We are in the basement of EBR-1. This door blocks radiation and access to the room below the reactor pressure vessel. The vessel was hanging from the thick floor above with a lot of space around it. This room contains a lifting table on which the reflecting cup was placed. The table was mounted on a hefty hydraulic cylinder which could lift up to the bottom of the vessel.
This room is quite complex, but with no light and 2 foot thick window, I did not get a pic. There are two other rooms connected to it with thick electric moved doors between them. A rolling electric hoist could move from room to room through those doors. Once the reactor was critical no one could enter this room. The reflector cup was about 3 feet in diameter and 3 feet tall with 1 foot thick walls made from small yet heavy blocks of depleted U-238.
This is a Fast Neutron Reactor and was not controlled like a slow neutron reactor is with neutron capturing rods. This reactor relies on a neutron source and a reflector to effectively create critical mass. It is safer as if the core is left alone it will quit and cool down. That is a genius design as it makes it 100% safe and vastly reduces waste products. So the cup must surround the core for it to be critical, that is why the cup is on top of a hydraulic jack, release the pressure and the ten ton cup will glide quickly to the floor. That is how the SCRAM is so simple and fool proof.
|Turntable in cup repair room|
Slowly the cup itself would turn into Pu 239 and Pu 240. The isotope 240 is radioactive with a short half life, if enough collects it could go critical on it's own. It should be clear why the reflector was made of blocks and two rooms were built to replace all the U-238 in the cup on a regular basis.
The cup repair room is quite interesting and still somewhat of a mystery to me how they moved the heavy cup between rooms. We met a worker from the day on our first visit, but he did not know how it was done as he worked the top side of the reactor. This time we got no help. A good reason to return for more looking and thinking. There are rolling hoists with electric slip wires and it appears they could travel through the door. It is the how it was done that puzzles us.
The transport hoist was controlled by this panel in an area safe from radiation.
So now it is time to move on to reactor cooling or heat recovery. We know NAK the heavy corrosive liquid metal was fed into the core at the bottom in a low temp state and rose inside the core to exit the top very hot cooling the core. The hot NAK flowed to a heat exchanger where the heat transferred to NAK loop 2, This was done to allow only a small amount of NAK to be in contact with the reactor pressure vessel and fuel core. After the exchange of heat, the NAK went into a receiver tank before being pumped by magnetism back into the gravity flow tank above and behind the top of the reactor.
Now that we have left the reactor and all radiation behind, NAK loop 2 is just as hot and travels to an NAK to H2o Steam Super Heater then to an NAK to H2o Steam Boiler and then to an NAK to H2o Feed Water Economizer.
|Economizer warms feed water|
This flow removes heat from the NAK loop 2 and now it is at it's coolest point.
|Mud Tank and vertical boiler tubes The Steam Drum is on top|
This turns the feed water into wet steam
It now flows downhill into the receiving tank and from there is magnetically pumped back to the heat exchanger to get hot again. There is a drain tank just like the primary system has that will hold the entire amount of NAK in the system, they are both located in pits below the basement level.
|Super Heater makes dry steam|
Now that we have left the NAK behind we have dry superheated steam. It can take two paths, one is through a steam turbine to make mechanical energy or the other is directly into a condenser to become feed water again. That brings me to feed water. It is special stuff, super pure and clean, no minerals etc to scale up a boiler or destroy a turbine. Condensor water is just plain drinking water and makes a loop outside to fan cooling radiators and is pumped back nice and cool to the condenser.
|Condensor instantly turns steam into feed water|
As the steam came to the turbine it was throttled to allow a slow start and then maintain a constant speed of the turbine. Anyone who knows more about this 1940's single pass steam turbine please leave a comment.
|Steam Turbine Governor end and feed pipes|
|Closeup of speed control|
This turns the dry steam into a rotational mechanical energy. The shaft of the turbine spins very fast and then enters a gear speed reduction unit built by Murray. The output from the Murray unit is 1200 RPM. The Generator connects to the 1200 RPM shaft and is rated at 300KW. It has a DC voltage exciter on the end of the shaft.
The small electric motor drives an oil pump that lubricates the gear speed reduction unit.
The much cooler wet steam exited the turbine through the bottom and went into the condenser under the floor to be made back into feed water again.
So now you know this is the first place on Earth that splitting atoms created electrical energy and powered the first town in the USA, ARCO Idaho.
ARCO was powered in 1954 from Borax III.
There is a story with that also, told to us a few years back by a volunteer at this site. He had worked as an electrician during that time on this site. As I recall it somewhat like the space program, they got a man in space and told the President and then he said we are going to the Moon.
These guys were rushed and got 4 light bulbs powered by the exciter output. That got to the President and he went to make a world announcement that they had powered up a town.
They had to pay dearly to have the wires and poles etc run to the closest town ASAP and that is how ARCO got the first atomic power. Pure Politics.
Now, this was not the first reactor by a long shot. The USA had at least 8 in weapons production and Russia had them and England and back in the day, Germany did have one. They were all slow neutron reactors as are all USA power plants, most being Westinghouse AP-1000 units.
EBR II was a self-contained fuel recycling plant. A neat concept that worked. Once loaded with weapons grade Pu-239 and a blanket of depleted U-238. It could run for years and years with no possibility of blowing up or melting down. The waste from it was minimal. It really was the perfect power answer, but two things killed it. Westinghouse lobbyists and the question, who could be trusted with a power plant that ran on and produced more weapons grade Plutonium. We could have had almost free electricity for hundreds of years.
Someone in France thought it was a good idea and they have been selling slightly enriched fuel for slow neutron reactors around the world for many years. Just like drug dealers, they cut their Pu-239 with U-238. MOX made at Tricastin.
Russia has had a BN-600 and BN-800 Fast Neutron Sodium cooled Breeder reactors running for 30 years now. Kinda a copy of EBR-II.
Note: A good tour from a Technician who worked this site.