Matt Potter 6:30 p.m., May 5
- Community Blog
- As the Sun Cafe goes on
Update San Diego, 4/19/2011
A good story on the light rail systems developed in the U.S. and Globally. The U.S. is still behind. Trains between Shanghai and Beijing are moving at 302 mph. We could move from New York to Los Angeles in 41 minutes at 4000 mph.
Ref: Popular Science, May 2011 pp. 70
A good story on the Fukushima Daiichi's design and what is really going on over there.
Ref: Science 4/01/2011 pp. 24
Some high points.
1) Water level at the spent fuel storage pool for reactor #4.
2) There are 350 reactors Globally with the same pools.
3) #4 storage pool building is the area producing the most radiation.
4) Spent tubes of uranium pellets are kept under water to shield workers and the environment from radiation. Maybe the workers could use wet suites filled with water as protection?.
5) Tubes are made of Zirconium, Zircaloy-2 or Zircaloy-4.
6) Zirconium can burn eather with steam or oxygen at 800C temperature which releases hydrogen.
7) Hydrogen with oxygen will explode.
8) A 2006 study showed that with a heat-up after a loss of water-event could melt fuel - allowing the escape of volatile radio-nuclides including "a substantial fraction of the cesium" into the air.
9) Soil samples around the plant show the equivalent of 8E6 becquerels per sq meter of cesium near the plant.
Some notes on units.
Severt (Sv)- defined as the amount of radiation roughly equivalent in biologic effectiveness to one gray. 1mSv=10 ergs of energy of gamma radiation transferred to one gram of living tissue. This unit is recommended by the International Commission on Radiation Units and Measurements (ICRU) as a substitute for the rem, as the relative biologic effectiveness (RBE) of ionizing radiation is different for X rays, gamma rays and neutrons on living tissue.
gray- defined by the ICRU as equal approximately to the absorbed dose delivered when the energy per unit mass imparted to matter by ionizing radiation is 1 joule/kg. The gray replaced the rad which is not coherent with the SI system. 1gray=100rads.
Curie-defined by the ICRU as the activity of a quanity of a radioactive nuclide for which the number of nuclear transformation/sec=3.7E10 or the amount of material undergoing 3.7E10 disintegration/sec.
Radiation in the nuclear plants are too high for the workers to enter them. In unit #1 the readings were 49 mSv/hr and in unit #3, 57mSv/hr recorded by robots sent in to do the work. In the U.S. workers are not allowed in nuclear plants if the recorded radiation rates exceed 50 mSv/yr. Note hr and yr!.
Ref: San Diego Union-Tribune, 4/19/11 pp A6
Cesium-137 is used to kill cancer cells in cancer therapy.