Among the preliminary results from the winter drilling programme, the company intersected 3.5m at 0.94% equivalent-uranium, including 1m at 2.7% eU3O8 1km north-east of Gryphon.

It also hit 5.6m at 0.55% eU3O8, including 1m at 2.3%, 600m north-east of Gryphon.

The company increased Gryphon's indicated resource by 88% in January, which provided an essential boost to the established Phoenix deposit, and took Wheeler's indicated resource to 132.1 million pounds U3O8 at an average grade of 3.3%.  

Denison has described Wheeler as the largest undeveloped high-grade uranium project in the eastern portion of the Athabasca Basin region and said it planned to test other regional targets in a summer programme.

"The last time Denison undertook any significant regional exploration on Wheeler was in 2014, which resulted in the discovery of Gryphon," vice president of exploration Dale Verran said.

Denison upped its funding to 75% of joint venture expenses in 2017 and 2018 to increase its Wheeler stake to about 66%.

It had increased its interest from 60% to 63.3% in December, with Cameco holding 26.7% and JCU Exploration 10%.

A prefeasibility study is slated for this year to build on a 2016 preliminary economic assessment which put total capex at C$560 million (US$443 million) with a pre-tax IRR of 20.4% based on the then-long-term uranium price of US$44 per pound.

Denison had C$41.4 million (US$32.8 million) at the end of December in cash, equivalents and short-term investments.

Its shares closed 1c higher yesterday to 65c, a midpoint in its 52-week range of 50-82c.