Fuel loading and unloading: a new application for simulation

02 October 2010

Along with REEL, CORYS  is completing the development of its very first fuel loading and unloading simulator. This equipment includes a whole host of innovations: connection to PLCs, a mobile version, 3D imaging and more. 

A virtual addition to the training pool

For many years now, EDF has been training the teams in charge of loading and unloading fuel at the CETIC, a technical expertise centre in Châlons-sur-Saône. In order to master the key procedures, trainees have a pool with a reactor tank, inert fuel assemblies and a loading machine.

The simulator will provide a ‘virtual addition’ to this set-up. By adding the spent fuel pool, transfer system and bridge, it will enable operators and supervisors to interact with the full configuration they work with in power plants.

Another new feature is that three mobile modules will be added to the traditional simulator at the CETIC, providing a complete virtual layout.

This equipment can be moved from one power plant to another for refresher courses just before each refuelling operation. This process takes place once every 18 months on average.

This is too infrequent for the personnel concerned to remember each procedure when the time comes for them to put it into practice - so much so in fact that the employees in question describe this intervention as an ‘activity’ rather than as part of their core job description.

Coordinating movements with millimetre precision - 15 metres underwater

Fuel assembly operations require both excellent mastery of the process and extreme precision. Square bars approximately 25cm thick and 4m long have to be transferred between two buildings, via a mechanical tunnel.

They must be moved without being bumped in the slightest, and slid into place with millimetre precision once they arrive at their destination. To complicate matters still further, these operations take place 15 metres under water, and spent bars are still very hot - several hundred degrees centigrade!

You only have to attend a refuelling simulation at the CETIC once to realise that it takes a supervisor’s experienced eye to ensure perfect alignment of the fuel assemblies,” acknowledges Christian Aventurier, project leader for REEL.

In real-life situations, the supervisor has an array of cameras which they coordinate using a video control desk. 3D imaging has been chosen to simulate this system as realistically as possible, making a remarkable entry into the world of energy.

Left real core image, right 3D core image
Left real core image, right 3D core image

Simulate the identification of fuel rod assemblies

One key benefit of the arrival of 3D imaging is that it will make it possible to simulate the individual identification of fuel rod assemblies very accurately. During fuel loading, each new and used assembly must be very clearly identified in order for each to be placed in its designated location, in the right order.

In reality, the number of each fuel assembly is checked at different stages in the process. Our imaging system enables these numbers to be read - even on spent assemblies, on which the figures are harder to read. A supervisor checks that the reference numbers tally,” explains Christian Aventurier.

The desire for realism has resulted in another new feature: the simulators supplied to EDF will activate real PLCs, the same ones used in power plants. This is easier said than done, since it requires contact with the supplier to define a connection protocol.

But at the end of the day, the result will add a greater degree of precision: it will enable theoretical moves calculated by a computer to be distinguished from an actual move performed by a PLC.

Four employees will be working at the same time

The arrival of CORYS simulators is taking place as part of the ten-year overhauls of 1300mW power plants alongside on-site alterations, including the deployment of computerised supervision. This supervision replaces most of the person-to-person information exchanges, and the teams need to familiarise themselves with this new tool both individually and collectively.

The key to successful fuel loading is smooth coordination between the four team members (two operators monitored by two supervisors). For both the traditional and mobile versions of the simulator, all four employees will be working at the same time, under the watchful gaze of their instructor.

One further benefit is that the simulator based at the CETIC will be able to be used for study purposes. Connection to PLCs provides the precision required to reproduce a handling tool movement sequence, understand erratic behaviour, detect a breakdown, and so on. 

 

 Interactive image of instructor station
Interactive image of instructor station 

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STEPS is a blog eager to provide answers and to bring up new issues with simulation users.

Its information is based on 30 years of CORYS experience of simulation and on the feedback from our customers around the world, in the field of Transportation, Power and Hydrocarbons industries.

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