Safety and effective developing nuclear power to realize green and low-carbon development

Abstract

This paper analyzes the role of nuclear power of Chinas energy structure and industry system. Comparing with other renewable energy the nuclear power chain has very low greenhouse gas emission, so it will play more important role in Chinas low-carbon economy. The paper also discussed the necessity of nuclear power development to achieve emission reduction, energy structure adjustment, nuclear power safety, environmental protection, enhancement of nuclear power technology, nuclear waste treatment, and disposal, as well as nuclear power plant decommissioning. Based on the safety record and situation of the existing power plants in China, the current status of the development of world nuclear power technology, and the features of the independently designed advanced power plants in China, this paper aims to demonstrate the safety of nuclear power. A nuclear power plant will not cause harm either to the environment and nor to the public according to the real data of radioactivity release, which are obtained from an operational nuclear plant. The development of nuclear power technology can enhance the safety of nuclear power. Further, this paper discusses issues related to the nuclear fuel cycle, the treatment, and disposal strategies of nuclear waste, and the decommissioning of a nuclear power plant, all of which are issues of public concern.

Keywords

Nuclear power and nuclear energy ; Role of nuclear power ; Scale development ; Nuclear safety ; Radioactivity release ; Nuclear fuel cycle

1. Introduction

To implement the Four-Energy Revolution of General Secretary Xi Jinping and to realize the promise of emission reduction by 2020 and 2030, which China has made to the international community, its energy structure and power structure must undergo profound adjustment and transformation. The development of nuclear power and the construction of infrastructures is an important link of energy production revolution. However, after the Fukushima nuclear accident, some doubts on nuclear power safety and fears of nuclear accidents and radioactive leaks have been raised in the international community, in general, and in China, in particular. To promote nuclear power development and also rebuild confidence on nuclear power safety, this paper focuses on the status and role of nuclear power in the energy structure, nuclear safety, radioactive waste management and control, nuclear waste treatment and disposal, as well as nuclear power plant decommissioning.

2. Benefits of nuclear power development in reducing the CO₂ emission, improving the environment, and realizing green, low-carbon energy development

Within 30 years of development, China has established a complete nuclear industry system through comprehensive nuclear scientific research. As a result, Chinas nuclear power industry has already begun to take shape: 27 units are currently operational with a total capacity of 25.5 GW. At present, 24 units with a total capacity of 26 GW are under construction, comprising 36% of the total world construction capacity and ranking first in the world.

2.1. The current situation of energy and environment in China

Chinas economic and social development is facing the dual challenge of how to balance its limited domestic and environmental resources while mitigating CO₂ emission to address climate change. At present, Chinas ecological environment pollution is extremely serious. In recent years, PM2.5 has become a serious threat to peoples health and the main killer of the lucky index. For this reason, managing haze and reducing emissions have become the urgent strategic tasks of Chinas energy structure adjustment.

China is a big consumer of carbon energy, coal, and other traditional fossil fuel-based energy sources. With the huge amounts of CO₂ emissions, China has faced great pressure from the international community to reduce carbon emissions. In 2009, the Chinese government made a commitment to reduce carbon emissions per unit GDP by 40%–45% by the year 2020. In order to achieve this goal, Chinas energy structure must transform to a low-carbon emission model, such that by 2020, 15% of the total primary energy consumption must come from non-fossil energy sources. In the 2015 Paris Climate Change Conference, the Chinese government also promised to reach CO₂ emission peak by 2030, in which the proportion of non-fossil energy in the total primary energy consumption must already reach 20% of the total electricity consumption (NPB, 2016 ).

2.2. Expectations regarding Chinas energy development

Chinas economy is gradually moving towards a stable growth period; in fact, towards the middle of the 21st century, the per capita GNP will reach the level of moderately developed countries (CEPPEI, 2015 ). Owing to the industrial structure adjustment and enhancement, the consumption of energy for secondary industries in China will continue to decline along with the elastic coefficient of electricity (Table 1 ). During the 13th and 14th Five-Year Plans, the elastic coefficient of electricity will be reduced to 0.6–0.9. During the period of 2025–2050, this will be further reduced to below 0.5. By the years 2020, 2025, and 2030, it is expected that the national total social power demand will be 7.5, 9, and 10 PW h, representing average annual growth rates of 5.9%, 3.7%, and 2.2%, respectively. Taking into account the emission reduction commitments, China should strengthen the development and use of non-fossil energy (CNEA, 2013  ;  CNEA, 2015 ). Table 1 below lists the expected primary energy consumption structure and scale during the 13th Five-Year Plan and subsequent periods.

Table 1. Expected primary energy consumption structure and scale.

Items		2014 (real)	2020	2030
Total amount of consumption (Gtce)		4.26	5	6
Non-fossil energy		0.47	0.75	1.2
Fossil energy		3.79	4.25	4.80
Coal		2.81	3.20	3.07
Oil		0.73	0.55	0.83
Natural gas		0.25	0.50	0.90
Consumption ratio (%)	Non-fossil energy	11.1	15.0	20.0
	Fossil energy	88.9	85.0	80.0
	Coal	66.0	64.0	51.2
	Oil	17.1	11.0	13.8
	Natural gas	5.8	10.0	15.0

By 2020 and 2030, the scales of non-fossil energy by non-power utilization are expected to be 0.1 and 0.13 tce, respectively, whereas the scales by power generation are expected to be 0.65 and 1.07 tce, respectively. In addition, by 2020 and 2030, the unit coal consumptions will be 290 and 280 gce (kW h)⁻¹ , respectively. This means that in 2020 and 2030 non-fossil energy-generating capacities shall reach 2241.4 and 3821.4 TW h, respectively (Kang, 2014 ).

2.3. Development of non-fossil power generation excluding nuclear power

2.3.1. Conventional hydropower

China is rich in hydropower resources. With current technologies and facilities, it can generate about 660 GW; however, with the subsequent hydropower developments, plants will gradually move to the west, where development conditions are relatively difficult, plant construction costs continue to rise, and issues such as immigration, environmental protection, and others, continue to become prominent. During the 13th Five-Year Plan new hydropower plants have been constructed in the Dadu River and Lancang River Basin, generating a total of 26.76 GW; in 2020–2030, development will mainly concentrate in the Jinsha River, Nujiang River, and the Yalong River Basin, which is expected to generate a total of 83.67 GW. By 2020, Chinas hydropower installed capacity is expected to reach 350 GW, generating about 1295 TW h; by 2030, this is expected to reach a maximum of 450 GW, generating about 1665 TW h by 2030.

2.3.2. Wind power

Chinas wind power resources are very rich; onshore wind resource of about 70 m higher is about 2.57 TW, while offshore resource with depths of 5–25 m is about 0.19 TW, thus comprising a total of about 2.76 TW. Although wind power development is conducive to reducing greenhouse gas (GHG) emissions, it may also have negative impacts on the ecology and the environment. This may also have climatic and seasonal impacts and can lead to a low load factor. Wind power development must consider the combination of centralized and decentralized modes; it must take into account the characteristics of the power grid and power load, so that the problem of long distance transmission can be resolved. By 2020, wind power installed capacity and power generation capacity are expected to reach 0.2 TW and 400 TW h, respectively, while in 2030, wind power installed capacity and power generation capacity are expected to reach 0.4 TW and 800 TW h, respectively.

2.3.3. Solar energy

Solar energy is a form of clean energy with no pollutant emissions. However, it also has the following disadvantages: it produces a certain amount of light pollution, it entails higher production costs, its utilization factor is low, and it has several constraints in terms of development scale and speed. During the 13th Five-Year Plan period, orderly photovoltaic base construction will be promoted, and sites shall be mainly located in the northwestern regions of Xinjiang, Qinghai, and so on. By 2020, solar power installed capacity is expected to reach 0.10–0.14 TW, with a generating capacity of up to 120–168 TW h. By 2030, installed capacity is expected to reach about 0.4 TW, with a generating capacity of about 480 TW h.

2.4. Nuclear power as an energy source with the largest emission reduction effect

A nuclear power plant does not emit SO₂ , particle matters, and other air pollutants; even with plant effluents, radioactive material radiation exposure in the surrounding residents is generally much lower than the natural background level. In 2011, the Chinese Academy of Engineering carried out a study on the GHG emission chains for different power generation (CAE, 2015 ). The study presented several conclusions. First, for the nuclear power chain, the CO₂ emission is 6.2 g (kW h)⁻¹ (CO₂ emissions per kW h), including uranium mining, uranium conversion, uranium enrichment, and nuclear power plant construction and operation. Considering the total nuclear fuel cycle (including spent fuel reprocessing and waste disposal), the total GHG emissions from the nuclear fuel cycle is 11.9 g (kW h)⁻¹ CO₂ . Second, it is found that the coal power chain includes coal production, coal transport links, coal power plant construction, operation and retirement, and power transmission and distribution, to name a few. For these stages, the CO₂ emissions reach 1072.4 g (kW h)⁻¹ . Third, CO₂ emissions for the hydropower chain, the wind power chain, and solar energy chain are 0.81–12.8 g (kW h)⁻¹ , 15.9–18.6 g (kW h)⁻¹ , and 56.3–89.9 g (kW h)⁻¹ , respectively. From the total GHG emissions, the nuclear power chain contributes only about 1% of the coal chain. In terms of the marginal cost of global carbon emissions, the marginal cost of nuclear energy is much lower than those of wind, solar, carbon capture, and storage technology. Around 2030, the nuclear power will reach about 150 GWe of the installed capacity, this means that 400 Mtce will be reduced, that is, the about 1/6 of coal supply will be replaced, and overall CO₂ emissions shall be reduced by nearly 1500 Mt.

The annual load factor of nuclear power in China is about 90%, which is much higher than those of coal-fired power, wind power, and solar power. Considering that nuclear power is a source of stable, clean, and high-density energy, nuclear power development is expected to make a breakthrough in Chinas energy resources and environmental constraints. Moreover, nuclear power has an irreplaceable role in ensuring energy security, reducing CO₂ emissions, and achieving green, low-carbon development; hence, nuclear power will become an important pillar of Chinas future sustainable energy system. To this end, Chinas objectives in the long-term development of nuclear power planning are as follows: to achieve 58 GWe in operation and 30 GWe of nuclear power capacity in construction by 2020, as well as to achieve 150 GWe of nuclear power capacity in operation, and 50 GWe of nuclear power capacity in construction by 2030. This means that there will be 6–8 units to be built per year. In comparison, throughout the history of nuclear power development, the U.S. constructed 6–8 units of nuclear power plants annually in the peak of its nuclear power development (IAEA, 2015 ).

According to the findings of the present nuclear power plant site exploration and screening, the preliminary nuclear power site development has generated about 360 GW, the coastal site resources are 200 GW, and the inland site resources are 160 GW, all of which are enough to meet the needs of the development of nuclear power by the target years of 2020 and 2030.

2.5. Two scenarios to ensure 20% non-fossil energy power structure by 2030

Here, we proposed two scenarios (Table 2 ) to ensure 20% non-fossil energy power structure by 2030: 1) 450 GW of hydropower, nuclear power of 160 GW (slightly higher than the planning assumptions), wind power of 310 GW, and solar power of 310 GW; and 2) 430 GW of hydropower, nuclear power of 130 GW (slightly below the planning assumptions), wind power of 400 GW, and solar power of 400 GW. Table 2 below lists the expected non-fossil energy power generation capacities.

Table 2. Two scenarios to ensure 20% non-fossil energy power structure by 2030.

Items	Scenario 1	Scenario 2
Generate electricity capacity of non-fossil energy (GW)	1230	1360
Hydropower	450	430
Nuclear power	160	130
Solar energy power	310	400
Wind power	310	400
Power generation quantity of non-fossil energy (TW h)	3825	3820
Hydropower	1665	1591
Nuclear power	1168	949
Solar energy power	372	480
Wind power	620	800
Convert to standard coal for total power generation (Mtce)	1071	1070
Convert to standard coal for other forms of non-fossil energy (Mtce)	130	130
Ratio of non-fossil energy (%)	20	20

If the wind power and solar power generation scales are greater, then peak capacity demand shall also be higher, with control wind abandoned ratio of less than 10%. Scenario 1: the installed pumped storage plant and gas turbine plant will be respectively required to generate 95 and 210 GW; Scenario 2: the pumped storage plant and gas turbine plant will be respectively required to reach generation capacities of 110 and 210 GW. Given that wind power and solar power investments are higher than that required for nuclear power development, along with the greater pumped storage and gas turbine plant investments, the total investments shall be much higher. Thus, the second scenario is less economical, suggesting that focusing on the developing nuclear power and hydropower is more conducive to the development of the national economy.

3. Guaranteeing the safety of nuclear power

3.1. Good safety record of Chinas nuclear power systems

Chinas nuclear power development has the late-developing advantage that is, its safety standards and regulations follow the current international standards and regulations, which represent the highest safety standards of nuclear power (Ye and Zhang, 2010 ). Meanwhile, with continuous improvement and enhancements in terms of design, the latest, most advanced technology is fully used. Since Chinas first nuclear power plant (Qinshan Phase I) began operating 20 years ago, all the nuclear power plants that have been established in the country are in good operating conditions. According to the International Nuclear Accident Classification (INIS, published by IAEA and NEA in 1991, used in 2001), no safety events (accidents) classified as level 2 or higher than 2 have occurred. In addition, the main operating indicators are higher than the world average levels, some indicators are at the international forefront, nuclear power plant personnel exposure is lower than the national standard, and environmental radiation levels around the nuclear power plants are maintained within the natural background range, with no known adverse effects on public health. Furthermore, after the Fukushima nuclear accident, the Chinese government implemented a series of safety measures and standards based on international research and experience to prevent a similar event such as that in Fukushima (Ye, 2011 ).

3.2. China as one of the first countries to introduce and develop third-generation nuclear power technology

After the Chernobyl nuclear power plant accident, the main nuclear power countries have actively worked to develop safer and more economic nuclear power design standard specifications from the late 1980s to the early 1990s. Their efforts resulted in the Utility Requirements Document (URD, implemented in the U.S.) and the European Utility Requirements (EUR, implemented in western Europe), both of which are based on the developed and designed advanced light water reactor nuclear power plant, also known as the third generation light water reactor nuclear power plant.

China took the lead to introduce four sets of AP000 advanced pressure reactor NPP constructed in Sanmen and Haiyang, which was the first generation of its kind. At the same time, China introduced the construction of two sets of EPR1700 located in Taishan. The most significant technical characteristics of third-generation PWR-NPP are its complete severe accident prevention and mitigation facilities. With the increase in the probability safety goals in one order of magnitude, this means that the requirements of core damage probability (CDF) are less than one hundred thousandth, and large quantities of radioactive release probability (LRF) are less than one millionth.

For AP1000, its main features are as follows: 1) compact arrangement of the reactor coolant system, with two loops, each composed of a steam generator and two canned electric motor pumps that are directly installed under the steam generator outlet head; 2) passive safety systems, such as the passive emergency core cooling system, passive containment cooling system, and so on; 3) a complete set of severe accident mitigation facilities, including additional pressure exhaust relief system, automatic hydrogen composite device, and reactor cavity flooding system to derive resident heat and ensure core melt retention in the pressure vessel; 4) seismic design basis of 0.3 g in order to adapt to more different conditions on-site; 5) modular design and construction, which are beneficial to reducing the construction period; and 6) the inclusion of a digital instrument and control system.

EPR1700 has the following main features: 1) four-loop reactor coolant system, the core consists of 241 fuel assembly, which can use 50% MOX fuel; 2) a double containment system to protect the reactor building against the impact of large commercial aircrafts; 3) increased degree of redundancy of the safety system from 2 to 4 channels; 4) a set of severe accident mitigation facilities, including additional pressure relief discharge system, hydrogen recombination, and core catcher to collect melt core; and 5) digital instrument and control system.

Apart from the above, China independently developed an advanced pressurized water reactor nuclear power plant called Hualong No.1. Based on the mature technology and experience of large-scale nuclear power plant construction and operation in China, and with constant optimization and improvement, Hualong No.1 now meets the standards of advanced PWR nuclear power plants. Construction has already begun in Fuqing in Fujian province, Fangchenggang in Guangxi province, and Karachi, Pakistan. The main features of this system are as follows: 1) a standard three-loop design with the reactor core using 177 fuel assembles; 2) reduced core power density to meet the thermal safety margin of more than 15%; 3) uses both an active and passive safety system, wherein the active system can quickly eliminate accidents, while the passive system can ensure the safety of nuclear power plants in case of loss of function of active safety systems and station blackout (SBO); 4) a double containment, which can protect against the impact of large commercial aircrafts; 5) a set of severe accident mitigation facilities, including the creation of pressurizer relief discharge system, passive hydrogen recombination device, and the reactor cavity flooding system, to derive heat and maintain the melt core retention in the reactor pressurized vessel; 6) seismic design basis of 0.3 g, which can adapt to different on-site conditions; and 7) a full digital instrument and control system.

Based on technology introduction, digestion, and absorption, China has also independently developed and designed the CAP1400, which has the following main features: 1) increased number of reactor core fuel assembly to meet the requirements of thermal safety margin that is greater than 15%; 2) increased output of nuclear power plant to 1400 MWe; 3) increased size and volume of steel containment, with an outer shield containment that can protect the reactor building against the impact of large commercial aircrafts; 4) a main circulating pump with 50 frequency power supply that is consistent with Chinas power standard, which can improve the reliability of the main pump power supply; 5) a redesigned passive safety system, such as passive emergency core cooling system and a passive containment cooling system; 6) severe accident mitigation facilities, including additional pressure relief automatic discharge system, hydrogen combined device, and the reactor cavity flooding system, to derive heat and keep the core melt retention in the reactor pressurized vessel; 7) modular design and construction, which can shorten the construction period; 8) a digital instrument and control system; and 9) seismic design basis of 0.3 g, to help the system adapt to different on-site conditions.

The development of these third-generation nuclear power technologies can help achieve the goal of practically eliminating large-scale emission of radioactive material.

4. Nuclear power as a form of clean energy

As previously mentioned, nuclear power does not emit GHGs, harmful gases, and dust, because radioactive effluents are under strict processing and monitoring. According to the state environmental protection laws, based on the emission limits approved by the administrative department, emissions of radioactive effluents from nuclear power plants in China have been strictly controlled, and the environments surrounding its nuclear power plants are being effectively monitored. As shown in Table 3 , for the 2013 monitoring, in Dayabay Nuclear Power Plant, inert gas cumulative emissions are 9.65 × 10¹¹  Bq, accounting for 0.138% of the state standards; for Qinshan Second Nuclear Power Plant, inert gas cumulative emissions are 9.13 × 10¹¹  Bq, accounting for 0.315% of the state standards. The radioactive effluent monitoring results of the nuclear power plants show that the radioactive effluents of Chinas commercially operated nuclear power plants are far below the national standard index (Lu, 2012  ;  QNPP, 2014 ).

Table 3. The radioactive effluent monitoring results of the nuclear power plants in 2013.

Radioactive effluents		Dayabay NPP		Qingshan second NPP
		(Bq)	(%)	(Bq)	(%)
Gaseous effluents	Inert gas	9.65 × 1011	0.138	9.13 × 1011	0.315
	Halogen	6.93 × 106	0.028	6.48 × 106	0.360
	Aerosol	4.87 × 106	0.128	1.29 × 107	0.299
Liquid effluents	Tritium	3.85 × 1013	17.111	6.35 × 1013	57.72
	Remaining nuclide	1.81 × 108	0.139	1.23 × 109	2.181

In accordance with the provisions, the occupational exposure for nuclear power plant workers must comply with the following requirement: the average annual effective dose for 5 years must not be more than 20 mSv, and that for 1 year must not be more than 50 mSv. According to 2013 monitoring data, at the Dayabay Nuclear Power Plant, the average personal dose is 0.549 mSv, while the maximum individual dose is 13.345 mSv. For the Qinshan Second Nuclear Power Plant, the average individual dose is 0.385 mSv, and annual maximum individual dose is 8.726 mSv. All of these values are far lower than the state standard (MEP and AQSIQ, 2011  ;  Ye and Zhang, 2010 ).

Low and intermediate levels of radioactive solid waste are also subject to strict control. According to the provisions, each nuclear power plant must have no more than 50 m³ of solid waste. Then, after temporary storage, these low and intermediate levels of radioactive solid wastes in the nuclear power plant must be transported to the permanent disposal site. The solid wastes are currently stored in the nuclear power plant, subject to complete monitoring and controlling. By national standards, permanent disposal sites are currently being established and built in the related areas.

5. Necessity of inland nuclear power construction

Chinas eastern coastal areas have relatively developed economies, which are characterized by greater electricity demand, limited energy resources, and larger regional power grid capacities. Therefore, these areas are in need of nuclear power units with larger capacities. Hence, Chinas nuclear power units were first constructed in these eastern coastal areas. Along with inland economic development, which gradually moves from eastern to central and western areas, the central and western regions also need nuclear power, especially areas that suffer from limited energy. This process is a historical necessity.

The above conditions necessitate the construction of inland nuclear power plants. Rapid economic growth is related to the development of the power grid capacities in some inland provinces. In addition, some provinces that lack coal and hydropower energy resources cannot generate power during severe weather conditions. For example, the severe snowfall in 2008 resulted in long power outages in southern provinces, which of course, led to a host of serious consequences. Relying only on long-distance transmission and long-distance coal transportation cannot guarantee the security of an electricity grid. Based on the abovementioned reasons, constructing nuclear power plants as a backup power supply that does not depend on fuel transportation is highly essential.

Inland nuclear power plants mostly use a cooling tower closed cycle to remove resident heat; this does not result in heat pollution in surrounding river water, and no circulation cooling water is needed. In fact, only 1%–3% make-up water is needed to compensate for the evaporated water; therefore, the nuclear power plant will not compete with the local water demand for water resources. Given that no cooling water is needed to dilute radioactive waste, Revision draft of the state standards (GB 14587), has proposed a concentration of 100 Bq L⁻¹ of radioactive waste as a control value to reduce the river dilution requirements. In fact, industrial wastewater treatment technology can purify radioactive waste water to about 20–30 Bq L⁻¹ ; moreover, the treated water can be reused in the process, so that the goal of “zero discharge” or near “zero discharge” can be realized. If necessary, electronic osmosis can also be used to continue the purification to about 2 Bq L⁻¹ , which is equivalent to natural levels. If a nuclear power plant waste water discharge system uses a tank type method, this means that the discharge is to be controlled according to the radioactive nuclide contents in the wastewater. In this case, special treatment can be used to achieve further purification. In conclusion, the liquid waste discharge of nuclear power plants will not cause adverse effects on the environment.

The emission of radioactive waste gas can also be controlled. According to statistical data of meteorological conditions in 26 selected inland sites in China, there are 15 sites where annual average wind speed is less than 2 m s⁻¹ and there are 14 sites where the calm wind frequency is greater than 10%, among them, there are 3 sites where the zero wind frequency is higher than 30%. A higher calm wind frequency is an important feature of selected inland sites in China. Meanwhile, the long-term atmospheric dispersion factors of the 26 selected inland sites are calculated, and the results are as follows: in all boundaries of non-residential areas, the average annual atmospheric dispersion factor in the range of 8.8 × 10⁻⁸ –7.6 × 10⁻⁶  s m⁻³ are lower than the long-term atmospheric dispersion factor of 2 × 10⁻⁵  s m⁻³ given in the design documents of AP1000. Meanwhile, according to the planning capacity and under an operational condition, upon the release of radioactive materials around the site, the calculated personal maximum effective dose and dose through gaseous way is less than 40% of the constraint value of 0.25 mSv; moreover, the majority is less than 20%, thus meeting the requirements of national standards. A tracer experiment and a detailed study of the on-site atmospheric dispersion situations were conducted in 2 typical inland sites from the abovementioned 26 sites. Using the atmospheric diffusion model in accordance with the actual situation of the sites, the site annual average dispersion factor is calculated. Further analysis shows that the public personal maximum effective dose caused by airborne radioactive effluents around these sites reach not more than 10⁻⁷ –10⁻⁶  Sv per year, which does not exceed 1% of the dose constraint value (0.25 mSv) under operating conditions.

6. Continuous research to improve the safety of nuclear power systems

The entire international research community, along with researchers in China, have conducted research on nuclear power plant safety, which includes the following topics: eliminating large-scale radioactive leaks, maintaining the integrity of the containment units, severe accident prevention and mitigation (including severe accident management guidelines, extreme natural disaster prevention, and management guidelines), the accident tolerance fuel (ATF) research, and so on. Specifically, research on ATF has focused on reducing the risk of the core (fuel) melting, reducing or eliminating the hydrogen explosion caused by the zirconium water reaction, and improving the capacity of the fuel to contain the fission product. In 2011, the U.S. Congress passed an act requiring the Department of Energy to develop a plan to enhance the accident resistance capability of nuclear fuel for all its nuclear power plants under operation. The goal of this act is to create the first ATF fuel assemblies into commercial reactors to be tested in 2022. Similarly, France, Japan, South Korea, and other countries also conducted the development of ATF; the OECD organized a number of international conferences on ATF; and the IAEA is preparing an ATFOR cooperative research project. Related research institutes in China are also developing ATF, and at present, we have been studying the carbon fiber industry as well as related technologies to facilitate the use of SiC for coated fuels. The success of ATF research domestic and abroad can improve the safety of both new and currently operational nuclear power plants.

7. Nuclear waste and nuclear power plant decommissioning

7.1. High-level radioactive nuclear waste

Each nuclear power plant discharges about 20–30 tons of spent fuel per year; these are stored in a spent fuel pool, which can store discharges for up to 15–20 years along with a whole fuel set of a single reactor. In PWR, spent fuel contains approximately 95% U-238, 0.9% U-235, 1% Pu-239, 3% fission products, and 0.1% inferior Actinium. Of these, only the fission products and the inferior Actinium are high-level, long-lived radioactive wastes, while others are strategic materials that can be reused. In China, the technical route of the closed fuel cycle is determined to extract uranium and plutonium from spent-fuel to fuel for the fast breeder reactor. In China, the first independently designed power reactor spent-fuel reprocessing pilot plant has been successfully established. Following this development, the first commercial scale spent-fuel reprocessing demonstration plant is currently being built in order to achieve a nuclear fuel closed cycle.

China has also built an experimental fast reactor that is now under operation. To date, it has continued to design and construct large-capacity demonstration fast reactors, marking the beginning of the fourth-generation nuclear power technology. This lays the foundation for the development of future nuclear power technologies, which can facilitate the fuller utilization of nuclear resources.

The long-lived inferior Actinium in spent fuel can be driven by the fast reactor or accelerator driven sub-critical system (ADS); the transmutation will turn waste into treasure. ADS has a higher effect than the fast reactor (compared with the fast reactor as 12/5), because its neutron spectrum is harder and ensures better safety. At present, China is carrying out research on ADS.

7.2. High-level radioactive waste disposal

Fission product has high concentration radio-nuclide content (4 × 10¹⁰  Bq L⁻¹ ), large (2 kW m⁻¹ ) heat release, and nuclides with great toxicity, which accounts for 1% of all waste volumes, but has 99% of the total amount of radioactivity. High-level radioactive waste through solidification is generated with three heavy engineering barriers: the glass body, the waste tank, and the cushion material, which are used to stop water and to prevent radio-nuclide migration and burring in the deep formation isolated with the biosphere.

Nuclear power plant fuel is strictly controlled so it has fewer safety issues; its waste products are much less than coal and other wastes. Moreover, the glass and three heavy engineering barrier treatment, along with the ultimate disposal of the deep formation, will not bring harm to the environment and to humans.

China attaches great importance to the treatment and disposal of nuclear waste; thus, a spent-fuel pilot reprocessing plant has already been put into operation, while demonstration and commercial large-scale spent-fuel reprocessing plants are under construction or planning. In the latter, long-lived high-level radioactive waste can be transmuted in the fast neutron reactor or ADS. Moreover, demonstration and commercial fast neutron reactors are being constructed or planning, while research on ADS is at parallel with those carried out with the rest of the world. Finally, high waste vitrification and final disposal are being examined, and for time being spent-fuel is safely stored in the spent-fuel pools of nuclear power plants.

7.3. Decommissioning nuclear power plants

According to the state standards (GB/T 19597–2004) provisions, the decommissioning of nuclear power plants must be strictly carried out (SAC and AQSIQ, 2004 ). The decommissioning depth is divided into three grades. Grade1: removal of all nuclear fuels and monitoring sequestration; Grade 2: decontamination of part or all of its nuclear facilities, followed by the demolition of decontamination targets; Grade 3: removal of all of nuclear facilities, equipment, field, structure (building).

Decommissioning costs generally comprise 10%–20% of total infrastructure costs. As no decommissioning of nuclear power plant has yet to be reported internationally, this value is likely to increase. Within the operational life of nuclear power plants (40–60 years), the 15 years is generally devoted to debt service; afterwards, its profit rate is expected to increase annually. Hence, there is enough time for power plants to accumulate their respective decommissioning funds.

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