Reactor vessel heads on the move

24 June 2009

A new reactor pressure vessel head was shipped from Kobe, Japan bound for Texas today. Meanwhile another is inching its way across California.


The massive component, five metres across, ten metres high and weighing 100 tonnes, was manufactured by Mitsubishi Heavy Industries (MHI) at its Kobe shipyard for use at the first reactor at the South Texas Project nuclear power plant.


MHI said it will also be providing a replacement vessel head for the other STP reactor in February next year as part of a double order placed in 2006. The two units began generating electricity 20 years ago and provide about 7.5% of power in the state, owner STPEGS said.


STPEGS is replacing the reactor vessel heads in order to maintain reliable and continuous operation of the reactors. Among the highest performing in the USA, the plant had a 98.87% capacity factor between 2006 and 2008 the company said. This was down to four 'breaker-to-breaker' runs, where the reactors operated continuously between refuelling stops about 18 months apart.


Orders like STPEG's have helped to boost MHI's books to show 19 replacement reactor vessel heads and 28 replacement steam generators for pressurized water reactors around the world. The orders came in as utilities managed aging issues at their plants. As well as helping to extend the lifespans of nuclear power plants, replacement steam generators and steam turbines can usually increase power output at the same time, making them very economic.


Another reactor vessel head is currently travelling across the US state of California towards the Palo Verde nuclear power plant.


Ramon Perez of the California Highway Patrol told the Desert Sun newspaper that the transport could only move at 4-5 miles per hour (6-8 km/h), the driver can only work for ten hours on each shift and it can only travel at night.


Having left the town of Banning the previous evening, "I'd say by the end of his shift, he'll be parking it somewhere north of Palm Springs," said Perez, indicating one further night of travel before arrival at Palo Verde.