Design evolution: Chinese reactors20 August 2014
Growth of nuclear power in China has been characterised by the evolution of several domestic and imported reactor designs. Caroline Peachey provides an in-depth review of the development of China’s nuclear power reactors.
There are 20 reactors in operation in China: two pressurised heavy-water reactors and 18 pressurised water reactors (PWRs), with a further 28 units under construction. The mainstay of the Chinese reactor programme has been and remains the PWR. There are different Chinese-developed PWR models under construction, with more advanced versions in the design stage.
"The current mix of nuclear technology in China is not based on any particular decision," said Huang Wei, minister counsellor and alternate to the resident representative at the Chinese Permanent Mission to the International Atomic Energy Agency (IAEA) in a recent interview.
"Due to historic reasons, such as financing and bilateral cooperation, different nuclear technologies from France, Russia, Canada and the US were introduced in the past."
In addition to its PWR construction programme, China is building the HTR-PM, a demonstration high-temperature, gas-cooled reactor. While the first HTR-PM project only began construction in late 2012, the design should be considered a serious contender given that it has big investment by China Huaneng Group, one of the largest listed power producers in China, and it wants to develop nuclear power. It is also significant that Shidaowan in Shandong province, the site of the first HTR-PM, is set to become a major nuclear centre, showcasing the latest Chinese reactor technology. This will include the first Chinese evolution of the Westinghouse AP1000 - the CAP1400 - which is scheduled for first concrete this year.
The development of Chinese reactor design has a consistent strategy; China has imported a reactor design, learned from it, and then used its own, and international, experience and feedback to improve its domestic reactor technology.
"Cross-fertilisation of reactor technology concepts between the imported designs and local designs is still happening today," say Jonathan Hinze and Yun Zhou of Ux Consulting.
The big three nuclear developers in China
There are three authorised nuclear power plant developers in China:
- China General Nuclear Corporation (CGN)
- China National Nuclear Corporation (CNNC)
- China Power Investment Corporation (CPIC).
These developers are licensed to invest as controlling shareholders and operate nuclear power plants in China. Any other public or private companies are to have minority shares in new Chinese nuclear projects.
Could China Huaneng Group join these three? In 2012, it began work on the HTR-PM demonstration project in partnership with China Nuclear Engineering Group and the Institute of Nuclear & New Energy Technology at Tsinghua University. However, this is considered a research programme, and despite holding a majority stake in the project, Huaneng is still not licensed to invest in and operate nuclear power plants. China Huaneng Group split off from the State Power Corporation in 2002, along with China Datang Corporation, Huadian Power International and China Guodian Corporation. Like Huaneng, each of these companies has minority
shares in projects under construction and development.
In addition to these developers, China's State Nuclear Power Technology Corporation (SNPTC) was founded in 2007 as the national body responsible for the transfer of generation III nuclear power technology into China. SNPTC is responsible for engineering design and project management, and the formation of a Chinese brand of nuclear power technology via "digestion, absorption and re-innovation of the imported advanced technology", (currently the Westinghouse AP1000).
China General Nuclear Corporation
CGN is responsible for over half of China's nuclear programme. It was founded in 1994 as China Guangdong Nuclear Power Holding Corporation (CGNPC), but changed its name to China General Nuclear Corporation in April 2013 as a reflection that its operations extend beyond Guangdong province. However, as would be expected, CGN retains priority within that region.
The company has 11 reactors in operation (10.5GW) and 13 under construction (16.6GW). It is not solely a nuclear company; CGN's core business is defined as the development of clean energy projects, which include solar, wind and hydro, as well as nuclear.
All of CGN's reactors are based on French technology. Most have evolved from the first 900MWe units that were exported by Framatome in the '80s for Daya Bay. The CPR-1000 design is described as a "significantly upgraded version" of those first M310 units, which were based on Graveline's 5 and 6 in France. There are 15 CPR-1000 units under construction at six different sites in China. The reactor types include:
- CPR1000: a 1,086MWe capacity, three-loop PWR it has a design life that could extend beyond 40 years as a result of efforts to reduce impurities (such as copper, sulphur and phosphorous) in the reactor pressure vessel (RPV) material. Other changes to the original M310 design include eliminating a welded joint in the RPV, which shortens production time and eliminates the need to inspect the weld during operation.
- ACPR1000: the design has ten major technical improvements over its predecessor the CPR-1000, according to CGN, among them greater capacity, simplified reactor chemical and volume control system, optimised distributed control system, enhanced mitigation capacity of nuclear steam supply system, longer design life and improved resistance to external events. In parallel with its own line of reactors, CGN is the majority partner (51%) in a project to build two 1,750MW AREVA EPR reactors at the Taishan site in Guangdong province, with EDF (30%) and Yudean Group (19%).
State-owned CNNC, whose primary territory is mainly on the east coast near Shanghai and Zhejiang province, has led the development of a line of reactor technology named CNP. In the past, CNNC has also imported reactors from Canada (CANDU 6) at Qinshan III. It also operates two VVER-1000 reactors at Tianwan, and is developing two more at the same site.
The company's reactor development started in the '70s when the Shanghai Nuclear Engineering Research and Design Institute (SNERDI), part of CNNC, began work to develop a small indigenous reactor based on a submarine reactor. The result was the 300MW, single-loop CNP-300 PWR, which was first built at Qinshan 1 (start-up in 1991). The most recent CNNC reactor design to enter operation is the CNP-600, a 650MW, two-loop PWR: The details of the reactors include:
- CNP-600 and ACP-600: classified as a generation II reactor design, the first CNP-600 reactor began operation at Qinshan II-1 in 2002, and the most recent startup was Qinshan II-4 in December 2011. Changjiang 1 and 2 are the only two CNP-600s under construction. However, CNNC is developing an advanced version, named the ACP-600.
- ACP-1000: CNNC began work on this in the '90s with the help of vendors Westinghouse and Framatome (now AREVA). The first CNP-1000 units were due to be built at Fangjiashan; however, the design was changed to a CPR-1000. CNNC's focus switched to the development of a more advanced generation-III version of the CNP-1000, the ACP-1000. In 2013, China announced that it had independently developed this three-loop PWR with Chinese authorities claiming full intellectual property (IP) rights over the design. China's current aim is to only build generation III and generation IV projects after 2015.
CNNC had planned two ACP-1000 units for Fuqing 5 and 6 in Fujian province. However, it is now thought that the newer ACC1000 design (see below) will be built there instead.
That means CNNC's first ACP-1000 could be exported, as it is planned for Pakistan's Karachi Coastal nuclear power project.
Joint offering: ACC1000
CGN and CNNC are working together in a 50-50 partnership on a third-generation nuclear power plant, which they claim will have independent IP rights. This 1,150MW design will combine the ACPR-1000 (CGN) and ACP-1000 (CNNC) designs. It is also referred to as ACC1000 or Hualong-1000. According to CGN, a demonstration project is planned for Fangchenggang phase II. In addition, it might be chosen for Fuqing 5 and 6.
SNPTC: AP1000 to CAP1000
SNPTC is the national body responsible for the transfer of generation III nuclear power technology into China. SNPTC is majority owned (60%) by the State Council. CNNC, CPI, CGNPC and China National Technical Import & Export Corporation each hold a 10% stake. Since its inception in 2007, SNPTC has included the SNERDI, formerly part of CNNC, as an R&D arm.
The Westinghouse AP1000 is the basis of China's move to generation III technology, with four reactors under construction at Sanmen and Haiyang for CNNC and CPI, respectively. SNPTC is responsible for the engineering, design and project management of these first AP1000 projects, which are being built as part of a technology transfer agreement with Westinghouse. The Chinese supply chain takes an increasingly large share of reactor construction. The next eight units (CAP-1000s) will involve higher local content (the aim is for 80%), although they will contain some critical components from Westinghouse, including digital control systems, fuel and reactor internals. The AP1000 design has also undergone post-Fukushima enhancements, including the addition of waterproof doors, 72-hour water supply, enhanced spent-fuel pool level-monitoring instruments, an improved emergency command centre and incorporation of full-scope severe accident management guidelines.
SNPTC is also leading the development of the Chinese evolution of the AP1000, dubbed the CAP1400. Agreements with Westinghouse stipulate that SNPTC will own the IP rights for any derivatives over 1,350MWe, according to the World Nuclear Association.
Conceptual design of the CAP1400, a 1,530MWe two-loop advanced PWR was completed in 2010, with the basic design completed in 2011. In January 2014, SNPTC announced that the technology had passed a design review by the China National Energy Administration, and that the key parameters of CAP1400 had been "fixed and approved" by the state.
The construction design was 60% complete as of January 2014.
Site-preparation works for the first CAP1400 demonstration project began in March 2013, and the first nuclear concrete is expected this year at the Shidaowan site in Rongcheng, Shandong province.
China's quest for a high-temperature reactor (HTR) began in the '70s. Construction of a 10MW gas-cooled HTR (HTR-10) was approved in 1992, and started in 1995. The project achieved first criticality in 2000 and began operation in 2003. In December 2012, first concrete was poured for the 200MW HTR-PM demonstration power plant, based on the HTR-10. The HTR-PM project is managed by Huaneng Shidaowan Nuclear Power Company (HSNPC), which comprises China Huaneng Group (via subsidiary Huaneng Nuclear Power Development Company, 47.5%), China Nuclear Engineering Group (32.5%), and Tsinghua University (20.0%).
As of the end of 2013, civil work for the underground part of nuclear island buildings had been completed. The main components - including reactor pressure vessels, core internals and steam generators - are being fabricated by domestic manufacturers. A fuel factory that will supply 300,000 fuel elements each year to the HTR-PM is also being built in northern China. According to the project schedule, HTR-PM is expected to be commissioned in 2017.
Future technology outlook
Following the Fukushima accident and the release of the Chinese nuclear safety plan, China will build "a few" Gen II+ projects between now and 2015, says Yun Zhou of Ux Consulting. These are projects that were either already under construction or are paired with existing units. After 2015, China aims to only build Gen III and Gen IV projects.
"Currently, officially, the National Energy Bureau only supports AP1000 as the only Gen III model to mass produce and CAP1400 as the only Gen III model to export," she said. "However, the government will not oppose other models to develop and export, if any. China is developing its own Gen III ACC1000, which could serve as a supplement for domestic and exporting uses." (The CAP1400 has been chosen for export because the Chinese claim it has 100% Chinese IP).
Steve Kidd, senior partner at East Cliff Consulting, agrees. "AP1000s are expected to constitute the main part of the Chinese domestic programme (for now at least)," he said. "The other mainstay of the Chinese programme will be the ACC1000, which is the outcome of the battle between CNNC and CGN for the Chinese Gen III-qualified 1,000MW unit."
As the ACC1000 design is derived in part from the French M310s at Daya Bay and Ling Ao Phase I, it is believed that it cannot be exported due to French IP concerns. But Kidd says the ACC1000 is expected to remain important within China, and can be built far more cheaply than the AP1000 until the latter's localisation rate is much higher.
With respect to Chinese HTR technology, the goal is eventually to export the HTR-PM design with independent IP rights. However, since existing Gen III reactor lifetimes could be as long as 60 years, the HTR will be at most a supplement to the domestic market in the next several decades.
China is investing in small modular reactor (SMR) R&D programmes in order to be prepared for a potential international market. However, the nature of China's electricity demands and geography mean that SMRs will not play a significant role in China in the near future.