Questions_and

Question 3. High pressure steam leaking into salt loops. Radioactivity outside containment cell.

Your new site drawing looks good to me Jim.

The only thing I can see is that any leak from the high pressure water side into the molten salts might be a problem. Also the large dump tanks underneath the water/salt exchangers are on land and would be a contamination source, but hopefully they would be fully contained. Too bad that all the dump tanks couldn't be on the barge.

Keep up the good work.

David

Hi David,

You have a good understanding of how the system works. You come up to speed fast!

RADIOACTIVITY CONTAINMENT ISSUE: The first cooling loop salt contains everything that is radioactive. All radioactivity is completely contained inside the blue containment cell.

Molten salt reactor salts do not become radioactive or altered in any way through exposure to radiation. That is a major reason they can be used in molten salt reactors. The nuclear material - uranium, plutonium, or thorium - they all work well - are chemically prepared as dissolved salts themselves and mixed into clear salt to make fuel salt. In a similar manner, the radioactive materials are later chemically precipitated to remove them, along with fission products, from the clear salt.

According to one paper on the subject, the clear salt being used as fuel salt can be recycled for hundreds of years. Fission product gasses, such as xenon-135, are naturally centrifuged out in the circulating pump bells where they are picked up and sent via pipes to a gas handling system (pink box on underside of containment cell ceiling) to collect them.

So the secondary salt will not become radioactive through exposure to radiation from the primary fuel salt in the first heat exchanger and carry radioactivity outside the containment cell.

Again, secondary and tertiary salt loops are ordinary so-called "Clear Salt" and do not present any hazard. Since all leaked salt will immediately cool and harden into lumps like lava, any salt leaked outside the barge will not soak into the ground or flow into drains to create an environmental hazard. This is often the case in today's "not-so-new" solid fuel reactors where cooling water, often made radioactive through intimate exposure to highly radioactive fuel rods, later leaks into the ground via leaky pipes and then finds its way into outside aquifers being used for drinking water.

Only the leakage (or spill tank, white insert) and reactor dump tank on the barge would ever hold radioactive fuel salt. The reactor's dump tank also has both a passive heat exchanger (yellow lines) and barium rods (green lines) - the same material as the reactor's control rods - to squelch residual fission and to remove any residual fuel salt decay heat.

The other dump tanks are there as a place to store the clear salt during maintenance shut downs. All dump tanks have re-start capability. After a shut-down, small gas-fired package heaters would re-melt the salt in the tanks and small nichrome wire heated pipe-fill pumps would refill the pipes with hot melted salt. Nichrome heating wire (also found in cooking ranges, toasters, and electric blankets) is also wrapped around the pipes and control valves to preheat them for the return of the molten salt.

Salt storage tanks for maintenance is standard design world-wide these days for the large amounts of heat transfer salts used in those huge solar heat collector systems being built in deserts. I took the maintenance tank idea off the web site of a chemical company that supplies heat transfer salts.

Amazingly, a company called "FlowServ" makes huge water cooled, corrosion resistant, heat transfer salt pumps for industry that should work here (black squares above reactor ceiling). I think if I were to build a molten salt reactor today, all I would have to fabricate would be a reactor tank made of Hasteloy-N. The rest (except for the starter uranium) could be purchased. Uranium is a government-controlled substance, like alcohol.

For the same power, these very simple molten salt reactors should cost a tiny fraction of today's huge and complicated solid fuel reactors.

WATER LEAKAGE ISSUE: After many years of use and vibration, it would be reasonable to think high pressure water could eventually leak into the unpressurized third salt loop - probably at the top of the superheater - and burst either the superheater shell or the shell of the second heat exchanger. To cope with that very real likelihood, there are two blowout reliefs - simple rupture diaphragms - on the salt lines between the third heat exchanger and the steam generators.

There is also a single blowout relief in the second loop to protect the shell of the first heat exchanger and another blowout relief at the highest pressure point (circulating pump discharge) in the primary loop to protect the reactor vessel itself.

Since this is non-radioactive clear salt, no special haz-mat clean-up would be needed to pick up the lumps of salt that leaked out.

Your question prompted me to review my drawing and I realized I had failed to add an inerting gas cascade note - helium - which I immediately did. This is a way a computer could detect that something was leaking between salt loops somewhere due to a pressure going too low or too high. The pressure cascade would drive any salt leakage toward the containment cell - the safest thing to do.

Thank you for checking out the design.

Jim Holm

Question 4. Comments about the prototype reactor barge. (From another engineer also named David.)

Hi David,

Really appreciate comments from a engineer.

I like everything on the barge. Some comments:

1,300 F is on wrong pipe. I think my colors are misleading. I'll make the hotter pipes red and send it to you again.

Where is make up water system? There is no water in this system. The combustor normally used in the jet engine has been replaced with a heat exchanger to expand the air as it passes through the jet engine.

This is how they made nuclear jet engines work in the 50s. The reactor was carried in one of the two bomb bays. Bomb bays on the B-36 were as big as box cars.

This jet engine works on steam instead of combustion gases so the normal 5,000 life of a jet engine should be longer. There is no steam involved. Typical natural gas combustion turbines like the three at Big Bend are getting about 10 years or 100,000 hours.

Since thorium fuel is cheap the heat in the exhaust needn't be recovered. Right? This barge is a test prototype. Its reactor is 40 times smaller than a usual reactor. The generator is only 25 megaWatts and I'm keeping everything as simple as possible.

It will be taken first to an uninhabited remote island in the South Pacific for testing.

If it passes all the tests, it will be loaned to a village on a different remote island for a practical power run. (I got this idea from Toshiba's Galena, Alaska, offer.) The intent is that the people on the island will not have to know any more about running the barge than running their diesel generator. Their diesel will be kept as a stand-by. Recorders on the barge will keep a log of how it performs.

This type of reactor has 30 year power runs and then needs a rebuild. When it is rebuild time, the reactor is towed back to the factory where the liquid salt is purified of waste and the reactor's worn out graphite rods are replaced. Then it is good to go for another 30 years.

Do the Russians/Chinese already have one of these? China began a formal thorium reactor development program last year. I know how to contact them but don't know who to contact at this time.

The Russians have been building nuclear power barges for remote Siberian mines on the Arctic Ocean coast for several years. Russian power barges use two of their small icebreaker nuclear reactors. By a strange coincidence, their reactors are about the same power as my prototype reactor.

Thanks for the comments.

Jim Holm

http://www.coal2thorium.com

I should have mentioned that this system is called "Externally Fired Gas Turbine" and is how coal, sawdust, and other rough fuels are used to drive a gas turbine. I attached a drawing of the process. The reactor is the "burner" in this case.

The air sucked into the turbine would be ambient at 70F, if the heat exchanger worked well, the air's temperature coming out of the heat exchanger might be 1,200F. So there could be a 1,130F temperature rise.

The molten salt going into the heat exchanger would be 1,300F and coming out 1,025F for a 275F drop.

There will be a small rise in the air's temperature going into the heat exchanger due to the heat of the intake blower's compression and a lot of heat energy loss due to the exhaust turbine. Will be lucky if this turbine-generator system is 25% efficient.

Power generation combustion turbines are single shaft, slower, and proportioned differently than jet airplane turbines.

Most commercial jet airplane turbines these days have dual co-axial shafts with a fast shaft for combustion and a slow shaft for the by-pass fan. There are very few pure jet engines around. Even the small engines on Upjohn's Gulfstream were by-pass. That's where that huge ring at the front of a large commercial jet engine is doing its thing by creating a ducted fan.

Molten salt carries heat about the same as water.

----- Original Message -----

Thanks Jim for your excellent explanation.

Can enough energy be added to the air with a 275f salt/air heat exchanger to drive the turbines? Based on my poor memory of thermo, the pressure rise of inlet air at 75f and 15psia when heated 275f in a closed volume would only be about 5psig.

In a message dated 8/5/2011 10:10:54 P.M. Eastern Daylight Time, JimMarilynHolm@charter.net writes:

Hi David,

The liquid loops are solid salts made hot enough to be melted into a water-like liquid. Think about the bags of dry salt you get for a water softener. You can melt it in a very hot pan. Salt at these temperatures - about 1,000F - has no vapor pressure at all so the entire system has no pressure. It is totally incapable of any kind of steam and thus incapable of any kind of explosion - steam or otherwise - nothing inflammable involved. The particular salts used are totally immune to the effects of radioactivity - there is no water involved so the salts cannot pick up radioactivity like water does - so should remain good and useable forever.

Once the reactor is up and running, an almost trace amount of metallic thorium powder is dissolved into the liquid salt used in the reactor salt loop - the thorium in the molten salt will become radioactive - so this salt is called "Fuel Salt." As the melted salt carrying thorium passes near the black graphite rods in the reactor, a bit of the dissolved thorium fissions in a two-step nuclear reaction, making the salt hotter. The hot, and radioactive, melted salt is then circulated through the heat exchanger to transfer the heat to a second loop of melted salt - called clear salt - that is not radioactive. This is the liquid loop that carries the heat to the liquid-to-air heat exchanger in the modified jet engine.

A small amount of dissolved enriched uranium salt is used to start things but is soon used up and replaced by thorium. You could switch to some other nuclear fuel later. Molten salt reactors will run on anything radioactive - uranium, plutonium, MOX from warheads, nuclear waste from conventional reactors. None make the reactor difficult to handle but each has its own personality. The French have identified one "Cocktail Combination" that should be avoided.

The two-step process of turning non-radioactive thorium-232 into radioactive uranium-233 takes almost a month. This makes it useless for weapons. At any one time only a tiny bit is fissioning but more is constantly being made so, once started over a month or so, the process just keeps rolling along. One thing that must not happen is stopping the reactor completely for any length of time. Then a full re-start might be needed. The control rods will bring it down to a warm idle at very low energy that should last for decades on whatever happens to be dissolved in the fuel salt.

The amount of dissolved thorium is so slight you can keep the reactor going thirty years by adding a bit of thorium as needed. After thirty years, the tiny amount of waste material that does accumulate in the salt has to be precipitated out or the reactor will stop running completely.

All radioactivity stays inside the radiation confinement cell (colored blue).

The tiny blue dots at the bottom of both the primary and secondary molten salt loops are "Freeze Plugs." They are kept frozen by small cooling fans. If electricity is lost, the Freeze Plugs melt and the salt drains into the blue drain tanks below. If, for some reason the salt loops get too hot, the heat will overpower the fans and the freeze plugs will melt even if the cooling fans are running. There is no way to stop this natural draining safety process if the reactor gets too hot.

When the salt drains away from the reactor tank into the blue drain tank, it is away from the graphite rods and stops fissioning, eventually growing cold enough to turn solid. If, for some reason there is a leak, the leaked salt cools and turns solid almost immediately into solid lumps that look like lava rocks. This means that any radioactive leak can be shoveled up like rocks rather than soaking into the ground like the radioactive water from conventional water-cooled reactors.

There are three separate drain tanks. One for the reactor's fuel salt loop, one for the clear salt loop, and one for a drain in the reactor cell's floor to catch any pump leaks, etc. The drain tanks have propane gas heaters to re-melt the salt so it can be returned via little pumps to the loop pipes. Devices like pumps and control valves are kept hot by being wrapped with nichrome heating wire (like the wires in toasters and electric kitchen ranges).

Again, there is no steam. In fact, no pressure at all in any part of the entire system. In my design, I add a small amount of deliberate pressure to each loop using inert helium gas. The reactor loop gets 5 psig, the second loop gets 25 psig, and if there is a third loop, it gets 50 psig. Two things are accomplished by doing this. First, by using a computer to monitor the pressures any leaks between the loops can be quickly detected and the location of the leaking interface immediately figured out. Second, by cascading the pressures, any leak will force clear salt toward the reactor loop, thus keeping radioactive salt from getting outside the confinement cell via the clear salt loops.

Corrosion at these temperatures is a terrible problem. Corrosion-proof high temperature industrial plastics are used where ever possible instead of metal. An expensive special corrosion and radiation proof metal called Hastelloy-N seems to have dealt with these problems. Also a metal called INOR-8 was used in the early days of nuclear airplanes.

Heat transfer salt has been used for over 100 years in some industries such as metal foundries. These days similar salts are used in large solar heat collection systems in Spain and North Africa and a company called "FlowServ" sells heat salt circulating pumps on the internet at very reasonable prices.

If you notice, EBASCO designed the confinement cell in such a way that the motors for the circulating pumps are outside the hot cell. This extends their life and makes replacement a non-radioactive task.

A company called "Coastal Chemicals" sells a heat transfer salt called "HITEC" on the internet these days. I use HITEC for my third loop.

As Mark Twain used to write, "I didn't have time for a short note so I wrote a long one."

Hope this provokes more questions. Molten salt reactors are very different animals than your neighborhood reactor but many are beginning to understand how dangerous something full of high pressure radioactive steam is.

I added a slide about the ultra-secret nuclear airplane project.

Regards,

Jim Holm

http://www.coal2thorium.com

----- Original Message -----

Hi Jim. Is thorium a gas at 1350f and does it act like steam? What kind of corrosive properties would it have?

D

In a message dated 8/5/2011 12:02:57 P.M. Eastern Daylight Time, JimMarilynHolm@charter.net writes:

Hi David,

As per your comments,

I reversed the colors on the secondary cooling loop

Marilyn gave the drawing a more accurate name

I added a few additional labels

Thanks again for the comments.

Regards,

Jim Holm

http://www.coal2thorium.com

Thanks Jim for your excellent explanation.