Word: thorium
(lookup in dictionary)
(lookup stats)
Dates: during 1960-1969
Sort By: most recent first
(reverse)
...year-old potsherd to a 19th century vase. The technique employs the radiation-measuring devices used at most atomic reactors and in hospital radiotherapy departments. It is based on the fact that most mineral substances buried in the earth absorb the natural radiation given off by uranium, potassium and thorium in the earth. The rate of radiation has been relatively constant in historical times, but all absorbed radiation is released when the substance is heated...
...bomb is far more deep-rooted than Canada's, has nonetheless raced to complete its own atomic facilities-and has a more advanced nuclear technology than China, despite the substantial Soviet assistance that Peking received in the 1950s. India refines its own reactor fuel from vast reserves of thorium in Kerala, Madras and Bihar, thus is not subject to international controls over its allotment. It is also the first non-nuclear power to have a diffusion plant actually producing weapons-grade fissionable material, at Trombay, near Bombay. The government of Lal Bahadur Shastri has made clear that it intends...
...Cape Kennedy a three-stage, 100-ft. Atlas-Agena rocket blasted downrange over the South Atlantic missile track in a perfect launch. Five minutes later, the protective shield, a redesigned shroud of magnesium thorium, was jettisoned right on schedule. Thirty-seven minutes after that, from a 115-mile-high parking orbit over the Indian Ocean, the rocket engine reignited, kicking the 575-lb. Mariner D payload toward Mars at the required speed-25,600 m.p.h. At week's end all was going well with Mariner D and its 138,-000 individual parts. But the spacecraft still has quite...
...more nuclear fuel than they consume. Present-model nuclear reactors operate through fission of scarce and costly uranium 235. Natural uranium is mostly U-238; less than 1% of it is U-235. Breeder reactors would convert nonfissionable U-238 into fissionable plutonium, or convert the fairly common element thorium into fissionable U-233 (neither plutonium nor U-233 is found in nature). A few days before the 20th anniversary of the first chain reaction, AEC announced that its experimental plutonium reactor had achieved a self-sustaining reaction, verifying that plutonium can be used as fuel in a power reactor...
...Pleistocene. Developed at the University of Miami by Dr. John Rosholt of the U.S. Geological Survey and Italian-born Dr. Cesare Emiliani, it depends on the fact that a tiny amount of uranium is dissolved in all sea water. When it slowly decays radioactively, it yields protoactinium 231 and thorium 230, both of which attach themselves to sediment particles and sink slowly to the bottom. There they in turn decay, but protoactinium 231 decays faster than thorium 230. The age of sediment on the ocean floor can therefore be determined by measuring the relative abundance of the two isotopes...