https://en.wikipedia.org/wiki/Natural_nuclear_fission_reacto...

> The natural nuclear reactor formed when a uranium-rich mineral deposit became inundated with groundwater, which could act as a moderator for the neutrons produced by nuclear fission. A chain reaction took place, producing heat that caused the groundwater to boil away; without a moderator that could slow the neutrons, however, the reaction slowed or stopped. The reactor thus had a negative void coefficient of reactivity, something employed as a safety mechanism in human-made light water reactors.

> After cooling of the mineral deposit, the water returned, and the reaction restarted, completing a full cycle every 3 hours. The fission reaction cycles continued for hundreds of thousands of years and ended when the ever-decreasing fissile materials, coupled with the build-up of neutron poisons, no longer could sustain a chain reaction.

What a wild story!

    approximately 1.7 billion years ago, during the Statherian period of the Paleoproterozoic, and continued for a few hundred thousand years, probably averaging less than 100 kW of thermal power during that time.

However the really amusing bit is that that everybody can agree--for different reasons--that:

> Here is a factoid: A factoid is a small fact.

Fortunately usage has consolidated. In my experience a factoid is generally intended to be true in (American?) English, but untrue in Swedish.

Nuclear Negligence (June 26, 2017)

https://apps.publicintegrity.org/nuclear-negligence/

    In the summer of 2011, Los Alamos National Laboratory presented a happy self-portrait to the public. 

    But that year something alarming happened at Los Alamos that the lab kept quiet.  A pair of workers with cavalier attitudes nearly doomed a room full of colleagues by stuffing so much plutonium into a small space that they came close to triggering an accidental nuclear chain reaction, all to get some photos.

Is there a specific variety the author knows that's toxic? ... Because this (manathakkali or "fragrant tomato") features in South Indian cuisine and is rather yummy.

> Atropa belladonna, commonly known as belladonna or deadly nightshade, is a toxic perennial herbaceous plant in the nightshade family Solanaceae

> The foliage and berries are extremely toxic when ingested, containing tropane alkaloids. These toxins include atropine, scopolamine, and hyoscyamine, which cause delirium and hallucinations

When I was a kid my Dad spotted it growing in my school grounds...

> Sometimes S. nigrum is confused for the more toxic deadly nightshade (Atropa belladonna)

[1] https://graydon.livejournal.com/186550.html

There was an interview with Jim Radcliffe recently in which he described Ineos’ approach to safety. It’s a variation on what’s described my Steven J. Spears in his case study of Alcoa. The truth is that the private sector has innovated much of what’s best in modern safety practice in a way that has made monumentally dangerous industrial processes routine.

There are perhaps good reasons to keep nuclear weapons management in the public sector. Canards about the safety record of the private sector are not though.

Yes, because of a mix government regulations forcing them to not cut too many corners for the sake of saving expenses, and people like the author of the article pushing back against higher-ups who try to do so anyway.

Let's not pretend that workers didn't die needlessly in factory fires a century ago because the factory owners locked the doors.

After scientists found what happened and saturation diving was theorised - companies kept their protocols of not decompressing when coming back, and kept killing their divers.

As a random example where a non-functioning judiciary resulted in a catastrophe, take a look at the 2020 Beirut port explosion, which a lot of people saw coming a mile off, but were unable to do anything about because of inept and corrupt judges that couldn't make a decision.

[0]: https://www.csb.gov/ U.S. Chemical Safety Board

https://www.youtube.com/@USCSB

I'm a little worried.

Eg. Y12 criticality incident - https://youtu.be/HaOc8FhMdWc

Nothing has changed since the times of Plutarch.

https://en.wikipedia.org/wiki/Shooting_the_messenger

How many people died of not just plutonium, but all criticality events? Less than 22, total (most of those Soviet). There is little reason to believe that even if these were household materials that they would be more dangerous than cars in the USA.

Handling highly radioactive materials serves no obvious immediate purpose and the dangers are very abstract until you get it wrong.

https://en.wikipedia.org/wiki/List_of_civilian_radiation_acc...

"People kill people, not guns".

You can kill me by throwing a person at me at 30mph; but it's easier to kill me by throwing a ton of iron at me at 30mph.

If you're right, then there are no driving accidents, and all injuries result from negligence or incompetence. In fact, the driving environment is so complex and chaotic that accidents are inevitable, even for the competent and attentive.

The vast majority of RTCs are indeed due to the inattention of a driver or not looking sufficiently (e.g. not taking care to move your head so that the A-pillar does not obstruct your view of pedestrians/cyclists etc).

I would consider accidental RTCs to be mainly due to either mechanical failures (which could be argued is due to lack of maintenance) or previously unknown medical issues.

It's interesting the difference in use of language between RTCs and shooting incidents. News reports will often make no mention of the driver and will make statements such as "car hits a building", but to use the same style with shootings would be risible e.g. "multiple bullets hit man resisting arrest". Of course, the car industry has been exerting control over media reporting of RTCs for about a century now, so it's very ingrained.

Perhaps I've misread you; you seem to be asserting what I said you were - that there are no accidents.

Also, why the passive voice? Who makes this recommendation?

[Edit]

> The vast majority of RTCs are indeed due to the inattention of a driver

Arguably, all RTCs are the result of inadequate attention from someone or other. But attentive, well-trained drivers have collisions too. Perhaps their attention lapsed? They're human - human attention wanders, they're not focused 24/7 on the task, because they're not machines.

Cars are all very well on roads that carry light traffic. But not many roads are like that nowadays: most driving environments are way too complicated for even an expert to negotiate completely safely.

There are too many cars.

I'd say most of them. It's possible to be driving along with a clear road ahead and have a person or object suddenly appear in front of you. I recall a case where a child was riding a bike on the pavement (sidewalk in the U.S.?) and for some reason lost control and fell into the road. The driver had been adhering to the speed limits and was paying attention but unfortunately was unable to stop in time and the child ended up dying.

There's lots of edge cases with driving which is why there's a bunch of recommendations regarding speed and leaving space so that when something unexpected happens, there's more chance for a careful driver to be able to stop or avoid the incident.

And yes, I totally agree about too many cars.

Pedantically (i.e. according to the Highway Code) the part reserved for pedestrians is the 'footway'; the part for carriages ('things with wheels', roughly) is the carriageway.

I suppose that between them they comprise the pavement.

I've taken to referring to them as carriageway and footway; it's unambiguous, and it even makes sense if you're shouting across the Great Pond.

Yes, it sounds stilted to me too.

Reporting recommendations:

https://www.forbes.com/sites/carltonreid/2021/05/17/its-cras...

https://road.cc/content/news/media-guidelines-launched-repor...

https://www.rc-rg.com/guidelines

Except that media use a different, equally bad construction. The so-called "cop-speak". <https://fair.org/home/copspeak-7-ways-journalists-use-police...>

Those aren't the same. A suspect is someone who has been charged, or who is being questioned under caution, because he might be charged. The example given was of a man arrested for possessing a knife - therefore a suspect - who was shot by police. Since a policeman shooting a civilian isn't usually charged or cautioned on the spot, it's not surprising that there is no suspect in the shooting case.

This is an incorrect perspective. If the same number of people as those driving cars had been playing with enriched uranium or plutonium, the casualties would have been much worse.

Google claims a total of 29 drivers have died during races, so the number of deaths in comparable, but I don't know how the total person-hours compare between NASCAR drivers and nuclear materials handling worldwide.

Did you not realise how ridiculous your comparison was?

The most important thing I took away from that experience is the concept of engineered compliance. People will break administrative rules and regulations all the time if they get int the way of work, so you need to engineer the physical system to account for that (e.g. flat or skinny geometry, or lots of neutron absorbers). This can apply to any compliance activity related to safety and security, so the lessons are universal.

Los Alamos published a good survey on various worldwide criticality accidents (PDF): https://www.nrc.gov/docs/ML0037/ML003731912.pdf. Worth a read for all the various ways things can go wrong.

The example I like to use is that the more paperwork you require for something like "obtain an internal use certificate for API endpoints" then the direct consequence will be less encryption of internal API endpoints.

Note that I didn't say "there may be", or "I predict that". No. It's a guaranteed consequence, like gradient descent making AIs better at meeting loss function. Except that it's gradient ascent, and you're making it steeper and expecting people to climb harder instead of just going around your pointless obstacle.

"More paperwork" -> "Less security"

"Less paperwork" -> "More security"

Choose.

These are things where cost center accounting just plainly hurts the company. (There are many cases where it works well and aligns incentives).

"Less paperwork" -> "More security"

That's almost an axiom in some circumstances but with criticality accidents there's a difference—first, the stakes don't get much higher, at close quarters death's a certainty and it's about as unpleasant as it gets; second, it's all over and irreversible in milliseconds.

There is no time to think, the body-brain reaction time is far too slow to take corrective action no matter how effective it may be when deployed.

That's different to giving consideration to a course of action based on the difficulty of obstacles in one's way—choosing the path of least resistance, etc.

The issues with that infamous photo are different, there was no obvious logical if decision to be made—it was all very straightforward, lay the Pu out and photograph it. The problems, however, are multifold: (a) those involved didn't have sufficient understanding of the possible consequences (of the physics involved), (b) they were poorly trained in safety procedures, and (c), the work environment wasn't 'engineered' to ensure compliance—that is, nothing stopped them from doing it.

As I pointed out in my post, training is crucial and it cannot be just theoretical. When the stakes are this high training has to be ingrained to such a degree that certain procedures are automatic, similarly, dangerous situations don't just become obvious after thinking about them, they are so the instant the brain responds. For instance, one recognizes the danger as quickly as one would if one tripped over a snake.

That's what the military does with training, one automatically reacts to a situation with the correct response without thinking. And that takes practice until one's perfect.

It works, it's a damn long time since I did any military training and I can stil carry out certain actions and procedures I learned decades ago and do so automatically and without a moment's thought. The people who set up and took those photos should have been trained to a similar level of discipline.

If actually enforced this way, then the next consequence is that people will use a credit card to spin their service up in some random cloud that you don’t control and won’t break.

… where all API endpoints are encrypted by default with zero paperwork required.

Get it? Forcing people to climb steeper slopes never ever works.

You need to make sure they fall into the pit of success even if they’re stumbling around in the dark with their eyes closed.

Years ago when I approached my first reading of the full accounts of Slotin and Daghlian I did so as with any other info, since then I have forced myself to reread them several times as a reminder—as both the accounts and photos are grim. They ought to be part of compulsory safety training for anyone vaguely associated with the nuclear game.

Perhaps, as part of that training there should be more acting out roles with dummy materials similar to military exercises where adjudicators tag one as dead for making a 'lethal' mistake and can play no further role in the exercise. This may seem trite but it's not, being forced to play dead on the battlefield whilst the exercise continues because of one's incompetence is both formative and embarrassing (I speak from experience).

Moreover, like military training, the exercises should be practiced until one's actions are automatic.

That said, such training ought to be a second-line defense—as fastneutron rightly points out—as such work environments ought to be engineered to force compliance.

Still, you're right it's a silvery gray metal much like many others that oxidizes quickly in air to give it that dullish look. If you were to pick it up you'd notice it's very dense. It's marginally heavier than gold by about 0.5g/cc^3 at about 19.8g/cc^3. That it looks so boring could easily generate complacency when handling it.

Edit: the 238 isotope is much more radioactive than 239, so much so it'd be hot to touch. But you'd be mad to do so.

https://en.wikipedia.org/wiki/Demon_core