In July 2007, all seven units at Japan’s Kashiwazaki Kariwa nuclear power station were shutdown for extensive inspections and minor repairs following an earthquake that registered a 6.8 on the Richter Scale. In May 2009, Unit 7 became the first of the seven to be restarted; it entered into full time commercial service on December 28, 2009.
Unit 6 is the second of the seven shutdown reactors to be restarted. It initially completed a full testing regime in September 2009, but then experienced a fault in the reactor control rod position indication system that required a a maintenance shutdown. Unit 6 has been operating continuously since January 6, 2010 and has been officially returned to commercial service as of January 19, 2010.
Replacing the power produced by each one of the 1315 MWe ABWR’s at Kashiwazaki Kariwa required burning approximately 245 million cubic feet of natural gas per day. Since Japan does not have significant indigenous supplies of that fuel, Tokyo Electric Power Co. (Tepco) purchased the fuel in the form of imported Liquified Natural Gas (LNG).
The available LNG market supply has now increased by a total of 490 million cubic feet compared to the period before any of the plants were restored to operation. TEPCO has not announced a schedule for restoration of the other five units on the site; each of those is a 1067 MWe boiling water reactor whose power output would require burning 200 million cubic feet per day of natural gas – a potential total of another 1 billion cubic feet per day of demand that should eventually be removed from the Asian LNG market.
Note 1: The assumption in the above computations is that the average heat rate of the replacement power plants used was 8,000 BTU/kw-hr. The most efficient natural gas plants can achieve a heat rate of approximately 6,000 BTU/kw-hr, but the backup power plants that are called into service to replace the output of existing plants are generally not the most modern and efficient.
Note 2: To put some perspective on the magnitude of the changes in LNG demand, Japan imported a total of 3135 billion cubic feet of natural gas in the form of LNG in 2006, the last complete year before the earth quake. Assuming a capacity factor at the station of 85%, the annual increase in Japanese LNG consumption attributable to the earthquake was 460 billion cubic feet. In 2006, the total world market was 7626 billion cubic feet.
Note 3: A useful source of conversions for the units used in commercial transactions of oil and gas products is at the following URL: http://www.eppo.go.th/ref/UNIT-OIL.html