Grand Gulf goes for big uprate

14 May 2010

US utility Entergy has awarded a contract to the Shaw Group to perform modifications at its single-unit Grand Gulf nuclear power plant in Mississippi that will increase the unit's generating capacity by almost 14%.


Grand Gulf (NRC)
Grand Gulf (Image: NRC)
Under the contract - worth $197 million - Shaw will provide engineering, procurement and construction services designed to add some 178 MWe of power generation to the 1297 MWe boiling water reactor (BWR). Engineering and procurement are underway, Shaw said, with construction to follow to install plant modifications in spring 2012. The uprate would make Grand Gulf the largest-generating nuclear reactor in the USA. Currently, the plant accounts for 22.3% of Mississippi's electricity generation.


Shaw has performed more than 60 uprate projects and studies on BWRs and pressurized water reactors (PWRs), adding more than 3000 MWe to the US grid.


In April 2009, Entergy Nuclear renewed its existing contract with the Shaw for the provision of nuclear maintenance services to its fleet of eleven reactors at nine nuclear power plants. Shaw said that its scope of work includes routine maintenance and modifications, refuelling outage services and capital construction. The value of the six-year contract was not disclosed.


Entergy owns eleven nuclear units at nine plant sites, primarily in northeastern and southern USA. The eleven nuclear units include five General Electric BWRs, three Combustion Engineering PWRs, one Babcock and Wilcox PWR, and two Westinghouse PWRs.


Uprate options
The NRC recognises three categories of power uprates:
'Measurement uncertainty recapture' power uprates, which involve implementing enhanced techniques for calculating reactor power and can typically increase reactor capacity by up to 2%;
'Stretch' power uprates, which usually involve changes to instrumentation settings but are within the design capacity of the plant and can typically add up to about 7% capacity; and
'Extended' power uprates, which involve significant modifications to major plant equipment and can result in up to 20% capacity increases.


According to the US Nuclear Regulatory Commission (NRC), which must approve changes in engineering at nuclear power plants, a survey of reactor licensees in December 2009 indicated that some 39 applications are likely to be submitted to the NRC over the next five years for power uprates totalling about 2419 MWe of new generating capacity.


Since 1977, the NRC has approved a total of 129 uprate projects which together have added some 5726 MWe of generating capacity at existing plants.


Researched and written

by World Nuclear News