OT- Portable Nuclear Power Plants

Hey Tom,

I can't say I follow exactly your equation, but here in Ontario we are in a race (apparently!!) to close the coal-fired power generation plants we have. This has become a hot political football, what with the Ontario Provincial election coming tomorrow. In any event, about your comment....Saturday I was at a fall fair a few miles from where we live, and near the fair there is one of the larger of the coal-fired plants that is under "attack". They had an information booth set up at the fair, mostly handing out literature about what a large scale employer they are, and the effect of loss of those jobs on closure of the plant; about how they are not as bad a polluter as they are ascribed to be, as they have some very late technology scrubbing equipment in place already and are willing to do more; and most important of all, the need for rapid and multitudinous changes of power required over the course of any 24 hour period (sometimes as high as 1500 change-orders per shift) and which nuclear plants at present are not able to modulate. This last item is what I'm writing about.

Nuclear power generation in land-based large plants is set to a "base level" of possible production. Nominally, this seems to me to be about 80%. In other words, a nuclear plant is ramped up from 0% to

80% over some period of many hours, if not of days, to this 80% level, and then continues to produce that much power (80% of its full capacity) regardless of the power usage requirement it is delivering to !! The load variation of off-peak to full-peak times is presently handled by the coal or gas fired plants. These plants are capable of rapid changes and of short term rapid dissipation of excess (steam) which the nuclear plants are not. Until the time when a viable method of either controlling the nuclear output or delivering excesses of it to either storage or conversion is standardized, the coal-fired plants are required.

But the day will undoubtedly come when that problem will be surmounted, and the coal-fired plants will be closed.

So, I asked the gentleman at the booth why not just build a nuclear steam generation unit alongside the coal fired plant, shut down the coal fired boilers and use the nuclear produced steam to operate the turbines? That way, we'd still have the generation capability in place where it is now. His answer was that, at the moment, all the nuclear plants in Ontario produce high volumes of steam at relatively low pressures and they run turbines at a 1200 RPM (no explanation as to why to either), whereas coal-fired plants produce steam at high pressure and rotate at 3600 RPM. So there is no compatibility.

Which is why I'm replying about the Russian portables. Who is going to set a "standard" for compatibility for their use? And will they require being able to float into position? Both questions are rhetorical of course!

Take care.

Brian Lawson, Bothwell, Ontario.

What the coal guy may not have explained is that the cost of fuel for nukes is around 2% of their operating cost, so it's no hardship to run them at high capacity all the time.

-- Ed Huntress

Hey again Ed,

You are correct, in that "costs" never came up in my chat with the guy. At all !! I have heard someplace that it is scary to compare the cost of establishing a nuclear plant to the cost of establishing a coal fired plant, even when the same manufacturing companies do both (Babcock-Wilcox et al).

But neither is your statement inclusive of all the points here. My point, or rather their point, (and hence my previous reply/question to the OP) is that the fuel "burning" plants have a great and fast flexibility, and the "nuclear" plants do not. Can one of these Russian inventions really BE used? The nuclear plants WILL produce at a relatively "fixed" rate, whether it is required or NOT (at least in short time terms). Hence, SCRAMing when that output consumption can not meet production on an instantaneous distribution or use basis.

In the pro/con debates going on here in Ontario, and I assume across Canada, one of the research thoughts being pursued would be for any instantaneous excess nuclear generation be used to immediately produce hydrogen, which can be stored and used at later time, thereby consuming the over-production and nullifying the present problem with this inflexible production (which is PART of what the coal-fired plants do now). Whether the hydrogen produced would be used in motor vehicles or other transportation, or even to replace the coal in thermal plants with a "cleaner" fire, was not discussed. But it is a starting point.

Personally, I hope that maybe you and I, or at least our children, will see the day when nuclear will produce electricity in quantity without steam as intermediary.

Take care.

Brian Lawson

That is not true. Nuclear reactors can modulate their output perfectly well. In fact, a pressurized water reactor (that is the most common type of reactor) changes power nearly automatically to match demand because of its negative temperature coefficient .

(Vaughn gets a far away look in his eyes) Back in my nuclear reactor operator days, I could watch power vary from (say) 10% to well over 50% and not touch a single control. Larger power changes just took a little bump of the control rod position.

Commercial nuclear reactors are operated near their full power capacity for economic reasons, not because they are not capable of being modulated.

Vaughn

Yup, the investment in a new nuke is huge. .

True enough, but I believe that nukes can be run at outputs greater than their load with no significant cost penalty. I'm a little rusty on this, but that's my recollection.

I'm sorry but I didn't read the whole thread, so I don't have a clue. All I can think of is, "From those wonderful folks who brought you Chernobyl."

I just hope we start building nukes in a big way. My personal feeling is that it's inevitable anyway, and it would be a huge benefit to the economies of many countries and to the environment.

You too, Brian.

-- Ed Huntress

I don't know if is a Russian concept or not, but it certainly is not a new concept. Some were built back in the 1950's for the US military. One was used in Antarctica for some ten years. (See below) As I recall, a prototype of one of these reactors had a grisly accident that left an operator skewered to the roof of the containment building by a control rod.

Vaughn

(From:

"The Army Nuclear Power Program" "The military considered the possibility of using nuclear power plants to generate alternate fuels almost 50 years ago and actively supported nuclear energy as a means of reducing logistics requirements for coal, oil, and gasoline. However, political, technical, and military considerations forced the closure of the program before a prototype could be built."

"The Army Corps of Engineers ran a Nuclear Power Program from 1952 until

1979, primarily to supply electric power in remote areas. Stationary nuclear reactors built at Fort Belvoir, Virginia, and Fort Greeley, Alaska, were operated successfully from the late 1950s to the early 1970s. Portable nuclear reactors also were operated at Sundance, Wyoming; Camp Century, Greenland; and McMurdo Sound in Antarctica. These small nuclear power plants provided electricity for remote military facilities and could be operated efficiently for long periods without refueling. The Army also considered using nuclear power plants overseas to provide uninterrupted power and defense support in the event that U.S. installations were cut off from their normal logistics supply lines. "

"In November 1963, an Army study submitted to the Department of Defense (DOD) proposed employing a military compact reactor (MCR) as the power source for a nuclear-powered energy depot, which was being considered as a means of producing synthetic fuels in a combat zone for use in military vehicles. MCR studies, which had begun in 1955, grew out of the Transportation Corps' interest in using nuclear energy to power heavy, overland cargo haulers in remote areas. These studies investigated various reactor and vehicle concepts, including a small liquid-metal-cooled reactor, but ultimately the concept proved impractical. "

Solves the problem of NIMBY, out of sight

History channel had a segment about that very incident, they interviewed some of survivors and rescue workers. As i recall it was a stuck control rod that caused the accident. They did show fotage of the plant after the accident and described finding a missing worker impailed by a control rod that blew out of the reactor and went threw the roof of the reactor building.

Best Regards Tom.

Hey Rich,

Not sure what you mean, but he "works" for Ontario Power Corporation. They operate all the plants, both nuclear and conventional fuel-fired. That's not to say that he isn't biased by where his home is, of course. But I doubt he would be slinging too much BS. He'd be more likely to lose his job doing that, than losing it by losing the plant.

Take care.

Brian Lawson, Bothwell, Ontario.

Test plan

During the daytime of April 25 1986, reactor 4 at [show location on an interactive map] 51°23?22.39?N, 30°05?56.93?E was scheduled to be shut down for maintenance. A decision was made to test the ability of the reactor's turbine generator to generate sufficient electricity to power the reactor's safety systems (in particular, the water pumps), in the event of a loss of external electric power. A RBMK-1000 reactor requires water to be continuously circulated through the core, as long as the nuclear fuel is present.

Chernobyl's reactors had a pair of backup diesel generators, but because there was a 40-second delay before they could attain full speed, the reactor was going to be used to spin up the reactor's turbine generator. Once at full speed, the turbine would be disconnected from the reactor and allowed to spin under its own rotational momentum. The aim of the test was to determine whether the turbines in the rundown phase could power the pumps while the generators were starting up. The test was previously successfully carried out on another unit (with all safety provisions active) with negative results ? the turbines did not generate sufficient power, but because additional improvements were made to reactor four's turbines, there was a need for another test.

Conditions prior to the accident

As conditions to run this test were prepared during the daytime of April

25, and the reactor electricity output had been gradually reduced to 50%, a regional power station unexpectedly went offline. The Kiev grid controller requested that the further reduction of output be postponed, as electricity was needed to satisfy the evening peak demand. The plant director agreed and postponed the test to comply. The ill-advised safety test was then left to be run by the night shift of the plant, a skeleton crew who would be working Reactor 4 that night and the early part of the next morning. This reactor crew had had little or no experience in nuclear power plants, many had been drafted in from coal powered plants and another had had a little experience with nuclear submarine power plants.[4]

At 11:00 p.m., April 25, the grid controller allowed the reactor shut-down to continue. The power output of reactor 4 was to be reduced from its nominal 3.2 GW thermal to 0.7?1.0 GW thermal in order to conduct the test at the prescribed lower level of power.[5] However, the new crew were unaware of the prior postponement of the reactor slowdown, and followed the original test protocol, which meant that the power level was decreased too rapidly. In this situation, the reactor produced more of the nuclear poison product xenon-135 (the xenon production rate:xenon loss rate ratio initially goes higher during a reactor power down), which dropped the power output to 30 MW thermal (approximately 5% of what was expected). The operators believed that the rapid fall in output was due to a malfunction in one of the automatic power regulators, not because of reactor poisoning. In order to increase the reactivity of the underpowered reactor (caused unknowingly by neutron absorption of excess xenon-135), automatic control rods were pulled out of the reactor beyond what is allowed under safety regulations.

Despite this breach, the reactor's power only increased to 200MW, still less than a third of the minimum required for the experiment. Despite this, the crew's management chose to continue the experiment. As part of the experiment, at 1:05 a.m. on April 26 the water pumps that were to be driven by the turbine generator were turned on; increasing the water flow beyond what is specified by safety regulations. The water flow increased at 1:19 a.m. ? since water also absorbs neutrons, this further increase in the water flow necessitated the removal of the manual control rods, producing a very precarious operating situation where coolant and xenon-135 was substituting some of the role of the control rods of the reactor.

Fatal experiment

At 1:23:04 the experiment began. The unstable state of the reactor was not reflected in any way on the control panel, and it did not appear that anyone in the reactor crew was fully aware of any danger. The steam to the turbines was shut off and, as the momentum of the turbine generator drove the water pumps, the water flow rate decreased, decreasing the absorption of neutrons by the coolant. The turbine was disconnected from the reactor, increasing the level of steam in the reactor core. As the coolant heated, pockets of steam formed voids in the coolant lines. Due to the RBMK reactor-type's large positive void coefficient, the steam bubbles increased the power of the reactor rapidly, and the reactor operation became progressively less stable and more dangerous. As the reaction continued, the excess xenon-135 was burnt up, increasing the number of neutrons available for fission. The prior removal of manual and automatic control rods had no substitute, leading to a runaway reaction.

At 1:23:40 the operators pressed the AZ-5 ("Rapid Emergency Defense 5") button that ordered a "SCRAM" ? a shutdown of the reactor, fully inserting all control rods, including the manual control rods that had been incautiously withdrawn earlier. It is unclear whether it was done as an emergency measure, or simply as a routine method of shutting down the reactor upon the completion of an experiment (the reactor was scheduled to be shut down for routine maintenance). It is usually suggested that the SCRAM was ordered as a response to the unexpected rapid power increase. On the other hand, Anatoly Dyatlov, deputy chief engineer at the nuclear station at the time of the accident, writes in his book:

Prior to 01:23:40, systems of centralized control ? didn't register any parameter changes that could justify the SCRAM. Commission ? gathered and analyzed large amount of materials and, as stated in its report, failed to determine the reason why the SCRAM was ordered. There was no need to look for the reason. The reactor was simply being shut down upon the completion of the experiment.[6]

The slow speed of the control rod insertion mechanism (18?20 seconds to complete), and the flawed rod design which initially reduces the amount of coolant present, meant that the SCRAM actually increased the reaction rate. At this point an energy spike occurred and some of the fuel rods began to fracture, placing fragments of the fuel rods in line with the control rod columns. The rods became stuck after being inserted only one-third of the way, and were therefore unable to stop the reaction. At this point nothing could be done to stop the disaster. By 1:23:47 the reactor jumped to around 30 GW, ten times the normal operational output. The fuel rods began to melt and the steam pressure rapidly increased, causing a large steam explosion. Generated steam traveled vertically along the rod channels in the reactor, displacing and destroying the reactor lid, rupturing the coolant tubes and then blowing a hole in the roof.[7] After part of the roof blew off, the inrush of oxygen, combined with the extremely high temperature of the reactor fuel and graphite moderator, sparked a graphite fire. This fire greatly contributed to the spread of radioactive material and the contamination of outlying areas.

Hey Vaughn,

Hmmmmm....so, I wonder...why we still have coal-fired plants, and why the latest plants built are coal-fired too? Just cost? Just time (to build)? Just disposal problems? Just politics? Or do you see an actual purpose for the coal-fired units, at least at present?

And just a question about your statement...

..."I could watch power vary from (say) 10% to well over 50%"

Are you saying a variation of 10% to 50% of full power, or 10 to 50% of say 80% baseline, was automatically controlled through NTC? Or would the cooling towers see a fair load shed? And would this power generation be at the suggested 1500 possible changes per shift? What am I, and apparently all the people that are debating this here in Ontario, missing?

Interesting stuff!!

Brian Lawson, Bothwell, Ontario.

Here is Texas we just narrowly averted a coal power disaster as the politicos seem to have been (temporarily) bought by the coal industry.

AIUI, they suddenly changes their considered opinion when the voters themselves (pesky things that they are) voiced a loud contrary opinion. Some foolishness about clean air, if you can believe that...

The squeemish should not watch Law and Sausages being created.

Richard

My thoughts upon reading the article are that it might be a good idea to have a few of these floating nuclear power plants built and ready to use should we ever need them in an emergency.

Best Regards Tom.

Agreed seems other parts of the world do not fear nuclear power, did a little googling for fun and was very surprised to find forgien investors are trying to buy several US uranium mines. From what i learned i see that other countries plan on increasing thier nuclear power generation and others wtih no current nuclear power plant plan on building new nuclear power plants. Looks like investors see an increasing need for nuclear fuel in the near future. The problem here in the US is the negative image created by people who dont know what thier talking about duped the public into unjustified fear of nuclear power. Until these fears are overcome i believe the rest of the world will continue to build nuclear power plants and we will be stuck paying high prices for electric power generated by fossil fuels. Keep us appraised of how this all works out in canada.

Best Regards Tom.

On Wed, 10 Oct 2007 01:17:06 -0700, with neither quill nor qualm, "azotic" quickly quoth:

Like for the day after the Big One hits California and everything east of the San Andreas Fault slips into the Atlantic? Yeah, the quake might have scrammed San Onofre...

I much prefer the small amount of nuke waste to the crap the coal fired plants put into the atmosphere. Hell, if we switched our power production mainly to nukes, we even could have met the Kyoto Protocol requirements with no other changes (not that the protocol would have done any good whatsoever.)

-- Ultimately, the only power to which man should aspire is that which he exercises over himself. -- Elie Wiesel

Your are correct sir. The question is how are we going to dispatch the nuclear boogyman thats been looming around for the last 30 years. Public opposition is going to be the biggest obsticle in building the next generation of nuclear power plants.

Best Regards Tom.

History channel had a program about the accident in which some of the workers that survived the accident gave thier account of what happened. Thank god we don't opperate our plants like the russians. As i recall from the program the person in charge had no training in the nuclear field at all and got his job thru political connections. Everybody interviewed claimed his lack knoweledge was the major cause of the situation they found themselves in. Its worth watching if they air the program in the future. Very detailed sequence of events and why they happened.

Best Regards Tom.

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Severe financial pressure will do it. A real threat of a shutoff from the Middle East and Argentina would surely do it.

A lot of people who have audiences are re-thinking nuclear power.

-- Ed Huntress

with the extremely high temperature of the reactor fuel and graphite moderator, sparked a graphite fire. This fire greatly contributed to the spread of radioactive material and the contamination of outlying areas.

Raising the specter of Chernobyl in any discussion of nuclear energy in the western world is to raise a "straw man" argument. The design and operation of the Chernobyl-type plants represents nothing short of a crime against humanity. Nothing of the sort would have been allowed anywhere in the western world. There is no point in raising the issue of Chernobyl unless your goal is to obfuscate.

We learned about the dangers of graphite moderated shortly after WW-II when the UK had a smaller version of the Chernobyl accident. (Google "Windscale accident" for an education) There is a reason why you don't normally see commercial power producing graphite moderated reactors.

Vaughn