The NDA have issued a statement on the estimated costs of decommissioning the parts of the UK nuclear industry that they are responsible for (here).
It shows total costs in the range £97 billion – £222 billion with a best estimate of £119 billion over 120 years. Discounted cost is put at £164 billion which is higher than the unadjusted cost because the NDA now use negative discounting rates as explaining in the supporting document from the Treasury (here) but more clearly in an Annex to the Annual Report (here).
The current value of £164 billion compares to £160.6 billion a year ago. This includes £1.3 billion being added to the estimated cost of completing the job. Inflation and changes to the discount rates being applied explains the rest of the increase.
So despite £3.243 billion being spent and an Annual Report talking of good progress the estimated cost to completion is more than it was at the start of the reporting period.
The Annual Report admits that £100 million was spent in compensation following the flawed contest for the Magnox contract.