Occupational exposure arising from the use of radiation

THE FACILITY AND THE CONTRACTOR

In some situations, an itinerant worker will need to take a source of ionizing radiation into an area of a facility in which they may also be exposed to ionizing radiation arising from the normal operation of the facility. Examples include industrial radiography performed by itinerant workers at a facility for processing raw materials containing elevated levels of naturally occurring radioactive material, non-destructive testing in a nuclear power plant, or the exchanging of a radioactive source at an irradiation facility.

In general, the guidance given in Sections 3.1–3.3 remains relevant.

Additional matters that need to be noted are covered in the following paragraphs.

3.4.1. Access to controlled areas

The itinerant worker may need to undertake work in areas in which there is either a significant ambient dose rate arising from the normal operation of the facility or the potential for relatively high dose rates if malfunctions of certain equipment or failures to follow safety procedures were to occur. The choice of an appropriate dose rate at which to erect barriers and signs needs to be discussed and agreed between the contractor and the management of the facility before work commences, consistent with applicable State regulations or regulatory guidance. Consideration may also need to be given to the timing of the proposed work, if changes in scheduling may reduce the magnitude of the radiation field(s) or the number(s) of workers in the work area(s), or modify other factors affecting radiation doses projected to be received.

3.4.2. Local rules and procedures

Work will have to be carried out not only in accordance with the contractor’s local rules and procedures but also in accordance with the local rules and procedures for those sources associated with the facility. The contractor may, therefore, need to modify its planned local rules and procedures to incorporate certain aspects of the local rules and procedures of the facility.

The contractor’s local rules and procedures and those of facility management are to be written in such a mutually agreed way, so as to ensure that there are no conflicting requirements.

Most often, an RWP is developed to document protection and safety precautions to be implemented. The RWP is, generally, issued by the facility’s RPO or radiation protection staff, but may be issued by a work planning organization in collaboration with the RPO or radiation protection staff.

Applicable to the situation described in Section 3.4, the RWP would reflect the input of the itinerant workers, their employer and the permanent staff of the facility, both in identifying protection and safety measures and also in developing implementation plans to avoid conflicting requirements and to ensure that doses are controlled in accordance with the requirements for optimization of protection and safety. The RWP may include the following, where applicable, to the planned work [2]:

(a) Dose rate maps of the working area, produced from a radiation survey made prior to the work or otherwise estimated; estimates of dose rates in the working area expected during the primary work steps; and locations expected to remain low dose rate areas as the work progresses.

(b) Estimates of contamination levels in the working area, produced from a radiation survey made prior to the work or otherwise estimated; and estimates of contamination levels expected during the primary work steps.

(c) Delineation of any additional radiation monitoring to be carried out before or during the work.

(d) Estimates of individual and collective dose for the work, often for each primary work step.

(e) Delineation of any additional dosimetry to be worn by the workers during the work or during specified work steps.

(f) Delineation of protective equipment to be used during the work or during specified work steps.

(g) Details of time or dose restrictions; and values of preselected levels (e.g. of dose rate, dose or contamination) requiring investigation if exceeded.

(h) Instructions on when to contact the RPO and/or guidance on immediate actions to take if specified stop work criteria are met, preselected investigation levels are exceeded or when there is otherwise believed to be jeopardy of loss of control of the work as planned.

The local rules and procedures are likely to include the use of a pre-job briefing or similar communications forum, whereby the itinerant and other workers can provide input to enhance the assessment of the work plans and also ask questions to promote an understanding of the risks of the planned work and the means being implemented to eliminate, mitigate and/or balance those risks.

In the situation where the itinerant workers are from a different State from that of the facility management, consideration may need to be given to the provision of the local rules and procedures verbally and/or in writing in a language understood by the itinerant workers. Such communications relate to the GSR Part 3 requirement that workers “understand their responsibilities and can perform their duties competently, with appropriate judgement and in accordance with procedures” (para. 2.44 of GSR Part 3 [1]).

3.4.3. Training

Special training for the itinerant workers may be required because of the potential for exposure due to sources under the control of the facility, even though the itinerant workers may already be trained in connection with their own use of radiation. Many facility managers, for example, require contract radiographers and their RPOs to be trained to a facility specified level.

3.4.4. Radiological instrumentation installed at the facility

Consideration is to be given to the possible impacts of the contractor’s radiation source on any instrumentation that is affected by radiation and is installed at the facility. For example, the impact is to be addressed of the contractor’s source on some smoke detection systems, area gamma monitors and criticality incident detection systems, and the risk of unnecessary false alarms.

In the event that the reasonable possibility of such an incident is identified, appropriate corrective actions are to be taken. These could include the use of smaller sources or collimated radiation beams to minimize or localize exposure rates, or the deactivation of some instrumentation for a limited period.

The possibility may also exist for the radiation fields at the facility to affect the choice of radiation detection instrumentation used by the itinerant workers in performing their tasks. Alternatively, means to adjust for facility related exposure rates or energy spectrums may be needed.