Shipbucket

Wait, the Alfas used the BM-40A and the OK-550, not the BREST. BREST-300 is much newer and is scheduled to be built within the next few years.

Anyway, yes, this is starting to derail the thread a bit. The main thing I'm trying to figure out is whether or not a 21st-century LFR or pair of LFRs at sea is "doable" assuming the appropriate configuration, favorable regulatory framework, physical infrastructure, and an overall sensible, non-Soviet-style approach to designing and operating the reactor. It's mainly for an AU nation where I can flexible with these factors, and the power plants would be operated by trained personnel from a state or supranational agency (which has a partial stake in the vessels), not random mariners. I've also posed this question to a nuclear energy group I'm in, with a link to this thread. There's a wealth of knowledge and experience among that group's members, and I'm hoping they could shed some more light on the issue.

Setting the LFR question aside, I'm curious about the feasibility of the following configuration:

• Bridge, reactor, electrical turbines, and crew accommodations all located forward in the bow section to enable a clear view to the front and allow for maximal utilization of cargo space behind the superstructure
• Either traditional shafts driven by electric motors or azipods located aft propel the ship, eliminating concerns about shaft line length
• More or less common bow/superstructure section across variants; the hull behind this section can be configured as a container vessel, bulker, RORO, reefer, canship, etc.

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Look at your information again. I know them as SVBRs. Anyway you still have the heat problem and the inability to SCRAM the reactor, making it unsuitable for cargo or other non-military ships.

As for locating pilotage at the bow? Not a good idea.

Could the coolant issue be mitigated through the use of an electrical heating element connected to shore power or a large battery for emergencies? I know they used something like that to pump frozen fuel out of the drain tank of the MSRE at ORNL, and FliBe has a much higher melting point than LBE. That's the idea I had when I first envisioned using LFRs for surface vessels. I don't know, maybe that's dumb.

And why is forward pilotage a bad idea? I'm trying to get some constructive feedback, and you're being quite vague. That's the theme I'm noticing here. It's always "No, that won't work. No, you're wrong. No, that has problem X." There's no "Well you could mitigate X with solution Y, but that creates difficulty Z. How do you intend to deal with the cost of Z?" Which is what I'd expect on this forum. Given that I've already read up quite extensively on the advantages and disadvantages of different reactor types, I haven't really learned anything from your responses so far that I didn't already know.

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We have a few vessel in Norway with engine and wheelhouse, placed all forward in the bow, for example Ramform-ships. A nuclear ship would have an electric drive. So all you need aft is a couple of electric pods and it's equipment

This diagram gives fairly detailed layout data for small modular shipboard reactors
http://ars.els-cdn.com/content/image/1- ... 3-gr25.jpg
and
http://ars.els-cdn.com/content/image/1- ... 3-gr21.jpg
and found here
"Considerations on the potential use of Nuclear Small Modular Reactor (SMR) technology for merchant marine propulsion"
http://www.sciencedirect.com/science/ar ... 1813003843

1. No. Metal lumps would still cool and aggregate at the corners and turns in the piping. .
2. Size and viewing perspective. The modern ship is over 200 meters long and is still an aft control 2-d object. The ship is not small or forward control like a missile.
When someone comes up with a neat idea, it usually is not originally with him. Instead someone else has thought of it first. Then the person who has the neat idea has to find out why the person who had the original idea in the first place could not make a go of it, or what went wrong that makes them abandon the approach.

I gave you the Alfa example (or rather it was brought up and I explained specifically why and what went wrong). More on the Alfa in a moment.

Now I will explain why the USN experimented with electric final drives in surface ships post WW I and why they abandoned that approach in the mid 30s as well as why they did not adopt the large marine diesel as the Germans tried to do.

At first glance, one wonders why the diesel electric power train never made it into warships (and to a large extent, still hasn't). It, with a lot of research, is eminently doable by the 1920s. It offers several advantages over the steam turbine direct ration or geared transmission drives most 20th century warships used. What advantages?

Large transmission gears are difficult to cut. The French, Italians, English and Americans all have trouble with this technology when they adopt it. Everyone else including the Germans at first had to have it hired out and done by foreigners. Then there are the turbines themselves. This problem particularly bedevils the Americans until the Nevada class battleships. The British have it solved for a decade prior. With diesels and an electric final drive, you do not need a special backing turbine, or reverse gearing to go astern. Then there is fuel economy. Then there is the fact that you do not have to wait 30 to 40 minutes to bring your boilers up to temperature, or have large floodable compartments in the center of the ship, or the possible boiler explosion or turbine shear from one lucky hit. A diesel electric system can be distributed and it can be subdivided and compartmentalized. Great. So why not do it?

Simple. Electrical load distribution systems (Tesla, so America has a huge tech advantage) still are poorly understood in the 1920s. (Refer to South Dakota at Guadalcanal or Saratoga when she is torpedoed twice). One critical failure in circuit design or one bottleneck unforeseen (Apollo 13 comes to mind) and your vessel goes dead and you with it. Diesels are poorly understood. The Germans know more about diesels than anyone around WW I yet their U-boats had mechanical casualties about as often as one would expect from such immature tech. Scale that up to drive a cruiser? Finally, if one can get it to work as scaled up (German armored cruiser Deutschland) then one discovers no end of wear, tear, and unforeseen mechanical issues (mechanical vibration, hogging, hull warp, ventilation failure as in carbon monoxide poisoning in the lower compartments) so that kind of offsets the gee whiz factor. All of that which comes up operationally can be foreseen when one does a system operations analysis. Diesel electrics are out except for submarine use until about 1950 when MANN finally figures it out. They modularize the diesel as jacketed cylinder sets on an exposed sectioned crank so it can be parts swapped without tearing holes in a ship. Simple, but it took an intuitive genius to figure it out. Battle short for electric loads comes to the Americans in 1943, (South Dakota Lesson), so Apollo 13 is saved.

Now back to the Alfa. WHY would the Russians (I'm familiar with their rockets, so I know they are excellent idea to design engineers who have a tendency to overestimate the capacity of their materials science. The N-1 and N-2 did not fail because of the NK15. It failed because a systems operation analysis was not properly executed. Soviet constructors could not properly assemble or weld together a pump feed assembly for 30 rocket motors.) build such a sub with a lead bismuth eutectic moderator and first cycle heat fluid? They had to know the shortcomings of an LFR. They built two on land to test the reactor concept before they ever built a sub around it.

The best explanation for why they built the Alfa is that they needed some kind of bodyguard submarine for their missile launching subs which at the time they had to send out into the middle of the Atlantic because their missiles were short ranged. Their submariners had tangled with Permits using Novembers Echoes and Charlies. They were losing in the bump and scrape war badly. The Russian sub drivers wanted a smaller deeper diver and a faster more agile boat than a Charlie to have a chance against the Americans. Never mind that the sub drivers were wrong, it was the Gorshkov navy, full of nutty ideas that did not and do not work. What the boss wants, he gets.

The Russian engineers did not have a LWR system that could drive such a boat. They needed a small powerful steam plant. They knew that a sodium metal two cycle reactor did not work thanks to the Skipjacks. But there is this lead/bismuth eutectic reactor that might work. They built two types that they could install into a small ~2,700 ton boat. It was intended to be a dogfighter. This is obvious by the types of torpedoes it carried. It has been a colossal disappointing failure. The Alfa can still outdive any western boat and outrun the same, but it cannot avoid detection at all and it cannot outrun or outdive American torpedoes. Detected first, it is an easy kill. There are the additional reactor issues (see above) and it appears from news reports that the Alfas lack needed open ocean endurance, have crew habitability issues and have suffered extensive reactor casualties. Only 7 were ever known to be built. These things were actually losing to Sturgeons, that is how badly bungled the design concept from reactor chosen forward was.

Now as to the LFR reactor in a merchant ship? The question is "can an external heater melt the LB circulation cycle system once the reactor shuts down?" Probably not, no; make that definitely not because the Russians once they wharf an Alfa up, have to immediately put that thing on dockside power to keep the reactor heated and "hot". That sort of demonstrates in practice why the LFR is a commercial ship non-starter. The Russians cannot let the lead bismuth eutectic become a lump at all.

May I ask, Tobius.....
you said forward pilotage is not a good idea. somebody asks about this subject to explain further, as your reply gives no actual information. your reply to that talks about electric power conversion on ships, different kinds of reactors, tech in the 1920's, rocket motors and submarines. you do not mention forward pilotage at all, and your text does not contain any useful information to what you are quoting you are replying on.

maybe I am missing something, but that does not sound correct?

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Shipbucket Wiki admin

as for forward pilotage.
historically, the steering position is on the back of a ship, as close as possible (mechanical connections) to the rudder. most of the time, but Depending on the type and size of ships, the engines and everything to do with them are also aft. This meant that both the control of those engines and the crew required for them were needed mostly near the stern of the ships. seeing that the stern also has the advantage of overlooking the rest of the ship and being the part (with all the weight of the machinery and the streamlined shape to allow the propulsion to be efficient) where the least of the cargo could go, made the stern the clear choice for the steering position and the accommodations.

There are disadvantages to this though. amidships, the movements of the ship are the least, at the bow these are the roughest but at the stern they are neither. having your crew near your machines was good for maintenance and emergencies, but the accommodation suffered from the noise and vibrations of the machinery and propeller underneath it as well. In addition to this, the control position of the ship requires an good line of sight around the ship, especially in front. this meant that with the length and height of the ship, the pilothouse position has to go up with it, or be moved to an better position.

These 3 factors are the major points for where a pilothouse is placed on merchant ships. we see that RORO ships and passenger ships often have the pilothouse forward, because these want an superstructure as big as possible. we see the pilothouses being moved amidships on the biggest containerships, because the loss of containers from not being able to use the full height forward is less then the loss of cargo space under the superstructure. While most ships still are build with the superstructure aft because most of the jobs to do are done aft, there is no general requirement for superstructures to not be forward. on the contrary: as ships get computerised more and more, there are good points to move the crew away from the stern to get the cargo space more efficient. the penalty paid for that is more movement of the accommodation spaces. The ideal space for the crew would actually be amidships, if not for the fact that that is also the ideal space for cargo....... and cargo earns money, while crew costs money. It is clear why this is only done on the biggest ships.

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Drawings are credited with J.Scholtens
I ask of you to prove me wrong. Not say I am wrong, but prove it, because then I will have learned something new.
Shipbucket Wiki admin

HMM.

I suppose I need to explain forward control and aft control?

Take a long skinny object. Missile or ship, when it turns, you expect the shove forces employed to change the direction the nose/bow points alone?

When you apply yoking or shove forces at the nose of a missile to change its point at location in the future, the tail "kicks" or skids to one side in the turn. In a missile this is corrected by vectored thrust or pressure differential forces by tail fin steering vanes. To counter skid you need a view position or some way of seeing the tail as the missile turns. For missiles this was/is solved by telling the missile off platform (because it has to be updated dozens of times a second) where it was so it can point it where you want it to go by controlling its skid as you turn it; that is shove on its nose.

But a ship does not operate that way. It has a single set of underweigh controls, the rudder/screw set aft, so it is a pure tail control problem. Everyone who has ever sailed knows that is so, right? Not quite. Quite early, around 1830, the masters of sail who began to operate steam ships noticed on the faster steam vessels that when the ships turned hard under screws, they heeled over and the stern slipped (skidded) in the turn. The bow bit hard and held steady, while the aft end of the ship seemed to unstick in spite of the rudder (aft control). The USN called this "the kick". The shipmaster had to be in a place where he could see the length of the ship to gauge that turn and that kick. That turned out to be the middle and/or somewhere high for a large ship.

I mentioned (above) that viewing aspect is important for steerage control. Try it this way. Drive a standard car and you notice how you almost instinctively point the nose by sight lines on the hood in reference to some outside frame marker to keep the car under positive control. That is mid body steerage using nose control. Now climb into a truck where the cab has no engine hood to provide those sight lines. You are nose steer/nose control. Pull a trailer with it. Now you know why truckers use mirrors so much?

A 200 meter long ship may have bow steer/aft control, but not usually and that is because the complications to adapt the human to use it (different kind of training and mechanical setup) are usually not worth the hassle. Midbody or aft body steer from an elevated bridge is the usual solution for a large ship for a good reason. It is how WE operate as animals, not how the ship does as a machine that determines the best man/machine interface.

As for autopilots and computer steerage for ships, they still have to SEE. Radar will go where the sightlines for steerage are best; high above and not in the nose/bow.

This points out that it is helpful to see something of where the bow is pointing and where it is moving from the control position. To that, I agree.
However, just like in a car, there is no need for you to be all the way amidships for this. for example: the very long cargo ships on the great lakes often had bow control, but had a bowsprit rigged so they could watch this movement. The only case this is actually a problem, is when the control of the ship needs to be at the very front of the ship, without anything ahead of it. This is indeed an setup I have never seen used and which has other issues as well.

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Drawings are credited with J.Scholtens
I ask of you to prove me wrong. Not say I am wrong, but prove it, because then I will have learned something new.
Shipbucket Wiki admin