Along with coal, nuclear-produced electricity is getting added attention in the wake of energy shortages in the western U.S. and rising gas prices everywhere. More than a few Californians are wondering why they ever wanted to shut down the Rancho Seco nuclear plant 12 years ago, and some have even suggested re-opening it. The Sacramento Municipal Utility District (SMUD) closed Rancho Seco in 1989 after voters demanded its shutdown.
But since brownouts and the threat of blackouts have become commonplace in California, some people have wondered whether the nuclear plant couldn’t be restored to service. SMUD spokeswoman Dace Udris said the utility district received about 15 e-mails over a six week period asking if it was possible. The answer is “no way.”
In terms of the components needed to make power, essentially none remain according to Jim Shelter, SMUD’s assistant general manager. SMUD spent more than $200 million on decommissioning. All the steam conversion equipment, turbines, pipes and valves have been removed and shipped off for burial and disposal. SMUD’s current plans for the Rancho Seco site are to use the land, water rights and ties to the statewide electric grid to build as many as four new gas-fired units.
Clearly, any new plans would incorporate technology somewhat different than the boiling water and pressurized water systems comprising the U.S. commercial nuclear energy fleet. Among such new technologies is the pebble bed modular reactor currently being advanced by Eskom. The company hopes to build a plant in South Africa. Pennsylvania-based Exelon has a minority stake in the project and is engaged in preliminary discussions with the NRC about importing the design to America.
The pebble bed design uses helium rather than water to cool the reactor and spin the turbines. The fuel core is designed to withstand temperatures up to 2,900 F – far greater than conventional water-cooled plants – virtually eliminating the risk of meltdown. Fuel is contained in beads a millimeter in diameter. One thousand, five hundred beads are mixed with graphite and covered with carbon to form a sphere the size of a tennis ball. About 310,000 spheres are loaded into the fuel core. They’re checked every few months. Damaged or spent balls are removed; the rest are returned for another round. When Exelon introduced the pebble bed modular reactor to the NRC in January, the presentation attracted such a large crowd some people had to sit on the floor.