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NEI Slides - Risk Insights for Aging Management Presentation June 2, 2022
	ML22152A094
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Issue date:	06/02/2022
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	Johnson M, 301-415-5861
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Leveraging Risk Insights in Aging Management June 2, 2022

Agenda Background and Overview Brett Titus Nuclear Energy Institute (NEI)

Jolynn Oquist Barry Thurston Fernando Ferrante Dylan Cimock Selective Leaching Xcel Energy Constellation Energy EPRI* EPRI Andrew Burgess Drew Mantey Jessica Bock Inaccessible Non-EQ Cables Ameren Missouri EPRI EPRI Brett Titus Next Steps NEI

EPRI - Electric Power Research Institute ©2022 Nuclear Energy Institute 2

Background and Overview Risk Insights for Aging Management Since 1995, the NRC and industry have significantly expanded use of PRA & risk insights:

Maintenance Rule

Risk-informed Oversight

Risk-Informed Plant Licensing Basis Changes

Risk-Informed In-Service Inspection

Risk-Informed Categorization of SSCs (§50.69)

Risk-Informed Technical Specifications

Risk-Informed Fire Protection All operating reactors have invested heavily on site-specific PRA models that added significant quality and level of detail since the 1990s While the focus of each risk-informed application may be different, there are insights that can be leveraged to inform aging management effects

Risk Insights for Aging Management CY22 - Development of NEI Technical Report on Risk Insights for Aging Management May 2, 2022 - Publication of EPRI Report, Leveraging Risk Insights for Aging Management Program Implementation: 2022 March 10, 2022 - Regulatory Information Conference Technical Session (https://ric.nrc.gov/docs/abstracts/sessionabstract-33.html)

January 12, 2022 - Submitted Selective Leaching and Inaccessible Cable AMP mark-ups for incorporation into GALL-SLR and GALL

Selective Leaching

Background

Utility implementation of the Selective Leaching (SL) Aging Management Program (AMP) has identified areas for improvement Selective Leaching industry operating experience provides new information that can be used in revising the Selective Leaching AMP Ongoing research by the industry and EPRI has identified opportunities to improve the effectiveness and efficiency of the Selective Leaching AMP

Intent Of Proposed Changes to SL AMP Objective 1: improve clarity of element 4 by re-structuring from long paragraphs to bullets and tables, using XI.M41 as a model.

Objective 2: introduce the allowance for new NDE techniques, based on recent advancements and demonstrations of NDE technology Objective 3: introduce use of risk-insights into sample methodologies Objective 4: streamline the required corrective actions to credit utilities well-established Corrective Action Program to determine appropriate extent of condition and extent of cause commensurate with safety significance

SL - Staff Question #1 Inspection Sample Size Reduction Response Summary The extent of inspections for selective leaching NEI proposal provides the option to use existing GALL-SLR during the subsequent period of extended sampling requirements or a risk-informed sampling operation (i.e., 3 percent with a maximum of 10 methodology.

components per GALL-SLR guidance) was reduced when compared to the extent of inspections for selective leaching during the initial Proposed revisions to Element 4 restructured existing sampling requirements into a tabular format - but did not period of extended operation (i.e., 20 percent change sampling quantities.

with a maximum of 25 components per GALL Report, Revision 2 guidance) based on six deterministic factors outlined in NUREG-2222, Risk-informed sampling methodology may not reduce the Disposition of Public Comments on the Draft number of components inspected.

Subsequent License Renewal Guidance Documents NUREG-2191 and NUREG-2192.

Risk-informed sampling methodology will drive smarter sampling than existing guidance.

The NEI document proposes a further reduction down to 2-3 components per population. Please provide the technical basis for this reduction. The risk insights framework was developed very similarly to other previously NRC-approved risk-informed categorization methodologies.

SL - Staff Question #1 Inspection Sample Size Reduction Detailed Response The extent of inspections for selective leaching Large revisions to Element 4 were largely focused on during the subsequent period of extended recommending a re-structuring of the existing content to operation (i.e., 3 percent with a maximum of 10 improve the readability and flow of the AMP. Changes included taking large paragraphs and converting into a components per GALL-SLR guidance) was table format with footnotes and bullet points, similar to how reduced when compared to the extent of XI.M41 is structured.

inspections for selective leaching during the initial period of extended operation (i.e., 20 percent with a maximum of 25 components per GALL New proposed Table XI.M33-1 addresses inspections on a per unit basis, including for all populations 3%, maximum Report, Revision 2 guidance) based on six of 10 components - consistent with GALL-SLR.

deterministic factors outlined in NUREG-2222, Disposition of Public Comments on the Draft Subsequent License Renewal Guidance Risk-informed sampling methodology results in the same Documents NUREG-2191 and NUREG-2192. number or more inspections for sample populations up to 116.

The NEI document proposes a further reduction At the pilot plant in the EPRI study, proposed risk-informed down to 2-3 components per population. Please sampling methodology would result in more inspections provide the technical basis for this reduction. than required by current GALL-SLR requirements.

SL - Staff Question #1 Inspection Sample Size Reduction Detailed Response (cont.)

The extent of inspections for selective leaching Lesser inspection quantities are justified during the subsequent period of extended considering:

operation (i.e., 3 percent with a maximum of 10

Current guidance is susceptibility/probability biased.

components per GALL-SLR guidance) was Component consequence of failure is not considered.

reduced when compared to the extent of Risk-informed sampling methodology considers both inspections for selective leaching during the initial susceptibility/probability and consequence of failure.

period of extended operation (i.e., 20 percent

Risk-informed sampling is based on a systematic, with a maximum of 25 components per GALL structured process that identifies the highest risk Report, Revision 2 guidance) based on six components in a given population and selects inspection deterministic factors outlined in NUREG-2222, samples based on assessing the structural integrity of those highest risk components.

Disposition of Public Comments on the Draft Subsequent License Renewal Guidance

Guidance on inspection sample selection does not need Documents NUREG-2191 and NUREG-2192. to drive inspections of components whose failure is within currently acceptable bounds of incremental plant safety risk as determined through PRA.

The NEI document proposes a further reduction

Populations are overly inflated if lower risk components down to 2-3 components per population. Please are included; however, they should be (and are) considered for inspection as surrogates.

provide the technical basis for this reduction.

Proposed guidance is intended to set the minimum required inspections given that populations will vary significantly.

SL - Staff Question #1 Inspection Sample Size Reduction Detailed Response (cont.)

The extent of inspections for selective leaching Similar RI-categorization and sampling during the subsequent period of extended methodologies have been applied to pressure operation (i.e., 3 percent with a maximum of 10 boundary components and approved by the NRC:

components per GALL-SLR guidance) was

Foundational methodology is in NRC-approved topical reduced when compared to the extent of report TR-112657, REV B-A.

inspections for selective leaching during the initial period of extended operation (i.e., 20 percent with a maximum of 25 components per GALL

A key component of this methodology is the EPRI RI-ISI Risk Matrix, in which pressure boundary components are Report, Revision 2 guidance) based on six assigned to one of seven risk categories based upon the deterministic factors outlined in NUREG-2222, results of separate and independent evaluations (i.e.

Disposition of Public Comments on the Draft consequence of failure set to 1.0, failure potential Subsequent License Renewal Guidance evaluation is conducted even if the consequence of Documents NUREG-2191 and NUREG-2192. failure is low).

Significant industry experience with applying RI-ISI to The NEI document proposes a further reduction safety related and non-safety related systems has shown down to 2-3 components per population. Please portions of the pressure boundary receiving increased provide the technical basis for this reduction. inspections (e.g. those with higher failure potential and consequence). Other portions of the pressure boundary may see a reduction in inspections.

SL - Staff Question #1 Inspection Sample Size Reduction Detailed Response (cont.)

The extent of inspections for selective leaching Similar RI-categorization and sampling during the subsequent period of extended methodologies have been applied to pressure operation (i.e., 3 percent with a maximum of 10 boundary components and approved by the NRC:

components per GALL-SLR guidance) was reduced when compared to the extent of

Per TR-112657, REV B-A, eliminating a large population inspections for selective leaching during the initial of piping inspections in safety related systems in lowest period of extended operation (i.e., 20 percent risk locations will have a negligible on plant risk, to the with a maximum of 25 components per GALL point that a quantitative change in risk assessment is not Report, Revision 2 guidance) based on six required when eliminating these inspections.

deterministic factors outlined in NUREG-2222, Disposition of Public Comments on the Draft

Industry experience with RI-ISI has shown that when Subsequent License Renewal Guidance there is a reduction in the inspection population for other Documents NUREG-2191 and NUREG-2192. risk categories, the NRC approved change in risk acceptance criteria is always met. Further demonstrating the robustness of the evaluation processes (e.g.

The NEI document proposes a further reduction consequence of failure, failure potential), criteria (e.g.

down to 2-3 components per population. Please CCDP/CLERP ranges) and inspection populations.

provide the technical basis for this reduction.

SL - Staff Question #1 GALL-SLR Proposed Changes

SL - Staff Question #1 GALL-SLR Proposed Changes Stations that have applied the industry-accepted risk framework (EPRI TU 3002020623 Leveraging Risk Insights for Aging Management Program Implementation Update) to the AMP have the option of using risk-informed inspection sample selection or the 3% of population/10 components inspection sampling methodology.

Risk-informed sampling methodology:

Any SSCs that could not be fully evaluated for the likelihood and/or consequence risk factor using the risk framework must be placed in the high category for the applicable risk factor(s).

A minimum of 2 SSCs classified as high consequence, regardless of likelihood, in each applicable population must be included in the inspection sample.

This minimum number of high consequence SSCs to be inspected may be reduced to 1 if 2 or more surrogates are inspected. A surrogate is defined as an SSC within the same population with the same or higher likelihood of failure, but with a lower consequence of failure.

For populations with no high consequence SSCs, a minimum of 2 SSCs should be inspected, with a focus on assessing the structural integrity of the higher consequence SSCs in the population. The SSCs to be inspected can be selected from either the highest consequence group or surrogates.

Stations must retain auditable records of the risk framework results and update these results as new information becomes available that may change the initial results.

SL - Staff Question #2 Re-Introduction of Hardness Testing Response Summary Hardness testing was replaced with Hardness testing was proposed to be re-mechanical examination techniques and introduced as it can be an effective means to destructive examinations with the issuance of support detection of selective leaching.

GALL-SLR.

The intent of re-introducing hardness testing was to maximize the number of available Hardness testing can theoretically identify the inspection techniques utilities are able to presence of selective leaching but is unable to leverage in order to detect the presence of the characterize the extent of selective leaching. selective leaching in components.

Please provide the technical basis for re-introducing hardness testing.

SL - Staff Question #2 Re-Introduction of Hardness Testing Detailed Response Hardness testing was replaced with Hardness testing is a point measurement and does not reveal information about the condition of a component in mechanical examination techniques other areas away from where the test was done.

and destructive examinations with the issuance of GALL-SLR.

However, hardness testing is proven to identify whether selective leaching has occurred where the test has been done.

Hardness testing can theoretically The proposed wording of XI.M33 acknowledges that it is identify the presence of selective not effective at characterizing the extent or depth of leaching but is unable to characterize selective leaching.

the extent of selective leaching.

Industry operating experience has found successful use of hardness testing in conjunction with visual exams.

Please provide the technical basis for re-introducing hardness testing. As such, it can be a useful tool to confirm selective leaching in suspected areas found through visual inspection. In this context, hardness testing can improve the objectivity of visual inspection and should not be discarded.

SL - Staff Question #2 Re-Introduction of Hardness Testing Detailed Response Hardness testing was replaced with Proposed changes to Element 4 also state, If mechanical examination techniques and a given inspection method yields inconclusive destructive examinations with the or potentially unsatisfactory results, a more issuance of GALL-SLR. capable method may be chosen for follow-up inspection and disposition of results.

Hardness testing can theoretically The proposed changes are structured such identify the presence of selective that if acceptance criteria were not satisfied, leaching but is unable to characterize the inspection would either need to be the extent of selective leaching. considered unsatisfactory, or the extent of selective leaching would need to be further investigated using more capable techniques.

Please provide the technical basis for re-introducing hardness testing. Use of hardness testing is analogous to a screening approach for selective leaching.

SL - Staff Question #2 Proposed Changes

SL - Staff Question #3 Credit for Undefined Future NDE Techniques Response Summary The NEI document introduces [n]ondestructive Selective leaching is an inherently difficult aging examination techniques demonstrated to be capable of mechanism to detect. The proposed revisions to XI.M33 detecting the presence and/or extent of selective leaching include recommendations to permit the use of on the component as an inspection method. nondestructive examination techniques in order to maximize the available methods that utilities can leverage in order to detect selective leaching.

The AMP should identify specific NDE techniques which are capable of detecting selective leaching in cast irons and copper alloys. (See reference below which notes that Recommendations to permit NDE techniques are based NDE for selective leaching has not achieved widespread largely on EPRI research (see next page), including 2 acceptance.) recently published reports in 2021.

Uhligs Corrosion Handbook, 3rd Edition, page

3002020830, Ultrasonic NDE Techniques for 148, "Several researchers have reported on Detection of Selective Leaching in Complex Shaped attempts to develop method of in situ Gray Cast Iron Components nondestructive inspection for dealloying, but they

3002020832, Electromagnetic NDE Techniques for have not achieved widespread acceptance." Detection of Selective Leaching in Gray Cast Iron Piping

SL - Staff Question #3 EPRI Selective Leaching NDE Research Title Product ID Year Selective Leaching NDE Technical Basis Document - 2022 Research TBD 2022 Update Ultrasonic NDE Techniques for Detection of Selective Leaching in 3002020830 2021 Complex Shaped Gray Cast Iron Components Electromagnetic NDE Techniques for Detection of Selective 3002020832 2021 Leaching in Gray Cast Iron Piping Selective Leaching: State-of-the-Art Technical Update 3002016057 2019 Guidance for Conducting Ultrasonic Examinations for the Detection of 3002013168 2018 Selective Leaching Assessment of Available Nondestructive Evaluation Techniques for 3002008013 2016 Selective Leaching: Technology Review Correlation of Selectively Leaching Thickness to Hardness for Gray Cast 1025218 2012 Iron and Brass Update to NDE for Selective Leaching of Gray Cast Iron Components 1019111 2009 NDE for Selective Leaching of Gray Cast Iron Components 1018939 2009

SL - Staff Question #3 Credit for Undefined Future NDE Techniques Detailed Response The NEI document introduces [n]ondestructive Proposed wording to address NDE techniques in XI.M33 examination techniques demonstrated to be capable of specified that the techniques shall be volumetric in nature.

detecting the presence and/or extent of selective leaching More specific forms of NDE were not listed for the following on the component as an inspection method. reasons:

The AMP should identify specific NDE techniques which

Use of the term volumetric was intended to capture both are capable of detecting selective leaching in cast irons ultrasonic and electromagnetic techniques recently and copper alloys. (See reference below which notes that demonstrated in EPRI research.

NDE for selective leaching has not achieved widespread acceptance.)

Many electromagnetic NDE techniques go by vendor-specific

Uhligs Corrosion Handbook, 3rd Edition, page 148, names.

"Several researchers have reported on attempts to develop method of in situ nondestructive inspection for dealloying, but they have not achieved

Use of the generic term volumetric aligns with similar wording widespread acceptance." found in other AMPs (e.g., XI.M30, XI.M38, XI.M41) and was intended to convey that the methods would be capable of detecting wall loss (vs. surface techniques).

Desire for flexibility in AMP implementation to allow use of technology as it continues to evolve and advance beyond todays state-of-the-art. A statement included that the NDE methods must be demonstrated to be able to detect selective leaching. Similar concepts can be found in XI.M41 Element 4.

SL - Staff Question #3 Credit for Undefined Future NDE Techniques Detailed Response The NEI document introduces [n]ondestructive Each inspection technique referenced for SL (visual, examination techniques demonstrated to be capable of mechanical, hardness) will have their own specific set of detecting the presence and/or extent of selective leaching capabilities and limitations. Allowance for relatively new, or on the component as an inspection method. future, NDE techniques is intended to permit utilities to better leverage new technology to more effectively and efficiently implement this aging management program.

The AMP should identify specific NDE techniques which are capable of detecting selective leaching in cast irons and copper alloys. (See reference below which notes that NDE for selective leaching has not achieved widespread acceptance.)

Uhligs Corrosion Handbook, 3rd Edition, page 148, "Several researchers have reported on attempts to develop method of in situ nondestructive inspection for dealloying, but they have not achieved widespread acceptance."

SL - Staff Question #4 Reliance on One Inspection Technique Response Summary GALL-SLR Report AMP XI.M33 recommends The referenced wording in Question #4, cited visual/mechanical and destructive from the proposed NEI revisions, was not examinations for each population. intended to address the quantity of inspection techniques that are to be performed.

The NEI proposal states [i]nspections and examinations may consist of any [of] the Rather - the cited paragraph was intended to following methods (referring to either simply introduce the types of inspections that visual/mechanical, hardness, nondestructive, are acceptable in a more structured manner:

or destructive examinations).

By material type

In successive order of increasing complexity (to Please provide the basis for going from two deploy) and capability of detection inspections techniques in our current guidance down to one inspection technique.

SL - Staff Question #4 Reliance on One Inspection Technique Detailed Response GALL-SLR Report AMP XI.M33 recommends Inspection quantities listed in proposed Table XI.M33-1 visual/mechanical and destructive reference footnote 3. Footnote 3 similarly states that for the inspections to be performed for a given population, some examinations for each population. quantity shall be of a nondestructive or destructive variety.

The NEI proposal states [i]nspections and

This is similar to the existing guidance in GALL-SLR.

examinations may consist of any [of] the

The only intended difference is that (demonstrated) following methods (referring to either volumetric NDE techniques could be deployed in lieu of the destructive testing as an option.

visual/mechanical, hardness, nondestructive, or destructive examinations).

The only time a single inspection technique would apply to a population would be if 100% of the population were to be Please provide the basis for going from two inspected by volumetric NDE or destructive examination.

inspections techniques in our current guidance down to one inspection technique.

SL - Staff Question #4 Reliance on One Inspection Technique Detailed Response GALL-SLR Report AMP XI.M33 recommends NUREG-2221 characterizes destructive exams visual/mechanical and destructive as providing quantitative assessments of SL, examinations for each population. while the other techniques (visual/mechanical) are referred to as providing qualitative assessments.

The NEI proposal states [i]nspections and examinations may consist of any [of] the following methods (referring to either Given this characterization, it is proposed that visual/mechanical, hardness, nondestructive, volumetric NDE techniques can be viewed in a or destructive examinations). similar perspective as that of destructive exams as they can provide a measurable or quantifiable extent of wall loss.

Please provide the basis for going from two inspections techniques in our current

Refer to previously cited EPRI Reports guidance down to one inspection technique. on NDE.

SL - Staff Question #4 Current XI.M33 Proposed XI.M33

SL - Staff Question #5 Samples Based on Consequence Response Summary When using the risk-informed Susceptibility to selective leaching is considered in a qualitative manner to provide input into the process along sampling methodology, inspections with consequence information.

focus on consequence not risk (i.e.,

This is included to provide better insight into high/low the product of susceptibility and consequence impacts and to avoid overly conservative consequence). assessment of the SSC population.

The consequence information is still available, such that the susceptibility is not unduly driving decisions on Is susceptibility to selective leaching inspection focus.

considered while using this Based on engineering and research insights, considering methodology?

susceptibility and loss of intended function for the SSC would provide a more complete picture of the inspection focus (along with consequence).

SL - Staff Question #5 Samples Based on Consequence Detailed Response When using the risk-informed Current aging management guidance from the GALL-SLR takes into consideration only likelihood of / susceptibility to selective sampling methodology, inspections leaching for in-scope SSCs when determining sample selection.

focus on consequence not risk (i.e., For selective leaching there has been a limited understanding of the product of susceptibility and material and environmental susceptibility factors that lead to the inception and/or progression of selective leaching hence, the consequence). likelihood of occurrence.

The pilots and research performed indicate an approach that leverages risk insights to sample selection can be implemented Is susceptibility to selective leaching that includes consideration of both likelihood and/or consequence of failures.

considered while using this methodology? The approach allows for conservative decisions to be made that do not over-rely on risk results (risk-based) nor give undue credit to qualitative susceptibility attributes.

The framework does not discount consequence-based information, which are included in the framework, with a rationale for the appropriateness/basis of its inclusion.

SL - Staff Question #5 Samples Based on Consequence Detailed Response When using the risk-informed The attributes used to consider susceptibility to selective leaching, the scoring used, and the criteria for sampling methodology, inspections high/medium/low likelihood results are provided in the EPRI document.

focus on consequence not risk (i.e.,

the product of susceptibility and Susceptibility to selective leaching is used to place all consequence). SSCs on the risk matrix- which is the key output of the risk insights framework The placement of SSCs on the risk matrix is then used Is susceptibility to selective leaching directly to determine not only sampling for inspections, but most importantly, to determine the ideal aging management considered while using this strategies for in-scope SSCs.

methodology?

Susceptibility to selective leaching is specifically referenced in the definition of a surrogate component, which can be inspected in lieu of higher consequence components.

SL - Staff Question #5 Samples Based on Consequence Detailed Response When using the risk-informed Additional precedent from NRC-approved RI-categorization methodologies.

For RI-repair / replacement (RI-RRA) and 10CFR50.69 purposes, plants are sampling methodology, inspections using essentially the consequence portion of the RI-ISI methodology contained focus on consequence not risk (i.e.,

in TR-112657, REV B-A.

As such, this is a consequence-based approach to pressure boundary the product of susceptibility and categorization rather than a pure risk approach.

consequence).

The rationale behind this change in approach was that RI-RRA and 10CFR50.69 can be applied to many different pressure boundary component types and possibly subjected to a wide spectrum of degradation mechanisms,.

This conservative approach to component categorization (i.e. failure probability of 1.0) also provided a more streamlined (i.e. less costly) categorization Is susceptibility to selective leaching process.

considered while using this

In contrast, this change is focused solely on the selective leaching mechanism.

methodology?

Substantial work was undertaken to understand this mechanism and the attributes necessary for this mechanism to be operative in pressure boundary components that are within the scope of LR/SLR AMP programs.

As such, coupling of these two separate and independent evaluations (i.e.

consequence of failure equal to 1.0, failure potential due selective leakage) is consistent with previously NRC RI-applications and provides a more informed approach to AMP for the selective leaching mechanism

SL - Staff Question #6 Removal of Prescriptive Corrective Actions Response The corrective actions program element of The Corrective Action Program is a well-AMP XI.M33 (with the issuance of GALL-SLR) established and regulated program at the was revised to include specific utilities.

recommendations for conducting extent of condition examinations when acceptance criteria are not met. The proposed change credits the Corrective Action Program to determine the appropriate causal analysis, extent of condition, extent of This is consistent with several other GALL- cause, etc., commensurate with safety SLR Report AMPs. significance of the identified issue.

The NEI document proposes deleting this This proposed change cross-cuts several language, please provide a technical basis for AMPs.

this change.

Inaccessible Power Cables Not Subject to 10 CFR 50.49 Environmental Qualification Requirements

Cables - Staff Question #1 Duration between testing Response Please specify a duration between Cables should be tested on a 6-year testing for the provision have been frequency and two consecutive good tested at least twice in the good test are required to extend to a 10-range (is this once -6 years prior to year frequency.

entering the period of extended operation and once more when entering the period of extended The two consecutive tests can occur operation?). anytime prior to or during the PEO.

Do the test results need to be tested in the good range twice consecutively?

Cables - Staff Question #2 Insulation type and moisture effects Response Certain cable types have more operating Which insulation type(s) does not have experience of cable failures (e.g., XLPE, a compact EPR design, and black EPRs). However, an operating experience of good cable since the industry adoption of the VLF tan delta failures due to significant moisture test method there have been no known industry OE for any cable type that suggests failures soon effects? after a good tan delta test as a common occurrence.

Cable insulations that have a higher number of failure OEs was considered in the XI.E3 RIAM pilot. Each insulation type has different characteristics when exposed to water or other adverse environments. This was accounted for in development of the likelihood table. For instance, XLPE, butyl rubber, and compact insulation were weighted higher because they are more susceptible to long-term, water-related degradation mechanisms compared to pink/brown EPR or tree-resistance XLPE.

Cables - Staff Question #3 Data Trending Response NEI is proposing to increase the EPRI PMBD vulnerability study indicates no increased failure rate for cables unless the test frequency is > a 10-year test period.

testing frequency by approximately EPRI review of industry test data since 2009 had no instances of long-66% using two relatively undefined term wetted cables failing when tested on a 6-year frequency, and very cables that tested good did not test less than good on subsequent data points. tests.

The test data points are very well defined by three different acceptance criteria (3002000557) each time the cable is tested. The acceptance criteria is based on an expert solicitation (1021070) and validated by Explain how using only two data EPRI review of industry test data between 2009-2015 (3002005321, 1025262).

points can establish a meaningful It is not just two data points that establish the trend, but every tests of a trend to inform changes to testing particular cable insulation type at each plant that uses that insulation are used to establish the health of a particular insulation type. When frequency. combined with industry OE shared via the EPRI Cable User Group provided input into the weighting factors in the Cable Pilot study.

Using two consecutive tests helps to ensure the cable remains in good condition over a longer period. This helps to better understand the cable characteristics and responses in the installed environment prior to considering extending the monitoring frequency.

If the test frequency is extended to a 10 years, if any subsequent test results suggests additional degradation is occurring, then accelerated test frequency or corrective action should be pursued accordingly based on the severity of the results.

Electrical Slides Back-up Information EPRI Preventive Maintenance Basis EPRI Report 3002000557 VLF Tan EPRI Report 3002005321 breakdown Database Vulnerability Result Delta Acceptance Criteria for Various of cable issues for cables evaluated Insulation types between 2009-2015

Next Steps Additional Review of Technical Supporting Documents (?)

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