No. Fusion is pretty benign because it doesn't rely on a chain reaction. If containment breaks you get a non-functioning reactor, not a nuclear explosion. Some boom might happen because strong electromagnetic fields, coolants and hot stuff meet in the wrong ways, but that is all. There might also be some escape of short-lived isotopes like tritium. If it is a "dirty" reactor some parts of the casing will have been irradiated and will be radioactive, but the core is not particularly "hot". No doubt you can have nuclear accidents with fusion, but they are unlikely to be as nasty as fission accidents, where parts of the core may lie around still fissioning.

ITER it's not the only program that is working on nucleat fusion, we have a lot of works at about the same stage or better: -[url=http://en.wikipedia.org/wiki/Inertial_confinement_fusion]inertial confinement[/url] -[url=http://en.wikipedia.org/wiki/Z_machine]Z pinch[/url]a form of inertial confinement -[url=http://en.wikipedia.org/wiki/Focus_fusion]dense plasma fusion[/url] -[url=http://en.wikipedia.org/wiki/LENR]LENR (aka cold fusion)[/url] -[url=http://en.wikipedia.org/wiki/Bubble_fusion]sonofusion[/url] The first 3 have good background work and in some case (z machine) have reach hipotetical fusion temerature... LENR are less accepted but there are [url=http://lenr-canr.org/wordpress/]a lot of data[/url] that suggest this as a viable way, at best [url=http://pesn.com/2011/10/28/9501940_1_MW_E-Cat_Test_Successful/]near commercial[/url].... In EP universe all can coexixst used for different purpose: -magnetic (ITER), inertial and dense plasma use high temperature plasma wich make them useful as space drive and thermally efficient for power generation, radiation hazard are a drawback -LENR and sonofusion are of simple construction, have less rad hazards, seem capable of using H and D without use of He3 and can be scaled down, drawback seem low themperature (less efficiency for energy generation) and for LENR use heavy elements In my setting nuclear battery use a form of LERN for safety, i feel strange the use of radioactive elements for portable battery, even with good shielding the U needed for charge clip of a railgun in some hout seem enought for kill anithing biological with few minute of exposure. Alpha and Beta emitters are a lot inefficient as fuel for this purpose.

That 99% back reflection was impressive. I did not think any material could do it for x-rays.

athanasius wrote:

NewtonPulsifer wrote:

They were getting 99%+ with synthetic diamonds. With isotopically pure diamonds I bet you could get effectively 100%. That would make positron-electron annihilation antimatter batteries feasible too, as you could contain the generated high energy photon.

It's not true, they use a very low energy x-ray (20kv, medical use are from 45kv to 150kv) and consider for calculation reflected photons only, ionizing radiation have a lot of possible interaction and are very penetrating even at low energy.....

Check out the figure in the link again - or the paper here if you care to spend $32. http://www.nature.com/nphoton/journal/v5/n9/full/nphoton.2011.197.html Their dynamical calculations show that this reflectivity should hold up to 17.5[em]m[/em]eV, not just the keV range. And I wouldn't count out their theoretical calculations because it is what led these guys to this result in the first place. This wasn't an accidental discovery. And I'm confused about your point of "and consider for calculation reflected photons only". If one sees 99.5% reflection, by omission I've considered the other 0.5% - it didn't reflect. EDIT: Added the image in question [img]http://www.aps.anl.gov.nyud.net/Science/Highlights/Images/APS_SCIENCE_20...

One more thing about diamonds - isotopically enriched diamond to 99.999% of Carbon-12 is calculated to have a thermal conductivity of 200,000 (W·m−1·K−1) The only other thing in its range is ultracold superfluid Helium II below 2.2 Kelvin. The diamond would work at high temperatures. https://en.wikipedia.org/wiki/List_of_thermal_conductivities

Here's the Abstract (emphasis added) from http://www.nature.com/nphoton/journal/v5/n9/full/nphoton.2011.197.html "Ultrahigh-reflectance mirrors are essential optical elements of the most sophisticated optical instruments devised over the entire frequency spectrum. In the X-ray regime, super-polished mirrors with close to 100% reflectivity are routinely used at grazing angles of incidence. However, at large angles of incidence, and particularly at normal incidence, such high reflectivity has not yet been achieved. Here, we demonstrate by direct measurements that synthetic, nearly defect-free diamond crystals reflect more than 99% of hard X-ray photons backwards in Bragg diffraction, with a remarkably small variation in magnitude across the sample. This is a quantum leap in the largest reflectivity measured to date, which is at the limit of what is theoretically possible. This accomplishment is achieved under the most challenging conditions of normal incidence and with extremely hard X-ray photons." Put simply this is an x-ray mirror that goes up to the 17.5meV range that works at normal incidence angles. X-ray mirrors already existed before this experiment. Their problem is they only worked at shallow, "grazing" angles of incidence. This one works at normal incidence. That is, dead-on like a bathroom mirror. http://en.wikipedia.org/wiki/Reflectance Normal incidence: [img]http://www.liv.ac.uk/~darling/dynamica/off-norm/incidence4.gif[/img] EDIT: Check out the "Figures at a Glance" section at http://www.nature.com/nphoton/journal/v5/n9/full/nphoton.2011.197.html Second from the left shows a graph for 1meV photons: "a, Filled circles indicate relative reflectivity measurements. Solid line indicates dynamical theory calculations for a 1-mm-thick crystal and incident X-rays with a 1 meV bandwidth."

Just so I'm clear, you've gone from explaining I don't understand the experiment or the implications of it, to disputing the experimental results themselves? Are you also saying it is a physical impossibility to reflect hard x-rays and gamma rays?

athanasius wrote:

No, i have experience of reflected radiation but at high energy this is a very thin fraction of total photons, the biggest % simply are attenuated by matter or pass it.

So this following sentence from the abstract is a strange claim from your point of view? Near 100% is hardly a "thin fraction". "In the X-ray regime, super-polished mirrors with close to 100% reflectivity are routinely used at grazing angles of incidence. However, at large angles of incidence, and particularly at normal incidence, such high reflectivity has not yet been achieved." So you're claiming at grazing incidence x-ray mirrors can't achieve near 100% reflectivity? They can and they do. Every hear of a Göbel X-Ray Mirror? They achieve 10-80% reflectivity of x-rays at near normal incidence (not grazing). Hardly a "thin fraction". http://www.azom.com/article.aspx?ArticleID=741 http://en.wikipedia.org/wiki/X-ray_optics#Mirrors_for_X-ray_optics http://en.wikipedia.org/wiki/Nuclear_Spectroscopic_Telescope_Array http://en.wikipedia.org/wiki/Wolter_telescope And quoted from the last link "X-rays mirrors can be built, but only if the angle from the plane of reflection is very low (typically 10 arc-minutes to 2 degrees)." That quote is outdated, but essentially true of what was known say around 1994. This experiment involved a carefully constructed synthetic diamond and careful control of firing at certain atomic planes of the diamond formed in a plate. It's not the same as taking a round cut flawed and occluded natural diamond and doing x-ray crystallography on it. Near 100% reflectivity x-ray mirrors already do exist. A narrow degree limit means you need a large set of them to bounce a signal 180 degrees.NuSTAR has 133 mirrors in each of its optic units for this reason - and they work up to 79 keV x-ray photons (no idea of the lower limit). If you still don't believe in x-ray mirrors, then you can see a picture of them with your own eyes as part of the units that went in the NuSTAR x-ray telescope: http://www.nasa.gov/mission_pages/nustar/news/nustar20120530.html If the technology existed to make synthetic diamond mirrors that large, then yes, they could have made NuSTAR with just a few and not 133 per optical unit.