SSG-58 Radiation Safety in the Use of Nuclear Gauges

Transmission gauges, used to measure density, thickness and levels of materials: The source housing and the radiation detector are on opposite sides of the material under investigation and the radiation is attenuated as it travels through the material. Such gauges traditionally used radioactive sources (beta and gamma); however, X ray generators are increasingly being used and are now a popular type of radiation source in transmission gauges.

Backscatter gauges, used to measure the thickness of coatings: The detector and source housing are on the same side of the material and therefore the detector has to be shielded from the primary radiation. The radiation enters the material, interacts with it and scatters back. Radioactive sources (beta, gamma and occasionally neutron) are typically used in such gauges. The back-scattered radiation is measured by the radiation detector and is related to the coating thickness.

Reactive gauges, for example used for elemental analysis: Certain radiation sources (X ray and neutron) can cause fluorescent X ray emissions in the material being analysed. X ray generators and neutron sources (radioactive sources or radiation generators) are used in some reactive gauges.

Provides the statutory basis for requirements for protection and safety for all exposure situations;

Specifies that the prime responsibility for protection and safety rests with the person or organization responsible for facilities and activities that give rise to radiation risks;

Specifies the scope of its applicability;

Establishes and provides for maintaining an independent regulatory body with clearly specified functions and responsibilities for the regulation of protection and safety;

Provides for coordination between authorities with responsibilities relevant to protection and safety for all exposure situations.”

Notification and authorization;

Review and assessment of facilities and activities;

Inspection of facilities and activities;

Enforcement of regulatory requirements;

The regulatory functions relevant to emergency exposure situations and existing exposure situations;

Provision of information to, and consultation with, parties affected by its decisions and, as appropriate, the public and other interested parties.”

Registers of sealed sources and radiation generators;

Records of doses from occupational exposure;

Records relating to the safety of facilities and activities;

Records that might be necessary for the shutdown and decommissioning or closure of facilities;

Records of events, including non-routine releases of radioactive material to the environment;

Inventories of radioactive waste...”

The transport of radioactive sources;

The location of radioactive sources;

Incidents involving radiation sources, such as loss of radioactive sources, damage to radioactive sources and theft of radioactive sources or radiation generators.

Review of compliance with the conditions of the authorization to possess and use nuclear gauges; for example, checking that the inventory includes only those gauges and radiation sources that are authorized, and that gauges are used only for authorized purposes at authorized locations. The temporary use of gauges at client facilities should be subject to specific authorization conditions relating to temporary storage, operation and transport of the gauges. If any authorized source is missing or if any source is found to be not properly authorized, the matter should be investigated and appropriate actions implemented (an immediate search should be performed for missing sources, and any unauthorized sources should be brought under regulatory control).

Confirmation that radiation sources and nuclear gauges meet the acceptance criteria and performance criteria established by the regulatory body.

Measurement of radiation levels around nuclear gauges and confirmation of compliance with authorized levels.

Review of the records of workplace monitoring and of safety assessments performed by the operating organization, to determine whether (and under what circumstances) personal dosimetry is appropriate.

Observing the use of nuclear gauges, including procedures for safe use and, where appropriate, source handling procedures.

Checking the arrangements for the safety and security of each radiation source before the installation of the gauge, during its use and after the end of the useful life of the source.

Review of control measures (e.g. the conduct of periodic source inventory checks, controls to ensure that sources are only used by authorized individuals, use of appropriate engineered controls), storage conditions for portable gauges and for disused sources, and emergency procedures.

Review of compliance with regulatory requirements for transport of radioactive material (see Section 12), especially with regard to the use of portable gauges at client facilities.

Where appropriate, performance of on-site inspections at client facilities where portable gauges are being used.

Shall adopt objectives for protection and safety in accordance with the requirements of [GSR Part 3];

Shall apply measures for protection and safety that are commensurate with the radiation risks associated with the exposure situation and that are adequate to ensure compliance with the requirements of [GSR Part 3].”

The measures and resources that are necessary for achieving the objectives for protection and safety have been determined and are duly provided;

The programme is periodically reviewed to assess its effectiveness and its continued fitness for purpose;

Any failures or shortcomings in protection and safety are identified and corrected, and steps are taken to prevent their recurrence;

Arrangements are made to consult with interested parties;

Appropriate records are maintained.”

Applying the requirements for protection and safety coherently with other requirements, including requirements for operational performance, and coherently with guidelines for security;

Describing the planned and systematic actions necessary to provide adequate confidence that the requirements for protection and safety are fulfilled;

Ensuring that protection and safety are not compromised by other requirements;

Providing for the regular assessment of performance for protection and safety, and the application of lessons learned from experience;

Promoting safety culture.”

Promoting individual and collective commitment to protection and safety at all levels of the organization, including staff responsible for administration, security and storage facilities, as well as workers involved in the operation and maintenance of nuclear gauges.

Ensuring a common understanding of the key aspects of safety culture within the organization.

Supporting individuals and teams in performing their tasks safely and successfully, with account taken of the interactions between individuals, the nuclear gauge technology and the organization. For example, if maintenance work is to be performed in the vicinity of a gauge installation, coordination among the maintenance staff, gauge operating staff and the radiation protection officer is necessary.

Encouraging open communication and participation of gauge operating staff, the radiation protection officer(s) and other workers in the facility in the development and implementation of policies and procedures dealing with protection and safety relating to nuclear gauges.

Ensuring accountability of the organization and of individuals at all levels for protection and safety in the procurement, storage, installation, operation, maintenance, handling and safe management of sources until their safe disposal after the end of their useful life.

Encouraging a questioning and learning attitude, discouraging complacency, with regard to protection and safety and providing means by which the organization continually seeks to develop and strengthen its safety culture.

Sound ergonomic principles are followed in the design of equipment and the development of operating procedures, so as to facilitate the safe operation and use of equipment, to minimize the possibility that operator errors could lead to accidents, and to reduce the possibility that indications of normal conditions and abnormal conditions could be misinterpreted.

Appropriate equipment, safety systems and procedural requirements are provided, and other necessary provision is made:

To reduce, as far as practicable, the possibility that human errors or inadvertent actions could give rise to accidents or to other incidents leading to the exposure of any person;

To provide means for detecting human errors and for correcting them or compensating for them;

To facilitate protective actions and corrective actions in the event of failures of safety systems or failures of measures for protection and safety.”

Shall follow any applicable rules and procedures for protection and safety as specified by the employer, registrant or licensee;

Shall use properly the monitoring equipment and personal protective equipment provided;

Shall cooperate with the employer, registrant or licensee with regard to protection and safety, and programmes for workers’ health surveillance and programmes for dose assessment;

Shall provide to the employer, registrant or licensee such information on their past and present work that is relevant for ensuring effective and comprehensive protection and safety for themselves and others;

Shall abstain from any wilful action that could put themselves or others in situations that would not be in accordance with the requirements of [GSR Part 3];

Shall accept such information, instruction and training in protection and safety as will enable them to conduct their work in accordance with the requirements of [GSR Part 3].”

The development and use of specific restrictions on exposure and other means of ensuring that the measures for protection and safety for workers who are engaged in work that involves or could involve a source that is not under the control of their employer are at least as good as those for employees of the registrant or licensee;

Specific assessments of the doses received by workers as specified in (a) above;

A clear allocation and documentation of the responsibilities of the employer and those of the registrant or licensee for protection and safety.”

Shall obtain from the employers, including self-employed persons, the previous occupational exposure history of workers … and any other necessary information;

Shall provide appropriate information to the employer, including any available information relevant for compliance with the requirements of [GSR Part 3] that the employer requests;

Shall provide both the worker and the employer with the relevant exposure records.”

The provision of individual dosimetry and dose record keeping, if required (see Section 6);

Health surveillance arrangements, if required (see Section 4);

Workplace monitoring arrangements (see Section 7);

Local rules (see Section 4).

The dose rates from shielded and unshielded radioactive sources and from radiation generators (X ray and neutron), as appropriate;

The exposure of workers and the public from normal operation of nuclear gauges, and potential exposures from reasonably foreseeable incidents (including exposures due to loss or reduction of radiation shielding incorporated in the design of the nuclear gauge, due to contamination from a damaged radioactive source, and from other scenarios, including very low probability events);

Limits and technical conditions for operation of the nuclear gauge(s);

Ways in which structures, systems and components, as well as procedures relating to protection and safety, might fail or might otherwise lead to potential exposures, and the consequences of such failures or potential exposures;

Ways in which external factors, operating errors and human factors could affect protection and safety;

The implications of any proposed modifications for protection and safety;

Any uncertainties or assumptions, and their implications for protection and safety.

The engineered control measures that are necessary for safety, for example to prevent access to the primary beam of a nuclear gauge.

The administrative controls that are necessary for safety, for example the procedures required to control entry into vessels on which level gauges are installed, particularly when the shutter is open.

The development of safe working procedures (local rules) for storage, operation, maintenance of a source inventory, servicing and maintenance, and management of disused sources.

Procedures for designating controlled areas and supervised areas (permanent and temporary).

Any measures necessary for the protection of the public.

The assessment of occupational exposures (see Section 6).

The training programme for gauge users and other persons (see Section 5).

An effective emergency preparedness and response programme to manage reasonably foreseeable events (including very low probability events). This should include: information on reasonably foreseeable incidents, the measures necessary to prevent or minimize the likelihood of occurrence of such incidents, and the necessary emergency response arrangements (including emergency plans and procedures, and emergency equipment) (see Section 13).

The security of radioactive sources in fixed gauges and portable gauges, with the objective of deterring, detecting, delaying and responding to the theft of sources (see Section 9).

When safety might be compromised or affected as a result of modifications to facilities or to activities;

When the acquisition of a new radiation source or a source with different characteristics is planned;

When operating experience or the investigation of incidents, failures or errors indicates that current safety measures are invalid or are not fully effective;

When significant changes to relevant standards, regulations or guidance have been made or are envisaged.

Engineered controls;

Administrative controls;

Personal protective equipment.”

Chemical hazards;

Fire and explosion;

Noise and vibration;

Mechanical hazards (e.g. lifting equipment, rollers);

Heat (e.g. furnaces, ovens);

Hazards relating to pressure vessels.

The management structure and policies relevant to protection and safety;

The assignment of individual responsibilities for protection and safety;

A training programme on the nature of the radiation hazards, and on the measures required for protection and safety;

Local rules and the arrangements for supervision of the work with nuclear gauges;

The designation of controlled areas and supervised areas, as appropriate;

Safety and security of radioactive sources including management of disused sources;

Emergency preparedness and response;

The arrangements for assessing occupational exposure (if required) and for monitoring the workplace, including the acquisition, testing and maintenance of workplace monitoring instruments;

The programme for health surveillance of workers (if required);

A system for recording and reporting information relating to the control of exposures, the decisions regarding measures for occupational radiation protection and safety, and the results of individual monitoring and workplace monitoring;

Methods for periodically reviewing and auditing the performance of the radiation protection programme;

Requirements for quality assurance and procedures for process improvement.

Shall establish in writing local rules and procedures that are necessary for protection and safety for workers and other persons;

Shall include in the local rules and procedures any relevant investigation level or authorized level, and the procedures to be followed in the event that any such level is exceeded;

Shall make the local rules and procedures and the measures for protection and safety known to those workers to whom they apply and to other persons who may be affected by them;

Shall ensure that any work in which workers are or could be subject to occupational exposure is adequately supervised and shall take all reasonable steps to ensure that the rules, procedures, and measures for protection and safety are observed;

Shall designate, as appropriate, a radiation protection officer in accordance with criteria established by the regulatory body.”

Regular reviews of the radiation protection programme;

Reviews of occupational radiation doses, workplace monitoring programme results and any incident reports prepared by the radiation protection officer;

Reviews of results of audits on the performance of the radiation protection programme;

Making recommendations to senior management for improvements in the radiation protection programme;

Provision of guidance and direction on the performance of the radiation protection officer’s duties;

Monitoring the investigation of any incident with the potential for unplanned exposure to radiation;

Preparation of reports about relevant radiation safety issues, and dissemination to managers and workers, as appropriate.

Controlling exposures or preventing the spread of contamination in normal operation;

Preventing or limiting the likelihood and magnitude of exposures in anticipated operational occurrences and accident conditions.”

Shall delineate controlled areas by physical means or, where this is not reasonably practicable, by some other suitable means.

Shall, where a source is only intermittently brought into operation or energized, or is moved from place to place, delineate an appropriate controlled area by means that are appropriate under the prevailing circumstances and shall specify exposure times.

Shall display the symbol recommended by the International Organization for Standardization [see Ref. 18] and shall display instructions at access points to and at appropriate locations within controlled areas.

Shall establish measures for protection and safety, including, as appropriate, physical measures to control the spread of contamination and local rules and procedures for controlled areas.

Shall restrict access to controlled areas by means of administrative procedures such as the use of work permits, and by physical barriers, which could include locks or interlocks, the degree of restriction being commensurate with the likelihood and magnitude of exposures.

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Shall periodically review conditions to assess whether there is any need to modify the measures for protection and safety or the boundaries of controlled areas[.]

Shall provide appropriate information, instruction and training for persons working in controlled areas.”

Level 1: Personnel working in a supervised area.

Level 2: Personnel working with radiation sources (e.g. engaged in handling, transport, calibration, assembly and installation of gauges) and/or working in controlled areas.

An effective dose of 20 mSv per year averaged over five consecutive years⁶⁶ (100 mSv in 5 years) and of 50 mSv in any single year;

An equivalent dose to the lens of the eye of 20 mSv per year averaged over five consecutive years (100 mSv in 5 years) and of 50 mSv in any single year;

An equivalent dose to the extremities (hands and feet) or to the skin⁶⁷ of 500 mSv in a year.

An effective dose of 6 mSv in a year;

An equivalent dose to the lens of the eye of 20 mSv in a year;

An equivalent dose to the extremities (hands and feet) or to the skin67 of 150 mSv in a year.

Dosimeters should be worn by relevant personnel at all times when performing work with radiation sources.

Dosimeters should be worn in accordance with the recommendations of the dosimetry service provider.

For passive dosimeters (e.g. thermoluminescent, optically stimulated luminescent and film dosimeters), the measuring element should be correctly positioned in the dosimeter holder.

The dosimeter should be worn only by the person to whom it is issued.

Care should be taken to avoid damaging the measuring element of the dosimeter (dosimeters can be damaged by water, high temperature, high pressure or physical impact).

Dosimeters should not be exposed to radiation when not being worn by the worker (the dosimeter should be stored away from sources of radiation when not in use).

Passive dosimeters should be promptly processed by the dosimetry service at the end of the period of wear. Dosimeters that have been returned early owing to a suspicion of abnormal exposure should be processed urgently.

The dosimetry service should be informed if the operating organization suspects that the dosimeter has been damaged or has been exposed to radiation while the worker to whom it was assigned was not wearing it, in order that the correct dose to be assigned to the worker can be determined.

Neutron dosimeters with a suitable neutron energy response should be worn by personnel who receive occupational exposures from working with nuclear gauges containing neutron sources or neutron generators.

Active personal dosimeters should not be used as a replacement for workplace monitoring instruments (e.g. dose rate meters).

Active personal dosimeters should be tested periodically in accordance with national recommendations and guidance from the manufacturer.

Active personal dosimeters should be calibrated in terms of the radiation fields likely to be encountered in the workplace.

Alarm settings of the active personal dosimeters should reflect an appropriate level of dose and/or dose rate and the alarm level should be visible during operation of the device.

Changes to active personal dosimeters should not be allowed, except by persons with appropriate roles and responsibilities.

Shall provide workers with access to records of their own occupational exposure;

Shall provide the supervisor of the programme for workers’ health surveillance, the regulatory body and the relevant employer with access to workers’ records of occupational exposure;

Shall facilitate the provision of copies of workers’ exposure records to new employers when workers change employment;

Shall make arrangements for the retention of exposure records for former workers by the employer, registrant or licensee, as appropriate;

Shall, in complying with (a)–(d) above, give due care and attention to maintaining the confidentiality of records.”

Around storage facilities for gauges and sources, to ensure that an adequate level of shielding is provided;

Around gauges during routine operations, to confirm that dose rates remain below any values specified in national regulations or guidance and by the operating organization;

Around gauges during maintenance operations, to confirm that the gauge shutter is closed or that the radiation generator is switched off;

At the operators’ positions during use of portable gauges, to confirm that radiation levels are acceptable;

At the operators’ positions during source loading and unloading operations;

At the entrance to a gauge enclosure, to confirm that the gauge shutter is closed or that the radiation generator has ceased to emit radiation;

Around the transport package before transporting a portable gauge to and from the site, to confirm the presence of the source;

Around vehicles transporting portable gauges before departure to and from the site.

The location and description of each radiation generator or radioactive source for which they are responsible;

The activity and form of each radioactive source for which they are responsible.”

Sources in installed gauges should be accounted for at least once per month.

Sources in portable gauges should be accounted for every day they are out of the store and once a week when they are in storage.

Source capsules should be designed, manufactured and tested to ensure that they meet the relevant requirements set out in ISO 2919 [11] or an equivalent national standard.

In the case of gamma and neutron sources, source capsules should be certified as meeting the requirements for special form radioactive material as established in IAEA Safety Standards Series No. SSR-6 (Rev. 1), Regulations for the Safe Transport of Radioactive Material, 2018 Edition [27].

Source capsules should be leak tested in accordance with the requirements set out in ISO 9978 [28] or an equivalent national standard, and there should be a valid leak test certificate that is traceable to each individual source (see also para. 10.31).

Source capsules should be marked in accordance with the requirements of ISO 2919 [11] or an equivalent national standard. At a minimum, sources should be marked with the radiation symbol (trefoil) [18] and the word “RADIOACTIVE”. They should also be durably marked with the manufacturer’s serial number.

The international ionizing radiation symbol (trefoil) [18];

The word “RADIOACTIVE” in letters not less than 10 mm in height, together with a brief warning in a language appropriate to the country or region of use;

The chemical symbol(s) and mass number of the radionuclide(s) for which the device is suitable (e.g. ¹³⁷Cs or ²⁴¹Am);

The activity of the source(s) on a stated date;

The make, model and serial number of the device;

The name of the manufacturer and/or distributor of the source.

The chemical symbol and mass number of the radionuclide(s);

The activity of the source(s) on a stated date;

The identification number of the sealed source(s);

The name of the manufacturer.

Provide adequate shielding.

Be physically secure (e.g. locked when not in use).

Be a dedicated enclosure that is used exclusively for storage of nuclear gauges and associated radioactive sources, and is not used as a general storage area for other goods.

Be fireproof and not contain other hazardous materials (e.g. flammable, explosive, toxic or corrosive substances). Such hazardous material should not be stored near the storage facility for radioactive sources.

Be protected from environmental conditions that might adversely affect the integrity of the gauges.

Be appropriately labelled (e.g. with the radiation symbol [18] and warning notices in the local language).

Radioactive sources (including calibration sources, as applicable) and radiation generators should, subject to approval by the regulatory body, be transferred to an authorized organization for safe disposal. If possible, the operating organization should return the source or generator to the original supplier; alternatively, the operating organization may take another action as authorized by the regulatory body. Comprehensive records should be kept by the operating organization of all authorizations for the storage, transfer or disposal of radioactive sources (including any certificates provided by recipients or by disposal facilities for radioactive waste). The relevant records should be maintained as specified by the regulatory body.

The operating organization should return disused neutron generators to the original supplier. Otherwise, the generator should be made inoperable and, subject to approval by the regulatory body, transferred to an authorized organization for safe disposal (i.e. of the tritium source).

In cases where all radiation sources are to be removed from the facility, all radiation symbols (trefoils) and other relevant notices should be removed from the facility and a workplace monitoring survey (see Section 7) should be conducted by the radiation protection officer or a qualified expert to provide additional confirmation that the radioactive sources have been removed from the site. A final decommissioning plan should be prepared in advance, which includes the final radiation survey and details of the storage, transfer or disposal of sources of radiation. The final decommissioning plan is required to be submitted to the regulatory body for review and approval (see Requirement 11 of IAEA Safety Standards Series No. GSR Part 6, Decommissioning of Facilities [30]). Further recommendations are provided in IAEA Safety Standards Series No. SSG-49, Decommissioning of Medical, Industrial and Research Facilities [31].

The operating organization should inform the relevant authorities when all sources of radiation have been removed from the site.

Radioactive waste should be managed in accordance with recommendations provided in IAEA Safety Standards Series No. SSG-45, Predisposal Management of Radioactive Waste from the Use of Radioactive Material in Medicine, Industry, Agriculture, Research and Education [32] or an equivalent national standard, and in accordance with regulatory requirements.

An option for disposal of sealed sources in nuclear gauges is borehole disposal. Recommendations on borehole disposal facilities are provided in IAEA Safety Standards Series No. SSG-1, Borehole Disposal Facilities for Radioactive Waste [33]. A technical manual on borehole disposal of disused sealed sources is provided in Ref. [34].

From the gauge supplier to the operating organization’s facility;

From the operating organization’s facility to the authorized site of operation in the case of portable gauges;

From the operating organization’s facility to the supplier or other suitably authorized facility at the end of the useful life of the source, if it has become disused for some other reason, or following an accident involving the source.

The consignor (the person or organization that prepares a consignment for transport);

The carrier (the person or organization that undertakes transport of radioactive material);

The consignee (the person or organization that receives a consignment).

The energy resulting from a nuclear chain reaction or from the decay of the products of a chain reaction; or

Radiation exposure” [8].

Jammed or broken shutters;

Other mechanical damage to gauges (e.g. crushing);

Abnormal (i.e. higher than expected) dose rates;

Missing sources;

Leaking sources due to mechanical impact, fire or corrosion;

Malevolent actions such as theft of nuclear gauges (especially portable gauges).

Nuclear gauges and associated equipment should meet current regulatory standards.

Workers:

Should be properly trained and qualified, and they should be competent;

Should follow the local rules and other relevant procedures;

Should use calibrated workplace monitoring instruments and, if appropriate, wear suitable personal dosimeters before, during and after every source use, and in accordance with the radiation protection programme (see Section 4);

Should undertake regular and appropriate inspections of equipment before use;

Should make proper use of emergency equipment.

A clear statement of roles and responsibilities;

A concept of operations;

Communication and coordination arrangements;

Protocols for notification of an emergency;

Instructions to site personnel;

Instructions for delineation of the affected area and access control;

Measures to protect emergency workers.

Appropriate workplace monitoring instruments to measure both high and low dose rates;

Active personal dosimeters;

Barrier materials and warning notices for the temporary designation of a controlled area;

If appropriate, suitable local shielding, such as blanking plates to shield the primary beam in the event of the shutter being stuck in the open position;

Forceps or remote handling tongs, and a spare source container with adequate shielding;

Wipe test kit for leak testing sources and for other surface contamination checks;

Communication equipment (e.g. portable phones);

Spare batteries and torches.

Quickly recognize an abnormal situation that might constitute an emergency and implement the appropriate emergency procedures.

Remain calm and move away from the gauge and ensure that any other workers in the vicinity are evacuated and informed that there might be an emergency.

Inform the radiation protection officer of the operating organization.

Measure the dose rates and record any doses measured by active personal dosimeters, if these have been worn.

Confirm, establish or re-establish controlled area barriers on the basis of dose rate reference levels consistent with regulatory requirements and the emergency plan and procedures.

Prevent access to the controlled area.

Use necessary personal protective equipment.

Maintain surveillance of the controlled area.

Inform the relevant authorities (and the client, if the emergency occurs at the client’s site) and seek assistance as prescribed in the emergency plan and procedures.

Implement a specific course of action on the basis of previously established emergency plans and procedures, taking care to minimize doses that might be received as a result of this course of action.

Move to a location away from the controlled area and rehearse the planned course of action before entering the controlled area to implement the emergency plan.

Implement the planned course of action to the extent that training, equipment, the actual situation and authorizations allow; under no circumstances should the source come into contact with the hands or other parts of the body.

If the course of action taken is unsuccessful, leave the controlled area and consider the next course of action while maintaining surveillance of the controlled area.

Call for technical assistance, if necessary, from a qualified expert or from the manufacturer of the source and/or the gauging equipment, as appropriate. Such assistance may form part of the emergency plan and procedures, in which case it should be planned and agreed upon between the various parties in advance.

When the situation is brought under control and the source is safe, investigate the incident and estimate any doses received.

If personal dosimeters were worn, return these to the dosimetry service for rapid assessment.

Arrange for any damaged or malfunctioning equipment to be repaired by the manufacturer or a qualified expert before any reuse.

Prepare a report and notify the regulatory body, in accordance with regulatory requirements.

Quickly recognize an abnormal situation that might constitute an emergency.

Turn off the electrical power to the generator.

Inform the radiation protection officer of what has happened.

Perform a radiation survey to determine whether there is any residual radiation hazard.

Not move any equipment until details such as position, beam direction and exposure settings (tube voltage, current and time) have been recorded.

Not use the gauge until it has been examined and repaired by the manufacturer or by a qualified expert.

Estimate the doses that could have been received.

If personal dosimeters were worn, return these to the dosimetry service for rapid assessment.

Prepare a report and notify the regulatory body, in accordance with regulatory requirements.

A description of the emergency, with as much detail as possible of the equipment involved. The details should include model numbers and serial numbers wherever possible.

Environmental conditions at the time of the emergency, with particular reference to whether or not these conditions played any significant part in causing the emergency or affecting the outcome.

The specific cause(s) of the emergency.

Details of actions taken to regain control of the situation and to restore conditions to normal, with special reference to any actions that were notably beneficial or detrimental.

The personnel involved and their duties, tasks and qualifications.

An assessment and summary of the doses received by all affected individuals.

Corrective actions recommended with the aim of preventing similar emergencies in the future.

Lessons from managing the emergency.

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Installation of gauges;

Operation of gauges;

Transport of portable gauges;

Work at the client’s site with portable gauges;

Maintenance of gauges;

Disposal of disused sources and gauges.

Neutron generator or X ray generator failing to de-energize when operation is terminated;

Loss of shielding resulting in increased dose rates;

Damaged source resulting in the spread of radioactive contamination;

Missing, lost or stolen radioactive source;

Leaking source (e.g. as detected by a routine leak test);

Failure of a safety system (e.g. warning lights, shutter mechanisms);

Fire or explosion (work area, storage area, during transport);

Incidents during special procedures (installation, maintenance, calibration, removal);

Damaged transport container (for portable gauges);

Accident during movement or transport of portable gauges containing radioactive material.

The beta sources will give rise to bremsstrahlung radiation.

Some ²⁴¹Am gamma sources produce neutron radiation.

The neutron sources will give rise to gamma radiation.

Workers: Gauge operators, gauge maintenance personnel and other personnel present in the area.

Members of the public, including visitors to the site.

Safety incorporated in the design of the sealed source, the gauge and the gauging system as a whole;

Shielding provided by the gauge and any associated containers;

Demarcation of the gauge area with barriers and warning signs;

Safety and warning systems (shutters, interlocks, warning lights and other signals);

Design of special handling tools (for installation, maintenance and emergency procedures).

Safe working procedures, including local rules and permit-to-work systems;

Staff training;

Appointment of radiation protection officer(s);

Obtaining advice from a qualified expert;

Establishing a radiation protection programme, including the designation of controlled areas and supervised areas, and workplace monitoring and individual monitoring;

Periodic maintenance and servicing of nuclear gauges;

Periodic checks on the operation and effectiveness of safety systems;

Periodic safety audits of operations;

Establishement of dose investigation levels;

Procedures for leak testing of radioactive sources;

Inventories for radioactive sources and radiation generators, supported by periodic accountancy checks and records, and records of the movement of radiation sources.

The contractor did not discuss the job with the brewery or with the contractor’s qualified expert and had inaccurate information about the size of the gauges and the sources.

Alternative methods of work had not been considered.

There was doubt about whether the available workplace monitoring instrument was functional; when the batteries of the instrument were checked some days later these were found to be completely discharged.

Equipment holding radioactive sources needs, wherever possible, to be transported with the source undisturbed to suitable facilities before dismantling takes place.

Where removal of sources on the site is unavoidable, close liaison between all the operating organizations involved (and their respective qualified experts) needs to take place with a view to ensuring that adequate facilities are available for the work to proceed safely.

Local rules have to clearly and unambiguously state what needs to be done (or not done) if conditions change during the work.

Emergency procedures need to be incorporated into local rules, made known to relevant persons, and practised.

After source manipulations, appropriate monitoring needs to be undertaken. In situations such as this, contamination always needs to be considered possible; not just from the manipulation procedure, but also owing to degradation of the sources due to the environment in which they were used.

The operation of workplace monitoring instruments needs to be checked before each use (e.g. using a check source). Spare batteries have to be carried with the instrument.