[en] The krypton-85 (Kr-85) released to the reactor building during the accident at TMI-2 must be removed from the reactor building in order to permit greater access to the building than is currently possible. The gases currently in the building emit sufficient radiation (1.2 rem/hr total body, 150 rad/hr skin dose) that occupation of the reactor building is severely limited even with protective clothing. Greater access is likely to be necessary to maintain instrumentation and equipment required to keep the reactor in a safe shutdown condition. In addition greater access would facilitate the gathering of data needed for planning the building decontamination program. An additional consideration is that prolonged enclosure of the Kr-85 within the building greatly increases the risk of its successive uncontrolled releases to the outside environment. The staff's evaluation of alternative methods for removing the krypton shows that each could be implemented with little risk to the health and safety of the public. The reactor building purge system, charcoal adsorption system, gas compression, selective absorption process system, and cryogenic processing system could each be operated to keep levels of airborne radioactive materials to unrestricted areas in compliance with the requirements of 10 CFR Part 20, and the design objectives of Appendix 1 to 10 CFR Part 50 of the Commission's regulations, and with the applicable requirements of 40 CFR Part 190.10