Radon is a naturally occurring radioactive gas that is present in the outside atmosphere and commonly has higher concentrations in business premises, homes and caves. The concentration of radon in the Poole’s Cavern air is continuously monitored, and the concentrations are used to calculate the radiation dose accrued by anyone entering the cave. Visitors accrue a negligible dose and although the dose accrued by employees is a bit higher it is within the limits specified by the Ionising Radiations Regulations, part of the Health & Safety at Work Act. The sources of the radon are still not fully understood and one question is whether water entering the cave degasses, releasing radon gas into the cave air, or whether the water dissolves radon and takes it out of the cave. A recent collaborative project with Durridge will, hopefully, help to provide answers.
Durridge manufacture instruments capable of measuring radon concentrations in air and in water, including the RAD8 which has been optimised for use in rugged environments. Durridge has recently redesigned the RAD8’s Water Probe accessory, and would like to establish how well this compares with the original design in a real-world situation. Dr Stephen Sadler, Durridge Chief Scientific Officer, contacted Professor John Gunn who has wide experience of radon monitoring and they agreed that the British Cave Science Centre at Poole’s Cavern would provide an ideal environment for the test. On 12 December Steve and John visited Poole’s and two RAD8 radon monitors were installed where the nascent River Wye enters the cave, one with the new-style Water Probe and the other an old-style probe.
On 17 December the probes were swopped over so that each monitor will have a period collecting data with an old probe and a period with a new probe. Once Durridge has assessed the data, the plan is to leave one RAD8 at the upstream end of the cave and to move the other to the downstream end, adjacent to the stream sink. By comparing data from the two monitors, it will be possible to quantify how much radon the water is gaining or losing as it flows through the cave.
Comentários