"I don't understand why six 'B-VIII uranium machines' are needed to generate electricity in series?" Female inventor Heidi Rama is very puzzled by the latest design blueprint.

"Mother of the Atomic Bomb" Lizer Metner gave a convincing answer: "Because of material limitations, in order to prevent the core from melting, the 'B-VIII uranium machine' cannot operate at full strength, so the output power of 5,000 kilowatts is the safe upper limit."

As the first generation of nuclear reactors, the "B-VIII uranium machine" belongs to the graphite water-cooled electric stack.

Graphite Reactor is one of nuclear fission reactors, and is also the most commonly used and used one. Graphite has good neutron reduction performance and was first used as a speed reducer in atomic reactors. Uranium-graphite reactors are a type of atomic reactors that are most commonly used: stack large cube graphite, insert nuclear fuel rods into it, and then start the reactor. In this way, the fast neutrons released after uranium 235 fission will be reduced by graphite, and then hit the new uranium 235 atomic nucleus, thus generating a chain reaction. Graphite reactors have the same principles as most nuclear power plants in other aspects, except that the speed reducer is different. Graphite and heavy water are recognized as the best speed reducer because these two reactors have high efficiency. The purity requirements for graphite used as atomic reactors are very high, and the impurity content should not exceed dozens of PPm (one in a million).

Graphite water-cooled graphitemoder-Atedreactor is a thermal neutron reactor (Thermal Neutron)

Reactor is a device that uses a slower agent to reduce the speed of fast neutrons to become thermal neutrons (or slow neutrons), and then uses thermal neutrons to carry out chain reactions. Since thermal neutrons are more likely to cause fission of uranium 235, a chain fission reaction can be obtained with a small amount of fission substance. The slower agent is some substances containing light elements and absorb few neutrons, such as heavy water, beryllium, graphite, water, etc. Thermal neutron stack generally arranges fuel elements regularly in the slower agent to form a core. The chain reaction is carried out in the core), graphite is a slower agent and water is a coolant. In the early stages of industrial development, graphite water-cooled stacks were mainly used to produce weapon charge plutonium, neon, etc. This reactor usually uses natural uranium metal components as fuel. The uranium 235 in the natural uranium in the reactor absorbs neutrons to produce nuclear fission reactions, releasing neutrons and energy. Some of these neutrons are used to maintain chain nuclear fission reactions, and some are

Uranium 238 in natural uranium is absorbed and converted into plutonium 239 and other plutonium isotopes. Pure graphite masonry is used as a moderator and reflector for graphite water-cooled stacks. There are two or three horizontal channels (horizontal stacks) or vertical channels (vertical stacks). Insert replaceable graphite casings into these channels, and an aluminum alloy process pipeline is inserted into the casing to separate cooling water from the graphite slowing agent. There are convex ribs on the inner wall of the process pipeline to maintain the process tube.

The gap between the channel and the fuel element. The temperature of each part of the graphite masonry is uneven. By changing the gap between the graphite sleeve and the process pipeline and the water flow in the process pipeline, the masonry temperature can be partially adjusted to make its temperature distribution flatter. Usually, the fuel element is made of rods with a diameter of about 35-38 mm and a length of about 100-200 mm. In order to increase the specific power and uniformly achieve the radial fuel consumption of the element, a tubular fuel element is also used.

In the early development of nuclear reactors, an open cooling mode was adopted. That is, the river flowed through the reactor core, and the heat-containing water would also be discharged into the river. Due to the large water consumption, high radioactivity level in the drainage, and prominent environmental protection problems, this method has been stopped and a closed cooling method is widely used, that is, the cooling water flows out of the core and the heat is output to the reactor. The heat is transmitted to the water on the other circuit side through the heat exchanger, and then returned to the reactor core through the main pump to form a closed cycle main cooling circuit or main circuit. There are two ways to treat the heat of the water in the first circuit: one is to exchange heat

The device transfers the heat from the first circuit to the second circuit water, and then cools it through cooling towers or river water to discharge the heat into the environment. Another method is to transfer the heat to the waste heat utilization system through a heat exchanger to provide heat to the outside world or as a heat source for power generation. An important feature of a natural uranium cold reactor is backup reactivity (the reactor supercritical positive reactivity value in the absence of any control poison. It is used to regulate power, compensate for negative reactivity coefficients, operating fuel consumption and accumulation of fission products, etc., and its size is very small related to the type of reactor, operating conditions and material change cycle).

The reactivity of early graphite water-cooled electric reactors increased with the increase of temperature, and the reactor power also increased (the so-called "positive temperature effect"), which led to an increase in reactivity until the reactor was placed under the control of an external neutron absorber (control rod, etc.), or caused serious accidents such as melting of the core. For example, in 1986, the graphite-tempered high-power tube reactor in Chernobyl, Ukraine was melted due to the sharp increase in power, causing a large amount of dangerous radioactive substances to be released into the environment. The Chernobyl nuclear accident was the first event classified as the most serious level seven in the International Nuclear Event Classification Table. After the Chernobyl nuclear accident, the issue of positive temperature effect attracted attention from all parties. As for the physical design of the reactor, negative temperature effects were obtained to ensure that the reactor has crucial self-stability.

The world's first commercially generated nuclear reactor was officially operated in Obinsk, Kaluga State, Russia on June 27, 1954, with an installed capacity of 5,000 kilowatts. It was named the "Atom Mirny" project. After half a century of safe operation, it was retired in April 2002 and was converted into a complex for research and commemoration.

The technology used by the "Peace Atomic Energy" project is most likely derived from the "B-VIII uranium machine" nuclear power technology obtained by the former Soviet Union from the Third Reich.

"I remember, this is not the power limit of the first generation nuclear reactor." Danielle, the chief casting assistant field girl, thought seriously.

"Right." The second casting assistant female secretary Anna Moffett, who did his homework, gave a Chinese experimental project that was later than the former Soviet Union's "Peace Atomic Energy".

The first atomic energy reactor in New China began to be built in May 1956 and officially started two years later. Its main purpose is to conduct scientific experiments and manufacture isotopes. It also uses uranium as fuel, heavy water as a slowing agent and thermal conducting agent, so it is called the "experimental heavy water reactor". Its construction is a sign that New China has entered the atomic energy era. The thermal power of this reactor is 7,000 to 10,000 kilowatts. The reactor operates normally after reconstruction, and the strengthening power is increased by 50% compared to before reconstruction. The maximum thermal neutron flux has more than doubled, and the irradiation space of the reactor has also increased by 2.6 times. Low-concentration uranium is still used as fuel.

"So, it's entirely possible for us to increase the output power of the 'B-VIII uranium machine' to 10,000 kilowatts or even higher." Female inventor Heidi Rama immediately grabbed the point: "Can we switch to more efficient coolant?"

Coolant (Heat-Carrying Agent), also known as "heat-carrying agent", is a medium that brings the energy released from the fission of the reactor core nuclear fuel from the reactor. In addition to meeting the general thermal and hydraulic properties, reactor coolant mainly requires a small thermal neutron absorption cross-section, weak induction radioactivity, good irradiation stability and good compatibility with reactor structural materials. Commonly used coolants for thermal neutron reactors include light water, heavy water, carbon dioxide, helium, etc. In reactors using liquid nuclear fuel or liquid slowing agents, nuclear fuel or slowing agents can also serve as the coolant of the core; reactors using solid nuclear fuel and solid slowing agents must use another coolant. The coolant must flow continuously through the core and take away the heat at any time to ensure that the core maintains a certain temperature and prevent the core from overheating or burning.

The "B-VIII uranium machine" uses heavy water with better nuclear characteristics but extremely expensive.

Historically, in order to prevent the Nazi nuclear program, the Allies carried out several targeted sabotage operations.

For example, "Heavy waterwar": In October 1942, in order to stop Germany's atomic bomb plan, the Allied Command led a secret military operation called "Heavy Water War". On February 27, 1943, the Allied assault team "Swallows" and "Gunners" successfully bombed the German Vimok heavy water production plant located in the Baren Mountains of Vimok Town, Norway. At the end of 1943, the Allied Air Force launched an air strike on the factory that resumed production, but it did not achieve results. The Germans then planned to relocate heavy water equipment and the heavy water stored in Vimok Chemical Plant to Germany. At 10:45 on February 20, 1944, the Allied commandos blew up the "Hedoro" ferry full of heavy water production equipment and materials on Lake Tinsjak, Norway.
Chapter completed!