Tepco carries out examination in Fukushima by remote-controlled probe | Hacker News Reader

Tepco carries out examination in Fukushima by remote-controlled probe

japantimes.co.jp

44 pointsUltramanoid34 comments

How fascinating that they might need to develop new tools for the unique circumstances. Does anyone know if they would keep the design proprietary and e.g. mine it for profits, or are they under any requirement for open-design, open process?

It strikes me that in what can be described as a "disaster" from many angles, they are potentially modeling a working containment-and-recovery process from other angles. This could be extremely valuable, the exception to the safety tradition that writes new rules providing higher leverage in working with beneficial and yet hazardous materials.

Tepco is not exactly famous for its competence. I understand the IAEA is involved at some level, though. I'd expect the latter to leverage any tech breakthroughs in this decades-long process and apply this knowledge to any incidents in the future, much as the air travel industry does, learning from every crash.

Custome tools are not unusual in nuclear cleanup. The Three Mile Island job required many very job-specific tools. This thing is a gripper at the end of a cable, built for the specific space into which it has to fit. The most it can do is take samples. Fuel removal is a long way off.

It's discouraging that it took eight years to reach this point.

It's been quite a few years and this is the first time they've made to reactor.

My guess is this success is not so much a matter of finally creating a clever design as it is the radiation has finally gotten down to a manageable level. I know they tried earlier with quite a variety of robots, all of which were rendered useless by the radiation levels (sensors and circuits becoming too unpredictable).

What are the radiation levels the failed robots experienced? Searching, I keep finding information about radiation levels in reference to human health. But I'm interested in the total dose those robots get before they fail. I used to work on space electronics that had to survive mega-rad levels of total dose radiation. How quickly do electronics accumulate those levels inside Fukushima?

Maybe I sound naive, but why do we need to move electronics there?.

Why they don't just use a disposable lead tube ending in the minimum working telescopic lens (mechanical) system possible and a cable moving electrons inside to build an image in a computer at km of distance. The brain of the robot should be out of the building, not inside.

Couldn't we estimate radiation by how long some well known matherial is surviving before to crash instead to use a sensor?.

Ah, the HN "why don't they just"...

A good overview: https://www.wired.com/story/fukushima-robot-cleanup/ containing the excellent phrase "Until we send the bot in, we don’t know what the conditions are. And after it’s sent, we can’t change it".

https://www.independent.co.uk/news/world/robots-fukushima-nu... : "The latest attempt to harvest data on Fukushima failed after a robot designed by Toshiba to withstand high radiation levels died five times faster than expected.

The robot was supposed to be able to cope with 73 sieverts of radiation, but the radiation level inside the reactor was recently recorded at 530 sieverts per hour."

If anybody is curious how much radiation a sievert is, there is a handy chart for reference:

https://xkcd.com/radiation/

530 sieverts/hour would mean a person exposed for less than a minute would be a dead man walking. Even a 30 second exposure would be difficult to recover from. Electronics would suffer from constant bit flips.

You would really need to keep most or all of the electronics back in a shielded box at the end of a long cable and make the robot as dumb as possible. This sadly only goes so far since you do need sensors that are made out of electronics on the robot. Cameras for example. It's a complicated system, and worse you need this robot to be quite capable if it's going to deal with uneven terrain and eventually breaking up and removing the melted fuel.

> a person exposed for less than a minute would be a dead man walking.

Yup, fortunately robots aren't alive

We know how to fabricate telezooms to take a photo to an animal at 400m distance. We use periscopes rutinely that do not need electronic necesarily. We know how to take a photo to the reflection in a mirror and zoom it later. We have the technology to make a mirror with a very finely polished metal surface (would be that sensible to radioactivity?), and we have all the time in the world to make a big photo secuentially from many small simple photos, ommatidium like. with less info encoded ...

Why we need electrons when we could use photons and an optic cable to translate the info at 100 km in some fractions of second? What happens with an optic cable when radioactivity hits it?

Optical materials of all kinds are vulnerable to darkening, clouding, and embrittlement by much lower levels of ionizing radiation than those in the reactor [1]. Darkening along the length of an optical fiber adds up quick, and will quickly render it opaque. Shielding won't help you at these radiation levels; you would need inches of lead cladding [2], and even then your fiber optics might not have a useful lifespan, exposed to at least tens of Sv/h along much of the length. And shielding offers nearly zero protection against neutron radiation.

Also note that the radiation in the reactor can heat the internal elements of your perisccope by hundreds of degrees, so without a cooling system your optical system's tolerances are at risk. Remember to make everything waterproof, and robust against shock and vibration.

After you figure all that out, you still need to get your periscope into the reactor somehow. Humans can't go closer than about a kilometer, and any robot you use must be able to navigate industrial wreckage.

These are not simple problems.

1 - http://www.dtic.mil/dtic/tr/fulltext/u2/a013786.pdf

2 - https://www.eichrom.com/wp-content/uploads/2018/01/gamma-ray...

"Virtually unusable after lengths of as little as 10m", wow. I'd no idea they were that vulnerable.

I don't expect being simple or they would had solved it in the last eight years, but exploring the idea further will not do much harm probably.

Stainless steel is waterproof and robust against shock and vibration so these points are solved yet.

The tolerance question is more problematic, steel can elevate their temperature to thousands of degrees without melting, but a mirror like that would suffer probably.

I ignore how darkening and clouding would affect in this case. Maybe the surface could be cleaned somehow?. Can we expect much embrittlement in metal?.

I suppose that would need to sacrifice at least one (or several) simpler robots just to put all the mirrors sync in place before to die. We would need need also a source of light, but spontaneous incandescence of a softer matherial should be easy to achieve.

At 530 sieverts (53,000 rads(gamma)) per hour mega-rad hard electronics could last about 18 hours. Long enough to do some work, but expensive if the robot could not be rennovated and they had to have an army of expendable robots. Such electronics have existed for quite a few years in the aerospace industry. Hard to come by and expensive for sure.

Well, that was a lesson on how crappy Google has gotten with historical, even recent historical data. All searches for Fukushima robots were events of the last two days. At least adding "2012" let me find some things.

Here's a very simple article on radiation hardening, which incidentally describes the danger to electronics.

https://spectrum.ieee.org/tech-talk/semiconductors/design/ra...

iRobots entered the main building in 2011. What happened just now is robot actually entered or surveyed the actual reactor vessel, in the building.

https://spectrum.ieee.org/automaton/robotics/industrial-robo...

https://www.google.com/search?q=fukushima+robots&tbs=cdr%3A1...

Limiting results to pre-2019/02/01 seems to go back to an article in 2017. Searching before that...

https://www.google.com/search?q=fukushima+robots&tbs=cdr%3A1...

... seems to pick up a good variety of articles going back to 2011.

Anyone know why it was raining inside the reactor?

seems that there is more progress on Mars than at Fukushima. That illustrates the true scale of risks/dangers/difficulty of dealing with nuclear disasters. Basically we have no technology to deal with nuclear disasters. All we can is just to wait for the radiation to decrease while for example in Belarus several thousand people die per year from Chernobyl related cancers (plus associated birth defects, etc.). And we can do nothing. This is why the only way we have is like Germany - getting rid of nuclear completely. While nuclear is our best bet in space, on Moon/Mars/etc., it just cant be used on Earth as we completely lack necessary technology.

At this point I'd rather take the risks and costs of nuclear instead of the sure problems of coal and gas. Until it is all replaced with renewable (hopefully very soon) we should definitely keep everything possible running.

To your point, the effect of Fukushima is two-fold in Japan. On top of the meltdown and its consequences, since most of its 50-odd nuclear plants were stopped with only half a dozen restarted since, and with Japan lagging quite a bit in renewable energy projects, most of the energy needs have been since then met with a substantial increase in coal and gas use.

I think it is important to remember that the number of nuclear-related deaths is unrivalled compared to the mortality from oil-related conflicts or mortality from coal pollution. Mortality per kilowatt for electrovoltaics is very high due to accidents during the installation of solar panels on roofs. Germany is certainly not a good model on this.

I expect that's true on a "per kilowatt-hour" basis.

BUT, the potential for harm from nuclear accidents is vastly higher, and also lasting (though one can make a competitive case for fossil fuel impact on global warming).

In any case, "the big one" hasn't happened yet. It may not ever happen, but if it does, ONE incident can cause incalculable harm.

I think potential for harm needs to be assessed in addition to just death per kilowatt hour.

No, it can't. This isn't magical technology; it has limits. The harm that can come from a single accident is constrained. Chernobyl and Fukushima represses pretty much the worst case, beyond what is even possible with better, more modern designs. Yet even in these cases the impact to human life is minimal when compared with other technologies, as noted by others.

While I understand where you're coming from, consider that there were initially hundreds of thousands displaced; tens of thousands still to this day. PTSD, depression, and profoundly disrupted lives. Many lost everything, and many will never return home. From this one incident.

Edit : I am specifically replying to the phrase "the impact to human life is minimal" when referring to Fukushima. I am not comparing harm of nuclear versus harm of fossil fuels, etc. Fukushima's consequences were, and still are now to a very large number of people, including displaced, farmers, fishermen, and even the effects on commerce and relations between Japan and neighbouring nations ( Taiwan's food ban, etc ), anything but minimal. How much cancer cases increased is not the relevant measure point here.

As opposed to the crippling health effects of fossil fuels? Fossil fuels are causing harm on a global scale orders of magnitude more than nuclear. And not just physical harm to humans, but ecological and economic harm as well.

Nuclear is by far the lesser of the two evils, providing baseload level amounts of carbon neutral energy with nearly a century lifespan, highly regulated and being far, far safer than any competing energy source.

I'm largely supportive of nuclear power, except for one problem: All new plants seem to require large public subsidies, both direct and indirect.

To get Hinkley Point C built, UK taxpayers have to guarantee an electricity price well above market rate, and the taxpayer has to underwrite all the loans, and the taxpayer will be on the hook for any accident cleanup costs above the reactor's $1bn insurance, and the taxpayer will be storing the waste, and guess who'll be paying for the decommissioning? That's right, in all probability it'll be the taxpayer.

In nuclear is the future, we're in for a very expensive future.

Are you under the impression that fossil fuels aren't similarly subsidised?

> While I understand where you're coming from, consider that there were initially hundreds of thousands displaced; tens of thousands still to this day. PTSD, depression, and profoundly disrupted lives. Many lost everything, and many will never return home. From this one incident.

This was in part (or, from what I read some time ago, mostly) caused by irrational fear and overrreaction to the incident, causing an evacuation much larger than necessary.

Well, there was definitely a bigger overreaction from foreigners living here, in fact. Thus the term fly-jin, thrown around quite a bit in those days. Pervasive PTSD and depression amongst the many thousands still displaced today ( specially the elderly ) is very real. There was an excellent article somewhere from a couple of years ago that I can't quite find right now.

    > Chernobyl and Fukushima represses pretty much the worst case...

No, they do not. Each of these could have been much worse.

And yet, even now people are still trying to piece together the scope of the damage that was done. These accidents were already incalculable in the harm they've done.

Both are examples of accidents which are physically impossible to happen on modern passively cooled designs.

That is a lie.

According to the WHO (https://www.who.int/ionizing_radiation/chernobyl/20110423_FA...), a "large fraction" of 6000 thyroid cancer cases (to 2005), of which 15 were fatal, are attributable to radiation exposure. No other health impacts are supported by evidence.

As such, the actual figure for deaths (at present, over 30 years since the incident) resulting from the Chernobyl incident is somewhere between zero and one per year.

Even if it was thousands of deaths per year (which it is not), that would still be far below the number of deaths caused by burning coal.

>As such, the actual figure for deaths (at present, over 30 years since the incident) resulting from the Chernobyl incident is somewhere between zero and one per year.

and that can't be farther from the Belarus reality. For example https://www.ncbi.nlm.nih.gov/pubmed/16506213

" In addition, a significant 2-fold increase in risk was observed, during the period 1997-2001, in the most contaminated districts (average cumulative dose of 40.0 mSv or more) compared with the least contaminated districts"

Breast cancer in general is the most frequent one - 1 in 8 women will get it over lifetime. Now double that. That is the reality of life in Gomel and Mogilev regions which took the brunt of the Chernobyl accident.

Russia and Ukraine have the same cancer rates, while Belarus - same people, same habits/lifestyle/etc. - have 1.5x cancer rates of Russia/Ukraine resulting in about 15000/year extra cases and the majority of those extra cases are in the Gomel and Mogilev regions. The cancer mortality in Belarus is 30%-50%. Do the math.

>According to the WHO (https://www.who.int/ionizing_radiation/chernobyl/20110423_FA...), a "large fraction" of 6000 thyroid cancer cases (to 2005), of which 15 were fatal, are attributable to radiation exposure. No other health impacts are supported by evidence.

that is a lie. The minimally honest WHO report would at least added something like this:

"There is a significant increase in cancer rates in the most contaminated districts. WHO sees no evidence connecting it to the contamination. Correlation is no causation. Pure random distribution. What are the chances!"

One thing that I try to keep in mind is that the quantity of energy that we're trying to extract from the natural world is orders of magnitude more than any animal has every tried before. There's going to be unexpected costs of wandering off nature's beaten path, whether it's radiation, airborne particulates, or runoff from PV manufacturing

For a beautiful illustration of this, I HIGHLY recommend:

https://www.stuartmcmillen.com/comic/energy-slaves/#page-1

Awesome comics, thanks!

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