Hacker News Reader

Comment by raverbashing | Hacker News Reader

"A critical report earlier this year by the Center for Public Integrity highlighted at a 2011 incident at LANL where eight plutonium rods were placed side-by-side for a celebratory photograph"

I am appalled by this. Professionals shouldn't be doing this

View on HN

The response to this should be to honestly discuss data about the risk and realistic case studies of previous accidents so that professionals actually want to act safely. I worked for three years at LANL (nothing nuclear), and the actual response will be to force everyone to watch an intellectually insulting video and take a quiz where all the answers are "check with my manager before I do anything", further fermenting a distain and distrust for procedure.

Unfortunately, the gut response "I am appalled; this must change" by folks who don't know anything about how the lab operates (i.e., lay citizens and politicians) exerts pressure toward the latter, not the former.

Agreed. And I also agree with treating these issues with more intelligence and less red tape

If you are handling plutonium and safety isn't an innate approach, then you shouldn't be handling anything more dangerous than bubble gum.

Nuclear material workers have much lower rates of job-related accidents and illness than many (probably most) other jobs. Much lower lifetime radiation doses than flight attendants, for example.

I've seen this happen in other industry (I'm thinking mining for ore).

The evidence was pretty solid that safety standards in the workplace are considerably higher than at home. Even relative to other industries performance was good.

This is only opinion, but I thought:

1) This was a good state to be in

2) It was bought on by ignorance of lay people and politicians who didn't understand relative risk

3) The situation reflected well on our political system functioning well without being very logical

It drives me crazy that we hold nuclear to a higher standard again even though the cost/benefit ratio appears to be better than many other industrial and non-industrial activities (eg, driving cars, using coal). People will cheerfully say 'but nuclear ... causes X', but rarely compare that with the benefits that were bought for X.

It's the sort of behaviour you'd expect from Homer Simpson

As an aside: Back in the day, I worked for a nuclear sciences consultancy whose hostnames for machines were Simpsons' characters. They strived to make control-systems fail-safe with extensive planning, processes safe as possible and simulations as accurate as computing power allowed (30 million lines of Fortan worth)... it just takes one nitwit thinking "it's okay" or "they 'know' better" to screw up the industry's reputation even more than prevailing NIMBYism.

It brings a certain logic to NIMBYism.

If anything can of course it'll be the bumbling incompetence of a nitwit that appears to do so.

Well the logic certainly isn't supported by data. Most homeowners have no problems allowing cars to drive around their neighborhoods, despite the fact that cars have dangerous emissions that kill thousands yearly, not to mention inattentive drivers who cause thousands of wrecks annually.

That's because it's their own cars. The same people will complain about a burn ban during a dry summer, because it's their own yard waste they want to burn. But you want to put a developmental group home in the neighborhood and they freak out. There's no sense to it, just egoism.

>I worked for a nuclear sciences consultancy whose hostnames for machines were Simpsons' characters.

I once tried giving hosts Arabic names. It actually worked pretty well since the naming system lets you express inheritance and works better when spoken than "proxy X on testnet Y" or "proxyX dot testnetY" (especially when not everyone speaks English as their first language and some people may be joining the call from a cell phone in a car).

https://en.wikipedia.org/wiki/Arabic_name#Example_name

I don't think it would scale to an IT larger than ~10 or so.

Neat, I had no idea that at a certain point, you're referred to by your relationship to your first-born son.

Does it only work better spoken, or does it also work better in written form? Do you include the article/prefix in the hostnames?

Naming is the most vexing aspect of programming, so you really must share more, even if just to deflate expectations.

Is this dangerous? Genuine question, it sounds like I should also be appalled but I don't know anything about plutonium.

Edit: Answered my own question:

> keeping bits of plutonium far apart is one of the bedrock rules that those working on the nuclear arsenal are supposed to follow to prevent workplace accidents. It’s Physics 101 for nuclear scientists, but has sometimes been ignored at Los Alamos

It's the most dangerous thing that can happen at a nuclear weapons facility. Too much plutonium in one place and it starts going critical. It doesn't explode, but lots of radiation comes out suddenly and people die of radiation poisoning. People have died from such incidents in the past.

Indeed, check out the infamous Demon Core:

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

Funny, that happened at los alamos again. That place really doesn't have a good record

That was 2 separate "demon core" incidents, about a year apart...so they clearly didn't learn much from the first one.

And at the time, Los Alamos was essentially the only place in the country -- probably the world -- doing that kind of research. So it's not really surprising that both incidents occurred there.

I don’t know for sure, but I thought I read somewhere it was called “tickling the dragon’s tail”?

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

> On May 21, 1946, physicist Louis Slotin and seven other Los Alamos personnel were in a Los Alamos laboratory conducting another experiment to verify the exact point at which a subcritical mass (core) of fissile material could be made critical by the positioning of neutron reflectors.

> It required the operator to place two half-spheres of beryllium (a neutron reflector) around the core to be tested and manually lower the top reflector over the core via a thumb hole on the top. As the reflectors were manually moved closer and farther away from each other, scintillation counters measured the relative activity from the core. Allowing them to close completely could result in the instantaneous formation of a critical mass and a lethal power excursion

> Under Slotin's unapproved protocol, the only thing preventing this was the blade of a standard straight screwdriver, manipulated by the scientist's other hand. Slotin, who was given to bravado, became the local expert, performing the test on almost a dozen occasions, often in his trademark blue jeans and cowboy boots, in front of a roomful of observers. Enrico Fermi reportedly told Slotin and others they would be "dead within a year" if they continued performing it. Scientists referred to this flirting with the possibility of a nuclear chain reaction as "tickling the dragon's tail", based on a remark by physicist Richard Feynman, who compared the experiments to "tickling the tail of a sleeping dragon".

An aside: It's this kind of shit that scares the crap out of me with regards to nuclear energy. Some - literal - cowboy completely disregards the rules, endangers him and his colleagues, and then someone gets injured or killed. All for the benefit of showing off.

We should do better than this, but incidents like this give me little faith.

Unsurprisingly, this experiment killed Slotin:

> On the day of the accident, Slotin's screwdriver slipped outward a fraction of an inch while he was lowering the top reflector, allowing the reflector to fall into place around the core.

> [Slotin] received a lethal dose of 1,000 rad (10 Gy) neutron and 114 rad (1.14 Gy) gamma radiation in under a second and died nine days later from acute radiation poisoning.

The picture of this is pretty indicative of the culture there. The room is a mess, they are handling the material with bare hands, and there's an empty glass coke bottle next to the apparatus. Given how toxic beryllium dust is, handling with bare hands and faces, and having a drink next to it, all of which seem to be asking for inhalation or ingestion. As for Slotin and the screwdriver, it beggars belief; why didn't they build a mechanism to raise and lower the hemisphere from a safe distance and within a shielded container? A simple hinge, and wire with counterweight would have allowed to to be carefully lowered and to "fail safe". It all seems a bit messy and haphazard, rather than the clean and organised environment we might hope such activities take place in.

When I look at the steps I used to go through multiple times a day when working in Cat 2 and Cat 3 biological containment facilities to work with cells and pathogens, including double door airlocks under negative pressure, safety hoods, protective gear etc., stringent aseptic practice LANL seems quite lax in their practices. We all watched ourselves and each other for bad technique and careless infractions to maintain that discipline without the need for dedicated separate safety inspectors (though periodic inspections did occur). That good practice was also tied into self-preservation of self and others when working with dangerous stuff; no one wants infection by some horrible pathogen. It seems quite bad to be working with even more lethally hazardous materials with basically zero protection, and the description of the attitude of the management 2011 and the present day towards safety seems to be equally cavalier.

In all the academic and industrial environments I've worked in, we had rigorous inventory and tracking of all dangerous materials (biological and radioactive), so it seems odd that LANL fails so badly here. This was the first casting in four years, and they immediately failed: why wasn't there preparation and planning for moving the material before the casting even started? Is Pu randomly stored around with place? Is there no oversight at all? In the lab I currently work in, we have to track every last trace of radioactivity (mainly P, N for biological labelling I think; I'm not involved directly) and account for it for statutory reporting every quarter, and if you fail to do it properly there would be a massive investigation and you would be banned from working with it; the lab managers make a bit deal of it, and rightly so.

It's a little ironic that safety has been compromised in order to meet production targets, but this resulted in a complete shutdown. Had they worked safely and sensibly and avoided the shutdowns, they would have overall been vastly more productive even if this was slower than the management would have liked. I've seen this pattern several times now in multiple places, from factories, to research laboratories to software development. It all comes down to unrealistic management goals from the top which dictate working at a fast place with attendant quality and safety problems no matter that a better end goal could be realised by working at a slower place with a little more care and thought. We see the same problem every time software design or implementation is compromised by a tight deadline with no scope for doing it the right way for the longer term, purely to meet some unimportant (in the greater scheme) short term deliverable.

The lab was created as part of the nation's balls-to-the-wall effort to build a nuclear bomb with which to smite its enemies in war. I imagine that safety was only a concern to the extent that incidents would slow them down. Otherwise, with thousands of people dying each day in the war, it's worth the risk to people at the labs if they can end the war faster.

Slotin got himself killed after the war was over, but it was less than a year after, and I imagine that sort of "get it done at any cost" culture does not change overnight.

I wonder if that attitude is in fact the root of the trouble today. Especially since I bet that the "save the nation and damn the risks" attitude came back for at least a decade or two once the Cold War ramped up.

I think you may well be correct in your assessment. Culture doesn't change overnight, and it's also inherited so may well have persisted to the present day. It also doesn't change without external pressure, and only reluctantly even then.

I've seen different cultures in various labs I've worked in or had contact with, and it can vary wildly from being extremely disciplined to extremely sloppy and both practices can be picked up by new people from the individuals concerned.

That was 71 years ago. A lot of things considered highly dangerous today weren't back then, and the dangers of radiation were also not as well known.

Upthread there are quotes from other physicists chiding Slotin because what he was doing was extremely dangerous. It was known at the time.

It was theorized at the time. Much of what we know about nuclear safety was learned from accidents like this. Slotin was doing excessively dangerous and downright stupid even for the time, but let’s still be careful to only judge him by the standards of the day.

Recreation of the criticality event in 1945 from the movie Fat Man and Little Boy, with John Cusack

https://www.youtube.com/watch?v=AQ0P7R9CfCY

"A Review of Criticality Accidents" (http://permalink.lanl.gov/object/tr?what=info:lanl-repo/lare...) provides a history of such incidents - an interesting, albeit quite shocking read! Quite ironically, the report was published by LANL.

By itself, per se, no. But I imagine when dealing with weapons grade plutonium you want belts and suspenders turned to eleven. So such breaches of protocols are indeed serious business.

Can't you store it inside a thick layer of lead?

Lead is a high-Z material, which provides a lot of electrons to interact with photons (and charged particles). It’s not good for stopping the neutrons that pose the danger here, because of the disparity in mass between the shield nuclei and the neutrons. For storing fissile materials in proximity, the optimal material is something with a high absorption cross section, like boron. Water and plastic are good at removing energy from neutrons and preventing leakage in typical large shielding scenarios, but in this case they would increase the danger, because they thermalize neutrons efficiently (as does a workers body) and this increases fission interaction probabilities and reduces the margin to criticality. For spent nuclear fuel, something like a boron-carbide plate is used. LANL may use something similar.

Indeed. The 2011 event was made worse by a worker using their hand to separate plutonium rods, which effectively placed a water barrier between them, making the likelihood of criticality higher. The link below describes the incident and how absurdly counterintuitive criticality safety can be.

http://www.sciencemag.org/news/2017/06/near-disaster-federal...

Yep! The mathematics is pretty simple and recurs in a bunch of other places, from the theory of evolution by natural selection, to the question of why things go viral on the Internet.

The basic idea is that these sorts of objects are routinely seeing spontaneous nuclear decays -- there might be billions per millisecond of these. What's important is that each nuclear decay is an explosion which releases debris that can cause other nearby nuclei to decay as a result. So it becomes important to know: what is the average number N of nuclei which fall apart as a direct result of getting hit by the shrapnel of one decaying nucleus?

Since nothing is terribly exact in physics there are two regimes to consider, N < 1 and N > 1. In that first regime we can roughly calculate that we need to multiply this baseline billions-per-millisecond rate of spontaneous decays by the number

    1 + N + N² + N³ + ... = 1/(1 - N)

The virality analogy is "Given one person shares it, what is the average number N of their friends who share it?" As you can see as this gets closer to N=1 it goes towards infinity.

For N > 1 the same multiplier holds but it cannot be summed infinitely: instead we realize that each term takes a slightly longer time period and thus the growth goes something like e^(k t) for some k, it's an exponential growth towards a majority of the sample reacting.

For fissile materials like plutonium, an easy way to increase N is to just bring two plutonium rods closer together: free debris from explosions in the one now cause new explosions in the other. This is called forming a "critical mass" hence the language about "criticality". Another way is to bring in these "neutron reflectors" that reflect the debris back into the same sample, it's basically the same principle.

If the critical mass of Pu-239 is 11 kg, can you go below that, say 5 kg, by reflecting the neutrons. I just wondering how much below that 11 kg you can go.

Is there a static substance that reflects loose neutrons? I thought that the choices for a substance were either to let the neutron pass through, or to absorb the neutron

Yes [1]. Beryllium is, I believe, the material of choice (although comes with its own problems, e.g. stupidly toxic dust)

[1] https://en.m.wikipedia.org/wiki/Neutron_reflector

If you're already working with plutonium, whose dust is also very, very toxic (in addition to being radioactive), the additional danger of beryllium doesn't seem so great in comparison.

I routinely handled beryllium for a couple of years as it is present in certain electronic RF power amplifiers. It’s perfectly safe in solid form. If you drill it or smash it, a different matter!

Plutonium, not so much.

I knew a software engineer who made a lot of money in a startup and bought himself an ultralight bike of titanium and beryllium. They ceased the beryllium parts at the Canadian border and I don't think he ever managed to get them released to him.

Beryllium's also used as a neutron multiplier.

I think only about 2% of the population is sensitive to beryllium. I was in a beryllium monitoring program (yearly blood tests) at work. A few coworkers are sensitive, one getting really sick.

Beryllium, amongst others.

google “demon core” for los alamos beryllium reflector hijinks gone awry.

I remember reading somewhere that water slows neutrons down enough to allow for a much lower critical mass.

I think it's in mentioned in Richard Feynman's account of his time in Loa Alamos in 'Surely you're joking Mr Feynman'.

Not just any water, only https://en.wikipedia.org/wiki/Heavy_water has that property.

Heavy water is more effective, but light (ordinary) water moderates neutrons too. That's how light water reactors work: https://en.wikipedia.org/wiki/Light-water_reactor

Moderators reflect and slow down neutrons so you get a controlled reaction: https://en.wikipedia.org/wiki/Neutron_moderator

Instagram mentality dies hard.

"What is this filter with the grainy effect? Oh wait..."

Im sure, the human stupidity will go away, if graciously wrapped with incident statistics and threads of repercussions. Or at least it will become unmeasurable- which to incident statistics comes down on the same side as safety.

Thank god for solar

It would make a great Snapchat location filter. The location of nuclear power stations, waste storage facilities and laboratories is basically static and well known. Those can be a little grainy. Three Mile Island, Fukishima and Chernobyl can be increasingly more grainy than the baseline.

"Nuclear is safe" - except for all the dumb things humans can do to cause a nuclear disaster.

Add up those dumb things and you still get less health risk or property damage than you get from coal dust or oil spills or gas explosions, which is why they correctly say nuclear is safer.

That's what happens when civil service gets politicized.

It is actually privatized in this case. Prisons, torture(interrogation), nukes ... I wonder could there be anything worse to privatize than those 3.

Reply on news.ycombinator.com