UK GAS-Prices rise on high demand, nuclear outage extensions

Nov 7 (Reuters) - British wholesale gas prices rose on Tuesday as demand remained above the seasonal average and several nuclear reactor outages were extended. * The within-day gas price was up 0.10 pence at 51.00 pence per therm by 1037 GMT. * Day-ahead gas grew by 0.42 pence to 51.30 pence per therm. * Extended nuclear reactor outages in France and Britain, combined with high liquefied natural gas (LNG) prices and high demand, caused a rise in wholesale prices despite the system being oversupplied, traders said. * "Prices gained a lot more yesterday but temperatures now look a touch higher for next week," said one trader, explaining why Tuesday's price hike wasn't as high as the previous day's. * Average temperatures on Tuesday could reach 11 degrees Celsius in southern Britain and are expected to grow to 13 degrees on Friday, data from Britain's Met Office showed. * In France, several nuclear reactor outages have been extended, potentially increasing demand for power in the country. Britain is a key power exporter to France in times of high demand. * In Britain, ongoing planned outages at Britain's Sizewell B-1 and Sizewell B-2 nuclear reactors were also extended. * Britain's gas demand on Tuesday was 2.4 mcm higher than the seasonal normal demand, National Grid (LSE: NG.L - news) data showed. * Added to that, a 10-week rally in Asian spot liquefied natural gas prices has blown out their premium over British and European gas trading hub levels to more than $3 per million British thermal units, making it harder for Europe to attract supply. * Britain's gas system was oversupplied by 16.6 million cubic metres (mcm), with demand forecast at 271.6 mcm and supply at 288.2 mcm/day, National Grid data showed. * Gas supply from Norway to Britain on Tuesday reached almost the pipelines' maximum capacity at 136 mcm/day, up 9 mcm/day from Monday. * Peak wind power generation is forecast at 7.7 gigawatts (GW) on Tuesday but expected to fall to 6.2 GW on Wednesday, Elexon data showed. * Lower wind output typically results in higher demand from gas-to-power plants. * The December contract was up by 0.73 pence at 53.53 pence/therm. * In the Dutch gas market, the day-ahead gas price at the TTF hub grew by 0.20 euro to 19.13 euros per megawatt hour (MWh). * The benchmark Dec (Shanghai: 600875.SS - news) -17 EU carbon contract remained unchanged at 7.92 euros a tonne. * Thomson Reuters (Dusseldorf: TOC.DU - news) analyst view: http://emea1.apps.cp.extranet.thomsonreuters.biz/cms/?pageid=united-kingdom-gas (Reporting by Lefteris Karagiannopoulos in Oslo; editing by Nina Chestney)