Dosimeter Recharging Units

During the Cold War the British Army used quartz fibre dosimeter units for determining radiation exposure. These were small cylindrical items that had a small pen loop on them and could be easily carried by a soldier and indicated their cumulative exposure to radiation. These early dosimeters slowly lost their effectiveness as they were exposed to background radiation or indeed actual radiation on the battlefield and needed to be recharged to restore them to their base line settings. This is explained in a 1972 pamphlet:

The quartz-fibre, which is very thin, is formed in the shape of an elongated ‘U’, the ends of which are attached to a thick wire similar in shape. When charged with electricity the quartz fibre moves away from the wire, i.e. towards zero on the scale.

When the dosimeter is taken into a contaminated area radio-activity causes the electric charge to leak away and the quartz fibre to move back towards the wire and up the scale from zero. The stronger the radiation or the longer the exposure to radiation the greater will be the leakage and the higher the reading on the scale. Those in the same contaminated area for the same time will absorb similar doses.

In order to restore the dosimeter’s settings a small recharging unit was used which was a metal box, about 6″x4″x3″:

The dosimeter charging unit has a small port in which the dosimeter is fitted when recharging. This is normally protected by a plastic cover that can be pulled up and off for access:

A dial is fitted that is rotated to reset the dosimeter by releasing a small electrical charge into the dosimeter:

The base of the charging unit has a large screw for access and the patent number cast into the metal:

A small data plate is fixed to the front of the charging unit:

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