Q. What is a hydrogen bomb?

A. Deuterium and tritium atoms (both heavy isotopes of hydrogen) fuse together when their mix is heated to up to 60 million degrees C with high pressure, releasing helium atoms and enormous amounts of energy in a process of so-called nuclear fusion, which releases light and energy. The hydrogen bomb or H-bomb is a nuclear fusion weapon. It is some 10 to 100 times more powerful than an atomic bomb. The Tsar Bomba, a hydrogen bomb developed by the Soviet Union in 1961, was said to be exploded with 58 megatons of TNT, 3,000 times more powerful than the atomic bomb dropped on Hiroshima, Japan. Heat from the detonation of the Tsar Bomba could be felt some 100 km away. Nuclear fusion occurs naturally in the sun, the energy source of the earth.

Q. How is it different from an atomic bomb?

A. Unlike a hydrogen bomb, an atomic bomb uses nuclear fission that occurs when a neutron strikes the nucleus of uranium or plutonium, splitting atomic nuclei and releasing a tremendous amount of energy. Atoms left unsplit release radiation, which can cause secondary damage. A hydrogen bomb produces relatively less radiation than a uranium or plutonium weapon. That’s why an atomic bomb is called dirty bomb, whereas H-bomb is called clean bomb.

Q. Is an atomic bomb needed when you detonate an H-bomb?

A. Nuclear fusion can only occur under extremely high temperatures like around 60 million degrees C or higher. Ordinary bombs cannot create such a high temperature condition. Kim Seung-pyung, a professor at the Department of Nuclear Engineering, Chosun University, said: “Heat for nuclear fusion can be produced only when you detonate uranium or plutonium.” Only five countries - the U.S., China, Russia, France and Britain - are known to have succeeded in hydrogen bomb experiments.

Q. Is it a real hydrogen bomb test conducted in North Korea?

A. Experts are skeptical about the claim by North Korea because the seismic wave was rather smaller than or similar to those from past three nuclear weapon tests conducted in North Korea. If a hydrogen bomb, some 10 to 100 times more powerful than an atomic bomb, explodes, the seismic strength should increase. It must be a magnitude-6.0 temblor or larger. But it was 4.8 on the Richter scale, lower than that recorded in the North’s third nuclear bomb test. For this reason, South Korea’s defense ministry and intelligence authorities are questioning the North’s claim, saying it might be a “boosted fission weapon,” a previous stage before advancing to a hydrogen bomb. A boosted fission weapon uses hydrogen and lithium that cause nuclear fusion. It’s rather a partial nuclear fusion, not a complete nuclear fusion. It’s two to five times more powerful than a nuclear bomb.

Q. How could North Korea get core raw materials to make the bomb?

A. Deuterium and tritium are key to the nuclear fusion. If the North’s claim is true, it means they already own deuterium and tritium. The nucleus of hydrogen contains one proton and no neutrons. But the nucleus of deuterium, a hydrogen isotope which is rare in nature, contains one proton and one neutron, whereas the nucleus of the far less common hydrogen isotope tritium contains one proton and two neutrons. The extra neutron in deuterium makes it heavier than normal hydrogen, hence it is called heavy hydrogen. It is difficult to get the isotopes from nature. South Korea`s Wolsung nuclear power plant uses heavy water. Deuterium can be derived from this heavy water and the neutron is absorbed by the lithium to produce tritium. But it is technically difficult to get tritium from deuterium. Some experts believe the North might bring tritium from elsewhere.

Q. Should we look out for radioactive fallout from the North’s nuclear test?

A. Korea Meteorological Administration said it is less likely radiation is detected in South Korea. Ko Yun-hwa, Administrator of Korea Meteorological Administration, explained the air flow at the time of the experiment showed its direction toward the Northern part of Japan passing the east of Gilju in North Korea. Therefore it is less likely radiation is detected across South Korea excluding its sea waters.

By Won Ho-sup and Lee Young-wook

[ⓒ Pulse by Maeil Business News Korea & mk.co.kr, All rights reserved]