Astronauts traveling to and from Mars get a dose that is enough to raise their cancer risk by about 3 percent.
Accident at research facility exposed 33 people to minor excess radiation.
New results from looking at the split-second after the Big Bang indicate the universe is 80 million years older than previously thought.
Women treated with even low doses of radiation for breast cancer are more likely to develop heart problems.
More than 300,000 people remain displaced by the triple disasters.
A federal judge has ruled that the Department of Homeland Security must release two safety reports on body-scanning machines.
For several weeks last year, the Earth was surrounded by an extra ring of radiation.
The cost of repairs and inspections at the San Onofre nuclear power plant jumped to more than $400 million.
New York City could make millions in the deal allowing Microsoft to sell the system to other agencies.
North Korea's neighbors bolstered military preparations, mobilized scientists to determine if Pyongyang's third nuclear test was as successful as the North claimed.
