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Commitments and Contingencies - Contingencies (Details) $ in Millions | 12 Months Ended |  |
--- | --- | --- | ---
Sep. 30, 2024 USD ($) reactors Units Procedures Insurance_layers | Sep. 30, 2023 USD ($) | Sep. 30, 2022 USD ($)
Contingencies |  |  |  |
Nuclear liability insurance |  | $ 500 |  |
Assessment from licensees for each licensed reactor |  | $ 166 |  |
Number of licensed reactors in US | reactors |  | 95 |  |
Nuclear accident assessment limitation per year per unit |  | $ 25 |  |
Number of licensed nuclear units | Units |  | 7 |  |
Maximum assessment per nuclear incident |  | $ 1,200 |  |
Total amount of protection available |  | $ 16,300 |  |
Number of layers until the U.S. Congress is required to take action | Insurance_layers |  | 2 |  |
Maximum amount of retrospective premiums |  | $ 114 |  |
Maximum idemnity if a covered accident tasks or keeps a nuclear unit offline |  | 490 |  |
Maximum amount of retrospective premiums |  | 44 |  |
Estimated future decommissioning cost | [1] | $ 10,806 | $ 7,489 | $ 7,162
Number of procedures for determining estimates for the costs of nuclear decommissioning | Procedures |  | 2 |  |
Estimated liability for cleanup and similar environmental work on a non-discounted basis |  | $ 15 | 16 |
Amount of insurance available for loss at any one site (bottom range) |  | 2,100 |  |
Amount of insurance available for loss at any one site (top range) |  | $ 2,800 |  |
Environmental Remediation |  |  |  |
Contingencies |  |  |  |
Accrual for Environmental Loss Contingencies, Significant Assumptions |  | 215 million |  |
Nuclear |  |  |  |
Contingencies |  |  |  |
Estimated future decommissioning cost |  | $ 3,814 | 3,808 | 3,643
Non-nuclear |  |  |  |
Contingencies |  |  |  |
Estimated future decommissioning cost |  | $ 6,992 | $ 3,681 | $ 3,519
[1] | (1) Includes $283 million and $272 million at September 30, 2024 and 2023, respectively, in Current liabilities.

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- Definition An assessment from licensees for each licensed nuclear reactor in the United States to fund the second layer, the Secondary Financial Program. + References No definition available. + Details
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