China Mass Production of Nuclear Thermal Power Could Reach 1 Cent per KWH

The analyzed costs for the DHR-400 (deep pool reactors) are in the range of 1.65 cents per kilowatt-hour. The costs are 30-40 yuan ($4.58-6.1) for a gigajoule of heat (277.8 kwh). This is close to the one-cent target of the Anthropocene Institute. China is planning to build a lot of nuclear regular third-generation nuclear reactors and drive costs down by 40%. Learning to build Nth reactors cheaper could drive the costs of deep pool reactors to 1 cent per kilowatt-hour. Mass production and process improvements could then bring this solution to the one-cent per kwh target.

The cost projection is for a kilowatt-hour of thermal power but this heat can displace a large usage of coal. There is also a projection that China could mass-produce regular nuclear reactors for electrical power. The projection is that they could reduce costs by 40% from today’s costs. This would get nuclear electric costs in 2030 to potentially less than 3 cents per kwh for electricity.

In 2014, the levelized cost of electricity (LCOE) in China was 4 cents per kwh for hydroelectric and other renewable energy (RE) power had costs ranging from 5 to 11 cents per kwh.

The nuclear district heaters will already be near the cost of traditional coal-fired boilers in China and around 40 percent of the cost to produce the same amount using a gas-fired boiler. China is not importing enough natural gas from Russia and other sources. A trade deal with the US would likely involve a lot of liquified natural gas which is more expensive.

About 60 pool nuclear reactors have already been operating at Universities in North America and Europe for decades in undergrad programs.

China will more than double its current nuclear power by adding deep pool nuclear reactors for heating.

CNNC, CGN and SPIC have announced concepts for low-temperature district heating reactors. Development of these acknowledges the role of heating in air pollution, particularly PM2.5 particulates, which are reported to be more than ten times higher in winter.

CGN – The NHR200-II reactor is a low-temperature district heating reactor. Its design is described by CGN as “mature”, having passed the National Nuclear Safety Administration review in the 1990s. In February 2018 it was announced that CGN and Tsinghua University were carrying out a feasibility study on constructing China’s first district heating nuclear plant using the NHR200-II design.

CNNC – The District Heating Reactor-400 (DHR-400) or ‘Yanlong’ is a low-temperature 400 MW pool-type reactor. It is designed to provide heat at 90°C for up to 200,000 three-bedroom apartments. The reactor prototype achieved 168 hours of continuous heat supply in November 2017 – seen by its developers, CNNC, as the first major step towards commercialization of the design.

SPIC – The Advanced Happy200 is similar to the Yanlong, 200 MW and producing hot water at 110°C. Pre-feasibility studies suggest first commissioning in 2022.

District Heating of Northern Chinese Cities

China’s government agencies, the National Development and Reform Commission (NDRC) and the National Energy Administration have announced a five-year plan to convert 70% of northern cities to mostly natural gas heating instead of coal.

The government has made “concrete arrangements” regarding geothermal heating, biomass heating, solar heating, gas heating, electric heating, industrial waste heating, and clean coal-fired central heating.

Half of northern China should be converted to clean heating by 2019, reducing bulk coal burning by 74 million tonnes, the reports said. That reduction should reach 150 million tonnes by 2021.

The launch of Yanlong is the first step of CNNC’s ambitious plan to boost nuclear heating in north China in the coming years. The organization expects to build pilot nuclear-fired boilers by 2018 before putting them into commercial operation after 2020. (Beijing Review)

A 400-megawatt nuclear heating reactor can generate as much heat per year as the burning of 320,000 tons of coal or 160 million cubic meters of natural gas, and Yanlong releases no carbon dioxide or dust into the air. Yanlong, if used as an alternative to coal-fired or gas-fired boilers of the same supply capacity, will reduce emissions of carbon dioxide by 640,000 tons or 204,600 tons per year.

District heating is fairly common in Northern Europe and Russia.

District heating systems can vary in size. Some systems cover entire cities such as Stockholm or Flensburg, using a network of large 1000 mm diameter primary pipes linked to secondary pipes – 200 mm diameter perhaps, which in turn link to tertiary pipes of perhaps 25 mm diameter which might connect to 10 to 50 houses.

The first DH system in Sweden was in operation in 1948, but the more rapid build-up of these systems started in the 1960s. Now virtually all Swedish towns have a DH system. District heating accounted for 86% and 69%, respectively, of the energy use for heating
of multi-dwelling buildings and non-residential premises, while the corresponding proportion was 10% in one- and two-dwelling buildings Total DH production in 2007 amounted to 56.3 TWh (47.5 TWh was delivered) and was dominated by biomass, which accounted for 44% of the production.

Conventional Nuclear Reactors Will Reach 13000 yuan/KW by 2030

Sanmen plant in Zhejing is the first project in China to adopt AP1000 technology, and was commissioned in 2015. The unit investment cost of the first AP1000 reactor is 21,000 yuan/KW. With accumulated experience in equipment building and construction, the unit investment cost of subsequent reactors will gradually lower to 15,000 yuan/KW.

“Hualong 1” is the integration of ACP1000 and ACPR1000+ designs. On 25 May 2017, the first demonstration project of “Hualong 1” in the world, Fuqing nuclear power V unit, was successfully performed. According to field survey, the unit investment cost of the first reactor is 20,000 yuan/KW, and follow-up reactors will lower to 17,000 yuan/KW.

With learning by research and learning by doing, investment cost of third-generation nuclear technology will continue to go down. The unit investment could decrease to 13,000 yuan/KW by 2030. Several factors contribute to cost reduction. The first is improvement in localization level driven by the batch construction, which will reduce the cost of key equipment as steam generator, the regulator and the main pump quickly. The second is standardization promoted by batch construction will drive down cost. The third is cost reduction of design fee and technology transfer fee. The fourth is active learning in early projects to shorten construction time. Finally, with scale effect, the unit investment cost comes down.

District heating is fairly common in Northern Europe and Russia.

District heating systems can vary in size. Some systems cover entire cities such as Stockholm or Flensburg, using a network of large 1000 mm diameter primary pipes linked to secondary pipes – 200 mm diameter perhaps, which in turn link to tertiary pipes of perhaps 25 mm diameter which might connect to 10 to 50 houses.

The first DH system in Sweden was in operation in 1948, but the more rapid build-up of
these systems started in the 1960s. Now virtually all Swedish towns have a DH system.
District heating accounted for 86% and 69%, respectively, of the energy use for heating
of multi-dwelling buildings and non-residential premises, while the corresponding proportion
was 10% in one- and two-dwelling buildings Total DH production in 2007 amounted to 56.3 TWh (47.5 TWh was delivered) and was dominated by biomass, which accounted for 44% of the production

Typical annual loss of thermal energy through distribution is around 10%, as seen in Norway’s district heating network.

Waste heat from nuclear power plants is sometimes used for district heating. The principles for a conventional combination of cogeneration and district heating applies the same for nuclear as it does for a thermal power station. Russia has several cogeneration nuclear plants which together provided 11.4 PJ of district heat in 2005. Russian nuclear district heating was planned to triple by 2015. Other nuclear-powered heating from cogeneration plants are in Ukraine, the Czech Republic, Slovakia, Hungary, Bulgaria, and Switzerland, producing up to about 100 MW per power station.

China’s deep pool system will generate no electricity, but is designed for ultra low cost heat production.

Each of the proposed heating plants would cost about 1.3 billion to 1.4 billion yuan (US$197 million to US$212 million) to build, a fraction of the price of a commercial nuclear power plan. The feasibility studies of DPR in some cities in China show that heating cost using nuclear energy is only one third of that by coal and only one tenth of that by nature gas.

China uses 4 billion tons of coal each year to produce 3900 TWh of electricity. China uses 1000 GW of coal plants. They are talking about getting rid of 12.5% of the coal with these systems. Displacing 125 GW of coal usage for heating would require about 300 of the 400 MW thermal plants. It would cost about $60 billion.

Each steel-and-concrete reactor pool measures about 10 meters in diameter and 20 meters deep, and holds up to 1,800 tonnes of water. A nuclear core is submerged in the water and can create up to 400 megawatts of heat to water to about 90 degrees Celsius for distribution through the city’s public heating network.

A single reactor can produce enough energy to heat 10 million square meters of living space within a 35km (22 mile) range. Two or three reactors would be enough heat a mid-sized city, though bigger metropolitan centers like Beijing would require more units.

The reactor core is placed in the depths of a normal pressure pool, and the water temperature of the core is heated with the static pressure of the water layer to meet heating requirements. Heat is transferred through a two-stage exchange to heating circuit, which can then be transferred to thousands of homes on a heat network.

The reactor is equipped with a high-pressure isolation circuit, which ensures that radiation is isolated from the heat supply network. The pool type low-temperature heating reactor is flexible in site selection, available in both inland and coastal areas and it suits northern China. The service life of a pool-type low-temperature heating reactor is 60 years.

DHR400 Specifications from IAEA

Here is a 258 page IAEA review of SMR (Small Modular Reactors). THe DHR400 is described on pages 19-22.

DHR400 is finalizing the preliminary design (some parameters might change with the optimization of DHR400 design) and seeking for construction license in early 2019. DHR400 has a target commercial operation date of 2021 for the first plant that is expected to be built in Xudapu, Liaoning, China.

Due to the high reliability and inherent safety features, DHR400 can be located in the immediate vicinity of the targeted heating supply area.

The reactor pool is a cylinder with an inside diameter of 10 meters and an overall height of 26 meters, containing the core structure, core shroud, four attenuation barrels, four inertial tanks, the residual heat removal system, the core supporting foundation and the seismic stabilizer brackets inside its 25 m depth of water. The pool is buried underground with an elevation of its bottom of -26 m. The pool is made of reinforced concrete with an inner layer of 5 mm stainless steel and an outer layer of 10 mm carbon steel. The thickness of the surrounding concrete layer is 1.0 m and the bottom plate is 2 m thick. The upper head includes a carbon steel truss and a stainless steel plate, connected to the concrete wall of the pool and provides support for the control rod driven mechanism and the control rod guide tubes. One meter below the upper head there is a gaseous space, which is connected to an engineered venting system to exhaust vapor and other gases. Above the reactor pool there is a 2 m thick movable reinforced concrete plate. The overall structure of the reactor pool provides great resistance to external events including airplanes. The large water inventory in the pool water provides large thermal inertia and a long response time, thus enhances the resistance to system transients and accidents. These features ensure that the core will not meltdown under any accident.

Inherent Safety Features
Instead of augmenting additional engineered safety systems the DHR400 emphasize on inherent safety features. The great heat capacity of the 1800 tons of water inside the reactor pool ensures that the reactor core will be kept submerged in all circumstances, thus no core meltdown could occur. It has negative temperature and void reactivity feedback, therefore the power increase can be effectively restrained. In the event of severe accident, the reactor can automatically shutdown by the inherent negative reactivity feedback, and the reactor core will be kept submerged for as long as 26 days even with no further intervention.

Containment System
There are four barriers precluding a radioactive release to the environment in DHR, including the fuel coating, the reactor pool, the earth around the pool and the reactor building on top of the pool. Due to the low operating temperature and atmospheric pressure on the top of the reactor pool, there are no high-pressure events and instead of a containment, a confinement building is sufficient for protection. The location of the reactor assembly below ground and submerged in 1800 tons of water makes DHR400 highly resistant to
external events including aircraft crashes. Additional protection is provided by the reactor building above the pool.

Primary Heat Exchanger
DHR400 uses 8 plate heat exchangers in its primary coolant system to transfer heat to the secondary loop. Plate heat exchanger is suitable for low temperature difference water to water heat exchange for its small resistance and high efficiency. The leak tightness of the plate heat exchanger is considered to be highly reliable. Even under the circumstances of leakage, the coolant leaks outwards to the pump room. This feature provides great advantages to radioactivity isolation.

Residual Heat Cooling System

The residual heat cooling system of DHR400 is consists of two parts, a 2.4 MW in-pool natural circulation cooling system and a 4 MW out-pool forced circulation cooling system. The temperature of the reactor pool water is kept below boiling point after shutdown and a temperature of 400 C can be achieved with the residual heat cooling system.

Safety Features
The DHR400 is designed with inherent safety features. These include a large volume of water in the reactor pool, two sets of reactor shutdown systems, pool water cooling system and a decay heat removal system. With these designs stable long-term core cooling under all conditions can be achieved.

SOURCES- Sustainability Journal, The Prospective of Nuclear Power in China Yan Xu 1,*, Junjie Kang 2 and Jiahai Yuan (2018), Learning of Power Technologies in China: Staged Dynamic Two-Factor Modeling and Empirical Evidence
Written By Brian Wang, Nextbigfuture.com

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