To explore the development status and safety of nuclear power

Nuclear raw materials subject to the international market will restrict the development of China's nuclear power industry, so China set out to adopt the following methods to solve the problem of excessive dependence on uranium resources.

First, the use of new technology to search for uranium deposits;

Second, establish cooperation projects with countries rich in uranium resources;

Third, investment in overseas uranium mines;

Fourth, vigorously develop the fourth-generation nuclear power technology to reduce the demand for uranium resources.

Nuclear fuel cycle can improve the utilization rate of uranium resources, but our country's spent fuel reprocessing technology is not mature enough, the main solution is still off-reactor storage, and off-reactor storage capacity has tended to saturation, spent fuel processing will become a factor restricting the development of nuclear power in our country.

Nuclear fuel in the reactor by neutron bombardment nuclear reaction, after a certain period of time, nuclear fuel uranium content decreased, can not continue to maintain the nuclear reaction, discharged from the reactor. The discharged fuel is called spent fuel, which contains a large number of radioactive elements and is strongly radioactive, requiring strict handling procedures to ensure safety.

The spent fuel discharged from nuclear power plants contains 95 percent uranium (U-235 and U-238) and 1 percent plutonium, and after reprocessing, U-235 can be converted into fuel. The nuclear fuel cycle can increase the utilization rate of uranium resources by 30%.

However, China's reprocessing technology is not mature enough, and the operation cost is high, processing a ton of spent fuel to generate at least 45 tons of high-level waste, 150 tons of medium radioactive waste, 2,000 tons of low radioactive waste. Until 2021, the main solution for spent fuel is off-reactor storage.

The spent fuel produced by nuclear power plants is related to the plant equipment capacity, and the annual output of spent fuel is about 21 tons per 1 million kilowatts of nuclear power equipment capacity. It is estimated that in 2020, China's spent fuel production has reached 1,071.6 tons, while the spent fuel reprocessing capacity is only 50 tons, which cannot meet the processing demand.

According to China's nuclear power development plan, by 2030, nearly 2,000 tons of spent fuel will be generated every year, and the accumulated spent fuel will be about 24,000 tons, and the storage demand from the reactor will reach 15,000 tons. As of 2021, China has not yet formed reprocessing industrial capacity, and off-reactor storage capacity is also tending to saturation.

Spent fuel disposal will become an important factor restricting the development of nuclear power in China. The construction cost of spent fuel reprocessing plants is high and the construction period is long, with an average construction period of 10 years, so the demand for spent fuel treatment is difficult to meet in the short term.

Midstream analysis

Nuclear power equipment is the most expensive part of nuclear power plant investment and construction, and the degree of nuclear power autonomy mainly depends on the degree of nuclear power equipment autonomy. Among them, nuclear island equipment accounts for the highest proportion in the whole nuclear power equipment because of its technical characteristics.

Nuclear power equipment accounts for the highest cost in the construction of nuclear power plants, its proportion is as high as 50%, because nuclear power equipment is the most critical part of the nuclear power industry chain, and the degree of nuclear power autonomy mainly depends on the degree of nuclear power equipment autonomy.

The nuclear island cost accounted for the highest proportion of nuclear power equipment, reaching 58%, because the nuclear island process is complex, and the safety requirements are extremely high, and the key components in the nuclear island are monopolized by state-owned enterprises due to the high manufacturing process requirements.

After the marketization of nuclear secondary and tertiary equipment was opened in 2015, the price of conventional island and auxiliary system decreased significantly, and the cost ratio also decreased correspondingly.

The components of the nuclear island are fine and diverse, among which the reactor pressure vessel, the main pipeline, the heat exchanger and the steam generator are the three main components of the nuclear island.

The pressure vessel cost accounted for the highest proportion, reaching 23%, because the pressure vessel is the second barrier to prevent the escape of radioactive fission products, bearing an extremely important safety barrier role, so the quality standard of the pressure vessel is very strict, and the manufacturing cost is also high.

Nuclear grade valves are used in the nuclear island, but the cost proportion has gradually decreased, accounting for only 12% in 2019, and the decrease in cost is due to the improvement of the degree of localization of nuclear grade valves, and the price of domestic nuclear grade valves is only 11.5% of that of imported nuclear grade valves, and by 2021, the degree of localization of valves has reached 80%.