authorization and inspection of cyclotron facilities radiation protection of staff

Authorization and Inspection of Cyclotron Facilities

Radiation Protection of Staff


1. Principles of radiation protection;2. Conditions of employment relevant to radiation

protection (e.g.. working hours and location);3. Classification of areas;4. Optimisation of procedures;5. Local rules and supervision;6. Individual monitoring and exposure assessment;


7. Personal protective equipment8. Radiation safety instructions9. Staff and pregnancy10.Health surveillance11.Dose records12.Dose constraints


Objective

• To understand the importance of an effective safety program to assure the protection of radiation workers;

• To be able to apply the principles of the protection program to a cyclotron facility;

• To appreciate the specific issues related to cyclotrons for occupational exposure.


OCCUPATIONAL EXPOSURE

Within a cyclotron facility:

Very high dose rates are present in the vaults during operation of the accelerator.

• High activities are handled routinely, resulting in a potential risk of high doses to and important contamination of staff.

• Employers are obliged to ensure safe working conditions.• Optimisation of protection is essential.


The type and magnitude of occupational exposure depends on the occupation or profession.

For cyclotron facilities, the risk is partially the result of the exposure received as a normal part of the profession but is mainly related with the potential exposure to very high doses that might result from an accident or incident.


• The professions involved may vary from one facility to another.


Other staff potentially exposed due to cyclotron operation:

Domestic staff, technical staff (e.g. electricians, plumbers)

require training and, potentially, may also require personal

monitoring.


Normal Exposure“An exposure which is expected to be received under normal operating conditions of an installation or a source, including possible minor mishaps that can be kept under control.”For example:

• Neutron and gamma background radiation through the shielding during cyclotron operation;

• Radionuclide background radiation in the hot lab;

• Exposure of a maintenance worker from an activated internal part of the accelerator.


Potential exposures“Exposure that is not expected to be delivered with certainty but that may result from an accident at a source or owing to an event or sequence of events of a probabilistic nature, including equipment failures and operating errors.”

In principle, potential exposures are avoidable and the risk can be minimized by:

• prevention• Education/training

• protective equipment• mitigating the effects


Optimisation

If a radiation exposure is justified it should nevertheless be optimised such that any risks due to radiation exposure are minimised. (ALARA).

• As• Low• As• Reasonably• Achievable


Dose monitoring

In general, staff of cyclotron facilities should however be individually monitored, e.g. using a film badge, TLD or pocket electronic dosimeter.

All readings should be recorded for review by the RPO and Regulatory Body


INTERNAL DOSE MONITORING

During normal operations, routine monitoring of internal contaminations of staff should not be performed. For specific maintenance works and after any incident involving external contamination, whole body counting should be considered.

As for external exposure, readings should be recorded for review by the RPO and Regulatory Body


Contamination monitoring

On every exit from the controlled area, a thorough monitoring of contamination of hands and feet should be performed to guarantee an early detection and to prevent any spread of the contamination.

Special detectors are placed at the exit of the controlled area.

Readings should also be recorded.


Records to be kept

“Employers, registrants and licensees shall maintain exposure records for each worker for whom assessment of occupational exposure is required.”

Dose records are a valuablesource of information for

the Regulatory Body

Records shall include:• Nature of the work;• Time of employment/monitoring;• Doses received including unusual exposure.


• when any of the individual dose limits are exceeded;

Investigation and follow-up is required:

• when indicated by QA activities;

• after equipment failure;

• after any accidental exposure,

Investigation

• when a set action level has been reached;


• as soon as possible after the event. A written report should be prepared showing: the doses received the causes of the event the corrective actions taken

Regulations may require a copy of the report to be submitted to the Regulatory Body without delay.

InvestigationInvestigation and follow-up is required:


• Provide an important opportunity to learn (and promote the facility’s safety culture).

Investigations and reports

• The aim should not be to lay blame.• Publication of the incident / accident will help others to avoid

similar problems.• It may be useful to include an external expert in the

investigation.• Documentation is essential, particularly where there is a risk of

litigation.

Investigation


Follow-up

• Medical follow-up of exposed individuals may be required.

• Check that the corrective measures actually work.• Include the corrective measures in ongoing employee

education.


Pregnant workers

A prescribed dose constraint should be readily achievable provided licensees maintain appropriate protection standards and both staff and management have a sound safety culture. The contamination risk should be considered

Notification of pregnancy should not be a reason to exclude a female worker from her normal duties.

Occupationally exposed female staff should notify the RPO / licensee of pregnancy as soon as possible.


• No person under the age of 16 years shall be subjected to occupational exposure.

Age limitations

• No person under the age of 18 years shall be allowed to work in a controlled area unless supervised, and only for the purpose of training.


Workers Undertaking an Intervention

No worker undertaking an intervention shall be exposed in excess of the maximum single year dose limit for occupational exposure, except: for the purpose of saving life or preventing serious

injury;

if undertaking actions to prevent the development of catastrophic conditions.”

if undertaking actions intended to avert a large collective dose; or

authorization and inspection of cyclotron facilities radiation protection of staff

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