The treatment unit

 

An accelerated electron treatment unit is characterised by its small size. Two types of installation may be considered:
  • An installation which is integrated into the production line for ‘on line’ treatment of products. This is often the case for industrial applications or for those used for environmental purposes.
  • Tailor made installations, for medical applications or specialist applications within the farm produce industry.
Description of a typical treatment unit

1. General set-up

  • A concrete cell on two levels, containing the accelerator and the conveying equipment.
  • Technical suite: control room and dosimetric control area as well as electrical installations.

The ground area needed is about14 x 18 m (250 m2), the height is of the order of 7.70 m.

2. The equipment

The treatment unit is a mini-factory, equipped to function completely independently:

  • The accelerator, inside which electrons are subjected to a series of successive accelerations until the required level is achieved..
  • The product conveyors – supplying, passing through, evacuating.
  • The technical and security suite.
  • The dosimetric equipment and production management equipment, used to qualify, validate, control and administer the treatments.
  • The micro-processor which controls the running of the installation

Products may be treated loose or pre-packaged. The treatment rate for a unit is proportional to its power and inversely proportional to the treatment dose.

For industrial applications it is necessary to retain a rate of 200 kg/hour, for1 kW and 10 kGy. For sterilisation, a rate of 0.5 m3/hour, for 1 kW and 25 kGy is needed.

   Questions & Answers

Can an installation function continuously, 24 hours out of 24?

  • Certainly, with three teams. Production time may thus attain 6,500 hours per year.

What needs to be controlled during production?

  • The minimum dose of radiation which is controlled as and when the need arises by the dosimetric equipment.

What does the security equipment consist of?

  • Protection against ionising radiation when the system is in use as well as normal safety devices (emergency stop mechanism, fire precautions)

Does the radiation produce a rise in temperature in the treated products?

  • No. At the dose of 25 kGy (that used most frequently) the rise in temperature will not exceed 10°C.