Thomas wrote:George,
since you are clearly better informed about nuclear energy than I am, could you perhaps enlighten me on the following point? When I discuss nuclear power with environmentalists, one inevitable conversation pattern that emerges goes like this: I say that "nuclear power plants don't emit any pollutants during normal operation, so that's an environmental reason to support them". The environmentalist replies: "Maybe so, but you have to look at the whole process of building the plant and tearing it down after it reached the end of its life. These processes are not emission free, so your point doesn't hold." My response: "Maybe not, but are you sure these emissions are larger than when you build and tear down coal, oil, and gas plants? But even if they are, I'd be surprised if this changed the whole-life balance between the different types of power plant." At this point, we usually change the subject because neither side has the data to tell either way. Do you? And if so, can you tell me how total lifetime emissions compare between the different types of power plant?
Well-posed questions, and very insightful. I advise you to continue to rely on your intuition and powers of analysis.
A nuclear power plant is identical to a coal or gas fired plant of the same electrical capacity in many respects.
Both will have the same steam systems , turbines, and electrical transmission systems.
Both will have similar cooling water systems for removal of the waste heat from the steam condensers. The nuclear plant will need more cooling water because it discharges about 50% more heat at low temperatures (approx. 60 deg C) per unit of electrical power produced. (This heat can be captured and used to distill fresh water or many other uses).
Instead of a coal yard or gas line and fuel-fired boilers, the Nuclear plant will have a containment building which houses the reactor, coolant pumps, ion exchangers, and pressurizer - all for the closed circuit, high pressure primary coolant system, plus a heat exchanger (or "steam generator") in which heat is transferred from the high pressure primary coolant to the lower pressure steam system. The primary differential impact is here.
The environmental effect of the manufacture of the added high strength vessels and piping for the nuclear plant is small in that it is (1) but an incremental difference in what are already large industrial facilities; and (2) only done once and lasts the 50-year life of the plant. The same observation can be made for the eventual disassembly and teardown of the plants. (Excluding the disposition of the spent nuclear fuel).
The environmental effect of the coal storage facility and the associated mining and transport of the coal is usually left out of the analysis by environmentalists for self-serving reasons. Loose coal adds particulate to the atmosphere and evolves a good deal of CO2 just while it sits there, not to mention the mining and transport. Gas is better, but consider also that methane is about 27 times as potent a greenhouse gas as CO2 and visualuize the leakage from all those miles of pipelines.
The biggest negative for Nuclear plants is the mining, processing, manufacture, and disposal of the nuclear fuel. Presumably this should compare to the coal/gas cycle noted above. The mining and transport of uranium ore is hardly different than many other minerals and materials commonly used. The processing for enrichment and disposal of spent nuclear fuel does have a significant impact, mostly associated with (1) disposal of spent fuel; and (2) the construction & operation of the associated industrial plant. Assuming you believe that safe solutions can be found for the disposition of the spent fuel and related high-level waste (this is mostly an emotional issue) the environmental impact of the nuclear fuel cycle is less than that for coal (on either a human health risk or economic cost basis). Much depends on whether or not you suscribe to the hyperbole that often surrounds these subjects. Uranium enrichment involves substantial use of fluorine - uranium hexafluoride is the medium commonly used in the process. It is a very corrosive gas, and, of course the fluorine is a very reactive (but ubiquitous) chemical. However these issues are no more significant or difficult to manage than hundreds of like industrial processes. It is also important to consider the differences in volume & mass of the fuel required. Fewer than 1000Kg of nuclear fuel (a mixture of U-235 and other materials) will power an aircraft carrier for its entire 50 year life. A conventionally powered carrier will consume about 1,400 times that mass of petroleum every day!
The U.S. government has heavily taxed nuclear plant operators for the last twenty-five years for the construction of the waste depository, which it has still not opened. ( the operators must also pay for "temporary" storage) In addition plant operators are required to set aside financial reserves to in effect bond the costs of end-of-life plant demolition. No such concurrent costs are imposed on operators of fossil-fueledA plants. Despite this today most nuclear plants in the U.S. produce power at an lower unit cost than their fossil fuel counterparts. Most utilities operate their nuclear plants at 95+ percent capacity for base load and cycle their fossil fuel plants for diurnal load cycles (generally gas turbine plants are used to meet peak power requirements).
Finally a nuclear plant will operate throughout its life emitting zero SO2, zero NOX, zero particulate and zero CO2 into the atmosphere.
Forgive me if I went on too long. I can spit this stuff out almost as well as you do economics. (Reminds me - please go back to the Friedman avatar!)