cosmictraveler said:
They don't want another Chernoble to happen.
Let's remember Chernobyl, for a moment.
Chernobyl was a danger prone when it was built because of the graphite moderator in the RBMK design. This was a feature necessary for the soviets to use a lower grade of uranium than what is commonly found in western reactors when chernobyl was built in the late 1970s. The pressurized water reactors that were available since the 1950s are an inheriently safer design because water acts as the coolant, moderator, and reflector, and when it boils off, the reaction stops. The advances since then don't contribute the overall safety in this regard since PWRs are inherently safer from a conceptual standpoint and are immune to this kind of failure, because water is both the coolant and moderator - if the reactor overheats, the water boils off, and the reaction stops. The western reactors haven't learned a great deal from Chernobyl or advanced beyond it. We were never at risk of that sort of thing.
Also, the Chernobyl staff was well trained, they were just wantonly stupid when they systematically removed each of the 31 safety locks that were designed to prevent exactly that kind if runaway reaction.
cosmictraveler said:
They don't want another Three Mile Accident to happen.
It's been my experience that the people who use Three Mile Island as an example generally don't have a clue what happened there. A feedwater pump in the secondary loop tripped offline, and the loss of coolant immediately shut down both the turbines and the core. Without the cooling the natural decay heat in the core began causing the temperature and pressure to rise, and in and of itself this is not a bad thing since the reactor is designed for it. The pressurizer relief valve, that relieves pressure over 2300 psi in primary loop lifted when it was supposed to, but didn't reseat after relieving 3%-6% of the pressure. The valve stayed open continuing to vent pressure to the pressurizer relief tank (or quench tank), but the panel indicator showed that the valve had closed normally. Elsewhere in the plant, the emergency core cooling system failed to start properly because a valve was misaligned following a test two days earlier. That problem was recognized quickly and the valve was reopened in a matter of minutes, allowing the ECCS to operate normally. Now that the core and steam generator was being cooled, the pressure in the system dropped back to normal, and then continued to drop because of the open relief valve. The pressureizer, as it's supposed to, continued to pump water into the system to try and stabilize the pressure, but with the valve stuck open all it was doing was effectively pumping primary coolant water into the relief tank. Eventually the relief tank filled to capacity, and overflowed to an auxillary tank outside the containment building. That tank filled too and then overflowed into the wells of the building, and some of the vapor escaped through some fairly impressive vent filters. The vapor that did make it out was exposed to the overflow water, which was water from the pressureizer, which was water that at one point was exposed to primary coolant, which is circulated through a radioactive core. This is the leak that everyone is OMGOHSODANGEROUS about. In all it was just under 100 curies. The major constituents of the vented vapors were the non-condensable gasses common in most reactors, such as Xenon 135 and Krypton 85, and then a small about of dissolved Iodine -131.
Meanwhile, back at the core, the uncontrolled venting caused the core coolant pressure to drop and eventually some of the water started flashing into vapor. The situation was easily controllable since the operator could have flooded the system with more and more water, but the venting at the top of the pressureizer gave a false indication that the system was at capacity when in fact the water level continued to drop. Eventually a steam bubble formed in the core and delaminated some of the zirconium cladding on the fuel rods. The zirconium oxidized with the steam, and generated a hydrogen bubble at the top of the core. The top of the core was exposed to the hydrogen bubble for about 7 hours before system pressure was fully restored (thereby compressing the bubble) and was removed over the next few days by careful use of air-ejectors elsewhere in the cooling circuit. While exposed, some of the zirconium plate and upper fuel rods became hot enough to become kind of plastic and core damage was extensive, but there was no "meltdown"...especially since the jury is still out on what that word actually means.
PWRs are popular in the west because their fundamentals prevent that sort of thing from happening (despite what the Jane Fonda movies would have you beleive). I'm fairly knowledgeable on this subject and I'd be willing to discuss it at length. But taking this "because it just might" stance is foolish when it's not grounded in some kind of relavent facts.
As far as the average radiological contamination from TMI, it was just shy of 10 millirems, or the equivalent of a few chest X-rays. Oh the horror.
Detailed studies of the radiological consequences of the accident have been conducted by the NRC, the Environmental Protection Agency, the Department of Health, Education and Welfare (now Health and Human Services), the Department of Energy, and the State of Pennsylvania. Several independent studies have also been conducted. Estimates are that the average dose to about 2 million people in the area was about only about 1 millirem. To put this into context, exposure from a full set of chest x-rays is about 6 millirem. Compared to the natural radioactive background dose of about 100-125 millirem per year for the area, the collective dose to the community from the accident was very small. The maximum dose to a person at the site boundary would have been less than 100 millirem.
In the months following the accident, although questions were raised about possible adverse effects from radiation on human, animal, and plant life in the TMI area, none could be directly correlated to the accident. Thousands of environmental samples of air, water, milk, vegetation, soil, and foodstuffs were collected by various groups monitoring the area. Very low levels of radionuclides could be attributed to releases from the accident. However, comprehensive investigations and assessments by several well-respected organizations have concluded that in spite of serious damage to the reactor, most of the radiation was contained and that the actual release had negligible effects on the physical health of individuals or the environment.
http://www.nrc.gov/reading-rm/doc-collections/fact-sheets/3mile-isle.html
cosmictraveler said:
They are worried where the Radioactive waste is going to end up.
We already have many solutions. The Waste Isolation Pilot Project (WIPP) in New Mexico is supposed to house the stuff for a few thousand years in some fairly impressive salt/lime deposites. Supposedly the facility can be taking materials for several decades to come, but once it's full, I bet it won't be too much longer until we it up and do just what you propose: off to the sun, only with cheap rockets before the elevator.
And high level reactor waste is 99% inert after only 300 years. Yes, this is still a long time, but it's peanuts on a global time scale, and certainly less than the 4 billion years number that Greenpeace constantly spouts off about.
Also, for the general discussion, we really only need fission to hold us for the next, say, 100 years or so until we can get fusion going, and then wait for it be become cheap and prolific. As a matter of purely personal openion, I'd rather see a field of fission reactors tucked away in a quiet corner or the world and WIPP filling up fast than some idiot spoiling my desert horizons and valleys with a buch of fucking windmills, or doing something stupid to my bays so that they can get a few measely megawats out of it. I mean damn, these people are supposed to be the concervationists? They want to cover how many square miles in solar cells just so that they can have a clear concious while sitting in an air conditioned coffee house? Anyway, not meant to be inflamatory, just my feelings on it.
