AEC RADIATION SAFETY GUIDE SAFE USE OF INDUSTRIAl DEVICES CONTAINING RADIOACTIVE SOURCES

Transcription

1 AEC RADIATION SAFETY GUIDE SAFE USE OF INDUSTRIAl DEVICES CONTAINING RADIOACTIVE SOURCES AEC-RSG 2.1, 2015

2 FOREWORD The Atomic Energy Council (AEC) was created by the Atomic Energy Act No.24 of 2008 with a mandate to regulate the peaceful applications of ionising radiation; to provide for the protection and safety of individuals, society and the environment from the dangers resulting from ionising radiation; to provide for the production and use of radiation sources and the management of radioactive waste; to provide for compliance with international safety requirements for the use of ionising radiation, radiation protection and security of radioactive sources; and for other related matters. This guide was developed to assist the Registrant/Licensee to follow systematic procedures which will facilitate an effective implementation of the provisions of the Atomic Energy Regulations, This guide was prepared by the Atomic Energy Council with the assistance of the International Atomic Energy Agency. 2

3 PREFACE In the frame work of the IAEA-Country Project Strengthening the National Regulatory Infrastructure and developing a National Nuclear Security System to Control radiation Sources and Occupational Exposure, some of the essential elements were developing of regulatory capability for licensing and inspection, enforcement and occupational radiation protection, medical exposure control and public exposure control. The need to prepare supporting documents such as codes of practice, standards, guides and relevant documents was recognized. This guide was prepared basing on the following hierarchy: Legislation-The Atomic Energy Act No.24 of 2008 that established the Atomic Energy Council and its powers and functions Regulations- The Atomic Energy Regulations, 2012 which were made for the better carrying into effect of the provisions of the Act Radiation Safety Guides which provide guidance for regulators, registrants, licensees and stakeholders for complying with the regulations as required by s.74 of the Act. The recommendations in this guide are intended only for all persons/organisations involved in the use/handling of radiation sources. They include the regulatory staff, employers, licensees, registrants, management bodies and their advisers, Radiation Safety Committees, Radiation Safety Officers and Radiation Protection Officers Approved by... Mr. Deogratias Noah Luwalira Secretary & CEO, AEC Dr. Akisophel Kisolo Chairman, AEC 3

4 TABLE OF CONTENTS FOREWORD 2 Preface 3 Authorisation 5 Definitions INTRODUCTION ADMINISTRATIVE REQUIREMENTS OPERATING PROCEDURES General Requirements Installation and Maintenance Installation Cleaning and Mechanical Maintenance Wipe Tests EQUIPMENT SPECIFICATIONS Structural requirements Dose rates outside the device containing sealed source Shutter Device labels and markings TRANSPORT STORAGE OF DEVICES CONTAINING SEALED SOURCES DISPOSAL OF DEVICES CONTAINING SEALED SOURCES Notifying AEC EMERGENCY PROCEDURES 16 REFERENCES 17 Appendix A 18 Contributors 19 4

5 AUTHORISATION Under section 74 of the Atomic Energy Act No.24 of 2008, Atomic Energy Council (AEC) issues general instructions, known as Radiation Safety Guide, concerning the use of radiation and operations involving radiation. The Atomic Energy Act stipulates that the authorised person for a radiation practice is responsible for the safety of the operations. The authorised person is obliged to ensure that the level of safety specified in this Radiation Safety Guide is attained and maintained. 5

6 DEFINITIONS Approved means approved by the AEC. Authorisation means licence granted in writing by the AEC to a licensee who has submitted an application to carry out a practice. Authorised person means a person issued an authorisation under section 37 of the Atomic Energy Act No.24 of Defence in Depth means the application of more than a single protective measure for a given safety or security objective such that the objective is achieved even if one of the protective measures fails. Dose means a measure of the radiation received or absorbed by a target. Dose rate means dose received or absorbed by a target per unit time. Emergency plan means a set of procedures to be implemented in the event of a radiation accident. Environment means the physical factors of the surroundings of human beings, animals and plants including land, water, atmosphere and their interactions. Exposure means being subjected to ionising radiation. Monitoring means the measurement of a dose or contamination for purposes related to the assessment or control of exposure to radiation or radioactive substances, and the interpretation of the results. Practice means any human activity that adds or may add to the exposure of personnel or the members of public. Radiation means ionising radiation. Radiation Safety Officer means a person appointed and approved under section 36 of the Atomic Energy Act No.24 of Radiation worker means any person, whether full time, part time or temporarily employed, who can be exposed to annual dose in excess of 1 msv, and has recognised rights and duties in relation to occupational radiation protection. Radioactive material means any matter or substance containing one or more radionuclides, the activity or concentration of which is sufficiently intense to entail a significant risk of disability or disease to any body or organ in exposure, whether external or internal, and whether continuous or total. Radioactive source means radioactive material that is permanently sealed in a capsule or closely bonded in a solid form. Sealed source means a source consisting of radioactive material firmly incorporated in a solid of effectively inactive materials, or sealed in an inactive container of a strength sufficient to prevent, under normal conditions of use, any dispersion of radioactive material and any possibility of contamination. Security means measures to prevent unauthorised access or damage to, and loss, theft or unauthorised transfer of radioactive materials; Source means anything that may cause radiation exposure, such as by emitting ionising radiation or releasing radioactive substances or materials; 6

7 1.0 INTRODUCTION This radiation safety guide presents the radiation safety requirements for devices containing radioactive sealed sources, and for their installation and use. The requirements of this guide apply in particular to industrial uses of such devices. 1.0 Industrial devices containing sealed sources are generally used in the same premises of an industrial plant where continual work is done. Workers will not generally need to be classified as radiation workers, nor will any monitoring of radiation exposure or classification of work areas be required, provided that the use of devices containing sealed sources is arranged in accordance with the requirements of this guide. The use of sealed sources in industrial radiography is also governed by AEC Radiation Safety Guide 2.2, 2015(AEC-RSG 2.2, 2015). 7

8 ADMINISTRATIVE REQUIREMENTS 8 a) Anyone planning to start industrial operation involving sealed sources must notify AEC for pre-approval of the practice. b) An application for license to possess and use devices containing sealed sources with an activity in excess of exemption values shall be submitted to AEC by the authorised person. An application must be submitted for each such device. c) An application for renewal of license has to be submitted no later than three months prior to its expiry. d) All changes to the practice carried out under the license must be submitted in an application to the AEC. e) The applicant shall nominate a Radiation Safety Officer (RSO) for approval by the AEC. Should the approved RSO be changed at any stage, an application to nominate a new RSO must be submitted to the AEC in writing. f) The authorized person, herein referred to as the licensee, shall provide an inventory of radioactive sources to the AEC at periodic intervals indicated on the license. g) In case of incidents and accidents in the use of devices containing sealed sources, the licensee shall notify AEC without undue delay. AEA, 2008, Sections 34, 35, 36, 50, and 51. AER, 2012, Regulations 15, 30, 44 and Schedule 2.

9 OPERATING PROCEDURES 3.1 General Requirements a) The RSO shall ensure that all personnel handling or working near sealed sources are fully aware of the associated radiation hazard and are familiar with correct work procedures. b) A radiation warning sign must be posted in the vicinity of the device containing the sealed source to discourage loitering in the area. c) As a general rule, operations, for non radiation workers, shall be organised in a manner that keeps radiation exposure As Low As Reasonably Achievable (ALARA) and ensures that the annual dose does not exceed 1 msv. To ensure this, attention must be paid to the following matters: i. No person may remain for longer than one hour per day in an area where the dose rate arising from a radiation source is greater than 5μSv/h. ii. If activities are undertaken in an area where the dose rate arising from a radiation source is greater than 5μSv/h, then specific instructions must be prepared for the work in order to ensure that the annual dose does not exceed 1 msv. d) When a device containing a sealed source is not in use, (e.g. a production line is temporarily closed or a tank is emptied for maintenance) the source must immediately be secured in the shielded position (i.e. beam off position) and where appropriate placed in storage. e) Installation or any relocation of a fixed device containing sealed sources must be done under the supervision of the RSO, and the AEC must be informed of the change in writing. f) The licensee shall keep records of all movements of portable devices containing sealed sources. g) Every practice using sealed sources must have an appropriate radiation monitor. AEA, 2008, Sections 36 and 55. AER, 2012, Regulations 30,35,37,63,65 and schedule 3. 9

10 3.2 Installation and Maintenance To ensure correct operation of devices containing sealed sources, these devices should be installed and maintained in accordance to manufacturer s instructions and AEC guidance. AER, 2012, Regulation Installation Fixed devices containing sealed sources must be installed in a manner that prevents exposure of any part of the body to the primary beam of the radiation source. If necessary, a cage or screen must be erected around the device to restrict access to the primary beam. Cages or screens however, must be erected in such a way that source containers are visible and shutter mechanisms are easily accessible. AEA, 2008, Section 63. AER, 2012, Regulation Cleaning and Mechanical Maintenance a) Maintenance work which does not involve the source directly (e.g. fixing of electronics, working on the detector, relocation of equipment, or the performance of non-related tasks in the vicinity of the device containing sealed sources) should be performed by competent personnel under the supervision of the RSO. The RSO should evaluate the potential radiation hazard and give advice on any precautionary measures that need to be taken. b) Maintenance work which directly involves the radioactive source (e.g. replacing defective sources, working on the shutter mechanism, etc.) should only be undertaken by registered radiation workers who are authorised by AEC to perform such work.during such maintenance operations dose rate checks should be carried out in the areas of operation to determine doses received by whole body or extremities. c) The licensee must keep records of all maintenance work. AEA, 2008, Sections 36 and 63. AER, 2012, Regulations 30, 34 and Wipe Tests Wipe tests should be done by a competent person under the supervision of RSO. Refer to Appendix A for additional information. 10

11 EQUIPMENT SPECIFICATIONS The requirements in this section adhere to ISO 7205 and IEC standards on devices containing sealed sources. AER, 2012, Regulations Structural requirements a) The principal structural requirements are as follows: i. The activity of all sealed sources must be optimized ii. The structure of the radiation device must minimise the radiation dose that is sustained in operating and servicing the equipment. iii. The device must be made of materials that withstand the ambient and extreme conditions that the source may be exposed to. iv. The device must be designed to ensure that the sealed source remains in its radiation shield even during a fire. The protective ability of the shielding should not be substantially impaired in a fire. v. The sealed source must be secured in the device with a seal or lock. vi. The device containing the sealed source should be collimated to minimise the size of the primary beam. vii. The detector utilised in the device must be selected to enable the use of a radiation source of the lowest possible activity. viii. The equipment must be designed to enable safe and secure transportation. AER, 2012, Regulations 21 and Dose rates outside the device containing sealed source a) The dose rates in the vicinity of devices containing sealed source (other than in the primary radiation beam) may not exceed the following values under standard ISO 7205 for equipment classification xx 2323xx x x: or IEC class 5: i. 500 μsv/h at a distance of 5 cm from the surface of the equipment ii. 7.5 μsv/h at a distance of 1 m from the surface of the equipment. b) If the use of devices with some other classification is desired, then the radiation safety requirements for its use shall be specified when issuing the license. c) The above maximum dose rates shall not apply to industrial radiography devices. AER, 2012, Regulation 64. AEC Radiation Safety Guide

12 4.3 Shutter a) The device shall have a shutter enabling the sealed source to be fully shielded when necessary. In special cases a device with no shutter may be approved for use if its structure and shielding prevent the radiation beam from exiting the device, or if the properties and manner of operation of the device achieve the same safety standard as a device that is fitted with a shutter. b) The shutter shall be of reliable construction and it must function under all operating conditions. It must be possible to close the shutter without using tools. c) The source shielding must include a lock enabling the shutter to be locked in the beam off position. The shutter should not be locked in the beam on position unless there is a special reason for so doing, having regard to the purpose of the device. It must not be possible to open the lock using a substitute for the key. d) The radiation device must be labelled to show the shutter positions. Use of colours as an additional indicator is recommended. If the device has several shutters, then each shutter shall have a position indicator of its own. e) Electrically or pneumatically controlled shutters must be reliable and must close automatically in the event of a power failure or loss of air pressure. No separate shutter lock is required in such cases. f) Devices with a remote-controlled shutter must include shutter position indicator lights. These lights must be directly controlled by movements of the shutter. The beam off indicator light must only show when the shutter is completely closed. The indicator lights must indicate open if the shutter is not fully closed. 4.4 Device labels and markings The device must have a metallic label bearing the radiation warning sign, radionuclide, activity, the date when this activity was determined, source serial number, the device manufacturer and model. The labels must be durable and legible. 12

13 TRANSPORT Radioactive sources used for industrial radiography must be transported in accordance with the requirements of the current edition of Regulations for the safe Transport of Radioactive Materials published by the IAEA, as well as relevant sections of the AER, 2012 and guidance from the AEC. IAEA, 2009, Regulations for the safe Transport of Radioactive Materials TS-R.1. AER, 2012, Regulations and Schedule 7. 13

14 6.0 STORAGE OF DEVICES 6.0 CONTAINING SEALED SOURCES a) Any devices containing sealed sources which are not required for immediate use or which have been removed from service for any reason should be placed in storage. A store for devices containing sealed sources should, where possible, be reserved for that purpose only so that personnel are not needlessly exposed to ionising radiation. b) The radioactive source store should be constructed according to the provisions of the atomic energy regulations and the following additional requirements: i. The materials used in the construction of the store should be strong and durable. ii. The store should be secure, lockable and under the control of designated person. iii. For categories 1 and 2 sealed sources, the principle of defencein-depth should be applied. The additional security measures should include measures such as but not limited to; electronic remote surveillance, twenty four hour guard, interlocks. iv. Dose rates outside the store must not exceed 10 µsv/h. v. The store should be located so that the annual exposure in any occupied area is as Low as Reasonably Achievable and well under the annual dose of 1mSv. vi. The store should not be located close to or be used to house explosives, combustible or corrosive materials. vii. The store should have a radiation warning sign. The radiation warning sign should include the text RADIOACTIVE MATERIAL. The warning sign should also contain contact details of the designated person in control of the store or the RSO. viii. All devices containing sealed sources being brought into the store should have the shutter controls locked in the beam off position. This should be checked by monitoring with a dose rate meter. ix. No devices containing sealed sources should be stored in any domestic premise. x. An inventory of stored sources and store plan should be maintained and kept in the store. c) Temporary storage facilities in the field must comply with storage requirements b.ii, b.iv, b.v, b.vi, b.vii and b.ix. Category 1 and 2 sources should not be stored in temporary storage unless 24 hour guards are present. AEA, 2008, Section 56(2). AER, 2012, Regulation

15 7.0 DISPOSAL OF 7.0 DEVICES CONTAINING SEALED SOURCES a) During purchase of the devices containing sealed sources, the licensee shall enter into an agreement with the supplier/manufacturer that the radioactive sources shall be taken back to the supplier/manufacturer when no longer needed. b) The licensee shall not dispose off a sealed source, or device containing a sealed source, without the authorisation from AEC. Dispose herein includes selling, lending, donating, exchanging, as well as returning of the device to the supplier. c) An application to dispose devices containing sealed sources must be submitted to the AEC. Where no clear disposal route exists the licensee has a responsibility to store the sealed source until a disposal route has been established and approved by the AEC. 7.1 Notifying AEC a) AEC must be notified without delay and not later than 24 hours of: i. Any incident involving the use of radiation that is substantially detrimental to safety at the place where the radiation is used or in its environment. ii. The disappearance, theft or other loss of a radiation source such that it ceases to be in the possession of the licensee. iii. Any other incident and accident essential to the safety of workers or the environment. b) AEC must be notified immediately of any accident endangering life of the workers, members of the public or result in the contamination of the environment. Examples of such accidents include, but are not limited to, loss of device with category 1 or 2 radiation source, loss of structural integrity of the device and containment for the radioactive source resulting in spread of radioactive material. c) The first notification of an incident and accident (normally by telephone) must state the following details: i. the responsible person (licensee) and the RSO. ii. the name and contact details of the person reporting the incident or accident. iii. the time and place of the incident or accident. iv. a description of the incident or accident. v. details of any persons involved and their possible radiation exposure. vi. the immediate measures taken. d) In addition to the above details, a written report must also be submitted to AEC within 15 days from the date of occurrence of the incident or accident. The report should give an account of the causes and consequences of the incident or accident (particularly of possible radiation exposure or contamination) and of the measures taken to prevent future corresponding incidents/accidents. AEA, 2008 Sections 55(a,b). AER, 2012 Regulations 16, 64-1(f), 66(2,) 83 and Schedule 1 form 7. 15

16 EMERGENCY PROCEDURES a) Licensee must identify in advance the possible incidents and accidents associated with the use of devices containing sealed sources. Examples of possible incidents and accidents arising in the use of devices containing sealed sources include but not limited to loss of source and exposure of workers to the primary beam during service work. b) The licensee must plan and implement operations in a manner that minimises the likelihood of incidents and accidents. Steps must nevertheless be taken to prepare for possible incidents and accidents by such means as issuing emergency plans for all incidents and accidents. c) These emergency plans should include: i. Persons to implement the emergency plan. ii. Equipment and its availability to implement the emergency plan. iii. Persons/organisations to be notified at various stages of implementation. iv. Procedures to bring the situation back to normal. d) Training should be provided to all relevant personnel and the emergency plan should be practiced through emergency exercises/drills. e) The emergency plan should be periodically reviewed and updated. AEA, 2008, Sections 59(2), 60, 61 and 62. AER, 2012, Regulations 67,68, 69 and

17 REFERENCES 1. Atomic Energy Act No 24 of Atomic Energy Regulations, Report on the Applicability of International Radiation Protection Recommendations in the Nordic Countries, Stockholm, Code of Practice for the Safe Use of Radiation Gauges, NH & MRC, Canberra, Australia, Working Safely with Nuclear Gauges, Atomic Energy Control Board, Canada. 6. Safe use of industrial gauges GAUGE 7 December South African Government Gazette no February Code of Practice for the Safe Use of Sealed Radioactive Material in Industry, NRL, 9. Christchurch, New Zealand, o0ocode of Practice GAUGE 8 December

18 Appendix A a) In a wipe test, do not wipe the source directly. A moistened pad of tissue or cloth is used to wipe around any area from which radioactive material might leak if the source was damaged. b) During and after wiping, the pad should be handled with tweezers or tongs. Make sure not to put your hands, or any part of your body, in the primary beam. c) After wiping, the pad should be placed into a plastic bag which should be sealed and checked for gross contamination using a contamination monitor or dose rate meter. The meter should be set to its most sensitive range and used in an area well away from devices containing sealed sources to minimise background radiation. d) If any contamination is found on a wipe, all work in the immediate vicinity of the device containing the sealed source MUST cease and the AEC must be informed immediately. e) The wipe pad should be retained in the plastic bag until further instructions from AEC. On no account should it be sent anywhere by mail or courier. Nobody must leave the place of work as they may have been contaminated with radioactive material. They must await the arrival of representatives of AEC or specialist services authorised by the AEC. f) The results of all wipe tests must be recorded on form, and must be available for inspection purposes NOTE: Care needs to be taken with sealed sources which emit low energy radiation. The source may have a thin window close enough to be contacted in a wipe test. Directly wiping the window could cause significant damage to the window or the surface of the source. 18

19 CONTRIBUTORS Akisophel Kisolo Deogratias N Luwalira Joseph Kigula Mugambe Rosemary Byanyima Maxwell Otim Onapa Richard Oriada Dan Kiguli Natharius Nimbashabira Deo Sekyanzi Moses Katumba Evans Ogwal Bonny Abal Charles Sekyaya Abdul Byamukama Chairman, AEC Secretary & CEO, AEC Council Member, AEC Council Member, AEC Council Member, AEC Technical Committee, AEC NEMA Radiation Protection Officer, AEC Radiation Protection Officer, AEC Radiation Protection Officer, AEC Radiation Protection Officer, AEC Radiation Protection Officer, AEC Radiation Protection Officer, AEC Radiation Protection Officer, AEC 19

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