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Tokamak News and Queries

  1. Sep 26, 2016 #1


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    It appears that Stuart Prager is “stepping down” as director of PPPL. I wish him well.

    But in the announcement it refers to a “recent technical setback in the NSTX-U facility”.

    I had not heard previously of this set back and a short google search finds nothing.

    Can any one provide more information?

    Also I read various places that JET will run with DT in 2017 or 2018, but I can find no recent official schedule despite diligent searching. Does anyone know when they will fire up the machine and when they will switch to DT? https://www.euro-fusion.org/2015/06/jets-next-tritium-experiments-materialise/ this link seems to be the best I can find currently.

    Also does anyone have up-to-date information on the construction and operation of the ST40 tokamak by Tokamak Energy?
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  3. Sep 28, 2016 #2


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  4. Sep 28, 2016 #3


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    Seems life threatening for the NSTX-U and maybe for the PPPL as well. A problem at the heart of the machine, somewhat reminiscent of the magnet issue that held up the LHC for two years.
    The next Congress will have to decide whether to pony up the extra billion or so needed to get the effort back on track. If they decline that support, the entire lab may need to be restructured, as the NSXT-U was the centerpiece of the work there.
  5. Sep 28, 2016 #4
    After reading the article I'm not sure if the larger problem isn't political as opposed to technical.
  6. Sep 29, 2016 #5
    Seriously a billion dollars? Please be real!

    The cost of the entire NSTX upgrade was $94 million. This included a new center-stack, a new neutral beam injector, and numerous other upgrades.. The magnet that failed was not the center solenoid, I believe that it was one of the poloidal field coils. The cost to replace the coil is probably going to be a few million, possibly up to 10 million. But certainly nowhere near 1 billion dollars!
  7. Sep 29, 2016 #6


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    You may well be right, but the issue imho is not the direct cost of the parts that failed, it is the cost of keeping the lab up and running while it is perforce idle because its main machine is broken.
    Iirc, the lab budget is close to a half billion annually and I'm guessing a two year gap. I'd be thrilled if the reality turns out better, but cost underestimates have been a cancer on the fusion enterprise for as long as I can remember
  8. Sep 29, 2016 #7
    There's still a lot of discussion about JET doing a D-T campaign sometime in the near future, but as far as I know there are no official plans. At this point I think it's very unlikely that the campaign will happen in 2017.
  9. Sep 29, 2016 #8
    First, excluding ITER, the US magnetic fusion program has an annual budget that hovers between $400-500 million. The fusion budget as PPPL is going to a fraction of that.

    Second, while NSTX-U is the flag ship experiment an PPPL it is not their only experiment. There are numerous other experiments on site including LTX and MRX. Also many of the scientists at PPPL actively collaborate with numerous other experiments around the country and around world. Heck there's still tons of experimental data from pre upgrade NSTX that still has to be analyzed. It's not like the lab shuts down when NSTX-U isn't running.

    I'm not saying that the failure at NSTX-U is good. It's certainly a setback. And IMO the is the latest of series of failure by the PPPL engineering division.
  10. Sep 29, 2016 #9


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    At one point they were supposed to be running with plain ordinary hydrogen now, leading up to deuterium and tritium next year. Have they even restarted the plasma runs? I am pretty sure they are done building (or rebuilding) the beryllium and tungsten based "iter like wall" Woops, Google says they already did that in 2013. So what are they waiting for?
  11. Sep 29, 2016 #10


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    You are quite right, I'm mistaken on the numbers, the PPPL budget is in the $100MM class, a fifth of what I had believed, so the overall cost will be much less than what I expected.
    The offset is that the available funding is also much less than what I'd thought, so I think the crisis is no less real. I believe the fate of the PPPl is at risk and will depend on Congress' continued support despite this setback.
  12. Sep 29, 2016 #11
    Like I said, I don't know think there was ever an official date for DT operation.

    The truth is that D-T operation is very expensive. Tritium costs around $30,000 per gram. On top of that the machines going to radioactive once you out tritium in it. This is going to complicate all future maintenance and upgrades to the machine. So you don't want to put tritium in the device until you're absolutely ready for it. And ideally you want the machine to be at peak performance.

    If I recall correctly JET's performance has suffered some since they put in the ITER like walls. If this is the case then it's economical to hold off on the D-T campaign and to address the performance issues now. (This last part is speculation on my part).

    I also suspect that politics plays a role. In order to do they D-T campaign JET has to convince the powers that be that it's worth wild. And to be honest the powers that be are probably busy trying to figure out how JET and EUROfusion are going to survive Brexit.
  13. Sep 29, 2016 #12
    You're entitled to you're opinion. But I would imagine that the threat of closing down a DOE laboratory would draw a lot of media attention. There would certainly be congressional hearings and such. However, I first heard about the magnet failure over a month ago. (I think the failure occurred in late July). And Dr. Prager's stepping down is the only peep of the magnet's failure that I've seen in the news. At this point I've seen no evidence that suggests PPPL's future is at risk.
  14. Oct 4, 2016 #13
    Every JET 5-year program since 2000 has planned to perform experiments with 50-50 D-T fuel, but they have always been postponed. JET cannot even replicate the fusion results that it reported 20 years ago, which form much of the basis of projected ITER performance. This refusal to use fusion fuel has not stopped Culham director Cowley from proclaiming in one speech after another, year after year, that fusion power plants are about to take over the world’s energy supply! Fed up with JET non-performance and endless delay for tritium, European funding sources have forced Cowley to announce his imminent retirement.
  15. Oct 4, 2016 #14


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    Is not the problem that once JET starts using D-T fuel, it becomes quite radioactive?
    That would materially complicate any future research work done on the machine. So there is considerable merit in Cowley's approach, especially as ITER now looks to be a 2035 D-T first use program. There are lots of wrinkles still to be understood in managing plasma, JET is a good tool for that, so no point crippling it 20 years before the main machine is ready to pick up the slack.
  16. Oct 5, 2016 #15
    You are right about the reason why Crowley and the JET project do not want to use tritium. And there are two additional reasons:

    * The JET hierarchy is afraid that they cannot replicate the D-T results achieved 20 years ago.

    * JET no longer has the staff to deal with complicated and hazardous tritium systems, as the last tritium use was almost 20 years ago.

    But these three reasons for not using tritium are INEXCUSABLE and INDEFENSIBLE.

    Why? Because Crowley has spent the last ten years and more giving speeches proclaiming that JET was going to use tritium next year or the year after that, and exceed the results obtained in the 1990’s, and probably reach fusion gain Q > 1. [Google “Crowley JET fusion”]. Tritium use has been scheduled in every JET 5-year plan since 2000, and JET has been funded at $100 M per year in part because of the projected tritium experiments. If the JET project refuses to use tritium, then the project should return $1 billion to the taxpayers. As a compromise, Cowley has been forced to resign.

    Secondly, no fusion facility has been able to replicate the D-T results achieved by TFTR and JET in the 1990’s. The ability to replicate results is the very foundation of science, but JET is afraid even to make the attempt!

    Thirdly, the JET project has always claimed that they have the remote handling equipment able to deal with radioactive machine components. If that claim is false, then why should anyone believe that ITER can deal with activated components? Will the ITER staff also be afraid to use tritium for the same reasons feared by JET?

    -Donald Jasby
  17. Oct 7, 2016 #16


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    I would expect they can do a few shots with D+T. I would be very concerned if they could not replicate or surpass previous results, especially given apparent upgrades and what has been learned over the last 20 years. Not operating as intended, would be like taking a commercial power reactor critical, but not going to full power, and declaring success. Operating a reactor means material will get activated, and commercial reactors, and even research reactors, have to deal with it.

    In fusion reactors, even pure D-plasma (d+d) will generate neutrons.
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