buy jordans Nuclear experts say China has four nuc

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Fukushima why the


, for example, around the border of the radiation Nuclear Power Station, the state limit of 0.25 mSv, the actual measurement is 0.005 mSv. Cigarette smoked the equivalent of 0.001 mSv in 2005, measured 0.0047 mSv, equivalent to 5 cigarettes smoked.
Second, the flood control requirements. Design will take into account typhoons, tsunamis, sea level rise, storm, upstream barrier bursts, and the wave impact, beyond the probability of one-thousandth to determine. Factory floor elevation is higher than Jizhun Hong level.
Reporter: Many readers have a question, that is, since so many pre-built security measures, the face of unexpected accidents, Fukushima nuclear power plant why the final is still facing
of whether the appropriate measures?
cooling failure to export the waste heat,cheap jordans online, causing the reactor temperature, pressure increases, the continued loss of coolant, fuel exposed, the original is the inclusion of water and steam. Exposed to the fuel temperature is high, and usually the temperature of water vapor around 200 degrees, there is no cool down on to the thousands of degrees. 1000-2000 degrees circumstances, and partly below water, from a chemical reaction with the zirconium to produce hydrogen. A plant outside the containment, hydrogen plant to go to the top of concentration, a concentration of 10% of the time (usually at 4% or less), met oxygen in the air, a hydrogen explosion occurred. 12, No. 1 unit of hydrogen explosion, 14, explosion of hydrogen Unit 3, 15, 2 units of hydrogen explosion, which ripped through the plant to make plant bare.
China has four nuclear reactors to ensure the safety barrier, the first barrier for the fuel pellet and cladding. Nuclear fission produces more than 98% of radioactive material remain in the ceramic pellets of uranium dioxide is not released. The second barrier for the fuel cladding. Fuel pellets sealed in zirconium alloy shell package to prevent fuel and radioactive fission products into a loop in the water, which is completely closed, even if the gas is also confined here, there is some space left, and the zirconium tube fuel rods can handle the pressure, the maximum number of closed gas emissions is not enough to make it crack. The third barrier, and a loop for the pressure vessel pressure boundary. Posed by the nuclear fuel core enclosed in a steel pressure vessel, pressure vessel and the whole circuit is a high pressure, the radioactive material will not leak into the reactor building. The fourth barrier is the containment, is the concrete structure. The safety of shell diameter is 37 meters thick and almost 1 meter containment and tight steel Souza, a certain internal pressure, it does not damage the containment to prevent radioactive substances into the environment.

Ye Qi Zhen: nuclear power plant design, when the environment there are three basic requirements for security, the first reactor when the event of a failure of the reactor to stop. Second, the reactor heat to export. The only difference with the nuclear power plant where the boiler is the boiler stops burning to no energy, and up to red hot only, nuclear power plants continued to issue some heat, about 6.6% of the original power, but also to guide them out of the energy to continue cooling. Third, the inclusion in the containment of radioactive material. If you follow these three principles, even in the event of any accident, nor an impact on the environment. Fukushima did it first, but after two failed to do, and this is the problem it produces.
However, the first nuclear power plant design elevation of the seawall was 5.7 meters, while the earthquake triggered a tsunami in the Fukushima nuclear power plant area is 14 meters, which makes emergency engine room flooded, to stop running an hour later . At this time, instrumentation and control system for battery change, the design capacity of only last 8 hours.


to the three:

- Further reading


fourth serious accident prevention and mitigation. There are mobile plant explosion prevention measures hydrogen, a complete measurement system, once the high concentration of hydrogen to hydrogen elimination, and now the new design of the non-active hydrogen compound device. Emissions of radioactive gas through the filter, the radioactive wash. While quickly relieving the steam discharged into the containment, because China is a pressurized water reactor, the pressure is high if the second loop, we then secondary emissions of steam, the steam is not radioactive at this time, but also can cool the main circuit, the main circuit emissions are emissions in the security shell.
13 hours later, mobile generators arrive, but because the power distribution device at the bottom, was flooded, and can not be connected until March 12 turned 15 had not been made, a new power cord grafting to the pump power, but this time it was too late. Super-elevation design of the tsunami led to the plant power, no external power supply, no internal emergency power supply, full-time director of power, resulting in long-term core cooling means is not available. The second safety requirements, that is, heat export, in one hour after the lost.
Fukushima nuclear accident in Japan caused the topic is still subject to public attention. Today, we invited our nuclear power authority of the experts, the Chinese Academy of Engineering, Nuclear Group, CST, deputy director of the Ye Qi Zhen, to answer reader friends concerned about three issues: First, there are so many pre-built security measures, why Fukushima nuclear power plant end still facing a Second, Fukushima problems for the links, the design of nuclear power if there are appropriate measures? Third, rely on China to ensure the safety of nuclear reactors?
Reporter: Where is reflected in the benefits of nuclear energy? The four nuclear reactors in China is how to set the security barrier? The so-called nuclear power plant defense in depth strategy is how is it?


What is radioactive cesium?





after the earthquake, the first nuclear power plant safety systems Fukushima start correctly. First of all safe shutdown, safety injection system and the emergency core cooling system started immediately, in the case of loss of offsite power, the emergency diesel engines are normally started. That is, before the tsunami, the operation of nuclear power plants is normal. The first is shutdown, the second cooling system starts up, the heat export to.
Reporter: Fukushima nuclear power plant problems for those links, the design of nuclear power plants have appropriate security measures? Please explain.

defense in depth how to set up the system?
Editor's note

radioisotope of iodine, iodine and iodine -125 -131 is relatively large toxic radionuclides. Radioactive iodine into the blood, about 70% present in plasma, 30% soon transferred to the tissues and organs within the body and selectively concentrated in the thyroid. Therefore, the health hazards of radioactive iodine on thyroid damage mainly. Radioactive iodine is widely used in nuclear medicine diagnosis.
question two:
a total of 38 isotopes of cesium, in addition to a stable isotope of cesium -133, the rest are radioactive. Broke the news of radioactive cesium nuclear reactor operation and the main fission products produced.

Ye Qi Zhen: Nuclear power is clean energy, nuclear fission energy is controllable. One kilogram of uranium -235 fission energy released is equivalent to 2,400 tons of standard coal combustion energy. We are a million kilowatts of nuclear power as long as the additional 30 tons of fuel each year, the same power, thermal power plant burning 3.3 million tons of coal per year. A large number of nuclear power in reducing greenhouse gas emissions, a significant reduction in the pollution of the environment of carbon dioxide, sulfur dioxide and other gas emissions, also reduce the cinder, reducing the transport, so the advantages of nuclear energy is very prominent, is the strategic choice of China's energy development.
environment cesium -137 easily absorbed into the body, evenly distributed in the body; due to the release of cesium--137 γ-ray, it is easy to detect in vitro. Into the main body retention of radioactive cesium in the soft tissue in the body, particularly muscle, bone and fat in low concentrations; relatively high levels of radioactive cesium, when ingested can cause acute and chronic injury. Cesium -137 as γ radiation, for radiation breeding, storage of food irradiation.



issue a:
early mixed radioactive iodine is the main component of fission products in one of the explosions and reactor accidents, it is the main radionuclide pollution of the environment early.



What is radioactive iodine?
to defense in depth strategy of nuclear power plants, when running a set of control system, once the accident stopped to put the heap, and then there are other security systems to protect it. For example, the pressure vessel out of water, to supplement it with the safety injection system, high pressure inside the containment, resulting in a lot of steam, and a safety shower systems, spray water into the pressure down. Evaporator is no water, and boiled away, and with the auxiliary water supply system to add. (Reporter Hu Qifeng)



was said to have been shutdown, and how could it go wrong? Because just shutdown, the pile of spent fuel discharged into the pond, and waste heat,syracuse basketball jerseys 国防白皮书：中国海军注, just to pump a few percent of the heat. 1 hour after the earthquake, the water and there is no cooling, the water is open, at one atmosphere pressure, more than one degree of water to evaporation caused the water level quickly dropped. A few days later, each reactor has about 1 million kilowatts of heat. Ten thousand kilowatts of heat without cooling, then you can boil three hundred tons of water a day, so they use helicopters to spray water cooling plant fuel,######## coach handbags 审判员宣读文强案一审判决耗时近, but the effect is small.
of the construction of the PWR nuclear power plant, which all of the material and the occurrence of nuclear fission in contact with water, are isolated inside the containment, with the steam turbine generator is isolated, which with Japan BWR accident is different.



Third, the emergency power supply, 500 kV main network, but also has a 220,000-volt dedicated backup power supply. The design of each unit has two emergency diesel engines,splitrock timberland, one can guarantee the emergency power supply, and also consider setting up a dedicated backup external power supply.

us to look at the whole incident process. Fukushima nuclear power plant has six units first. Unit 1 is in accordance with 0.18g (g refers to ground acceleration of gravity) design (now nuclear power plant design is based on the intensity of ground acceleration measured with the conventional seismic intensity is different,buy jordans, according to ground acceleration can be compared to the strict principles of mechanics, to calculate the buildings, equipment, piping, etc. can not afford a seismic intensity),tripp jeans, and the remaining units at 0.45g or 0.46g design. March 11, Japan, earthquake triggered a tsunami. The 9 earthquake is equivalent to 0.52g, more than a design standard.


Ye Qi Zhen: the problems for the Fukushima nuclear power plants, nuclear power plant design in a large number of security measures: First, anti-seismic design. The safety of all involved in nuclear power plants, should be designed according to safe shutdown earthquake, this is the meaning of words, even the earthquake situation,coach outlet handbags 党报评论称中国坚持发展势头必需保持对外配合, I would also like to maintain the function of the system, the heap can stop. Therefore, the plant should be placed on the foundation of bedrock integrity, must be away from the fault,nike air 90, especially in the surface cracks or dislocation of the active fault, must not build nuclear power plants.