Health and Safety
GENERAL STATEMENT OF POLICY
Our policy is to provide and maintain safe and healthy working conditions, equipment and systems of work for all our employees and students and to provide such information, training and supervision as they need for this purpose. We also accept responsibility for the health and safety of other people who may be affected by our activities.
The allocation of duties for safety matters and the particular arrangements which we will make to implement the policy are set out below.
This statement of Safety Policy is based on the requirements of The University of Hong Kong's Statement of Safety Policy (S5/381 revised) which we fully support. The policy will be kept up to date, particularly as the department changes in nature and size. To ensure this, the policy and the way in which it has operated will be reviewed every year.
The Head of the Department of Physics
Date ...............................June 2010........................................................
RESPONSIBILITIES OF STAFF AND STUDENTS
1. The Head of the Department of Physics has overall and final responsibility for health and safety in the department.
(a) He/she is responsible to ensure that appropriate safety standards and procedures are established, adopted, and followed.
(b) To ensure the health and safety of the staff and students, the Head will arrange adequate resources in the annual budget to provide for their health and safety whilst at work.
(c) In addition, the Head is responsible to ensure that safe and healthy working conditions are maintained.
(d) The Head will make provisions for and arrange for all level of staff to receive adequate and appropriate training on safety and health matters. He/she will inform new members of the department of the safety policy, standards, and procedures.
(e) The Head of the department is responsible to enforce the safety policy and safety practices in the department.
(f) The Head will appoint a Departmental Safety Representative, Departmental Radiation Safety Representative, and Fire Warden and define their duties.
2. The Departmental Safety Representative will aid and assist the Head in his/her safety duties to ensure that all measures designed to safe guard the health and safety of each individual are put into practice. The Departmental Safety Representative also has responsibilities:
(a) To inform the Head and the university Director of Safety of any special hazards in, or new hazards about to be introduced into the department.
(b) In consultation with the Director of Safety, to promote, plan, and conduct a regular programme of safety inspections to ensure that means exist for all equipment to be maintained and used in a safe condition.
(c) To ensure with the assistance of the Director of Safety that First Aid and safety facilities are properly maintained.
(d) To ensure that accidents are reported promptly in accordance with University procedures and to report any case of non-compliance to the Head.
(e) To recommend accident prevention measures to the Head as and when necessary.
(f) To maintain liaison with the Director of Safety and the Director of University Health Service.
3. The Departmental Radiation Safety Representative will take the responsibility to ensure the safe use of all radioactive sources, including lasers, x-rays, and other irradiating apparatus in the department. He/she also has responsibilities:
(a) To register all radioactive sources in the department and update the records.
(b) In consultation with the Director of Safety, to promote, plan, and conduct a regular programme of safety inspections to ensure that all radiation sources are used in a safe way and stored in a safe cabinet.
(c) To ensure that First Aid and radiation leakage detecting facilities are properly maintained.
(d) To recommend accident prevention measures to the Head as and when necessary.
(e) To provide advice and training concerning radiation safety.
4. The Supervisor of each laboratory/section, teaching and research, has responsibilities for overall safety of all staff members and students in his/her own laboratory/section. The safety duties of the Supervisor are:
(a) To ensure that staff members and students are trained, instructed, supervised, and informed of hazards (and how to overcome them) which they may be confronted with while at work.
(b) To provide and maintain a safe working environment in the laboratory/section including the safe use of equipment and facilities.
(c) To develop and establish safety rules for his/her laboratory/section, if necessary. These rules should be clearly explained to the users of the laboratory (e.g. explained in the introduction lecture, distribute safety notes to students, place posters in laboratory, etc.).
(d) To ensure that staff members and students follow the safety rules and codes of practice that are developed to maintain a high standard of laboratory safety and hygiene.
(e) To report any problem and potential hazards to the Head or the Departmental Safety Representative.
5. Every staff also has his/her own responsibilities not to carry out dangerous acts or omit to take appropriate safety precautions that could result in harm to themselves, their colleagues or any other person. The Department seeks and welcomes the cooperation and assistance of all staff to enable it to fullfil its obligations. Responsibilities of all other appointees and students are:
(a) To make themselves familiar with, and conform to, the safety policies at all times.
(b) To observe all safety rules at all times.
(c) To wear appropriate safety equipment and use appropriate safety devices in accordance with rules and procedures.
(d) To conform to all instructions issued by the appropriate authorities.
(e) To report all accidents and damage of property to their supervisor and the Departmental Safety Representative.
(f) To make appropriate suggestions designed to improve health and safety to their supervisor and the Departmental Safety Representative.
(g) To inform his/her supervisor or the Departmental Safety Representative of any hazards that may be introduced as a result of his/her work.
(h) To be responsible for his/her personal safety.
6. The following members of staff are responsible for safety in particular areas:
|Dr. J.H.C. Lee||Departmental Safety Representative||General Safety Affairs|
|Dr. J.H.C. Lee||Departmental Radiation Safety Representative||Radiation, laser & X-ray Safety|
|Prof. A.B. Djurišić||Fire Warden||Fire Safety|
7. Members of staff are responsible for the safety of all students and minor staff under their supervision.
8. All employees have the responsibility to co-operate with supervisors and staff to achieve a healthy and safe workplace and to take reasonable care of themselves and others.
9. Whenever an employee, supervisor or student notices a health or safety problem, which they are not able to put right, they must straightaway tell the appropriate person named above. They may also tell the Head or the Departmental Safety Representative.
10. The departmental Safety Committee will review regularly the safety policy and the way in which it has operated, and make amendments to, or revisions of, the statement of safety policy as necessary.
|Locations of the first aid boxes||Person responsible for box|
The department office, Rm. 518
|Ms. Joe Poon|
|Surface Science Laboratory, Rm. 416||Mr. Ho Wing Kin|
|Advanced Teaching Laboratory, Rm. 417||Dr. C.C. Ling|
|Radioisotope Laboratory, Rm. 419||Dr. J.K.C. Leung|
|Nanostructure Characterization Laboratory, Rm. 311A||Dr. X.D. Cui|
|Thin Film Laboratory, Rm. 312A||Prof. J. Gao|
|Optoelectronics & Nanomaterial Laboratory, Rm. 314||Dr. A. Ng|
|Physics Laboratory CYP 206, Rm. 206||Mr. Ip Kam Cheong|
|Physics Laboratory CYP 104, Rm. 104||Mr. Lee Chin Ming|
|Semiconductor Physics Laboratory, Rm. G13||Mr. Liu Wing Chuen|
|Laser Spectroscopy Laboratory, Rm. G19||Dr. S.J. Xu|
|Positron Beam Laboratory, Rm. LG208||Mr. Liu Wing Chuen|
|Laser Laboratory, Rm. LG211||Dr. S.J. Xu|
|Nanostructure Synthesis Laboratory, Rm. LG212||Mr. Ho Wing Kin|
|Radon Analysis Laboratory, CP5||Dr. J.K.C. Leung|
Person responsible for reporting accidents: The Supervisor of laboratory/section
Accident record is in (location): The department office (Rm. 518)
GENERAL FIRE SAFETY
Escape route and assembly point:
Yuet Ming Fountain or Pavement at LG3
The following staffs are appointed as Fire Wardens for the specific areas. The duty of a Fire Warden is to check rooms within previously agreed areas to ensure all people have left in the event of fire. He should report any problem (missing persons, non-evacuated staff, dangerous hazards, etc.) to the FSD Fire Officer in charge of the operation directly and without delay. The responsibility also include watching out for and reporting any fire hazards that occur e.g. blockage of fire exits, storage of flammable solvents, damaged fire services installations, etc.
|Prof. A.B. Djurišić||Fire Warden||The whole department|
|Ms Joe Poon||Fire Warden||5/F|
|Mr. Ho Wing Kin||Fire Warden||4/F|
|Mr. Lau Sai Kin||Fire Warden||3/F|
|Mr. Ip Kam Cheong||Fire Warden||2/F|
|Mr. Lee Chin Ming||Fire Warden||1/F|
|Mr. Liu Wing Chuen||Fire Warden||G/F and LG2/F|
The drill for fire/emergency-evacuation will be regularly arranged by the University Safety Office.
Checked annually by Safety Office. More frequently by the technician of each laboratory.
As arranged by Safety Office
Arranged by Safety Office
Person(s) responsible for training:
The Departmental Safety Representative & the Departmental Radiation Safety Representative
The Supervisor of laboratory/section
(Hazardous jobs may need special training)
|Handle radioactive substances & operate irradiating apparatus||Yes|
|Operate lasers (class III and IV)||Yes|
|Fire Warden||Yes (arranged by safety office)|
CONTRACTORS AND VISITORS
Academic staff or supervisors should ensure that contractors maintenance staff and visitors are aware what hazards there are and what precautions they should take. It is the supervisor's responsibility to explain our safety policy to the visitor when they arrive. They must instruct the visitors about potential hazards, safety precautions, the consequences of an accident, the actions to take in case of an accident, fire escape route and assembly point.
WORKING AFTER NORMAL HOURS
Experimental measurements and laboratory are frequently carried out continuously or overnight. It is essential to plan for interruptions in utility services such as electricity, water and inert gas supply. Operations should be designed to be safe, and plans should be made to avoid hazards in case of failure. Experiments involving hazardous procedures should not be undertaken by a worker who is alone in a laboratory.
Students must not be permitted to work alone in a risk area. An undergraduate student who wants to carry out an experiment overnight in a laboratory must obtain the approval from his/her supervisor first. The supervisor must discuss the potential hazards and only if satisfied there is no undue risk, give the student written permission and specify a finishing time. Where permission is granted the students need to be made aware of any rules and regulations that appertain to the laboratory, studio, or workshop. These rules need to be written down and adequately communicated by briefing. The student should sign a receipt indicating he understands the requirements and will abide by them.
See Code of Practice: 'Work Outside Normal Working Hours'.
All accidents are reported on the Accident Report form, which is available in the departmental office (Rm. 518). All columns of the report form should as far as possible be completed on the same day as the accident. The Supervisor will make a report to the Head of department, the Departmental Safety Representative, and/or Clinic as appropriate.
STORAGE OF CHEMICALS
The department only keeps small quantities of a limited number of chemicals. The quantities involved do not fall within the scope of the Dangerous Goods Ordinance. The chemicals must be stored in lockable wooden cabinets with chemically resistant trays. All chemicals are kept in labelled containers and are recorded in the Chemical List. Regular routines and inspections ensure that chemicals are properly stored and obsolete chemicals are disposed of.
STORAGE OF RADIOACTIVE SUBSTANCES
The department only keeps small quantities of radioactive sources, which are required by the teaching and research purposes. The radioactive sources must be stored in lockable lead boxes. The key is under control of the Supervisor of the laboratory. These boxes will be regularly checked by using radiation detectors for radiation leakage and contamination. All radioactive sources are registered by the Departmental Radiation Safety Representative.
USE OF SAFETY GOGGLES
Safety goggles must be worn when using lasers of class III and class IV. Every class III and class IV laser must be equipped with safely goggles which are designed for the particular wavelength and power level.
ADVICE AND CONSULTANCY
Departmental Safety Representative: Dr. J.H.C. Lee, tel. - 2219 4616
Director of Safety: tel. - 2859 2400
University Health Service:
tel. - 3917 1999 (Emergency during office hours), 2549 4686 (Medical Appointment)
Campus Security: tel. - 3917 2882 (24-hour)
The main hazards encountered in the Department of Physics are electric shock when using high voltage instruments, radiation hazards from radioactive substances, radiation producing machines, and powerful lasers, chemical hazards from using chemicals, compressed gases, cryogenic gases, toxic materials, and machinery. It is therefore the department's commitment to minimise the above hazards by every effort. Following the safety rules and Codes of Practice will greatly reduce the risk.
Academic staff and technicians of the teaching and research laboratories are responsible to keep their electric equipment safe and to arrange for regular thorough checks on their electrical equipment. They should often inspect earth connections, plugs, and cables for loose connections and faults. The plugs used in the laboratory should comply with British Standard 1363 or 546. All high voltage instruments must be well connected to the dead earth.
Detailed regulations: see the Safety Booklet.
The dangerous or toxic substances, like As, Hg, Ga, K, Na, Pb, T1, etc., used in teaching and research laboratories/section must be stored in lockable cabinets. The key must be under control of the Supervisor of laboratory/section. The Supervisor must ensure that the staff and students under his/her supervision clearly understand and follow the safety rules and emergency procedures. All measures for safety and emergency actions must be regularly checked.
COMPRESSED GASES, PRESSURE & VACUUM PROCEDURES
Academic staff and technicians are responsible for the safety of using compressed gas in their laboratory. In case of fire, the staff and Fire Warden should report to the FSD Fire Officer the location of the gas cylinders and the kind of gas contained in the cylinders.
Compressed gas cylinders used in the laboratories contain a tremendous amount of energy, which can be violently released under certain conditions. The flammable and/or toxic nature of some of the gases could pose a serious potential hazard if accidentally released. Compliance with the following guidelines can greatly reduce these risks.
- Each cylinder must bear a label identifying its contents. Make sure you know the contents and characteristics of the gas before use.
- Use gases in areas having adequate ventilation.
- Cylinders should be moved only with a suitable trolley, never rolled or dragged.
- Cylinders must not be transported with the regulator attached.
- In the laboratory cylinders must be strapped to the wall, bench top or other firm support. Cylinders should not be subjected to temperature over 50 oC or a direct flame.
- Cylinders containing oxygen should be kept away from flammable gases or large quantities of flammable liquids.
- Use proper tools to tighten the regulator and to open the cylinder main valve.
- Check leakage of all joints after the completion of the connection, using soapy water.
- Never tamper with safety devices in cylinder, regulator or valve. The cylinder main valve should be shut off when it is not in use.
- If the gas is corrosive, the cylinder main valve shall be worked frequently to prevent it from corroding and sticking. Regulator and valves shall be removed and flushed with dry air or nitrogen after use, not just left on the cylinder.
- The date required for pressure test of the cylinder shall be noted for all privately owned cylinders as they are required by law to be pressure tested at regular intervals.
For vacuum systems, every operator should carefully read the manufacturer's guidance and instructions or consult his/her supervisor before operating the vacuum system.
The primary hazard from laser radiation is exposure of the eye and to a lesser extent, the skin (particularly with a high power UV laser). As lasers are widely used for a variety of purposes in our teaching and research, great precaution is taken for the laser safety.
The Departmental Radiation Safety Representative should register all laser equipment in the department and all persons using the laser equipment. Caution warning labels and tags should be placed prominently on the laser housing and control panel. Measures to minimise laser hazards include:
- Classes III and IV lasers should be used in a designated laser area, conspicuous signs and warning light indicating that laser is in operation and that it could be dangerous should be prominently placed both inside and outside the work area, and on doors providing access to the area. Doors should be locked during laser' usage.
- Only authorized persons can operate the laser equipment and the laser should not be left running unattended.
- Always work with the maximum room lighting (minimum pupil).
- Remove watches, rings, bracelets and other shiny jewellery while working in the designated area.
- Never look directly along a laser beam or at reflections caused by a laser.
- Safety eyewear designed to filter out the specified laser should be worn whenever risk of exposure to hazardous levels exists.
- Good housekeeping practices should be used to ensure that no specular objects are discarded in the laser beam path.
- All electrical connections should be adequate with proper earthing.
- Always report any accidental exposure as soon as possible.
See the Code of Practice: 'Protection Against Laser Radiation in Laboratory'.
Cryogenic gases could result in a deep freeze, and could produce excessive pressures when stored in a closed container. It could expand quickly if heated. Precautions should be taken when handling cryogenic gases. To safely use cryogenic gases, one should:
- Avoid contact with both the liquid and the gases as they can cause frostbite. Do not touch uninsulated piping.
- Wear loose-fitting thermal gloves, goggles and/or face shield and closed shoes.
- Work in a well ventilated area. Liquefied gas vaporizes and expands rapidly, e.g. nitrogen expands almost 700-fold.
- Never attempt to prevent vapours from escaping from cylinders of liquefied, cryogenic gases. Since they are not in thermal equilibrium, vapour is produced as the liquid boils and, if not vented to the atmosphere, could produce excessive pressure.
- Use only the special (usually metal) tubing designed for use with these gases. Do not improvise with plastic or rubber tubing.
- Be aware that oxygen enrichment and a fire hazard can result from the condensation of oxygen (boiling point -183 oC) from the air onto piping cooled by liquid nitrogen (boiling point -196 oC).
- If a glass dewar flask is used as container of small quantities of liquid nitrogen, the exposed glass part of the flask should be taped to minimize the flying glass hazards in case of implosion or explosion.
- If a domestic thermos flask is used as container of small quantities of liquid nitrogen, the integrity of the plastic sealing ring of the thermos should be checked regularly to ensure that no liquid nitrogen can get into the space between the thermos and the outside container. In every case ensure holes are drilled in the base plate to allow gas to escape.
- Avoid contact with the liquid nitrogen directly. Always wear gloves (leather or CRYO-GLOVES) when handling anything that is in contact with liquid nitrogen.
- Protect your eyes with safety spectacles with side shields, safety goggles or face shield. Eyes can be damaged even by the cold gas issuing from liquid nitrogen.
- When charging a warm container or when inserting objects into the liquid, perform the operation slowly to minimize boiling and splashing.
If skin contacts liquefied cryogenic gases, thaw burned area slowly in cold water. Do not rub.
Academic staff, student supervisors, and laboratory technicians are responsible for establishing safe procedures and providing the protective equipment needed in handling chemicals. They must instruct their personnel about potential hazards, safety precautions, waste handling, the consequences of an accident, and the actions to take in case of an accident. It is also their responsibility to ensure all chemicals are labelled adequately.
Bulk quantities of dangerous goods (DG) should be and are stored in Central D.G. Stores managed by the University Safety Office.
General requirements for keeping small quantities of chemicals in laboratories are as follows:
- Provide fresh air ventilation.
- Clearly label the storage area and each container. Container labels must give the chemical name, type of hazard, special precautions, and emergency information where space permits. Labels are available from the Safety Office.
- Store heavier items on lower shelves.
- Chemicals, particularly those known to decompose with time, should also be marked with the date of receipt.
- Carcinogens and highly toxic chemicals should be stored in double containment.
- Separate incompatible chemicals by physical barriers. For example, the following classes of chemicals are mutually incompatible: acids, bases, oxidizers, pyrophoric, flammables, toxic, and water reactive.
- Provide a means to contain spills (e.g. trays).
- Limit quantities and observe shelf-life limits.
- Only flameproof refrigerators or those where all electrical contacts (thermostats, lights etc.) are moved externally are suitable for storage of flammable liquids. The storage of volatile, flammable liquids in ordinary refrigerators can lead to and has led to serious explosions.
Handling solid and liquid chemicals
- Keep the work area clean and orderly.
- Do not eat, drink, smoke, apply cosmetics, or store food in the work area. Read all container labels and, if necessary, the MSDS'S.
- Use required safety equipment. The minimum protective clothing is a laboratory coat and safety glasses; for additional protection, wear gloves and a face shield.
- All works should be carried out in an efficient fume cupboard or at least in well ventilated rooms.
- Wipe off splashes on the skin first by a dry cloth, then immediately with plenty of cold water followed by washing with hot water and soap. Never use organic solvents because of the risk of adsorption.
- Thoroughly rinse eyes affected by chemicals with water and immediately afterward take the patients to a medical centre. Inform medical personnel of the chemical involved.
- Immediately remove any items of clothing soaked with corrosive substances.
- Wash your hands regularly when working with chemicals, especially before you leave the laboratory.
- Breakable vessels must not be carried by the neck and must be supported from below. They must be transported in baskets or carrying frames over longer distances such as up and down stairs, or along corridors.
There is a high fire risk in many laboratories because of the storage and handling of flammable liquids. It is, therefore, essential that the means of escape from the workplace are not obstructed.
The following precautions should be observed:
- Do not use an open flame to heat a flammable liquid.
- Use an open flame only when necessary and extinguish it when it is no longer actually needed.
- Before lighting a flame, remove all flammable substances from the immediate area. Check all containers of flammable materials in the are to ensure that they are tightly closed. Tell your colleagues that you intend to use naked flames.
- Quantities of flammable substances in laboratories should be kept to a minimum. The maximum storage is 20 L of any one substance but not more than 40 L in aggregate. When not in use solvents should be kept in suitable fire resistant cabinets.
- Empty containers which have held flammable materials will contain explosive quantities of vapour if the container is not washed out or ventilated.
Highly reactive chemicals and unstable chemicals
Some chemicals react in combinations with others at ordinary temperatures, sometimes with great violence. This reactivity may be manifested as a corrosive effect, or as the liberation of a large amount of heat or even an explosion when the chemical comes into contact with others or is exposed to moisture or air. For example:
- Powerful oxidising agents such as perchloric acid, nitric acid or chlorine react violently with easily oxidisable materials such as hydrocarbons.
- Metal alkyls such as triethylaluminium burst into flames on exposure to air.
- The alkali metals react vigorously with water.
Although not themselves explosive, some compounds can cause their containers to burst because of the high pressure of gas generated in them through, e.g. hydrolysis, or decomposition, chlorides of aluminium, titanium and silicon, formic acid.
Some chemicals can explode if heated or subjected to mechanical shock, like metal acetylides, azides, azo and diazo compounds, chlorates and perchlorates, highly nitrated organic compounds, nitrogen halides, organic peroxides, and organic salts of per-acids.
Peroxidisable chemicals, when in the presence of oxygen and stored for long periods of time, or when exposed to sunlight, can form unstable peroxides. These peroxides may explode if the container is shaken or heated. Examples of peroxidizable materials are diethyl ether, tetrahydrofuran, dioxan, alkali metals, olefins, and vinyl monomers. The precautions are:
- Stored in dark containers away from direct sunlight; in a storage cabinet for flammable liquids.
- The date of opening should be marked on the bottle.
- Chemicals should be tested for the presence of peroxide regularly and always prior to use.
Some chemicals which have explosive properties when dry need to be kept wet or moist for safe storage: e.g.
4-Fluoro-3-nitrophenylhydrazine Hexanitrodiphenylamine Picric acid
For these chemicals, the following safety procedures should be taken:
- Inspect containers regularly and add water as necessary.
- When the contents have gone completely dry, immerse the container in water, with a small amount of detergent, for at least 24 hours.
- With the container still under water, slowly unscrew the cover, allowing water to wet the screw threads.
- Once the closure is loose, remove the container from the water bath, remove the cover and add the required amount of water.
Emergency response for chemical spill
Small spills can usually be cleaned up safely by the employees involved. Employees must be trained to handle cleanup of small spills. Material for clean up of common chemical spills are available from the Safety Office. Keep used material in a waste container.
If a spill involving large amounts of hazardous chemicals occurs:
1. Alert your fellow workers immediately.
2. Confine spill if safe to do so.
3. Open the windows and switch on the fume cupboard to ventilate the area.
- turn off all burners;
- switch off all electrical equipment which have hot surfaces, (e.g. hot plate) or/and generate electric spark (e.g. brush type motor) NOT in vincity to the spill and
- do NOT switch on/off or unplug any electrical equipment.
4. Call nearby Fire Brigade, Security Guard and Safety Office.
5. If your clothes are contaminated, remove them immediately.
6. Evacuate the room. Make sure no body stays behind. Close the door(s) of the laboratory after you leave.
7. Keep distances from the laboratory but with the entrance in sight, forbid unauthorized entry to the laboratory and wait for the arrival of the fire brigade.
The arrangement of chemical waste
See the code of practice: 'The Arrangement of Chemical Waste'.
See the Code of Practice: 'Guidelines For Chemical Safety In Laboratory', and 'Guidelines For Chemical Labelling'.
See the regulations issued by the Labour Department: 'Handbook on Guarding and Operation of Machinery'.
It is required by law that any person working in controlled/supervised radiation areas or working with irradiating apparatus in University premises be designated either as a radiation user or radiation worker. A radiation user/worker has the responsibility of ensuring that radiation exposure to all persons, including oneself, is kept as low as reasonably achievable and in any case below the stipulated dose limits.
All radioactive substances and irradiating apparatus in the department should be registered by the Departmental Radiation Safety Representative. The Departmental Radiation Safety Representative will regularly inspect the controlled/supervised radiation areas and arrange for appropriate protective measures to be implemented.
Each controlled area is required to install and operate an appropriate radiation monitor for the work performed therein. Additionally, air-sampling and surface monitoring will be carried out by staff of the Safety Office.
Radiation work and pregnancy
The radiation dose limits prescribed for designated radiation workers are not applicable during pregnancy, particularly during the early stages.
Therefore, radiation users/workers who know or suspect that they have become pregnant, must report immediately to a doctor in the University Health Clinic so that advice may be given and the necessary action taken.
Use of thermoluminescent dosemeter (TLD)
The TLD must be worn when working inside controlled/supervised radiation areas. The dosemeter should be worn on that part of the body expected to be exposed to the highest radiation dose. For certain purposes, supplementary wrist or finger dosemeters may be required. When not in use for monitoring purposes, the TLD should not be left inside the controlled/supervised radiation areas unattended.
An outline of recommended procedures to be followed when receiving packages of radioactive materials.
- It is recommended that, as a matter of routine, rubber or plastic gloves be worn whilst processing the package.
- Monitor the outside of the package to determine the radiation field (hard betas/gammas) or possible contamination (soft betas).
- Install suitable shielding around the package (hard betas/gammas).
- Check for possible breakages or cracks in the vial; perform wipe tests as necessary.
- Record nuclide, chemical composition, activity and date of receipt in register. Ensure container is properly labelled.
- If material is not to be used immediately, place in safety container and store in a shielded safe or refrigerator as appropriate.
Radioactive waste disposal
All radioactive wastes should be collected in approved and labelled containers. A waste collection service is available from the Safety Office. It is the responsibility of the user to keep proper records of the nature and content of the waste material in each container and to inform the Safety Office when collection is required. Appropriate forms may be obtained through the web (http://www.hku.hk/local/radioiso/rpframe.htm). Radioactive waste MUST NOT be discharged into sewers or normal rubbish bins.
Procedures to minimise radiation hazards
Initial design of experiment
- All operations should be planned to limit the spread or dispersal of radioactive material. To this end all unnecessary movement of persons or materials should be avoided.
- Planning should allow adequate time for the operations required.
- The use of new techniques should first be tried out with inactive materials or with material of low activity before being put into operation.
- Areas in which radioactive work is carried out should be designated, marked and monitored. At the boundaries of such areas, monitoring and control measures should be set up if so required by the levels present.
- Equipment, glassware, tools and cleaning equipment for use in any particular active area should not be used for work in inactive areas and should be suitably marked. Special consideration should be given to avoiding contamination of major items of equipment which might need to be transferred for economic reasons.
- When a choice between several isotopes of varying toxicities is possible, one of relatively low toxicity should be used.
- Materials of low specific activity should be used if possible.
- The quantity of radioactive substances chosen as necessary for a specific purpose should always be as small as possible.
- The working methods should be studied and procedures adopted to avoid as far as possible the dispersal of radioactive material, in particular through the formation of aerosols, gases, vapours or dusts.
Working procedures (general)
Laboratory rules must be observed absolutely and these will normally include an appropriate selection from the following:
1. The following should not be introduced or used in working places containing unsealed sources:
- Food or beverages.
- Smoking items or snuff tobacco.
- Lipsticks and other cosmetics, or items used to apply them.
- Utensils for eating or drinking.
2. Hands should be washed thoroughly before leaving the controlled area (special attention should be given to the nails, in between fingers and outer edges of the hands).
3. Monitoring of hands, shoes and street clothing, if worn at work, may also be necessary before leaving the controlled areas.
4. No sealed or unsealed radioactive sources should be manipulated with the hands.
5. All radioactive sources should be handled with equipment and facilities providing protection against external radiation to compile with the following limits:
- inside controlled areas: less than 0.01 mSv/h
- inside supervised areas: less than 0.003 mSv/h
- in general public areas: less than 0.0001 mSv/h
6. Manipulations should be carried out over a suitable drip tray, or with some form of double container which will minimize the importance of breakages or spills. It is also useful to cover the working surfaces with absorbent material to soak up minor spills. The absorbent material should be changed when unsuitable for further work and be treated as radioactive waste. The handling tools and equipment used should be placed in nonporous trays with absorbent disposable paper, which should be changed frequently. Pipettes, stirring rods and similar equipment should never be placed directly on the bench or table. After use, all vessels and tools should be set aside for special attention when cleaning.
7. No solution should be pipetted by mouth in any isotope laboratory.
8. Anyone who has an open skin wound below the wrist (protected by a bandage or not) should not work with radioactive isotopes without medical approval.
9. The use of containers, glassware, etc., with cutting edges should be avoided.
10. Glass-blowing by mouth should be avoided in places where unsealed radioactive substances are utilized.
11. Only self-adhesive labels should be used in controlled areas. Labels that must be wetted should be avoided.
12. Protective clothing appropriate to the radioactive contamination risks should be worn by every person in the controlled area, even if only very small quantities of radioactive materials are manipulated.
13. Rubber gloves should be worn when working with unsealed radioactive substances. Rubber gloves are provided to protect against contamination of the skin and are of no value for protection from penetrating radiation.
14. Care should be taken to avoid needless contamination of objects by handling them with protective gloves, in particular light switches, taps, door knobs, etc. The gloves should be either taken off or a piece of non-contaminated material (paper), which should be disposed of afterwards with the contaminated residue, should be interposed.
15. Contaminated gloves should be washed before taking them off.
16. A method of putting on and removing rubber gloves without contaminating the inside of the gloves should be used. This procedure is such that the inside of the glove is not touched by the outside, nor is any part of the outside allowed to come in contact with the bare skin. It is desirable to use gloves for which the inside and outside are distinguishable.
17. Radioactive contamination of the air of the working places should be reduced as much as possible. All operations likely to produce radioactive contamination of the air through the production of aerosols (in particular the heating of radioactive solutions), smoke or vapours should be done in an air-tight enclosure kept below atmospheric pressure (glove box) or in a fume hood.
18. Wet operations should be used in preference to dry ones.
19. Frequent transfers should be avoided.
20. Clean up spills immediately to prevent contamination of the atmosphere through dusting.
For work with animals one must also pay attention to:
21. Excrete, body constituents from biopsies and autopsies and animal cadavers should be treated as radioactive wastes. Possible hazards of spread of contamination through the decomposition process should be prevented, e.g. by deep freezing, use of disinfectants, sealed plastic containers, etc.
22. Special provisions for the collection of excreta and decontamination of cages should be made.
23. The radioactive animals or their cages should be marked with labels indicating the nature and amount of radioisotopes used and the time of administration.
24. No uncontrolled exchange of animals, instruments, cages, etc., between active and inactive laboratories should be allowed.
25. Precautions should be taken to prevent the possibility of contaminated wounds in the course of handling the animals and of contamination from radioactive aerosols or splashings produced by animal's movements, coughing, etc.
26. The presence of vermin as potential vectors of contamination should be considered.
1. All radioactive sources must be clearly labelled giving information on activity, date and chemical form.
2. The place of storage should be adequately shielded.
3. Only authorized personnel should be allowed to introduce or remove sources into or from the place of storage, which should be secure against tampering.
4. The place of storage should be chosen so as to minimize risk from fire.
5. The places where sources are stored should be inspected regularly and checked for possible contamination.
6. When either sealed or unsealed sources are liable to release a radioactive gas, their place of storage should be efficiently vented to the open air by mechanical means before it is opened.
7. Records should be kept of all stored radioactive sources.
8. Bottles containing radioactive liquids should be placed in vessels large enough to hold the entire contents of the bottles in case of breakage.
9. Special precautions are required when opening vessels containing radioactive liquids liable to catch fire, explode or froth.
Any unplanned happening which may introduce a radiation hazard is considered to be an ACCIDENT or an EMERGENCY. Such happenings may arise from a wide variety of causes ranging from a simple spill of radioactive material to a natural disaster such as flood or earthquake.
1. Priority must be given to human safety according to need and urgency.
2. A serious fire hazard must take precedence over a contamination hazard.
3. Warn all other persons in the vicinity by the most appropriate means. Inform the Departmental Radiation Safety Representative or the Director of Safety as soon as possible.
4. In the case of a spill of radioactive material, without other complications, primary consideration must be given to containment of contamination. The extent of contamination should be determined and the area clearly marked.
5. Persons directly contaminated by a wet spill should immediately remove clothing affected and thoroughly wash the hands and other contaminated areas of the body.
6. If an inhalation hazard exists, all persons not involved in carrying out planned safety procedures should vacate the contaminated area immediately.
7. If evacuation of the room is required, it will generally be desirable to shut off all mechanical ventilation and to close all outside openings. However, there may be local conditions which require consideration. For example, if the release occurs in or near a fume hood, it may be disadvantageous to take any action which would discontinue ventilation by the hood.
8. Except in case of injury or other urgent need, persons who have vacated the contaminated area should not leave the immediate vicinity until they have been monitored and necessary precautions, such as the removal of shoes or outer clothing, have been taken to limit further spread of radioactivity.
9. Re-entry into the affected area must be restricted to properly equipped persons until the area is declared safe by the Director of Safety.
10. All accidents should be fully reported. This report may have an important bearing on staff health and legal responsibilities and may assist the Director of Safety in making a detailed study with a view to avoiding similar accidents in the future.
11. All accidents should be investigated and appropriate measures should be taken to prevent repetition of the accident.
For further details about radiation protection services, please visit the Safety Office website at http://www.hku.hk/safety/.