A. Korean nuclear plant collapses

Since 2006, North Korea has conducted at least six nuclear tests from this center.

According to the BBC, after the last test in September last year, several consecutive defeats were recorded in Kungi ri. Geologists say that these effects were caused by a part of the inside of the hill inside the examination center collapsed.

Before a possible historic meeting with South Korea and the United States, North Korea's leader Kim Jong Un ordered to suspend the activities of nuclear tests and ballistic missiles in an unprecedented announcement on Saturday. A few days later, Chinese scientists feared the current situation of Pongi Rei.

University of Science and Technology of China (USTC), the research paper is to be published in the journal Geophysical Research Letters of the American Geophysical Union, a BBC report said.

Researchers say, after a half-an-hour of September's nuclear tests, a 'stupid building collapses in a vertical position'.

The location of the stool re-examination center is located in the north-eastern mountainous region of North Korea. Under the Mantaap mountain, the tunnel was used to pull down the tunnel.

There is also a summary of one page of the research on the USTC website. It has been said, "Due to the reduction of the underground management capabilities of Mantap hill, the future can not be used as a nuclear test center," he said.

The final peer-review paper, however, did not end the study. Instead of the previous words, it has been said, "After the collapse, the testing center should be continuously monitoring whether radioactive material is spreading."

The researcher's head professor Wen Linings told the Wall Street Journal that no published decision was made in the published article on the utility usage.

He did not tell the reason why it was avoided.

With the findings of the USTC study, the concept of Jillian Earthquake Agency, published in the same journal last month, is quite similar.

Jillian Earthquake said that the explosion in the test center caused new cavity and rock chimney damage.

No explanation was made about the usefulness of the use of the ring ray after the explosion and collapse in their paper.

Observers had already feared the tunnel collapse within the Mantap hills. Chinese scientists also expressed concern over the large scale nuclear test in September.

US Geological Survey Organization USGS recorded a quake in the 8th minute of North Korea's most powerful nuclear test.

After recording the two defeats in the area at the end of December, the company also gave their concerns about the permanency of the mountain ranges.