US debates pros and cons of boosting the power output of its nuclear reactors

Los Angeles Times : The US nuclear industry has been turning up the power on old reactors—a little-publicized practice known as uprating—in order to avoid the financial risks, public anxiety, and political obstacles associated with the construction of new plants. The power boosts come from more potent fuel rods in the reactor core and, sometimes, more highly enriched uranium, writes Alan Zarembo and Ben Welsh for the Los Angeles Times. In the wake of the Japanese nuclear crisis, however, the practice is being scrutinized more closely by nuclear watchdogs and the US Nuclear Regulatory Commission’s advisory panel. They warn that, in an uprated reactor, more neutrons bombard the core, increasing stress on its steel shell; core temperatures are higher, lengthening the time to cool it during a shutdown; and water and steam flow at higher pressures, increasing corrosion of pipes, valves, and other parts. Nevertheless, nuclear industry officials and regulators claim that safety calculations are conservative and that even the biggest uprates fall far short of the power loads the reactors could actually handle.