Streamline your refueling sequences, shorten your outages, and make shuffling plan design straightforward with a cost-effective, user-friendly tool
Your challenges as a fuel shuffling plan designer
Shortening refueling outages is crucial to maximize the availability factor of nuclear power plants. Fuel assembly shuffling and (re)loading are among the most time-consuming tasks during an outage. They usually lie on the critical path for reactors that use an in-core shuffling strategy. Each step of the shuffling sequence must comply with a number of safety and logistic constraints, such as ensuring sufficient shutdown margin. Besides, a good shuffling sequence is often a moving target due to changes in maintenance work requirements. A shuffling optimization tool is therefore a must to reduce outage costs and (pre-outage) shuffling plan development time.
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More information about SOSA?
Pieter Wakker
Team Manager Fuel Management Services
Our solution: SOSA
SOSA (Shuffling Optimization by Simulated Annealing) is NRG’s in-house developed software to optimize in-core fuel shuffling and reloading of Pressurized Water Reactors (PWR) and Boiling Water Reactors (BWR). The program optimizes the sequence of refueling machine steps to move from the loading pattern of the latest cycle to the one of the next cycle. The number of steps and the average step duration are minimized while complying with a wide range of constraints, such as shutdown margin, control blade support (in BWRs), fuel assembly support (in PWRs), and the number of empty core locations around a detector.
Proven benefits of using SOSA versus manual shuffling plan development:
typically 4- to 14-hour savings
of fuel assemblies and inserts (on average 5 to 10% less)
for reactor engineers (few hours instead of few days or weeks)
SOSA’s features in a nutshell
- Shuffling sequence optimization
SOSA can currently design an optimal full- or quadrant-core shuffling plan for up to 12 optimization parameters and 23 constraints at the same time. The code is set up in such a way that new optimization parameters and plant-specific constraints can be easily implemented upon users’ request.
- Maintenance staging
SOSA phases the shuffling plan to accommodate maintenance work and fuel assembly inspection. The core is first shuffled or off-loaded to the maintenance configuration and eventually reshuffled to the loading pattern of the new cycle. The user can define a broad set of maintenance and inspection tasks to account for in the plan, such as replacement of components and leaker sipping.
- Spent fuel pool optimization
SOSA also optimizes the position of the fuel assemblies in the spent fuel pool. Compliance with placement restrictions based on cooling time and reactivity is thus effortlessly ensured. This greatly simplifies pool management in plants with nearly full, highly constrained pools.
- Outage monitoring
Last but not least, SOSA enables the outage staff to easily follow the progress of refueling by showing on its graphical user interface which fuel assemblies still have to be moved and estimating the time needed to conclude the shuffling sequence. SOSA is therefore a valuable tool not only for reactor engineers, but also for outage personnel.
- Graphical User Interface (GUI)
SOSA runs on Windows and has a user-friendly, fully interactive GUI.
SOSA Customers
Team Fuel Management Services
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