Reduce Maintenance Costs and Improve Plant Reliability by Implementing a Full Solid-State Protection System (SSPS) Hardware Refresh - MTA-MA-023

Administrative Items
Date	12/15/2020
Functional Area Where Benefits Will Be Realized	Maintenance Operations Engineering
Reference Implementation Guidance	2020 TIP Award Submittal #11; Solid State Protection System (SSPS) Refresh Project (ID: 13347539)
Industry SME	EPRI – Matt Gibson Contact: NuclearPlantMod@epri.com
Previous Implementation	Please contact EPRI for implementation examples and contacts.
Implementation Enablers	N/A
SWEEP Score	Cost – Level 1 – Implementation cost is greater than $5 million. Refresh of the full system hardware results in a larger upfront cost than as‑needed repairs, but extends the life of the system for another 20‑30 years. In comparison, replacing obsolete components as they fail could result in a failure rate that would eventually increase beyond the ability to keep up with replacements. Also, the overall system refresh cost is approximately 4‑6 times less than a full system replacement. Savings – Level 1 – Savings are less than $1 million per year per unit. For one example plant, savings due to reduction in maintenance and operation costs were estimated at $7 million to $8 million per unit for the remainder of plant life ($14 M – $16 M for dual‑unit site). Significantly greater cost savings could be realized through avoidance of inadvertent reactor trips. Payback – Level 1 – Payback period will vary based on plant‑specific circumstances and may be greater than five years. Payback period may be shorter depending on the number of avoided reactor trips. Licensing Readiness – Level 3 – No changes are required for implementation. Licensing is performed under 10 CFR 50.59 and does not require a License Amendment Request (LAR). Technology Readiness – Level 3 – This technology is ready for wide operational deployment. Implementation Proficiency – Level 2 – A systematic engineering approach should be taken when performing a full refresh of the SSPS, especially if integrating digital technologies.
Applicability	Westinghouse PWR with SSPS or Relay Protection System All geographic regions
Keywords	Solid state protection system; SSPS; system refresh; reduced maintenance; lifecycle
Business Case Analysis Cross-Reference	N/A

Description

The Solid‑State Protection System (SSPS) is a safety‑related system that supplies reactor trip signals and actuates engineered safety features (ESFs) during all normal operating and accident conditions. Sensors both inside and outside plant containment provide signals either directly to the SSPS or through the Reactor Protection System to the SSPS. Many plants still have the original SSPS installed and are challenged by age‑related degradation and component failures. Replacing components as they fail addresses the immediate issue but can drive up maintenance costs over time and limit system availability. A system refresh using equivalent components with upgraded designs can be performed to increase system reliability and extend the overall lifecycle. Working with the OEM, all components, including logic boards, card cage, relays, power supplies, and test panels can be refreshed with new hardware making use of the existing architecture. Priority may be given to components with higher failure rates when selecting the equivalent component refreshes. For the purpose of this MTA, a full system refresh is assumed. A benefit of performing a full system refresh is that it can be done under one, large EC instead of several, smaller ECs for multiple refreshes with resultant costs. Taking into account best practices and desired features, additional upgrades can also be implemented such as digital replacement logic boards or installation of additional testing switches. By refreshing the entire system, the lifecycle is reset for another 20‑30 years, decreasing the likelihood of failures and enabling efficient operation and maintenance of the system.

Benefits

Benefits Estimate

Level 1 – Savings are less than $1 million per year per unit. For one example plant, savings due to reduction in maintenance and operation costs were estimated at $7 million to $8 million per unit for the remainder of plant life ($14M – $16M for dual‑unit site). Significantly greater cost savings could be realized through crediting avoidance of inadvertent reactor trips.

Benefits Description

• Reduction in maintenance costs because the lifecycle of the system components is reset and many single‑point vulnerabilities are eliminated.
• Reduction in operations costs from improvements to the system, reducing person‑hours required for system surveillance tests. Note that there are not significant savings in the reduction of Technical Specification required surveillance tests or calibration of bistable inputs.
• Reduction of lost power generation caused by an inadvertent trip due to system component failure or human performance error.
• Licensing is performed under 10 CFR 50.59 and does not require a License Amendment Request (LAR).

Costs and Schedule

Cost

Level 1 – Implementation cost is greater than $5 million. Refresh of the full system hardware results in a larger upfront cost than as‑needed repairs, but extends the life of the system for another 20‑30 years. In comparison, replacing obsolete components as they fail could result in a failure rate that would eventually increase beyond the ability to keep up with replacements. Also, the overall system refresh cost is approximately 4‑6 times less than a full system replacement.

Schedule

More than three years including installation and surveillance test during a refueling outage. Previous implementation at an example two‑unit site took approximately four years for design, procurement, installation, and testing.

Scope Context

Cost and schedule estimates include:

• Hardware specification and design validation
• Hardware build and factory acceptance testing (FAT)
• Site pre‑installation testing
• Installation
• Post‑installation testing and return to operations (RTO)

Risks

Cabinet terminations, which can be in the thousands for a full system refresh, must be verified to preclude potential wiring errors that would result in project delay or malfunction. Coordinating installation verification in a timely manner prior to surveillance testing will help mitigate this risk.

OEM knowledge of the existing SSPS reduces the potential for incorrect operation of the replacement system.