STP sets new US nuclear record

07 October 2008

The South Texas Project (STP) has set a new US nuclear industry record by completing four consecutive breaker-to-breaker production runs by repeatedly operating both its units continuously between refuellings.

South Texas Project 
The record-breaking STP plant
(Image: STPNOC)
The term "breaker-to-breaker" refers to closing an electrical breaker at the end of one refuelling outage as the plant begins producing electricity for the grid, then later opening the breaker to shut off power to the grid as the next refuelling outage begins. This can only be done with a high level of equipment reliability and overall plant performance.

During the past three-and-a-half years, STP's two pressurized water reactors (PWRs) have produced 65 TWh of electricity - more energy than any other two-unit nuclear power plant in the USA. The units produced some 7.5% of all electricity consumed in Texas over that period.

STP unit 1 operated continuously from April 2005 until October 2006, when it was stopped for refuelling. It then restarted in November 2006 and ran through to March 2008, when it was again refuelled. Unit 2 operated continuously from October 2005 to March 2007, and again from April 2007 until 5 October 2008, when it was shut down for routine maintenance and refuelling. The units generated 32.7 TWh and 32.3 TWh, respectively, during those production runs.

According to Nuclear Engineering International, STP unit 1 had an average load factor of 102.7% to the year ended March 2008, the highest worldwide. STP unit 2, meanwhile, had a load factor of 96.9%. The worldwide average over this period was 75.1%.

STP Nuclear Operating Company (STPNOC) said the reactors also achieved the lowest unsubsidized production cost among US nuclear power plants - 1.356 cents per kWh in 2006 - and the lowest fuel cost of all US power plants - 0.399 cents per kWh in 2000.

The twin-reactor plant produces some 2700 MWe. STP's reactors were brought on-line in August 1988 and June 1989. The facility is operated by STPNOC and owned by NRG Texas (44%), CPS Energy (40%) and Austin Energy (16%).