the complete package for radiological, chemical & asbestos characterisation

Laser sampling using ViridiScope®

ViridiScope is the laser sampler that can be operated manually or remotely. The control system has been designed to be mobile with a 20-metre-long umbilical to allow the sampling head to be taken into areas of high activity or inaccessible places. The head is connected to the control system, via the umbilical carrying the optical fibre carrying the laser power, the signal cable and disposable nylon tubing. Surface material ablated by the laser is transported through the tubing under vacuum, collected on filter paper in a disposable sealed pod, and the mass of each sample is weighed accurately.

The sampling process is controlled by the operator when sampling manually, or from the control system when used remotely. The lightweight head can be attached to a telescopic rod or deployed on remotely operated wall climbers and robotic arms for deployment in very difficult to access areas and in areas of high radiation.

ViridiScope has been tested on radioactively contaminated concrete, plaster and brick. Mild steel, stainless steel, and galvanized surfaces have been tested in a non-operational environment. Sampling time is pre-programmed between 0.5 to 5 min using 30 s increments and, routinely, sampling times are 2-5 minutes to collect 0.1 g of sample, depending on the nature of the surface material. The sampled surface 1-2 mm wide and 2 mm deep, and 300 mm long, about 1 cm3. The maximum amount of material sampled in a pod is 2 g, which requires 90 min collection time. The sample can be characterised as soon as it is collected, in situ, using portable instrumentation. Gamma spectrometry is carried out directly on the sample pod with a portable high-resolution germanium detector for Am-241, Co-60 and Cs-137. The pod lid is then removed, and the filter counted for total alpha and beta measurements with a portable gasless proportional counter or a PIPs detector. The sampling and counting process takes around 30 min for ILW and LLW.

ViridiScope delivers samples in a form that can analysed by inductively coupled plasma mass spectrometry ICP-MS in situ following a short preparation stage. An automated microwave sample preparation unit is used to convert the particulate sample into a liquid form ready for analysis to provide an integrated on-site solution for isotopic and chemical (elemental) characterisation. The equipment including the automated mass spectrometer is mobile. Typical cycle time from collection to result is 25 min per sample. Mobile asbestos testing facilities can provide rapid asbestos characterisation for amosite and chrysotile in asbestos insulation board and asbestos cement samples collected using ViridiScope. Transport of samples off-site is avoided, and turnaround times are rapid. Remote deployment on a wall climbing ROV for example make this a very attractive approach to sampling for asbestos at height without the need for scaffolding.