FIXED SURVEY METERS
RADIAC SURVEY METER No.2
The Radiac Survey Meter No 2 or RSM was a 1955 meter which counted the particles produced by radioactive decay. This meter suffered from a number of disadvantages: it required three different types of obsolete batteries, it also contained delicate valves that were liable to failure and it had to be operated from outside the protection of the post. These were favored as they had been tested on fallout in Australia after the Operation Buffalo nuclear tests, and remained in use until 1982 by commissioning a manufacturer to regularly produce special production runs of the obsolete batteries. Within the ROC the RSM was only used at post sites for three years when it was superseded in 1958 by the FSM and the RSM retained only for post attack mobile monitoring missions.
FIXED SURVEY METER
The Fixed Survey Meter or FSM introduced in 1958. The meter was operated from within the post mounted on the main desk with a cable leading from the meter up to the detector which was mounted externally through a hole in the monitoring post ceiling and protected by a polycarbonate dome (see diagram below). The FSM used the same obsolete high voltage batteries as the RSM. During the mid-80s this instrument was gradually replaced by the PDRM-82F which was manufactured in 1982.
Image kindly supplied by James Sansom
PERSONAL DOSE RATE METER (PDRM-82F)
The PDRM-82F was the fixed desktop version of the new Portable Dose Rate Meter, as manufactured by Plessey and introduced during the 1980s. The unit gave more accurate readings than its predecessor and used three standard 'C' cell torch batteries that lasted many times longer; up to 400 hours of operation. The compact and robust instruments were housed in sturdy orange coloured polycarbinate cases and had clear liquid crystal displays. The PDRM-82F had a remote sensor, mounted above ground under a polycarbinate dome and connected down a steel probe-pipe to the instrument by a coaxial cable.
The radiac sensor was self contained within the casing. All the electronics including miniature geiger tube (shielded against beta particles) was incorporated onto a single EMP-hardened, PCB. It is microprocessor controlled with digital readout. For use for mobile radiation analysis by the Royal Observer Corps and other Civil Defence / emergency teams the instrument was also provided in the mobile version designated the PDRM82(M).
The radiac sensor was self contained within the casing. All the electronics including miniature geiger tube (shielded against beta particles) was incorporated onto a single EMP-hardened, PCB. It is microprocessor controlled with digital readout. For use for mobile radiation analysis by the Royal Observer Corps and other Civil Defence / emergency teams the instrument was also provided in the mobile version designated the PDRM82(M).
FIXED SURVEY METER TRAINER
The Fixed Survey Meter Trainer is a battery operated Radiac simulator designed to replace the Geiger Muller Tube of the Fixed Survey Meter for training and exercises only. The unit will simulate the pulses transmitted by the Geiger Muller Tube using a module (known as an EPROM) and which has been programmed by the Exercise Preparation Sector at HQ UKWMO and this producing on the FSM readings which the instrument would display had these levels of radiation been present.
Information Source: Thanks to the supplier to Wikipedia