Educational revolution

One area of attention at EDF Energy's new Cannington Court campus in Somerset, UK is nuclear fundamentals training for operators and engineers. Though this training has been provided for many years, it has not yet been effective in embedding the material into the students.

In 2013, INPO Event Report IER l1-11-3 ("Weaknesses in Operator Fundamentals") said that significant events highlight weaknesses in the knowledge, skills, behaviours and practices essential for operators to operate plant safely and effectively - operator fundamentals. In some cases, individuals caused events. In other instances, individuals did not mitigate the effects of power transients. Events included reactor trips, loss of reactor coolant system inventory, unplanned reactivity additions and damage to plant equipment.

In the past, industry efforts to improve operator fundamentals have reduced the number of significant events and reactor trips caused or complicated by weaknesses in operator performance. However, this was a short term effect because the lessons were not well incorporated into operational standards, training and management systems. Events caused by poor operator fundamentals continue to occur too frequently.

One of the problems in the nuclear field is that putting students on a full scope simulator overwhelms them and they find it difficult to concentrate on the task. The Campus recognised that the training of fundamentals must include hands-on experience and simulation to provide the necessary fundamentals knowledge and to embed it in the operator. This can be achieved using either physical models or computer-based systems.

“We're convinced that theory learning is not enough: trainees need practice," says Mike Hogben, learning and technology manager at Cannington Court. "But if they were to start directly on a full-scale simulator, they would be overwhelmed by its complexity. Instead, we've opted for PC-based simulation with modules geared to specific learning needs."

EDF Energy has selected Corys' Nuclear Initial training tool suite. Corys, which is jointly owned by Areva (66%) and EDF, manufactures simulators for the power and transport industries.

Basic principles training

The C-PWR 1300 software covers the basic physical principles and standard operation of a PWR. It is used for courses such as Engie's (previously GDF Suez) Nuclear Trainee Programme, which teaches 80 new recruits - engineers and managers - each year. It is also used by most French universities delivering nuclear degrees, Barcelona UPC, eight Chinese universities, and at Corys for both internal and external courses.

On a typical five-day course, the first three half-days are devoted to conventional exploration of how a PWR works: PowerPoint presentation of the components, drawings describing interactions, and pen and paper for exercises and summaries.

C-PWR takes the stage on the afternoon of the second day. Trainees work either individually or in pairs on a PC. The software gives them a simplified, but highly accurate, dynamic display of the entire unit. They can take the controls, perform actions and observe.
Gradually, trainees are introduced to the complexities of operation. Initially, the software is configured so that just two parameters interact, such as pressure and primary circuit temperature. The first thing they find out is that these temperature-pressure interactions vary greatly in terms of intensity and speed. The trainees are no longer merely learning abstract notions, but visualising, testing, and exploring the physics of the reactor in real time.

After that, other phenomena are introduced. For example, the trainees may start a reaction as part of an exercise dealing solely with the primary circuit. The scope is then broadened to include the secondary circuit, and the temperature-pressure interactions in both circuits begin to have an impact on the electrical power generated. Things start getting complicated and happen faster - and it's not long before the trainees begin to be thrown by some counter-intuitive phenomena.

Experiment first, procedures later

There comes a point at which wholly manual multi-parameter control becomes too much for trainees, and they can no longer monitor everything. At this point, the trainer must allow the trainees to experiment and observe for themselves.

“We let [trainees] experiment and learn by trial and error. They can follow their own path, launch an inappropriate operation, retrace their steps, start another procedure, etc. Only later do we deal with actual procedures," explains Hogben.

Once an exercise has been completed, the trainer recaps, reminding trainees of some basic theory if necessary. Then the exercise is played back for the group as a whole, enabling them to discuss its contents. This allows them to check they have understood properly, and develops team spirit.

EDF Energy is planning to use the C-PWR software during its foundation course, which will last five weeks - rather than eight weeks when it was PowerPoint-based. During the period trainees (in groups of 12, each with their own PC) will have daily sessions using the C-PWR software, along with classroom sessions, group work and tutorials. At the end of the course EDF will evaluate the trainees with 50 multiple-choice questions - the same ones given to US operators after an eight-week course using PowerPoints. Hogben says this will be a good way of seeing whether it has made the right decision on the new learning methods.

Attention levels in past courses have been striking, as learning is lively, stimulating and effective. Multiple-choice tests reveal excellent memorisation. Trainees report that this session on C-PWR 1300 is the most hands-on part of the course, and the most useful in their jobs.

In-depth study of systems and functions

The purpose of M-PWR 1300 is to allow trainees to control one of the unit systems, or a specific function such as electrical distribution, regulation, the xenon effect, and so on. There are 17 modules with alternatives for various reactor series. This training is directed at maintenance technicians, automation engineers and operators.

Once again, the strength of the solution resides in being able to activate part of the reactor, with a restricted focus but an extremely high level of detail, fully in line with actual physical data.

Trainees can see for themselves that if they decide to reduce the pressuriser setpoint, the water temperature in the primary circuit changes. If they choose to reduce electrical power, the entire system reacts and safety mechanisms are activated. Everything is tangible and they can experiment.

Another possibility with a huge educational potential is being able to see how instrumentation and control (I&C) works at the scale of a simple operation.

Trainees often see I&C as a black box: you put a value in at one end to achieve an output at the other, without knowing what happens between. M-PWR 1300 allows the sequence of actions to be revealed, and helps explain why it produces the result it does. This is one of the reasons why Corys is sometimes called upon to train academics taking their first steps in nuclear I&C.

M-PWR simulation modules can be used on PCs for individual work, with data projection in groups or over an intranet for distance learning. One use of the latter is for, training technicians hired to supervise work at nuclear plants. Previously, this type of training took two weeks, one of which was devoted to reminders and refresher teaching. Now, this preparatory phase takes place using an online version of M-PWR, with only one week of classroom training.

Anomalies, incidents and accidents

X-PWR 1300 has been available since 2014. Five US accident experts used it during a workshop devoted to technical discussions. On that occasion, Corys reconstructed the Three Mile Island accident, including the failures recorded, the inaccurate sensor readings, the operators' difficulties in interpreting the data available in the control room, and so on.

The participants tested the scenario and confirmed both its realism and its educational value. They were able to replay it with adjustments; for instance, checking that the primary circuit was properly filled: it seems likely that at the time, this would have prevented the partial core meltdown.

Operators, safety engineers, and crisis teams can all use X-PWR 1300 to practice and maintain their reflexes in the face of extremely rare circumstances in which approximation is not an option. Accident scenario initiating events available on X-PWR include: Small Break LOCA, LargeBreak LOCA, SG Tube Rupture, Faulted Steam Generator, Loss of Feedwater/Heatsink and Main Steam Line Break. While full scope simulation remains vital to achieve the immersive effect, PC-based software has the advantage of being accessible at any time - and regular training ensures appropriate actions at times of crisis.