RS-20-095, Response to Request for Additional Information Related to Relief Request I4R-06 for the Fourth Inservice Inspection Interval

Response to Request for Additional Information Related to Relief Request I4R-06 for the Fourth Inservice Inspection Interval

ML20226A449
Person / Time
Site:	Clinton
Issue date:	08/13/2020
From:	Simpson P Exelon Generation Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
RS-20-095
Download: ML20226A449 (24)

Text

4300 Winfield Road Warrenville, IL 60555 630 657 2000 Office RS-20-095 10 CFR 50.55a August 13, 2020 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Clinton Power Station, Unit 1 Facility Operating License No. NPF-62 NRC Docket No. 50-461

Subject:

Response to Request for Additional Information Related to Relief Request I4R-06 for the Fourth Inservice Inspection Interval

References:

1. Letter from D. M. Gullott (Exelon Generation Company, LLC) to U.S. NRC, "Relief Requests Associated with the Fourth Inservice Inspection Interval,"

dated December 16, 2019

2. Email from J. Wiebe (U.S. NRC) to K. M. Nicely (Exelon Generation Company, LLC), "Preliminary RAIs Regarding Clinton RR I4R-06," dated July 14, 2020 In Reference 1, in accordance with 10 CFR 50.55a, "Codes and standards," paragraph (z)(1),

Exelon Generation Company, LLC (EGC) requested NRC approval of the several relief requests associated with the fourth Inservice Inspection (ISI) interval for Clinton Power Station (CPS),

Unit 1. One of the relief requests (i.e., Relief Request I4R-06) requested approval to implement alternative BWRVIP Guidelines in lieu of ASME Code Section XI Table IWB-2500-1 Examination Category B-N-1 and B-N-2 requirements.

In Reference 2, the NRC requested additional information that is needed to complete review of Relief Request I4R-06, "Alternative for the Use of the BWRVIP Guidelines in Lieu of Specific ASME Code Requirements on Reactor Pressure Vessel Internals and Components Inspection."

In response to this request, EGC is providing the attached information.

August 13, 2020 U.S. Nuclear Regulatory Commission Page 2 There are no regulatory commitments contained within this letter. Should you have any questions concerning this letter, please contact Mr. Kenneth M. Nicely at (630) 657-2803.

Respectfully, Patrick R. Simpson Sr. Manager Licensing Attachments:

1. Response to Request for Additional Information Regarding Relief Request I4R-06

2. 10 CFR 50.55a Relief Request I4R-06, Revision 1 cc:

NRC Regional Administrator, Region III NRC Senior Resident Inspector - Clinton Power Station

ATTACHMENT 1 Response to Request for Additional Information Regarding Relief Request I4R-06 Page 1 NRC Request 1 10 CFR 50.55a(g)(4) requires inservice inspection of ASME Code Class 1 components to be performed in accordance with Section XI of the ASME Code. The licensee has proposed an alternative to the inspection requirements of Section XI for ASME Code Class 1, Examination Category B-N-1 and B-N-2 components. Specifically, the licensee proposed that accessible surfaces of shroud support legs be examined with the appropriate method in accordance with the Boiling Water Reactor Vessel and Internals Program (BWRVIP) Topical Report BWRVIP-38, Section 3.2.3 (proprietary) and the NRC staff's SE of BWRVIP-38 dated July 24, 2000 (BWRVIP-38 SE, ADAMS Accession No. ML003735498). The licensee also proposes that the lower plenum inspection be performed in accordance with BWRVIP Topical Report BWRVIP-47-A (proprietary), which was approved by NRC letter dated September 1, 2005 (ADAMS Accession No. ML052490537).

RAI 1a Issue 3.1.2 in the BWRVIP-38 SE states that the BWRVIP considers that inspection of shroud support legs to be unnecessary, while the NRC staff considers that an appropriate re-inspection schedule, based on appropriate safety considerations, should be established by the BWRVIP in a revised BWRVIP-38 report. The NRC staff concluded in the BWRVIP-38 SE that this issue is open and that the BWRVIP should provide the proposed revised inspection guidance, with appropriate scope expansion criteria and a re-inspection schedule, to the staff in a timely manner.

Since the licensee proposed alternative makes reference to an SE with an open item, and the BWRVIP has not yet provided revised inspection guidance, the NRC staff requests that the licensee discuss the following, related to the inspection of the shroud support welds (defined as those welds below H9, such as weld H12):

Are inspections of the shroud support leg welds planned at Clinton during the 4th ISI interval?

Will the shroud support leg welds at Clinton be accessible for inspection during the 4th ISI interval?

If inspections are not planned and the shroud support leg welds are accessible, provide a technical basis describing how the structural integrity of the core shroud will be maintained regarding potential degradation due to intergranular stress corrosion cracking (IGSCC).

RAI 1b Section 3.2.4 in BWRVIP-47-A states that no additional inspections are recommended beyond the baseline inspections, and scope expansion and follow-on inspections deemed necessary in the event flaws are found. Section 3.2.4 in BWRVIP-47-A also states, in part, that baseline inspection results will be reviewed by the BWRVIP and, if deemed necessary, reinspection recommendations will be developed at a later date and provided to the NRC. The NRC staff concluded in the Final Safety Evaluation (BWRVIP-47-A, Appendix C, Section 2.3) that the

ATTACHMENT 1 Response to Request for Additional Information Regarding Relief Request I4R-06 Page 2 "BWRVIP committed to address the issue of reinspection in the future after initial baseline inspections have been completed by a majority of U.S. BWRs. The staff accepted this commitment."

Since the licensee proposed alternative makes reference to an SE with an unresolved commitment, and the BWRVIP has not yet provided revised inspection guidance, the NRC staff requests that the licensee discuss the following, related to the inspection of the lower plenum components:

Are inspections of the lower plenum components planned at Clinton during the 4th ISI interval?

Will the lower plenum components at Clinton be accessible for inspection during the 4th ISI interval?

If inspections are not planned and lower plenum components are accessible, provide a technical basis describing how the integrity and function of the lower plenum supports will be maintained regarding potential degradation due to IGSCC.

Response

RAI 1a No inspections of the shroud support legs are planned at Clinton Power Station (CPS) during the fourth Inservice Inspection (ISI) interval. During a normal refueling outage, there is no access to the shroud support legs without removal of components such as control rod guide tubes or jet pump mixers. There are no activities currently planned that would allow for access to the lower plenum region and the shroud support legs during the fourth ISI interval at CPS.

Due to the accessibility limitations, BWRVIP-38 does not require periodic inspection of shroud support leg welds. However, if shroud support leg welds become accessible, examinations will be performed to the extent practical during that refueling outage.

RAI 1b No inspections of the lower plenum components are planned at CPS during the fourth ISI interval. During a normal refueling outage, there is no access to the lower plenum without removal of components such as control rod guide tubes or jet pump mixers. There are no activities planned that would allow for access in the lower plenum during the fourth ISI interval at CPS. However, if lower plenum welds become accessible, inspections will be performed to the extent practical during that refueling outage in accordance with BWRVIP-47-A Section 3.2.5.

NRC Request 2 10 CFR 50.55a(g)(4) requires inservice inspection of ASME Code Class 1 components to be performed in accordance with Section XI of the ASME Code. The licensee has proposed an alternative to the inspection requirements of Section XI for ASME Code Class 1, Examination

ATTACHMENT 1 Response to Request for Additional Information Regarding Relief Request I4R-06 Page 3 Category B-N-1 and B-N-2 components. Specifically, the licensee proposed that tie-rod shroud repairs be examined per repair designer recommendations in accordance with BWRVIP-76-R1-A, Section 3.5 (ADAMS Accession No. ML15266A189). However, BWRVIP-76-R1-A, Section 3.5 specifies two options for inspection of repair components after the first cycle:

Option 1: Perform a detailed inspection of all repair assemblies after the first cycle. If all assemblies are satisfactory, no inspections are required for 10 years.

Option 2: Perform a detailed inspection of 25% of the assemblies after the first cycle and a VT-3 of the other 75% of the assemblies. If the inspection results are satisfactory, detailed inspections of one-third of the remaining assemblies shall be performed during each of the next three outages. Re-inspect each assembly on a 10-year cycle.

Although the inspection summaries referenced in Table 1 of the proposed alternative suggest a modified version of Option 2 was adopted in the past, the proposed alternative does not specify what inspection frequency will be used going forward. Therefore, the NRC staff requests that the licensee describe the proposed inspection frequency of the tie-rod shroud repairs for the fourth ISI interval at Clinton.

Response

CPS has adopted the reinspection frequency of Option 2 from BWRVIP-76 Revision 1-A.

Therefore, each tie-rod assembly will be re-inspected every 10-year cycle. It should be noted that this 10-year cycle may not align with the 10-year ISI interval.

NRC Request 3 The licensee proposed alternative states that:

"Where guidance in existing BWRVIP documents has been supplemented or revised by subsequent correspondence approved by the BWRVIP Executive Committee, the vessel and internals program shall be modified to reflect the new requirements and implement the guidance within two refueling outages, unless a different schedule is specified by the BWRVIP. However, if approved BWRVIP inspection guidance approved by the Executive Committee includes changes to NRC approved BWRVIP inspection guidance that are less conservative than those approved by the NRC, the less conservative guidance shall be implemented only after the NRC approves the changes, which generally means publication of a '-A' document or equivalent.

Where the revised version of a BWRVIP inspection guideline continues to also meet the requirements of the version of the BWRVIP inspection guideline that forms the safety basis for the NRC-authorized proposed alternative to the requirements of 10 CFR 50.55a, it may be implemented. Otherwise, the revised guidelines will only be implemented after NRC approval of the revised BWRVIP guidelines or a plant-specific request for relief has been approved."

ATTACHMENT 1 Response to Request for Additional Information Regarding Relief Request I4R-06 Page 4 As stated in a meeting with Exelon on December 19, 2018 (ADAMS Accession No. ML18354B171), the NRC staff is unable to approve a licensee proposal that BWRVIP guidelines can be revised without a subsequent plant-specific request, because the licensee is requesting to use revisions of BWRVIP Topical Reports that NRC staff have not yet seen. The NRC staff determined that one acceptable resolution would be to remove the above two paragraphs from the proposed alternative request.

Response

The above two paragraphs have been removed from the proposed alternative request. The revised relief request is provided in Attachment 2.

NRC Request 4 BWRVIP-62-A, "Technical Basis for Inspection Relief for BWR Internal Components with Hydrogen Injection," and the included NRC staff SE (ADAMS Accession No. ML19178A130) accepted for use the noble metal chemical addition (NMCA) process and hydrogen water chemistry (HWC), moderate (HWC-M), as bases for claiming relief from certain BWRVIP inspections. As described in BWRVIP-62-A, NMCA is a process in which noble metal is added in batches to the reactor coolant system during refueling outages, and small amounts of hydrogen are continuously injected during plant operation. The NRC staff SE for BWRVIP-62-A, accepted for use three criteria that plants applying noble metal chemistry must meet to demonstrate mitigation of Intergranular stress corrosion cracking (IGSCC):

1) Measured electrochemical potential (ECP) less than or equal to -230 millivolts (mV).

2) Measured hydrogen-to-oxygen molar ratio greater than or equal to 3.

3) Measured catalyst loading greater than or equal to a specific proprietary value.

BWRVIP-62-A is referenced by other BWRVIP inspection and evaluation guidelines, and implementation of water chemistry in accordance with BWRVIP-62-A is credited to reduce the inspections identified in those documents.

By letter dated January 24, 2018, (Electric Power Research Institute - Status of BWRVIP-62 Revision and Inspection Relief for BWR Piping Welds and Internal Components with Hydrogen Injection, January 24, 2018 (ADAMS Accession No. ML18033A323)), the BWRVIP stated that the BWRVIP had issued the following interim guidance to its members:

U.S. plants utilizing all forms of HWC and crediting HWC shall meet the conditions and limitations of BWRVIP-62-A. In the case of plants utilizing OLNC [online noble metal chemistry], this means they shall meet the Category 3a NMCA parameters and implementation steps (including platinum loading) of Tables 3-5 and 3-8. This guidance is issued as NEI 03-08 'Needed' guidance.

Because OLNC is one method to introduce noble metal, plant-specific implementation of OLNC which demonstrates conformance with the performance criteria of BWRVIP-62-A can utilize the

ATTACHMENT 1 Response to Request for Additional Information Regarding Relief Request I4R-06 Page 5 inspection credit as specified in sources referencing BWRVIP-62-A, consistent with the BWRVIP interim guidance provided in its January 24, 2018, letter to the NRC.

The licensee submittal dated December 16, 2019 did not identify the method of chemical mitigation for IGSCC as described above. Since there is a correlation between the chemical mitigation program implemented and the inspection frequency specified by the BWRVIP alternative, staff requires additional information to complete its review.

1. Identify the type of chemical mitigation method that is being implemented at Clinton.

2. Identify how the conditions and limitations of BWRVIP-62-A are being met. If the chemical mitigation method is OLNC, in addition provide information specific to the Category 3A NMCA parameters and implementation steps as described in the safety evaluation to the 2018 supplement to the BWRVIP-62-A report (ADAMS Accession No. ML18142A019).

Response

1. CPS implements Online NobleChemTM (OLNC) injection and HWC to mitigate IGSCC.

CPS's initial OLNC application was in April 2014, and OLNC has been re-applied multiple times. CPS has been injecting hydrogen since 2002.

2. CPS meets the conditions and limitations of BWRVIP-62-A (2018 update). Details are provided below regarding how the conditions and limitations are met.

CPS primary parameters for HWC:

measured ECP catalyst loading CPS secondary parameters for HWC:

Feedwater hydrogen flow rate Feedwater hydrogen concentration reactor water oxygen concentration measured Hydrogen: Oxygen molar ratio Hydrogen: Oxygen molar ratio from Radiolysis Model ECP probes were installed on the Mitigation Monitoring System (MMS)/Durability Monitor and implemented in March 2014 with the initial application of OLNC.

The effectiveness of OLNC is dependent upon the hydrogen to oxygen molar ratio present at the locations of interest. Ratios > 2 are required to demonstrate the effectiveness of OLNC.

The hydrogen ramp/benchmark test was performed in June 2015 to determine the Feedwater hydrogen concentration to achieve a H2:O2 molar ratio of 2:1 or ECP of -230 mV(SHE). The Feedwater hydrogen benchmark value to achieve the 2:1 molar ratio was 0.084 ppm. During the ramp test, ECP was correlated with Feedwater concentration, Feedwater hydrogen flow rate, and reactor water oxygen concentration.

ATTACHMENT 1 Response to Request for Additional Information Regarding Relief Request I4R-06 Page 6 HWC and OLNC mitigate IGSCC when the ECP is reduced to protective levels. When ECP values are reduced below -230 mV(SHE) by the addition of excess hydrogen, the surfaces are considered mitigated against IGSCC. ECP readings are more negative than the threshold value of -230 mV(SHE) to provide additional margin for IGSCC mitigation.

June 2020 Cycle 20 Cycle 19 Avg ECP, mV(SHE)

-511

-510

-506

% HWC Availability 100%

99.2%

98.1%

CPS Unit 1 applies the EPRI Boiling Water Reactor Vessels and Internals Assessment (BWRVIA) model to determine the hydrogen injection rate required for a molar ratio >4 at the upper downcomer location for the beginning, middle, and end of the fuel cycle. CPS maintains a Feedwater hydrogen flowrate of 12.5 scfm to maintain a H2:O2 molar ratio >4.

Two durability coupons were removed in February 2020 following the OLNC application in January 2020. Both coupons had catalyst loadings greater than 0.1 g/cm2.

ATTACHMENT 2 10 CFR 50.55a Relief Request I4R-06, Revision 1 Alternative for the Use of the BWRVIP Guidelines in Lieu of Specific ASME Code Requirements on Reactor Pressure Vessel Internals and Components Inspection

10 CFR 50.55a Relief Request I4R-06 Alternative for the Use of the BWRVIP Guidelines in Lieu of Specific ASME Code Requirements on Reactor Pressure Vessel Internals and Components Inspection in Accordance with 10 CFR 50.55a(z)(1)

--Alternative Provides Acceptable Level of Quality and Safety--

Revision 1 (Page 1 of 10)

1.

ASME Code Component(s) Affected Code Class:

1

Reference:

IWB-2500, Table IWB-2500-1 Examination Category:

B-N-1 and B-N-2 Item Number:

B13.10, B13.20, B13.30, and B13.40

==

Description:==

Use of BWRVIP Guidelines in Lieu of Specific ASME Section XI Requirements on the Reactor Pressure Vessel Internals and Components Inspection Component Name:

Vessel Interior, Interior Attachments within Beltline Region, Interior Attachments beyond Beltline Region, and Core Support Structure

2.

Applicable Code Edition The Fourth Ten-Year Interval of the Clinton Power Station, Unit 1 (CPS) Inservice Inspection (ISI) Program is based on the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel (BPV) Code,Section XI, 2013 Edition.

3.

Applicable Code Requirement

ASME Section XI requires the examination of components within the reactor pressure vessel. These examinations are included in Table IWB-2500-1, Examination Categories B-N-1 and B-N-2 and identified with the following item numbers:

B13.10 Examine accessible areas of the reactor vessel interior each period by the VT-3 visual examination method (B-N-1).

B13.20 Examine interior attachment welds within the beltline region each interval by the VT-1 visual examination method (B-N-2).

B13.30 Examine interior attachment welds beyond the beltline region each interval by the VT-3 visual examination method (B-N-2).

B13.40 Examine accessible surfaces of the core support structure each interval by the VT-3 visual examination method (B-N-2).

These examinations are performed to assess the structural integrity of the reactor vessel interior, its welded attachments, and the core support structure within the boiling water reactor (BWR) pressure vessel.

The components/welds listed in Table 2 are subject to this request for alternative.

Table 2 provides only an overview of the requirements. For more details, refer to ASME Section XI, Table IWB-2500-1 and the appropriate Boiling Water Reactor Vessel and Internals Project (BWRVIP) document.

10 CFR 50.55a Relief Request I4R-06 Alternative for the Use of the BWRVIP Guidelines in Lieu of Specific ASME Code Requirements on Reactor Pressure Vessel Internals and Components Inspection in Accordance with 10 CFR 50.55a(z)(1)

--Alternative Provides Acceptable Level of Quality and Safety--

Revision 1 (Page 2 of 10)

4.

Reason for Request

In accordance with 10 CFR 50.55a(z)(1), relief is requested for the proposed alternative to ASME Section XI requirements provided above on the basis that the use of the BWRVIP guidelines discussed below will provide an acceptable level of quality and safety.

The BWRVIP Inspection and Evaluation (I&E) guidelines recommend specific inspections by BWR owners to identify material degradation with BWR components. A wealth of inspection data has been gathered during these inspections across the BWR industry. The BWRVIP guidelines focus on specific and susceptible components, specify appropriate inspection methods capable of identifying known or potential degradation mechanisms, and require re-examination at appropriate intervals. The scope of the BWRVIP guidelines meet or exceed that of ASME Section XI and in many instances include components that are not part of the ASME Section XI jurisdiction.

As an alternative to ASME Section XI requirements, use of BWRVIP guidelines will avoid duplicate or unnecessary inspections, while conserving radiological dose.

5.

Proposed Alternative and Basis for Use In lieu of the requirements of ASME Section XI, the proposed alternative is detailed in Table 2 for CPS for Examination Categories B-N-1 and B-N-2.

CPS will satisfy the Examination Category B-N-1 and B-N-2 requirements as described in Table 2 in accordance with the latest Nuclear Regulatory Commission (NRC) approved BWRVIP guideline requirements. This relief request proposes to utilize the identified BWRVIP guidelines in lieu of the associated ASME Section XI requirements, including the examination method, examination volume, frequency, training, successive and additional examinations, flaw evaluations, and reporting.

Not all the components addressed by these guidelines are ASME Section XI components. The following BWRVIP guidelines are applicable to this relief request:

o BWRVIP-03, "BWR Vessel and Internals Project, Reactor Pressure Vessel and Internals Examination Guidelines" o BWRVIP-18, Revision 2-A, "BWR Core Spray Internals Inspection and Flaw Evaluation Guidelines" o BWRVIP-26-A, "BWR Top Guide Inspection and Flaw Evaluation Guidelines" o BWRVIP-27-A, "BWR Standby Liquid Control System/Core Plate P Inspection and Flaw Evaluation Guidelines" o BWRVIP-38, "BWR Shroud Support Inspection and Flaw Evaluation Guidelines" o BWRVIP-41, Revision 4-A, "BWR Jet Pump Assembly Inspection and Flaw Evaluation Guidelines" o BWRVIP-42, Revision 1-A, "Low Pressure Coolant Injection System (LPCI)

Coupling Inspection and Flaw Evaluation Guidelines"

10 CFR 50.55a Relief Request I4R-06 Alternative for the Use of the BWRVIP Guidelines in Lieu of Specific ASME Code Requirements on Reactor Pressure Vessel Internals and Components Inspection in Accordance with 10 CFR 50.55a(z)(1)

--Alternative Provides Acceptable Level of Quality and Safety--

Revision 1 (Page 3 of 10) o BWRVIP-47-A, "BWR Lower Plenum Inspection and Flaw Evaluation Guidelines" o BWRVIP-48-A, "Vessel ID [Internal Diameter] Attachment Weld Inspection and Flaw Evaluation Guidelines" o BWRVIP-76, Revision 1-A, "BWR Core Shroud Inspection and Flaw Evaluation Guidelines" o BWRVIP-94, "BWR Vessel and Internals Project, Program Implementation Guide" o BWRVIP-138, Revision 1-A, "Updated Jet Pump Beam Inspection and Flaw Evaluation Guidelines" o BWRVIP-180, "Access Hole Cover Inspection and Flaw Evaluation Guidelines" o BWRVIP-183-A, "Top Guide Grid Beam Inspection and Flaw Evaluation Guidelines" Inspection Services, by an Authorized Inspection Agency, will be applied to the proposed actions of this relief request.

BWRs examine reactor internals in accordance with BWRVIP guidelines. These guidelines are written for the safety significant vessel internal components and provide appropriate examination and evaluation criteria with using appropriate methods and re-examination frequencies. The BWRVIP has established a reporting protocol for examination results and deviations. The NRC has agreed with the BWRVIP approach in principal and is expected to issue Safety Evaluations for many of these BWRVIP guidelines. Therefore, use of these BWRVIP guidelines, as an alternative to the subject Code requirements, provides an acceptable level of quality and safety and will not adversely impact the health and safety of the public.

As additional justification, Enclosure ("Comparison of ASME Section XI Examination Requirements to BWRVIP Examination Requirements"), provides specific examples that compare the inspection requirements of ASME Section XI Item Numbers B13.10, B13.20, B13.30, and B13.40 in Table IWB-2500-1, to the inspection requirements in the BWRVIP documents. Specific BWRVIP documents are provided as examples. This comparison also includes a discussion of the inspection methods.

The BWRVIP provides BWR Vessel and Internals Inspection Summaries to the NRC periodically. Table 1 contains the BWR Vessel and Internals Inspection Summaries transmitted to the NRC that includes CPS. These summaries provide, on a component-by-component basis, the examination methods utilized, the examination frequency to date, and the results of the examinations during the previous interval. These summaries also contain the identified corrective actions. This information reflects the compilation of the BWRVIP outage reports. Corrective actions and examinations performed prior to the BWRVIP were implemented to the requirements of ASME Section XI, as applicable.

10 CFR 50.55a Relief Request I4R-06 Alternative for the Use of the BWRVIP Guidelines in Lieu of Specific ASME Code Requirements on Reactor Pressure Vessel Internals and Components Inspection in Accordance with 10 CFR 50.55a(z)(1)

--Alternative Provides Acceptable Level of Quality and Safety--

Revision 1 (Page 4 of 10)

Table 1 BWR Vessel and Internals Inspection Summaries Unit Accession Number Document Title Document Date Clinton Power Station, Unit 1 ML18040A464 Project No. 704 - BWR Vessel and Internals Inspection Summaries for Spring 2017 Outages (Reference 18)

February 7, 2018 When a BWRVIP guideline refers to ASME Section XI, the technical requirements of ASME Section XI as described by the BWRVIP guideline will be met, but the examination is under the auspices of the BWRVIP program as defined by BWRVIP-94, "BWR Vessel and Internals Project, Program Implementation Guide." The reactor vessel internals inspection program at CPS has been developed and implemented to satisfy the requirements of BWRVIP-94. It is recognized that the BWRVIP executive committee periodically revises the BWRVIP guidelines to address industry operating experience, include enhancements to inspection techniques, and add or adjust flaw evaluation methodologies.

CPS is a BWR/6 design. Table 2 compares present ASME Section XI Examination Category B-N-1 and B-N-2 requirements with the above current BWRVIP guideline requirements, as applicable, to CPS. Therefore, Table 2 only represents the most current comparison. Any deviations from the referenced BWRVIP guidelines for the duration of the proposed alternative will be appropriately documented and communicated to the NRC, per the BWRVIP Deviation Disposition Process.

Note that other requirements (e.g., NUREG-0619, IGSCC) are still implemented separately as Augmented Examination Programs.

In the event that conditions are identified that require repair or replacement and the component is within the jurisdiction of ASME Section XI (welded attachments to the reactor vessel or welded core support structure), the repair or replacement activities will be performed in accordance with ASME Section XI, Article IWA-4000 or a separate relief request will be submitted. Subsequent examinations will be in accordance with the applicable BWRVIP guideline.

As part of the BWRVIP initiative, the BWR reactor internals and attachments were subjected to a safety assessment to identify those components that provide a safety function and to determine if long-term actions were necessary to ensure continued safe operation. The safety functions considered are those associated with (1) maintaining a coolable geometry, (2) maintaining control rod insertion times, (3) maintaining reactivity control, (4) assuring core cooling, and (5) assuring instrumentation availability.

10 CFR 50.55a Relief Request I4R-06 Alternative for the Use of the BWRVIP Guidelines in Lieu of Specific ASME Code Requirements on Reactor Pressure Vessel Internals and Components Inspection in Accordance with 10 CFR 50.55a(z)(1)

--Alternative Provides Acceptable Level of Quality and Safety--

Revision 1 (Page 5 of 10)

6.

Duration of Proposed Alternative Relief is requested for the Fourth ISI Interval for CPS.

7.

Precedents Clinton Power Station, Unit 1, Third ISI Interval Relief Request I3R-10 was authorized by NRC Safety Evaluation (SE) dated April 29, 2016 (ADAMS Accession No. ML16071A233) (Reference 15). This relief request for the Clinton Power Station, Unit 1, Fourth ISI Interval, utilizes a similar approach to the previously approved relief request.

Nine Mile Point Nuclear Power Station, Units 1 and 2 Relief Request I5R-03/I4R-03 was authorized conditionally by NRC SE dated December 13, 2018 (ADAMS Accession No. ML18318A275) (Reference 16).

Peach Bottom Atomic Power Station, Units 2 and 3 Relief Request I5R-03 was authorized conditionally by NRC SE dated July 18, 2018 (ADAMS Accession No. ML18179A394) (Reference 17).

8.

References

1.

"BWRVIP-03: BWR Vessel and Internals Project, Reactor Pressure Vessel and Internals Examination Guidelines"

2.

"BWRVIP-18, Revision 2-A: BWR Vessel and Internals Project, BWR Core Spray Internals Inspection and Flaw Evaluation Guidelines," EPRI Technical Report 3002008089, dated August 2016

3.

Letter from NRC to BWRVIP, "Propriety Version of NRC Staff Review of BWRVIP-27-A, 'BWR Standby Liquid Control System/Core Plate P Inspection and Flaw Evaluation Guidelines,'" dated June 10, 2004

4.

Letter from NRC to BWRVIP, "NRC Approval Letter of BWRVIP-26-A, 'BWR Vessel and Internals Project, BWR Top Guide Inspection and Flaw Evaluation Guidelines,'" dated September 9, 2005

5.

Letter from NRC to BWRVIP, "Final Safety Evaluation of the 'BWR Vessel and Internals Project, BWR Shroud Support Inspection and Flaw Evaluation Guidelines (BWRVIP-38),' EPRI Report TR-108823 (TAC No. M99638)," dated July 24, 2000

6.

"BWRVIP-41, Revision 4-A: BWR Vessel and Internals Project, BWR Jet Pump Assembly Inspection and Flaw Evaluation Guidelines," EPRI Technical Report 3002014254, dated December 2018

10 CFR 50.55a Relief Request I4R-06 Alternative for the Use of the BWRVIP Guidelines in Lieu of Specific ASME Code Requirements on Reactor Pressure Vessel Internals and Components Inspection in Accordance with 10 CFR 50.55a(z)(1)

--Alternative Provides Acceptable Level of Quality and Safety--

Revision 1 (Page 6 of 10)

7.

"BWRVIP-42, Revision 1-A: BWR Vessel and Internals Project, Low Pressure Coolant Injection System (LPCI) Coupling Inspection and Flaw Evaluation Guidelines," EPRI Technical Report 3002010548, dated November 2017

8.

Letter from NRC to BWRVIP, "NRC Approval Letter of BWRVIP-47-A, 'BWR Vessel and Internals Project, BWR Lower Plenum Inspection and Flaw Evaluation Guidelines,'" dated September 9, 2005

9.

Letter from NRC to BWRVIP, "NRC Approval Letter of BWRVIP-48-A, 'BWR Vessel and Internals Project, Vessel ID Attachment Weld Inspection and Flaw Evaluation Guideline,'" dated July 25, 2005

10.

"BWRVIP-76, Revision 1-A: BWR Vessel and Internals Project, BWR Core Shroud Inspection and Flaw Evaluation Guidelines," EPRI Technical Report 3002005566, dated April 2015

11.

"BWRVIP-94: BWR Vessel and Internals Project, Program Implementation Guide"

12.

BWRVIP-138, Revision 1-A: BWR Vessel and Internals Project, Updated Jet Pump Beam Inspection and Flaw Evaluation Guidelines," EPRI Technical Report 1025136, dated October 2012

13.

"BWRVIP-180: BWR Vessel and Internals Project, Access Hole Cover Inspection and Flaw Evaluation Guidelines," EPRI Technical Report 1013402, dated November 2007

14.

"BWRVIP-183-A: BWR Vessel and Internals Project, Top Guide Grid Beam Inspection and Flaw Evaluation Guidelines," EPRI Technical Report 3002010551, dated November 2017

15.

Letter from T. Tate (NRC) to B. Hanson (EGC), "Clinton Power Station, Unit 1 and Nine Mile Point Nuclear Station, Units 1 and 2 - Relief Request Alternative RE: Use of Boling Water Reactor Vessel and Internals Project Guidelines in Lieu of Specific ASME Code Requirements (CAC Nos. MF6116 and MF6117)," dated April 29, 2016 (ADAMS Accession No. ML16071A233)

16.

Nine Mile Point Nuclear Station, Units 1 and 2 - Issuance of Relief Requests Re:

Use of Boiling Water Reactor Vessel and Internals Project Guidelines in Lieu of Specific ASME Code Requirements (EPID L-2018-LLR-0085), dated December 13, 2018 (ADAMS Accession No. ML18318A275)

17.

Letter from J. G. Danna (NRC) to B. C. Hanson (EGC), "Peach Bottom Atomic Power Station, Units 2 and 3 - Safety Evaluation of Relief Request I5R-03 Regarding the Fifth 10-Year Interval of the Inservice Inspection Program (EPID

10 CFR 50.55a Relief Request I4R-06 Alternative for the Use of the BWRVIP Guidelines in Lieu of Specific ASME Code Requirements on Reactor Pressure Vessel Internals and Components Inspection in Accordance with 10 CFR 50.55a(z)(1)

--Alternative Provides Acceptable Level of Quality and Safety--

Revision 1 (Page 7 of 10)

No. L-2018-LLR-0056)," dated July 18, 2018 (ADAMS Accession No. ML18179A394)

18.

Letter 2018-015 from BWRVIP to NRC, "Project No. 704 - BWR Vessel and Internals Inspection Summaries for Spring 2017 Outages," dated February 7, 2018 (ADAMS Accession No. ML18040A464)

9.

Enclosure Comparison of ASME Section XI Examination Requirements to BWRVIP Examination Requirements

10 CFR 50.55a Relief Request I4R-06 Alternative for the Use of the BWRVIP Guidelines in Lieu of Specific ASME Code Requirements on Reactor Pressure Vessel Internals and Components Inspection in Accordance with 10 CFR 50.55a(z)(1)

--Alternative Provides Acceptable Level of Quality and Safety--

Revision 1 (Page 8 of 10)

TABLE 2 Comparison of ASME Section XI Examination Category B-N-1 and B-N-2 Requirements with BWRVIP Guidance Requirements1 ASME Item Section XI No. Table IWB-2500-1 Component ASME Section XI Exam Scope ASME Section XI Exam ASME Section XI Frequency Authorized Alternative BWRVIP Exam Scope BWRVIP Exam BWRVIP Frequency B13.10 Reactor Vessel Interior Reactor Vessel Interior Accessible Areas VT-3 Each period BWRVIP-18-R2-A, 26-A, 27-A, 38, 41-R4-A, 42-R1-A, 47-A, 48-A, 76-R1-A, 138-R1-A, 180, and 183-A Overview examinations of components during BWRVIP examinations are performed to satisfy ASME Section XI VT-3 visual examination requirements.

B13.20 Interior Attachments Within Beltline Region Jet Pump Riser Braces Accessible Welds VT-1 Each 10-year Interval BWRVIP-48-A, Table 3-2 Riser Brace Attachment EVT-1 25% during each 6 years Lower Surveillance Specimen Holder Brackets BWRVIP-48-A, Table 3-2 Bracket Attachment VT-1 Each 10-year Interval B13.30 Interior Attachments Beyond Beltline Steam Dryer Hold-Down Brackets Accessible Welds VT-3 Each 10-year Interval BWRVIP-48-A, Table 3-2 Bracket Attachment VT-3 Each 10-year Interval Guide Rod Brackets BWRVIP-48-A, Table 3-2 Bracket Attachment VT-3 Each 10-year Interval Steam Dryer Support Brackets BWRVIP-48-A, Table 3-2 Bracket Attachment EVT-1 Each 10-year Interval Feedwater Sparger Brackets BWRVIP-48-A, Table 3-2 Bracket Attachment EVT-1 Each 10-year Interval Core Spray Piping Brackets BWRVIP-48-A, Table 3-2 Bracket Attachment EVT-1 100% every 4 refueling cycles Upper Surveillance Specimen Holder Brackets BWRVIP-48-A, Table 3-2 Bracket Attachment VT-3 Each 10-year Interval

10 CFR 50.55a Relief Request I4R-06 Alternative for the Use of the BWRVIP Guidelines in Lieu of Specific ASME Code Requirements on Reactor Pressure Vessel Internals and Components Inspection in Accordance with 10 CFR 50.55a(z)(1)

--Alternative Provides Acceptable Level of Quality and Safety--

Revision 1 (Page 9 of 10)

TABLE 2 Comparison of ASME Section XI Examination Category B-N-1 and B-N-2 Requirements with BWRVIP Guidance Requirements1 ASME Item Section XI No. Table IWB-2500-1 Component ASME Section XI Exam Scope ASME Section XI Exam ASME Section XI Frequency Authorized Alternative BWRVIP Exam Scope BWRVIP Exam BWRVIP Frequency Shroud Support Welds BWRVIP-38, 3.3, Figure 3-5 Weld H9 EVT-1 or UT Based on as-found conditions, to a maximum of 6 years for EVT-1, 10 years for UT Shroud Support Leg (Weld H12)

Accessible Welds (Beneath core plate, rarely accessible)

VT-3 Each 10-year Interval BWRVIP-38, 3.2.3 Weld H12 Per BWRVIP-38 NRC SE (07/24/00),

examine with appropriate method2 When accessible B13.40 Core Support Structure Shroud Support Accessible Surfaces VT-3 Each 10-year Interval BWRVIP-38, 3.3, Appendix A Figures 3-4 and 3-5 Welds H8 and H9 EVT-1 or UT Based on as-found conditions, to a maximum of 6 years for EVT-1, 10 years for UT Shroud Support Legs Accessible Surfaces (beneath core plate, rarely accessible)

BWRVIP-38, 3.2.3 Shroud support leg welds Per BWRVIP-38 NRC SE (07/24/00),

examine with appropriate method2 When accessible Shroud Vertical Welds Accessible Surfaces BWRVIP-76-R1-A, 3.3, Figure 3-2 Vertical Welds EVT-1 or UT Maximum of 6 years for one-sided EVT-1, 10 years for UT

10 CFR 50.55a Relief Request I4R-06 Alternative for the Use of the BWRVIP Guidelines in Lieu of Specific ASME Code Requirements on Reactor Pressure Vessel Internals and Components Inspection in Accordance with 10 CFR 50.55a(z)(1)

--Alternative Provides Acceptable Level of Quality and Safety--

Revision 1 (Page 10 of 10)

TABLE 2 Comparison of ASME Section XI Examination Category B-N-1 and B-N-2 Requirements with BWRVIP Guidance Requirements1 ASME Item Section XI No. Table IWB-2500-1 Component ASME Section XI Exam Scope ASME Section XI Exam ASME Section XI Frequency Authorized Alternative BWRVIP Exam Scope BWRVIP Exam BWRVIP Frequency Shroud Repairs3 Accessible Surfaces BWRVIP-76-R1-A, 3.5 Tie-Rod Repair VT-3 Per repair designer recommendations, per BWRVIP-76-R1-A NOTES:

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.

2) When inspection tooling and methodologies are available, they will be utilized to establish a baseline inspection of these welds.

3) CPS has a tie-rod shroud repair.

Enclosure 10 CFR 50.55a Relief Request I4R-06 Alternative to Use BWRVIP Guidelines in Lieu of Specific ASME Code Requirements on Reactor Pressure Vessel Internals and Components Inspection in Accordance with 10 CFR 50.55a(z)(1)

--Alternative Provides Acceptable Level of Quality or Safety--

Revision 1 (Enclosure Page 1 of 5)

Comparison of ASME Section XI Examination Requirements to BWRVIP Examination Requirements The following paragraphs provide a comparison of the examination requirements in ASME Section XI, Table IWB-2500-1, Item Numbers B13.10, B13.20, B13.30, and B13.40, to the examination requirements in the BWRVIP guidelines. Specific BWRVIP guidelines are provided as examples for comparisons. This comparison also includes a discussion of the examination methods.

1.

ASME Section XI Requirement - B13.10 - Reactor Vessel Interior Accessible Areas (B-N-1)

ASME Section XI requires a VT-3 visual examination of reactor vessel accessible areas, which are defined as the spaces above and below the core made accessible during normal refueling outages. The frequency of these examinations is specified as the first refueling outage, and at intervals of approximately three years, during the First ISI Interval, and each inspection period during each successive 10-year ISI Interval.

Typically, these examinations are performed every inspection period during the 10-year ISI Interval. This examination requirement is a non-specific requirement that is a departure from the traditional ASME Section XI examinations of welds and surfaces. As such, this requirement has been interpreted and satisfied differently across the domestic fleet. The purpose of the examination is to identify relevant conditions such as distortion or displacement of parts; loose, missing, or fractured fasteners; foreign material, corrosion, erosion, or accumulation of corrosion products, wear, and structural degradation.

Portions of the various examinations required by the applicable BWRVIP guidelines require examination of accessible areas of the reactor vessel during refueling outages.

Examination of core spray piping and spargers (BWRVIP-18-R2-A), top guide (BWRVIP-26-A), shroud support (BWRVIP-38), jet pump welds and components (BWRVIP-41-R4-A), LPCI couplings (BWRVIP-42-R1-A), lower plenum components (BWRVIP-47-A) interior attachments (BWRVIP-48-A), core shroud welds, (BWRVIP-76-R1-A), access hole cover (BWRVIP-180), and top guide grid beams (BWRVIP-183-A) provides such access. Locating and examining specific welds and components within the reactor vessel areas above, below (if accessible), and surrounding the core (annulus area) entails access by remote camera systems that essentially perform equivalent VT-3 visual examination of these areas or spaces as the specific weld or component examinations are performed. This provides an equivalent method of visual examination on a more frequent basis than that required by ASME Section XI. Evidence of wear, structural degradation, loose, missing, or displaced parts, foreign materials, and corrosion product buildup can be, and has been observed during the course of implementing these BWRVIP examination requirements.

Therefore, the specified BWRVIP guideline requirements meet or exceed the subject ASME Section XI requirements (including method and frequency requirements) for

Enclosure 10 CFR 50.55a Relief Request I4R-06 Alternative to Use BWRVIP Guidelines in Lieu of Specific ASME Code Requirements on Reactor Pressure Vessel Internals and Components Inspection in Accordance with 10 CFR 50.55a(z)(1)

--Alternative Provides Acceptable Level of Quality or Safety--

Revision 1 (Enclosure Page 2 of 5) examination of the interior of the reactor vessel. Accordingly, these BWRVIP examination requirements provide an acceptable level of quality and safety as compared to the subject ASME Section XI requirements.

2.

ASME Section XI Requirement - B13.20 - Interior Attachments Within the Beltline (B-N-2)

ASME Section XI requires a VT-1 visual examination of accessible reactor vessel interior surface attachment welds within the beltline each 10-year interval. In the General Electric (GE) Company BWR/6 design, this includes the jet pump riser brace welds-to-reactor vessel wall and the lower surveillance specimen support bracket welds-to-reactor vessel wall. In comparison, the BWRVIP requires the same examination method and frequency for the lower surveillance specimen support bracket welds, and requires an enhanced VT-1 (EVT-1) visual examination of the remaining attachment welds in the beltline region in the first 12 years, and then 25% during each subsequent 6 years.

The jet pump riser brace examination requirements are provided below to show a comparison between ASME Section XI and the BWRVIP examination requirements.

Comparison to BWRVIP Requirements - Jet Pump Riser Braces BWRVIP-48-A ASME Section XI requires a 100% VT-1 visual examination of the jet pump riser brace-to-reactor vessel wall pad welds each 10-year interval.

BWRVIP-48-A requires an EVT-1 visual examination of the jet pump riser brace-to-reactor vessel wall pad welds and heat affected zones 25% each subsequent 6 years.

BWRVIP-48-A specifically defines the susceptible regions of the attachment that are to be examined.

ASME Section XI VT-1 visual examination is conducted to detect discontinuities and imperfections on the surfaces of components, including such conditions as cracks, wear, corrosion, or erosion. The BWRVIP EVT-1 visual examination is conducted to detect discontinuities and imperfections on the surface of components and is additionally specified to detect potentially very tight cracks characteristic of fatigue and intergranular stress corrosion cracking (IGSCC), the relevant degradation mechanisms for these components. General wear, corrosion, or erosion although generally not a concern for inherently tough, corrosion resistant stainless steel material, would also be detected during the process of performing a BWRVIP EVT-1 visual examination.

ASME Section XI VT-1 visual examination method requires that at a maximum distance of 2 feet or a letter character with a maximum height of 0.044 inches can be read. The BWRVIP EVT-1 visual examination method requires resolution of 0.044 inch characters on the examination surface and additionally the performance of a cleaning assessment and cleaning as necessary. BWRVIP-48-A includes a diagram for the configuration and prescribes examination for each configuration including CPS.

Enclosure 10 CFR 50.55a Relief Request I4R-06 Alternative to Use BWRVIP Guidelines in Lieu of Specific ASME Code Requirements on Reactor Pressure Vessel Internals and Components Inspection in Accordance with 10 CFR 50.55a(z)(1)

--Alternative Provides Acceptable Level of Quality or Safety--

Revision 1 (Enclosure Page 3 of 5)

The calibration standards used for BWRVIP EVT-1 visual examinations utilize the ASME Section XI characters, thus assuring at least equivalent resolution compared to the ASME Section XI requirements. Although the BWRVIP examination may be less frequent, it is a more comprehensive method. Therefore, the enhanced flaw detection capability of an EVT-1 visual examination with a less frequent examination schedule provides an acceptable level of quality and safety to that provided by ASME Section XI.

3.

ASME Section XI Requirement - B13.30 - Interior Attachment Beyond the Beltline Region (B-N-2)

ASME Section XI requires a VT-3 visual examination of accessible reactor vessel interior surface attachment welds beyond the beltline each 10-year interval. In the BWR/6 design, this includes the core spray piping support bracket welds-to-reactor vessel wall, the upper surveillance specimen support bracket welds-to-reactor vessel wall, the feedwater sparger support bracket welds-to-reactor vessel wall, the steam dryer support welds-to-reactor vessel wall, the guide rod support bracket weld-to-reactor vessel wall, and the shroud support plate-to-reactor vessel weld. BWRVIP-48-A requires as a minimum the same VT-3 visual examination method as ASME Section XI for some of the interior attachment welds beyond the beltline region, and in some cases specifies an EVT-1 for these welds. For those interior attachment welds that have the same VT-3 method of visual examination, the same scope of examination (accessible welds), the same examination frequency (each 10-year interval), and the same ASME Section XI flaw evaluation criteria are used. Therefore, the level of quality and safety provided by the BWRVIP requirements are equivalent to that provided by ASME Section XI.

For the core spray support bracket attachment welds, the steam dryer support bracket attachment welds, the feedwater sparger support bracket attachment welds, and the shroud support plate-to-reactor vessel welds, the BWRVIP guidelines require an EVT-1 visual examination at the same frequency as ASME Section XI, or at a more frequent rate. Therefore, the BWRVIP enhanced examination requirements provide the same level of quality and safety compared to that provided by ASME Section XI.

The feedwater sparger bracket-to-reactor vessel attachment weld is used as an example for comparison between ASME Section XI and BWRVIP examination requirements as discussed below.

Comparison to BWRVIP Requirements - Feedwater Sparger Bracket Welds (BWRVIP-48-A)

The ASME Section XI examination requirement is a VT-3 visual examination of each weld every 10 years.

The BWRVIP-48-A visual examination requirement is an EVT-1 for the feedwater sparger bracket attachment welds with each weld examined every 10 years.

Enclosure 10 CFR 50.55a Relief Request I4R-06 Alternative to Use BWRVIP Guidelines in Lieu of Specific ASME Code Requirements on Reactor Pressure Vessel Internals and Components Inspection in Accordance with 10 CFR 50.55a(z)(1)

--Alternative Provides Acceptable Level of Quality or Safety--

Revision 1 (Enclosure Page 4 of 5)

The BWRVIP-48-A visual examination method EVT-1 has superior flaw detection and sizing capability, the examination frequency is the same as the ASME Section XI requirements, and the same flaw evaluation criteria are used.

ASME Section XI VT-3 visual examination is conducted to detect component structural integrity by ensuring the components general condition is acceptable. An EVT-1 visual examination is conducted to detect discontinuities and imperfections on the examination surfaces, including such conditions as tight cracks caused by IGSCC or fatigue, and the relevant degradation mechanisms for BWR internal attachments.

Therefore, because the EVT-1 visual examination method provides the same examination scope (accessible welds), the same examination frequency in most cases, and the same flaw evaluation criteria as ASME Section XI, the level of quality and safety provided by the BWRVIP criteria meets or exceeds that provided by the ASME Section XI requirements.

4.

ASME Section XI Requirement - B13.40 - Core Support Structures (B-N-2)

ASME Section XI requires a VT-3 visual examination of accessible surfaces of the reactor vessel core support structure each 10-year interval. In the BWR/6 design, the core support structure has primarily been considered the shroud support structure, including the shroud. Historically, this requirement has been interpreted and satisfied differently across the industry. The proposed alternate examinations replace this ASME Section XI requirement with specific BWRVIP guidelines that examine susceptible locations for known relevant degradation mechanisms.

Comparison to BWRVIP Requirements - Shroud Supports (BWRVIP-38)

ASME Section XI requires a VT-3 visual examination of accessible surfaces each 10-year interval.

The BWRVIP-38 requires an EVT-1 visual examination every 6 years or ultrasonic examination (UT) every 10 years.

BWRVIP recommended examinations of core support structures are focused on the known susceptible areas of this structure, including the welds and associated weld heat affected zones. In many locations, the BWRVIP guidelines require a UT of the susceptible welds at a frequency identical to the ASME Section XI requirement.

The BWRVIP guidelines require an EVT-1 or UT of core support structures. The core shroud is used as an example for comparison between the ASME Section XI and BWRVIP examination requirements as shown below.

Enclosure 10 CFR 50.55a Relief Request I4R-06 Alternative to Use BWRVIP Guidelines in Lieu of Specific ASME Code Requirements on Reactor Pressure Vessel Internals and Components Inspection in Accordance with 10 CFR 50.55a(z)(1)

--Alternative Provides Acceptable Level of Quality or Safety--

Revision 1 (Enclosure Page 5 of 5)

Comparison to BWRVIP Requirements - Core Shroud (BWRVIP-76-R1-A)

Shroud repair Tie-Rods have been installed at CPS. Therefore, BWRVIP-76-R1-A requires inspection of the vertical shroud welds and the Tie-Rod repair hardware.

ASME Section XI requires a VT-3 visual examination of accessible surfaces each 10-year interval.

The BWRVIP requires an EVT-1 visual examination or UT of shroud vertical welds every 10-years minimum, as compared to the ASME Section XI requirement (VT-3).

For Shroud Repairs, the BWRVIP requires a VT-3 visual examination and other appropriate techniques to examine the Tie-Rod repair hardware every ten years.

Therefore, the BWRVIP referenced examinations are the same or superior to ASME Section XI requirements. Shroud vertical welds and repair Tie-Rod examinations are recommended in BWRVIP-76-R1-A and have the same basic VT-3 method of visual examination or better, the same examination frequency (each 10-year interval) and comparable flaw evaluation criteria. Therefore, the BWRVIP requirements provide a level of quality and safety equivalent to that provided by ASME Section XI.

For other core support structure components, the BWRVIP requires an EVT-1 visual examination or UT of core support structures.

Summary The BWRVIP recommended examinations specify locations that are known to be vulnerable to BWR relevant degradation mechanisms rather than accessible surfaces.

The BWRVIP examination methods (EVT-1 or UT) are superior to the ASME Section XI required VT-3 visual examination for flaw detection and characterization. In most cases, the BWRVIP examination frequency is equivalent to or more frequent than the examination frequency required by ASME Section XI. In cases where the BWRVIP examination frequency is less frequent than required by ASME Section XI, the BWRVIP examinations are performed in a more comprehensive manner and focus on the areas most vulnerable. Therefore, the superior flaw detection and characterization capability, with an equivalent or more frequent examination frequency, or with a less frequent examination frequency but with those examinations being performed in a more comprehensive manner, and using comparable flaw evaluation criteria, results in the BWRVIP criteria providing a level of quality and safety equivalent to or superior to that required by the ASME Section XI requirements.