Legacy of Chernobyl disaster left area uninhabitable

Today’s question:

Why is it that Hiroshima and Nagasaki were rebuilt and inhabited soon after the atomic bombs were dropped but Chernobyl cannot be inhabited for many, many decades?

Because as horrible as the events at Hiroshima and Nagasaki were, Chernobyl was on a different scale.

When the Hiroshima bomb exploded about 2,000 feet above the city, about 2 pounds of uranium underwent nuclear fission and released nearly 16 kilotons of explosive force. About 70,000 people were killed and 70,000 were injured. Seventy percent of the city’s buildings were destroyed and about 1,900 people have died of cancers attributable to the radiation release.

The bomb at Nagasaki was detonated at 1,650 feet and released 21 kilotons of explosive force from 2 pounds of plutonium. Somewhere between 45,000 and 70,000 died on the spot and another 75,000 were injured.

Compared with the 2 pounds at both cities, the meltdown at Chernobyl in 1986 released at least 7 tons of nuclear fuel into the atmosphere. And because the nuclear fuel melted, volatile radioisotopes were released, including 100 percent of its xenon and krypton, 50 percent of its radioactive iodine and between 20 and 40 percent of its cesium.

And while the two bombs that ended World War II exploded in the atmosphere several hundred feet above the Earth’s surface, the reactor at Chernobyl went off at ground level, contaminating

the soil over 90,000 square miles. Why are planets round?

They aren’t all perfectly round. Earth, like some other planets and many of us, has a bit of a bulge in the middle. Mercury and Venus are roundest of all, almost like marbles.

Planets grow as bits of space stuff bump into each other and hang on. As the hunk grows its gravity begins to pull in on itself from all sides, creating a spherical shape.

Have a question for Clay? Reach him at 602-444-8612 or clay.thompson@ arizonarepublic.com