Just after it connected for the first time to the grid, the Tennessee Valley Authority’s (TVA) 1,150-MW Watts Bar-2 nuclear generating unit in Spring City, TN, shut down automatically Sunday.
The unit shut after it experienced turbine system issues Sunday afternoon, TVA spokesman Scott Brooks said.
The federal power producer is troubleshooting the problem, and there is no schedule for when the unit might restart, Brooks said.
Watts Bar-2, the first new reactor to come online in the U.S. in two decades, first connected to the electricity grid Friday evening at 8:39 p.m., Brooks said. The unit achieved “first criticality” — a self-sustaining fission reaction taking place in the core of the reactor for the first time — on May 23, TVA said.
Watts Bar-2 is the first new power reactor to record initial criticality and connect to the grid for the first time in the U.S. since 1996, when the adjacent Watts Bar-1, with a similar net output, did the same. Construction of Watts Bar-2 began in the 1970s, but ended up suspended for two decades before TVA decided to complete it in 2007.
Watts Bar-2 had been operating at very low thermal power levels in May and not connected to the grid, TVA said.
The unit was at 14 percent of capacity most of last week, before reaching 18 percent of capacity early Saturday, according to the Nuclear Regulatory Commission’s (NRC) daily reactor status report. The unit was at 10 percent of capacity early Sunday before shutting down.
Initial connection to the grid will be at low power levels, with power rising incrementally over a period of weeks, TVA officials have said.
“Power ascension testing” will end up repeated several times and the unit will shut down after producing power to test safety systems, officials have said.
TVA said in a filing with the Securities and Exchange Commission May 3 it expects to declare commercial operation of the reactor, when testing is complete and steady-state operations are likely, sometime this summer.