Selecting PPE1 August 2019
Stephen Watkins explains how to assess radioactive risks and select appropriate protective garments.
IONISING RADIATION EXPOSURE IS THE primary hazard when working with radioactive substances, but residual contamination — through exposure to particulate dusts via inhalation or direct skin contact — also poses a serious health risk to those working in the nuclear industry. For example, exposure can occur where residual radioactive contaminated particles such as dusts and silica are released into the air during nuclear plant operations and decommissioning. Workers can also be exposed through chemical splash and liquid chemicals, such as sulphuric or nitric acids and sodium hydroxide — all of which are irritants and corrosive to skin tissue — and/or radioactive contaminated chemicals, water or other fluids. So workers involved in nuclear research and testing, site inspections, reprocessing, decommissioning and general maintenance are at risk of contamination. Where a worker cannot avoid exposed to radioactive contaminants, it is necessary to minimise contamination risk through the correct use of personal protective equipment.
Disposable protective garments with suitable respiratory protective equipment is a way to avoid long-term exposure to radioactive contaminants. These garments are designed to be worn in potentially affected areas and then promptly removed and disposed of under controlled conditions, minimising long-term exposure to contaminated material. Protective clothing should minimise both the number of particles that are able to penetrate the garment or transfer with other substances by permeation, and offer the maximum level of comfort during performance of their tasks. In general, the more body coverage, the better: hooded coveralls help keep clothing and hair free of radioactive materials.
The key parameter to consider when comparing the particle resistance of protective clothing is inward leakage (IL%). This indicates how many fine particles would be able to penetrate the protective garment system — the lower the number, the better the level of protection.
Garments should be tested in accordance with standard EN 1073-2 for protective clothing against radioactive particulates and contamination. The test determines the inward leakage and the barrier efficiency of the garment when challenged with a fine salt solution of 0.6 microns.
When considering a garment’s suitability, pay particular attention to potential ‘entry points’. By their nature, most garments are stitched. It is worth checking that the protection around the seams is the same standard as that offered by the main material.
Other factors to take into consideration include environmental conditions, such as humidity levels.
Using these general parameters, let us look at three scenarios.
For dry, residual radioactive particle hazards, a hooded, disposable coverall provides Category III protection from dry radioactive particles as defined by EN1073-2. Our option also offers Type 4 protection from liquid mist and aerosols without compromising on comfort. Stitched and over-taped seams minimise the likelihood of any contaminated solid particulates or liquids coming into contact with the wearer or their clothing. It has thumb loops and cased elastication at wrists, ankles and face. The front opening is protected with a self-adhesive zipper and chin flap, and the garment can be specified with or without integral socks.
In some cases, operator comfort could be compromised by high humidity — for instance via pressure contact with wet, potentially contaminated surfaces (such a kneeling) — as well as radioactive particulate contamination. Our solution is a breathable Type 3 coverall for protection against water-based inorganic chemicals under pressure. Lightweight and ergonomically designed, with elastication at wrists, ankles and face, a zipper with self-adhesive overflap and over-taped seams, it is suitable for waste clean-ups.
For situations where the main risk is from liquid chemicals that have been radiologically contaminated, a single-use coverall, hooded for head to toe protection and ergonomically designed will provide users with comfortable protection against biohazards, inorganic chemicals and hazardous liquids. It must offer Type 3-B, 4, 5 and 6 barrier protection.
The mature nature of the nuclear sector means that the potential hazards to personnel from exposure to radioactive contamination are well understood. Specific regulations are in place that clearly lay down how protective apparel must be tested and classified to mitigate such risks. In addition, manufacturers of PPE can give additional reassurance to specifiers. DuPont has an online tool which helps specifiers to identify the best match of garment, gloves and accessories for their application.
Author information: Stephen Watkins, Account Manager for DuPont Personal Protection