Using a discounted cash flow methodology, this paper performs a detailed analysis of the current costs of electricity from two of the Department of Atomic Energy's heavy water reactors. It compares these costs to that from a recently constructed coal-based thermal power plant. The cost so computed is a sensitive function of the discount rate (a measure of the value of capital) used and the results show that for realistic values of the discount rate, electricity from coal-based thermal power stations is cheaper than nuclear energy.