An open radioactive source is a source of ionising radiation in the form of radioactive material which is not encapsulated or otherwise contained. In the University open sources are mainly used in laboratory- based biological, chemical and medical research, most commonly as a radioisotope in solution but sometimes in solid (e.g. radiochemical powder) or gaseous form. By implication the open nature of the source means that if adequate controls are not in place there is a risk of escape of radioactive material leading to environmental contamination and the potential for exposure of people to ionising radiation, by external and internal routes.
Consequently there are strict regulations governing the use and security of open sources of radioactivity in the workplace. Anyone wanting to acquire and use open sources must follow the instructions below.
The instructions represent best practice in restricting exposure to ionising radiations (as low as reasonably practicable, ALARP) and are in accordance with ‘best available technique’ (BAT) to prevent contamination of the environment with radioactivity.
The instructions apply to all the University campuses and to all Departments of the University.
1. Justification of use of open sources.
Ionising radiation from open sources must only be used if there is no safer alternative way of carrying out the work and use of ionising radiation is unavoidable i.e. use of open sources must be justified.
2. Environmental Permit.
Environmental Permits issued by the Environment Agency are the means by which the keeping, use, accumulation and ultimate disposal of radioactive substances are regulated. Separate Environmental Permits exist for the University main campus and Clinical Sciences Research Laboratories at the Walsgrave campus. There is also a Permit for School of Life Sciences to keep, use and dispose radioactive substances at the Wellesbourne campus.
For new work a check must be made that radionuclides and amounts (i.e. activity levels) intended to be worked with are covered by existing Environmental Permits. If they are not covered a variation to the Environmental Permit must be applied for; new radionuclides must not be acquired before a variation is granted.
The University Radiation Protection Officer is responsible for submitting applications for Permit variations. There are charges for Permit variations and it takes approximately 3 months from application for a Permit variation to be granted.
A copy of the Environmental Permit must be physically posted (displayed) on the premises.
3. Risk Assessment.
A risk assessment must be carried out to identify measures necessary to restrict the exposure of employees and others to ionising radiation from open sources. The work must not begin until the risk assessment has been undertaken.
The risk assessment must consider :
• Exposure potential – e.g. physical nature of the radioactive material, quantity to be used, properties of the radionuclide, frequency of operation, work procedures related to storage, dispensing and handling.
• Exposure protection measures e.g. safety features and maintenance requirements of containment equipment, shielding, designation of areas, radiation monitoring regimes.
• Risks associated with waste handling.
• Plans for controlling exposure in the event of reasonably foreseeable accidents.
• Staff training needs.
Risk assessment must identify reasonably foreseeable ‘emergency’ scenarios for work with open radioactive sources such as loss of containment (spillage or release) of radioactive material or overexposure from ionising radiation. Actions to be taken following an accident or incident must be planned, recorded in writing and included in the area Local Rules.
4. Area designation.
The risk assessment (Instruction 3) must identify whether radioactive material should be used in a Supervised or Controlled Area, based on dose limits.
A Supervised Area must be designated if:
• The annual radiation dose to an employee (aged 18 or over) working in the area might exceed 1mSv.
• It is necessary to keep conditions in the area under review in case re-designation as a Controlled Area is required.
A Controlled Area must be designated if:
• The annual radiation dose to an employee (aged 18 or over) working in the area might exceed 6mSv, i.e. 7.5µSv.h-1 when averaged over the working day,
• The risk assessment indicates that “special procedures “ must be followed to restrict exposure during normal operations or limit the probability of an accident.
• Where access to anyone not connected with the work must be restricted.
Warning signs must be displayed at the entrances to designated areas.
5. Local Rules.
Written instructions in the form of Local Rules must be produced for any Controlled Area or Supervised Area.
Local Rules must give clear and concise instruction on carrying out work with radioactive material in ways that protect against the risk of radiation exposure, and give instructions on what to do in the event of an accident (a contingency plan). They must also include the name of the Radiation Protection Supervisor for the Area, a description of the Controlled or Supervised area, reference to relevant risk assessments and instruction on what monitoring must be carried out.
Local Rules must be on display in the area in which the radioactive material is located.
6. Area Monitoring.
Monitoring must be carried out to confirm that exposure control measures are effective i.e. dose rates do not exceed permissible limits. Records must be kept of the results, and if corrective action is necessary, details of any work carried out and subsequent confirmatory test results must be recorded. The frequency of these tests must be decided by the radiation risk assessment.
Surface contamination monitoring must also be carried out at intervals decided by risk assessment. Monitoring records must be made and kept a minimum of 2 years for reference.
7. Radiation Protection Supervisor.
There must be a Radiation Protection Supervisor appointed for the area in which the radioactive material is located.
8. Source Accountancy.
Any open source radioactive material brought onto University premises must be logged onto a source accounting system at the earliest possible opportunity in order to meet requirements set out in Environmental Permits, to enable the whereabouts of radioactive material to be known at all times and for any loss to be quickly detected.
The minimum information required is:
• Date of receipt on the premises.
• A means of identification (reference).
• The source activity (Becquerels) at time of receipt.
• The source whereabouts e.g. storage location on the premises.
• Records of dilution/usage.
• Disposal details (see Instruction 9).
To meet these requirements the University uses a computer-based source accounting system called IsoStock. Users of open sources must understand how IsoStock is used in the area in which they carry out their work; guidance and instruction must be provided by the local Radiation Protection Supervisor.
Radiochemical inventories must be audited regularly (at least monthly). Records held on IsoStock must be checked to confirm they accurately reflect actual stock levels and storage locations, and vice versa.
Any missing sources must immediately be notified to the University Radiation Protection Officer or Radiation Protection Adviser who will notify, if necessary and as soon as reasonably possible, the Environment Agency, Police and possibly the Health and Safety Executive.
Source Accountancy records must be kept indefinitely or until notified otherwise.
Anyone who creates radioactive waste must receive information and instruction from a Radiation Protection Supervisor about local methods of handling waste safely and compliance with disposal regulations.
Disposal of radioactivity must meet specified conditions;
• Waste must be of physical form and disposed of by routes as specified in an Environment Permit, for example solid waste off-site disposal, liquid disposal to drain, organic solvent liquid waste, gaseous discharge to atmosphere, Very Low Level Waste (VLLW).
• Disposal must be within monthly and annual activity limits for different radionuclides, as specified in an Environment Permit.
• Waste must only be allowed to accumulate on University premises within limits specified in an Environment Permit; the limits are set for quantity of radioactive waste and period of time permissible for accumulation.
A record must be kept of disposal of radioactive material using IsoStock source accounting system.
Users of radioactive material must understand how IsoStock disposal records are managed. Guidance and instruction must be provided by the local Radiation Protection Supervisor.
Where Environmental Permit waste authorisations are shared between Departments there must be collaboration at intervals to review disposal records and demonstrate compliance with the authorised limits.
Annual disposal records must be available to the University Radiation Protection Officer in January each year, who will collate and submit to the Environment Agency on behalf of the Departments.
10. Storage of open sources.
Radioactive open sources must be kept in suitable containers in stores reserved for the purpose, except when in actual use.
Containers must prevent dispersal of radioactive material, they must be suitable for purpose having regard to shielding and they must be labelled with the sample reference, the word ‘radioactive’ and the radiation warning symbol.
An open source store must provide fire resistance, ventilation and suitable shielding.
The store must be lockable for sample security and it must be kept locked unless it can be demonstrated that there is sufficient control to prevent unauthorised access to it when it is unlocked.
The store must bear a label with the radiation warning symbol clearly visible.
If the store is a laboratory fridge/freezer it should be dedicated for use as a radioactive sample store or a shelf within it should be reserved for radiochemical storage and identified as such.
Solvents must not be stored with radioactive materials.
11. Classified Persons.
Anyone carrying out work with radioactive material where there is a risk of annual whole body dose of more than 6mSv per annum or a finger dose more than 150mSv, must be registered as a Classified Person.
The need to register Classified Persons will be identified by the Risk Assessment (Instruction 4).
Classified Persons must have a medical carried out by a Health and Safety Executive appointed doctor. Medicals must be arranged through the University Health, Safety and Occupational Health Service.
12. Personal Dosimetry.
Personal radiation exposure monitoring (dosimetry) must be provided if the risk assessment (Instruction 4) indicates that it is necessary. There are two types of dosimetry badge; film badges for measuring whole body radiation, changed at 2 monthly intervals and thermoluminescent devices (TLD) finger badges for measuring doses to the hand, changed monthly.
If risk assessment indicates that personal dosimetry is necessary the local Radiation Protection Supervisor must be contacted, who will advise on the local administrative arrangements for obtaining and returning dosimetry badges.
Anyone issued with badges must use them as instructed and must return the badges for dose analysis at stipulated times.
13. Radiation workers
Only authorised staff and students are allowed to work with radioactive materials.
Staff and students must receive training before starting work with radioactive substances. They must understand the hazards from ionising radiation and must be knowledgeable about and competent to use control measures to minimise risk. They must also be trained to understand the importance of security and source accountancy arrangements.
Staff and students must be authorised by the RPS for the area, based on them having received training.
A risk assessment must identify what level of training and competence is needed for staff working with radioactive materials.
14. Monitor testing.
Monitoring instruments used to check exposure control measures e.g. dose-rate meters and area contamination monitors, must be tested regularly and calibrated annually. Currently this takes place during November. An email will be sent to RPS's giving at least 2 weeks notice of the calibration.
The University Radiation Protection Officer must be provided with information about monitoring instruments. This must be done so that an up-to-date inventory can be kept by the Health and Safety Department for auditing purposes.
15. Movement and transport of open sources.
For radioactive material intending to be moved (transported) between different sites on public roads a check must be made to see whether special conditions apply, for example type of package and warning labels. The University Radiation Protection Officer must be consulted for advice. Approved couriers must be used. Transport must not be carried out using private vehicles other than in exceptional circumstances for which special arrangements have been made including vehicle insurance cover.
Double containment is a minimum requirement for movement of radioactive samples together with sufficient absorbent material to mop up spillages, should the containment be broken. For some radionuclides, inner and outer containers also act as radiation shielding. Any transport must comply with the Carriage of Dangerous Goods Regulations 2009 (“CDG2009”).
16. Contingency measures.
If it becomes known or it is suspected that there has been an unwanted loss of containment of radioactive material e.g. a spillage, splash or other form of contamination, measures must be taken to prevent any further escape and limit further spread of contamination. Local Rules should be consulted which describe actions and measures to be taken.
An incident report must be made using the University’s intranet-based Accident and Incident reporting system. For major loss of containment the University Radiation Protection Officer must be informed and the Director of Health and Safety.
If it becomes known or it is suspected that a source has been lost or stolen all reasonable steps must immediately be taken to recover it. The University Radiation Protection Officer must be informed immediately.
If it becomes known or is suspected that a person is overexposed to radiation the person’s line manager, the University RPO and the RPA must be informed.