It seems Murphy’s law dogs every nuclear fusion experiment attempted. In the case of the National Ignition Facility, this time it’s problems with their tritium filters getting clogged by other particles. The options seem to be either letting the filters accumulate more tritium than had been anticipated before they are removed and taken to Nevada for disposal, or venting small amounts of tritium into the air. Obviously the residents of Livermore and the surrounding area would not be too happy with the latter option.
Doug Eddy, a scientist on the NIF project, is confident that ignition will happen next year.
NIF should serve well as a bomb code testing facility, which is what it was designed to do. The rest of it, LIFE etc and its undoubtedly earnest scientists, amounts to de facto greenwashing.
If inertial confinement can be made to work for a practical power plant the result will look almost exactly unlike the NIF.
I see it as more of a redemption story.
Regarding the NYT article, here’s a note from a friend who works at NIF:
Regarding the 4×10^14 neutrons – that is an accurate number. But it doesn’t actually tell you anything, since the fuel is diluted. The NIC campaign is currently “tuning the engine” to get to the point of ignition over the next year or so. This involves refining the details of the implosion using a wide spectrum of x-ray, neutron, charged particle and optical diagnostics. Up until the point of ignition, the neutron yield is (by definition) low by a few orders of magnitude compared to passing the threshold of ignition. The whole point about ignition is that it is a cliff-edge phenomenon.
One comment that leaped out at me:
“There is no safe level of exposure,” said Marylia Kelley, the group’s executive director.
I realise she’s from Tri-Valley Communities Against a Radioactive Environment, so I realise her agenda. However this kind of blanket statement suggests a lack of understanding of what the risks of radiation are, and the level of natural background radiation in our environment.
She would be receiving a far higher dose from the potassium naturally in her body, and the radon seeping up from the rocks under her feet than from any tritium emitted by the facility.
People often use the ‘Linear No Threshold’ model to extrapolate back from radiation effects at high & medium doses (ie Hiroshima & Nagasaki victims at various distances), to claim effects at low doses. But the statistics are very flimsy and the errorbars when you extrapolate that far mean you simply cannot say that that there is no safe level.
But if you cannot say there is no safe level, does that not mean that there is a safe level? What is it? Exposure below background is one thing, but going from there to saying low doses above background are safe because the statistics are flimsy seems like the wrong way around; if the statistics are flimsy we should not consider something to be safe. I’m thinking Fukushima and measured radiation “hot spots” outside the evacuation perimeter above background, that are considered “safe” because they happen to fall on a particular side of this flimsy fence. Perhaps, if all nuclear is replaced with aneutronic fusion, we will never need to know what the real safe level is.
I was thinking more on the lines that there are many areas of the world with much higher natural levels of radiation than would be permitted in the US or most countries if from man-made sources. There is no evidence that people living in these area are affected adversely in any way (such as higher cancer rates). Some studies even show beneficial effects.
risks appear to be, short-term and long-term. among short-term risks, there are: radiation burns, radiation sickness; among long-term, there is mutation, and cancer. safety is judged in terms of both acute and chronic exposure.
if the probability of increased risk due to exposure is below what we can measure, statistically, then government bureaucrats know that you will never be able to prove your cancer or birth defects were caused by chronic exposure. so they call it safe.
jamesr wrote: I was thinking more on the lines that there are many areas of the world with much higher natural levels of radiation than would be permitted in the US or most countries if from man-made sources. There is no evidence that people living in these area are affected adversely in any way (such as higher cancer rates). Some studies even show beneficial effects.
I have recently seen the reporting of beneficial effects misconstrued by popular TV commentators to be that scientists generally consider radiation exposure below radiation sickness levels to be beneficial; and that radiation risks are scare tactics used by politically motivated nuclear protesters. It is unfortunate that talk of these beneficial effects leads to people ignoring risks that are accepted by an overwhelming scientific consensus to occur at some exposure level.
Have people actually been exposed to unsafe levels of radiation from nuclear power? There are reports of radiation exposure hotspots outside of the Fukushima evacuation perimeter, including this one that amounts to hundreds of millisieverts a year:
Perhaps greenpeace is not the most acceptable source for this type of report, but the government reports exposure of many people to over tens of millisieverts a year; some exposures would be more concentrated than that. The permitted level is only 1mSv/year, which does not seem very relevant in this case.
I guess all this is off-topic from the NIF. However, it seems to me real risk of significant unsafe radiation exposure, as well as pollution from other sources such as coal power plants, is not acceptable and the world really needs something like aneutronic fusion.