The Department of Chemistry requires that when researchers leave, all chemicals or other potentially hazardous material or equipment, not to accompany them, be disposed of properly by them.
Head of Department will not allow Theses to be processed to viva without a completed and fully signed copy of the Clearance Form.
In normal operation, radioactive materials are carefully recorded and disposed of regularly. Carefully label and make secure any remaining material e.g. stock vials, sealed sources etc. Ensure that each item has an associated Stock Card. If it does not, start one.
If samples are to be saved then responsibility for them can be transferred to another person who is willing to accept the responsibility and who has indicated such willingness in writing. If no such person can be found, dispose of the material in the proper way. Record such transfers and disposals on the appropriate Stock Card.
Check for contamination and if necessary decontaminate, clean and tidy up the work area. Where significant activities have been held and used and the laboratory is to revert to non-radioactive use, OSHE must confirm in writing that the laboratory has been adequately cleared and decontaminated.
Complete the Clearance Check List including the appropriate signatures.
Inform your Research Supervisor when the laboratory has been cleared and record his/her approval.
Only radioactive waste that have been left to decay to negligible proportions as required by Centre of Radiation Protection of Health Sciences Authority (CRP,HSA) in its licenses to various Departments are allowed to be disposed of by landfill or controlled discharge into sewer. All other radioactive waste must be kept in designated secured waste storage areas or returned to original suppliers.
Only radiation Workers who have been licensed to be engaged in radiation work are allowed to handle radioactive waste resulting from radioactive materials they have used. They are to ensure proper control, safe packaging and identification of the waste before the waste are packed into containers for safe handling by non-radiation workers.
All dry wastes must be deposited into red plastic waste disposal bags with NUS logo and radioactivity hazard symbol. Each disposal bag should contain waste only contaminated with a single radionuclide and should not have radioactivity quantities exceeding one Licensing Exemption Limit (LEL) given in the First Schedule to the Radiation Protection Regulations, 1974. The Licensing Exemption Limits for commonly used radionuclides are:
| Radionuclide | Licensing Exemption Limit (in µCi) |
| Carbon 14 | 100 |
| Hydrogen 3 | 1000 |
| Iodine 125 | 10 |
| Phosphorus 32 | 10 |
| Sulphur 35 | 10 |
(b) Waste contaminated with more than one radionuclide must satisfy the following condition before it can be accepted for disposal: (A1/M1 + A2/M2 + A3/M3 ≤ LEL of the most active nuclide) where A1, A2, A3, etc. are the quantities of the radionuclides involved and M1, M2, M3, etc. are the licensing exemption limit for each of the radionuclides.
(c) Each bag when full shall be closed and securely sealed with masking tape. The activity, content and isotope shall be entered on the waste disposal form (Form RAD01-1) and on the radioactive waste container label (yellow form) which is to be adhered on to the waste disposal bag. The exposure rate on the surface of each bag must not be greater than 0.1 mRem/hr (1 µSv/hr).
(d) Glassware and sharps such as vials and syringes are to be packed separately in bins or multiple layers of bags suitably padded before they are placed in cartons. Animal carcasses for disposal should be refrigerated and/or chemically preserved. They are subject to the same disposal criteria as dry solid waste and to be packed in separate containers. All container surfaces are to be free from radioactive contamination. (e) All bags must be packed and deposited at secured area in the Department. They are to be checked by the NUS safety officers and inspectors of the Centre of Radiation Protection and the Pollution Control Department before they are certified safe for disposal. No compaction of radioactive waste is permitted.
Contaminated solvents should be solidified by absorption into vermiculite (an absorbent material) at point of use and disposed of as dry solid radioactive waste.
(a) Rinse water from 3rd and subsequent rinsings of apparatus should be discharged into the sewer directly at point of use.
(b) First and 2nd rinsings and other aqueous waste should be collected in containers and disposed of centrally to the sewer, making use of storage and dilution to render it safe. Aqueous wastes are to be transferred first to one gallon reagent bottles or other approved containers. Full bottles are to be capped with moulded resin screw caps and the caps sealed.
(c) No aqueous and solvent type radioactive waste are to be mixed in the same container. Whenever possible each container should contain waste only contaminated with a single radionuclide.
(d) The activity, isotopes, type of liquid and quantity shall be entered on the waste disposal form (Form RAD01-1) and on the radioactive waste container label (yellow form). The containers should be delivered to designated secured waste area within the Department for storage and checking prior to dilution and controlled discharge into the sewer. The waste disposal form must be certified safe for disposal by the Safety Office and relevant authorities before the waste is discharged into the sewer.
(e) All aqueous waste must be neutralized to a pH of approximately 7.0. The level of radioactivity allowed in the sewer should be controlled to 1/10 the Maximum Allowable Concentration (MAC) as shown in 3rd Schedule to Radiation Protection Regulations, 1974. The period of storage and the amountof water used for dilution should be sufficient to ensure that: (Radioactivity after decay/Total amount of water used ) ≤ 0.1 MAC for the combination of radionuclides.
Complete the REQUEST FOR DISPOSAL OF RADIOACTIVE WASTE form.
For clearance of the entire laboratory, apply all of the appropriate procedures.
Arrange for a handover inspection with the Safety Committee and/or FOS Safety Officer before leaving. Fill up OSHE’s Lab Decommissioning & Verification Form beforehand.
Bring the completed Lab Decommissioning & Verification Form to the handover inspection. Upon completion of the verification exercise, a confirmation email will be sent to the Head of Department, and cc to PI.