Increase Operational Flexibility of Pressure Boundary Components Using an Enhanced Risk‑Informed Categorization Methodology - MTA-PRA-001

Administrative Items
Date	12/15/2020
Functional Area Where Benefits Will Be Realized	Probabilistic Risk Analysis Licensing and Regulatory Affairs
Reference Implementation Guidance	Enhanced Risk‑Informed Categorization Methodology for Pressure Boundary Components (EPRI 3002015999) Development of a Comprehensive Risk‑Informed Methodology for Pressure Boundary Components (EPRI 3002013139)
Industry SME	EPRI – Patrick O’Regan Contact: NuclearPlantMod@epri.com
Previous Implementation	Please contact EPRI for implementation examples and contacts.
Implementation Enablers	N/A
SWEEP Score	Cost – Level 3 – Implementation cost is less than $1 million per site. Savings – Level 0 – Savings are not evaluated because the process improvement is an enabler, which does not inherently produce cost savings but permits implementation of other improvements. Payback – Level 0 – Because the enhanced methodology is a process enabler, payback will only be realized through successful implementation of the 10 CFR 50.69 program, which is dependent on the cost‑saving measures taken and the lifetime of the facility. Licensing Readiness – Level 3 – No changes are required for implementation. Applicable licensee interactions with the plant’s respective regulator may be required. The effort to gain NRC endorsement is currently underway. Technology Readiness – Level 3 – The methodology is developed and has been implemented at some nuclear plants. Once NRC approval is received, the methodology is ready for wide operational deployment. Implementation guidance and lessons learned will be captured in the updated EPRI report 3002015999. Implementation Proficiency – Level 3 – The methodology can be implemented by all sites regardless of digital experience.
Applicability	All reactor types The 10 CFR 50.69 process is an NRC approved rule.
Keywords	Risk-informed categorization; 10 CFR 50.69; pressure boundary components; safety significance
Business Case Analysis Cross-Reference	N/A

Description

The NRC’s 10 CFR 50.69 process allows a plant to categorize the safety significance of its structures, systems, and components (SSCs) using a robust categorization process defined in NEI 00‑04, 10 CFR 50.69 SSC Categorization Guideline, as endorsed by NRC in Regulatory Guide 1.201. Recent industry experience and understanding of the existing methodology for categorizing pressure boundary components suggests that it requires substantial resources and produces overly conservative results. As a result, an enhanced risk‑informed categorization methodology for pressure boundary components as described in EPRI reports 3002013139 and 3002015999 has been developed to assist in streamlining the categorization process. This enhanced methodology provides for a full plant evaluation of all safety‑related and non‑safety‑related systems to determine if the pressure boundary components are of high safety significance (HSS) or low safety significance (LSS). Note that use of either methodology is only applicable for plants that already have an approved license amendment request (LAR) for implementation of a 10 CFR 50.69 program. This enhanced methodology is cost effective and stable because it requires a one‑time evaluation and minor changes to inputs will have minimal or no impact on the categorization results.

Benefits

Benefits Estimate

Level 0 – Savings are not evaluated because the process improvement is an enabler, which does not inherently produce cost savings but permits implementation of other improvements.

Benefits Description

Implementation of an enhanced risk-informed categorization methodology for pressure boundary components enables efficient implementation of 10 CFR 50.69 which can result in savings through:

• Reduction in overall cost of the implementation of a 10 CFR 50.69 program because the methodology requires a one‑time full plant evaluation instead of a system‑by‑system evaluation. Based on experience, these system‑by‑system evaluations cost approximately $20,000 to $40,000 per system.
• Increased operational flexibility of pressure boundary components by focusing attention on the components that are the most important to plant safety.
• Improved ability to implement cost reductions on LSS components by reducing time spent on categorization and allowing for more long‑term planning.
• Improved plant safety by identifying all risk‑informed safety classification (RISC)‑2 components upfront, reducing the need to evaluate each component on a system‑by‑system basis.
• Increased stability to the overall categorization process by defining prerequisites and predetermined HSS systems so that minor changes will have minimal to no impact on the categorization results during periodic updates.

Costs and Schedule

Cost

Level 3 – Implementation cost is less than $1 million per site.

Schedule

Less than six months.

Scope Context

Per site. Cost does not include the efforts associated with obtaining an approved LAR for implementation of a 10 CFR 50.69 program.

To maximize the potential cost savings, the following prerequisites should be met before implementing this categorization methodology:

• The plant has a robust internal events probabilistic risk assessment model including internal flooding.
• The plant has a robust program for addressing localized corrosion, flow‑accelerated corrosion, and erosion.
• The plant’s protective measures for internal flooding events are not categorized as LSS.

Risks

No unique risks beyond standard project risks associated with implementing changes at nuclear power plants.