austenitic stainless steel) would not need to be inspected under the augmented inspection basis in TR MRP-227-A. However, Updated Safety Analysis Report (USAR) Section 3.6.2.2 establishes the following bases with respect to the design of the CRGT assemblies:

The guide tube assemblies, shown on Figure 3.6-3, sheath and guide the control rod drive shafts and control rods and provide no othermechanical functions. They are fastened to the upper support plate and are guided by pins in the upper core plate for proper orientation and support.

Additional guidance for the control rod drive shafts is provided by the upper guide tube which is bolted to the upper support plate and guide tube.

Based on this USAR information, it is not evident why the replacement CRGT split pins would not need to be inspected in accordance with the ASME Section Xl, Table IWB-2500-1, Examination Category B-N-3 ISI requirements, as invoked by the ISI requirements in 10 CFR 50.55a.

Part (a) - Clarify whether the CRGT split pins are defined as ASME Section Xl, Examination Category B-N-3 components for the PINGP CLB. If the CRGT split pins are defined in the CLB as ASME Section Xl, Examination Category B-N-3 core support structure components, justify why the CRGT split pins would not need to be inspected as a part of the "Existing Program" bases of the [Pressurized Water Reactor] PWR Vessel Internals Program or alternatively in accordance with the aging management program (AMP) for the facility that corresponds to GALL AMP XI.M1, "ASME Section Xl Inservice Inspection, Subsections IWB, IWC, and IWD" Program.

Part (b) - Justify why the response to Applicant/Licensee Action Item [A/LAI] #3 did not specifically address whether the ASME Section Xl "Existing Program" bases in the CLB for the CRGT split pins is sufficient for ensuring adequate aging management of the split pins during the period of extended operation. Otherwise, amend the submittal to provide a response to the A/LAI that specifically addresses the adequacy of ASME Section Xl ISI bases for the CRGT split pins and whether these bases are sufficient to manage aging in the components during the period of extended operation.

NSPM response:

(a) Neither the CRGT split pins, nor any part of the CRGT, is considered to provide a core support function. They support and align rod control cluster assemblies, which is a function distinct from core support. As such, the category B-N-3 examinations do not apply to the CRGT split pins.

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Enclosure (b) As stated in NSPM letter dated March 7, 2013 (ML13067A284), CRGT Split Pins manufactured from 316 stainless steel (SS) have been classified as No Additional Measures components. For PINGP, this is justified by the performance of the improved design in fatigue life testing. During the qualification of the PINGP replacement upper internals, six 316 cold worked (CW) SS split pins of the new design were subject to fatigue testing in room temperature deionized water alongside the old style X-750 pins. Three radial directions of the applied cyclic lateral loading were examined in these tests. All of the X-750 pins failed in testing, whereas the tests were suspended before any failure of a 316 CW SS pin occurred.

Three additional tests were conducted at elevated temperatures (600-630 "F), also in deionized water, covering the same three lateral loading orientations as the room temperature tests. No failure was observed in any of the 316 CWSS specimens, which were subject to between 2 x10 6 and 4.8x10 6 cycles in the high temperature test. No wear was observed on the interfaces at the conclusion of testing, and no cracking resulted.

NRC RAI 2-4:

The NRC staff requests that the licensee address the following issues:

a. Pages 43-45 of Attachment 1 of the licensee's March 22, 2013, submittal includes the "Expansion Category" components. Clarify whether the "Expansion Link" column for that "Expansion Component" Table should be interpreted as a "Primary Link" column for the table.

b. Page 46 of Attachment 1 of the licensee's March 22, 2013, submittal includes the "Existing Program" components. Clarify whether the "Expansion Link" column for that "Existing Program Component" Table should be interpreted as an "Existing Program Reference" column for the table.

NSPM response:

a. Yes, the column heading for the "Expansion Component" table that was labeled "Expansion Link" in the March 22, 2013, submittal should have been labeled "Primary Link".

b. Yes, the column heading in the "Existing Program" components table that was labeled "Expansion Link" in the March 22, 2013, submittal should have been labeled "Existing Program Reference", and Note 1 should not apply.

Also, the column heading in the "Existing Program" components table that was labeled "Examination Method/Frequency (Note 1)" in the March 22, 2013, submittal should have been labeled only as "Examination Method" (Note 1 does not apply).

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