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After a week of limited coverage of "unimaginable levels" of radiation inside the remains of collapsed Unit 2 at Fukushima[...], Nuclear-News.net reported February 11 that radiation levels are actually significantly higher than "unimaginable".
Continuous, intense radiation at 530 sieverts an hour (4 sieverts is a lethal level), was widely reported in early February 2017--as if this were a new phenomenon. It's not. Three reactors at Fukushima melted down during the earthquake-tsunami disaster on March 3, 2011, and the meltdowns never stopped. Radiation levels have been out of control ever since. As Fairewinds Energy Education noted in an email February 10:
Although this robotic measurement just occurred, this high radiation reading was anticipated and has existed inside the damaged Unit 2 atomic reactor since the disaster began nearly 6 years ago.... As Fairewinds has said for 6 years, there are no easy solutions because groundwater is in direct contact with the nuclear corium (melted fuel) at Fukushima Daiichi.
What's new (and not very new, at that) is the official acknowledgment of the highest radiation levels yet measured there, by a factor of seven (the previously measured high was 73 sieverts an hour in 2012). The highest radiation level measured at Chernobyl was 300 sieverts an hour.
[...] This coverage relates only to Unit 2's melted reactor core. There is no reliable news of the condition of the melted reactor cores in two other units.
[...] Whatever is actually going on at Fukushima is not good, and has horrifying possibilities. It is little comfort to have the perpetrator of the catastrophe, TEPCO, in charge of fixing it, especially when the Japanese government is more an enabler of cover-up and denial than any kind of seeker of truth or protector of its people.
(Score: 1) by khallow on Wednesday February 22 2017, @06:45PM
Base load is a fundamental concept.
I disagree. Base load is a thing because not all power generation costs the same. You want to run power generation with the lowest marginal cost as much as possible and the most expensive power generation as little as possible. Most power generation can be run continuously. Thus, base load is the cheap power run continuously to maximize your return from it.
In MostCynical's hypothetical world of extremely cheap solar power and energy storage, the cheapest power no longer runs continuously and under good circumstances in hot climates, it comes much closer to mirroring the demand for electricity than base load would. Thus, the electricity infrastructure would be reoriented around that cheap intermittent power rather than around base load. The old base load might now become load following both to smooth out supply of electricity during darkness and to compensate when weather significantly reduces the output of the solar power.
(Score: 2) by jmorris on Thursday February 23 2017, @04:28AM
That isn't all of it. Another important distinction is base load is usually sources that can't be started and stopped quickly. Remember that the grid has zero storage, power generated must equal power consumed second by second or bad things happen. So for example a nuke plant is always base load since once you crank one up it takes a long time to cool it back down safely. Ok, you could just vent a lot of steam or something in an emergency but you don't normally want to be doing that. So nukes won't normally supply more than the nightly minimum load at any time. I doubt a hydro plant just starts and stops in response to transient load variations either. Natgas turbines are the currently preferred peak load source. That is why they like having many different sources of power. Too much of any unbalances the system though.
So an all solar grid is not happening, neither is an all wind, hydro or nuke. Unless they could actually make grid scale batteries ever work, then a lot of currently unthinkable scenarios become possible.
(Score: 2) by Aiwendil on Thursday February 23 2017, @07:56AM
Well, the EUR requirements for new builds are to go between 50% and 100% at the rate of 3% per minute (200 times per year), most GenIII are designed for 5% per minute or more
The mode french plants (GenII) are designed for is 30-85% within 30min (~2% per minute) unless at the start of very end of its current fuel cycle (so, only can manouver like this for 85% of the time).
In USA load following is only done with nuclear in Illinois (at least back in 2008).
If you are willing to risk damages to the fuel pretty much all BWRs can adjust at 10% per hour.
At the extreme end some unbuilt designs target 25% to 100% in 20 minutes (a cousin design is the EPR, so not a "far in the future" capability).
Depends on the reactor really, on well-designed reactors the limiting factors are condensers and max allowed discharge temperature of cooling water.
The Bruce reactors (CANDU 800MWe, each plant has slightly different features) can cool off up to 300MWe without adjusting core output (which it can do at 2.5% per minute). (The EC6 (Enhanched CANDU, 740MWe) is designed for a 100% steam bypass to condensers).
(Score: 2) by jmorris on Saturday February 25 2017, @02:26AM
Those are some nice features. Wish we could import some of that here, we really should be replacing every reactor older than thirty years, which is pretty much all of them that don't still have orange construction cones up.
(Score: 2) by Aiwendil on Saturday February 25 2017, @12:00PM
The CANDU reactors actually are old (excepting the EC6, which is a backport of CANDU9 features into CANDU6), heck, the bruce plant (2x4 reactors) went online between 1977 and 1987. And the CANDU6 are still the second newest member in the family (ACR and CANDU9 was shelved).
But quite frankly, nothing of the above is unique - most power reactors can go 60-90% at 2% per minite, it mainly is a regulatory issue.
The extreme degree of steam bypass in EC6 (it is a PHWR) can be acheived in all PWR reactors (steam is in the conventional part in those) with upgrades that would be bog standard with the exact same parts in other power plants - but would require a few shelves extra permits for some reason in nuclear plants.
Fun tidbit btw; excepting the CANDU (2x30yrs) most reactors was only intended to run for 30-35 years and go offline when their replacement went online (so we've ended up in a situation of where we run old nuclear reactors due to the people opposing the nuclear reactors) - good thing they overengineered them.
If you are interested in reading about reactors and what has been available since the 90s search for EC6, ABB BWR90, ABWR or Konvoi (that and the french N4 got mangled into the EPR).
Of the currently available reactors the EC6, ABWR, VVER/392M and VVER/491 are very interesting.
Or if you want to see what is right around the corner search for AHWR, HTR-PM, or ESBWR.
And a bit further into the future VVER-SCWR and CANDU-SCWR (CANDU-X) are bound to make quite a few go "wtf?!"