Chapter 10 Radiation Safety
At HKUST, radioactive materials and irradiating apparatus are used for teaching and research purposes. These materials and equipment must be handled appropriately to avoid adverse effects to the users, the public and the environment. Adherence to the control guidelines summarized in this program will assure the safe handling of these items and minimize the exposure to radiation.
Hong Kong legislation requires that the use of radioactive materials and irradiating apparatus at workplaces, including tertiary institutions, be regulated by the Radiation Board of Hong Kong. Under the regulation, the use and storage of radioactive materials and irradiating apparatus on campus are closely regulated. The University has appointed a University Radiation Protection Officer (URPO) to oversee a comprehensive radiation safety program which will include controls on the purchasing, transport, storage, use and disposal of radioactive materials and irradiating apparatus. Furthermore, personnel registration, training, monitoring and medical surveillance will be addressed. Following the controls stated in this program will satisfy these regulatory requirements. Failure to comply with these requirements may not only jeopardize the health of staff and students but may also result in criminal prosecution of the offender.
The user must evaluate each task in which radioactive materials or irradiating apparatus are used to determine the associated risk. This evaluation must include a consideration of the properties and reactivity of any chemicals or siting and safety features of irradiating apparatus. Additionally, for radioactive materials, eventual disposal options and waste minimization techniques should be evaluated in the planning stage. Further, the tasks, materials and equipment involved should be reviewed by a knowledgeable person in advance of the operation.
Principal investigators/supervisors are responsible for establishing safe procedures and providing the protective equipment needed in handling radioactive materials or using irradiating apparatus. They must instruct their personnel as to the possible hazards, the safety precautions, waste handling, the consequences of an accident, and the actions to take in case of an accident. It is also his/her responsibility to assure that employees and students are held accountable for the materials and equipment they work with. In case of a job/program transfer or termination, employees or students must properly dispose of or transfer all assigned materials or equipment to another responsible party before leaving.
Employees and students are required to learn and understand the properties of the materials and features of the equipment they work with and to follow all precautions applicable to each task. In case of unexpected malfunctioning, damage, or injury, the employee/student should act to protect him/herself and others in the area. He/she should also report to the supervisor any unsafe or hazardous condition in the area.
The Health, Safety and Environment Office (HSEO) assists supervisors, employees and students in maintaining safe work areas by providing information on the hazardous properties of materials and equipment, recommending methods for controlling the hazards, and for monitoring the work environment. In addition, HSEO offers formal education and training courses on the recognition, evaluation and control of various safety hazards.
D. Radiation Use Authorization
IntroductionFor any radiation work involving the use of radioactive materials on campus, a “Radiation Use Authorization” (RUA) must be obtained prior to the actual operation.
Application ProceduresThe principal investigator should submit the Application Form (Appendix 10A of this chapter), duly signed and endorsed by the Department Head, to the University Radiation Protection Officer (URPO) of HSEO. A detailed review of the proposed project will be conducted which includes an inspection of the proposed workspace(s) and personal interviews with the lab technicians and the applicant if necessary.
Criteria for ApprovalThe criteria for approval (Appendix 10B of this chapter) are based on the Radiation Ordinance Chapter 303 and Radiation (Control of Radioactive Substances) Regulations. In addition to the requirements of the Ordinance and Regulations, the following are also required: (i) Training of personnel; (ii) Radiation monitoring of personnel and workplaces; (iii) Administrative, engineering and contamination controls; and (iv) Records and documentation.
Notification of RUA ApprovalThe original RUA is granted to the authorized user, and should be posted on the front door of the laboratory concerned. Copies are distributed to the concerned Department Head and Purchasing Office.
Renewal of RUAsRadiation Use Authorizations are valid for a maximum of one year. Each authorization will be reviewed, modified, and re-authorized on a yearly basis (Appendix 10C).
Termination of RUAsAny authorized user found to be willfully and/or negligently violating any of the campus regulations governing the use of radioactive materials or irradiating apparatus may have his/her authorization suspended or revoked by the Director of HSEO, and any radioactive materials or irradiating apparatus in his/her possession impounded or made inoperable. Committee decisions to revoke or suspend the use of radioactive materials or irradiating apparatus may be appealed to the VP-AB. The VP-AB will meet with the petitioner and HSEO staff to make a determination as to revocation or suspension.
Revisions and Amendments of RUAsIf a user finds that a revision of the RUA is required, he/she has to contact HSEO to request for the change (Appendix 10C). Items that require specific pre-approval via updating the RUA include any of the following:
- Changes in personnel.
- Use of radionuclides or compounds not listed on the authorization.
- Change of use location.
- Increase in use or possession limits
- Use of processes or procedures not previously authorized.
E. Registration of Users
An employee or student* is authorized to handle radioactive materials or irradiating apparatus provided that:
- He/she has registered with the URPO, and
- He/she has attended the radiation safety training courses**, and
- He/she has signed a statement that he/she has read this document and agrees to comply with its provisions.
Registration forms and acknowledgement statements can be obtained from the URPO.
* Students attending instructional classes and teaching laboratories do not need to register. However, they must follow the instructor’s directions. Students conducting independent research projects involving the use of radioactive materials or irradiating apparatus must register.
** A person who has not yet received the training may work under the close supervision of a trained person for a period of up to 3 months. Furthermore, one who has completed a similar course elsewhere may request to take an exemption examination, the passing of which will satisfy this training requirement.
F. Irradiating Apparatus and Their Control
An equipment is defined as an irradiating apparatus if it is intended to produce or emit or is capable of producing or emitting ionizing radiation at a dose rate in excess of 5 microsieverts per hour (5 uSv/h) at a distance of 5 cm from the accessible surface of the apparatus. Requirements for use of irradiating apparatus include room shielding protection, periodic radiation surveys and personnel monitoring. At HKUST the use of this type of equipment will be very limited. Contact the URPO for further details.
G. Purchasing of Radioactive Material and Irradiating Apparatus
Procurement of Irradiating Apparatus
- User MUST inform Health Safety and Environment Office (HSEO) prior to any purchases of irradiating apparatus. User must provide ordering information including name of the irradiating apparatus, vendor, catalogue number, functional specifications, and location of use.
- User must declare any purchases of irradiating apparatus in the Purchase Order (PO) or Departmental Purchase Order (DPO). PURO and HSEO will be notified automatically about such purchases. Upon receiving the notification, HSEO will submit an application for possession of irradiating apparatus in non-functional state, a P-licence, issues by the Radiation Board immediately. At this stage, user must put processing of the PO/DPO on hold until confirmation with HSEO for compliance with local regulatory requirement.
- While pending for approval of the P-licence application, HSEO will contact the vendor to clarify if the vendor possess a licence for sale of Irradiating Apparatus licence (Appendix 10I). With exception to any direct purchases from vendor that possess a licence for sale of Irradiating Apparatus licence, HSEO will handle the import licence application subsequent to the approval of the P-licence (Appendix 2) and logistics for delivery directly.
- Arrangement for delivery will be made only after the import licence for the apparatus is granted.
- HSEO will complete the arrival detail in import licence and PASS the import licence to the carrier for collection of the item from Customs and Exercise Office. The carrier will be reminded to return the import licence to the Trade and Industry Department for record.
- Upon receiving the item, user must report to HSEO the information about the serial number of the Control Panel Machine and/or the X-ray Tube Head.
- After the installation of the irradiating apparatus, HSEO will apply a licence for possession and use of IA in a functional state. At this stage, user can ONLY use the apparatus for commissioning and testing purposes. The apparatus can be used for normal/routine operation NOT UNTIL after the licence for possession and use of IA is granted.
Procurement of Unsealed Radiation Sources
- A valid RUA must be presented to the Purchasing Office prior to the ordering of radioactive materials. The amount of radioactive materials in the work area must be minimized. Never order more than what is actually needed.
- Ordering information must include radionuclide, chemical name, vendor and catalogue number, amount, user’s name and phone number and storage location of the radioactive material.
- A copy of each purchase order for radioactive material must be sent to the URPO.
- Packages arriving on campus should be initially checked for surface contamination to assure that no leakage has occurred during transit.
H. Transfer of Radioactive Materials
When any radioactive material arrives on campus, the receiving party has to notify the URPO. No radioactive material can leave campus without authorization from the Radiation Protection Officer (RPO) at the origin and also at the destination of the shipment. The user is responsible for notifying the URPO. The following information is needed for shipping radioactive materials:
- Name of persons shipping and receiving the radioactive material.
- Name and address of institution receiving the radioactive material along with written authorization from the RPO at the destination.
- Desired date of transportation.
- Mode of transportation.
- Name of compound and radionuclide.
- Radioactivity (Curie or Becquerel) to be shipped.
- Physical state of compound.
- Stock number.
For detailed information on packaging, labeling and necessary paperwork, contact the URPO.
I. Inventory of Radioactive Material
A centralized inventory of radioisotopes will be maintained by the URPO. Each user is responsible for keeping individual records to account for the arrival, transfer, utilization and disposal of the material. A copy of this record must be submitted to the URPO at the end of each school term to update the central inventory. Standardized inventory forms (Stock Record in Appendix 10D and Inventory Record Appendix 10E) may be obtained from the URPO.
J. Storage of Radioactive Material
Radioactive materials must be stored in lockable metal cabinets or refrigerators at designated locations within the lab. These controlled locations should be protected against unauthorized access. Proper storage of radioactive materials in the laboratory includes providing sufficient shielding to reduce the radiation to the lowest level possible, and preventing the release or spillage of radioactive material.
- A 32 P storage location should be checked with a gamma survey meter for the production of bremsstrahlung radiation. To reduce such radiation, 32P-labeled materials should be stored in plexiglass containers, which are then surrounded by lead sheet.
- Once opened, vials containing unbound radioiodine should not be stored in refrigerators, freezers, or cold rooms, but in fume hoods and every effort should be made to keep these vessels tightly sealed.
- Shielding should be arranged as to avoid blocking fume cupboard rear exhaust slot or hood face.
- Radioactive materials storage locations, such as refrigerators, freezers and hoods should be labeled with “Caution: Radioactive Materials” signs. Storage containers and waste containers also should be labeled with the “Radioactive Materials” signs.
K. Use of Radioactive Material
- Access to facilities used for the handling of radioisotopes shall be restricted to authorized personnel only.
- Eating, drinking, smoking and storing food in laboratories are prohibited. Inadvertent ingestion of radioisotopes is a major source of potential exposure in a medical or research environment.
- Work with volatile radioactive materials, e.g. Na125 I and 3 H2O and those procedures giving rise to radioactive aerosols (e.g. sonicating, homogenizing) should be performed in a fume hood. TEDA charcoal filters should be installed in hoods used for iodinations to trap free iodine. Minimum shielding raised from the bottom of the hood should be used to prevent blocking the air flow and negating the effectiveness of the fume hood.
- Wear protective clothing (lab coat and gloves, etc.). Lead aprons are not recommended since they may protect the individual using it but not the other fellow workers. They are heavy to wear and may get contaminated. Lead aprons should not be used for work with 32P because they will create bremsstrahlung radiation that might increase the total dose received by the worker unless the apron has sufficient thickness to absorb that bremsstrahlung.
- Work involving the use of radioisotopes must be conducted only in designated areas within the lab. Cover work surfaces with plastic backed absorbent spill paper, glass or trays in such a way that any spill may be contained.
- Use a survey meter to verify that shielding is adequate. 32P work must be conducted behind plexiglass shields.
- Rooms, areas within rooms and vessels that contain or store radioactive materials should be labeled. Ask your DSO for the appropriate type of labels.
- In a sealed source the radioactive material is encapsulated. If the capsule is defective, some of the radioactive material may leak. Therefore these sources should be tested upon arrival for leakage by wipe test and thereafter at intervals not greater than six months. The test is done by either wipe testing the source or a surface or material that has been in contact with the source. The URPO will arrange for these wipe tests. The removable contamination limit commonly accepted is 200 Bq (0.005 uCi) for all sources.
L. Exposure Evaluation
Persons performing radioiodinations should get an iodine uptake evaluation within 2 hours after completing the experiment. This evaluation must be prearranged with the RPO no later than 48 hours prior to the experiment.
Individuals involved in operations which utilize large amounts of an isotope at any one time (e.g. more than 3.7 GBq (100 mCi) of 3H in a non-contained form, other than metallic foil) should have a urinalysis performed within 24 hours of a single operation and at weekly intervals for continuing operations. This test must be prearranged with the URPO no later than 48 hours prior to the experiment.
Dosimeters should be used when working with neutrons, high energy beta particles, gamma and x-rays. Consult the URPO for the appropriate choice of dosimeters. The most common dosimeters are whole body dosimeters distributed to all workers being monitored and ring dosimeters used for special applications. Use a ring dosimeter if working with large amounts of material [e.g. 1.85 GBq (50 mCi) of 32P] or when starting a new procedure to evaluate the possible impact on the cumulative dose. Obtain these dosimeters from the URPO.
Return used dosimeters to the URPO at monthly intervals for analysis. The URPO will notify users of the measurements.
Various real-time survey instruments may also be used to determine exposure. Please consult the URPO for the appropriate models of survey meters to be used for specific radionuclides with specific energies.
M. Contamination Survey
The objective of a contamination survey is to indicate whether levels of radiation and/or contamination are satisfactory for continuing the work with ionizing radiation, detecting breakdowns in controls or systems and detecting changes in levels of radiation. Laboratories and other areas in which work with unsealed radioactive materials is undertaken should be monitored for surface contamination upon completion of experiments and on a regular basis. The frequency of these survey will be decided by the URPO based on the radionuclides, amount utilized and the frequency of use. Contamination may be fixed or removable and can be detected by direct monitoring and swipe testing respectively.
At periodic intervals the entire laboratory room should be checked for contamination by the URPO and records of these tests should be kept. The frequency of these checks will be decided by the URPO based on the isotopes, amounts utilized, and the frequency of use.
Direct MonitoringDirect monitoring is conducted to detect fixed contamination and external radiation arising from gamma radiation and strong betas such as 32P. It should be monitored with a hand-held GM survey meter at 2.5 to 5 cm from surfaces with a scanning speed of 5 - 10 cm/sec.
Areas with fixed contamination should be covered with some shielding materials to avoid unnecessary personnel exposure if the levels warrant it.
Indirect Monitoring (Swipe Test)Indirect monitoring is to detect contamination whenever the use of hand-held survey meter is not practical and also to distinguish “fixed” contamination from “removable” contamination. A protocol of swipe testing is attached (Appendix 10F).
Acceptable Removable Surface Contamination Level
Radionuclide Acceptable Removable Surface Contamination Level 125I, 131I 20 dpm/100 cm2 3H, 14C, 32P, 33P, 35S, 45Ca
1,000 dpm/100 cm2
N. Radioactive Waste Management
All waste contaminated with radioactive materials must be disposed of as radioactive waste through HSEO . HSEO will pick up radioactive waste from each lab on a regular basis and bring them to a centralized accumulation area for disposal. For materials with short half-lives, they may be stored until the activities drop below levels acceptable for disposal as municipal waste. Other materials may be disposed of by shipping back to the manufacturer or to the Hong Kong Radiation Board.
Waste containing toxic chemicals and/or biohazards must be inactivated prior to disposal as radioactive waste; however, these materials may not be autoclaved unless the volatilized radioactivity may be trapped in a filter thus preventing contamination of the autoclave.
All radioactive liquid wastes, including contaminated rinses of glassware, must be collected as radioactive waste unless approved by the URPO. Similarly, do not discard radioactive liquids down the drain since they will contaminate building plumbing, unless approved by the URPO. Sewage from the University will be monitored by the Environmental Protection Department for illegal discharge of hazardous materials.
Appropriate radioactive waste containers will be supplied by HSEO. Laboratories should segregate their radioactive waste according to radionuclide and form (see below), and tag it with a radwaste label provided by HSEO. Fill out the radwaste label accurately. Disposal decisions concerning each bag, bottle, box, etc. to be picked up are based on the information that appears in that label. Place the waste in the designated location of the laboratory for pick-up by HSEO.
Solid WasteSolid waste should be packed in plastic bags. It should not contain pourable liquids or animal carcasses. Needles, Pasteur pipettes and other sharp objects should be placed in a puncture-proof sharps container to protect the waste handler and to prevent piercing the waste bag.
Stock VialsRadioactive stock vials should be placed in a designated container provided by HSEO. These vials may contain small amounts of liquid.
Lead ShieldingLead pegs and shielding should be separated from their plastic holders and placed in a bucket provided for lead disposal. Once the radioactive symbols have been removed or obliterated, the plastic holders may be placed in the trash if they are not contaminated. The lead may be recycled. Otherwise, it may be disposed of as a solid chemical waste at an approved landfill.
Liquid WasteLiquid waste should be collected in plastic holders provided by HSEO. For radioiodine waste, use bottles containing sodium thiosulfate (0.1 M final concentration) to bind the free iodine. Shielding may be necessary. Pathogenic materials should be inactivated with an appropriate disinfectant solution prior to disposal. (Note: Do not add bleach to materials containing radioactive iodine. This will result in the release of the iodine.) Experience has shown that usually 95% of the radioactivity is disposed of as liquid waste. Aqueous liquids should have a pH between 6 and 9 and organic liquids should be segregated according to isotope and chemical name. Do not mix chemicals coming from different processes. The chemical names and percentages of all the chemical components, including solvents, should appear on the hazardous waste label.
Liquid Scintillation VialsLiquid scintillation vials should be segregated by radionuclide and returned to their boxes or trays for collection. On the radwaste label, indicate the brand name of the scintillation cocktail used. This will facilitate segregation of different types of cocktails (e.g. flammable and biodegradable) by waste handlers.
Biological WasteSolid biological material includes animal carcasses, solid excreta and wet bedding. Carcasses containing up to 1.85 kBq/g (0.05 mCi/g) of 3 H and/or 14 C may be disposed of without regard to its radioactivity, preferably by incineration. All other biological wastes should be placed in a specially-prepared and approved five-gallon container. These containers have a layer of vermiculite and a plastic bag containing lime. Make sure that all the biological materials are in contact with the lime. When the drum is full or not needed any more, seal the bag with tape and request a pickup by HSEO.
O. Spill and Decontamination
- Notify all personnel in the room and ask them to leave the area of the spill immediately .
- Notify supervisor.
- Call general emergency contact number (8999).
- Drop absorbent paper on spill;
- If iodine liquid is spilled, cover with sodium thiosulfate. (Refer to Appendix 10G for details)
- If gas or vapour is released, use local exhaust ventilation to prevent the spread of the materials to other parts of the building.
- External contamination:
- Remove all suspected contaminated clothing, place in a plastic bag and seal it. While washing with a detergent, check skin for contamination with a portable survey meter or by wipe tests, depending on the isotope. Do not scrub the skin with a brush because it generates aerosols.
- Clean skin contaminated with 32 P with household vinegar.
- In case of contamination with free iodine, apply a paste of sodium iodide to contaminated area and let it react with the free iodine, then wash the area with a detergent. A dose of 300 mg of saturated solution of potassium iodide is recommended to prevent a thyroid burden.
- Report to the URPO to arrange for an iodine uptake evaluation.
- Internal contamination:
Report to the URPO.
- Wear gloves and protective clothing. Start at periphery and work toward area of highest level of contamination. For surface decontamination, use soap and water and cleaners appropriate to the particular radiolabelled compounds and carrier chemicals (dilute HCL, MicroTM, AlconoxTM, CountOff TM, RadiacwashTM, or other). Do not use scrub brushes which will produce aerosols and spread contamination. Survey continuously. Permit no one to resume work in the area until a survey is made and no contamination is found above background level.
- In case of free iodine contamination, apply a paste of sodium iodide to the contaminated area and let it react with the free iodine, then wash the area with a detergent. Do not use acids when cleaning a spill containing free radioiodine because the low pH will cause more volatilization of the radioisotopes.
Report accidents/incidents involving radioactive materials to the URPO and fill out an Incident/ Accident Report Form.
P. Non-ionizing Radiation Safety
Equipment Emitting Non-ionizing Radiation
Many research activities on campus may involve the use of equipment that generates non-ionizing radiation (NIR) and electric and magnetic fields. Nuclear Magnetic Resonance (NMR), plasma etcher, and high power UV light sources are some of the typical examples of equipment which generates NIR and fields. This equipment must be handled appropriately to minimize users’ exposures to NIR.
Users are required to notify HSEO for purchase of new NIR and fields generating equipment designed for research purposes. Site inspection and exposure survey for NIR and the fields will be conducted to establish appropriate control measures for the equipment and procedures during the initial setup. Users who may work with NIR sources should attend safety training prior to the start of the experiment. A list of NIR and fields sources that require evaluation can be found in Appendix 10H.
Managing Potential Exposure to NIR Emitted by Mobile Telephone and Paging Antennae on Campus
Mobile phone and paging antennae are low power emitters of electromagnetic field. These base stations are generally mounted on rooftops of buildings and may cause potential overexposure when residents and workers approach these base stations on the rooftop. To prevent overexposure to the electromagnetic fields emitted by the antennae, warning sign should be posted at locations where overexposures may likely to occur, and maintenance personnel should be briefed about the exposure risk to electromagnetic fields while working on the rooftop.
All antenna installation must comply with the “Code of Practice for the Protection of Workers and Members of the Public against Non-ionizing Radiation Hazards from Radio-transmitting Equipment” issued by the Office of the Telecommunications Authority (OFTA), Hong Kong. Proposal for new installations of any outdoor and indoor antennae on campus must be submitted to HSEO via CMO or Campus Development Office (CDO) for evaluation. The proposal must clearly indicate the location where the new system is to be installed and provide detailed specifications of the antenna system for assessment. HSEO will conduct site inspection and exposure survey to ensure the new installations comply with the applicable safety standards and arrange periodic exposure surveys to ensure these requirements continue to be met.
Appendix 10A & C Radiation Use Authorization - Radioactive Materials Application Form
Appendix 10B Radiation Use Authorization - Criteria for Approval (Radioactive Materials)
Appendix 10D Unsealed Radioactive Material Stock Record
Appendix 10E Unsealed Radioactive Material Inventory Record
Appendix 10F Dry Swipe Test - Protocol
Appendix 10G Emergency Response Procedures for Iodine-125 Spill
Appendix 10H Non-ionizing Radiation Sources that Require Evaluation
Appendix 10I Flow Chart Procedures of Irradiating Apparatus Procurement