Instrumentation for the Early Phase
Survey meters currently used by the Fire Services based on energy-compensated Geiger-Muller detectors with dose rate ranges up to 0.5 mSv/h would be suitable for measurement of dose rate at locations selected with a wide distribution throughout Hong Kong. The measurements of dose rate should be made in the open, at least 20 metres from the nearest building with the monitor held approximately one metre above the ground. This monitoring programme should be organised and administrated by the Royal Observatory in conjunction with the Fire Services Department.
The provision of battery-operated air samplers for these locations should also be considered, together with glass fibre filters and activated charcoal or silver zeolite sampling packs. (Battery-operated air-samplers typically sample at 10 litres per minute. Higher volume samplers would be preferable provided power supplies are available). Filters and charcoal or silver zeolite packs should be changed at hourly intervals and retained in plastic bags for delivery to the King's Park Radiation Laboratory or other predetermined laboratories. It should be noted that an air sampler rated at a nominal, say, 10 l/min is likely to actually sample at a reduced rate if an activated charcoal or silver zeolite pack is being used. This sampling programme should be organised and administered by the Environmental Protection Department, who have expertise in air sampling techniques, in conjunction with the Royal Observatory.
The mobile monitoring teams will require hand-held monitors and battery-operated air samplers. Geiger-Muller or other suitable survey monitors with ranges 0-0.1 mSv/h and 0-2 mSv/h are recommended. A suitable instrument should be provided for measurement of beta contamination. This should be either a Geiger-Muller or a scintillation probe with a suitable ratemeter.
The emergency monitoring equipment for each vehicle should be stored in convenient containers ready for loading when required. Each vehicle should be manned by a driver and radiation surveyor, who will require some basic training in the use of monitoring and sampling equipment.
Protective clothing (of the normal industrial type eg cotton overalls) and respirators should be provided for personnel manning survey vehicles. It is not expected that the respiratory equipment would be worn in the general course of emergency monitoring, but it would provide reassurance that survey teams could continue to operate for long periods in all conditions, even if the general public had been instructed to shelter.
An inventory of equipment to be provided in survey vehicles is given in Appendix II.
Monitoring and Sampling Equipment, and Techniques, for the Intermediate Phase
During the intermediate phase sampling teams will be required to collect samples of vegetation, milk, crops, surface and drinking water, and soil samples. Samples will be returned to the Radiation Laboratory at King's Park, or other predetermined laboratories. An inventory of the equipment which will be needed by sampling teams is given in Appendix III. It is important that sufficient sample containers to cover at least one week of high intensity sampling should be available, and preferably this emergency stock should be maintained separately from the routine stock of sample containers. Suggested stock levels may need revision according to local conditions and should be reviewed after experience has been gained on the background monitoring programme and emergency exercises.
Grass samples should be cut from a measured 1 m2 area, and to within 20 mm of the ground. Samples which are to be analysed for iodine or other volatiles should be placed in glass containers and sealed. Other samples may be sealed inside polythene bags. Soil samples should initially be taken from a defined area to a depth of 20–30 mm using a trowel. Later, in the intermediate and recovery phases, samples should be taken to a depth of 200 mm using a core sampler. Water samples can be taken using polythene containers. A simple device will be needed to take
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