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PostPosted: Jul 11, 2016 1:29 pm 
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Tim Meyer wrote:
So, you're talking SMRs ("standard" solid-fueled) for these icebreakers burning standard uranium. Maybe fluid-fueled isn't desired at sea? Dr. Eugene Wigner and Alvin Weinberg invented the LWR that led to Adm. Rickover's Nuclear Navy, Shippingport, and at last the present-day ossified solid-fueled global nuclear power industries with captured regulation.

I don't see how this topic is particularly relevant to energy from thorium that works in the solid phase but not as well as in the fluid phase. So how about the seniority of the thorium MSBR in regards to the Gen IV International Forum with respect to the U.S. DOE's 2016 "vision" for increasing nuclear capacity and their 2030, 2050, and 2070 milestones.

I see this announcement as applicable to thorium as an energy source since it shows a market for civilian small nuclear reactors. These may not be fluid thorium fueled when at sea because of certain limitations unique to such reactors but there is a lot of commonality which can be applied to fluid fueled reactors on land.

Tim Meyer wrote:
There you go, Mr. Sellner. From the great man himself! And it appears Argonne has had the upper hand over ORNL in DOE program prioritization ever since.

The comment on the DOE is quite telling. It shows that the problem of the DOE holding up research is a widely held belief by those in the industry. I have seen the DOE as a problem for a long time. It is quite rare for a problem to be solved by government, it is often that government is the problem. I recall a parallel in aircraft development, the government funded aircraft researchers produced nearly comical aircraft with laughable results. The privately funded Wright brothers did so much better, with much less funding.

I've said it before and I'll say it again, the DOE is holding up energy research more than it is helping. DOE has outlived its usefulness if we assume it was ever useful before. There are several ways to for the federal government to manage some of the regulatory matters that the DOE performs now should we choose to do away with the DOE. I've had people counter my claim to dissolve the DOE by pointing out some vital government services it performs but just because we do away with the DOE does not mean that those few vital services cannot be performed by the government, they just won't be under the umbrella of the DOE.

We had a functioning government and energy sector before the DOE, we can do it again after we do away with it.

A bit of a side note, I mention civilian uses of nuclear reactors in the context of icebreakers. Remember that the US Coast Guard is not a military establishment. They do have a highly military structure and function but they are not under the Department of Defense. The US Coast Guard is a Department of Homeland Security agency, and they were under the Department of Transportation before that. They are largely a police force, much like a state highway patrol but at sea. Civilian uses of nuclear reactors would therefore include US Coast Guard icebreakers.

Why is this civil/military distinction important? Because the DOD has a long history of having much greater freedom in the use of nuclear power than in the civil sector. If we continue to see people equate nuclear with military then we will continue to see nuclear power stagnate.

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PostPosted: Jul 18, 2016 7:45 pm 
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As near as I can tell, a small LFTR is a nearly ideal diesel replacement.
With appropriate materials it can run in the ANR temperature regime and power a once-through air turbine that doesn't need a low-temperature heat exchanger.
It would be economical in fuel, and have a high specific energy density, so the power plant would be compact.
The fluid fuel make it easy to clean the fuel up, avoid Xe poisoning.
Fluid fuels avoid hot spots, unlike solid fuels.
The marine version would need corrosion-resistant materials for the compressor's turbine.

Transatomic likewise is planning to get high specific energies. I don't think that they could run an air turbine, though.
The needed temperature is too high for the YLF corrosion barrier (melts at 819C) between their LiH moderator and LiF fuel solvent.
Still, it looks like it could be a small, lightweight reactor, and run a nice little steam plant.

The US NAVY isn't interested in fluid fuels. They've settled on small LWR steam plants for submarines and capital ships.
I actually think that those would be OK, too. The form factor and plant design are secret, but....
we know from mandatory accident reports that NAVY LWRs deionize radioactive water.
(Occasionally a sailor tries to discharge the ion-absorption resin into the wind, and gets exposed.)
So, they're almost certainly single-loop steam turbine plants with hands-on access to the loop, turbine,
and perhaps the reactor.
So, existing NAVY plants are very likely to use a combination of HEU and thorium.
They need HEU to power through Xenon poisoning in a compact reactor. (Imagine if a ship reactor couldn't start!)
They probably use thorium to get their very long core life, in a configuration
something like the one that they prototyped in Shippingport. (lasts 20 years or more.)
The use of HEU means that NAVY reactors are non-starters in civilian apps because of proliferation regulations.
(The regulations should change, but several people have said that those are the current regulations.)


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PostPosted: Jul 18, 2016 8:14 pm 
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This post is about the big Russian icebreaker.

Quote:
I have great confidence that the US Coast Guard will never find itself lacking a heavy icebreaker. What concerns me is that the US government might end up having to buy one instead of building one to our own high standards. The US government should not have to go shopping the world for icebreakers, it should be able to have enough funding and foresight to build them before they are needed in service.


Why not? Lots of jobs have been given away to other countries such as textiles, steel making, automotive manufacturing, etc. Why should a niche market such as nuclear icebreakers be any different? If Russia has risked its capital in investing in nuclear icebreakers shouldn't they be allowed to profit from that risk? Would it be more efficient for the US to repeat the learning curve that the Russians have already undertaken? Couldn't the US simply specify that a Russian built ship comply with expected standards? Why shouldn't they be allowed to succeed from their hard work whilst the US, bastion of free enterprise, has allowed it's own industrial base to wither?

By the way, this comment was made from the guy that thinks the government does a lot of good.


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PostPosted: Jul 19, 2016 2:45 pm 
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rgvandewalker wrote:
As near as I can tell, a small LFTR is a nearly ideal diesel replacement.


The problem is, what happens if the ship sinks in deep water? You end up with the entire source term dissolved in water.

Quote:
The US NAVY isn't interested in fluid fuels. They've settled on small LWR steam plants for submarines and capital ships.


How about a NuScale unit to power a larger ship. The largest container vessels and cruise ships use about 60MW

Quote:
The use of HEU means that NAVY reactors are non-starters in civilian apps because of proliferation regulations.
(The regulations should change, but several people have said that those are the current regulations.)


The use of molten salts would also fail the regulators.

One nice technology for ship borne reactors is lead cooled. I know the Alpha class subs had technical problems - some froze up - but in the event of a crash and water penetration, the fuel elements are encased in a protective cladding of solid lead. By the time that has dissolved (in the cold deep water) the fission products are decayed.


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PostPosted: Jul 22, 2016 9:05 am 
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Even without the liquid fuel, Th-20%LEU would be a good solid fuel for reactors. It has a high burn up due to U-233 created. It may need a change in a decade.


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PostPosted: Jul 31, 2016 5:31 pm 
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Eino wrote:
Lots of jobs have been given away to other countries such as textiles, steel making, automotive manufacturing, etc. Why should a niche market such as nuclear icebreakers be any different?

For the same reason that you don't hire Russian contractors to build your embassy. An icebreaker is a vital asset for assuring that commerce can traverse icy waters, as well as US Navy assets. The US Coast Guard does law enforcement, US Navy support, and other potentially sensitive missions.

Eino wrote:
If Russia has risked its capital in investing in nuclear icebreakers shouldn't they be allowed to profit from that risk?

They can profit from it but we are under no obligation to grant them that profit. Why can't the US compete in this market? Is not competition good for commerce?

Eino wrote:
Would it be more efficient for the US to repeat the learning curve that the Russians have already undertaken?

Perhaps we could send some of our shipbuilders to school in Russia. We can pay Russia for the lessons, that would be their profit. I suspect we have some technology they'd like to see, perhaps a technology trade?

Eino wrote:
Couldn't the US simply specify that a Russian built ship comply with expected standards? Why shouldn't they be allowed to succeed from their hard work whilst the US, bastion of free enterprise, has allowed it's own industrial base to wither?

What leverage would the US have to ensure that Russia does not sell us a sub-standard ship? It's not like getting a car off a lot, this would be a build to spec item, we can't just send it back to them and trade for another just like it. If the issue is that the USA has allowed its industrial base to wither then would not a competition for the best icebreaker be a good means to give it a kick start?

This is assuming that shipbuilding in the USA is somehow threatened, which I do not believe is the case. Quite the opposite really. It seems that the big shipyards in the USA are quite busy building ships for the US Navy, cruise lines, and cargo carriers. This is also assuming that Russia, or some other nation, has some sort of ability to build an icebreaker that would be superior to what we could build in the USA. As noted before Russia does not wish to build icebreakers that can operate outside the Arctic, which would be problematic for the US Coast Guard mission of supporting Antarctic assets. They obviously do have icebreakers that can operate in the Antarctic but they are not as large as what the Coast Guard seems to want.

Eino wrote:
By the way, this comment was made from the guy that thinks the government does a lot of good.

The government does do a lot of good, but it also has its problems. I take a warning about government seriously, that is often attributed to George Washington, government is like fire, it is a troublesome servant and a fearful master. This icebreaker problem is a good example of this. At one point we had three heavy icebreakers that were capable of Antarctic operations, but now we have one (the smallest) fully operational but quite old, one in port used as spare parts for the third, which is aging and with known operational problems.

A "good thing" that our government could do is order a couple new icebreakers, from a US shipyard, for the Coast Guard. Which is something they should have done a decade ago.

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PostPosted: Jul 31, 2016 6:05 pm 
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alexterrell wrote:
The problem is, what happens if the ship sinks in deep water? You end up with the entire source term dissolved in water.

I thought that the salts used in LFTR and similar reactors were not soluble in water.

alexterrell wrote:
How about a NuScale unit to power a larger ship. The largest container vessels and cruise ships use about 60MW

Arktika-class Russian icebreakers have two 171MW reactors. The Polar-class US icebreakers have 3x2.2MW diesel engines for cruising and 3x19MW gas turbines for icebreaking. Those two data points should give a better metric for a modern icebreaker power plant.

alexterrell wrote:
The use of molten salts would also fail the regulators.

One nice technology for ship borne reactors is lead cooled. I know the Alpha class subs had technical problems - some froze up - but in the event of a crash and water penetration, the fuel elements are encased in a protective cladding of solid lead. By the time that has dissolved (in the cold deep water) the fission products are decayed.


Given that LFTR is derived from a reactor that was intended to propel an aircraft I'd think that it'd be possible to produce a reactor suited to propel a surface ship. Also, would not the molten salt also perform like the lead in this situation? Perhaps even better? If sunk at sea the salts should solidify and contain any radioactive elements within it. The salts would not dissolve in the water any faster than the lead, right?

The problems of operating a LFTR or other MSR at sea is certainly not trivial but not unsolvable either. I believe we can make this work.

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PostPosted: Aug 01, 2016 5:31 am 
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I am still concerned about free surface effect in the reactor if you have any kind of cover gas system.
Unsecured highly dense liquids that can slop around is a nightmare for ship design
Would need lots of baffles in the reactor


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PostPosted: Aug 01, 2016 3:14 pm 
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According to Wikipedia, Beryllium fluoride is very soluble, Lithium Fluoride is soluble at 0.134 g/100 mL, sodium fluoride is soluble at 40.4 g/L, and in general "The solubility of fluorides varies greatly but tends to decrease as the charge on the metal ion increases." I am not a chemist but it would seem to me that the decay heat of the salt would cause vigorous mixing with seawater, and any insoluble fluorides would probably be dispersed as a suspension. So a shipwreck would be a very bad thing.

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PostPosted: Aug 01, 2016 3:25 pm 
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E Ireland wrote:
Unsecured highly dense liquids that can slop around is a nightmare for ship design.

Dr. Weinberg must have thought about this during the inception of the Naval reactor working with Adm. Rickover.

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PostPosted: Aug 01, 2016 6:29 pm 
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PWRs avoid this problem by being entirely filled with fluid.

And a steam generator has huge numbers of small tubes which act as baffles.
This only becomes a problem if you have a cover gas system, can that be practically eliminated in this design?


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PostPosted: Aug 03, 2016 10:28 pm 
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jagdish wrote:
I am sure the nuclear powered engines could cross the warm equatorial waters at slow speed using the warmer sea water. The Russians may not have felt any degradation in asking just in case.


I calculate a 12% drop in power using 30 C cooling water rather then using 0 C degree cooling water. Yamal would have 48MW of power rather then 55MW of power in the tropics.

This maybe a speed of 17 knots rather then 20 knots. Really, not that much different.


The Russians should not feel embarrassed at all for asking for help.


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PostPosted: Aug 04, 2016 1:26 pm 
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Wilson wrote:
jagdish wrote:
I am sure the nuclear powered engines could cross the warm equatorial waters at slow speed using the warmer sea water. The Russians may not have felt any degradation in asking just in case.


I calculate a 12% drop in power using 30 C cooling water rather then using 0 C degree cooling water. Yamal would have 48MW of power rather then 55MW of power in the tropics.

I've been surfing the internet a bit on this and I won't pretend I understand the details but it's not that simple. If it were that simple then the Russian heavy icebreakers would not be limited to the Arctic.

Wilson wrote:
This maybe a speed of 17 knots rather then 20 knots. Really, not that much different.

The relationship between power and speed for a ship is not linear, it's closer to quadratic. That would mean cutting power to 1/4 of maximum would mean a speed reduction to 1/2 from maximum. So, one might think that the warmer water would mean a speed reduction of only one knot. Again, I won't pretend I understand the problem but from what I read it was clear that unless an icebreaker was designed for tropical waters that leaving the Arctic cold waters would threaten permanent damage to the engines.

Wilson wrote:
The Russians should not feel embarrassed at all for asking for help.

Perhaps. I have to wonder if that incident of so many ships getting stuck and turned back by the ice didn't wake a few people up on how dependent we all are on a diminishing number of icebreakers for research, rescue, and commerce. Australia is building some new icebreakers, obviously Russia is as well, and it appears that some people in the US government are working hard to make sure we aren't left without a heavy icebreaker.

One interesting thing I found out is that it is illegal for the US Coast Guard to purchase ships that were not built in the USA. This can be waived by the president in extreme circumstances. What is also interesting is that it is rare for anyone to want an icebreaker that is capable of traveling in tropical waters, so very few shipyards are able to even build them. What is just as rare is the number of shipyards capable of building heavy icebreakers. If the US Coast Guard wants a warm water capable heavy icebreaker it appears it must be built in the USA or Canada.

While several nations are able to build heavy icebreakers, and several nations are capable of building warm water capable icebreakers, there appears to be a very short list of nations that can build heavy warm water capable icebreakers. Since the US has icebreakers to support assets in Arctic and Antarctic waters any icebreaker that is unable to travel in tropical waters would be of little value.

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PostPosted: Aug 04, 2016 3:17 pm 
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It has nothing to do with damaging anything. Just a loss of power do to thermo laws. The loss comes within the 4th loop cooling cycle of the reactor. You still have 48MW of minimum power to drive the propellers. Your saying that half to a quarter of its speed would be loss is incorrect. From 0 to 10 knots, it is not double or quadruple of power required to increase speed. But after around 10 knots, yes it is not linear but can reach quadruple if the ship was trying to do 17 knots. At 10 knots, you only need 20% power. At 17 knots, you need 80% power. The point is that the ship can make it to Antarctica. You can remove water from inside the hull to decrease drag, but I doubt this is required. You could move the water in the hull to the stern of the ship to reduce drag. Also, ships have a very hard time climbing out of the water at these low speeds and with this much weight. Therefore, you should have less drag at 17 knots then at 20 knots, not the other way around.

"Perhaps" No. The Russians do not have to feel embarrassed.


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PostPosted: Aug 04, 2016 9:22 pm 
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Wilson wrote:
Your saying that half to a quarter of its speed would be loss is incorrect.

That's not what I said, or at least not what I meant. I'll try again.

Drag, and therefore power required, increases with the square of the speed. If a ship can achieve a maximum speed of 16 knots with maximum engine output of 60MW then to steam at 8 knots would require only 15MW. If warmer waters required this ship to reduce engine power to about 45MW then it's speed would be about 14 knots. I'm saying you underestimated the speed possible. I believe that a better estimate would be 19 knots, not the 17 knots you computed.

I read an interview with a retired US Coast Guard icebreaker captain and he gave his own idea on why the Russians would never send any of their nuclear powered icebreakers to Antarctic waters. First lets address the warm water issue, he believed that their nuclear powered icebreakers were perfectly capable of operating in the warm waters but doing so is a big unknown. None of them were designed for such a task and doing so could cause unforeseen problems. One does not put a billion dollar asset to such a risk lightly. This is in contradiction to other things I've read from other people that know about such things where the claim was that doing so would have a very high probability of permanent damage. Where everything I've read agrees is that the warm waters are a risk to power plant damage, the disagreement was on how much of a risk it was.

Another issue this retired icebreaker captain pointed out is that tropical waters are known to be prone to storms with high waves. He spoke of broken windows on the bridge of his icebreaker from waves hitting it. Icebreakers by their nature cannot have the stabilizer fins under the water that most large warm water ships would have since the ice would tear them off. Unless an icebreaker has other means to counteract these waves there is a risk of being capsized in a storm. He did not elaborate on how USCG icebreakers managed this, only that they did.

Another issue is that Arctic ice is different than Antarctic ice. Russian icebreakers are made to break up ice that is more even than what is seen in the Antarctic. Something to do with ice coming off of land versus being formed at sea can mean much larger peaks will be seen in the Antarctic. Unless an icebreaker has the ability to quickly back up and ram the peaks it will not be very successful down south.

In the case of the Russian research icebreaker that was stuck there was the matter of logistics. This is a 20,000 mile round trip, during the Russian winter. They needed their icebreakers north. This is especially true since the icebound ship and crew were in no real danger, the icebound ship was a light icebreaker and strong enough to wait for the ice to melt. Once the passengers were off the ship there was enough food and fuel for the crew to wait it out.

That retired captain (I wish I would have remembered his name) also pointed out a political issue, some people might be upset with a nuclear powered vessel in their waters.

One thing pointed out in the Wikipedia article on the new Arktika is that temperatures on board could reach 50C (120F) if traveling in tropical waters.
https://en.wikipedia.org/wiki/Arktika_(2016_icebreaker)
I interpret that to mean that there is no air conditioning for the crew, and traveling for weeks with temperatures like that would be hazardous to their health. I estimate a roughly two weeks in warm waters for a one way trip if they can keep the Arktika at top speed. Since top speed could damage the power plant or kill the crew they'd have to spend much more time in very uncomfortable temperatures, risk capsizing if a storm pops up in that time, and then risk getting stuck in the ice themselves once they reach Antarctic waters.

I do not believe that it is too much of a stretch saying Russian nuclear powered icebreakers cannot reach Antarctic waters under their own power.

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