[Thruster763]

Hi,
I'm new to the forum, but would like to comment on this subject. While it is unfortunate that the instruments were confiscated, I must say that keeping this number of instruments in a living space is a very bad idea. Assuming the instruments are not broken or disassembled, the biggest problem is Radon (222Rn) gas. This is a decay product of the Radium. It deposits it's own decay products (including radioactive Lead and Polonium) in the lungs. This causes direct radiation to delicate tissues and can cause lung cancer. Turn and Bank (slip) indicators are one of the worst offenders. They can have large areas of paint behind the slip bubble, and a large air intake area for the Radon to escape.
The UK HSE recommends an "Action Level" of 2.5uSv/hr radiation exposure rate at the pilots seat of an aircraft with radium instruments. This would also be a good guide for the radiation at the normal viewing distance from a display. Most importantly owners should under NO circumstances try to remove the radioactive paint to make the instrument "safe". This will just spread contamination around the work area and possible internal contamination. If an instrument is broken, use disposable gloves and seal it in at least two plastic bags.
Disposal is a big issue, in the UK there is no permanent disposal site for Radium, it has to be stored. Don't keep instruments in occupied areas especially bedrooms. Storage should be well ventilated. On Geiger counters, it's hard to recommend anything specific, but I can give some definite no's. Don't use the Plessey PDRM-82 series that are cheap on ebay. they will not give any response below that which is a serious and immediate threat, certainly not the "hottest" aircraft instrument. Also avoid ex-military RADIAC meters. Most are too insensitive or are too old to be reliable. To measure the dose rate (amount of exposure), make an assessment (not even reasonably accurate measurment) of the quantity and check for contamination would require at least two, probably three quality instruments (possibly one instrument with two or three specialised probes). This is not a job for a cheap ex soviet radiation meter bought on ebay. While I personally think the risk from instruments is small, there a principle called ALARP (As Low As Reasonably Practical) for radiation exposure, this means the authorities take different and variable views. ALARP is a good idea. Unfortunatly while the risk is low, the benefit of collections is also low (in the eyes of the regulators). A quick disclaimer, I'm not a radiation expert, but a keen hobbyist. I'm also a licensed avionics engineer and have worked in instrument repair shops.

Robert.