Canada-based NexGen Energy Ltd (ASX:NXG) has seen its share price plunge more than 13% as it announced a blow-out in costs to bring its Rook I uranium project online, compared to what had been predicted in the feasibility study published three years ago. The company said pre-production capital costs for Rook I – Canada’s largest development-stage uranium play – were now set at $2.2 billion Canadian (US$1.58 billion). This represented an increase of C$310 million as a result of inflation, plus another C$590 million caused by project enhancements identified through advanced engineering and procu…