Seems to me like they are talking about the Natrium reactors which can run on recycled UNF and can add U238 to breed more Plutonium which makes them a breeder reactor, if they use to Plutonium to achieve this, then they need a small amount HALEU to start the process. but by using pyrotechnology to separate out Plutonium and other actin-ides they also get RepU from the UNF as well, maybe this is why GEH are
also pushing for the BWRX300 as well as the Natrium reactors , the BWRX300 does run of LEU or they could use RepU with poisons removed (silex), which is basically LEU anyway? makes for much better economies I would think, and also helps the US in many other ways, ie reduces waste to around 20% of what it is today, and makes it need only to be stored for around 300 years, it help the US with its problem of where they will get their Uranium and enrichment from for LEU as well as reducing the need for some of it's shortage in conversion and deconversion need as well and allows them to use the Plutonium bundle as well.
https://curtis.house.gov/news/documentsingle.aspx?DocumentID=3281
an advanced nuclear reactor that—mce-anchor
“(I) uses isotopes derived from spent nuclear fuel (as defined in section 2 of the Nuclear Waste Policy Act of 1982 (
42 U.S.C. 10101)) or depleted uranium as fuel for the advanced nuclear reactor; and
“(II) is the first advanced nuclear reactor described in subclause (I) for which the Commission—
(20min delay)