Radioactive contamination in scrap in metal recycling

Introduction

This guidance is targeted at those who operate or manage metal recycling facilities. At these premises there is a potential for radioactive materials to be found in consignments of scrap metal.

Ionising radiations occurs as either electromagnetic rays (such as X-rays and gamma rays) or particles (such as alpha and beta particles). People can be exposed externally, to radiation from a radioactive material or a generator such as an X-ray set, or internally, by inhaling or ingesting radioactive substances. Wounds that become contaminated by radioactive material can also cause radioactive exposure.

Artificial sources of ionising radiation have many uses in industry, such as energy production, construction, manufacturing processes, medical and dental and research. It is important that the risks of ionising radiation are managed sensibly to protect workers and the public.

Application of health and safety legislation

HSE regulates work with ionising radiation to ensure that workers and members of the public are not harmed by these activities. The Ionising Radiations Regulations 1999 (IRR99) Approved Code of Practice (ACOP) will apply in circumstances where radioactive contamination is found in scrap metal. In such circumstances there is a duty under IRR99 to inform HSE (by email [email protected]).

The Management of Health and Safety at Work Regulations requires an employer such as a medium to large scrap metal dealer/processor, to carry out a risk assessment covering their work activities. This should include an assessment of the risks associated with the handling of potentially contaminated radioactive material. Unless the material brought onto the premises can be assured to be free from radioactive material, the employer may need to install a portal/weighbridge monitoring system to minimise the risk to his/her employees from exposure to radioactive contamination in scrap metal.

The employer will also need to have written action/contingency plans describing what to do in the event of an alarm, source characterisation procedures, and contact details for local Environment Agency (EA), Scottish Environmental Protection Agency (SEPA) in Scotland, Department for Transport (DfT) and the appointed Radiation Protection Advisor (RPA) for advice.

It is vital that these procedures cover conditions under and arrangements for authorisation for return of contaminated loads to suppliers; this most only be done in accordance with relevant legislation enforced by the EA/SEPA, DfT and HSE.

What is radioactive contaminated scrap? Where is it from?

There have been many incidents worldwide including in the UK, where radioactive materials have become incorporated into the scrap metal chain. The radioactive material tends to originate from the following sources:

• 'Orphan' radioactive sources – these are radioactive sources that are out of regulatory control and typically come from redundant industrial equipment such as gauges used for process control. They are likely to contain the following radionuclides, caesium-137 (137Cs), cobalt (60Co) or americium-241 (241Am) in various quantities. The radionuclide will be encapsulated in a small (typically a pellet a few mm in size) very tough stainless steel capsule to form a "sealed source" Gauges will take the form of a shielded container with the radioactive source held inside. Industrial radiography sources such as iridium (192Ir), and depleted uranium (238U) source containers may also be encountered. Redundant or waste radioactive sources from medical applications and old dials and gauges luminised with226Ra have also found their way into the scrap metal chain.
• Naturally occurring radioactive material (or NORM) or low specific activity (LSA) scale - NORM typically contains uranium-238 (238U) and thorium-232 (232Th) and their associated radioactive decay products. Typical sources are zircon sands or refractory materials. LSA scale containing radium-226 (226Ra) and its radioactive decay products can accumulate on the inside of items of plant involved in certain chemical processes and from the oil and gas industry. Scrap metal or items of plant such as pipes can be contaminated with significant quantities of LSA scale. In addition, natural thorium, which contains radioactive thorium-232 (232Th), is used in various alloys for specialist applications (eg aerospace) and welding rods. Scrap metal containing enhanced levels of these naturally occurring radionuclides can find its way into the metal supply chain.
• Nuclear material - material originating from the nuclear fuel cycle has occasionally been found in the scrap supply chain. Whilst most countries with a nuclear industry have very rigorous controls over the release of potentially contaminated scrap metal for recycling, lack of controls in some countries,  has resulted in high value scrap such as stainless steel or copper contaminated with radioactive material reaching the UK market
• Imported steel – there have been incidents more recently when steel imported into the UK has contained radioactive material as a result of an orphan source being melted with the steel during the production process.

What are the hazards and risks?

Radionuclides (an unstable form of a chemical element that can emit nuclear radiation) undergo radioactive decay, giving off a range of ionising radiations which can interact with the human body causing damage to cells which may result in an increased risk of developing cancer. The nature of the hazard depends upon many factors such as:

• the particular radionuclide present;
• how much is present (measured in becquerel (Bq) the unit of radioactivity or 'source strength');
• the type of ionising radiation it gives off when it decays and how that radiation interacts with the human body; and
• the distance from the source.

The risks can be grouped into two categories:

• External radiation. Sources such as137Cs,60Co,226Ra,192Ir and  241Am give off  gamma rays which can pass through air over great distances (100s metres), and even to a limited extent through steel, lead, concrete etc as well as passing through the human body. Hence, even though the radioactive material is outside the human body and perhaps several metres away, a person may be exposed to a significant dose of ionising radiation with the potential to cause harm. Factors affecting the degree of risk include: the radionuclide and the activity of the source, distance from the source, shielding around the source, and time spent in the vicinity of the source. However, all the above sources have the potential for considerable risks to employees in the scrap metal industry if they are encountered.
• Internal radiation. Radionuclides can be incorporated into the body by ingestion, inhalation and through the skin (absorption, cuts and grazes) following contact with radioactive contamination. In particular, LSA scale or NORM contaminated dusts may be generated during handling or processing of scrap and breathed into the body.

Where will the hazards arise in the workplace?

Sealed radioactive sources are usually housed in an outer casing or container which acts as a shield to the radiation. 'Orphan' sealed sources from redundant industrial plant can present an immediate hazard in the scrap yard if this shielding is missing or damaged on initial receipt. They may present little risk if the container is properly closed and locked.

When scrap is processed and sorted by fragmenting, shearing, milling, cutting, etc, there is a potential for loss of shielding and subsequent significant exposure of employees to external radiation. Loose radioactive material can then contaminate large areas of processing plant including scrap yards with significant potential for exposure of operatives to internal radiation by ingestion or inhalation. If a source is ruptured during smelting, the linings of furnaces, slag- handling facilities, bag houses and the actual product can all become contaminated. Shutdown and decontamination of plant can be very expensive and time consuming.

The processing of NORM and LSA scale contaminated items and contaminated scrap from the nuclear fuel cycle can also present a contamination hazard and internal radiation risk in the workplace. 

Recognition

Ionising radiation cannot be detected by human senses

Isotope holders or containers come in a wide variety of shapes and sizes. An important indicator that a source may be present would be the presence of the international symbol for radiation (the 'trefoil'). The symbol is usually a black pictogram on a yellow background.

The source container may also be marked with the word 'radioactive' along with an indication of the radioisotope present and the activity in Bq.

What can be done to reduce the risk? Use of monitoring, alarms etc.

Unless the scrap is obtained from known sources which are highly unlikely to be contaminated, there could be a degree of risk of orphan radioactive sources or contamination in the product. The risk can increase if the scrap originates from premises where radioactive materials are, or have been used. It can be further increased where higher value material (eg stainless steel, copper scrap) is imported into the EU from countries where controls of radioactive material may be less rigorous.

Loads entering the scrap chain can easily be scanned for external gamma radiation by passing vehicles through a portal monitoring system, often installed at the weigh bridge.  Upon detection of radiation, an alarm will sound to alert the operator. More sophisticated systems are available which will also indicate the likely position of the source(s) within the load as well as an indication of the radionuclides present in the load.

It is normal practice to monitor product on both entry into and exit from the premises, since monitoring is not guaranteed to detect the presence of a very well shielded radioactive source or radioactive contamination buried deep inside the load, where the load itself can effectively shield the source from detection.

Procedures in the event of an alarm

The priority when radioactive items are found in scrap metal is that the material should be brought under a system of control to enable it to be assessed and disposed of appropriately

The operator should have procedures to be followed in the event of an alarm. Normally the operator should have to:

• re-run the vehicle through the monitor to confirm alarm;
• isolate vehicle in designated position;
• investigate the vehicle using a hand-held gamma dose rate meter to establish if it is safe to approach the vehicle, and cordon off the area around the vehicle where the dose rate exceeds, say, 7.5 microSv/h; 
• contact the radiation protection adviser (RPA) to seek further advice re safe handling, isolation, storage and disposal of source(s) or contaminated item(s);
• inform a local office of Environment Agency (EA), Scottish Environmental Protection Agency (SEPA), Department for Transport (DfT), the consignor and HSE.

Contact details

Environment Agency (EA):

For general enquiries in office hours: 03708 506506
For reporting an incident: 0800 807060

Scottish Environmental Protection Agency (SEPA):

For general enquiries in office hours locate the local office via their website

For reporting an incident: 0800 807060

Contact details and guidance from the Department for Transport (DfT) can be obtained on their website.

The load should only be allowed to return to the road if the cause of the radiation alarm has been properly characterised, and it is safe to do so under the guidance issued by the regulatory bodies above. Otherwise, the vehicle should remain isolated at the recipient's premises until it can be made safe by competent persons.

If the vehicle driver refuses to allow his vehicle to remain at the recipient's premises both he and the consignor should be made aware of the hazards to himself and other persons. The police should also be informed.

What is industry doing?

The major players in the industry are aware of the potential health and safety, and commercial risks associated with radioactive contaminated scrap. Some have installed monitoring systems, and have supporting procedures in the event of an alarm.

The main Trade Associations dealing with this industry include the British Metals Recycling Association (BMRA).They have produced supporting information and guidance which is available to their members. In addition, posters and information booklets have been produced by the association and the EA, primarily aimed at highlighting the risks from radioactive sources - how to recognise them, what to do etc.

An additional factor in the provision of monitoring systems has been the requirement of major purchasers of scrap metal for the supplier to declare that the consignment is free from radioactive contamination. In reality, this requires the supplier to monitor prior to shipment. In turn, this is now cascading down the supply chain to the medium-sized suppliers. As a result, there is a trend towards the installation of monitoring systems at various stages in the supply chain.

What you need to do

• carry out a risk assessment covering the possibility of radioactive contamination has been carried out;
• install an appropriate portal/weigh bridge (or other) monitoring system;
• ensure that there are arrangements for checking and testing of any monitoring system and action plans available covering required procedures in the event of the discovery of radioactive contamination in scrap metal (including source characterisation, recovery, temporary storage arrangements and source disposal, availability of hand held radiation monitoring equipment)?;
• appoint a suitable RPA been to assist in implementing the above procedures?;
• provide weighbridge operators with sufficient information, instruction and training to ensure they are able to implement the above procedures? and
• have a system in place that will enable the return/isolation of loads suspected of containing contamination in accordance with relevant regulatory requirements.

For further information on Radiation visit the HSE website.