文明のターンテーブルThe Turntable of Civilization

日本の時間、世界の時間。
The time of Japan, the time of the world

but there are as many genuine scholars in Japan as he does.

2020年01月30日 11時10分08秒 | 全般

The following is from a serialized column by Shohei Nagatsuji, published in the Sankei Shimbun yesterday.
I knew his name for the first time in this dissertation, but there are as many genuine scholars in Japan as he does.
Subscribers of the Asahi Shimbun and others who just watch NHK's Today's Close-up, etc., only know the real bastards.
I was delighted that he graduated from Kyoto University Faculty of Agriculture.
The next-generation nuclear power plant in Poland
The long-awaited Very High-Temperature Reactor
There are innovative reactors and high-temperature gas reactors in Japan that are extremely safe, with neither core melting nor hydrogen explosion.
The High-Temperature Engineering Test Reactor (HTTR) brought up under one's personal care by the Japan Atomic Energy Agency.
HTTR, located in Oarai-Cho, Ibaraki Prefecture, is the world's highest performance Very High-Temperature Reactor while being in the first stage of development.
Although very likely to be mistaken for thermal power, Very High-Temperature Reactor does not emit carbon dioxide and has the ability to produce electricity and hydrogen.
This next-generation nuclear power plant, which holds the key to the realization of a decarbonized society aimed at by the world, has taken a big "three steps" toward practical application.
The key to safety
A typical nuclear power plant is a light water reactor that takes out the heat of the reactor with water.
The VHTR, on the other hand, extracts reactor heat with helium gas.
In a pressurized water type or boiling water type light water reactor, the temperature of the steam to turn the turbine is 300 degrees, but in the case of VHTR, the gas turbine is turned with 950 degrees helium gas.
That's why it's called VHTR.
Because water is not used, it can be located in the desert.
The fuel is uranium, but its shape, core structure, and material are completely different from those of the light-water reactor.
As a result, inherent safety is provided, and the fission reaction stops spontaneously even if the pipe breaks and loses helium gas as a coolant.
After shutdown, the core cools down without operation.
Don't worry if you lose all the power.
This is VHTR.
Contribute to a hydrogen society
The "hop" for practical use is a breakthrough in hydrogen production.
Hydrogen is expected as a clean fuel, but when produced using natural gas or the like as a raw material, by-product carbon dioxide is generated.
Energy loss and cost are problems if made by electrolysis of water.
Hydrogen and oxygen can also be obtained by pyrolysis of water, but require an ultra-high temperature of 4,000 degrees Celsius.
In contrast, a chemical reaction that uses iodine and sulfur dioxide cyclically (IS method) can produce hydrogen from water at 900 degrees, which is where VHTR comes in.
Although the IS method was difficult to use due to the strong corrosiveness of the reaction solution, the JAEA VHTR research team succeeded in producing 30 liters per hour of hydrogen last January.
It achieved the world's longest continuous operation of 150 hours with equipment using ordinary piping for plants.
This breakthrough has opened the door to a true hydrogen society.
Upgrading fuel performance
The second step is to improve the performance of uranium fuel used in VHTR.
Through joint research between JAEA and the manufacturer's nuclear fuel industry, the fuel energy was raised to the level required for commercial VHTR, and its mass production technology was established.
It was reported at the Japan Atomic Energy Society last September.
The VHTR core, which is made up of graphite blocks, is loaded with a large number of cylinders called compacts (diameter 25 mm, height 40 mm), each compact contains about 13,000 spheres of 1-millimeter diameter spherical fuel.
A compact that is uniformly mixed with graphite powder and fired in a tubular fish-paste shape is compact.
Spherical fuel has a robust precision structure that encloses uranium dioxide in the center with four layers of ceramics.
Here is the best of technology.
The minute spherical fuel can withstand the load of generating combustion energy three times that of the past.
Survival appears overseas 
A breakthrough equivalent to a “jump” is the “VHTR R & D Cooperation Implementation Agreement” concluded in late September last year, with the JAEA and the Polish National Atomic Energy Research Center.
Poland is struggling to reduce carbon dioxide emissions due to the heavy use of coal in factories and other fuels.
Against this background, the Deputy Minister of Energy visited the HTTR in 2016 and has shown a strong interest in VHTR.
At present, the VHTR research and commercial reactor construction program has begun in the country.
Here, Japanese technology is provided in the form of joint research.
HTTR in Japan is the first stage of VHTR.
It has a thermal output of 30,000 kW and no generator. We want to move on to the next stage, but since the Fukushima accident, new plans in Japan are currently tricky.
Against this background, the government has proposed to promote the development of VHTR through international cooperation in the current Basic Energy Plan.
Therefore, cooperation in VHTR development in Poland is an opportunity for godsend for Japan.
The VHTR also has the characteristics of a small modular furnace suitable for distributed power generation.
After the Fukushima accident, the attention of the world is great.


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