Simulated sources

A recent report by safety experts revealed that staff at a major UK nuclear facility did "not have the level of capability required to respond to nuclear emergencies effectively," a situation that "could have led to delays in responding to a nuclear emergency and a prolonged release of radioactive material off-site." The inspectors found evidence of "significant deficiencies around availability of resources, frequency and quality of training, competency and operational preparedness". The safety exercise had been designed to test the capabilities of the site's fire and rescue team to locate two people after a fictional accident that led to the spillage of radioactive liquid and an aerial release of radioactivity. Despite the fact that the exercise presented 'simple scenarios under ideal conditions,' the service's resources were judged to be 'stretched', according to a report by the UK's Office for Nuclear Regulation.

On the positive side, a spokesman for the site said the successful introduction of an IRMP (Integrated Risk Management Plan) had subsequently led to an improvement notice being closed by the regulator). The IRMP was the first of its kind for the site and has been considered of such value that the ONR has asked for the advice within to be shared with other operators as an example of best practice.

Historically, response training has involved trainees carrying real detection instruments, searching for small 'training sources' and even, in the case of training for nuclear emergencies, responding to hand-written signs showing the level of radiation present at a given location. These methods have, of course, been useful in training responders to deal with nuclear and radiological threats, but compared to the options available today they are severely limited. For example, using real detectors in training temporarily takes equipment out of service and poses the risk of damage and downtime during repair. There are also personal risks to trainees and instructors during exercises that involve the use of hazardous substances, since even small quantities of such materials can pose a real health hazard. The regulatory and financial burden associated with using live sources for training is also significant. A hand-written sign indicating the presence of radiation is of little benefit since it does not allow trainees to develop any understanding of how to handle and use detection instruments or how to interpret the readings they provide.

It is vital that students train with simulators that replicate the appearance and function of the real devices. For example, most dosimeters are rather small and therefore have a small display; in particular the unit of measurement indicator is very small and care is required when reading the display if wearing a respirator or level A suit.

A wide range of simulation systems are now available which can be integrated to stage highly realistic scenarios without the use of real radioactive sources and their associated expense. A major advantage of simulators such as this is that they respond to safe electronic, liquid and powder simulant sources, removing the need to utilise real radioactive sources or materials. As a result, many of the obligatory training requirements in civil nuclear facilities can be carried out at a significantly-enhanced level of safety.

It is possible to conduct individual or group training in a restricted environment by using the dosimeter simulator. A body-mounted local player unit receives an encoded signal representing specific radionuclides from deployed electronic simulation sources, and transmits simulated radiological activity to the simulator. The dosimeter simulator accurately replicates the appearance, function and display of the real dosimeter in a safe and practical manner, providing dosimeter training that matches real-life experience with the real device to provide cost-effective, realistic training for nuclear energy workers.

To maximise capability of the trainees during an incident, any confusion must be tackled during training, not during an incident. Perhaps the greatest value of an exercise using a dosimeter simulator was the ability to generate relatively high instrument readings that most operators had never previously experienced. This in itself exposed the problems that can occur if these readings are either not fully understood or are incorrectly communicated. The realism of the scenario and equipment also means that trainees are fully immersed in the situation; this enables instructors to better evaluate trainee performance, for example, when teams are made up with people who have not worked together before.

To enable safe and efficient training in the use of these devices, it is now possible to use the EPD-Mk2-SIM, a training simulator for the Thermo Scientific™ EPD-Mk2 dosimeter that totally replicates the user interface of the detector. All standard and customer menus and settings are retained; users can copy and use batch files from real EPD-Mk2 dosimeters. Simulated dose history can also be downloaded and analysed using Thermo's Easy EPD™. Likewise, the RDS-200-SIM is a realistic copy of the Mirion RDS200, a Gamma Survey meter. In addition to the RDS-200-SIM, UK nuclear facility operator Magnox also uses the RADSIM GMP-11-SIM, a contamination training simulation probe that connects to either the real Mirion RDS200 or the Argon RDS-200-SIM, and the EPD-Mk2-SIM, a training simulator for the Thermo Scientific™ EPD-Mk2 dosimeter. ¦