Case study
Tianwan Nuclear Power Plant Steam Supply

Tianwan nuclear power plant (TNPP) is located in Lianyun district, Lianyungang city, Jiangsu province. The plant is planned to consist of eight PWRs, with a total installed capacity of 9.1 GWe. Total investment is expected to be around CNY 150 billion ($21 billion).

At present, units 1-6 are in operation and units 7&8 are under construction. After these last two units are completed, annual electricity output will exceed 70 TWh, and the plant will have the largest installed operational capacity of any nuclear plant in the world.

In the TNPP steam energy supply project, steam (670 t/h, 270 oC, 6.0 MPa) in the secondary circuit of units 3&4 will be used as the heat source to heat the demineralized water provided by seawater desalinating equipment. The resulting steam at 248 oC and 1.8 MPa will then be provided at a rated flow rate of 600 t/h to users in the petrochemical engineering industry.

For this project, four sets of steam conversion equipment are used. Each set includes one superheater, one evaporator, one primary stage preheater, one secondary stage preheater, as well as a deaerator, primary feedwater pump, and secondary feedwater pump. Each set of steam conversion equipment has a designed capacity that covers 33% of the demand, but the four sets will run in a normal mode of 25% each. The steam conversion equipment can accommodate a wide range of operating conditions and can operate flexibly.

The new design concept of combined active and passive safety for the Hualong One creates challenges for the project integrity, the applicability of the commissioning scheme, and compliance of the commissioning results of the first unit.
Zhang Xianggui
Deputy Plant Manager of Units 3&4,
CNNC Jiangsu Nuclear Power Station
Interview
Zhang Xianggui,
Deputy Plant Manager of Units 3&4, CNNC Jiangsu Nuclear Power Station

What advantages are there to the industrial users of steam from Tianwan, compared to using other sources?

In comparison with conventional fossil energy, nuclear energy is highly reliable, clean and low-carbon. From its design parameters, the TNPP industrial steam energy supply project can provide the petrochemical industry of Lianyungang city with 4.8 million tonnes every year. This could reduce coal use by 0.4 million tonnes per year, equivalent to a reduction in emissions of 1.07 million tonnes of CO2, 184 tonnes SO2 and 263 tonnes of NOx.

What is the potential in China outside of Tianwan?

On 22 September 2020 President Xi Jinping promised in the United Nations 75th Session that our country would try its best to reach peak carbon dioxide emissions by 2030 and to achieve carbon neutrality by 2060. Consistent with this ‘carbon peak & carbon neutrality’ goal, nuclear energy, as a clean and efficient provider of baseload electricity, has been playing an important role in the national energy system. Development of nuclear energy will provide a foundation for the Chinese transition to a clean and low-carbon energy system.

At present, the nuclear heating projects of Shandong Haiyang and Zhejiang Qinshan have demonstrated good operational performance and social benefits. Fuqing and Sanmen are also planning to carry out modifications to supply industrial steam from nuclear energy.

The Tianwan steam supply project, as the first large-scale national project of industrial steam supplied by nuclear energy, will be ready to supply steam at the end of 2023. As well as demonstrate a green, efficient and harmonious use of nuclear energy, it is hoped that industrial steam supply from nuclear energy will become will be widely used in the future.

How are the operations of the industrial site affected by outages at the nuclear plant?

In the design of the Tianwan steam energy supply project, the operations at the industrial site during outages of the nuclear plant were taken into account. Four sets of steam conversion equipment are used for this project, and each one can be supplied with heating steam from both units 3 and 4. During normal operation, units 3 and 4 each provide the steam conversion equipment with 50% heating steam. With one unit offline, the other unit would provide 100% heating steam to the steam conversion equipment, guaranteeing a reliable steam supply to the users.

Supply is also maintained in the event that one set of steam conversion equipment needs to be repaired, as the other three sets can each transition to 33% of demand.

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