The continued safe and reliable operation of the ATR is critical to the Department of Energy (DOE) Office of Nuclear Energy (NE) mission. While ATR is safely fulfilling current mission requirements, a variety of aging and obsolescence issues challenge ATR engineering and maintenance personnel’s capability to sustain ATR over the long term. First documented in a series of independent assessments, beginning with an OA Environmental Safety and Health Assessment conducted in 2003, the issues were validated in a detailed Material Condition Assessment (MCA) conducted as a part of the ATR Life Extension Program in 2007.Accordingly, near term replacement of aging and obsolescent original ATR equipment has become important to ensure ATR capability in support of NE’s long term national missions. To that end, a mission needs statement has been prepared for a non-major system acquisition which is comprised of three interdependent subprojects. The first project will replace the existent diesel-electrical bus (E-3), switchgear, and the 50-year-old obsolescent marine diesels with commercial power that is backed with safety related emergency diesel generators, switchgear, and uninterruptible power supply (UPS). The second project, the subject of this major modification determination, will replace the four, obsolete, original primary coolant pumps (PCPs) and motors. Completion of this and the two other age-related projects (replacement of the ATR diesel bus [E-3] and switchgear and replacement of the existent emergency firewater injection system) will resolve major age-related operational issues plus make a significant contribution in sustaining the ATR safety and reliability profile. The major modification criteria evaluation of the project pre-conceptual design identified several issues that lead to the conclusion that the project is a major modification: 1. Evaluation Criteria #3 (Change of existing process). The proposed strategy for equipping the replacement PCPs with VFDs and having the PCPs also function as ECPs will require significant safety basis changes requiring DOE approval. 2. Evaluation Criteria #4 (Use of new technology). The use of VFD and VFD “pump catcher” technology for the PCPs is not currently in use and has not been previously formally reviewed/approved by DOE for ATR. It is noted that VFD technology has several decades of commercial use and experience. However, the ATR probabilistic risk assessment will have to be updated, reflecting the changes for supplying ECP flows including VFD reliability, to confirm that the proposed activity maintains or reduces the CDF for the ATR. 3. Evaluation Criteria #5 (Create the need for new or revised safety SSCs). It is expected that the proposed activity will result in a revised list of safety-related SSCs. Specifically, as currently proposed, the existing ECPs will be deleted from the list. The PCPs and their associated components, picking up the ECP function, will be classified as safety-related active Seismic Category I.
