Electric cars are a pipe dream

[Billy T]

To kitemanSA:

You don´t seem to know that the Chernobyl reactor was carbon moderated. I.e. it had tons of carbon in it and thus a few pounds at the tips of control rod (if that is even true)* would not make any significant moderation for physics reasons I have already explained.

What really caused Chernobyl to become, by far, world´s worst nuclear disaster was that after pressure container was ruptured, the hot carbon moderator, then exposed to air, began to burn. If it had been designed for power production instead of plutonium production it would have been water moderated and not much worse than US´s "three mile island" (in Pa) disaster.

The purpose of Chernobyl reactor was to make plutonium which is easily separated chemically for A-bombs. (No expensive, power hungry, gaseous diffusion plant like Oak Ridge had is needed for chemical separation.) For same reason, N. Korea uses Plutonium bombs.

* I asked you for link supporting your "It ran away due to carbon tips on the control rods" story, but you gave none. I tried briefly to find any indication that the control rods even had carbon tips, but could not. That seemed highly improbable to me in part because they would not even function as the neutron absorbers** need for control rods and many other high temperature materials exist (including some high temperature ceramics containing boron) that would function as very effective control rods exist. I also find no evidence that a reactor with positive thermal coefficient switches to have a negative coefficient as you assert. Please back that up with a link too.

** Carbon is used as a moderator because it DOES NOT ABSORB NEUTRONS!

 

[KitemanSA]

Interesting; I was not aware of any LFTR that has ever produced power. (We were specifically talking about LFTR's, not the more generic MSR's.) Which facilities produced power?

A LFTR is a MSR that uses liquid fluorides and burns U233. The MSRE did both. Other that the trivial breeding component which has been demonstrated in the LESS efficient solid fuel form, the MSRE was a LFTR. It produced about 3 full power years worth of energy over a period of 5 years. Since it was a research reactor, that was damn good.

So were light water reactors. There were so many safety systems that there was no conceivable way to have a serious LOCA. At least in theory.

Yup, but all those systems were engineered system, not natural systems. The latest Gen III+ reactors are finally going to natural systems. The basic design for LFTRs has ALWAYS relied on natural systems.

Like I said, LFTR's are a great idea and should be researched further. But decades of real world experience will uncover problems that lab/prototype tests will not - which is why current LWR designs have a safety edge over more exotic designs. That may not always be true, of course.

I guess we will just have to agree to disagree, even though you are wrong!

It gives me one night; daytime production is high enough that even cloudy days allow operation of the basics (refrigeration and computers.)
Uh - OK. I guess I can live with unreliable power that is 100% reliable under my use cases.

Marvelous, and I thank you for it. I wish I was in a living situation that permitted me to do the same. But such is condo life. And while WE might be ok with that situation, it strikes me as totally unconscionable for the government to force others to participate. Solar and wind are, for a 24/7 technical civilization, still unreliable. They may not always be... but IMHO, that will depend on figuring out a low cost VERY high capacity energy storage system.
PS: I'm working on one.

 

[KitemanSA]

To kitemanSA:

You don´t seem to know that the Chernobyl reactor was carbon moderated. I.e. it had tons of carbon in it and thus a few pounds at the tips of control rod (if that is even true)* would not make any significant moderation for physics reasons I have already explained.

I am very aware that the RBMK design reactor is a graphite moderated design. Thank you for your insult.
It seems you are unaware of this nifty little compendium of information called Wikipedia. If you had been aware, you could have looked up "Chernobyl Disaster" and found the following segment.

A more significant flaw was in the design of the control rods that are inserted into the reactor to slow down the reaction. In the RBMK reactor design, the lower part of each control rod was made of graphite and was 1.3 meters shorter than necessary, and in the space beneath the rods were hollow channels filled with water. The upper part of the rod, the truly functional part that absorbs the neutrons and thereby halts the reaction, was made of boron carbide. With this design, when the rods are inserted into the reactor from the uppermost position, the graphite parts initially displace some water (which absorbs neutrons, as mentioned above), effectively causing less neutrons to be absorbed initially. Thus for the first few seconds of control rod activation, reactor power output is increased, rather than reduced as desired. This behavior is counter-intuitive and was not known to the reactor operators.

Let's have peace with the insults, ok?

 

[Billy T]

True most power plant reactors are designed for energy production, not A-bomb fuel production. US had one in Washington state, designed for bomb fuel production, and I think a few others. It is well known as it made a lot of local contamination but AFAIK, ...

Still doing that:

Leaky Tank at Hanford Nuclear Site ... A storage tank at the Hanford nuclear site in Washington state is leaking as much as 300 gallons of radioactive sludge a year, Governor Jay Inslee said, marking the latest setback in a decades-long clean-up effort. ... “This was a problem we thought was under control years ago,” said Inslee, who is to meet with Energy Secretary Steven Chu during a previously scheduled trip next week to Washington to discuss the progress in cleaning up Hanford. “I know this is a time of tight budgets, but with an active leak of high-level radioactive material into the environment, money can’t be an excuse for inaction.”

The leaky tank is among 177 stored underground at Hanford, a federal government site for radioactive waste generated by U.S. nuclear weapons production.

PS to KitemanSA: You are relatively new at Sciforums. I had no way to know your knowledge level, but now think it is high. Thus when you focused on the tiny bit of carbon at control rod tips, which can not even moderate the fast neutrons, as the cause of the disaster, I naturally wondered if you were unaware that the Chernobyl reactor had tons of carbon in it. No insult was intended by my asking if you knew that. When you know me better, you will understand that I rarely insult anyone. We are all ingnorant of some things. If it do give an insult it was well earned, and never just for being ignorant of something.

 

[Trippy]

Have you guys seen the McLaren P1?

Hybrid supercar: http://www.stuff.co.nz/motoring/shows/8332740/McLaren-P1-a-903hp-hybrid

 

[KilljoyKlown]

Have you guys seen the McLaren P1?

Hybrid supercar: http://www.stuff.co.nz/motoring/shows/8332740/McLaren-P1-a-903hp-hybrid

Interesting use of hybrid technology, but it only makes a car I can't afford more expensive and I'm sure the gas mileage hasn't really been improved much. However I would like to see it in a luxury model car.

 

[Syzygys]

"Tesla's Q4 2012 earnings: $90 million net loss, but forecasts a profit for Q1 2013"

 

[billvon]

Yup, but all those systems were engineered system, not natural systems. The latest Gen III+ reactors are finally going to natural systems. The basic design for LFTRs has ALWAYS relied on natural systems.

Sounds great! But as with every single awesome technology that has come along to replace the old unsafe technology, there are some gotchas that aren't apparent until it's in widespread service. We will have to climb that learning curve.

They may not always be... but IMHO, that will depend on figuring out a low cost VERY high capacity energy storage system.

http://en.wikipedia.org/wiki/Pumped-storage_hydroelectricity

 

[Trippy]

Do you have any link stating that? I´m pretty sure, if pressed, I could find links telling the operators were trying to measure the positive thermal coefficient of that design and had turned off the safety shut down systems etc. as I told before.

They were doing a saftey test. As you're no doubt aware, nuclear reactors require power to run their cooling system. The diesel backup generators that were in operation at the time took 90 secs (I think - may have been longer) to get up to full power after a loss of external power (Think Fukushima Daiichi). What they were wanting to test, as I recall, was whether or not the steam turbines had enough momentum to continue generating electricty to run the cooling systems. As part of doing this they took the reactor into a low power state, however, soviet RBMK reactors are notoriously unstable in low power states. This, however, was simply one step in a cascade of problems that led to the ultimate failure.

I also doubt that even if the contol rods had carbon tips...

They did, it's been well documented.

...they would do much moderation as they were thin with small transit distance thru them. Even water, which has much greater ability to remove energy...

And that was the problem. The final link in the cascade of failures. When the reactor scrammed, as the rods slid into place, the graphite which does not modeate the neutrons, displaced the water which does. power output spiked, the poisons in the reactor burned off, heat spiked, water flashed to steam, coolant pipes ruptured, and the rest, as they say, is history.

Thus I don´t believe even pure carbon control rods would make much moderations of neutrons.

Not the claim that was made.

Graphite was used as a displacer, not an absorber. The purpose of the displacer (if I have understood what I have read correctly) is to enhance the difference in neutron flux between channels that have control rods inserted, and channels that do not. Part of the problem at Chernobyl was the amount of time it took for the control rods to be inserted, the soviets took two steps to fix this after Chernobyl. The first step was they changed the way the control rods were cooled. At chernobyl, the control rods moved in water, which acted as a dampner, slowing down their movement. After Chernobyl, they filled the channel with gas for the control rods to move in, while cooling them with a thin layer of water. They also replaced the servos, to allow faster actuation.

Any more questions I can answer in relation to Chernobyl?

 

[Trippy]

I tried briefly to find any indication that the control rods even had carbon tips, but could not. That seemed highly improbable to me in part because they would not even function as the neutron absorbers** need for control rods and many other high temperature materials exist (including some high temperature ceramics containing boron) that would function as very effective control rods exist. I also find no evidence that a reactor with positive thermal coefficient switches to have a negative coefficient as you assert. Please back that up with a link too.

** Carbon is used as a moderator because it DOES NOT ABSORB NEUTRONS!

See my post - I'm quite happy to discuss Chernobyl at length.

 

[billvon]

the poisons in the reactor burned off

I think that was the biggest issue that led to the explosion. The xenon poisoning caused by the operator's mucking about with power levels resulted in a core that was nearly impossible to control. To run the test they wanted a higher level of reactivity, and with the xenon poisoning almost stopping the reaction that required all the control rods to be almost completely withdrawn. As the xenon burned off there were regions of the core that went to very high reactivity very quickly, and reinsertion of the control rods only made this worse as the graphite displaced liquid water in the core.

 

[Trippy]

At this point there were at least two unusual circumstances: The power level for the test was lower than planned and the margin of saftey, in terms of the ability to shut down the reactor with the control rods, was less than the normal operating limit. In addition, a number of saftey systems had been turned off to facilitate the planned test. In hindsight, it is clear that the test should have been terminated at this point, but it was continued.

Initiation and Progress of the Accident

As the test proceeded at low power, water flow conditions were not normal, there was some decrease in steam and the reduced reactivity caused automatic contnrol rods to withdraw to restore the reactivity. This was a manifestation of the fact that the Chernobyl reactor operated with a positive void coefficient.

This action was in itself harmless, but it raised the control rods to unusually high positions out of the vore. At 1:23:04AM. despite warning indications of the dangerous control tod configuration, the operators initiated the turbine test by shutting a valve and reducing steam flow through the turbine. The resulting changes in steam pressure and in water flow from the cooling water pumps led to a decreased water flow through the core and some boiling in the core. The displacement of water by steam caused the reactivity to rise.

In response at 1:23:40 am. an emergency shutdown (scram) was attempted. However, the control rods had been withdrawn too far to make immediate effect and, due to the graphite displacers at their ends, their first effect was to increase rather than decrease the reactivity. Within 3s there was a sharp increase in the neutron flux and the power output, as the reactor went superprompty critical.​

Nuclear Energy By David Bodansky (15.3: The Cherbobyl Accident)

 

[Trippy]

I think that was the biggest issue that led to the explosion. The xenon poisoning caused by the operator's mucking about with power levels resulted in a core that was nearly impossible to control. To run the test they wanted a higher level of reactivity, and with the xenon poisoning almost stopping the reaction that required all the control rods to be almost completely withdrawn. As the xenon burned off there were regions of the core that went to very high reactivity very quickly, and reinsertion of the control rods only made this worse as the graphite displaced liquid water in the core.

I seem to recall that there are indications that there was a sensor blindspot, but that there are (in hindsight) indications that a hotspot had builtup in that blindspot and that the formation of a hotspot in that part of the reactor was a known flaw.

 

[billvon]

I seem to recall that there are indications that there was a sensor blindspot, but that there are (in hindsight) indications that a hotspot had builtup in that blindspot and that the formation of a hotspot in that part of the reactor was a known flaw.

That may well be true - but at that point they were out of options; they could not prevent the runaway reaction. Even if they had halted control rod insertion, the burnup of the xenon would have led to higher reactivity, which would have led to boiloff (and thus voids) near the hotspot, which would in turn have led to a similar spike in power.

 

[Trippy]

That may well be true - but at that point they were out of options; they could not prevent the runaway reaction. Even if they had halted control rod insertion, the burnup of the xenon would have led to higher reactivity, which would have led to boiloff (and thus voids) near the hotspot, which would in turn have led to a similar spike in power.

Right, but if they had cancled the test, and not reduced the steam flow through the turbine, there would have been less (or no) boiling, and what happened might have been avoided - the displacers were only part of the problem, the boiling due to the reduced circulation rates was another. IMHO the biggest problem was the reactor design - even if from no other perspective than that of mixing superheated steam and red hot graphite being an inherently bad idea.

 

[Billy T]

Diesel

... A 1.6-litre turbodiesel delivers the torque surge of a much larger gasoline engine, yet with the fuel efficiency of a much smaller one. In the UK, diesel sales account for more than half of all cars sold, and even with a stat like that, Britain lags the rest of Europe, which has long preferred diesel to gas. So why would more Americans not drive diesels? ... Better mileage means fewer fill-ups, and the on-paper improvements in fuel economy would, overnight, take the US fleet one massive step toward President Obama’s targeted 54.5 mpg national average by 2025. Simply stated, diesel should “work” in the US. ...

Relative to a gasoline-burning engine, it is more difficult to control NOx in a diesel, which is why, to meet those comparatively stricter emissions limits, diesels in the US are required to use expensive, onboard after-treatment systems, which decrease the amount of particulate matter that leaves the tailpipe. Diesel engines are already more expensive to develop than gasoline units, given their turbos and complex injection systems. After-treatment systems make them even pricier. {but}

It’s worth it. Diesel used to be a dirty fuel and a dirty word, but recent technologies have addressed both problems, which is why the world outside the United States thinks of the choice between gasoline and diesel as a foregone conclusion. And even with the additional costs, passed on to the consumer, of emissions compliance equipment, the sensory pleasures of a diesel-powered vehicle are difficult to deny. It is high time, America, to give diesels a better look.

 

[billvon]

the sensory pleasures of a diesel-powered vehicle are difficult to deny.

Ah, but they're nothing compared to a pure electric. No shifting, no power pulses, no flywheel - nothing but smooth torque delivery (and recapture during braking.)

However, turbochargers as well as diesels are good intermediate steps. We're ramping up diesels rapidly here. We went from one available 5 years ago (Golf TDI) to 15 available in 2013.

 

[Billy T]

US gets much (50% ?) of its electric power from coal. The Norwegian University of Science and Technology study found greenhouse gas emissions rose dramatically if coal was used to produce the electricity {for electric cars}. Furthermore:

Electric car factories also emitted more toxic waste than conventional car factories, their report in the Journal of Industrial Ecology said. ... The production phase of electric vehicles proved substantially more environmentally intensive," the report said, comparing it to how petrol and diesel cars are made. "The global warming potential from electric vehicle production is about twice that of conventional vehicles."

In addition, producing batteries and electric motors requires a lot of toxic minerals such as nickel, copper and aluminium. {In their mining, etc. I think*} Hence, the acidification impact is much greater than that of conventional car production.

"Across the other impacts considered in the analysis including potential for effects related to acid rain, airborne particulate matter, smog, human toxicity, ecosystem toxicity and depletion of fossil fuel and mineral resources, electric vehicles consistently perform worse or on par with modern internal combustion engine vehicles, despite virtually zero direct emissions during operation," Hence, the acidification impact is much greater than that of conventional car production.

"Across the other impacts considered in the analysis including potential for effects related to acid rain, airborne particulate matter, smog, human toxicity, ecosystem toxicity and depletion of fossil fuel and mineral resources, electric vehicles consistently perform worse or on par with modern internal combustion engine vehicles, despite virtually zero direct emissions during operation,"

Neither electric nor diesel will dominate new car sales in the US in a decade or so - cheap CNG will. It drives most (95%) of the taxis in Sao Paulo, and a good fraction of the cars that can´t used alcohol even though it cost twice or more here than in the USA! Trucks and fleet vehicles are switching to NG and more stations have it now.

* Most of the power used for aluminum production is hydro-electric power but refining other materials may be more polluting. Making steel from iron ore, which from Brazil´s best deposits is nearly 93% pure Fe2O3, is mainly making CO2 pollution as hot carbon takes the the oxygen off the ore.

 

[billvon]

US gets much (50% ?) of its electric power from coal.

Not any more. Now it's 36% and dropping fast.

The Norwegian University of Science and Technology study found greenhouse gas emissions rose dramatically if coal was used to produce the electricity {for electric cars}.

Yes. But overall you still come out ahead. A DOE study a few years ago came up with the following CO2 emissions per year for cars (this was back when coal generated 50% of our electricity so they used that) -

EV 8000 lbs
PHEV 9000 lbs
HEV 8500 lbs
IC 13,000 lbs

Neither electric nor diesel will dominate new car sales in the US in a decade or so - cheap CNG will.

CNG will be one of the fuels we use, but use as a motor fuel will drive prices up rapidly and limit its penetration.

 

[Billy T]

... DOE study a few years ago came up with the following CO2 emissions per year for cars (this was back when coal generated 50% of our electricity so they used that) -

EV 8000 lbs
PHEV 9000 lbs
HEV 8500 lbs
IC 13,000 lbs

That is the in use advantage, considering only CO2 release. The Norwegian Study was a life cycle one, considering many other forms of pollution, even acid rain etc. EVs had double the IC engine car pollution in the making and disposal, so it would depend on how many years of use, without battery exchange, etc.

... CNG will be one of the fuels we use, but use as a motor fuel will drive prices up rapidly and limit its penetration.

Probably true, but it will depend, I think, on how many chemical plants are built in the US to make plastics, fertilizer, and other products from the Natural Gas, and to what extent, envirnomental consideration (especially water use and contamination) limit the growth of production of NG (and new pipelines needed).