L-MT-16-026, Response to Request for Additional Information for Approval of Alternative to Apply the BWRVIP Guidelines in Lieu of Specific ASME Section XI Code Requirements for Reactor Pressure Vessel Internals and Components Inspection

Response to Request for Additional Information for Approval of Alternative to Apply the BWRVIP Guidelines in Lieu of Specific ASME Section XI Code Requirements for Reactor Pressure Vessel Internals and Components Inspection

ML16155A023
Person / Time
Site:	Monticello
Issue date:	06/02/2016
From:	Gardner P Northern States Power Co, Xcel Energy
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
CAC MF7111, L-MT-16-026
Download: ML16155A023 (18)

Text

(l Xcel Energy Monticello Nuclear Generating Plant 2807 W County Road 75 Monticello, MN 55362 June 2, 2016 L-MT-16-026 10 CFR 50.55a(z)(1)

U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Monticello Nuclear Generating Plant Docket No. 50-263 Renewed Facility Operating License No. DPR-22 Response to Request for Additional Information for Approval of an Alternative to Apply the BWRVIP Guidelines in Lieu of Specific ASME Section XI Code Requirements for Reactor Pressure Vessel Internals and Components Inspection (CAC No. MF7111)

References:

1) NSPM to NRC, "1 0 CFR 50.55a Request No. RR-01 0: Request for Approval of an Alternative to Apply the BWRVIP Guidelines in Lieu of Specific ASME Section XI Code Requirements for Reactor Pressure Vessel Internals and Components Inspection," (L-MT-15-083) dated November 20, 2015 (ADAMS Accession No. ML15324A305).

2) NRC e-mail to NSPM, "Draft Request for Additional Information RE:

Monticello, RR-01 0, Relief Request to Implement BWRVIP (CAC MF7111)," dated April 19, 2016.

On November 20, 2015, in accordance with 10 CFR 50.55a(z)(1), the Northern States Power Company- Minnesota (NSPM), doing business as Xcel Energy, Inc., submitted a 10 CFR 50.55a request (Reference 1) for application of an alternative to the requirements of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code. Specifically, it was requested to use the Boiling Water Reactor Vessel and Internals Project (BWRVIP) guidelines in lieu of specific ASME Section XI, "Rules for lnservice Inspection of Nuclear Power Plant Components," requirements for inspection of the Monticello Nuclear Generating Plant (MNGP) reactor vessel internals.

On April19, 2016, the U.S. Nuclear Regulatory Commission (NRC) requested additional information (RAI) from NSPM (Reference 2) to complete their review. The enclosure provides the requested information.

Summary of Commitments This letter proposes no new commitments and does not revise any existing commitments.

Document Control Desk L-MT-16-026 Page 2 of2 Should you have questions regarding this letter, please contact Mr. Richard Loeffler at (763) 295-1247.

Peter A. Gardner Site Vice President, Monticello Nuclear Generating Plant Northern States Power Company - Minnesota Enclosure cc: Administrator, Region Ill, USNRC Project Manager, Monticello, USNRC Resident Inspector, Monticello, USNRC Minnesota Department of Commerce

ENCLOSURE 1 MONTICELLO NUCLEAR GENERATING PLANT RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION REQUEST FOR APPROVAL OF AN ALTERNATIVE TO APPLY THE BWRVIP GUIDELINES IN LIEU OF SPECIFIC ASME SECTION XI CODE REQUIREMENTS FOR REACTOR PRESSURE VESSEL INTERNALS AND COMPONENTS INSPECTION (15 pages follow)

L-MT-16-026 Page 1 of 14 RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION REQUEST FOR APPROVAL OF AN ALTERNATIVE TO APPLY THE 8WRVIP GUIDELINES IN LIEU OF SPECIFIC ASME SECTION XI CODE REQUIREMENTS FOR REACTOR PRESSURE VESSEL INTERNALS AND COMPONENTS INSPECTION By letter dated November 20, 2015, in accordance with 10 CFR 50.55a(z)(1), the Northern States Power Company- Minnesota (NSPM), doing business as Xcel Energy, Inc., submitted a 10 CFR 50.55a request (Reference 1) for application of an alternative to the requirements of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code. Specifically, it was requested to use the Boiling Water Reactor Vessel and Internals Project (BWRVIP) guidelines in lieu of specific ASME Section XI, "Rules for lnservice Inspection of Nuclear Power Plant Components," requirements for inspection of the Monticello Nuclear Generating Plant (MNGP) reactor vessel internals.

RAI1 Table 1 of RR-01 0 compares the current ASME Code,Section XI examination category requirements with the current 8WRVIP guideline requirements, as applicable to the MNGP. However, the acceptance standards of the two were not compared in the table. For ASME Item No. 813.20, the required VT-1 examination method could detect crack-like surface flaws on the RVI components, and the ASME Code requires, as one of the options, an analytical evaluation be performed for these components if the detected surface crack exceeds the allowable linear flaw standards of IW8-3510. Regarding disposition of detected flaws:

1. identify the major differences in the flaw acceptance standard between the ASME Code. and the applicable 8WRVIP documents; and

2. discuss how RR-01 0 will change the disposition of detected flaws (using the 813.20 components as an example).

Response to Sub-Item 1 There are no major differences between flaw acceptance standards of Section XI of the ASME Code and the applicable BWRVIP documents, although, there are some differences in evaluation reporting requirements and flaw re-inspection requirements.

The ASME Code and BWRVIP both allow flaw acceptance by analytical evaluation.

All the components in Table 1 are B-N-1 and B-N-2 ASME components. Under Section XI of the ASME Code, B-N-1 and B-N-2 components containing relevant indications are evaluated in accordance with ASME Section XI IWB-3520.1, IWB-3520.2, and IWB-3430, as applicable. For B-N-1 and B-N-2 components, IWB-3520.1 and IWB-3520.2 require that actions to correct relevant conditions

L-MT-16-026 Page 2 of 14 meet the requirements of IWB-3142 prior to continued service. IWB-3142 allows acceptance of relevant indications by supplemental examination, corrective measures, repair/replacement activity or analytical evaluation. For analytical evaluation, IWB-3142.4 states:

A component containing relevant conditions is acceptable for continued service if an analytical evaluation demonstrates the component's acceptability.

The evaluation analysis and evaluation acceptance criteria shall be specified by the Owner. A component accepted for continued service based on analytical evaluation shall be subsequently examined in accordance with IWB-2420(b) and (c).

IWB-3430 specifies that the analytical evaluation of planar surface flaws meet the provisions of IWB-3600 for applicable materials.

Similar to Section XI of the ASME Code, the BWRVIP program allows flaws to be accepted by analytical evaluation. However, under the BWRVIP program, flaw evaluation analysis and evaluation acceptance criteria are specified by the BWRVIP rather than the Owner. The BWRVI P guidance requires that utilities evaluate inspection results according to the information contained in the latest revision of the applicable BWRVIP guidelines, and associated correspondence, as approved by the BWRVIP Executive Committee. The BWRVIP also requires that when new BWRVIP guidance approved by the Executive Committee includes changes to NRC approved BWRVIP guidance that are less conservative than those approved by the NRC, this less conservative guidance shall be implemented only after NRC approves the changes. The applicable BWRVIP technical guidance often invokes the use of ASME Section XI flaw evaluation techniques and acceptance criteria or references the applicable section of ASME Section XI for use in flaw evaluations.

Upon approval of this alternative, NSPM would use the applicable BWRVIP acceptance standard for flaw evaluations.

For example, BWRVIP-48-A, "BWR Vessel and Internals Project, VesseiiD Attachment Weld Inspection and Flaw Evaluation Guidelines," (Reference 2) and BWRVIP-38, "BWR Vessel and Internals Project, BWR Shroud Support Inspection and Flaw Evaluation Guidelines," (Reference 3) are the applicable BWRVIP documents for inspection and evaluation of 813.20 and 813.30 ASME Section XI components as indicated in Table 1 of the alternative request. BWRVIP-48-A requires flaw evaluations to be performed in accordance with ASME Section XI as described later, herein (see RAI-1 Sub-Item 2).

For components under BWRVIP-38, the flaw evaluation invokes use of ASME Section XI structural margins for flaw evaluation acceptance criteria,Section XI flaw proximity rules, and use of Section XI IWB-3600 for the applicable materials.

BWRVIP-38 also notes that the generic flaw evaluations, which are also to be used to perform detailed plant specific evaluations, provide flaw tolerance estimates for

L-MT 026 Page 3 of 14 each of the shroud support configurations in accordance with ASME Section XI requirements.

There-inspection requirements for ASME Section XI and the BWRVIP are somewhat different, but both require re-inspection of components accepted by evaluation. ASME Section XIIWB-3142.4 states that components accepted by evaluation must be inspected in accordance with IWB-2420(b) and (c).

IWB-2420(b) and (c) state:

(b) If a component is accepted for continued service in accordance with IWB-3132.3 or IWB-3142.4, the areas containing flaws or relevant conditions shall be reexamined during the next three inspection periods listed in the schedule of the Inspection Program of IWB-2400. Alternatively, acoustic emission may be used to monitor growth of existing flaws in accordance with IWA-2234.

(c) If the reexaminations required by IWB-2420(b) reveal that the flaws or relevant conditions remain essentially unchanged for three successive inspection periods, the component examination schedule may revert to the original schedule of successive inspections.

In accordance with the MNGP site procedures for the BWRVIP, relevant indications are re-inspected in accordance with the inspection schedule of the component or the interval specified in the flaw evaluation, whichever is shorter. For example, if a flawed component evaluation states that the component is acceptable by evaluation for 6 years and the component requires inspection every 10 years, the component and relevant indication would be reinspected every 6 years.

As previously noted, there are differences between ASME Section XI and the BWRVIP for evaluations that require submittal to the NRC. ASME Section XI IWB-3144 states:

Evaluation analyses of examination results as required by IWB-3142.4 shall be submitted to the regulatory authority having jurisdiction at the plant site.

As such, for ASME Section XI exams that accept flaws in components for continued service by analytical evaluation, NSPM is required to submit the evaluations to the NRC.

The BWRVIP guidance differs from this ASME Section XI requirement since the BWRVIP evaluations of in-scope components are submitted to the NRC only if the evaluation deviates from the BWRVIP technical guidance. Flaw evaluations may also be submitted to BWRVIP if required by the applicable BWRVIP guidelines. In both cases, however, evaluation results are available to the regulatory authority for information. Upon approval of this alternative request, NSPM would submit evaluations in accordance with BWRVIP guidance and continue to make the

L-MT-16-026 Page 4 of 14 evaluation results available for information to the regulatory authority, that being the NRC.

Response to Sub-Item 2 (request repeated here for convenience) discuss how RR-010 will change the disposition of detected flaws (using the 813.20 components as an example).

Upon approval of this alternative, flaws detected on ASME Section XI 8-N-1 and 8-N-2 components will be evaluated in accordance with the applicable 8WRVIP flaw evaluation guidelines. For example, ASME Section XI 813.20, components will be inspected and relevant indications evaluated applying 8WRVIP-48-A. Flaws identified in 813.20 components will be dispositioned in accordance Section 3.3 of 8WRVIP-48-A which states:

For any of the bracket attachment inspection flaw indications, the defect can be dispositioned based on the following:

• The inspection acceptance criteria specified in IW8-3520 of ASME XI for examination category 8-N-2, or

• A structural evaluation and determination of the suitability of the bracket attachment for continued plant operation following the approach described in Section 4.3 of this report Section 4.3 of 8WRVIP-48-A requires that relevant indications must either satisfy the criteria in ASME Section XI IW8-351 0, or apply IW8-3520.1, IW8-3142 and IW8-3600 to evaluate the indications, where applicable. If the components were to remain managed under the ASME Section XI, any relevant indications would have to satisfy the criteria under IW8-351 0 or use IW8.3520.1, IW8-3142 and IW8-3600 to evaluate the indications. In the case of ASME Section XI 813.20 components, the BWRVIP guidance is identical to the ASME Section XI requirements. Upon approval of this alternative, the flaw evaluation process for the 813.20 components does not change since the 8WRVIP-48-A flaw evaluation requirements invoke the use of ASME Section XI flaw evaluation requirements.

RAI2

1. The application references the 8WR Vessel and Internals Inspection Summaries for Spring 2013 Outages dated April11, 2014 (ADAMS Accession No. ML14125A303). The NRC staff reviewed this report and noted that although Table 1 of RR-01 0 showed both the ASME examination requirements and the alternative 8WRVIP examination requirements for the ASME Code Item 813.10, "Reactor Vessel Interior," the April11, 2014, report showed no inspection record for this item. Given that the most recent outage

L-MT-16-026 Page 5 of 14 report did not contain these inspection results, describe if or how RR-01 0 will change the recording and reporting of RVI inspection results.

The spring 2013 Refueling Outage (RFO) was the first of two outages in Period 1 of the 5tn lSI Interval, and no B-N-1 examinations were scheduled or performed during the refueling outage. Therefore, no examination results were available for inclusion.

During the second outage in Period 1 (2015 RFO), B-N-1 category examinations were performed concurrently with examinations on the core shroud support plate between jet pump assemblies, including the access hole cover regions. Only one condition, a small, round "BB size" piece of foreign material (weld slag, or spatter) that had settled on the shroud support plate near Jet Pump 01 (JP01) was identified and removed using a vacuum. No other B-N-1 conditions were identified.

As discussed in Section E.1 of the proposed alternative, conditions on reactor vessel internal components are reported under the BWRVIP reporting process (described in Section E.2), including deviations from BWRVIP guidelines. The format of the current BWRVIP Vessel Internals Inspection Summaries report, include the component, date, inspection method, a summarized description of the component or area, results, corrective actions, or special notations, as needed, and will not be changed.

Approval of this alternative will change how NSPM reports acceptance of vessel internal components requiring analytical analysis to demonstrate acceptable continued service. ASME Section XI IWB-3144(b) requires submittal of these evaluations to the regulatory authority, i.e., the NRC, for review. ASME Section XI Code Case N-532-5, "Repair I Replacement Activity Documentation Requirements and lnservice Inspection Summary Report Preparation and Submission,Section XI, Division 1,"(Reference 4), reports these items in Table 1 of the Owner's Activity Report (OAR-1) that is submitted to the NRC.

Under the BWRVIP reporting process, analytical evaluations performed in accordance with the BWRVIP Inspection and Evaluation Guidelines are not submitted to the NRC, and as the alternative to ASME Section XI for reporting, they will not be included in the OAR-1, Table 1. The analytical evaluations will, however, be provided to the Authorized Nuclear lnservice Inspector (ANI I). If an evaluation deviates from the BWRVIP guidance (e.g., the assumptions, methods, acceptance criteria, etc.), these analyses, including any subsequent revisions, are submitted to the NRC and BWRVIP, as well as the ANII.

L-MT-16-026 Page 6 of 14

2. The April11, 2014, inspection summaries indicate that flaws were detected in the core shroud, shroud support, core spray piping, and jet pump assembly.

For the NRC staff to determine the adequacy of applying the BWRVIP for these detected flaws:

(a) provide a brief discussion of evaluation of the worst detected flaw (the one with the least margin) in each of the four components.

(b) identify whether any of the flawed components are ASME Code components but were inspected and evaluated in accordance with the BWRVIP reports. If such components exist and the BWRVIP report inspection and evaluation methodologies for them are more relaxed than the corresponding ASME Code,Section XI methodologies, confirm whether requests for alternative were submitted for prior lSI intervals.

(c) confirm that a plant-specific leakage assessment was performed, as required by BWRVIP-18 (core spray), BWRVIP-41 (jet pump assembly),

and BWRVIP-76 (core shroud) or the ASME Code,Section XI for operability. If confirmed, provide a discussion of the margin between the calculated leakage and the allowable leakage based on adequate core cooling to maintain peak clad temperature within allowed limits during postulated loss of coolant accidents. If not confirmed, provide justification for not performing the required leakage assessment.

Response to Sub-Item (a) (request repeated here for convenience)

(a) provide a brief discussion of evaluation of the worst detected flaw (the one with the least margin) in each of the four components.

Core Shroud NSPM performed inspection of the core shroud using VT-3 in accordance with the requirements of ASME Section XI and no indications were identified. NSPM also performed inspection of the core shroud using UT in RF027 (20 15) in accordance with the requirements of the BWRVIP program. The UT inspection identified indications in core shroud horizontal welds, H1 through H6 and core shroud vertical welds V2 and V3. The MNGP core shroud indications were evaluated using the methodology outlined in BWRVIP-76 R1-A, "BWR Vessel and Internals Project, BWR Core Shroud Inspection and Flaw Evaluation Guidelines," (Reference 5).

BWRVIP-76 R1-A provides generic plant acceptance criteria and guidance for performance of plant specific evaluation for welds where the remaining ligament configuration and/or fluence exceeds the assumptions in the generic plant acceptance criteria. Those welds that require plant-specific analysis are more limiting than those welds that were accepted under the generic acceptance criteria

L-MT-16-026 Page 7 of 14 either by percentage of the inspected weld found flawed, weld fluence, inspection coverage or a combination of all three factors. Core shroud flaw evaluations determine whether the given ligament configuration for each core shroud weld satisfies the plant structural safety margins rather than evaluating each flaw on the core shroud individually. Welds requiring plant specific analysis are evaluated using one or more of three methodologies, listed in BWRVIP-76-R1-A; limit load, linear elastic fracture mechanics (LEFM) and elastic plastic fracture mechanics (EPFM).

The methodologies are similar to those described in ASME Section XI Appendix C.

The core shroud plant specific evaluations identify the required structural margin for normal/upset (Service Level NB) and emergency/faulted (Service Level C/D) conditions for each weld in the form of a minimum safety margin for limit load and LEFM, allowable crack length for limit load and maximum applied tearing modulus (Tapp) for EPFM. The results of the evaluation for each weld requiring plant-specific evaluation are shown below in Tables A, 8, C.

l T a bl e AS ummary 0 f L"1m11ng Sh rou d Honzon . ta I W e ld Eva Iuaf 1on Resu Its Service Level AlB Service Level C/D Evaluation Shroud Weld Acceptance Acceptance Method Results Results Criteria Criteria Limit Load SF=51.18 SF> 2.77 SF= 27.87 SF>1.39 H1 EPFM N/A N/A N/A N/A Limit Load SF= 36.28 SF> 2.77 SF= 19.78 SF>1.39 H3 EPFM Tapp = 0.112 Tapp <59 Tapp = 0.092 Tapp < 71 Limit Load SF= 34.19 SF> 2.77 SF= 18.31 SF> 1.39 H4 EPFM Tapp = 0.141 Tapp<30 Tapp = 0.123 Tapp <32 T a bl e B S ummary of Sh rou d Ve rf1caI W e ld L.1m1"t Loa dEva Iuaf 1on Resu Its Service Level AlB Service Level C/D Evaluation Shroud Weld Bounding Crack Allowable Bounding Crack Allowable Method Size Crack Length Size Crack Length V3 Limit Load 20.17 in. 85.24 in. 20.17 in. 84.59 in.

V4 Limit Load 20.17 in. 85.24 in. 20.17 in. 84.59 in.

Ta bl e C S ummary of Sh rou d V ert1ca . I W e ld s LEFM Eva Iuat1on Resu ts Service Level AlB Service Level C/D Allowable Evaluation Calculated Allowable Calculated Shroud Weld Stress Method Stress Intensity Stress Intensity Stress Intensity Intensity Factor Factor Factor Factor V3 LEFM 22.40 ksi-in°* 5 . 112.0 ksi-in°* 5 27.49 ksi-in°* 5 112.0 ksi-in°* 5 .

V4 LEFM 22.40 ksi-in°* 5 . 112.0 ksi-in°* 5 . 27.49 ksi-in°* 5 112.0 ksi-in°* 5 .

As shown in the tables above, the evaluation process differs between vertical and horizontal welds in accordance with BWRVIP-76 R1-A. Qualitatively, the H4 weld also has the deepest flaw that extends through half of the shroud thickness (0.88

L-MT-16-026 Page 8 of 14 inches deep or 50% through-wall). For the vertical welds, V3 and V4 both have identical structural margin based on the flaw evaluation results. For all the core shroud welds, the structural margin is acceptable for at least 10 years in accordance with BWRVIP-76 R1-A.

Shroud Support NSPM has inspected all accessible areas of the H8 and H9 welds from both the topside and the underside of the shroud support plate. All locations on the underside of the H8 and H9 welds that were inspected contained indications. No indications have been identified on the topside of the H8 and H9 welds. NSPM has inspected all fourteen shroud support leg H1 0 welds. All fourteen shroud support leg H10 welds contain indications. The flaws in the H8, H9 and H10 welds are considered to be the worst detected flaws in the shroud support structure based on bounding crack profiles assumed for the respective structural evaluations. Two bounding crack profiles were assumed for the H8 and H9 welds in order to evaluate the indications. For crack profile 1, the evaluation demonstrates that 87% of the H8 and H9 welds can be completely cracked through-wall, and the remaining 13% can be assumed to be cracked 2/3 of the way through wall, and the ASME Code requirement for structural margin (SF=1.4) is still met. For crack profile 2, the H8 and H9 welds are assumed to be cracked 100% circumferentially and 75% through-wall and the welds still meet the ASME Code requirement for structural margin.

There is no evidence of through-wall cracking on the H8 and H9 welds based on the visual inspection of both the topside and bottom side of the welds. The flaws in the H8 and H9 welds are not expected to propagate through more than approximately 66% of the weld material due to the compressive weld residual stress (WRS) distribution, the favorable water chemistry conditions and the negligible contribution of fatigue crack growth. Since there is no evidence of through-wall cracking and the flaws are not expected to propagate more than 66% through-wall, both crack profile cases are bounding of the current known condition of the H8 and H9 welds. The evaluation of the H8 and H9 welds remain acceptable provided that the condition of the H8 and H9 welds remain bounded by the assumed crack profiles in the evaluation.

Similar to the H8 and H9 welds, the H 10 weld indications were evaluated using a bounding crack profile. The bounding crack profile assumes that all of the H 10 welds are cracked to 31.2% of the weld length and demonstrates that the calculated structural safety margin meets the ASME Code required structural safety margin.

There is no evidence that any of the welds have reached 31.2% of the weld length for any of the H1 0 welds based on visual inspection indicating the evaluation assumption significantly bounds the weld condition. The evaluation of the H10 welds remains acceptable provided the condition of the H1 0 welds remain bounded by the assumed crack profile in the evaluation.

L-MT-16-026 Page 9 of 14 Table D provides a summary of the calculated structural safety margin and the required structural safety margin for the H8, H9 and H1 0 welds.

Ta bl e D S ummaryofSh rou d S up port W e ld Fl aw Eva Iuaf 1on Resuts Service Level AlB Service Level C/D Shroud Allowable Calculated Allowable Evaluation Calculated Support Structural Structural Structural Method Structural Weld Safety Safety Safety Safety Margin Margin Margin Margin H8/H9 (Crack Limit Load 17.38 2.4 1.48 1.4 Profile 1)

H8/H9 (Crack Limit Load 58.03 2.4 4.93 1.4 Profile 2)

H10 Limit Load 6.13 2.4 1.40 1.4 The above summary demonstrates that adequate structural safety margin exists for all shroud support welds.

Core Spray Piping The MNGP has one flaw in the core spray piping system. Other indications discovered early in plant life in the core spray piping have since been dispositioned as fabrication induced weld anomalies and are no longer tracked by the program as relevant indications. The one flaw is located in the P3A weld which is a core spray piping tee-box to piping weld on the "A" downcomer at the 90 degree vessel azimuth location. This flaw was originally identified in 1993. In 1994, NSPM installed mechanical clamps at the core spray tee-box location to ensure the structural integrity of the tee-box to piping welds. Both the P3A weld flaw and the repair clamp are inspected every outage to validate structural integrity.

Jet Pumps All MNGP jet pump indications are either in adjusting set screw tack welds, beam bolt retainer tack welds or on the jet pump secondary riser braces. All set screw tack welds and beam bolt retainer tack welds were either repaired and/or dispositioned as having no safety or structural impact. The MNGP jet pumps have two sets of riser braces, a primary and a secondary riser brace. The secondary riser braces, including any indications, are not required and will not affect the operation of the jet pumps.

L-MT-16-026 Page 10 of 14 Response to Sub-Item (b) (request repeated here for convenience)

(b) identify whether any of the flawed components are ASME Code components but were inspected and evaluated in accordance with the BWRVIP reports. If such components exist and the BWRVIP report inspection and evaluation methodologies for them are more relaxed than the corresponding ASME Code,Section XI methodologies, confirm whether requests for alternative were submitted for prior lSI intervals.

The components that are included in the ASME Section XI program as B-N-1 and B-N-2 components are listed in Table 1 of the request for an alternative, RR-01 0.

Additional line-items are proposed to be added to Table 1 and are provided in Table 1a, that is included as Attachment 1 to this enclosure. NSPM currently performs inspections and evaluations of these components at the MNGP in accordance with both the applicable ASME Section XI and BWRVIP requirements, therefore no alternative under 10 CFR 50.55a(z)(1) has been previously necessary.

Response to Sub-Item (c) (request repeated here for convenience)

(c) confirm that a plant-specific leakage assessment was performed, as required by BWRVIP-18 (core spray), BWRVIP-41 (jet pump assembly), and BWRVIP-76 (core shroud) or the ASME Code,Section XI for operability. If confirmed, provide a discussion of the margin between the calculated leakage and the allowable leakage based on adequate core cooling to maintain peak clad temperature within allowed limits during postulated loss of coolant accidents. If not confirmed, provide justification for not performing the required leakage assessment.

No leakage assessment is necessary for the MNGP jet pumps because none of the indications in the jet pump components are part of the pressure boundary of the jet pumps and no leakage pathway exist for loss of flow.

NSPM has not observed through-wall flaws in the core shroud. The deepest flaw in the MNGP shroud is 0.88 inches deep which is 50% through-wall. In accordance with BWRVIP-76 R1-A, leakage from cracking must be considered only when through-wall cracking is observed by inspection. No leakage assessment of the indications in the core shroud welds is required.

A plant specific leakage assessment was performed for the crack in the P3A weld in the core spray piping system in accordance with BWRVIP-18 R1-A. The total leakage from core spray piping flaws, including the consideration for hidden weld leakage is 25.6 gpm. The total assumed leakage for the core spray piping system is 108.8 gpm which includes leakage from core spray vent holes and the core spray tee-box repair. The core spray piping system has 12.2 gpm of remaining margin to

L-MT-16-026 Page 11 of 14 support adequate core cooling to maintain peak clad temperature within allowed limits during postulated loss of core cooling accidents.

RAI-3

RR-01 0 states under Section E, Footnote 4, "The inspection guidance of BWRVIP-25: BWR Core Plate Inspection and Flaw Evaluation Guidelines, is not applicable since in Reference 2, NUREG-1865 (Safety Evaluation Report for the MNGP license renewal), Section 4.8, "Stress Relaxation of Rim Holddown Bolts," an analysis was approved for MNGP. However, BWRVIP-25 is included for potential, future applicability."

Contrary to the information in Footnote 4, the approval of the MNGP plant-specific analysis for the rim holddown bolts in NUREG-1865 has simply resolved a major action item in the September 6, 2000, SE for BWRVIP-25 and, because of this, NSPM can apply BWRVIP-25 to MNGP. To not perform the required inspections on the core plate under ASME Section XI, Examination Category B-N-2, "Integrally Welded Core Support Structures," MNGP needs to apply BWRVIP-25 in the 5th lSI interval as an alternative, regardless of which option in BWRVIP-25 NSPM chooses to follow. Because the use of the analysis described in NUREG-1865 would require the application of BWRVIP-25, clarify if the subject components are covered by the requested relief or would be subject to the requirements of the ASME Code if the request relief were granted.

Response

The core plate is an ASME Code component and the accessible surfaces of the core plate are inspected under the ASME Section XI program for 8-N-2/813.40 when the fuel cells are vacated. NSPM has performed the inspections required by ASME Section XI to date.

This request for an alternative, RR-01 0, should also have specified 8WRVIP-25, "8WR Vessel and Internals Project, 8WR Core Plate Inspection and Flaw Evaluation Guidelines," (Reference 6), within Table 1. A line-item for 8WRVIP-25 is proposed to be added to Table 1. This new line-item is provided in Table 1a, included as to this enclosure. An analysis and evaluation similar to the guidance of 8WRVIP-25, Appendix A, was performed on the MNGP core plate hold-down bolts.

This analysis provided the basis for not performing the inspections required in 8WRVIP-25 and was accepted by the NRC in NUREG-1865, "Safety Evaluation Report Related to the License Renewal of the Monticello Nuclear Generating Plant,"

(Reference 7). NSPM requests to include 8WRVIP-25 within the scope of this alternative request. Upon approval of this alternative, the core plate will be managed in accordance with 8WRVIP-25 and will continue to credit the evaluation in lieu of the inspections as described in NUREG-1865.

L-MT-16-026 Page 12 of 14

RAI-4

Regarding BWRVIP-41, Revision 3 and BWRVIP-47-A, RR-010 states under Section E, Footnote 5, "However, none of the components are B-N-1 or B-N-2 components as defined by ASME Section XI and are outside of the scope of this 10 CFR 50.55a(z)(1) request for an alternative." Consistent with your approach of not listing irrelevant BWRVIP reports (such as BWRVIP-42, Revision 1 and BWRVIP-139-A) in the list of Section E.1 of RR-010, please explain the inclusion of BWRVIP-41, Revision 3 and BWRVIP-47-A or consider deletion from the list to avoid confusion.

Further, Section 8 of BWRVIP-183 has a footnote, indicating that the examinations recommended by the guidelines in BWRVIP-183 do not supersede the requirements of the ASME Code. Please confirm that NSPM' s inspections of top guide beams in the future do not supersede the ASME Code requirements. As such, please explain the inclusion of BWRVIP-183 in the list of Section E.1 of RR-01 0 or consider deletion from the list. Ensure the footnotes related to the list of Section E.1 of RR-010 are updated as necessary.

Response

NSPM intended to include each of the guidelines for use with this proposed alternative request submitted as RR-01 0.

8WRVIP-41, Revision 3, "8WR Vessel and Internals Project, 8WR Jet Pump Assembly Inspection and Flaw Evaluation Guidelines," (Reference 8) and 8WRVIP-47-A, "8WR Vessel and Internals Project, 8WR Lower Plenum Inspection and Flaw Evaluation Guidelines," (Reference 9) are listed in Table 1 of the alternative request for ASME Item 813.10, and are applicable for providing overview exams during Jet Pump and Lower Plenum inspection activities as the alternative to 813.10 requirements. 8WRVIP-47-A is also provided as applicable to the Control Rod Guide Tubes (CRGTs). Further discussion of 8WRVIP-47-A for the CRGTs is provided below.

With regard to Footnote 5, NSPM would like to clarify that Footnote 5 was intended to describe the Cast Austenitic Stainless Steel (CASS) components that fall within the 8WRVIP-41, Revision 3 and 8WRVIP-47-A guidelines, which are the Jet Pump inlet elbow, diffuser collar, mixer flare, mixer flange, and riser transition piece in 8WRVIP-41, Revision 3 and the orificed fuel support in 8WRVIP-47-A.

A revised Footnote 5 to clarify the CASS components (see underlined below), and that supersedes the prior footnote, is provided below:

NUREG-1865 (Reference 2), Subsection 3.0.3.1.8, "Thermal Aging & Neutron Irradiation Embrittlement of Cast Austenitic Stainless Steel (CASS) Program,"

summarizes the inspection of MNGP CASS components. For the purpose of

L-MT-16-026 Page 13 of 14 condition monitoring the inspection schedule is managed in accordance with the guidance for B-N-1 and B-N-2 components under ASME Section XI. However, none of the CASS components are B-N-1 or B-N-2 components as defined by ASME Section XI and are outside of the scope of this 10 CFR 50.55a(z)(1) request for an alternative.

BWRVIP-183, "BWR Vessel and Internals Project, Top Guide Grid Beam Inspection and Flaw Evaluation Guidelines," (Reference 10), provides for examination of the Top Guide, namely the grid beams. Although BWRVIP-183 is used for inspection of the Top Guide for the BWRVIP program for MNGP, the Top Guide is not a specified component in the MNGP ASME XI lSI Program, therefore, the footnote in Section 8 of BWRVIP-183 is not applicable for MNGP.

In addition to BWRVIP program inspections performed per BWRVIP-183, inspections of the Top Guide assembly are also performed under BWRVIP-26-A, "BWR Vessel and Internals Project, BWR Top Guide Inspection and Flaw Evaluation Guidelines,"

(Reference 11 ). BWRVIP-26-A was included in Section E.1 and Table 1 of the alternative request, as one of the proposed BWRVIP guidance documents that will provide overview exams as an alternative for Item No. B13.1 0. Because BWRVIP program inspections performed on the Top Guide components for BWRVIP-183 can provide information similar to BWRVIP-26-A that was proposed as an alternative for Item No. B 13.1 0, NSPM intends to keep BWRVI P-183 in the list of applicable referenced BWRVIP guidelines in Section E.1 of RR-01 0, and proposes to add the guideline to Table 1 as an alternative guideline applicable for Item No. B 13.10 exam.

As part of this RAI response, NSPM is supplementing Table 1 of the alternative request with a line-item adding BWRVIP-183 to the table under ASME Item No. B13.10. This new line-item is provided in Table 1a, included as Attachment 1 to this enclosure.

During review of RAI-4, NSPM determined that additional information should be provided in Table 1 of the alternative request for ASME Item B13.40 and the applicability of BWRVIP-47-A. NSPM includes the CRGTs in the 5th Interval lSI Plan as welded core support structures for examination under ASME Item B13.40, if they become accessible when a fuel cell is vacated. The guideline was included in Section E.1 of the alternative request but an entry was not included for the CRGTs under ASME Item No. B13.40 in Table 1 of the request. NSPM is supplementing Table 1 with a line-item adding BWRVIP-47-A to the table under ASME Item No. B13.40 for CRGTs. This new line-item is provided in Table 1a, included as Attachment 1 to this enclosure.

L-MT-16-026 Page 14 of 14 REFERENCES

1. Letter from NSPM to NRC, "1 0 CFR 50.55a Request No. RR-01 0: Request for Approval of an Alternative to Apply the BWRVIP Guidelines in Lieu of Specific ASME Section XI Code Requirements for Reactor Pressure Vessel Internals and Components Inspection," (L-MT-15-083), dated November 20, 2015

2. BWRVIP-48-A: "BWR Vessel and Internals Project, VesseiiD Attachment Weld Inspection and Flaw Evaluation Guidelines," dated June 2004

3. BWRVIP-38: "BWR Vessel and Internals Project, BWR Shroud Support Inspection and Flaw Evaluation Guidelines," dated September 1997

4. ASME Section XI Code Case N-532-5, "Repair I Replacement Activity Documentation Requirements and lnservice Inspection Summary Report Preparation and Submission Section XI, Division 1,"dated January 4, 2011

5. BWRVIP-76, Revision 1-A: "BWR Vessel and Internals Project, BWR Core Shroud Inspection and Flaw Evaluation Guidelines," dated April 2015

6. BWRVIP-25: "BWR Vessel and Internals Project, BWR Core Plate Inspection and Flaw Evaluation Guidelines," dated December 1996

7. NUREG-1865, "Safety Evaluation Report Related to the License Renewal of the Monticello Nuclear Generating Plant," dated October 2006

8. BWRVIP-41, Revision 3, "BWR Vessel and Internals Project, BWR Jet Pump Assembly Inspection and Flaw Evaluation Guidelines," dated September 2010

9. BWRVIP-47-A: "BWR Vessel and Internals Project, BWR Lower Plenum Inspection and Flaw Evaluation Guidelines," dated June 2004

10. BWRVIP-183: "BWR Vessel and Internals Project, Top Guide Grid Beam Inspection and Flaw Evaluation Guidelines," dated December 2007

11. BWRVIP-26-A: "BWR Vessel and Internals Project, BWR Top Guide Inspection and Flaw Evaluation Guidelines," dated November 2004

L-MT-16-026 Enclosure 1 Attachment 1 Page 1 of 1 TABLE 1a: MNGP Comparison of ASME Examination Categor~ 8-N-1 and 8-N-2 Requirements With BWRVIP Guidance Requirements Note 1)

ASME Examination Requirements BWRVIP Examination Requirements Component ASME Item ASME ASME Applicable ASME BWRVIP Exam BWRVIP BWRVIP No. (Table Exam Exam BWRVIP Frequency Scope Exam Frequency IWB 2500-1) Scope Type Document Reactor Vessel Interior B13.10 Accessible VT-3 Each Period BWRVIP-183 Overview examination of components during areas in a 10-Year BWRVIP examinations meets the intent of the Interval Code VT-3 inspection requirements.

Welded Core Support B13.40 Accessible VT-3 Each BWRVIP-25 Rim Hold-down Bolts UT or See Structure - Core Plate surfaces 10-Year Section 3.2.2 EVT-1 Note 6.

(when accessible, fuel Interval Table 3-2 cells vacated)

Welded Core Support B13.40 Accessible VT-3 Each BWRVIP-47-A CRGT-1, Sleeve to VT-3 10% in the Structure - Control surfaces 10-Year Section 3.2.2 alignment lug weld first Rod Guide Tubes Interval Table 3-3 CRGT-2 Body to EVT-1 12-years (CRGTs), Interior Sleeve Weld, with 5%

(when accessible, fuel CRGT-3 Base to min. in first cells vacated) Body Weld 6 years FS/GT-APRIN-1 VT-3 Guide Tube and Fuel Support Alignment Pin-to-Core Plate Weld, and Pin Itself NOTES ([Notes 1 through 5 occur in Table 1. To align with this table being appended to Table 1 included in the alternative request, Note 6 is the next available number.)

1. This Table provides only an overview of the requirements. For more details, refer to ASME Section XI, Table IWB-2500-1, and the appropriate BWRVIP document.

6. An analysis performed for License Renewal (see NUREG-1865) provided an alternative to the inspection requirements of BWRVIP-25.