Improved Thermal Performance Through Cycle Isolation Monitoring - MTA-EN-007
| Administrative Items | |
|---|---|
| Date | 12/14/21 |
| Functional Area Where Benefits Will Be Realized | Engineering
Operations Maintenance |
| Reference Implementation Guidance | Plant Engineering: Thermal Performance Engineering Handbook, Volume 2 (EPRI 3002000489) |
| Industry SME | EPRI PRR
Contact: NuclearPlantMod@epri.com |
| Previous Implementation | This improvement has been implemented at several nuclear plants. Please contact the EPRI SME for additional information. |
| Implementation Enablers | If wireless sensors are implemented, a wireless network infrastructure is needed to support the sensors.
|
| Applicability | All reactor types
All geographic regions |
| Keywords | Cycle isolation; cycle isolation monitoring; thermal performance; valve leaks; valve repair; power recovery |
| Business Case Analysis Cross-Reference | Plant Modernization Business Case‑Improved Thermal Performance Through Cycle Isolation Monitoring: Cost‑Benefit Analysis of Cycle Isolation Monitoring for Addressing Valve Repairs That Lead to Lost MWe (EPRI 3002019844). |
Description
Cycle isolation is the process of recapturing lost power by minimizing the steam and heated water flow paths that bypass all or part of the turbine cycle. High‑enthalpy leaks to the condenser are a major concern and are often not visually identifiable. Isolation valves, such as turbine bypass valves and main steam line drain valves, and air‑operated valves (AOVs) used for level and flow control in the heat cycle may be potential isolation leakage paths that result in lost power.
A cycle isolation monitoring program uses installed or wireless instrumentation or manual measurements to monitor and identify leaks caused by damaged valves. To implement a cycle isolation monitoring program, a population of valves are identified based on impact on the cycle and outfitted with instrumentation typically focused on temperature measurements (e.g., resistance temperature detectors or thermocouples) or flow measurements (e.g., acoustic sensors). Nuclear plants typically experience losses of around 1‑6 MWe per unit per year due to valve leakage. These losses are recoverable after leaks are identified and repairs are prioritized through cycle isolation monitoring. The initial benefits of a cycle isolation monitoring program materialize in the first two years of implementation. Cost savings benefits are highly sensitive to the unit capacity of the plant and the price of power. As the program matures and valves have been repaired, lost MWe will decrease along with potential for MWe recovery.
Cycle isolation monitoring software can also be purchased from a vendor or developed in‑house to automate identification and MWe quantification of leaking valves. Implementation of the software provides more efficient identification of leaking valves and improves workload efficiency but is not required. Wireless sensors may also be installed to improve data quality and workload efficiency, but permanently wired sensors can also be used for a successful cycle isolation monitoring program.
Benefits
Benefits Estimate
Level 1 – Savings are less than $1 million per year, per unit. Estimated savings range from approximately $100K‑$800K (0.5 MWe – 6 MWe recovered) per year, per unit with the greatest savings seen in the first couple of years of implementation. Savings are also sensitive to the unit capacity and power pricing at the plant.
Benefits Description
- Increased plant output due to repaired valve leaks identified through cycle isolation monitoring
- Increased maintenance planning efficiency by identifying valve leaks early on
- Reduction in maintenance costs due to potential decrease in pipe cavitation erosion by identifying and repairing leaks
- Reduction in labor hours associated with walkdowns for valve measurements through installation of sensors
- Reduction in labor hours associated with data analysis through installation of cycle isolation software
Costs and Schedule
Cost
Level 3 – Implementation cost is less than $1 million per unit. Costs range from approximately $150K‑$350K for implementation of wireless sensors and cycle isolation software, but wireless sensors and software are not necessary to implement a cycle isolation monitoring program. Ongoing annual maintenance costs for the sensors and software range from approximately $10K‑$30K per year.
Schedule
One to three years per unit, which includes planning, procurement, and implementation.
Scope Context
Per unit
Risks
For BWRs, there is a need to shield when installing and maintaining cycle isolation monitoring instrumentation and when performing valve repairs to reduce risk of personnel exposure to radioactivity.
SWEEP Score
| Category | Level | Description |
|---|---|---|
| Cost | 3 | Implementation cost is less than $1 million per unit. Costs range from approximately $150K‑$350K for implementation of wireless sensors and cycle isolation software, but wireless sensors and software are not necessary to implement a cycle isolation monitoring program. Ongoing annual maintenance costs for the sensors and software range from approximately |
| Savings | 1 | Savings are less than $1 million per year, per unit. Estimated savings range from approximately $100K‑$800K (0.5 MWe–6 MWe recovered) per year, per unit with the greatest savings seen in the first couple of years of implementation. Savings are also sensitive to the unit capacity and power pricing at the plant. |
| Payback | 2 | Payback period is greater than one year but less than five years. Payback period is driven by the timing of the refuel cycle when valves are repaired. |
| Licensing Readiness | 3 | This technology has already been implemented at nuclear sites and is ready for wide operational deployment. |
| Technology Readiness | 3 | No changes are required for implementation. |
| Implementation Proficiency | 3 | The technology can be implemented by all sites, regardless of digital experience. If wireless sensors are pursued, implementation proficiency is dependent on site‑specific experience related to wireless data infrastructure, wireless data transmission for maintenance and monitoring, and cyber‑security protocols. |