ENERGY Resources Australia was forced to buy more than 600 tonnes of uranium to meet commitments after the Ranger mine produced a shortfall of ore.

The company's December 2010 quarter review showed the mine produced only 3793 tonnes of uranium oxide last year - compared to 5240 tonnes the previous year.

Chief Financial Officer Steve Thibeault said the company had already warned 2010 would be a "year of two halves".

"We had lower grade because of access to the pit and because of the longer wet season and geological issues," he said.

In June last year, ERA predicted it would produce 4500 tonnes of uranium once it obtained access to the higher grade ore in the lower pit.

"When we had access to the bottom of the pit, it, the grade level, was not as we were expecting," Mr Thibeault said.

"Now, we have a better understanding of the quality of the ore."

Mr Thibeault said ERA was still contracted to supply uranium ore based on last year's projections and the company was forced to purchase the shortfall amount.

According to the quarter review, ERA also met its sales commitments through inventory management and flexibility of timing of shipments to customers and loans.

ERA is also preparing a feasibility study for the proposed heap leach facility at the Ranger mine. The draft environmental impact statement is expected to be released in the first half of this year.

And a proposal to develop the exploration decline is expected to be completed in the second quarter of this year.

ERA last month announced it expected a full-year 2010 profit after tax of between $45 and $55 million.

That compared with nearly $273 million in 2009, which was a record.

The slump was caused by having to buy yellowcake at a "slightly lower" average price.

There have also been some positives during the year.