Energy and Water Development Appropriations: Nuclear Weapons Activities [Updated January 6, 2020] [open pdf - 1MB]
From the Summary: "NNSA [National Nuclear Security Administration] operates three programs: Defense Nuclear Nonproliferation, [...] Naval Reactors, [...] and Weapons Activities. The last is the subject of this report. The Weapons Activities account supports programs that maintain U.S. nuclear missile warheads and gravity bombs and the infrastructure programs that support that mission. Specifically, according to DOE's [Department of Energy] budget documentation, these programs 'support the maintenance and refurbishment of nuclear weapons to continue sustained confidence in their safety, reliability, and performance; continued investment in scientific, engineering, and manufacturing capabilities to enable certification of the enduring nuclear weapons stockpile; and manufacture of nuclear weapons components.'"
CRS Report for Congress, R44442
Congressional Research Service: https://crsreports.congress.gov/