To explore the development status and safety of nuclear power

The nuclear island equipment manufacturing process is unchanged in the short term, and it is difficult to produce scale effects, so the price of nuclear island equipment will remain unchanged. The price of conventional island and auxiliary system has been adjusted in the short term after China announced the marketization of nuclear II and III in 2015, and the selling price and gross profit margin have been significantly reduced. In the period from 2018 to 2020, the price has basically remained stable, and the future is expected to have a small decline of about 3%.

The market share of nuclear power equipment can be obtained by calculating the investment in nuclear power plant construction and the proportion of nuclear power equipment in the cost of nuclear power construction.

Safety analysis of nuclear power equipment -- analysis of Chernobyl accident

The main causes of the Chernobyl accident were human error and the design defects of the nuclear power plant itself, and the defects of the Chernobyl nuclear power plant have been completely avoided in the design of the third generation nuclear power plant. The Chernobyl nuclear power plant accident occurred because of human error and the nuclear power plant's own design flaws.

After the power dropped rapidly to 30MWt, a large amount of xenon gas appeared inside the reactor, and xenon gas and water absorbed a large amount of neutrons, making it difficult to increase the reactor power in a short time. In order to reach the power required for the test as soon as possible, the operator shut down the automatic control system and pulled out almost all the control rods. At this time, the reactor core reaches the prompt critical, the power rises rapidly and breaks through the rated power, and the reactor temperature is too high, resulting in a steam explosion. After the explosion, the graphite contacts with the air to produce hydrogen, and a secondary explosion occurs.

There are two flaws in the plant's design.

The front section of the RBMK control rod is made of graphite, and when it is completely removed from the core, it is lowered into the core to provide a small increase in reactor power before normal power reduction.

So the SCram button doesn't shut down the reactor it accelerates the reactor power rise; At the same time Chernobyl used a positive void coefficient, and as the space occupied by steam in the core increased (boiling increased) the fission reaction also accelerated (reactor power increased) after the RBMK reactor accident.

Safety analysis of nuclear power equipment -- analysis of Fukushima nuclear Power Plant accident

The Fukushima nuclear power plant delayed the optimal emergency repair time, resulting in excessive temperatures in the pressure vessel and melting fuel rods. Zirconium wrapped around the fuel rods came into contact with water and produced hydrogen, triggering the explosion.

Immediately after the tsunami in Fukushima, Japan, workers inserted control rods into the core material to shut it down, but the condensing system needed to keep operating because there was still residual heat in the core after the shutdown, and the core fuel would decay and continue to release heat, and the core would take several days to completely cool

However, the external network of the Fukushima nuclear power plant was destroyed, the condensation system lost power supply and could not work, and the nuclear power operation system was in an unbalanced state. Without an engine to drive the pumps to condense the water over and over again, the heat in the pressure vessel will continue to rise, eventually melting the fuel in the core.

The fuel in the core is coated with zirconium. When the fuel gets too hot, the zirconium flows into the water and causes an oxidation reaction to release hydrogen, which accumulates and causes an explosion. Only after the explosion did workers begin pumping seawater into the reactor to cool its core.

In the Fukushima nuclear power plant accident in Japan, earthquake and tsunami are only the fuses, and human factors are the main reasons.

The emergency measures prepared by Tokyo Electric Power after the external network was cut off were not sufficient, and after the battery maintained the condensation system for 8 hours, the generator power was not provided in time, and after the temperature in the reactor was too high, the seawater was not injected into the reactor in time for cost reasons, delaying the ordinary accident to a level 7 nuclear accident.

China has formulated strict management measures for the operation of nuclear power plants, conducted safety training for nuclear power plant personnel, and responded to accidents in a timely manner to avoid major nuclear accidents caused by human factors.