The total Ambassador indicated and inferred resource has increased to 30.3 million tonnes at 590 parts per million uranium oxide for 39.2 million pounds of contained uranium oxide.

While contained metal is only up by 3%, the amount of indicated material has jumped by 45% to 80% of the Ambassador resource.

Ambassador accounts for more than half of Mulga Rock’s total resource of 66.5Mt at 520 ppm uranium oxide for 76.2Mlb of contained uranium oxide.

Around 44% is in the indicated category at an aggregate grade of 720ppm.

Vimy managing director Mike Young said the resource upgrade was a critical milestone for the current DFS, with updates for the Shogun and Emperor deposits to follow shortly.

“We are currently working on the ore reserve for Ambassador and expect this to increase markedly and this will underpin future project financing and offtake contract discussions,” he said.

“The DFS is progressing on schedule and on budget and the project team is doing a stellar job. We are on track to be the first uranium mine in Western Australia.”

Ambassador has a current reserve of 13.9Mt at 660ppm uranium oxide for 20.2Mlb.

The company envisages mining the Princess deposit, which has a reserve of 1.3Mt at 640ppm for 1.8Mlb uranium oxide, first, before moving to Ambassador.

The November 2015 prefeasibility study outlined a 17-year operation, with the current reserve to underpin the first six years of production.

The project has capital costs of $US254 million, a net present value of $A431 million, a 25% internal rate of return, and a payback period of 3.9 years, based on a $US65 per pound uranium price.

The uranium spot price is languishing at below $30/lb but Vimy is aiming to time the completion of the DFS early next year for an expected improvement in conditions.

Shares in Vimy dropped A1c to 34c.