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K. Voelsing - Risk
	ML26023A078
Person / Time
Site:	Nuclear Energy Institute
Issue date:	07/29/2025
From:	Voelsing K; Nuclear Energy Institute
To:	Thomas Scarbrough; NRC/NRR/DEX/EMIB
References
	Download: ML26023A078 (0)
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©2025 Nuclear Energy Institute 2 10 CFR 50.69 Risk Informed Categorization and Treatment of SSCs RISC = Risk Informed Safety Classification Classify SSCs not only as safety-related or non-safety-related, but also based on their actual safety significance For low-safety significance SSCs (i.e.

RISC-3) allow alternative treatment in lieu of the Special Treatment requirements in these programs

Modernizing Regulatory Frameworks -

becoming more risk-informed and performance-based Reducing Regulatory Burden -

reducing unnecessary regulatory requirements, and streamlining through the adoption of advanced technologies Modernizing Regulatory Frameworks

4%

17%

9%

50.69 LAR Approved 50.69 LAR Submitted 50.69 LAR Planned No near term plans 50.69 License Amendments Risk Informed Categorization and Treatment of SSCs US FLEET ADOPTION OF 50.69 10 CFR 50.69 LAR approves the categorization PROCESS Methods to be used to address Internal Events, Fire, Seismic, Other External Hazards, and Passive Categorization must all be described Once approved, when to perform categorization and/or apply alternative treatments is up to the licensee

©2025 Nuclear Energy Institute 7 50.69 Categorization Process Simplified Flowchart Integrated Decision-making Panel (IDP) is a critical part of the categorization process, and makes final determinations Many checks in the process assure that all potential impacts are considered (e.g., failure of a passive function impact on active function, SSCs that touch multiple systems, etc.)

8 Example Final Categorization Example categorization table

©2025 Nuclear Energy Institute 10 50.69 Alternative Treatments 10 CFR 50.69 (d) - Alternative Treatment Requirements RISC-3 The licensee or applicant shall ensure, with reasonable confidence, that RISC-3 SSCs remain capable of performing their safety-related functions under design basis conditions, including seismic conditions and environmental conditions and effects throughout their service life. The treatment of RISC-3 SSCs must be consistent with the categorization process. Inspection and testing, and corrective action shall be provided for RISC-3 SSCs.

i.

Inspection and testing. Periodic inspection and testing activities must be conducted to determine that RISC-3 SSCs will remain capable of performing their safety-related functions under design basis conditions; and ii.

Corrective action. Conditions that would prevent a RISC-3 SSC from performing its safety-related functions under design basis conditions must be corrected in a timely manner. For significant conditions adverse to quality, measures must be taken to provide reasonable confidence that the cause of the condition is determined and corrective action taken to preclude repetition.

Alternative Treatments (ATs) do NOT:

Change the required design function Change Technical Specification (TS) requirements Note: TSTF-596 addresses administrative reference to IST Program Degrade the performance or reliability of the SSC

Alternative Treatment Development Considerations How is the component currently treated?

What is the components design function?

What does the OE and equipment performance tell you?

What inspections, tests, or monitoring should stay in place?

What can be relaxed?

11 How do we maintain, with reasonable confidence, the ability of the SSC to perform its design function under design basis conditions throughout its service life?

12 50.69 Alternative Treatment Examples Practical Alternative Treatment Examples for RISC-3 Components Extending the service life of environmentally qualified components by evaluating margins and other sources of conservatisms Reducing the frequency of tests by taking credit for performance history and other means of fault-finding (e.g., quarterly mini flow test have identified performance anomalies that do not show up during an outage flow full test)

Eliminating or reducing required testing by crediting other monitoring means (e.g., operator walkdowns in lieu of ASME Section XI pressure test to look for pressure boundary leakage)

Reducing Maintenance Rule scope for LSS components by crediting the corrective action process and periodic reviews for continuous monitoring Appendix J leakage testing for the RISC-3 SSCs could be credited through normal operational manipulations which demonstrate acceptable leak tightness (i.e., no leakage past closed isolation valves during operational evolutions)

©2025 Nuclear Energy Institute 13 LAR Process Categorization Alternative Treatments Monitoring 50.69 Benefits Within the scope of 50.69, the licensee determines appropriate ATs Licensees utilize a robust evaluation process considering many factors to select ATs that provide reasonable confidence that the SSC will continue to perform its design function under required conditions ATs do not change the required function of the SSC, nor any Tech Spec requirements for that SSC 10 CFR 50.69 ATs Key Takeaways

Feedback and Process Adjustment (at least every 2 cycles)

Using data from testing and inspection activities, adverse changes in performance can be detected and are compared to the unreliability assumed in the categorization process

Periodic reviews consider:

Plant modifications

Operational or regulatory changes

Plant and industry Operating Experience (via corrective action)

Updated risk information and sensitivities based on PRA model updates 50.69 Categorization and Alternative Treatments are updated, as required, based on plant changes and component performance.

50.69 Performance Monitoring

50.69 inspection and testing, along with these programs and processes, that remain in effect provide high confidence that unknown degradation of LSS items is not occurring Performance Monitoring - Examples of Monitoring Many existing site programs remain in place in addition to the inspection, testing, and review processes required by 50.69:

License Renewal Aging Management Plans (AMPs)

Flow Accelerated Corrosion (FAC)

Raw Water Program

Buried Pipe Program

Boric Acid Corrosion

Technical Specifications

Corrective Action Program

Design Change

10 CFR 50.59

Operating Experience 16

Maintain the safety-related function of the component

Provide the flexibility to focus on the right work at the right time

Increased cost-savings does not mean that safety is decreasing; risk-informed processes are proven to increase both safety and efficiency

Developing Alternative Treatments for RISC-3 MOVs 50.69 Benefits Example Case 1

After each system is categorized, Constellation evaluates potential ATs Constellation developed a fleet procedure for evaluating RISC-3 MOVs for alternative treatment.

This procedure described a process like the one outlined in BWROG Document:

TP20-3-396 - 10CFR50.69 Alternative Treatment Plan Guidance for RISC-3 Motor Operated Valves Programmatic Approach to 50.69 Alternative Treatments for MOVs 20 Outline of MOV Alternative Treatment Plan Guidance

1. Develop MOV Functional Groups (FGs)

Valve Type, Size, Model, and Stem Configuration (diameter, pitch, lead)

Actuator Type and Gear Ratio Motor Type (AC/DC) and Size Application and Service Conditions (e.g., flow, temperature, duty cycle)

2. Develop MOV Alternative Treatment Plans Functional Margin Design Basis Coefficient of Friction (DBCOF)

Lubrication quality Ambient and service environment Degradation trends

3. Identify Representative MOVs Lowest Functional Margin Evidence of Degrading Trends High-stress service conditions

4. Perform Task Execution and Trend Evaluation Stem nut wear Diagnostic trace anomalies Motor current/contact dropout time changes Lubrication conditions Functional margin drift Scope expansion as needed

Evaluated Potential PM Changes MOV Functional/Peer Group Characteristics Performance History

- Individual MOV performance Performance information for MOV Functional/Peer Group EPRIs Preventive Maintenance Basis Database (PMBD) evaluation

- Relevant failure modes Potential impact of any changes/extensions Overall impact of any conservative estimates of probability of failure Example

MOV Valve Group Containmnent Atmospheric Control (CAC) MOVs 8 - non-critical, low duty cycle, mild conditions 7 - non-critical, high duty cycle, mild conditions

Changes implemented PM frequency for Limitorque inspections increased from every 8 years to 16 years Additional PM created to ensure stem lubrication continued to be completed on 8-10 year interval

Inspection and Testing New PMs also created to complete inspection / diagnostic testing on representative valves in this MOV Valve Group

Corrective Action Continue to apply Corrective Action, Trending, etc. as required by plant processes and 50.69 21 MOVs - Evaluated for PM Test Frequency Extensions

No change in design function FMEA considerations show extension of PM has insignificant impact on potential of failure Provides inspection and testing each group of valves and high confidence that any adverse performance trends would be identified All impacted valves would have negligent safety impact event if they did fail Potential savings of $500K+ per plant

- Assumes plant operation through subsequent license renewal (SLR)

- Conservative estimate of number of MOVs per plant 22 MOVs - Evaluated for PM Test Frequency Extensions

Resolving a Degraded Condition Involving Two MOVs Utilizing 10 CFR 50.69 50.69 Benefits Example Case 2

24 Main Steam Line Shutoff Valves 50.69 Safety Benefits Valve description:

Valves located in each Main Steam line, downstream of the outboard Main Steam Isolation Valves (MSIVs)

Isolate main steam and assist in eliminating any leakage through the MSIVs after a postulated accident Manually opened, closed from the Main Control Room 24 gate valves, manufactured by Velan with Limitorque actuators Issue:

During RFO23, excessive seat leakage identified for 2 valves (B and C Main Steam Line Shutoff Valves)

Leakage exceeded the levels specific in Technical Specifications (TS) for the Main Steam Positive Leakage Control System" (MSPLCS). This would prevent restart.

25 Main Steam Line Shutoff Valves 50.69 Safety Benefits Repair Options

Replace the valves with new, safety-related valves Estimated cost >$700,000 per valve

Replace the impacted parts to repair the actuator Gear ratio change to increase closing thrust and reduce leakage No safety-related parts available in the industry Lead time from vendor to obtain safety-related parts >1 year Increased flexibility provided by 50.69

Valves/Parts had been categorized as RISC-3

Like-for-like non-safety related replacement parts (pinion and gear/worm shaft and soft clutch)

Available for immediate delivery Cost of replacement part $15K per valve Procured under like-for-like process Exact same part (form/fit/function)

Just not available as safety-related

Parts delivered, valves repaired, seat leakage returned to acceptable levels

Faster restoration of degraded condition, resulting in better equipment reliability 50.69 Benefits Main Steam Line Shutoff valves restored

>1 year faster than available safety-related parts Savings of more than

$1.35M just on these two parts NO change in function as these were like-for-like replacements

IST Interval Update 50.69 Benefits and Value Example Case 3

Supplemental Position Indication (SPI)

§ 50.55a(b)(3)(xi) licensees shall verify that valve operation is accurately indicated by supplementing valve-position indicating lights with other indications, such as flow meters or other suitable instrumentation

Requirement introduced in 2017 through 10 CFR 50.55a conditions on endorsement of 2012 ASME OM code version

Requirement to assess and document this requirement now impacting licensees as they perform their next code/interval updates

What is required Observe and record supplemental valve position verification (SPV) to assure valve obturator and remote indication accuracy.

Use flowmeters or other suitable instrumentation to verify obturator positioning (observations need not be concurrent)

An estimated 70-80% of the necessary actions to verify obturator positioning is already being performed as a function of directed procedure requirement or implied proper operation of systems observable by achieving system metrics and satisfactory surveillance results.

The missing required action is the conscious observation and recording of the required supplemental position verification to comply with the code What is Required for Each Valve

Impact Assessment For a 2-unit site implementing its next OM Code interval update in Jan 2026 Without 50.69:

- 1496 IST components with new code requirements for interval update

- 5274 unique IST test requirements

- Most significant and impactful requirement is the addition of the required Supplemental Position Indication (SPI) verification introduced through 10 CFR 50.55a conditions With 50.69,

- For this site many systems* have already been categorized and many of these valves are RISC-3

- RISC-3 SSCs can have Alternative Treatments (ATs) evaluated and applied in lieu of IST** Special Treatments

- 463 IST components with new code requirements for interval update (69% reduction)

- 2065 unique IST test requirements for these components (61% reduction)

- TS requirements are not impacted by 50.69, See previous discussion of TSTF-596 impacts

Systems categorized under 10 CFR 50.69 for this site include:

Nuclear Boiler / Main Steam Control Rod Drive Radiation Monitoring Emergency Diesel Generators Condensate Transfer Plant Service Water RHR / RHRSW Drywell Cooling & Drywell Chilled Water Containment Purge, Vent,

& Nitrogen Inerting HPCI RCIC (in progress)

H2O2 Analyzers (in progress)

Drywell Pneumatics (in progress)

Standby Liquid Control (in progress)

Standby Gas Treatment (in progress)

Recirc (in progress) 29

Thank you

ML26023A078

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