Seite - 91 - in Water, Energy, and Environment - A Primer

disposal/recycling process. Another approach for future nuclear power plantsmay be to use a different fuel cycle that produces and consumes its own high-level waste. Modular reactors are also beingdiscussed (100–300MWunits, as opposed to today’s standard 1000MW units) which in principle can be mass produced, be less capital intensive, and sealedwithout refueling for years to decades. Regardless, there will still be a waste problem that has to be addressed. Assuming that the problems associated with nuclear fission power can be addressed successfully, which is still not clear, society will have some choices to make. Renewable energy is well on its way to entering the energy mainstream as a carbon-free, distributed, and large energy source, and one possibility is an energy future, post-fossil fuels, where nuclear power and renewable energy coexist. Other possibilities are a nuclear future or a renewables future.Given the complex issues presented by nuclear power my clear preference has been and continues to be a future energy system based largely on renewable energy in itsmany forms (seeChapter 8). 7.2 NUCLEARFUSION Nuclear fusion, theprocess thatpowersourSunandotherstars, is consideredbymanytobethe ‘holygrail’ofenergysupply.Why? Thenumbers tell the story. 7.2.1 Fusion fundamentals Thebasicphysicsof fusion iswell knownandeasilyunderstood. When the nuclei of light elements (lighter than iron) are forced together, under extreme conditions of pressure and temperature, they will fuse – that is, form a heavier nucleus that is lighter than the combined mass of the two fusing nuclei. The mass that is lost is converted to energy according to e=mc2 (see Figure 7.3). Nuclearpower 91