Fownhope ROC Post, Herefordshire 2021

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callumcrom00

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All surface features remain intact although only one ventilation louvre is still in place. The FSM pipe is raised on a concrete plinth. The hatch is partially detached, unusually for an early closure its internal lock is still in place and still works. Internally twin bunks and a single bed. cupboard, folding table and shelf remain in place.

The post opened in 1961 and closed in 1968.
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Hayman

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Again showing my ignorance - and lack of ability to guess the answer - what is the "FSM pipe"?
 

talkpoppycock

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Again showing my ignorance - and lack of ability to guess the answer - what is the "FSM pipe"?

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 Within the ROC the RSM was only used at post sites for three years when it was superseded in 1958 by the FSM and the RSM retained only for post attack mobile monitoring missions.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.

 

Hayman

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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.

Many thanks for the detailed explanations. Having seen so many films and TV programmes featuring the well-known hand-held and usually clicking Geiger (or Geiger–Müller) counters, it’s educational to know about the Fixed Survey Meters.

Since they were used in static situations, I’m surprised the earlier fixed survey meters were not adapted to take standard, easily available batteries, or even to use mains voltage and transformers – with battery power simply as an option. Accumulators could have been kept charged from the mains until needed.
 

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