How safe are our collections?
 

Hi the home made testers from a member show on the outside of box the radiation is 6.04 usv/h . reading close to switch a reading of 52.2usv/h. This is from the Radium in the ex RAF switch this led me to check other items i have 3x meters no longer glow 5x glow in the dark round lights that have been glowing for the last 20+ years and they are very bright still. and last a Tilly lamp the gas mantle is doped with thorium. The meters read 30.2 usv/h 27.3usv/h and 36.7 usv/h with a sbm20 tube so beta or gamma radiation. Background is 0.07 to 0.09usv/h all the above items are ex mill and all trigger the alarm that is set at 500cpm . before anyone asks i have no super powers ?
yet Mick

Re: how safe are our collections
 

if the reading are right at close range to the switch the reading is 449msv/yr
the exposure for a nuclear power worker is 20msv/yr. But keep in mind this is at a very close distance less than 1 inch would still keep out of harms way and not sit close for long periods of time Mick

Re: how safe are our collections
 

Thorium decay is principally an alpha emitter. Top layer of skin stops it, but any ingested is the real danger.

Just been doing some TIG welding this afternoon. Thoriated tungsten electrode...

David

Re: how safe are our collections
 

I am very aware of the radioluminescent paint on aircraft instruments, clocks, compasses and some military radios. I usually test anything that comes in to determine if radium paint is present. I have some uranium glass articles that although give a high reading close up are quite safe to handle since the uranium is "glassified". I just walk past any stall that has luminous instruments or clocks with broken or missing glass, and I would not go near some items that are literally encrusted with radium paint. On balance, the body is quite capable of dealing with a certain level of radioactive contamination, but there is obviously a break point where the body can not cope. A really hot item is the WWII marching compass made by The Gramophone Company, I still have mine, but it is well sealed and is just used as a test source.
Neil

Re: how safe are our collections
 

I think it's reasonable to say that the only people judged to be at significant risk from Thorium doped mantles were those who worked in the factory that made and packaged them.

Radium paint is a bigger deal.

Uranium glass varies- mine isn't much above background and is of no concern. It glows like mad under UV. I have read that much of the radiation originates from impurities rather than Uranium- hence the variation in emission.

Dave

Re: how safe are our collections
 

I remember one of my science teachers showed us how a Geiger counter would react to a watch with a Radium painted face. Even the old tobacco tin it was stored in would cause some clicking.

Re: how safe are our collections
 

I inherited a Pentax SLR that has the radioactive f/1,4 50mm Super Takumar lens. Apparently the radioactivity emissions are greater than the present normal allowable limit, but an exception has been made for lenses as there is no substitute for the properties that the radioactive stuff gives to optical glass. Apparently the emission is back towards the film, not forwards, and is insufficient to fog film. On the other hand, the wartime long focus Aero-Ektar f/2.9 , that was often advertised in the photo magazines in the 1960's for use as a cheap telephoto lens, is definitely "hot", and should not be kept under your bed if you want to start a family!

In the late 1950's, my cousin had a South African pen-pal whose father worked in a Uranium mine. She once posted my cousin a matchbox containing some small lumps of crystalline Uranium ore. They resembled irregularly-shaped dirty yellow sugar lumps, and we often used to play with them. I still have the remains of a 100ml bottle of Uranium intensifier that I used to treat under-exposed negatives when I was a schoolboy. I just used to immerse the film in the solution using my fingers. A chemist friend thought it would have been safe enough, as the highly radioactive isotope of Uranium only exists as a very small proportion in the unrefined stuff, and I haven't triggered any alarms in subsequent visits to nuclear power stations.

Re: how safe are our collections
 

Even in the 1950s the issue of radioactive dials was a 'hot' issue, plenty of WWII surplus stuff had its meters removed before it was sold down Edgware Road or Lisle Street.

They didn't seem so worried about ex-paratroopers' wristwatches many of which were just as dangerous.

There's a beach on the north coast of Scotland where surplus aircraft were dismantled/burned in the late 40s, they still occasionally find radioactive particles in the shingle.

Re: How safe are our collections?
 

Not quite the north coast of Scotland it was Dalgety Bay on the North shore of the river Forth.

There is loads of information about it on the internet e.g. https://www.sepa.org.uk/regulations/...s/dalgety-bay/

Al

Re: How safe are our collections?
 

Quite close to me. Dalgety bay is now a very large estate of houses, a small town. They don't occasionally find significant radioactive lumps, the beach is riddled with them and is far far overdue for a painstaking clean-up.

It's only about 12 miles from Edinburgh, as the Gull flies.

The place on the North coast of Scotland, is Dounreay, the site of the fast-breeder reactor where they kept shoving waste down a disused well and had a typical variety of radioactive whoopsies. No aircraft were harmed in the making....

David

Re: How safe are our collections?
 

This has some interesting reading:
https://www.bvws.org.uk/405alive/tech/safety.html

Re: How safe are our collections?
 

Hi Richard. You once visited Ramsbottom for a very enjoyable day, buying one of the Marconi series Marine Radio's [you are an impressive electronics expert and vinyl archivist] from me and enjoying a lunch that included Thwaites bitter:beer:. Unfortunately Covid and latterly, my daughter's illness has meant a lack of contact which I still hope to re-establish. I'm just making a public comment on here to put [perhaps] mickm's genuine concerns in context. At one point, in my social work career, we were given a building to convert into a Family Therapy Centre. We breached the structure as volunteers [cutting in viewing windows etc] but it was later totally condemned and isolated due to blue asbestos8-o. So far. as I'm aware, there are no negative outcomes for the participants including me!. Perhaps we all have a better life expectation these days but eat and drink too much of the the wrong things [I'm very guilty, no question] and we are around much longer. There's plenty of radiation to worry about after Chernobyl and current events but perhaps not so much from electrical equipment??? Has anyone ever died from radiation as a result of serving in a Nuclear Submarine? Politicians are now racing to recommend these military, compact, safe and [ROLLS ROYCE] efficient power units. The late, great James Lovelock said he would be happy to have one in his garden, with the grandchildren present!

"Living Too Late " Mark E Smith The Fall [Dead at 60]

Re: How safe are our collections?
 

I think the first time I was really made aware of radioactivity in wartime instruments was when I went through the excellent radio / electronics shed at Amberley Working Museum (or chalk pits, as it was then). Part of the display was a mock-up of the interior of a WWII aircraft and I was surprised to notice that many of the dials had little radiation hazard warning symbols placed next to them.

Re: How safe are our collections?
 

Pitchblende (radium/uranium) was mined down here in Cornwall, principally at Wheal Trenwith Mine and South Terras Mine.

Lawrence.

Re: How safe are our collections?
 

There's a serious error in that article:

quote:
Mercury, which is poisonous, is used as a getter to absorb any remaining oxygen molecules in valves; this is what causes the internal silvering on some valves.
:end quote

It's usually Barium. Heated up Mercury would vapourise and have the opposite effect of a getter.

I wonder if that article has any bearing on the unhappy tales of very expensive valves being destroyed by a certain export shipping agent as "containing hazardous substances".

Re: How safe are our collections?
 

I think you have the wrong Richard if this was intended for me! At first I thought it was a PM wrongly pasted here!

Re: How safe are our collections?
 

Humble apologies Richard [FM]. That's the second time I've mixed the two of you up [geographically] It won't happen again:dunce: Anyway I hope my remarks about perceived risk still stand, although I don't have any direct history with radiation myself-only the asbestos episode I mention:(

Regards,

Dave W

Re: How safe are our collections?
 

Don't worry about it, I sometimes get the two Mikeys here confused.

Re: How safe are our collections?
 

Some tubes carry a radioactive marking on the box. That said, I went through the main gate of a military base with the back of my vehicle loaded with them and it never set off any radiation alarms they had at the gate.(I had forgotten those tubes were in the boxes). The radioactive material was used , IIRC, to stabilize the ignition point of many gas regulator tubes. I suspect I took more radiation from working on TV sets than the tubes or the paint.
I have several military sets missing meters because of the paint on the dial pointer.

I still have a can of florescent paint I bought from mil. surp. that will glow when exposed to light. Had that for more than 50 yrs now.

I don't worry much about it, as I am on limited time anyway.
They found my expiration date on the bottom of my left foot, but have not deciphered it yet.

Re: How safe are our collections?
 

Was thorium the radioactive material in the gas regulator tubes, or something else? Are valves like the 0A2 going to stop working eventually even if they're unused?