Austin-based Aalo Atomics, a startup aiming to mass-manufacture nuclear power plants, is raising $100 million to develop an experimental reactor, a source familiar with the effort tells Axios.

Why it matters: The Department of Energy is considering opening 16 federal sites to data centers with on-site power, offering "fast-track permitting for new energy generation such as nuclear."

Driving the news: Aalo launched the fundraising effort in March and expects to close the Series B round in "mid-2025," the source says.

• The company declined to comment.

How it works: Aalo plans to develop nuclear "pods," each containing five 10-MW reactors powering an electricity-generating turbine to produce 50 MW per pod, the source says, adding:

• "When any one reactor is down for refueling, the others can make up the delta, so you can have power all the time," the source says.

Zoom in: Aalo is prioritizing speed. It's using conventional, lower-enrichment nuclear fuel instead of advanced fuel like HALEU or TRISO, and pursuing its first federal signoffs from the Department of Energy instead of the Nuclear Regulatory Commission.

• DOE approval limits Aalo reactors to federal sites, such as national labs and military installations, but the process has moved more quickly than with the NRC.

The big picture: Nuclear power is back in vogue, as a low-carbon alternative to fossil fuels like coal and natural gas — even though some environmentalists have resisted it over concerns about radioactive meltdowns.

What's next: Aalo plans to begin building its Aalo-X experimental reactor in the next year, as well as pursue NRC licensing. It's eyeing a $200 million Series C in the next one to two years, the source says.

• It expects to bring its first reactor online in 2027.

If you need smart, quick intel on dealmaking in the climate industry for your job, get Axios Pro Deals.

Today, on International Workers' Day, protesters in nearly 1,000 cities across the U.S. are expected to rally against what organizers call the Trump administration's "war on working people."

Why it matters: Protests against the administration have built momentum as President Trump faces sinking approval ratings and Americans increasingly witness the ramifications of his policies.

• Thursday's events will include rallies, marches, town halls and other actions against the "billionaire takeover" of the federal government.

Zoom in: An Austin march, organized in part by the 50501 movement, is scheduled for 5pm at the Capitol, with other May Day demonstrations scheduled for Dripping Springs and Lockhart.

• Meanwhile, organizers are gathering to protest at 5pm outside the University of Texas Tower to demonstrate against the revoking of international student visas.

The other side: Trump on Tuesday marked the first 100 days of this stint in the White House as "the most successful ... of any administration in the history of our country."

Go deeper

✋ Gov. Greg Abbott has admonished the city of San Marcos over a proposed resolution calling for a ceasefire in the Israeli-Palestinian conflict. (Fox 7 Austin)

🧳 The city of Austin is reassigning 21 health workers in the Austin Public Health immunizations unit after the agency lost $15 million to federal grant cuts. (CBS Austin)

💰 Austin will need nearly $101 million next year to adequately fund emergency shelters and support services for the city's homeless population, per the city's homeless strategy officer. (KUT)

📱 The Texas House passed a bill that would prohibit minors from creating social media accounts and require age verification for new users. The legislation next goes to the Senate. (Texas Tribune)

Here's what's in store for the weekend.

Friday

🎨 Find Mother's Day gifts and more at Blue Genie Art Bazaar's May Market, which kicks off Friday at 10am with handmade creations from nearly 200 regional artists and artisans.

• Open every Friday through Sunday, 10am-8pm until June 1. Free.

Saturday

💭 Catch a Q&A with Alana Stewart, the actress, author and talkshow host, about her longtime friendship with Farrah Fawcett at the Umlauf Sculpture Garden and Museum beginning at 6:30pm. Free.

🛒 Head to H-E-B's SoCo Social, 10am-2pm, with brunch bites and giveaways. Free.

Sunday

☕️ Enjoy free food, drinks and raffle opportunities at Café Largesse's grand opening celebration, noon-3pm.

📖 Take ballroom dance lessons, have high tea and listen to a special storytime at Book People's Jane Austen Day, 9am-9pm. Free.

💫 Get free entry to the Bullock Museum during Star Wars Day, 10am-2pm with a space-themed storytime and live music.

Fiesta San Antonio continues this weekend, with parties, music and culture across the city.

Why it matters: It's an easy trip from Austin, and Fiesta raises millions of dollars for local nonprofits and brings thousands of attendees to the core of the city.

How it works: Fiesta is a giant umbrella with more than 100 official events — free and ticketed.

• And there are plenty of themed, offshoot events happening at bars and restaurants.

What to try: A Night in Old San Antonio (NIOSA), heralded as a hub for eats, continues through Friday.

• Plus, there's Friday's Battle of Flowers Parade and Saturday's Fiesta Flambeau Parade. See the full calendar here.

Dig deeper: Our friends at Axios San Antonio are hard at work covering the 11-day party.