Nuclear Power Reactors – An Example of Improvements in Reliability and Potential for Improvement Dr. Jess Gehin Director, Consortium for Advanced Simulation of Light Water Reactors Oak Ridge National Laboratory 5th Accelerator Reliability Workshop (ARW 2015) Knoxville, Tennessee April 26 to May 1, 2015
34
Embed
Nuclear Power Reactors An Example of Improvements in ... - Gehin... · Reliability of Nuclear Power Plants •Reliability – A measure of plants expected generation when expected
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
Nuclear Power Reactors – An Example of Improvements in
Reliability and Potential for Improvement
Dr. Jess Gehin Director, Consortium for Advanced Simulation
Most Schedules Delayed Because Scale Back in Planned Construction
7 7 7 7
Availability and Reliability of Commercial Reactors
• Utilities require high availability and capacity factors for nuclear power plants – Availability Factor – fraction of the of time a reactor is able to produce
electricity
– Capacity Factor – ratio of the actual energy output to the potential output
• Desire for high capacity factors is driven by: – Large capital costs for nuclear plants
– Large cost of replacement power when the plant is shutdown
– Very low production costs compared to other sources
• Factors that affect Availability/Capacity – Planned refueling outages
– Unplanned shutdowns due to mechanical failures or offsite issues
– Major outages for maintenance, upgrades, component replacements
8 8 8 8
Nuclear Energy Has a High Capacity Factor Compared to
Other Energy Sources
Source: NEI, updated 4/14
9 9 9 9
Capacity Factors Have Increased Significantly
2014 Capacity Factor 91%
Source: NEI, updated 4/14
10 10 10 10
The US Nuclear Fleet as a Whole is Performing Well
Source: NEI, updated 4/14
11 11 11 11
Improvements in Capacity Factors Largely Driven by Optimization of Refueling
Outages
Outages are planned for spring/fall – time of low demand
Source: NEI, updated 4/14
12 12 12 12
Significant Power has Been Added Through Uprates
Plant power uprates range from 1 – 20%
Source: NEI, updated 4/14
13 13 13 13
Reliability of Nuclear Power Plants
• Reliability – A measure of plants expected generation when expected to be available.
• Scheduled Outage - The shutdown of a generating unit, transmission line, or other facility for inspection, maintenance, or refueling, which is scheduled well in advance (even if the schedule changes)
• Forced Outage - The shutdown of a generating unit, transmission line, or other facility for emergency reasons, or a condition in which the equipment is unavailable as a result of an unanticipated breakdown. – An outage is considered "forced" if it could not reasonably be delayed beyond 48 hours from
identification of the problem, if there had been a strong commercial desire to do so. In particular, the following problems may result in forced outages
– Any failure of mechanical, fuel handling, or electrical equipment or controls within the generator's ownership or direct responsibility (i.e., from the point the generator is responsible for the fuel through to the electrical connection point)
– A failure of a mine or fuel transport system dedicated to that power station with a resulting fuel shortage that cannot be economically managed
– Inadvertent or operator error
– Limitations caused by fuel quality
14 14 14 14
Several Performance Indicators are used
• U.S. NRC (primarily safety focused, but informs on reliability): – Automatic Reactor Scrams While Critical (IE)
• Axial and azimuthal CRUD deposition patterns were consistent with plant data
Now Integrating Chemistry as Subgrid Model in CFD
• CRUD deposition simulated directly on fuel rod surfaces.
• Will be applied for subregion of core using CIPS calculation of power history
32 32 32 32
Technology Deployment We have now deployed 3 Test Stands
• Early deployment to industry for rapid and enhanced testing, use, and ultimate adoption of VERA to support real-world LWR applications Westinghouse (Mar 2013): Test VERA core
simulator’s ability to analyze AP1000 first core startup
EPRI (Nov 2013): Benchmark VERA fuel performance (Peregrine) on PCI applications utilizing new EPRI’s computing platform
TVA (Mar 2014): Test VERA CFD capability (Hydra-TH) on lower plenum flow anomaly observed in operational reactors
• CASL Test Stands have exposed technology gaps, deployment needs, and driven continuous improvement Have become a best practice for us
• More Test Stands on the horizon
33 33 33 33
Conclusions
• Because of economic and safety drivers reliable operation of nuclear plants is essential.
• The nuclear industry has continually improved operation of their plants over time as well.
• Nuclear fuel reliability has also significantly improved resulting in reduce down time and replacement fuel costs
• On-going research has the potential to support continual improvements.