The remote town of Galena, Alaska, which pays three times as much for electricity as the national average, is seriously considering a very unusual way to generate as much electricity as a clutch of diesels could provide. Recently, town officials initiated talks with the Nuclear Regulatory Commission (NRC) about installing a small nuclear reactor in the remote village of 700 people, which is 550 miles northwest of Anchorage.
Apparently, the cost of bringing fossil fuels to Galena—shipping diesel in by barge during the brief window when the Yukon River is not frozen over—is so great that the town fathers are desperate to find an alternative. One option they considered was building a small coal-fired plant, because there’s a coal seam about 10 miles away. But no one builds coal plants that are small and clean enough, and the cost of getting permits to open a new mine might make such a project impractical.
To Galena’s rescue has come: Toshiba. The company, which performs maintenance and repair work on conventional nuclear reactors around the world, is trying to develop a new reactor that would run almost unattended and put out 10 MW of power. Toshiba sees Galena as a test market for the reactor, which the company feels might be appealing to similarly isolated towns, factories, and mines. It even has offered Galena a free reactor—whose cost is estimated at $2,500/kW or $25 million—if the town would pay its estimated operating costs of around 10 cents/kWh.
So, while consortiums of reactor vendors laboriously file preliminary design applications with the NRC in the hope that America’s first new nuclear plant ordered since 1978 will be commissioned by 2010, Galena hopes it will have a micro-reactor up and running by then.
Toshiba calls its design the 4S reactor, for "super safe, small, and simple." It would be installed underground. In the event of a cooling system failure, heat would be dissipated through the earth. The reactor would have no complicated control rods moving through the core to control the flow of neutrons that sustain the chain reaction; instead, it would use reflector panels around the edge of the core. If the panels are removed, the density of neutrons becomes too low to sustain the chain reaction.
The 4S reactor would run on uranium enriched to 20%. That would allow it to run for 30 years without refueling, Toshiba claims. The design, which the company describes as "inherently safe," does have one risky feature. It uses liquid sodium rather than water to draw heat away from the core. Toshiba’s designers chose sodium so the reactor could run about 200 degrees hotter than conventional power reactors but still keep the coolant depressurized. The problem is that if sodium leaks, it burns.
According to Alan Levin of the Office of Nuclear Regulatory Research, it’s too early to guess how the NRC will approach licensing for this type of reactor. But he also noted that one of the earliest nuclear plant designs in the U.S. used liquid metal reactor technology. The 1.1-MW (thermal) sodium-potassium-cooled Experimental Breeder Reactor I (EBR-I), which started up in Idaho in 1951, was the first in the U.S. to produce electricity. That was followed by the 20-MW sodium-cooled fast reactor, EBR-II, which began operation in 1964 and ran for 30 years.