14. Waste disposal
Contents
14.1.1 Disposal via a Macerator
14.1.2 Disposal to Landfill Sites
14.1.3 Disposal to Specialist Contractor
14.2 Liquid Waste (Water Soluble)
14.3 Liquid Waste (Organic Solvents)
14 Waste Disposal
The prime purpose of the Radioactive Substances Act 1993 is to ensure that members of the general public are not affected by the deliberate or accidental discharge, or disposal, of radioactive material or waste. To achieve this end, all users of radioactive materials are required to:-
- obtain a Registration Certificate or certificates from SEPA for the radioactive materials which they have, or intend to have, on the premises; and
- obtain a waste disposal Certificate of Authorisation from SEPA which details the conditions which must be observed for the disposal of radioactive waste.
The University, through the Radiation Protection Service, applies for, and obtains, such documents from SEPA. In general, they are issued for individual buildings. The documents which relate to a particular Building, together with any allocations made by a School/Unit, are posted in the buildings concerned, and persons working there must familiarise themselves with all relevant details. The maintenance of records to demonstrate compliance with the terms of the Certificates of Registration and Authorisation is required, and special forms are provided for this purpose (see Appendices 27 and 28). Anyone in any doubt as to what is required should consult his/her DRPS or URPA.
14.1 Solid Waste
Up to three methods are available for the disposal of solid waste, and it is important that you use the one appropriate to your work -
- Disposal to a drain by a specified macerator unit.
- Disposal to landfill sites
- Disposal via a specialist contractor.
A record of all solid waste should be kept using the form URPS 5 (see Appendix 30). A written record of the transport of radioactive waste should be kept on the form in Appendix 31.
14.1.1 Disposal via a Macerator
Animal carcasses and animal waste, plants (but not soil) may be disposed of using a macerator unit which has a SEPA Authorisation Certificate. It is important that the operating instructions posted by each unit be observed, and also that activities are controlled so that the quantities permitted for the disposal of active liquid waste in the authorisation issued by SEPA are not exceeded. In this context it is important to remember that other people will be using the system too and if there is any doubt about the total discharge exceeding permitted values, the URPA must be contacted. Entries must be made in the record books located by each macerator for each disposal which is made.
NOTE: Remember when recording waste in your own records to record macerated waste as aqueous and not solid.
14.1.2 Disposal to Landfill sites
Low level radioactive contaminated waste produced by Schools/Units is disposed of at a SEPA Registered landfill site. All containers of waste must be correctly labelled with details of School/Unit, radionuclides and approximate activities clearly marked.
The waste will be collected from School/Units by the Radiation Protection Service and kept in a SEPA Registered University store. When a suitable quantity has been accumulated, it will be transported to the landfill site.
14.1.3 Disposal using Specialist Contractor
Material, which by virtue of its total activity or special toxicity cannot be disposed of by one of the above, must be disposed of via a specialist contractor. All containers of waste must be correctly labelled with details of School/Unit, radionuclides and approximate activities clearly marked.
The School/Unit producing such waste should contact the Radiation Protection Service who will make the necessary arrangements for transport and disposal.
14.2 Liquid Waste (Water Soluble)
Only those sinks or sluices specially designated by the URPA for the purpose and appropriately identified, may be used for the disposal of liquid waste (see Appendix 26). Non-designated sinks must NOT be used under any circumstances.
NOTE: The quantity of liquid waste disposed of to drain in a Building must never exceed the limits set by SEPA in the Authorisation Certificate.
Where practicable all liquid wastes must be diluted with the appropriate carrier before disposal. In many instances this may just be water, but some compounds tend to stick to the surface of the drains, and in this case you will need to use a carrier which will help to take up the available sticking sites so that you are not left with a 'hot' sink or sluice.
Sinks should be rinsed before and immediately after the discharge, and sluices must be flushed at least three times - once before and twice after. For all materials other than tritium, the sink or sluice must be monitored after disposal, and any residual activity removed if reasonably practicable.
A written record of all disposal to drain should be kept by the designated sink by using form URPS 6 (see Appendix 32).
14.3 Liquid Waste (Organic Solvents)
This mainly concerns the disposal of scintillant waste in counting vials. On no account must organic solvents be flushed down a sluice or the drain. All such waste should be stored in appropriate containers e.g. vials with scintillant present should be stored in appropriate plastic drums. The contents of the container should be described in terms of the radionuclide(s) present, the total activity in it and the date.
The producer of radioactive liquid organic waste should contact Radiation Protection Service who will collect this waste and put it into a SEPA Registered store. The waste will then be disposed of by a 'Specialist Contractor'.
Collection of bulk radioactive solvent waste is on an irregular basis and anyone needing collection should make arrangements with Radiation Protection Service at the time.
14.4 Gaseous Waste
Any operation that is likely to produce radioactive gas, vapour or dust, must be carried out under a ratified Radiation Project and in an approved fume cupboard. In certain special cases involving powders glove boxes may be required and the advice of URPA should be sought.
NOTE: In the above circumstances, the quantity of gaseous waste disposed via a fume cupboard in a Building must never exceed the limits set by SEPA in the Authorisation Certificate.
The fume cupboard must always be operated with an air-flow sufficiently great to ensure the contents cannot leak back into the laboratory - normally a minimum of 0.5 m/s across the face opening is required. The sash must always be kept clear so that it can be closed in the event of an emergency.
The point at which effluent air is discharged must be sited to prevent, as far as it is practicable, its entry into any part of any premises by way of windows, air-intakes etc. In certain cases, filters may be necessary. Radiation Protection Services will advise accordingly.
It should be noted that radioactive gas or fumes might sometimes be generated unwittingly. For instance the tritium sources used in vapour phase chromatography units will release tritium if over-heated, and the outlets from such units must always be vented to the outside atmosphere rather than into the laboratory. Similarly it is not unknown for some stock materials to undergo radiation decomposition with the release of fumes. Stores where such materials are held must be suitably ventilated.
NB. Vials containing any isotope that could release volatile compounds during storage should be vented in a fume cupboard before use on the open bench can be considered. This affects the use of H-3, C-14, S-35 and I-125 labelled material.
Note: The law requires the maintenance of suitable records for the discharge of any form of radioactive waste. Each and every user must ensure that such records are properly kept. Failure to do so, or to comply with the other requirements of the Radioactive Substances Act 1993, could result in prosecution with penalties of fines and imprisonment.