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Alternate Decay Heat Removal (ADHR) System

MLEA Inc. recently designed and supported the installation of an Alternate Decay Heat Removal (ADHR) system at the Cooper Nuclear Station in Brownville, Nebraska. The ADHR system more than doubled the heat removal capacity of the existing spent fuel cooling at Cooper and provides additional capacity for (1) early fuel movement during outages (2) early outage maintenance of normal cooling systems and (3) back-up capacity for unexpected events or postulated accidents.

The ADHR system alone, with no help from the current Spent Fuel Pool (SFP) cooling system or the Residual Heat Removal (i.e. shutdown cooling), can remove decay heat from an entire spent reactor core at 10 days after plant shutdown. Unique ADHR design features include back-up 1E power supplies and provisions for connection of the cooling source to portable skids outside the reactor building, if needed.

The Cooper ADHR system was the largest nuclear plant modification project ever undertaken by MLEA Inc. MLEA combined its substantial and wide-ranging nuclear consulting expertise with the hands-on design experience obtained through years of engineering, design and construction of industrial gas plants and specialty gas facilities.

These separate technical capabilities merged smoothly to create a functioning nuclear-plant design modification team that took its conceptual design to a complete modification package in less than twelve months, with approval by the plant safety-committee four months later and start-up five months after that. The system, which was initially installed to support decontamination activities during a refueling outage, met design objectives by maintaining spent fuel pool and refueling cavity temperatures below 110°F with shutdown cooling secured for decontamination (temperature actually peaked at 106°F).

MLEA Inc. has a long record of spent fuel pool analyses and improvements. MLEA supported an alternate decay heat removal modification at the James A. Fitzpatrick Plant as early as the late 1980s. In addition, we provide technical support to outage decay-heat management activities, including heat-up curves and contingency event curves, for a number of nuclear clients starting in the early 1990s.

MLEA Inc. decay heat management calculations have been automated to the point where curves can be revised and reissued as outage conditions and equipment or system configurations change during refueling. Finally, MLEA personnel have conducted numerous spent fuel pool technical evaluations and provided recommendations for improvements. These evaluations have included upgrading the Salem Generating Station pools to preclude boiling events, the above ADHR modifications at Cooper and a similar improvement study for the Columbia Station. [Previous Page]