Radiation Protection Today Winter 2021 - Page 30

Specialist Spotlight – Radon

Lynn Cooper is a Radiation Protection Adviser at Cavendish Nuclear Limited . She is a former Chair of the UK Radon Association .
To many health physicists , radon is considered more of a nuisance than a hazard in its own right . It ’ s the cause of false alarms in exit portals , due to radon ‘ plating out ’ on high vis or nylon clothing ; or high air sample results for which you must wait 24 hours for it to decay away and show , hopefully , that there was no airborne alpha contamination , at least not from the practices in the facility .
And maybe that ’ s because radon levels can ’ t be determined from these alarms on conventional Health Physics equipment . Understanding the risk and consequences of radon is a specialist niche which is often not on the syllabus for Health Physicists or Radiation Protection Advisers .
Monitoring requires specialist passive detectors , which must be analysed in accredited laboratories to provide results from a three month placement , and specialist knowledge to know when , where and how many detectors to place , and how to interpret the results and advise if and when the Ionising Radiations Regulations apply .
Radon gas is an issue that can affect buildings of any type , size , age or location . The average annual radon dose in the UK is 1.3 mSv , and as high as 6.9 mSv in Cornwall ! Workers on nuclear sites are likely to receive more dose from radon exposure than from other work activities .
UKHSA ( UK Health Security Agency , formerly PHE , HPA and NRPB ) publishes reports and an interactive map presenting the probability
Radon is a radioactive gas formed when uranium in the soil and rocks beneath us decays . When it permeates the ground into open air , it is quickly diluted to low concentrations , however if it rises into a building , it can become trapped and build to dangerous concentrations .
of properties being affected by radon . Areas where it has been estimated that more than 1 % of properties will contain high levels of radon are classed as radon Affected Areas .
Buildings with basements are also more susceptible to high levels of radon accumulating , as there is a larger surface area in contact with the soil through which the gas can permeate . UKHSA advise that any property with a basement , regardless of whether it is located in an Affected Area or not , will have an increased probability of containing high radon concentrations .
To assess the level of radon in an existing building , a test must be conducted using a passive radon detector supplied by a validated laboratory ; a list of these is available from UKHSA . If the test results show that the radon level in the workplace exceeds
3
300 Bq / m ( annual average ) the Ionising Radiations Regulations 2017 ( IRR17 ) apply and the employer must notify HSE .
A radon detector in situ ( photo courtesy of Cavendish Nuclear Limited )
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