On October 16 last year, Japan’s Chief Cabinet Secretary Kato Katsunobu announced that the Japanese Cabinet meeting would formally decide before the end of October to discharge the nuclear wastewater from Unit 1 of the Fukushima Nuclear Power Plant into the Pacific Ocean. By then, 1.23 million tons of nuclear wastewater will be discharged into the Pacific Ocean starting in 2022 and lasting for up to 30 years.
In fact, the first thing that came to my mind was confusion. Although the water is as high as 1.23 million tons, why does it take as long as 30 years to discharge?
In the past, I often heard people ask why Japan did not launch nuclear wastewater into space, but discharged it into the Pacific Ocean, causing harm to others and itself. Is Japan really planning to launch water into space during these 30 years of emissions? Of course not.
When it comes to launching into space, Japan’s aerospace strength is not inferior, and it ranks high among aerospace countries in the world. As for launching nuclear wastewater into space, this involves the field of launch vehicles. In terms of launch vehicles, Japan's strength is not inferior, but it is still a bit forward.
The most commonly mentioned feature of China's "Long March 5" is its use of a liquid hydrogen and liquid oxygen engine, which is the most technically difficult and most efficient rocket fuel combination. The first-stage liquid hydrogen and liquid oxygen engine of the "Long March 5" launch vehicle is called YF-77. In terms of performance, the thrust is 50 tons. Another important parameter is the highest specific impulse of 426 seconds. For now, let’s just understand specific impulse as a kind of efficiency, which means the higher the value, the better. So let’s take a look at Japan’s launch vehicles. Japan also has liquid hydrogen and liquid oxygen rockets, more than ten years earlier than us. The engine used by Japan's liquid hydrogen and liquid oxygen rockets is called LE-7A. This engine has a thrust of 84 tons and a specific impulse of 446 seconds. It can be seen that this Japanese engine is much better than ours.
It stands to reason that a good engine will lead to a good rocket. Japan’s rocket engines are better than ours, so Japan’s rockets should also be better than ours, but this is not the case.
The maximum carrying capacity of the "Long March 5" is about 25 tons, while Japan's most powerful launch vehicle, the H-2B, has a maximum carrying capacity of about 20 tons. The reason for this is that our rockets are larger in size, and the reason why our rockets are larger is because our boosters are more advanced. The booster used by Japan's H-2B rocket is a solid booster, which has a very low specific impulse. We use advanced liquid rocket boosters, which are larger in size. The reason why Japan does not use liquid boosters is that Japan does not have a high-thrust liquid rocket engine. Although the thrust of the LE-7A is 34 tons higher than that of the YF-77, the YF-100 engine used in the Long March 5 booster has a thrust that is 36 tons higher than that of the LE-7A.
I accidentally went off topic, so let’s get back to the topic. In other words, Japan can carry 20 tons of things into space at a time. In fact, the load capacity of 20 tons is already quite large, but the problem is that this load capacity is completely negligible in the face of the volume of nuclear wastewater in Japan.
So how many tons of nuclear wastewater are there in Japan?
In order to prevent nuclear wastewater from flowing out, Japan uses oversized tanks to store wastewater. There are more than 1,045 storage tanks, and the tonnage of nuclear wastewater has reached 1.23 million tons, and it continues to increase at a rate of 150 tons per day. You must know that a few years ago, the amount of nuclear wastewater produced every day was as high as more than 500 tons, and Japan also took various measures to build treatment systems and so on. Only then has the daily output of nuclear wastewater been reduced to the current 150 tons, and may be further reduced to 100 tons in the future. If a 20-ton rocket is used to launch, it will not be able to carry it all in a lifetime, and it will not even be able to carry the amount produced in one day.
In terms of nuclear wastewater storage capacity, Japan’s largest storage capacity is only about 1.37 million tons. According to estimates, at the current rate of adding 150 tons of contaminated water every day, nuclear wastewater will be released in September 2022. It was full. Therefore, it is urgent for Japan to take measures.
Of course, Japan does not directly emit emissions.
According to Japan's plan: first dilute the sewage with a large amount of non-polluting water to reduce the radioactive element content to a low enough level before discharging it, and extend the discharge time of nuclear sewage. A part of it will be discharged every year, and the total consumption will be It will be completed in 30 years. In terms of effectiveness, the total annual emissions do not even exceed the total requirements in my country's nuclear power plant standards.
So why do countries around the world still prevent Japan from doing this?
In fact, the problem is not how much harm Japan’s wastewater will cause to humans. Even if Japan does this, there will be no substantial direct harm at all. Because all nuclear power plants built along the coasts around the world can discharge nuclear wastewater directly into the sea as long as it meets the IAEA discharge standards. This is what the United States, China, Russia, the United Kingdom, and France do.
The real danger is that if these nuclear wastewater are discharged without meeting the standards, other countries will follow suit. In layman's terms, why can you drain water that does not meet the standard? Then I will do the same. Therefore, after Japan proposed the plan, the IAEA immediately intervened in the investigation and requested emissions regulation. The purpose of supervision is to ensure that the emission concentration, speed, and total amount comply with the standards set by the IAEA.
If you look at this matter purely, Japan is particularly aggrieved.
The tsunami caused by the earthquake that year was an unavoidable natural disaster. Nuclear wastewater cannot be discharged into the ocean and can only be stored for countermeasures. But Japan is a small country, so storing it all the time is not an option. After many years, no good solution has been thought of, and in 2018, the International Atomic Energy Agency urged Japan to solve the nuclear sewage problem as soon as possible.
This is a bit dumbfounding. Why doesn’t Japan want to deal with it? But the difficulty was too high, although five treatment options were later proposed, such as adding storage tanks, off-site storage, underground storage, and discharge into the sea or atmosphere. But none of them are feasible, either because the technology is not good enough, or other countries won’t let it.
In February 2020, the relevant Japanese committee issued a report. The report identifies the two most feasible options: "ocean emissions" and "water vapor", and the more feasible of the two is ocean emissions. That's why Japan announced its intention to discharge nuclear wastewater into the sea.
In fact, Japan still has the greatest impact by discharging nuclear wastewater into the ocean. First of all, this country relies on fisheries for a living, and nuclear wastewater will affect water quality and indirectly affect seafood. If seafood is contaminated, people will suffer.