SMR developments: April 2026
23 recorded developments dated April 2026: 3 permission or environmental decisions, 11 project developments, 1 announcement, 8 policy steps.
Entries are placed by their recorded date, not by when SMRMap added them. Entries dated only to a quarter or year are not assigned to a month. Each entry is dated when the development happened unless its label says otherwise, such as “Announced” or “Report dated”. A date recorded only to a month, quarter or year is shown that way. Targets are plans, not achievements or commitments.
Recorded developments
· Recorded development
DOE approves the Antares Mark-0 documented safety analysis #
DOE's Reactor Pilot Program update of July 2026 lists the Antares preliminary documented safety analysis as approved in January 2026 and the documented safety analysis as approved in April 2026, before zero-power criticality on 4 June 2026. The update gives months, not days. The slides do not reproduce the approval documents. A safety-analysis approval for a zero-power test does not authorize a later power reactor.
· Recorded development
Basemat module lifted into the Darlington BWRX-300 reactor building shaft #
In April 2026 the basemat module, the roughly 953-tonne foundation of the reactor building, was lifted into the excavated reactor building shaft 35 metres below ground. A construction milestone reported by trade press, not a regulatory approval.
Checking notes
World Nuclear News reports that in April 2026 the basemat module, the foundation of the reactor building weighing nearly 953 tonnes, was lifted into the newly excavated reactor building shaft 35 metres below ground. The CNSC had removed the hold point for the reactor building foundation on 30 March 2026.
· Signed
Signed: Kentucky KRS 164.2803: nuclear energy development grant cap #
The session-law PDF prints Signed by Governor April 8, 2026. It does not print an effective date for section 5. No award is named.
· Signed
Signed: Kentucky KRS 164.2805: Nuclear Reactor Site Readiness Pilot Program #
The session-law PDF prints Signed by Governor April 8, 2026. It does not print the 15 July 2026 effective line. That date remains the compiled section.
· Signed
Signed: Kentucky KRS 278.615: nuclear permit and license cost recovery #
The session-law PDF prints Signed by Governor April 8, 2026. It does not print the 15 July 2026 effective line. That date remains the compiled section.
· Signed
Signed: New Jersey P.L. 2026, chapter 9: nuclear facility permit finding #
The official chapter page says Approved April 8, 2026.
· Took effect
Took effect: New Jersey P.L. 2026, chapter 9: nuclear facility permit finding #
Section 2 says the act takes effect immediately.
· Recorded development
DOME test bed complete; Radiant begins its test campaign #
DOE reported on 8 April 2026 that construction of the DOME test bed was complete and that Radiant had started its scheduled year-long test campaign of the Kaleidos unit. Initial startup of the reactor was anticipated in the summer, which is a plan and not a recorded startup.
· Contract
Wylfa programme design contract signed #
Contract initiates site-specific design and planning before a future investment decision.
· Environmental decision recorded
Environmental decision recorded: DOE Idaho categorical exclusion CX-271002 for the Aalo-X critical assembly #
Approved 14 April 2026 under posting DOE-ID-INL-26-013. Covers installation and zero-power operation of the critical assembly at no more than 10 watts thermal. It is an environmental categorical exclusion, not a construction permit or operating licence, and it does not authorize a later power reactor.
· Environmental decision recorded
Environmental decision recorded: DOE Idaho categorical exclusion CX-271007 for the Unity zero-power test #
Approved 15 April 2026 under posting DOE-ID-INL-26-011. Covers a zero-power criticality test bounded at 0 MWth and 0 kWe. It does not authorize the future 1 MWe configuration and is not an operating licence.
· Groundbreaking
Hermes 2 groundbreaking #
Groundbreaking reported for Hermes 2.
· Amended
Amended: Uzbekistan: Law No. ZRU-565 on the Use of Atomic Energy for Peaceful Purposes (2019) #
Law No. ZRU-1140; in force on official publication.
· Construction start
IAEA PRIS records construction start for Darlington SMR1 #
PRIS records physical construction start of Darlington SMR1 on 22 April 2026. This is distinct from the CNSC licence to construct in April 2025 and from the pending operating-licence application.
Announced · Announcement
Radiant Kaleidos Buckley Space Force Base proposal documented #
Company reports Air Force / DIU selection for Buckley. Delivery by 2028 is a target. Separate from the INL demonstration and the unnamed fifteen-base Army fleet.
· Environmental decision recorded
Environmental decision recorded: DOE categorical exclusion CX-271015 for the Ward250 research reactor #
Signed 22 April 2026 under NEPA identification DOE-ID-26-005. Determines that the 250 kWth Ward250 research reactor at USREL fits a categorical exclusion. It states no authorization number and no electrical output, and it does not confirm the company's later electricity claim.
· Construction start
TerraPower announces the official start of construction at Kemmerer Unit 1 #
TerraPower announced on 23 April 2026 the official start of construction on Natrium Kemmerer Unit 1. The same release distinguishes this from earlier non-nuclear site work. Stored electrical and thermal ratings are not changed.
· Recorded development
Stellaria and CEA sign letter of intent on INB Alpha feasibility at Cadarache #
· Recorded development
DOE approves the Ward 250 documented safety analysis #
DOE's Reactor Pilot Program update of July 2026 lists the Valar Atomics preliminary documented safety analysis as approved in February 2026 and the documented safety analysis as approved on 23 April 2026, before zero-power criticality on 18 June 2026. The slides do not reproduce the approval documents.
· Published
Published: Generic environmental impact statement rule for licensing new nuclear reactors #
Final NRC rule effective 26 May 2026 that lets environmental reviews of new reactor applications rely on generic findings. It is not an environmental decision on any project.
· Recorded development
NRC gives notice it will prepare an environmental impact statement for the Belews Creek early site permit #
Published 27 April 2026 at 91 FR 22549: the NRC will prepare an environmental impact statement for the early site permit application and opened a 30-day scoping period, with the U.S. Army Corps of Engineers as a cooperating agency.
· Took effect
Took effect: 10 CFR Part 53: risk-informed, technology-inclusive licensing framework #
The NRC's Part 53 licensing framework took effect on 29 April 2026. It sets how applications may be reviewed; it approves no design, site or reactor.
· Recorded development
DOE approves the Aalo-X documented safety analysis #
DOE's Reactor Pilot Program update of July 2026 lists the Aalo preliminary documented safety analysis as approved on 3 March 2026 and the documented safety analysis as approved on 30 April 2026, before zero-power criticality on 4 July 2026. The slides do not reproduce the approval documents. A safety-analysis approval for a zero-power test does not authorize a later power reactor.
Follow new entries with the RSS feed, or filter every entry on Updates.