On August 25, 2025, the Federal Energy Regulatory Commission (“FERC”) granted NextEra Duane Arnold, LLC (“NEDA”) a waiver of certain sections of the Midcontinent Independent System Operator, Inc.’s (“MISO”) tariff to use MISO’s generating facility replacement process for the recommissioning of the Duane Arnold nuclear power facility (“Project”) in Palo, Iowa. The order also extends the Project’s commercial operation date to December 31, 2029.
Under MISO’s tariff, the generating facility replacement process is an expedited process under MISO’s standard generator interconnection queue framework to replace existing facilities with newer and more efficient facilities. This expedited process allows interconnection customers to submit a replacement request at the same point of interconnection (“POI”), or meet certain requirements to use a different POI, up to the total MW capacity of the existing interconnection service. If MISO determines no material adverse system impact will occur, the replacement can move forward. However, if MISO determines a material adverse impact will occur, the interconnection customer must move into the standard queue.
The Project is a 619 MW nuclear reactor that began operating in 1975. NEDA decommissioned the plant in 2020 due to challenging economic conditions for nuclear power. However, in response to increased data center demand, NEDA recently began the recommissioning process. Since decommissioning, NEDA initiated the development of solar generating facilities adjacent to the site, executing several Generator Interconnection Agreements (GIAs) under its subsidiary companies.
NEDA’s waiver request sought permission to consolidate the interconnection rights of these solar GIAs and an affiliate GIA into a single POI at the 161 kV voltage level, and to extend their commercial operation dates to align with the Project’s new target operation date. In support of its request, NEDA argued that: (1) as an upstream owner and affiliate, it was not eligible to submit the replacement facility request or consolidate interconnection rights under the tariff; (2) it needed to transfer interconnection service from 345 kV to 161 kV, which is standard for nuclear facilities and shown by internal studies to be electrically equivalent; and (3) it could not meet existing commercial operation deadlines due to long lead times for equipment and extensive regulatory approvals and licensing. MISO supported these the technical findings.
FERC granted NEDA’s waiver request, finding: (a) NEDA acted in good faith by investing significant capital and securing interconnection rights to support the timely and cost-effective recommissioning of the Project; (b) the waiver was limited in scope as a one-time request applying only to this discrete nuclear facility; (c) the waiver addressed concrete problems, including the risk of losing existing interconnection rights and facing costly delays if forced into the standard queue; and (d) the waiver would not have undesirable consequences for third parties, as MISO’s studies confirmed no material adverse impact on the transmission system and NEDA committed to maintaining cost responsibility for required upgrades. FERC rejected arguments alleging the waiver would harm solar projects or ratepayers, finding those concerns speculative and unsupported by the record, and emphasized that the efficient restart of the Project would help meet urgent regional electricity demand.
A copy of the order, issued in Docket No. ER25-2989-000, can be found here.