50 USC 2529 - Requirements for specific request for new or modified nuclear weapons

(a) Requirement for request for funds for development 

(1) In any fiscal year after fiscal year 2002 in which the Secretary of Energy plans to carry out activities described in paragraph (2) relating to the development of a new nuclear weapon or modified nuclear weapon, the Secretary shall specifically request funds for such activities in the budget of the President for that fiscal year under section 1105 (a) of title 31.
(2) The activities described in this paragraph are as follows:
(A) The conduct, or provision for conduct, of research and development which could lead to the production of a new nuclear weapon by the United States.
(B) The conduct, or provision for conduct, of engineering or manufacturing to carry out the production of a new nuclear weapon by the United States.
(C) The conduct, or provision for conduct, of research and development which could lead to the production of a modified nuclear weapon by the United States.
(D) The conduct, or provision for conduct, of engineering or manufacturing to carry out the production of a modified nuclear weapon by the United States.
(b) Budget request format 
The Secretary shall include in a request for funds under subsection (a) the following:
(1) In the case of funds for activities described in subparagraph (A) or (C) of subsection (a)(2), a single dedicated line item for all such activities for new nuclear weapons or modified nuclear weapons that are in phase 1, 2, or 2A or phase 6.1, 6.2, or 6.2A (as the case may be), or any concept work prior to phase 1 or 6.1 (as the case may be), of the nuclear weapons acquisition process.
(2) In the case of funds for activities described in subparagraph (B) or (D) of subsection (a)(2), a dedicated line item for each such activity for a new nuclear weapon or modified nuclear weapon that is in phase 3 or higher or phase 6.3 or higher (as the case may be) of the nuclear weapons acquisition process.
(c) Exception 
Subsection (a) shall not apply to funds for purposes of conducting, or providing for the conduct of, research and development, or manufacturing and engineering, determined by the Secretary to be necessary
(1) for the nuclear weapons life extension program;
(2) to modify an existing nuclear weapon solely to address safety or reliability concerns; or
(3) to address proliferation concerns.
(d) Definitions 
In this section:
(1) The term life extension program means the program to repair or replace non-nuclear components, or to modify the pit or canned subassembly, of nuclear weapons that are in the nuclear weapons stockpile on December 2, 2002, in order to assure that such nuclear weapons retain the ability to meet the military requirements applicable to such nuclear weapons when first placed in the nuclear weapons stockpile.
(2) The term modified nuclear weapon means a nuclear weapon that contains a pit or canned subassembly, either of which
(A) is in the nuclear weapons stockpile as of December 2, 2002; and
(B) is being modified in order to meet a military requirement that is other than the military requirements applicable to such nuclear weapon when first placed in the nuclear weapons stockpile.
(3) The term new nuclear weapon means a nuclear weapon that contains a pit or canned subassembly, either of which is neither
(A) in the nuclear weapons stockpile on December 2, 2002; nor
(B) in production as of that date.