Energy From Thorium Discussion Forum

How much would it cost to make floating power plant both storm proof and tsunami proof? One of the big advantages of being underwater is that the environment is very still. No storms, waves, or crashing airplanes.
The challenge is to achieve sufficiently high reliability and remote operations to make underwater deployments economical. My bet is that over time the cost of making the power plant sufficiently reliable and capable for remote operations will decrease steadily while the cost of physical protection will increase. Hence underwater deployments are a reasonable future for power plants.

Storms can overwhelm any man made construction. This fact will result in extremely high insurance costs as well as very bad public relations problems.

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Underwater deployment of the heat production component of the reactor, the reactor core and heat exchangers and associated pipes and pumps, in short, anything that is radioactive is cost effective.

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If I understand your previous posts, the nuclear reaction in the Lftr is self regulating and needs little control. The component of the reactor complex that requires the attention is the part that generates the electric power. That part is on the land.

You all are missing the point. Most of our old coal fired power plants are on or near the water. These plants can be converted to nuclear cheaply. These converted plants could be operated and controlled just like the pre-converted coal plants were at almost no cost impact to the nuclear conversion.

Using a buffered molten salt interface fed by an inexpensive molten salt pipeline and storage tank(s) with associated heat control that exactly match the temperature requirements of the old power turbines, all the old power production turbines could still be salvaged and reused.


Most coal fired power plants are on the water. Dredge a proper size hole (100 meters) in the river or sea bed, install the reactor core and you are good to go.

What would a 1 GW Lftr nuclear core cost to produce; not much.

The MSRE wasn't even a prototype. It was an experiment. We have a lot of work to do before we are ready for underwater deployment. Yes the reactor feedback for short to modest term (less than hours) response is pretty self-regulating. However, there are MANY things about the reactor core which are not self-regulating and require active controls. These include:
1) the addition of more fertile,
2) transfer of fissile from the blanket to the core,
3) maintaining the chemical balance so that we do not have fluorine to corrode the walls,
4) extracting the noble metals from the fuel salt
5) extracting the fissile from the blanket
6) storage of off gases
7) maintenance of the pumps
8) inspection of walls, HX, pumps, etc.
and many, many more I'm sure. We need to build land based units first, debug these systems and get them to a state where we can afford to significant increase the cost of physical access to the plant (underwater deployment) since we are so reliable that the probability of requiring physical access is low.

Yes, Lars, but many of these things are continuous-flow operations in a very hard radiation field. They're not activities that involve any human touch labor--they're activities that involve eyeballs on computer monitors. An underwater reactor doesn't mean an unmonitored reactor. It's just that those eyeballs would be looking at a monitor on the other end of an ethernet connection to the reactor.

True so I expect the remote control portion is required whether on land or sea.
But if a pipe clogs (like happened a few times with MSRE) we may be required to send in a robot to cut out and replace a piece of piping. If we anticipate the event and include spare piping and the robot then it doesn't matter whether we are on land or sea. But if we need to make a new pipe and bring it to the reactor, or make a new robot to do the cutting these things are easier on land. So, my comment is that gaining the operational experience to know what we need and to reduce the unplanned maintanence actions are better done on land initially.

If you have a repair event of that magnitude you tow the reactor back to the maintenance facility and tow another reactor out there to replace it. Odds are you never bring the same reactor back to that site again--it goes somewhere else. But to the customer, the particular reactor carrying the load is of no particular consequence, so long as it works.

After we have 50 reactor years experience on land then we can launch to sea.
Towing back to the land means a long outage time with lots of visibility. We don't want that for early reactors.

The first power reactor ever built was a portable underwater reactor. It got moved back and forth and worked quite well.

http://en.wikipedia.org/wiki/S1W_reactor

Producing the nuclear heat underwater, and transfer it to land by a salt pipeline is not an idea that struck me immediately. I still think in terms of underwater nuclear plant to mean away from population. It could all be underwater with only power cable coming out and a remote controlled operation or on a barge with operators able to access it, rather like the Russian floating power stations under construction. I guess keeping only the reactor (heat source) underwater as a protection from radiation or against a Loss Of Cooling Accident is an option but I do not think of it as an underwater powerplant. However I agree that it keeps all the options of employment open.

IMHO, in the United States of America and in Great Britain the low impact retrofitting of old coal fired power plants will be by far the most attractive mode of deployment for the Lftr.

These power plants are universally close to population centers and are on bodies of water to support their large evaporative cooling towers for their turbines. This mode of Lftr deployment will be the most cost effective and therefore the most desired Lftr application for the utilities in these countries.

First, the utilities will save billions by keeping both the existing coal fired plant infrastructure and their current electrical grid connectivity.

Second, no nuclear produced heat is released to the collocated river. This will meet the requirements of state regulators to minimize heat pollution of these rivers.

Because there is no heat release by the Lftr into the water, the reactor can be sited in the quite waters of a deep protected lagoon that is out of the rivers flow. The old coal plant cooling towers provide reject heat dissipation for the power turbines.




If the Lftr core can be designed small enough, and I think it can; say 20 meters long by 8 meters in diameter, then the reactor core can be disconnected from the dump tanks, lifted out of the water, and placed on a barge or railroad car for transport back to the depot for repair or decommissioning. A spare core could be stored on site at the coal plant for fast replacement. The dump tanks can remain under water where they store the molten salt. Once the new core is lifted back into the water and reattached to the dump tanks along with the other various reactor connections, the molten core salt can be pumped back into the core, and the plant can resume operation. Speed and preplanning are of the essence here. During the few days that this maintenance action is underway, the large molten salt storage tanks could provide uninterrupted electrical production.

More broadly, a coal fired power plant is not place where the repair of the reactor core should be undertaken; the depot located on the sea shore where the skilled personnel and specialized equipment are located is the right location for this repair function to occur.

The reactor core should be constructed of low activation material to facilitate transportation and maintenance. See the figure below for a representation of the Lftr with molten salt storage.

I'd much rather move the repair staff and equipment to the reactor than the other way around at least for land based deployments. Eventually we will understand the repair requirements well enough to equip the reactors with parts and robotics to handle the vast majority of repairs under remote control.

Let me get specific--I think an excellent site for the "manufacturing/maintenance/serious-reprocessing" site for LFTR would be at the confluence of the Tennessee River and Tenn-Tom waterway in northeastern Mississippi. This is the same site where the Yellow Creek reactor was being built, so it's no "greenfield" site. There's certainly some environmental impact statement written for the site out there somewhere.

If LFTRs were built and deployed from the Yellow Creek site, they could go up and down the TN River and replace TVA coal plants all along the river. They could also go down the Tenn-Tom and into the Gulf of Mexico and replace coal plants on the Gulf coast from Texas to Florida and even into the Caribbean.

I'm told that the state of MS would actively support any effort that brought jobs and development to the Yellow Creek site.

In any repair activity of heavy equipment, it is cost effective to move the failed unit to a centralize repair facility, then to move the repair service to the unit. As an example, trucks, railroad locomotives and ships are moved to centralized repair yards; they are not repaired on site.

A specialize building at hundreds of coal plants would need to be built to house the reactor core repair function. It is more cost effective to centralize the repair function to minimize the total systems cost. For example, specialized equipment like robotic laser welders and specialized high powered weld x-ray inspection equipment may be impractical and too delicate to move from site to site.

I guess this depends on the complexity of the repair equipment. I'm picturing a robotic arm like the video shown in another thread to fix a CANDU. I'm guessing we will have to replace HX, clogged pipe sections in the vacuum distiller, the fluorinator vessel due to corrosion, etc. Thus I'm picturing welding a subsystem replacement in place w/o moving the reactor. The MSBR design had space for storing "spent" HXs etc. presuming they were hot and it was desirable to keep them inside the reactor. I could picture an underwater deployment being shipped with a spare couple of HXs and the capability to swap them out by remote control without having to bring the reactor to the surface.

I think that submersible reactors would be kept VERY close to shore in riverine environments (<100m) and probably rather close to shore in coastal environments (< 2 km).

The reprocessing scheme I envison on board the submersible is fluorination of the blanket and reduction into the core salt. I would leave all core salt distillation operations back at the manufacturing/maintenance site.

The reactor would be designed to run for 2-3 years between return to the M&M site. The interval should be chosen so as to make the operational duration similar to the time period needed between turbine overhauls.