US HB4236

Authorizes the Department of Energy to dispose of foreign-origin americium-241 (Am-241) sealed sources at the Waste Isolation Pilot Plant (WIPP) in New Mexico, which currently only accepts U.S.-origin materials

Classifies foreign-origin proliferation-attractive fissile and radiological materials containing transuranic elements as "waste materials generated by atomic energy defense activities," making them eligible for WIPP disposal

Addresses nuclear nonproliferation concerns by establishing a disposal pathway for Russian-origin Am-241 sources that could otherwise be used in radiological dispersal devices ("dirty bombs")

Expected disposal volume is minimal, estimated at 1-2 shipments per year with negligible impact on WIPP operations

Amends Section 3132(c)(1) of the Ronald W. Reagan National Defense Authorization Act for Fiscal Year 2005 (50 U.S.C. 2569(c)(1)) to enable the National Nuclear Security Administration to accelerate removal of disused sealed sources from domestic and international facilities