<div id="readability-page-1"><div><p><span>(Platts)--04Dec2025/149 pm EST/1849 GMT     **Unit operating at 35% of capacity     **Crews investigating cause     **To test equipment before restoring power     Constellation Energy's 1,207-MW LaSalle-1 nuclear unit in Marseilles, Illinois, was operating at reduced output Dec. 4, according to a company spokesperson.     Operators reduced power beginning the afternoon of Dec. 3 &#34;after the trip of a reactor recirculation pump,&#34; Brett Nauman said Dec. 4.     LaSalle-1 was operating at 35% of capacity early Dec. 4, down from 98% the previous day, according to the US Nuclear Regulatory Commission's reactor status reports.     &#34;Technical crews are investigating the cause and will test and inspect all associated equipment before returning the unit to full power,&#34; Nauman said.     — Steven Dolley, steven.dolley@spglobal.com-- Edited by Giselle Rodriguez, newsdesk@spglobal.com--Platts Electricity Alert--</span></p></div></div>

<p>Constellation Energy's LaSalle-1 nuclear unit in Illinois reduced output to 35% after a reactor recirculation pump trip. Crews are investigating the cause and will test equipment before restoring full power.</p>

PLATTS: 100--Constellation nuclear unit in Illinois reduces output after pump trip