USS Connecticut has undersea collision

originally posted by: penroc3
There is a reason that stuff is top secret and i think we are bumping up against that wall.

that cooling loop, what happens to the water in that loop cooling the heat exchangers starts to boil? how do you cool the cooling loop?

You said it "top secret" I was allowed to see the reactor when I spent some time on a sub. I was NOT allowed to see the heat exchangers.

a reply to: penroc3

You

subs don't stay under water all the time

That is correct. They are not made to be stealthy on the surface. There they can be detected by sight, or by radar.

you know what makes a better shielding? ROCK. And somehow we can still pick up missiles in silos and other underground facilities.

Depends on it’s type, density, and attenuation factor.

Things in rock are not as mobile as submarines. And submarines can change their area of operation. A facility built in rock pretty much stuck. And once it’s location is known, it’s known.

And the mined rock has to be moved someplace to pile up.

Middleoftheroad: I get how it works but there is always waste heat from reactors,

Depends on how long a reactor has been shutdown, and what amount of fission products are decaying.

Control rods do a good job of of capturing neutrons to prevent a shut down rector from “startling up.” Bit yes. If I remember right. Fuel Rods that have never initiated fission don’t need to be covered in water.

Also…

Dry Cask Storage

In the late 1970s and early 1980s, the need for alternative storage began to grow when pools at many nuclear reactors began to fill up with stored spent fuel. Utilities began looking at options such as dry cask storage for increasing spent fuel storage capacity.

Dry cask storage allows spent fuel that has already been cooled in the spent fuel pool for at least one year to be surrounded by inert gas inside a container called a cask. The casks are typically steel cylinders that are either welded or bolted closed. The steel cylinder provides a leak-tight confinement of the spent fuel. Each cylinder is surrounded by additional steel, concrete, or other material to provide radiation shielding to workers and members of the public. Some of the cask designs can be used for both storage and transportation.

www.nrc.gov...

Small reactors that would fit on a sub would have a HIGH power density and would run hotter than a normal reactor,

Total BS on “hotter” all fuel rods with pellets in cladding are limited to safe temperatures for the cladding.

Also. If you power up a fuel rod to fast, gaseous decay products can create gas pockets that can blow out the cladding of a fuel pellets that protect them from erosion by the coolant.

I get it can go to hot water tanks and heating systems and what not but you cant keep cycling the same water with out cooling it all the way off so that way it turns back to water. Over time it will creep higher and higher until they can dump the heat into SOMETHING.

Like dumping heat to steam generators? That pushes steam through main condensers cooled by sea water. The steam is cooled off by the seawater, and condensed back to steam.


After a few days in port. The sea water to the main condensers are secured. The main steam valves to the heat exchangers are shut. The reactor sits there shut down, with just giving heat up to the reactor compartment. With the primary coolant pumps shut down.

I GUESS they could try and balance the power for the needs of the boat but still that is a risky game as well.

Not like you make it sound.

The water serves several purposes. First, it serves as a heat sink, keeping the core at the designed temperature. Second, it slows the "fast" neutrons (about 1 MeV of kinetic energy) produced by fission to thermal speeds, which correspond to kinetic energies of about 30 meV. This slowing of neutrons sustains the reaction, as thermal neutrons are significantly more likely to cause fission events than fast neutrons. In accomplishing both of these tasks, the water boils as it absorbs a large amount of the energy released by the reaction. The steam produced in the reactor core then drives a turbine, which converts most of the steam's energy into electrical power (see Fig. 1). Finally, the water condenses and is pumped back into the reactor core, making a circuit. [2]

As these reactors require water to sustain fission, a safety feature built into the design is that the reaction rate decreases as the proportion of water to steam decreases in the core. As such, an increase in heat generated by the core will cause the water to steam ratio to decrease and the reaction rate to slow and the core to cool. This feature ensures that BWRs are incapable of producing runaway reactions and becoming fission "bombs."

that cooling loop, what happens to the water in that loop cooling the heat exchangers starts to boil? how do you cool the cooling loop?

The reactor is operated at a pressure where the water doesn’t “boil”. The primary coolant flows through tubes in a steam generator. The heat crosse through the subs to heat secondary water to creat steam that powers the steam turbines. The steam is cooled in the main condensers by sea water and returned to water. The condensed water is pumped back into the steam generator.


Well. Unless it’s a reactor where the primary coolant is also the water used to make stream to power steam turbines…..

Typical Boiling-Water Reactor

How Nuclear Reactors Work

In a typical design concept of a commercial BWR, the following process occurs:

The core inside the reactor vessel creates heat.
A steam-water mixture is produced when very pure water (reactor coolant) moves upward through the core, absorbing heat.
The steam-water mixture leaves the top of the core and enters the two stages of moisture separation where water droplets are removed before the steam is allowed to enter the steamline.
The steamline directs the steam to the main turbine, causing it to turn the turbine generator, which produces electricity.

www.nrc.gov...

a reply to: neutronflux

I should have said water goes under a phase change to steam under high pressure and heat


A sub is a small space and there for the reactor on board has to be smaller than a land based reactor, The power generation numbers I believe are still classified so I don't know what they are exactly but it is safe to say that it is easily a few 100 kWs. that is so much heat to have to deal with.

a smaller reactor vessel in a sub would be hotter than its land based sister, the amount of space to get the same amount of power is drastically reduced so it would HAVE to run hotter and at a very high enrichment but they don't carry extra robs on the boat or store them on the boat.

they load and start the reactor and that's that. IF the boat is still around when the rods need to be changed(some naval reactors have a 20 year life span before it needs to be refueled) the rods are taken to a land based storage and processing facility like LLNL or similar places.

Normal reactors have tons of thermal mass to dissipate the heat into as well as cooling towers to vent the waste heat.

There is no power generation method that can convert heat into power at 100%, what happens to the the now well past boiling water/steam after its out of the turbines? dump it into the limited cooling water so it can be redistributed? possibly but there would still be a net gain of heat in the system.

I guess they could be using molten salt reactors but that is highly unlikely as the coolant blows up in contact with water.

when the boat needs to slow down really fast and just cuts the screws, what happens to all power/steam that was going to them? where is that dumped in the system?

what about when they go silent? they aren't going to scram the reactor so what happens to all that supercritical steam and its now waste heat?


you cant just start a reactor back up like flipping a light switch, it takes a good amount of time so it has to always be running no matter what. Say all the O2 tanks are filled the water is desalinated and the batteries are charged so there is little to no power draw off the reactor itself, so if that is the case where are they putting the heat or even the power from the reactor if all the power isn't all needed?



and your NRC link is talking about land based reactors.

its to bad we cant get a true diagram on current reactors in subs.

it would no doubt be impressive.

a reply to: penroc3

There is no power generation method that can convert heat into power at 100%,

The waste heat is dumped into sea water across the main condensers tubes.

when the boat needs to slow down really fast and just cuts the screws, what happens to all power/steam that was going to them? where is that dumped in the system?

Again…

The water serves several purposes. First, it serves as a heat sink, keeping the core at the designed temperature. Second, it slows the "fast" neutrons (about 1 MeV of kinetic energy) produced by fission to thermal speeds, which correspond to kinetic energies of about 30 meV. This slowing of neutrons sustains the reaction, as thermal neutrons are significantly more likely to cause fission events than fast neutrons. In accomplishing both of these tasks, the water boils as it absorbs a large amount of the energy released by the reaction. The steam produced in the reactor core then drives a turbine, which converts most of the steam's energy into electrical power (see Fig. 1). Finally, the water condenses and is pumped back into the reactor core, making a circuit. [2]

As these reactors require water to sustain fission, a safety feature built into the design is that the reaction rate decreases as the proportion of water to steam decreases in the core. As such, an increase in heat generated by the core will cause the water to steam ratio to decrease and the reaction rate to slow and the core to cool. This feature ensures that BWRs are incapable of producing runaway reactions and becoming fission "bombs."

The electrical steam turbines are still consuming steam.

Control rods can be driven in to “suck up” neutrons to curve the reaction rate.

If there is too much of a power excursion, the reactor scrams, the control rods drop. The reactor “shuts down”. The sub goes to diesel (if at snorkel delth) and or battery backup.

what about when they go silent? they aren't going to scram the reactor so what happens to all that supercritical steam and its now waste heat?

.

Scrams are auto controlled by reactor controls. It can be over ridden to only save the ship.

Underway. We train for reactor scrams. Recovering from a reactor scram takes minimal time to recover from.

a reply to: penroc3

Going from ahead flank to all stop is not a problem at all. It’s normal.

Loosing reactor coolant pumps, and sea water flow is a huge problem. Like sea weed and sea life fouling main condenser tubes, and may lead to limiting the power that should be created by the reactor.

a reply to: neutronflux



I have been inside a local reactor building when they were bringing it up and I think it took them 2 days to get back up to normal power levels that were stable.



but that is a land based PWR running at I think 550MW so it is a different ballgame.

I would LOVE to see some blueprints for the reactors on our newest subs, its to bad they are kept secret.

the size and power of those reactors could be used to make modular power stations, instead of refueling and storing rods on site the company comes and replaces the vessel and on you go. sounds crazy but there is a serious push to make small modular reactors.

a reply to: penroc3

I have been inside a local reactor building when they were bringing it up and I think it took them 2 days to get back up to normal power levels that were stable.

Sub reactors are built smaller, and made more conservative/ inherently safe.

For reactors, especially larger reactors, lots of time goes into holding at specific temperatures for heat soak times to prevent reactor vessel cracking / fracturing. Larger the vessel, more susceptible to thermal stress from uneven heating and damage if a heat up schedule is not properly followed.

And it depends on the condition of the reactor at start up.

From what would be considered a startup from a normal in port shutdown conditions, a sub reactor can start up and steam out of port in lot less than one day.

As for smaller nuclear reactors…..

Stationary Low-Power Reactor Number One, also known as SL-1 or the Argonne Low Power Reactor (ALPR), was a United States Army experimental nuclear reactor located at the National Reactor Testing Station (NRTS), basis of what is now the Idaho National Laboratory, west of Idaho Falls, Idaho, United States. At 9:01 pm, on the night of January 3, 1961, SL-1 underwent a steam explosion and meltdown, killing its three operators.[1][2][3][4] The direct cause was the improper withdrawal of the central control rod, responsible for absorbing neutrons in the reactor's core. The event is the only reactor accident in U.S. history to have resulted in immediate fatalities.[5] The accident released about 80 curies (3.0 TBq) of iodine-131,[6] which was not considered significant due to its location in the remote high desert of eastern Idaho. About 1,100 curies (41 TBq) of fission products were released into the atmosphere.[7]

en.m.wikipedia.org...

Something that could be easily transported could easily be stolen.


Many thought this was the future of nuclear reactors.

The pebble-bed reactor (PBR) is a design for a graphite-moderated, gas-cooled nuclear reactor. It is a type of very-high-temperature reactor (VHTR), one of the six classes of nuclear reactors in the Generation IV initiative.

en.m.wikipedia.org...

Thank you for your service sir. My grandpa was a WWII sub vet stationed in Alaska. He always said it was fine on the surface but going under was like descending in a steel coffin. reply to: Middleoftheroad

Supposedly a commercial satellite image of the USS Connecticut after the incident. TBH, doesn't look like anything I can easily make sense of to my untrained eye.

Any ideas?

a reply to: neutronflux

SL-1 was WAY back in the 60's and was an experimental reactor and i think was the one the control rods impaled 2 workers into the ceiling right?


i have only been to the reactors on land so that is my life experience, everyone i know from various branches of service who dealt with reactors keep the lips sealed.

Reactor sites on the ground are VERY heavily guarded and have some very nasty tricks at the national labs if you were tying to sneak in.


i don't know how you would steal a running reactor or even a fuel bundle or for that matter a spent fuel bundle.

I was at a site in upstate ny that had a rubber ducky floating in the cooling pools for the spent rods. The rods year a few years old and still glowing a bright bright blue.

i don't know how diversion takes place outside manufacturing facilities, to get your hand on even spent fuel would be a death sentence.

it is kind of like a built in theft deterrent, getting your insides liquefied by intense radiation doesn't sound like a fun way to go.

the modular units were to be inside smaller power plants and were a sealed system and no one changed out rods or stored rods on site. It is actually a better model for anti diversion methods. And when i say modular the inserts are over 2 stories high.


i think the thorium salt reactors are going to be something to watch.

a reply to: penroc3

They can slow down the reaction with control rods(usually graphite that absorbs neutrons). All nuclear powered naval vessels are driven by electric engines, the reactors power generators so they can go to full speed on the prop to nothing fairly easy.

Cooling is a mystery, however deep ocean water is cold. Unfortunately the heat signature could give away their location.

The US Navy does not use molten salt reactors as a power plant for their vessels.

a reply to: Borys

Sub on the surface. Seen them from the air many times.

a reply to: jrod

graphite isn't used any more as a neutron moderator


control rods are neutron poisons like boron or beryllium or anything that absorbs neutrons, graphite only moderates the reaction not shut it down. the rods need to fit into the fuel bundle slots.

that is how the first uranium and weapons grade uranium was made in a graphite reactor that they would slide fuel elements out the back to be processed to extract the uranium and other side products.


and i know they don't use salt reactors in subs, that is just a dumb assumption. MOLTEN salt reactors need to be on a stable platform as they are mostly liquid as well as the fuel, what do you think would happen on an emergency dive or surface with that HIGHLY enriched molten salt spills all over the reactor room?

i said that they are an up in coming technology in the nuclear industry like the pebble reactor.


If any of you that i know are in Upstate NY i can offer a few people a tour of one of the power stations here and you can talk to the real experts.

a reply to: Bigburgh

A whale?
A whale would bounce off not causing damage.

A whale can cause a lot of damage to even a large vessel.

a reply to: jlgreer1

not connected but cool

a reply to: penroc3

It’s been a long time and I wasn’t even a nuclear guy. For what it’s worth, if I remember correctly it’s cooled by new sea water being pumped in, which circulates around the core to cool the reactor. As the sea water heats up and turned to steam, the steam is vented to other systems and more sea water is pumped into the reactor cooling loop for continued cooling.

a reply to: Zaphod58

But, why on Earth did the US Navy report such an incident? Whom are they interested to know it? And why?

a reply to: Middleoftheroad

but the water it takes in for cooling has to be dumped overboard at sometime or the sib would blow up like a balloon storing all that water

Holly cow.

The core is gives up heat to the primary loop. The primary loop dumps it heat to the second loop through heat exchangers cooled steam generators. As long as the secondary is making steam, the core has a place to dump its heat.

The secondary loop is a steam cycle. Heat from the reactor through the primary loop and the seam generators makes steam. The steam looses its energy in the electrical steam turbines which are constantly running when there is sufficient steam being made. Then there is steam on demand for main engines for the shaft. After the steam is used in the turbines, waste heat is removed from the steam in the heat exchangers called the main condensers. The steam is retuned to water, the water is fed back into the steam generators to start again.

cooling has to be dumped overboard at sometime or the sib would blow up like a balloon storing all that water

If your this clueless, give it up dude.

Only the heat has to be removed. That can be done through a series of heat exchangers with the surrounding seas the ultimate heat sink.

If you loose your heat sinks. The reactor scrams so heat production is stopped.

a reply to: neutronflux

nut there is still a net gain of heat and water can only cool so much and be cooled so much before it loses it efficiency as a coolant

or are you saying thermionic generators are now 100% efficient and take ALL the heat out of the water so that it turn back into a liquid?

WHY DOLAND BASED REACTORS HAVE COOLING TOWERS IF THEY CAN JUST CONVERT ALL THE HEAT ENERGY TO ELECTRICAL ENERGY?


seems like a huge waste