Civilian reactors in Tennessee notionally will sharply increase their output of tritium for U.S. nuclear weapons by the fall of 2024 to help the National Nuclear Security Administration (NNSA) produce its desired 2,800 grams of tritium annually during the government fiscal year that begins around that time, officials said Wednesday morning.

If the Nuclear Regulatory Commission grants the Tennessee Valley Authority’s (TVA) planned license amendment, the authority’s two Watts Bar reactors will each be allowed to irradiate some 2,500 tritium producing burnable absorber rods per generating cycle, with Unit 1 starting in fall 2024 and Unit 2 beginning in spring 2025.

That is according to Charlie Davis, a project manager at TVA, who spoke in a public meeting about the plans on Wednesday. For Unit 1, the increased tritium rod loading would begin with the reactor’s 19th generating cycle. For Unit 2, it would begin with the 6th.

Compared with the most recent generating cycles for the reactors, which make tritium for nukes while producing electricity for the public, that would mark an increase of not quite 1,000 rods for Watts Bar 1, which has irradiated tritium since nearly 2003, and a nearly five-fold increase for Unit 2, which only started producing tritium in late 2020 and was loaded up with only 544 of a planned 1,000 or so rods.

The Department of Energy’s semiautonomous NNSA has said it needs the Watts Bar reactors each to produce about 2,800 grams of tritium per cycle starting in fiscal year 2025, which begins Oct. 1.

The Pacific Northwest National Laboratory, which designed the tritium producing burnable absorber rods, thought the reactors might need only 1,500 or so rods per cycle to meeting the NNSA’s goals.

During Wednesday’s meeting, Russel Wells, TVA’s licensing project manager, said the authority planned to host a status update about its license amendment request with NRC in May or June.

The Pacific Northwest National Laboratory designs tritium producing burnable absorber rods, which Westinghouse [WX] manufactures in South Carolina. The TVA irradiates the rods in its civilian power reactors, which produces tritium that the NNSA then harvests at DoE’s Savannah River Site near Aiken, S.C. Eventually, the tritium finds its way into reservoirs that are installed in nuclear weapons. The radioactive hydrogen isotope greatly increases the efficiency and destructive power of modern thermonuclear weapons.