British Army Personal Wrist Watch Dosimeter

Amongst the many items of personal NBC equipment issued to British troops is a small wrist watch type personal dosimeter used to record the levels of radiation the wearer is exposed to. This personal dosimeter is officially called a ‘Radiacmeter Personal Locket Dosimeter’ and it uses a radiophotoluminescent glass and pin diode in a lead lined nylon wrist locket:imageThe dosimeter doesn’t have any way of being read by the wearer, and requires a separate dosimeter reader. The dosimeter is worn on the wrist, over the NBC smock and gloves, and is secured with a nylon strap and metal buckle:imageAs it can’t be zeroed after reading, it needs to be worn by the same person at all times to get an accurate reading, therefore a unique serial number is inscribed on the back:imageThe instrument measures from 0-1000 Roentgens and indicates the total absorbed radiation of the soldier. As with most modern equipment a unique NSN number is embossed on the front:imageThese personal dosimeters were issued in sealed packets, only to be opened and worn when required. They are also worn by those involved in MoD jobs where radiation might be encountered and the following guidance is given to wearers on their use:

The individual wearing the dosimeter must:

Wear it properly in the radiation area;

Store it in a low background area, remote from any known sources of ionising radiation when not being worn;

Not shield it in any way. Pens, rulers or other metallic objects may shield the dosimeter;

Not immerse the dosimeter in any liquid. Particular care is to be taken to remove dosimeters from clothing before laundering. Divers are to wrap their dosimeter in two plastic bags and wear the dosimeter inside their wet suit;

Keep the dosimeter away from high temperatures, e.g. pipes and radiators;

Not share the dosimeter with anyone else;

Not damage the dosimeter or holder in any way;

Not carry the dosimeter in close proximity to luminised watches or other luminised articles;

Return the dosimeter promptly at the correct time, ensuring that a replacement is available before giving up the old one, if necessary;

Notify the supervisor, RSO or RPS immediately, if it is lost or mislaid, especially in a radiation area (even if it is later found) as the employer may need to estimate the individual’s dose;

Ensure that the dosimeter is not worn inadvertently during medical/dental X-ray examinations.


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