EDITOR’S note:

Dr. Yu Shen is an expert on nuclear energy safety and director of nuclear risk management for Emirates Nuclear Energy Corporation, a United Arab Emirates government-backed organization. Shanghai Daily reporter Li Xinran had an interview with him recently amid China’s ambitious plan to develop its nuclear energy.

Q: What is the future of energy use?

A: The uses of fossil fuels — no matter coal, oil or natural gas — are a major source of pollutants. Besides, they could be used up in one or two centuries pending their reserves. Furthermore we human beings have sped up energy consumption, which further makes fossil fuels a major disadvantage.

That’s why we have to diversify our energy resources. Solar power has a lot of advantages but it is not concentrated enough. Solar panels with a large surface are very expensive but the power generated is not so much. Wind power has geographic limitations. Some places have abundant wind, which could be part of the energy solution for some small countries. Geothermal energy and tidal power have limitations. From my perspective, nuclear power is not only indispensable but can also play a big role for energy use. It is clean and eco-friendly as long as no accident happens.

Q: If we adopt nuclear energy, what should we pay attention to?

A: Nuclear energy development has varied in different countries. But there are two major problems in common. One is the storage of spent nuclear fuel and the other is nuclear safety. A solution for the storage of spent fuel is still far away. Some old nuclear plants put radioactive waste in their spent fuel pools. That’s why when a new plant is being designed, its solution on how to cope with spent fuel should be considered. But I think China can handle it properly.

Now let’s talk about nuclear safety.

Use of nuclear power to produce electricity is not a new technology. But nuclear power plants function differently from fossil fuel power plants. Except for the reactor itself, a nuclear power station works like most coal- or gas-fired power stations. Both boil water to make steam, which drives turbine generators. But for a fossil fuel power plant like a gas-fired one, if you cut off the gas supply no more heat is released. But if you switch off the power of a nuclear plant, its reactor will still release decay heat. Decay heat will cause destruction if it cannot be taken away. That’s why nuclear plants are built with safety facilities that usually have nothing to do with electricity production.

Q: What can we learn from past major accidents?

A: The development of nuclear plants grew rapidly in 1970s and 1980s. It was not very expensive to build a nuclear plant at that time. It is also very clean if there is no nuclear leakage. Investors then could recoup a plant’s capital outlay in just 10 years. Private investment flocked to the sector.

But the Three Mile Island accident on March 28, 1979, changed people’s minds. A combination of stuck valves, misread gauges and poor decisions led to a partial meltdown of the reactor core of the nuclear power plant on the island and the release of radioactive gases into the atmosphere. Fortunately, the meltdown was held by the containment so the consequence was not very severe. But after that the United States stopped building new nuclear plants.

The Chernobyl disaster, the worst nuclear power plant accident in history in terms of cost and casualties, led to a great impact on the industry. A big problem is how to put radioactive materials in safe containment to prevent them from leaking after a meltdown.

Then the Fukushima Daiichi nuclear disaster made us reconsider the design phase of nuclear plants.

When a nuclear plant is designed, we must presume what could happen, for example, a loss-of-coolant accident. We must put all kinds of accidents into consideration, as well as solutions to prevent or mitigate them.

However, there could also be accidents beyond design basis. They are unlikely events but a nuclear plant’s capability to cope with them could be very weak. We have a way to access a plant’s safety level. We call it PRA, or probability risk assessment. According to the result, no matter how new or old a nuclear plant is, the key is the ability to deal with beyond design basis events. Most of the nuclear plants worldwide can probably handle design basis accidents but beyond design basis events are the real danger — for example, a prolonged station blackout.

Q: How has nuclear energy developed after Fukushima Daiichi disaster?

A: The Fukushima Daiichi accident was a typical beyond design basis accident. The designer never thought huge waves could be as high as 15 meters, which submerged the plant. After the accident, each country equipped with nuclear plants launched a thorough probe of their systems and facilities. Most of them, including South Korea and the US, took measures immediately to improve weaknesses.

Germany announced a halt to building new nuclear plants. We have EDMG, or extensive damage management guidelines. China did the same as other countries. Now we have set up an in-depth defense system, including portable generators and an emergency center to mitigate risks.

Q: What do you think about China’s nuclear energy plan?

A: China is building new nuclear plants that belong to the third generation. It has a lot of safety facilities to mitigate risks. They are part of a passive system that is not powered by electricity but relies on force of gravity or natural circulation. China is the first country to run a nuclear plant of this type.

The third-generation nuclear plant has a better layout for reactors, better human-computer interface to reduce human errors and a digital operating system instead of an analog operating system, as well as a dedicated system to mitigate severe accidents.

Electricity produced by nuclear plants is currently less than 2 percent of total output in China, compared with 20 percent in the US and about 80 percent in France. South Korea plans to have 40 percent of its power supply based on nuclear energy. China has gained a lot of experience on nuclear plant construction. It could be the world No. 1 or No. 2 in 20 years. But in the future when China becomes an industry giant, the problem it will face won’t be how much electricity its nuclear plants generate, but how its administrator regulates the industry and how its technicians manage a specific plant or cope with an accident.