Capital costs for a 1.5 million tonne per annum operation were estimated at $A473 million including a 5% ($22 million) contingency, in line with the $471 million envisaged in the September 2013 scoping study.

The cost includes extra risk-mitigating measures like a second mobile crusher and automated process control.

C1 cash costs are expected to be just $1.66 per pound of nickel after by-product credits, bettering the $1.75/lb previously estimated, while all-in sustaining cash costs are set to be just $2.32/lb.

Based on a $US10/lb nickel price, projected life of mine nickel revenue is expected to be $A4.53 billion and net cashflow is set to be $2.74 billion.

Every $US1/lb rise in the nickel price is expected to equate to $A434 million in net cashflow.

The current nickel price is around $US8.75/lb.

The maiden probable ore reserve for Nova is 13.1 million tonnes at 2.1% nickel, 0.9% copper and 0.07% cobalt for 273,000t nickel, 112,000t copper and 9000t cobalt, based on a $7.44/lb nickel price.

The reserve represents a 93% conversion rate from the indicated resource and is close to the scoping study mining inventory of 276,000t.

Nova is set to produce 285,000t nickel over 10 years, or 26,000t nickel, 11,500t copper and 850t cobalt per annum in two separate concentrates.

Sirius managing director Mark Bennett described the DFS as "exceptional" with several aspects bettering the scoping study figures.

"Metrics such as the high resource-reserve conversion rate, the very low forecast C1 cash costs and all-in sustaining cash costs and the large projected net cashflow all support the low risk and the world-class nature of the project," he said.

"To be able to deliver such an outstanding DFS result on time and in less than two years since drilling the discovery hole is a testament to the outstanding quality of the Nova asset and our people.

"We are now in a position to develop this project as 100% owner at a time when the nickel market is forecast to be stronger for longer.

"This vindicates our counter-cyclic exploration approach, our ownership consolidation strategy and our long-term view of the nickel market."

Sirius is working on finalising a native title deal which will pave the way for the grant of the mining lease.

Financing and offtake talks are also well advanced with interested parties shortlisted.

At this stage, Sirius is aiming to start initial site works early next year with first ore extraction expected in the second quarter of 2016.

Plant commissioning and first concentrate production is expected in the fourth quarter of 2016, with the first shipment in the first quarter of 2017.

The company closed the June quarter with $A58.7 million cash - bettering its forecast of $46 million.

Sirius shares dropped 2.2% to $3.60.