LONDON, Sept 13 (Reuters) - British wholesale gas prices rose on Friday morning, supported by an increase in gas-for-power demand and uncertainty around Opal pipeline flows and French nuclear reactors.
* The day-ahead contract was up 1.70 pence at 30.50 p/therm by 0850 GMT.
* The within-day gas contract was up 2.10 p at 29.50 p/therm.
* Weaker wind generation has pushed gas-for-power demand up, helping to raise prompt prices, a UK gas market source said.
* Gas-for-power demand is expected to rise to 49 million cubic metres (mcm) on Friday and to 55 mcm/day on Monday. This is higher than intially forecast, Refintiv Eikon data showed.
* Peak wind generation is forecast at 7.9 gigawatts (GW) on Friday out of 12.1 GW metered capacity in Britain. This is expected to rise to almost 9 GW on Monday, Elexon data showed.
* Uncertainty around Russian flows via the Opal pipeline, as well around French nuclear reactors, continued to provide support to European gas prices, market sources said.
* "Until we get clarifiication on OPAL and French nuclear situation participants will continue to add to positions," one of them said.
* Opal flows were stable this morning, however, with no impact yet of the European Court of Justice ruling earlier this week to limit Russian producer's Gazprom's access to the pipeline.
* French nuclear power producer EDF was informed this week of anomalies in welds on some steam generators and components used in its reactors.
* The British gas system was slightly oversupplied in the morning, National Grid data showed.
* Liquefied natural gas send-out in Britain is expected to rise to 44 mcm/day, an 11 mcm increase from Thursday, with Britain expecting five cargoes by Oct. 1.
* October contract was up 0.25 p at 38.00 p/therm.
* Day-ahead gas price at the Dutch TTF hub was up 0.28 euro at 11.18 euros per megawatt hour (MWh), while the month-ahead inched up by 0.10 euro to 14.80 euros/MWh.
* Benchmark Dec-19 EU carbon contract fell by 0.20 euro at 26.23 euros per tonne. (Reporting by Ekaterina Kravtsova; editing by Nina Chestney)