School of Physics Safety Manual

10. IONISING RADIATION REGULATIONS AND PROCEDURES

Introduction

All persons wishing to work with ionising radiations for the first time must contact the School Radiation Protection Officer who will arrange for registration with the University Radiation Protection Officer.

Since January 2000 the University has been subject to the Ionising Radiation Regulations (1999) made under the Health and Safety at Work Act (1974), which protect individuals from injury at their place of work. Anyone working with radioactive substances (or equipment that produces ionising radiations) is subject to these regulations. The Health and Safety Executive (HSE) administers and checks compliance with the regulations. A copy of the relevant guidance notes and procedures is available at the documents page of the Health and Safety office website.

Radiation protection is based on three general principles:

·         practices exposing individuals to ionising radiation must be justified by the advantages produced;

·         exposures must be kept as low as reasonably achievable;

·         the sum of doses received shall not exceed certain limits.

The University is also subject to the “Radioactive Substances Act” 1961 and 1994, which controls holdings of radioactive materials and their disposal.

Organisation

The University appoints both as Radiation Protection Adviser (RPA) (currently an external consultant) and a University Radiation Protection Officer (URPO). The function of the RPA is to advise the University, whereas the URPO is responsible for most of the day-to-day running of the University Radiation Protection Service. Part of the responsibilities of the SRPO are to:

• keep an inventory of radioactive materials stored throughout the University site, and to make returns as required by the Enforcing Authorities
• organise and control the correct disposal of radioactive waste
• leak-test sealed sources held within the University every two years.
• order and distribute all new radioactive material required by authorised users
• assess the need for personal dose monitoring of individual workers, organise the procurement and distribution of relevant dosemeters, maintain dose records for non-classified workers and to forward those for classified workers to the National Radiological Protection Board
• investigate and account for abnormal dose returns and to keep a record of all incidents and accidents involving ionising radiations.

The School Radiation Protection Officer (SRPO) oversees all matters concerned with radiation protection within the School and liaises with both the University Radiation Protection Officer and with specific Radiation Protection Supervisors (RPS) within the School who are responsible for proper supervision in specific laboratories/areas. The SRPO is to:

• ensure that the Local Rules, schemes of work and Regulations are adhered to
• ensure that suitable and appropriate training is provided for all radiation workers
• keep the URPO informed of all changes in the nature of the work in the School, and to assist in the reformulation of Local Rules and schemes of work to accommodate these
• ensure proper keeping of records for radioactive materials brought into the School, their usage and disposals
• ensure that all disposals are in accordance with the waste disposal certificates held by the University
• make regular checks and inspections of storage sites for radioactive materials and to monitor radiation levels at these sites, to monitor contamination of working surfaces etc. at least two times each year and to keep records of these checks
• monitor the scatter and leakage from any X-ray analytical equipment at least twice a year and to keep records of these measurements
• report to the URPO any irregularity noted during the above checks, or arising at other times
• arrange with the URPO for the disposal of waste
• inform the URPO of new workers in the School so that medical tests can be arranged for them if necessary and so that they can be interviewed by the URPO, and to inform the URPO when any worker ceases to work with ionising radiations or leaves the University
• organise, where necessary, free access to areas of the School by the URPO for inspections
• attend meetings of the Radiation Hazards Committee.
• arrange and ensure prompt distribution and collection of dose meters within the School.
• bring to the attention of the URPO any other matters of which he should be aware.
• act as Radiation Protection Supervisor in those areas where no other RPS has been appointed.

Within each laboratory working with open sources of ionising radiation the appointed RPS is responsible for ensuring adequate radiation protection procedures and training of workers in the area. In particular, the RPS is responsible for:

• ensuring that all workers within a particular group observe the Local Rules, Schemes of Work and Regulations.
• ensuring that suitable and appropriate training is provided for all radiation workers under her/his supervision.
• reporting to the SRPO any changes in the nature of the work carried out, and any incidents involving ionising radiations.
• keeping records of the acquisition of radioactive substances, their use and disposal, and providing such records to the SRPO as required
• informing the SRPO of new workers and helping in their training, and informing the SRPO of the cessation of radiation work by existing workers
• monitoring regularly, where appropriate and as laid down in the Local Rules, for radioactive contamination and leakage from equipment generating ionising radiations, and keeping records of such monitoring
• keeping a record of the location of sealed and unsealed sources, checking this inventory regularly at a frequency laid down in the Local Rules, and making these records available to the SRPO
• bringing to the attention of the SRPO any matter of which s/he should be aware.

Risk assessments must be made and local Rules and Schemes of Work written for each sphere of work involving ionising radiations to ensure that it is carried out in compliance with the Regulations. Copies of these rules and working procedures must be displayed in each laboratory and should be brought to the attention of all employees who may be affected by them.

It is the duty of the Head of School through the SRPO and RPSs to ensure that the local rules are adhered to and that all persons working in their School are properly trained in the safe use of all sources of ionising radiation.

It is the duty of each person whose work involves ionising radiations to ensure that the local rules are adhered to. Any person under the age of 18 or pregnant must consult the SRPO before considering any work with ionising radiations.

General Rules for Laboratory Use of Unsealed Sources

• All persons handling or using radioactive materials must be radiation workers registered with the University Radiation Services.
• At all times when radioactive material is being handled, full personal protection, a well-fitting laboratory coat, gloves and, where appropriate, eye and mouth protection, must be worn.
• Workers using 3H and 14C are not normally monitored (although in the case of 3H it may be necessary to assess internal dose using urine samples) and for 35S and 125I finger monitors are issued to new workers. Film badges are issued to users of 125I. Those using 32P must wear finger-monitors when handling undiluted or slightly diluted stock-solutions.
• The areas designated for use of radioisotopes handling are clearly delineated on laboratory plans available in each laboratory. Most of these are impervious surfaces, with a lipped front, but in some laboratories these benches are permeable and require covering in a suitably absorbent material such as “Benchcote” (absorbent side up). Non-designated areas must not be used for any work involving radionuclides.
• Work must be performed over drip-trays wherever possible.
• The normal restriction on eating, smoking etc applies to laboratories where work with ionising radiations is carried out.
• Anyone who has been handling or working with radionuclides in any form must wash his or her hands thoroughly before leaving the laboratory, even for a brief period. No one shall leave the laboratory wearing gloves that have been worn for handling radionuclides.
• All radioactive materials must be stored in a clearly marked, lockable cupboard or refrigerator when not in use.
• All dilution of radionuclides from stock solutions must take place at a designated site, which in the case of 32P, 35S, 22Na or 125I may be a controlled area.
• Transportation of radioactive materials from one laboratory to another should be restricted to the minimum. Radioisotopes must not be transported between buildings.
• All areas where radionuclides are handled must be checked regularly for contamination, following the guidelines in the Laboratory Rules, and a record made.
• Any contamination found must be removed, a record added to contamination records and both the SRPO and the URPO informed.
• Any accident or spillage, which involves radioactive materials, must be contained, the area sealed off and the SRPO and URPO informed immediately. Guidelines for dealing with spills and decontamination are available in all laboratories.
• Careful and complete records must be kept of all radioactive materials used, stating amounts drawn from stock and amounts disposed of, together with the method of disposal (sink, solid, scintillant). These records are collected by the URPO. The location of all sources must be known at all times.
• Once scintillant waste or counted tubes are deposited in designated containers for disposal the amount of radioactivity in the waste should be added to the sheet adjacent to the waste drum.
• Accumulation of waste material must be avoided. Waste is collected by the University Radiation Protection Service/URPO for storage and/or disposal.

Disposal of Ionising Radiation Waste

• Aqueous waste will be disposed of via a designated disposal sink leading directly to a sewer. The disposal amount and rate will be controlled by the availability of radioisotope and the protocols of the experiments. Care must be taken to ensure that licence limits are not exceeded. If there is any likelihood of the limit being exceeded, the RPA must be consulted before any disposal action is taken, in order that a protocol may be devised to prevent contravention.
• Solid and non-aqueous waste will be collected at the storage facility on Streatham Campus. Each container of waste will be identified by a unique serial number, assigned by the Radiation Service, when it is taken into the waste store.
• Very Low Level Waste (swabs, pipette tips, gloves, washed-out sample containers etc) must be collected in non-biodegradable white or black plastic bags of suitable robustness, double-thickness, held in a suitable waste-bag support (for radiophosphorus this should be a purpose-made box of acrylic of minimum thickness 7 mm, with a lid) labelled to indicate that radioactive materials only must be disposed of there, and where separate waste steams are maintained, to identify which bag is for which waste type. The bags themselves should not be marked as radioactive. When a bag is full, the Radiation Service must be informed, and arrangements made to collect the bag with minimum delay. When it is collected, the bag will be marked with a radiation symbol, which can be removed when it is finally disposed of.
• Each container of scintillation and other counted radionuclide samples must bear a radioactive warning sign and a legend identifying it as radioactive waste. It must have associated with it a schedule listing each disposal, with the activity disposed of, and a running total of activity in the container. When the container is full and passed to the Radiation Service for disposal, this schedule (or an exact copy thereof) must accompany the container at all times. On the container being taken into the waste store, the schedule will be assigned the same identifying code as the container to which it relates.
• Non-aqueous waste disposal routes as follows:
• Dustbin waste – pipette tips, swabs, gloves etc – are collected in bags, recorded, checked for radioactive emission and placed in dustbins at a controlled rate.
• Rapidly-decaying isotope waste (Phosphorus-32 and 33, Cr-51, I-125) will be separated from other isotope waste and stored for decay to minimise environmental impact. When it has decayed for a suitable period (such that the activity is demonstrably below the statutory limits) it will be disposed of to dustbin.
• Scintillation waste will be disposed of regularly to our licensed disposer, Shanks Waste Solutions at Fawley.

Permitted dose limits

These are laid down in the relevant guidance notes at the documents page of the Health and Safety office website, as follows:

• The limit on effective dose for any employee over 18 years of age shall be 20 mSv in a calendar year (but note there are further levels for equivalent doses for the lens of the eye and for the skin, and effective dose hands, forearms, feet and ankles)
• The limit on effective dose for any trainee under 18 years of age shall be 6 mSv in a calendar year (again with further (and different levels for the categories as noted above)
• In addition to both the above, the limit on equivalent dose for the abdomen of a woman of reproductive capacity shall be 13 mSv in any consecutive period of three months.
• The limit on effective dose for any person not an employee or trainee shall be 1 mSv in any calendar year.

The action levels on dose returns are specified as below for monitored workers:

• Zero dose return - no action.
• 0 - 0.5 mSv - await next dose return. If a second measurable dose is recorded, alert SRPO.
• 0.5 - 1 mSv - alert SRPO, request investigation and review of handling techniques.
• Above 1 mSv - initiate full investigation without delay.

Permitted holdings and disposal limits for unsealed sources

These are listed within the relevant guidance notes at the documents page of the Health and Safety office website.