Shares of NuScale Power (SMR -1.06%), a developmental-stage maker of small modular reactors, initially popped this morning on an announcement from the White House on expanding nuclear energy production.

While the stock jumped as much as 13% in morning trading, it gave back those gains amid a broader pullback in small-cap stocks in a sign that the boom from Trump's election was fading.

As a result, the stock closed down 1.1% while the Russell 2000 fell 1.8%, with the small-cap index giving back all of yesterday's gains and then some.

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The nuclear climate is improving

The new plan from the White House aims to triple nuclear energy production by 2050, and the plan is supportive of small modular reactors (SMRs), which it said have "strong potential for both grid-based and behind-the-meter resilient electricity."

It also name-checked NuScale's VOYGR power modules, and the plan aims to deploy $900 million for new SMR deployments, some of which could go directly to NuScale.

However, that momentum wasn't enough to carry the stock to a win for the day as broader sentiment headwinds pushed it lower by the end of the session.

NuScale doesn't have material revenue, and the stock has been highly volatile based on sentiment around the nuclear sector.

Is NuScale a buy?

Public policy is likely to have a significant impact on the nuclear sector, and the recent moves from big tech companies to find nuclear sources to power their artificial intelligence data centers are a positive sign as well.

The Trump administration is expected to be favorable to nuclear power, including SMRs like the kind NuScale is focused on building.

Still, investors in NuScale and the broader sector need to be patient, as no SMRs are expected to come online until the end of the decade. For now, expect the volatility to continue as investors place bets on how big of a role nuclear energy and SMRs will play in the future.