4 ms·

> Looking at how they worked with radioactive materials back then, it feels rather amazing that we're still here today. Nowadays, the dangers of exposure to ra

> Looking at how they worked with radioactive materials back then, it feels rather amazing that we're still here today. Nowadays, the dangers of exposure to radiation have been well publicised and I'd guess that most people over-estimate the dangers as plutonium can be handled quite safely (unless it goes critical of course). They used to regularly carry plutonium core halves in their lab coat pockets - one half either side of their body. From https://worksinprogress.co/issue/the-most-dangerous-substance-known-to-man https://worksinprogress.co/issue/the-most-dangerous-substanc... > Plutonium needs to be handled with care. You must avoid a critical mass. If you are machining or grinding plutonium as is required in reprocessing used nuclear fuel for solid-fuel reactors, you should avoid breathing the dust. But because it is a slowly decaying alpha emitter with very inefficient body uptake, it is one of the more easily handled toxic substances known to man. Our fear of plutonium is totally overblown.

A1kmm 3y ago
By my calculations, under some reasonable assumptions, the 'demon core' at the time was still a ~16.9 GBq alpha and gamma emitter when not undergoing a chain reaction (maybe more since its earlier criticality accident may have meant it had a higher proportion of shorter half-life elements). Calculation: Assuming 7% Pu240, 93% Pu239, (-(log 0.5 / (6560 * 365.25 * 24 * 3600)) * 6.02214076E23 / 240 * 0.07 -(log 0.5 / (24100 * 365.25 * 24 * 3600)) * 6.02214076E23 / 239 * 0.93) * 6.2 / 1E9 = 16.89 GBq. Admittedly, in the scheme of things, that's not that high, but criticality aside, handling it unshielded on a regular basis is not something that would be considered acceptable these days, especially not for a 'demonstration'. In 2023, when a 19 GBq sealed source (i.e. only slightly more activity) was lost in Western Australia when it fell from a truck, it sparked a massive search of a vast region, and the public were warned to keep a distance of 5 m. Obviously, they were worried someone would put it in a pocket or something for an extended period of time, and brief exposures wouldn't be that significant - but industrial radiographers working with similar sources, for example, would not get close to the source while it is unshielded and open.
- ndsipa_pomu 3y ago
  The amount of alpha radiation isn't a problem as that'll be stopped by a layer of skin etc. Plutonium mainly emits alpha with only a little gamma.

A1kmm 3y ago

By my calculations, under some reasonable assumptions, the 'demon core' at the time was still a ~16.9 GBq alpha and gamma emitter when not undergoing a chain reaction (maybe more since its earlier criticality accident may have meant it had a higher proportion of shorter half-life elements). Calculation: Assuming 7% Pu240, 93% Pu239, (-(log 0.5 / (6560 * 365.25 * 24 * 3600)) * 6.02214076E23 / 240 * 0.07 -(log 0.5 / (24100 * 365.25 * 24 * 3600)) * 6.02214076E23 / 239 * 0.93) * 6.2 / 1E9 = 16.89 GBq. Admittedly, in the scheme of things, that's not that high, but criticality aside, handling it unshielded on a regular basis is not something that would be considered acceptable these days, especially not for a 'demonstration'. In 2023, when a 19 GBq sealed source (i.e. only slightly more activity) was lost in Western Australia when it fell from a truck, it sparked a massive search of a vast region, and the public were warned to keep a distance of 5 m. Obviously, they were worried someone would put it in a pocket or something for an extended period of time, and brief exposures wouldn't be that significant - but industrial radiographers working with similar sources, for example, would not get close to the source while it is unshielded and open.

ndsipa_pomu 3y ago
The amount of alpha radiation isn't a problem as that'll be stopped by a layer of skin etc. Plutonium mainly emits alpha with only a little gamma.