Nuclear Decommissioning Reserve Calculator
Federal law requires nuclear plant licensees to set aside funds over the plant's operating life so that money is available to safely decommission the reactor at end of life — and like any long-term savings goal, the earlier and more consistently a licensee contributes, the less they need to set aside each year, since investment returns do a growing share of the work. This calculator takes the estimated total decommissioning cost, the years remaining until decommissioning, the current trust fund balance, and an assumed fund investment return, then reports the future value of the current balance, the remaining future value needed, and the required annual sinking-fund contribution to close the gap. It pairs naturally with our SMR Levelized Cost of Electricity (LCOE) Calculator for the full capital-cost picture of a nuclear project, and our Nuclear Fuel Cost Calculator for the ongoing fuel-cost side of plant economics.
Individual reactor decommissioning cost estimates commonly range from roughly $500 million to $1.5 billion or more, depending on reactor size, type, and site-specific conditions.
The number of years left in the plant's operating life over which the trust fund continues to accumulate contributions and investment returns.
The amount already accumulated in the decommissioning trust fund today, which will continue to compound at the assumed investment return until decommissioning.
The average annual investment return the trust fund is assumed to earn. Decommissioning funds are accumulated over decades, so even modest differences in this assumption meaningfully change the required annual contribution.
current trust fund balance ($) × (1 + assumed fund investment return (%) ÷ 100)^years remaining
estimated total decommissioning cost ($) − future value of current trust fund balance ($)
remaining future value needed ($) × sinking fund factor
This is a simplified sinking-fund planning model, not a substitute for the actual NRC minimum decommissioning funding formula under 10 CFR 50.75, which specifies precise minimum amounts by reactor type and thermal power rating, escalated for inflation and adjusted through periodic reporting. Licensees must comply with the actual regulatory formula, not this illustrative calculation.
Results update live as you type. For planning and field-check estimates — always verify against applicable standards and equipment ratings.
How we calculate this →Decommissioning funding works like any long-term savings goal: the earlier and more consistently you contribute, the less you need to set aside each year, since investment returns do a growing share of the work over time. In this example, a $200 million existing trust fund balance, if left to compound at 5% for 20 years, grows to over $530 million on its own -- meaning the required additional annual contribution to reach an $800 million target is only about $8.15 million a year, not a simple $30 million/year linear split of the remaining gap.
How the nuclear decommissioning reserve is calculated
This calculator estimates how much a nuclear plant licensee must contribute each year to a decommissioning trust fund to reach a target decommissioning cost, accounting for the investment growth of both the existing balance and the ongoing contributions. Four quantities tie the calculation together.
Future Value of Current Trust Fund Balance ($) = Current Trust Fund Balance ($) × (1 + Assumed Fund Investment Return (%) ÷ 100)^(Years Remaining Until Decommissioning). The amount already in the trust fund today continues to compound at the assumed investment return for the remaining years of plant operation, so this step projects what the existing balance alone will grow to by the time decommissioning begins. At the defaults ($200 million current balance, 5% return, 20 years), that is 200,000,000 × 1.05^20 = 200,000,000 × 2.653297705 = $530,659,541.
Remaining Future Value Needed ($) = Estimated Total Decommissioning Cost ($) − Future Value of Current Trust Fund Balance ($). Subtracting the projected future value of the existing balance from the total target cost gives the shortfall that still has to be filled by future contributions. At the defaults ($800 million target, $530,659,541 future value of current balance), that is 800,000,000 − 530,659,541 = $269,340,459.
Sinking Fund Factor = (Assumed Fund Investment Return (%) ÷ 100) ÷ ((1 + Assumed Fund Investment Return (%) ÷ 100)^(Years Remaining Until Decommissioning) − 1). The sinking fund factor is the standard engineering-economics multiplier that converts a future lump-sum target into the equal annual payment needed to accumulate it, given a fixed investment return and a fixed number of years. At the defaults (5% return, 20 years), that is 0.05 ÷ (1.05^20 − 1) = 0.05 ÷ (2.653297705 − 1) = 0.05 ÷ 1.653297705 = 0.0302426.
Required Annual Contribution ($/year) = Remaining Future Value Needed ($) × Sinking Fund Factor. Multiplying the remaining shortfall by the sinking fund factor gives the equal annual contribution that, invested at the assumed return over the remaining years, will close the gap to the total decommissioning cost. At the defaults ($269,340,459 remaining, 0.0302426 factor), that is 269,340,459 × 0.0302426 = $8,143,566/year.
Two notes on the model. First, this is a simplified, illustrative sinking-fund planning model -- it assumes a constant investment return, level annual contributions, and a single lump-sum decommissioning cost at the end of the period; it is not a substitute for the actual NRC minimum decommissioning funding formula under 10 CFR 50.75, which specifies precise minimum amounts by reactor type and thermal power rating, escalated for inflation and adjusted through periodic reporting. Second, because decommissioning funds accumulate over decades, the assumed investment return is the single most consequential input: even a one-percentage-point change in the assumed return meaningfully shifts the future value of the existing balance and the required annual contribution, which is why NRC financial assurance requirements are periodically reviewed and adjusted. Data sources: NRC decommissioning funding regulations (10 CFR 50.75) and guidance documents; individual reactor decommissioning cost estimates from NRC case studies, EPRI (Electric Power Research Institute), and industry technical documentation; historical decommissioning fund investment returns from industry reports and financial data; decommissioning process timelines and scope from NRC licensing documents and completed decommissioning case studies. Verification: with defaults ($800M target, 20 years, $200M current balance, 5% return), Future Value of Current Trust Fund Balance = $530,659,541, Remaining Future Value Needed = $269,340,459, Required Annual Contribution = $8,143,566/year.