Power Generation ＼ Nuclear Power Plant

Introduction
Although nuclear power generation is currently the secondary power generation method in Taiwan, the power generation is much lower than thermal power generation. In 2017, the power generation structure of Taiwan Power Company accounted for 9.3% of nuclear power generation and 82.6% of thermal power generation. There are four nuclear power plants in Taiwan, namely, the First Nuclear Power Plant (Shimen District, New Taipei City), the Second Nuclear Power Plant (Wanli District, New Taipei City), the Third Nuclear Power Plant (Hengchun Town, Pingtung County), and the Fourth Nuclear Power Plant (Gongxi District, New Taipei City). After Nuclear Plant 1, Nuclear Plant 2, and Nuclear Power Plant 3 were finished constructing, they joined the ranks of power generation. In the past, the nuclear power was the most important power generation mode in the power generation record of Taipower Company. It reached the highest in 1985, accounting for 52.4%. In the same year, the thermal power generation just accounted for 34.5%.

Theory
Nuclear power generation uses the energy generated by the uranium splitting reaction to operate. The control rod is used to control the speed of splitting. The chain reaction produces huge heat energy to make water into steam, and then drive the steam turbine and generator to generate electricity. Now there are two types of nuclear power generation: pressurized water and boiling water, nuclear plant 1 and nuclear plant 2 are “boiling water nuclear power plants”, and nuclear plant 3 is a “pressurized nuclear power plant.” The two principles are the same, but the “pressurized nuclear power plant” system is more complicated.

Hand drawing

Current Situation
◎Pros:
1.Low operation cost.
2.Suitable for power generation as a base load.
3.High safety stock.
4.No carbon and air pollutants during gernerating.

◎Cons:
1.The construction cost which is 112,584 yuan / kw is high.
2.The construction period (about 13 years) is long .
3.Nuclear waste must be disposed well and the place is hard to find.
4.The public has doubts about the safety of nuclear power.

Taipower Exhibit Center in Northern Taiwan
On November 27, 2018, we visited Taipower Exhibit Center in Northern Taiwan is next to the Second Nuclear Power Plant. The guide, Ms.Deng, introduced the rotor parts of nuclear power plant. When we visited the museum, she explained the operation mode of the nuclear power plant and the brief history of the development of Taiwan's electric power industry. Finally, she also received an exclusive interview for us.
The outdoor display is that the gas turbine rotor was eliminated from the nuclear power plant and weighed 139 metric tons, which is about the weight of two or three thousand people. When the unit is in operation, the steam will push the blades. The speed is very fast. It can be rotated 1800 times in one minute. There is a total of three gas turbine rotors in the nuclear power plant including two low-pressure gas turbine rotors and one high-pressure gas turbine rotor, and one more low-pressure gas turbine rotor which is in outdoor display.

There is a miniature model of the nuclear reactor in the center, which is 8 times smaller than the scale (1/2 of the scale), and 7 stories high for the real entity. The second nuclear plant uses a water boiler. The principle is like boiling water. When the water is boiled, the steam will rush up and force to push the reactor. In the middle of the nuclear reactor is a core with a fuel bundle (nuclear fuel). There are 624 fuel bundles in the reactor. The fuel rod in the fuel bundle can be used for 4 and a half to 6 years.
There are more than one hundred and forty cross-type control rods in the reactor. The control rod can control the rate of nuclear splitting rise or fall. The rate of nuclear splitting will affect the temperature and amount of steam. Finally, it will affect the amount of power generated, so the control rod can control power generation. In addition, if cold water is pumped in, the temperature will decrease to lead the amount of electricity low.

The automatic detection device can sense an earthquake. If an earthquake occurs, the control rod will automatically rise up slow the speed of nuclear splitting. When the earthquake reaches a certain level, the control rod will automatically rise up, and then the reactor will stop in as long as 3 seconds.

The water in the reactor core is heated and boiled, and the vapor rises up to the gas-water separator, separating the vapor from the water. And next, the vapor continues to rise, and then the water passes through the gas-water separator and returns to the core. The vapor rises to the steam dryer, and the water is filtered. Finally, the dried steam pushes the turbine rotor and then drives the generator to generate electricity. The fuel in the reactor core will exceed 1000 degrees Celsius and the steam will be 264 degrees, so the reactor needs water to adjust the temperature.

Nuclear Power Plant 1
We went to the simulation control center of Nuclear Power Plant 1 directly after visiting the North Exhibition Hall because Nuclear Power Plant 2 which is next to the North Exhibition Hall was undergoing overhaul and personnel training. We first met up with Lin,Na-Hung , the planning manager, on the first floor, and he gave us a short presentation. Doing the interview of the simulation center director, Huang,Ying-Chun. Eventually, we visited the analog control room at second floor.

◎Introduction
The first nuclear power plant began construction in 1971, and began to operate in 1978. The first operation license was in December, 2018 and is currently entering the decommissioning stage. The average electricity price of Taipower is 2.8 NTD per kilowatt, and the cost of nuclear power generation is 1.25 NTD, so the cost of nuclear power is relatively low.

The power generation of the Nuclear Power Plant 1 in recent years (provided by Taipower)

In the past few years, from 2007 to 2017, the nuclear plant has continued power generation. Before the annual power generation, the two machines can send 10 billion kWh of electricity. The figure shows that there is a significant change in power generation in 2015 and 2017. During the overhaul in 2015, the fuel handle of the machine no.1 fell off, so it was stopped generating electricity at that time. Because of the huge flood in June 2, 2017, the power line of the machine no.2 went wrong. As the result, it also stopped operating. The cycle of the machine no.2 is almost over, so now neither machine is generating electricity. The machine no.1 was decommissioned on December 6, 2018, and the machine no.2 was decommissioned on July 15, 2019 according to the plan of Taipower.
According to Enforcement Rules for the Implementation of Nuclear Reactor Facilities Regulation Act, the nuclear power plant will apply for three years before the decommissioning. Therefore, the First Nuclear Power Plant has filed a decommissioning application in November 2015. Now, there are four stages of the decommissioning process in 25 years. The first stage is the 8-year downtime transition, the second stage is the 12-year decommission, the third stage is the 3-year final state detection, and the fourth stage is the 2-year site recovery.
The current difficulty, the First Nuclear Power Plant has to face, is that the used fuel cannot be removed by the planned schedule. The spent fuel pool is full. Entering the decommissioning stage, but there is no way to empty the reactor. Thus, there is no way to enter the post-decommissioning process. In contrast, they can empty fuel in the reactor in just six months abroad. Although the nuclear power plant already has dry storage of spent fuel, New Taipei City government did not approve the use of dry storage because of the water conservation problem. Therefore, the decommissioning process stopped.

The reactor cannot be emptied now (provided by Taipower)

The dry storage equipment is basically a tub filled with burnt fuel. One tub can have 56 fuel bundles, and then they are shielded with cement and placed on a flat ground. The dry storage equipment will be monitored and protected seriously, and the temperature and radiation conditions will be monitored at any time. The data will be connected to the control room, Nuclear Safety Duty Center, and even the website of the headquarter, “Nuclear Power Insight.” At present, the First Nuclear Power Plant has to wait for New Taipei City Government’s permission to empty the spent fuel pool and enter the late stage of decommissioning officially.

The dry storage of spent fuel (provided by Taipower)

◎Analog Control Room
In order to provide a simulator training place, the First Power Plant built the simulation center. The simulator in the simulation center has been updated to the third generation. The third generation is unique because it can be connected via the Internet after the 2013 update. The simulator has a set of computers, and two instructor consoles to control the hard disk drive and floppy disk for personnel training. The people who must have a license to operate the unit, so those who want to take the license must train here first. Besides, the people with licenses must return to train every year, even the technical manager or the headmaster need to be trained here, too.

When we visited the analog control room, we saw a team of control room. Tsung-Cheng Wu, the duty manager, stood behind and was responsible for the operation and control of the entire unit, as well as the command. There are two people who stood in front of Mr. Wu. One is a reactor operator who is responsible for the operation of the knob and the reactor core, another one is a reactor assisting operator who is responsible for the keyboard and some auxiliary equipment. We watched the power outage after the simulated typhoon and the emergency response of the earthquake.

Suddenly, the control room lighted down and an alarm sounded, and the duty manager commanded the operators to control the complex panels. When the power failure loses external power, the emergency diesel generator will be turned on, and the power can be automatically started within ten seconds. After the Fukushima incident happened, the control room would also simulate the response to the emergency diesel generators after the earthquake. We understood that the normal operation of a power plant requires a lot of professional participation. It is also not easy to simulate many emergency situations after their drill.

Group photo at the end

◎Q and A
Ying-Chun Huang, director of the Analog Control Center, answered the questions as follows:

Q1：The reactor will be cooled by seawater, but the hot water it produces will be discharged into the sea at the same time. Will it affect the ocean?
A1：All nuclear power plants in Taiwan are built by the sea because seawater is used to cool the reactor. The efficiency of a power plant is about one-third, that is, one-third of the energy produced by the reactor is converted into electrical energy, and the other two-thirds become unusable heat. Thus, it does need a lot of cooling water which is seawater usually. Cooling water enters the generator, which cools the vapor after power generation into water, but the temperature of seawater will increase by about 10 degrees, and they are all out together. At the same time, the temperature of the discharged seawater will be monitored by the control room. There are regulations to prevent power plants from affecting marine life. Moreover, the discharge water of Nuclear Power Plant 1 is in line with government regulations.
Q2：What is the difference between radioactive materials used in nuclear power plants and atomic bombs and nuclear-powered submarines?
A2：Uranium is main raw material for both, but the biggest difference is the extent of concentration. The concentration of nuclear power plants is about 5%, while the atomic bomb is 95%, just like the difference between beer and sorghum. Low concentrations of uranium in nuclear power plants cannot be split by itself, and its chain reaction must be generated in the reactor to generate electricity. However, the atomic bomb is a rapid compression of uranium to cause a supercritical reaction, and its energy is released in a short time. Nuclear power plants are under the control of human beings, releasing the energy in the nucleus for the benefit of mankind, but the atomic bomb is a weapon. They are totally different in function, though they use the same materials.

Q3：How to deal with the radioactive waste of nuclear power plants?
A3：It is radioactive. Radwaste can’t be see or smell, but it is measured by radiation monitor. In fact, the current low-level radioactive waste monitors in Lanyu measure less than in Taipei. Under the control of the government, the value of the Lanyu waste yard monitor is harmless to the human body. The disposal of radioactive waste is best managed centrally in one place, otherwise it will cause environmental pollution. Nuclear power plants and related departments are dealing with radioactive waste, which will consider geographical conditions such as 300,000 years of stable geology, and Taiwan has this kind of location. However, Taipower nuclear project will face many challenges due to policy changes and anti-nuclear groups. The nuclear waste is placed in the factory, and people who work here have not been affected, nor affecting the surrounding residents. The government has a set of standards to monitor our work situation.

We can check radiation report in Taipower website