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CaptLincoln

Nuclear Power: An Incomplete Guide

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Friends, in the modern world, we have many different forms of power production. Global warming is promoted with Coal. Oil leaks into the fields of North Dakota, and fought over in the hills of the Middle East. Yet there remains one form that the navies of the world continue to develop, despite widespread fear of the results of a disaster. I am, of course, talking about Nuclear Power.

Over the years, Nuclear Power has been the principle production method for several new classes of large, modern warships, from Frigates, prowling the seas with specialized armament, to Cruisers, armed to the brim with support weapons, to the Carriers they protect, launching the warplanes to take down the ever-constant threat of the Nuclear Submarine, stealthily infiltrating the task force to deliver it's torpedo payload with deadly effect.

Many in the world fear the consequences of continued nuclear development. Millions recall with fear the deadly radiation clouds of Chernobyl and Fukishima(Apologize for spelling). Countless more have stared in horror at the devastating effects that one Little Boy had on Hiroshima, and the horrifying results of Fat Man on Nagasaki. It is true, in the brief history of Nuclear Power in the vast book of naval legacy that there have been many catastrophic events on land involving nuclear power, however, this fails to consider the effects that Nuclear Power has had at sea. The purpose of this thread is to update it over time to eventually contain the full understanding of Nuclear implications in the world of naval affairs. As such, until that day comes, which in my honest opinion should be never, this guide will remain incomplete. Starting in the 1940's, we will look at the history of nuclear naval development, and as we reach the present day will endeavor to explain how it functions, and will end with what the future may hold for humanity's navies in the world of the atom.

Before we begin, it should be noted that this is going to be missing quite a lot. The original copy of the thread was missing a lot more than just what you see here, as it was simply from my knowledge, and was built upon over time by the comments and replies from the community. It is the goal to have the community help verify and expand this guide so that a comprehensive description of the modern navy may exist. And with that, full steam ahead!

It's December 2nd, 1942. Countless scientists stand ready to react to the slightest sign of error under the bleachers of Stagg Field. A pile is the focus of their attention as they await the news to see if their baby could actually function in the world of reality, and not their own vivid imaginations. This experiment, come to be known as Chicago Pile-1, is the world's first nuclear reactor. Although primitive and unable to harness the energy it produced, it proved that sustained nuclear reactions were possible. Three years later, at Trinity Test Site in the New Mexico desert, the world's first atomic bomb was detonated, spreading ash and debris for hundreds of miles, the flash seen as far away as Las Vegas, Nevada. These land-based developments would become the foundation of the modern nuclear force of the United States. Before we begin launching missiles, however, let's look four thousand miles east, in the waters of the Pacific Ocean...

The Pacific Fleet, the pride of the United States Navy, has been fighting the Japanese for months. Thankfully, their carrier production has gone through the roof, and now has the upper hand against the enemy. Carriers had gone from being simple take off platforms to full scale airports on the water, able to refuel entire squadrons in an hour. These carriers had only two weaknesses: They were large, flat targets for enemy bombers, and secondly, they had to refuel. A lot. Refueling at sea is a dangerous operation, when the tanker and carrier must be connected for a long period of time, leaving both especially vulnerable to attack. This gets the U.S. Navy to thinking: Is there a better way?

(If there are people out there with more information on this subject for the years after this, please post it below! I would love to give you credit in future renditions of this thread! I simply have little information myself about the history of the development)

Nowadays, the United States Navy has a demand for nuclear propulsion officers and enlisted, alike. Particularly, the Navy has founded the Nuclear Propulsion Officer Candidates Program(NuPOC) to help fill the void in the force. Training involves tours of reactors, Nuke School, and training at one of the two prototype reactors on land before deployment overseas as the Engineering Officer of the Watch.

The history of the reactor propulsion system is all well and good, but how exactly does it work? Nuclear reactors come in various forms, and many materials are available to describe Breeder reactors and other types, but for the stripped down, basic version of how reactors work: The reactor itself, contained in a thick shield to prevent radiation leakage, contains fuel cells, made up of what tend to be pellets of the fuel. Often the fuel is Uranium, however other elements are available to be consumed. The reaction, once started, is controlled by "heavy water," a chemical isotope of regular water with more neutrons that slows the particles released by fissioning atoms down enough so that they may hit other uranium atoms, and by control rods, which absorb excess neutrons. These rods can be raised and lowered depending on the circumstances to control the rate of the reaction.

Heat is generated by the reactor, which is used to turn water into steam. This steam is carried through pipes to a system of turbines, which spin at high speeds as the steam passes through. The turbines are connected to either a generator or a complex gearbox to then power essential functions throughout the ship or to turn the ship's propellers through the water.

(As previously mentioned, more information and corrections are welcomed. A quick note that much information surrounding the nuclear plants aboard ships remains classified, so make sure you don't violate the PATRIOT act before replying!)

The future of nuclear power lies not in bigger reactors, or different fuel types. The future lies in the opposite of splitting an atom: Fusing two together. Currently, scientists worldwide are pushing the boundries of scientific principle and resolve by attempting to create controlled fusion of hydrogen nuclei, to produce safe, clean energy. Some day we may have fusion powered carriers. The world simply must wait and see.

 

I hope you enjoyed this incomplete(VERY INCOMPLETE) guide to nuclear, shipboard power. I do not expect to ever update  this to include Weapons of Mass Destruction, as while they have become a vital role in submarine warfare, they simply do not add much to the dimensional aspects of naval development. As far as this thread is concerned, they are another weapon attached to a vessel. Thank you, and leave comments, additions, corrections, and verifications in the replies below!

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43 minutes ago, CaptLincoln said:

Nuclear Power has been the principle production method for several new classes of large, modern warships, from Frigates,

Which Frigates, or class of Frigates, are Nuclear powered?

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13 hours ago, Umikami said:

Which Frigates, or class of Frigates, are Nuclear powered?

I think the Bainbridge was the smallest, but she was a Destroyer (in modern parlance.)

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1 hour ago, TornadoADV said:

I think the Bainbridge was the smallest, but she was a Destroyer (in modern parlance.)

No ...

USS Bainbridge, CGN-25, was (and I am inserting a Wikipedia quote):

"The USS BAINBRIDGE (CGN-25), a nuclear version of the Leahy class cruiser, was commissioned on 6 OCT 1962 as DLGN-25. BAINBRIDGE was disposed of at the Puget Sound Naval Shipyard Nuclear Recycling Program in the late 1990s." (There are other facts in between, but this is the gist of it.)"

USS Bainbridge, DDG-96, is an Arleigh Burke class guided missile destroyer, and is not nuclear powered.

https://en.wikipedia.org/wiki/USS_Bainbridge_(CGN-25

Check out the second pic, showing Bainbridge, Long beach, and Enterprise together during Operation "Sea Orbit." The ship compares in size to the nuclear powered Long Beach; definitely a cruiser. Sorry you have to navigate through the first screen, but the link won't copy correctly.

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33 minutes ago, Umikami said:

No ...

USS Bainbridge, CGN-25, was (and I am inserting a Wikipedia quote):

"The USS BAINBRIDGE (CGN-25), a nuclear version of the Leahy class cruiser, was commissioned on 6 OCT 1962 as DLGN-25. BAINBRIDGE was disposed of at the Puget Sound Naval Shipyard Nuclear Recycling Program in the late 1990s." (There are other facts in between, but this is the gist of it.)"

USS Bainbridge, DDG-96, is an Arleigh Burke class guided missile destroyer, and is not nuclear powered.

https://en.wikipedia.org/wiki/USS_Bainbridge_(CGN-25

Check out the second pic, showing Bainbridge, Long beach, and Enterprise together during Operation "Sea Orbit." The ship compares in size to the nuclear powered Long Beach; definitely a cruiser. Sorry you have to navigate through the first screen, but the link won't copy correctly.

The Bainbridge was originally classified as a frigate or a destroyer, that got changed well before she was launched, probably because "Nuclear Powered Tin Can" sounded like a really dumb idea.

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16 hours ago, CaptLincoln said:

Friends, in the modern world, we have many different forms of power production. Global warming is promoted with Coal. Oil leaks into the fields of North Dakota, and fought over in the hills of the Middle East. Yet there remains one form that the navies of the world continue to develop, despite widespread fear of the results of a disaster. I am, of course, talking about Nuclear Power.

Over the years, Nuclear Power has been the principle production method for several new classes of large, modern warships, from Frigates, prowling the seas with specialized armament, to Cruisers, armed to the brim with support weapons, to the Carriers they protect, launching the warplanes to take down the ever-constant threat of the Nuclear Submarine, stealthily infiltrating the task force to deliver it's torpedo payload with deadly effect.

Many in the world fear the consequences of continued nuclear development. Millions recall with fear the deadly radiation clouds of Chernobyl and Fukishima(Apologize for spelling). Countless more have stared in horror at the devastating effects that one Little Boy had on Hiroshima, and the horrifying results of Fat Man on Nagasaki. It is true, in the brief history of Nuclear Power in the vast book of naval legacy that there have been many catastrophic events on land involving nuclear power, however, this fails to consider the effects that Nuclear Power has had at sea. The purpose of this thread is to update it over time to eventually contain the full understanding of Nuclear implications in the world of naval affairs. As such, until that day comes, which in my honest opinion should be never, this guide will remain incomplete. Starting in the 1940's, we will look at the history of nuclear naval development, and as we reach the present day will endeavor to explain how it functions, and will end with what the future may hold for humanity's navies in the world of the atom.

Before we begin, it should be noted that this is going to be missing quite a lot. The original copy of the thread was missing a lot more than just what you see here, as it was simply from my knowledge, and was built upon over time by the comments and replies from the community. It is the goal to have the community help verify and expand this guide so that a comprehensive description of the modern navy may exist. And with that, full steam ahead!

It's December 2nd, 1942. Countless scientists stand ready to react to the slightest sign of error under the bleachers of Stagg Field. A pile is the focus of their attention as they await the news to see if their baby could actually function in the world of reality, and not their own vivid imaginations. This experiment, come to be known as Chicago Pile-1, is the world's first nuclear reactor. Although primitive and unable to harness the energy it produced, it proved that sustained nuclear reactions were possible. Three years later, at Trinity Test Site in the New Mexico desert, the world's first atomic bomb was detonated, spreading ash and debris for hundreds of miles, the flash seen as far away as Las Vegas, Nevada. These land-based developments would become the foundation of the modern nuclear force of the United States. Before we begin launching missiles, however, let's look four thousand miles east, in the waters of the Pacific Ocean...

The Pacific Fleet, the pride of the United States Navy, has been fighting the Japanese for months. Thankfully, their carrier production has gone through the roof, and now has the upper hand against the enemy. Carriers had gone from being simple take off platforms to full scale airports on the water, able to refuel entire squadrons in an hour. These carriers had only two weaknesses: They were large, flat targets for enemy bombers, and secondly, they had to refuel. A lot. Refueling at sea is a dangerous operation, when the tanker and carrier must be connected for a long period of time, leaving both especially vulnerable to attack. This gets the U.S. Navy to thinking: Is there a better way?

(If there are people out there with more information on this subject for the years after this, please post it below! I would love to give you credit in future renditions of this thread! I simply have little information myself about the history of the development)

Nowadays, the United States Navy has a demand for nuclear propulsion officers and enlisted, alike. Particularly, the Navy has founded the Nuclear Propulsion Officer Candidates Program(NuPOC) to help fill the void in the force. Training involves tours of reactors, Nuke School, and training at one of the two prototype reactors on land before deployment overseas as the Engineering Officer of the Watch.

The history of the reactor propulsion system is all well and good, but how exactly does it work? Nuclear reactors come in various forms, and many materials are available to describe Breeder reactors and other types, but for the stripped down, basic version of how reactors work: The reactor itself, contained in a thick shield to prevent radiation leakage, contains fuel cells, made up of what tend to be pellets of the fuel. Often the fuel is Uranium, however other elements are available to be consumed. The reaction, once started, is controlled by "heavy water," a chemical isotope of regular water with more neutrons that slows the particles released by fissioning atoms down enough so that they may hit other uranium atoms, and by control rods, which absorb excess neutrons. These rods can be raised and lowered depending on the circumstances to control the rate of the reaction.

Heat is generated by the reactor, which is used to turn water into steam. This steam is carried through pipes to a system of turbines, which spin at high speeds as the steam passes through. The turbines are connected to either a generator or a complex gearbox to then power essential functions throughout the ship or to turn the ship's propellers through the water.

(As previously mentioned, more information and corrections are welcomed. A quick note that much information surrounding the nuclear plants aboard ships remains classified, so make sure you don't violate the PATRIOT act before replying!)

The future of nuclear power lies not in bigger reactors, or different fuel types. The future lies in the opposite of splitting an atom: Fusing two together. Currently, scientists worldwide are pushing the boundries of scientific principle and resolve by attempting to create controlled fusion of hydrogen nuclei, to produce safe, clean energy. Some day we may have fusion powered carriers. The world simply must wait and see.

 

I hope you enjoyed this incomplete(VERY INCOMPLETE) guide to nuclear, shipboard power. I do not expect to ever update  this to include Weapons of Mass Destruction, as while they have become a vital role in submarine warfare, they simply do not add much to the dimensional aspects of naval development. As far as this thread is concerned, they are another weapon attached to a vessel. Thank you, and leave comments, additions, corrections, and verifications in the replies below!

I should point out a few things you got very wrong here.  Commercial nuclear power is extremely safe.  It has an excellent track record outside of Russia, where Chernobyl happened.

Nobody died or got cancer as a result of Three Mile Island.  A few people may get cancer as a result of Fukushima, but we won't know for decades.  Nobody living near the plant will, and the levels of radiation in areas near the plant are almost all less than the residuals from Nagasaki or Hiroshima.

The one big disaster with a reactor is Chernobyl.  The operators were doing a test at two in the morning, and the guy supervising this wanted to deviate from the normal plan so the operators did.  The reactor was a fast fission, graphite moderated one that isn't used anywhere else in the world commercially because they're considerably less safe to begin with, and because they produce plutonium as a byproduct of operation.

Worse, the Chernobyl plant was shoddily built and had a substandard containment.  This is what you get when people aren't motivated to do a good job, aren't paid to do one, and the government is both corrupt and unaccountable.  That's how it was in the Soviet Union.  The result was the worst reactor disaster ever.  Yes, lots of people got cancer or died from that one.  But, that isn't how these plants are operated in the Western world.

As for naval nuclear power...

Ship's reactors are somewhat different than commercial ones.  They use highly enriched fuel for compactness.  Some variants have been tried unsuccessfully to make them even more compact like running the primary coolant as liquid sodium salts (highly corrosive, poisonous, and explosive if it gets in contact with water).  So, these reactors have pretty much been uniformly pressurized water types (PWR).

The US nuclear power program comes in three parts for people in it:  Enlisted go to an A School for their rating, officers get basic officer training.  Then they go to nuclear power school for classroom instruction.  Get your associate's degree in nuclear engineering in six months as I like to call it.  Then prototype where you have to memorize your first reactor system and prove you can operate it without screwing up.  You'd be surprised how many really "book smart" guys can't do the hands on portion and barely scrape by.

Then it's off to a ship and do it again.

The USN, and other Western Navies have strived to make their plants as safe and reliable as possible.  The Soviets had serious problems with their nuclear plants and these were, in many cases, on-going.

Nuclear weapons are a whole 'nother thing.  

 

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53 minutes ago, SgtBeltfed said:

The Bainbridge was originally classified as a frigate or a destroyer, that got changed well before she was launched, probably because "Nuclear Powered Tin Can" sounded like a really dumb idea.

First, you did notice where the Wiki said it was a heavily modified Leahy class Cruiser, and, Second, even if it was a DD, which it wasn't, a DD is not a Frigate. There are not now, nor have there ever been, any nuclear powered Frigates.

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22 minutes ago, Umikami said:

First, you did notice where the Wiki said it was a heavily modified Leahy class Cruiser, and, Second, even if it was a DD, which it wasn't, a DD is not a Frigate. There are not now, nor have there ever been, any nuclear powered Frigates.

Read the entire line you're quoting, it also refers to her a a Destroyer leader, which was considered a frigate. I've also seen her referred to as a frigate in official publications. The Leahy class has the same issue, they were built as destroyer leaders, and later redesignated as cruisers. The US Navy has from time to time, been confused as to what to call a ship. You see it today with the LCS's, which are basically frigates in everything but name.

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2 minutes ago, SgtBeltfed said:

Read the entire line you're quoting, it also refers to her a a Destroyer leader, which was considered a frigate

A Frigate is smaller than a Destroyer Escort, which is smaller than a Destroyer, which is smaller than a Destroyer leader. Yubari is technically a Destroyer leader, as are Tashkent and Nicholas. None are Frigates; you're wrong.

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3 minutes ago, Umikami said:

A Frigate is smaller than a Destroyer Escort, which is smaller than a Destroyer, which is smaller than a Destroyer leader. Yubari is technically a Destroyer leader, as are Tashkent and Nicholas. None are Frigates; you're wrong.

Ok, little history lesson. In the US Navy, frigates started out as the equivalent of a cruiser, USS Constitution is a frigate. She was the biggest ship that wasn't a ship of the line, AKA, Battleship.

The term disappeared before WWI in the US Navy. The term resurfaced in the 1960's when destroyers started getting big. The Bainbridge, Long Beach, Leahy and Coontz classes are from this period of time.

The US Navy had a little problem in the 1970's, and the fix was to reclassify them. United States Navy 1975 ship reclassification (funny, it's actually a historical event, I never gave it that much credit)

At some point later, the US Navy built the Knox class, and called the frigates, they are the equivalent of a destroyer escort from WWII. By any other nations standards they're corvette's. Modern US Navy DD's by other nations rules are cruisers, their frigates are destroyers by USN standards.

If you're gonna call me wrong, do your research. 

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4 hours ago, SgtBeltfed said:

Ok, little history lesson. In the US Navy, frigates started out as the equivalent of a cruiser, USS Constitution is a frigate. She was the biggest ship that wasn't a ship of the line, AKA, Battleship.

The term disappeared before WWI in the US Navy. The term resurfaced in the 1960's when destroyers started getting big. The Bainbridge, Long Beach, Leahy and Coontz classes are from this period of time.

The US Navy had a little problem in the 1970's, and the fix was to reclassify them. United States Navy 1975 ship reclassification (funny, it's actually a historical event, I never gave it that much credit)

At some point later, the US Navy built the Knox class, and called the frigates, they are the equivalent of a destroyer escort from WWII. By any other nations standards they're corvette's. Modern US Navy DD's by other nations rules are cruisers, their frigates are destroyers by USN standards.

If you're gonna call me wrong, do your research. 

You beat me to it Sgt.  I was a sailor at the tail end of that era when the Leahy, Belknap, Bainbridge and other DLG / DLG(N)s were reclassified as cruisers.  It was during this period that the last of what I still think of as REAL cruisers were taken out of service, ships like the modified Cleveland class USS Little Rock (CLG and later CG,) USS Chicago and USS Albany (CGs built from Baltimore and Oregon City class CAs) as well as the one off USS Long Beach (CG(N).) 

Today we have only one class of "cruiser" remaining in the USN, the Ticonderoga class (CG) which actually started out and the first laid down as DDG-47, a modified Spruance destroyer.  For most intents and purposes, from the main deck down these ships are Spru-cans.  The real differences are above the main deck with a larger and heavier superstructure and electronics fit.

I've often thought that the US Navy "missed the boat" by getting rid of the 31 original Spruances.  Those hulls had between 15 and 25 years of life left in them when removed from service, more if they received a SLEP type overhaul to refit them with a new superstructure and electronics fit based on the Burke type combined with the larger missile magazine capacity of the 122 cell VLS fit of the VLS Ticonderoga type.

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On 5/12/2018 at 1:54 PM, Murotsu said:

I should point out a few things you got very wrong here.  Commercial nuclear power is extremely safe.  It has an excellent track record outside of Russia, where Chernobyl happened.

Nobody died or got cancer as a result of Three Mile Island.  A few people may get cancer as a result of Fukushima, but we won't know for decades.  Nobody living near the plant will, and the levels of radiation in areas near the plant are almost all less than the residuals from Nagasaki or Hiroshima.

The one big disaster with a reactor is Chernobyl.  The operators were doing a test at two in the morning, and the guy supervising this wanted to deviate from the normal plan so the operators did.  The reactor was a fast fission, graphite moderated one that isn't used anywhere else in the world commercially because they're considerably less safe to begin with, and because they produce plutonium as a byproduct of operation.

Worse, the Chernobyl plant was shoddily built and had a substandard containment.  This is what you get when people aren't motivated to do a good job, aren't paid to do one, and the government is both corrupt and unaccountable.  That's how it was in the Soviet Union.  The result was the worst reactor disaster ever.  Yes, lots of people got cancer or died from that one.  But, that isn't how these plants are operated in the Western world.

As for naval nuclear power...

Ship's reactors are somewhat different than commercial ones.  They use highly enriched fuel for compactness.  Some variants have been tried unsuccessfully to make them even more compact like running the primary coolant as liquid sodium salts (highly corrosive, poisonous, and explosive if it gets in contact with water).  So, these reactors have pretty much been uniformly pressurized water types (PWR).

The US nuclear power program comes in three parts for people in it:  Enlisted go to an A School for their rating, officers get basic officer training.  Then they go to nuclear power school for classroom instruction.  Get your associate's degree in nuclear engineering in six months as I like to call it.  Then prototype where you have to memorize your first reactor system and prove you can operate it without screwing up.  You'd be surprised how many really "book smart" guys can't do the hands on portion and barely scrape by.

Then it's off to a ship and do it again.

The USN, and other Western Navies have strived to make their plants as safe and reliable as possible.  The Soviets had serious problems with their nuclear plants and these were, in many cases, on-going.

Nuclear weapons are a whole 'nother thing.  

 

Personally, I agree with what you said about commercial power being safe. As for the navy, that is really interesting. I simply got the information about NuPOC off the USN website. What I get for trusting the government. Thanks for the feedback, I'll be sure to update ASAP!

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When talking about Naval Nuclear Propulsion Plants it is important to remember what sort of plants we use compared to other navies and even civilian organizations.  One should also remember the mantra of nukes everywhere... "hot rock, make steam, make boat go".

In the United States Navy we do not use heavy water reactors...  We use regular (well mostly, it is deionized and distilled) water.  Specifically, we use what are called "pressurized water reactors".  We do not use boiling water reactors or liquid metal reactors.

Now, moving more into the operations and theory side of things.  The following will be incomplete due to national security concerns, but to explain the source of my information, I was a Nuclear Machinist Mate and an Engineering Laboratory Technician.  I did A-school, Power school, prototype and the ELT C-school then went on to serve on board a 688 class submarine.

Obviously the process starts in the reactor itself.  We use fission to generate both heat and neutrons (to continue the reaction).  We have all hear terms like "the reactor is critical".  That is a good thing, it means the reactor is stable and operating at an unchanging power level (neutrons in = neutrons produced).  Sub-critical means the power level is decreasing (neutrons in > neutrons produced).  Super-critical is also not a bad thing in and of itself, it means the power level is increasing (neutrons in < neutrons produced).  Super-critical is only a problem if you go too far or if it is uncontrolled.

Which brings us back to reactor design.  Control rods allow us to start up, shut down and alter the power level of the reactor by absorbing neutrons.  With the rods all the way in, you absorb the most neutrons, this reduced power and will shut down the reactor.  Raising the rods exposes more nuclear fuel and absorbs fewer neutrons, allowing us to increase the power level.  The pressurized water reactor using distilled and deionized water has another nifty feature, water temperature changed the power level as well.  Temperature goes down, the water becomes more dense and it more effectively thermalizes neutrons, increasing the power.  Temperature goes up, the water becomes less dense and it thermalizes neutrons less efficiently, reducing the likelihood of thermal fission and thus lowering the power level.  By having the water under pressure, we raise the boiling boil substantially, keeping the water liquid.  This also acts as a safety feature.  If we were to in theory have a loss of water (say a section of piping falls out or something crazy like that) the water will obviously start to boil off and we lose the moderating effect...meaning fewer neutrons to cause continued fission.  The reactor will effectively try to shut itself down.  That of course assumes that the mechanical interlocks fail and the operator is not paying attention.  If those are as they should be, you will also have the control rods rapidly inserted to further reduce power in a quick and fast manner.  Essentially, the chance for a nuclear explosion is zero and the chance of a meltdown is very low with a pressurized water reactor.

But moving on, we now have a reactor that produces heat via fusion.  The hot rock is accounted for.  We must now make steam.  We use a two loop system, which is a containment and safety feature.  The radioactive stuff stays in one place that is away from the people.  The hot water leaving the reactor enters a vessel.  Also in this vessel there is more water from the other loop.  The two are separated by piping.  The water in the secondary loop is heated via conduction through the piping until it flashes to steam.  This vessel is imaginatively named a "steam generator".

We not have the "make steam" part covered.  We must make that steam work for us somehow.  This is done via turbines.  The steam acts on the blades of the turbine, causing it to spin.  The turbine output is either a generator or it drives a shaft.  Because turbines spin at a very high rate of speed, it would not be an effective propulsion system.  We thus use reduction gears to reduce the RPM's and increase the torque.  Ultimately, the reduction gears lead to a shaft and a screw.  The screw turns and we make the boat go.

In both the secondary and primary systems we are extracting heat at one point and adding heat at another point.  One has to get the water between those points as well.  In a closed system you can use natural circulation.  But when you have phase changes and such (like in the secondary) you need to get the steam back into liquid form, so we condense it in a heat exchanger (creatively called a condenser).  We then use pumps to move the water back to the steam generator.  On the primary side, if we are not using natural circulation we also use pumps.  One the water returns to the heat input device (steam generator or reactor) the process repeats.

A basic diagram follows.  Black is the primary loop, blue the secondary loop.  Brown the output of the turbines and green the cooling fluid for the condenser.

Discussion on things like radiation, containment, contamination and shielding may follow at a later time.

heatcycle.jpg

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On 5/11/2018 at 11:56 PM, CaptLincoln said:

The reaction, once started, is controlled by "heavy water," a chemical isotope of regular water with more neutrons that slows the particles released by fissioning atoms down enough so that they may hit other uranium atoms, and by control rods, which absorb excess neutrons.

Eh... Heavy water reactors are typically used for older civilian power production (see also: CANDU) or weapons production, and have never been used as shipboard propulsion plants. Something about not being able to get deuterium underway if you have to an add to the primary, not to mention the cost of producing it. 

Most shipboard power plants use water and rely on very high enrichment, or use moderators like sodium or other liquid metals (mostly Russian designs). After we experimented with it in USS Seawolf (SSN-575), it was decided not to pursue that type of reactor for US Navy applications, even though it provided a much higher power density than a PWR. 

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On 5/30/2018 at 8:59 AM, MM2ss said:

I was a Nuclear Machinist Mate and an Engineering Laboratory Technician.  I did A-school, Power school, prototype and the ELT C-school then went on to serve on board a 688 class submarine.

Hello, fellow nuke! What class were you in? 0006 here. 

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Went to nuke school back in 02/03.  Don't remember the class number, but RTC I was in div. 326.  (Odd the things one remembers at times)

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Stupid question here, so the steam that comes out of the steam generator do you run it back thru the steam generator to super heat the steam?   I.e. how do you go from saturated steam to super heat before you send it to the turbines.   

From what little I remember, any moisture in the steam ends up destroying the turbine, so in a conventional steam boiler you send the steam back in to the boiler (specifically back into the firebox in between the generating bank tubes) to super heat it.   How would you guys do it with the steam generator? Is there a similar mechanism?  In the steam drum of the boiler, we do have moisture separators to separate out water droplets out of the steam, but youre still left with saturated steam so back into the boiler you go...

I only got to spend a month aboard Arkansas (CGN-41) they sent us down to the plant to watch engineering drills all I remember was drills where they scrammed the reactors all the time, so scramming and restarting the reactors appeared to be normal thing.  One time they were running drills between the two reactor compartments and they didn’t get the first reactor critical before they ran the drill on the second reactor and scrammed the second reactor and well there goes propulsion and power until the emergency diesels came back online. The ship wallowed in the wave troughs until they were able to restore propulsion. CO was quite unhappy with CHENG for that episode.

thanks

 

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Not a stupid question at all.  There are different types of steam systems.  Each system has its' own specs for proper operation.  I will not be discussing any particulars (OPSEC, classified material, etc.), but rather in general terms.

Superheating steam requires increasing the temperature without increasing the pressure...which means you have to increase the volume for the steam.  Superheated steam also requires additional process (to superheat it) and requires specialized processes to be added to the system to cope with the use of superheated steam.

Saturated steam is obviously at saturation pressure and temperature.  It is more efficient at heat transfer and is generally easier to use.  But as you noted, one must be wary of things like water droplets impinging on the turbine blades.

There is a third type of steam.  "Dry steam".  It is technically superheated, but just barely, not enough to really act like superheated steam in terms of heat transfer, but it carries far less water in it.

Most nuclear power plants just use saturated steam or dry steam.  To deal with things like water droplets, you can use traps, moisture separators and ejectors.  This give a means of removing liquid from the steam while letting the system run in a reasonably efficient manner.

---------------------------------------

SCRAMing the reactor is not a "normal" thing.  Yes, we do test the function, and it is done from time to time with drills in certain situations.  But for shutdowns and such we normally "drive" the control rods to the bottom.  A SCRAM causes a shot to the reactor and that is not something we like to do.  You noted a loss of propulsion until generators were online.  Which in the surface fleet in a non-emergency situation makes sense.  In an emergency situation you can still draw power (in the form of heat energy) after a SCRAM.  But doing so is at the cost of temperature.  The decay heat is far less than the heat generated when at normal critical operational condition.  So you can still make steam in the secondary system and spin the turbines, but you are cooling off the primary system in doing so.  One would rather bring the primary back online properly before using it as a power source, but in an emergency, all bets would in theory be off.

The CO was justifiably angry with the ENG as during drills maintaining ship safety (like say propulsion and steering) is far more important than running the next drill.  The drill monitors and the END should have been chewed out thoroughly and at least some of them disqualified and retrained.

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Just my two bits on the safety of Nuclear power.

You may hear a lot of people worrying about stuff like background radiation and fallout after things like Fukashima and Chernobyl.  The thing is while those were bad events the amount of radiation released into the atmosphere is peanuts compared to the amount released by fossil fuels.  Yes fossil fuels release radiation into the atmosphere.  All that carbon they produce, well a portion of it is radioactive, just one of the reasons why its not good to breath that crapin.  Millions of people around the globe die every year of the effects of breathing in carbon pollution.  If you live in a city, your lifespan was likely shortened by up to five years because of it.

Point being that Nuclear power isn't just safe, its way the hell safer than what we have right now even if there was a Chernobyl every [edited]year.

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On 5/30/2018 at 7:59 AM, MM2ss said:

When talking about Naval Nuclear Propulsion Plants it is important to remember what sort of plants we use compared to other navies and even civilian organizations.  One should also remember the mantra of nukes everywhere... "hot rock, make steam, make boat go".

In the United States Navy we do not use heavy water reactors...  We use regular (well mostly, it is deionized and distilled) water.  Specifically, we use what are called "pressurized water reactors".  We do not use boiling water reactors or liquid metal reactors.

Now, moving more into the operations and theory side of things.  The following will be incomplete due to national security concerns, but to explain the source of my information, I was a Nuclear Machinist Mate and an Engineering Laboratory Technician.  I did A-school, Power school, prototype and the ELT C-school then went on to serve on board a 688 class submarine.

Obviously the process starts in the reactor itself.  We use fission to generate both heat and neutrons (to continue the reaction).  We have all hear terms like "the reactor is critical".  That is a good thing, it means the reactor is stable and operating at an unchanging power level (neutrons in = neutrons produced).  Sub-critical means the power level is decreasing (neutrons in > neutrons produced).  Super-critical is also not a bad thing in and of itself, it means the power level is increasing (neutrons in < neutrons produced).  Super-critical is only a problem if you go too far or if it is uncontrolled.

Which brings us back to reactor design.  Control rods allow us to start up, shut down and alter the power level of the reactor by absorbing neutrons.  With the rods all the way in, you absorb the most neutrons, this reduced power and will shut down the reactor.  Raising the rods exposes more nuclear fuel and absorbs fewer neutrons, allowing us to increase the power level.  The pressurized water reactor using distilled and deionized water has another nifty feature, water temperature changed the power level as well.  Temperature goes down, the water becomes more dense and it more effectively thermalizes neutrons, increasing the power.  Temperature goes up, the water becomes less dense and it thermalizes neutrons less efficiently, reducing the likelihood of thermal fission and thus lowering the power level.  By having the water under pressure, we raise the boiling boil substantially, keeping the water liquid.  This also acts as a safety feature.  If we were to in theory have a loss of water (say a section of piping falls out or something crazy like that) the water will obviously start to boil off and we lose the moderating effect...meaning fewer neutrons to cause continued fission.  The reactor will effectively try to shut itself down.  That of course assumes that the mechanical interlocks fail and the operator is not paying attention.  If those are as they should be, you will also have the control rods rapidly inserted to further reduce power in a quick and fast manner.  Essentially, the chance for a nuclear explosion is zero and the chance of a meltdown is very low with a pressurized water reactor.

But moving on, we now have a reactor that produces heat via fusion.  The hot rock is accounted for.  We must now make steam.  We use a two loop system, which is a containment and safety feature.  The radioactive stuff stays in one place that is away from the people.  The hot water leaving the reactor enters a vessel.  Also in this vessel there is more water from the other loop.  The two are separated by piping.  The water in the secondary loop is heated via conduction through the piping until it flashes to steam.  This vessel is imaginatively named a "steam generator".

We not have the "make steam" part covered.  We must make that steam work for us somehow.  This is done via turbines.  The steam acts on the blades of the turbine, causing it to spin.  The turbine output is either a generator or it drives a shaft.  Because turbines spin at a very high rate of speed, it would not be an effective propulsion system.  We thus use reduction gears to reduce the RPM's and increase the torque.  Ultimately, the reduction gears lead to a shaft and a screw.  The screw turns and we make the boat go.

In both the secondary and primary systems we are extracting heat at one point and adding heat at another point.  One has to get the water between those points as well.  In a closed system you can use natural circulation.  But when you have phase changes and such (like in the secondary) you need to get the steam back into liquid form, so we condense it in a heat exchanger (creatively called a condenser).  We then use pumps to move the water back to the steam generator.  On the primary side, if we are not using natural circulation we also use pumps.  One the water returns to the heat input device (steam generator or reactor) the process repeats.

A basic diagram follows.  Black is the primary loop, blue the secondary loop.  Brown the output of the turbines and green the cooling fluid for the condenser.

Discussion on things like radiation, containment, contamination and shielding may follow at a later time.

heatcycle.jpg

If I remember my training in Groton CT from sub school in 1988, And I have not Officially been notified otherwise, That drawing was part of a classified instruction manual that isn't supposed to be disclosed. Have the rules been changed?

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You can find the same drawing in most text books as well as online.  You will note that there is nothing present in that drawing that is not public information.  The classification assigned to the more detailed version one would find at subschool or NNPTC is NOFORN, but it has a great deal more information and detail.  I made sure to verify that my simplified diagram adhered to proper material controls and conformed to public domain standards.  Euronuclear and the World Nuclear Association both have more detailed versions than what I posted publicly available.

  • Cool 1

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5 hours ago, MM2ss said:

You can find the same drawing in most text books as well as online.  You will note that there is nothing present in that drawing that is not public information.  The classification assigned to the more detailed version one would find at subschool or NNPTC is NOFORN, but it has a great deal more information and detail.  I made sure to verify that my simplified diagram adhered to proper material controls and conformed to public domain standards.  Euronuclear and the World Nuclear Association both have more detailed versions than what I posted publicly available.

Some company level officer would still have a field day with violating grey information protocols, they have nothing better to do.

  • Funny 1

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They are welcome to try.  Then again, as the ELT on a submarine I was the one in charge of determining what the various manuals actually said and meant because I was the "subject matter expert" on board.  I am willing to wager that I could make such an officer look like a complete and utter idiot if the military decided to recall me for military legal proceedings, particularly when I refused mast and demanded a court martial.  At that point the rules of evidence apply and I would greatly enjoy bringing up all the far more detailed public diagrams to demonstrate that I revealed no military or national security information.  After that finished up, I would then proceed to the civilian legal arena as Feres would not apply to such a case.  I suspect I could recoup all my costs and make a decent profit in the end.

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1 hour ago, MM2ss said:

They are welcome to try.  Then again, as the ELT on a submarine I was the one in charge of determining what the various manuals actually said and meant because I was the "subject matter expert" on board.  I am willing to wager that I could make such an officer look like a complete and utter idiot if the military decided to recall me for military legal proceedings, particularly when I refused mast and demanded a court martial.  At that point the rules of evidence apply and I would greatly enjoy bringing up all the far more detailed public diagrams to demonstrate that I revealed no military or national security information.  After that finished up, I would then proceed to the civilian legal arena as Feres would not apply to such a case.  I suspect I could recoup all my costs and make a decent profit in the end.

It would not surprise me if someone still tried. They are a special breed, they are. :cap_book:

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