Sept 20 (Reuters) - Uranium prices are likely to extend a blistering rally and end the year more than 50% higher as mounting worries over climate change accelerate a global shift to cleaner sources of energy including nuclear power, analysts said.

Uranium spot prices are expected to climb to $75-$80 a pound by end-December, in a fitting finish to a year that has seen the metal rally about 36% to-date.

At current levels of around $66.25 a pound, prices are the highest since the 2011 Fukushima disaster. They had peaked at $140 a pound in 2007.

"The market has been slowly building higher prices as mining costs rise and nuclear generators look to build stocks to guard against increasingly risky supply-side issues," said SP Angel mining analyst John Meyer.

"We see prices rising year-on-year for next 10-20 years or till the world finds another source for large scale un-interruptible base load power with a low carbon footprint."

Demand from nuclear reactors was projected at 65,650 tonnes of elemental uranium (tU) this year, with the World Nuclear Association forecasting it to climb 28% by 2030 and nearly double by 2040 to 130,000 tU.

A push to improve energy security, particularly after Russia's invasion of Ukraine upended the global oil markets, has also stoked demand, while supplies remain constrained due to under-investment in new production, transportation risks from geopolitical uncertainties and monopoly of state-owned entities.

Meanwhile, utilities are racing to stock up and term contract volume so far this year exceeds 118 million pounds, the highest in over a decade, according to market research firm and consultancy UxC.