Fusion power could arrive sooner than expected

Here's how combined fusion/fission plants would theoretically work:

A fusion reaction is used to create a large quantity of high-energy neutrons. These high-energy neutrons are then used to cause fission in an otherwise subcritical fission assembly with extremely low enrichment fuel. 'Natural' uranium (U-238) is fissionable, which means that it can undergo fission in the presence of /high energy/ neutrons.

I don't know all the ins and outs, but it's important to understand that the big US experiment in nuclear fusion was NIF, at LLNL. They (perhaps rashly) promised net energy gain by the end of this fiscal year. This whole thing was part of an elaborate political deal regarding maintaining nuclear expertise during the test ban treaty.

Anyway, net gain did not happen; the ratio of energy out to energy in at the NIF is 0.1. This had been expected for many months now (indeed, it was predicted by some as soon as the deal was cut, years ago.)

At this point, the pie of nuclear research dollars is going to be re-cut with different allocations. For one thing, the fusion/non-fusion balance at NIF is going to tilt away from fusion.

So, in the absence of a NIF fusion success story, this press release could be part of a campaign by other labs or other experiments to press their own research agenda for fusion.

For partial background:

http://www.nytimes.com/2012/09/30/science/fusion-project-fac...

Let me make it as clear as possible. Fusion energy is fundamentally safer and cleaner than fission energy, period. Firstly, it is simply not physically possible for fusion energy to generate even a tenth as much of the radioactive waste as an equivalent fission power plant. Secondly, it is not possible to have a dangerous power excursion at a fusion plant. When a fusion plant malfunctions it doesn't experience a runaway reaction, it stops working. If a fusion plant experiences some sort of catastrophic structural failure everything stops. This is in stark contrast to fission reactors which can undergo continued fission chain-reactions even if, and perhaps especially if, the reactor vessel is disrupted and the fuel melts down and also produce fission byproduct isotopes which continue to generate enough heat after the fission reactions have stopped to melt the reactor core if it is not continuously cooled.

Also, there is little evidence that the construction of a fusion reactor would entail a higher energy-usage footprint than a fission reactor, and the lack of a need for massive reinforced concrete structures in a fusion reactor tends to argue that the footprint would be rather less.

Let's roll it forward back to: undoubtedly cleaner if it can be made to work.