Remote Intervention In The Nuclear Environment

The nuclear industry practices remote handling as a standard procedure Here I shall focus on remote intervention, that is to say, operations carried out by powered manipulators and vehicles, as ROV's in underwater environment

At face value it would appear that there is no remarkable difference between remote intervention underwater or in the nuclear environment In both cases we have an environment where access by man is hazardous, difficult, or even impossible and in which manipulative operations need to be achieved Furthermore, there is a strong probability that a machine used in the nuclear environment will also be immersed while performing its task

The question is, are there differences in manufacturing and operating a robot for the nuclear industry or, could any underwater ROV be readily used in the nuclear environment' The answer I am afraid is yes and no

From design stage a vehicle or manipulator truly conceived for nuclear intervention needs to incorporate additional features that are not required underwater That is not to say that ROV's cannot operate in nuclear ponds They may perform for a while but sooner or later they will fail When reliability is demanded from remote intervention tools in the nuclear industry, the following factors must be taken into account

• Hard Ionising Radiations

• Material and Component Resistance to Irradiation

• Other Environmental Criteria

• Decontamination

• Operation and Maintenance Procedures

The principal feature of the nuclear environment is the emission of hard ionising radiations Although very destructive, such radiations are unfortunately imperceptible to man, they are invisible and do not generate any immediate physical or physiological sensation that would make us aware of their presence In the same way that when an xray is taken we feel nothing of the x-rays passing through our body

However, it is not because we do not "feel" these radiations that they do not have an effect upon us, or any other material they permeate Awareness of these insidious radiations must be permanently kept in mind and constant monitoring is a standard working practice in the nuclear industry How much easier it would be if either by say intense light or heat we could perceive them, we would then be more conscious of their danger

It is not my aim to detail the variety of radiations that may be encountered nor to confuse you with the gamut of terms and units that describe them For the purpose of this paper I will only use the following

• the "rad/h" a unit of Irradiation or Dose Rate (the speed at which radiation are emitted or accumulated), and/

• the "rad" a unit of Absorbed Dose (the quantity of radiation accumulated),

even if doing so is not strictly speaking scientifically correct