The Administrator may authorize the manager of a covered nuclear weapons research, development, testing or production facility to engage in research, development, and demonstration activities with respect to the engineering and manufacturing capabilities at such facility in order to maintain and enhance such capabilities at such facility: Provided, That of the amount allocated to a covered nuclear weapons facility each fiscal year from amounts available to the Department of Energy for such fiscal year for national security programs, not more than an amount equal to 2 percent of such amount may be used for these activities: Provided further, That for purposes of this section, the term "covered nuclear weapons facility" means the following:

(1) The Kansas City Plant, Kansas City, Missouri.

(2) The Y–12 Plant, Oak Ridge, Tennessee.

(3) The Pantex Plant, Amarillo, Texas.

(4) The Savannah River Plant, South Carolina.

(5) The Nevada Test Site.