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Compact nuclear fusion reactor is 'very likely to work,' studies suggest

nytimes.com

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Re: Compact nuclear fusion reactor is 'very likely to work,' studies suggest

#341

Post by Retric »

pfdietz wrote: post #295
fghorow wrote: post #165

Earlier quoted context omitted.

"Non Radioactive Fuel" is technically correct. But. The fusion produces neutrons.[1] That means that at least some parts of the infrastructure can't avoid becoming radioactive. Decommissioning -- at the very least -- is still a problem. Any actual nuclear physicists want to chime in here? [1]Yes, the concept of "Aneutronic fusion" exists: https://en.wikipedia.org/wiki/Aneutronic_fusion >. But read the parts about the…

Tritium is in the fuel, and it's quite radioactive. A 1 GW(e) reactor would burn enough tritium in a year that, if that quantity were to be released into the environment, it could contaminate 2 months worth of the flow of the Mississippi River above the legal limit for drinking water. Tritium containment at a fusion reactor will have to be damned near perfect. This will be a major problem, as tritium permeates throug…

Gaseous tritium being significantly lighter than air tends to end up in the upper atmosphere not contaminate the local environment. As it’s beta decay you could have a glass glass jar of the stuff on your desk for years without issue.

Unlike fission power plants there isn’t going to be years worth of the stuff on site. For one thing 5% of the stuff decays sitting around so you want a tight loop of production to consumption. Further, the reactor is holding low density plasma so there is very little inside at any one time.

Re: Compact nuclear fusion reactor is 'very likely to work,' studies suggest

#342

Post by notJim »

tuatoru wrote: post #283
notJim wrote: post #146

Earlier quoted context omitted.

I don't think that's quite an apt comparison. The fundamental physics of an atomic bomb were not well known until the late 1800s. Apparently the Manhattan Project cost about $23 billion in 2007 dollars. ITER apparently had an initial budget of around $5 billion in 2005-6. By now, the construction cost is estimated to be at least $22 billion. It seems plausible that if we throw $15 or 20 billion at it in 2006, we coul…

> The fundamental physics of an atomic bomb were not well known until the late 1800s. Er, don't you mean the early 20th century? Rutherford's exegesis of the nuclear model of the atom was published in 1911.[1] 1. https://en.wikipedia.org/wiki/Rutherford_model

Heh, wasn't sure where to draw the line. Radiation was discovered in the 1890s, so that seemed like as far back as you could go.

Re: Compact nuclear fusion reactor is 'very likely to work,' studies suggest

#343

Post by jasonwatkinspdx »

woeirua wrote: post #322
jasonwatkinspdx wrote: post #206

Earlier quoted context omitted.

This is a vast oversimplification, and not a particularly useful way of thinking about it. See my other brief comment: https://news.ycombinator.com/item?id=24634894

That's not a really good argument for continuing down this road. The US shuttered the large particle collider in Texas after it became apparent that it was going to be completely redundant with the LHC.

That's also mistaken. SSC would have placed tighter bounds on several measurements. The LHC is about more than just discovering the higgs as a binary yes/no.

Re: Compact nuclear fusion reactor is 'very likely to work,' studies suggest

#344

Post by Retric »

MagnumOpus wrote: post #316
Retric wrote: post #286

Earlier quoted context omitted.

Killing people is hardly the only issue. Rendering large tracts of land uninhabitable is extremely expensive. All told 4 nuclear reactors have had major issues, 2 subs and 1 power plant run by the USSR, and then another one very recently by Japan. Plus several near misses. That’s a significant percentage of total reactors ever built including what was considered a safe design. We could go 1000 years without another i…

> Rendering large tracts of land uninhabitable is extremely expensive Have you ever been near a coal ash pond? You probably haven't because it is an extreme health hazard to get anywhere near it, as it is full of mercury, arsenic, heavy metals and occasionally radioactive slurry. There about a thousand of these ponds in the US alone totaling maybe 100,000 acres. Meanwhile all the nuclear power plant waste ever produc…

Every nuclear accident was completely avoidable, but it’s not clear if future plant operators can avoid making similar mistakes.

The Chernobyl exclusion zone is 1,000 square miles. Fukushima had a much smaller exclusion zone but Estimates of radioactivity released ranged from 10–40%[163][164][165][166] of that of Chernobyl. The significantly contaminated area was 10[163]-12%[164] of that of Chernobyl.[163][167][168]

On 12 October 2012, TEPCO admitted for the first time that it had failed to take necessary measures for fear of inviting lawsuits or protests against its nuclear plants. That’s the core issue not physics.* ... A 2008 in-house study identified an immediate need to better protect the facility from flooding by seawater. This study mentioned the possibility of tsunami-waves up to 10.2 meters (33 ft). Headquarters officials insisted that such a risk was unrealistic and did not take the prediction seriously. The U.S. Nuclear Regulatory Commission warned of a risk of losing emergency power in 1991 (NUREG-1150) and NISA referred to that report in 2004, but took no action to mitigate the risk.[149] https://en.wikipedia.org/wiki/Fukushima_Daiichi_nuclear_disa...

France and the US have a solid nuclear track record, but so did Japan.

Re: Compact nuclear fusion reactor is 'very likely to work,' studies suggest

#345

Post by Obi_Juan_Kenobi »

RobertoG wrote: post #305
jnxx wrote: post #275

Earlier quoted context omitted.

Applied physicist here. The other thing is: Existing fusion concepts need to use a reaction between Deuterium and Tritium, otherwise it's just infeasible. Deuterium exists in nature and can be produced with some form of isotope separation. Tritium, however, does NOT exist in nature, and can only be conceivably produced in three ways: 1. Inside thermonuclear bombs 2. In heavy-water reactors, e.g. CANDU design, which r…

>> "Tritium, however, does NOT exist in nature" Maybe I don't understand properly, but I'm watching the video linked in a previous comment (1) and around the minute 9:30 professor White says that "what comes into the plant is actually deuterium and lithium". It seems he is saying that you need only an initial quantity of Tritium and then Helium and Lithium is used to created Tritium again. I suppose that it's what yo…

That's the breeding option, making tritium from lithium. Lithium can absorb a neutron and become helium and tritium.

Re: Compact nuclear fusion reactor is 'very likely to work,' studies suggest

#346

Post by pfdietz »

Retric wrote: post #341
pfdietz wrote: post #295

Earlier quoted context omitted.

Tritium is in the fuel, and it's quite radioactive. A 1 GW(e) reactor would burn enough tritium in a year that, if that quantity were to be released into the environment, it could contaminate 2 months worth of the flow of the Mississippi River above the legal limit for drinking water. Tritium containment at a fusion reactor will have to be damned near perfect. This will be a major problem, as tritium permeates throug…

Gaseous tritium being significantly lighter than air tends to end up in the upper atmosphere not contaminate the local environment. As it’s beta decay you could have a glass glass jar of the stuff on your desk for years without issue. Unlike fission power plants there isn’t going to be years worth of the stuff on site. For one thing 5% of the stuff decays sitting around so you want a tight loop of production to consu…

> Gaseous tritium being significantly lighter than air tends to end up in the upper atmosphere

That's not how it works. A low molecular weight gas anywhere below the homopause remains well-mixed, and does not separate by molecular weight. On Earth, that's anywhere below 100 km altitude.

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

Re: Compact nuclear fusion reactor is 'very likely to work,' studies suggest

#347

Post by maccam94 »

ivanb wrote: post #237
maccam94 wrote: post #214

Earlier quoted context omitted.

The SPARC design uses a combination of extremely high strength magnetic fields to contain charged particles inside the vacuum chamber and a molten-salt blanket (FLiBe) for neutron capture and cooling. They believe this will be a viable containment system.

And what do they do with gamma radiation? As I said at thermonuclear temperatures it contains majority of the energy of the system.

It is absorbed by the FLiBe salt blanket in the ARC design and converted to heat. The hot salt is circulated out and the heat is used for power generation before the salt is recirculated.

Re: Compact nuclear fusion reactor is 'very likely to work,' studies suggest

#348

Post by maccam94 »

splitrocket wrote: post #80

Fusion, always, always 5 years away for the past 20 years.

Up until 2005/2010 (the start of ITER), it was more like 30+ years away (ex: https://imgur.com/3vYLQmm ). 5 years is a while but 2025 has been the target for CFS for several years now.

Re: Compact nuclear fusion reactor is 'very likely to work,' studies suggest

#349

Post by dougabug »

bserge wrote: post #301
dougabug wrote: post #213

Earlier quoted context omitted.

But the tsunami didn’t render large areas of land uninhabitable, as in the case of Chernobyl and Fukushima.

The nuclear incidents didn't, either. Decontamination of Okuma has been successful and residents are already returning. Pripyat is an animal and vegetation haven. Really shows how dangerous our species is to the planet. Point is, nuclear power plants, even the old ones, are nowhere near as dangerous as the media portrays them.

The Chernobyl exclusion zone is 30km in radius. It’s not at all clear that serious effects do not extend beyond that, for instance to agricultural lands in Belarus.

Re: Compact nuclear fusion reactor is 'very likely to work,' studies suggest

#350

Post by Maursault »

ClumsyPilot wrote: post #262
Maursault wrote: post #220

Earlier quoted context omitted.

I'll respond to your straw man. It isn't about the energy within the thing, the exorbitant cost of Uranium is in mining and refining. No one said anything about coal, but it doesn't need refined, and is cheaply mined... but you've also made a false equivalency, because coal isn't the only competition to nuclear. The sun just shines, wind just blows, water just flows, and the geothermals just produce heat, without any…

Two questions: You keep repeating this idea thay uranium is expensive, by what metric? Where do you get the idea that its expensive? If nuclear is so expencive, why does France have cheapest elecrticity in EU? And Denmark /Germany have invested in renewables have expensive electricity.

Looks like I was simplifying. Uranium prices peaked around 2010 for $135/lb., and today is only $35/lb. The break even point for mining uranium is about $50/lb. So the problem in 2010 was that uranium was crazy expensive, but the problem today is it is so cheap, it can't be mined for profit.

But you raise a decent point about what metric we should choose... I meant the cost of the stuff, but there are other metrics, such as clean up costs, because mining uranium is not clean. There is also a human health cost to populations within the proximity of the uranium mine.

French electricity is likely cheap because the French tax payers already picked up the cost of constructing spent fuel storage facilities and power plant construction, and they will ultimately shoulder the burden of the cost of decommissioning. This is just an educated guess, because that is usually how nuclear economics work. Otherwise, the investors that run the plants and sell the electricity would not be interested.

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