Case Histories

•The TVA Story
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TVA-NUCLEAR
Tennessee Valley Authority-A Key SCI Client For over 35 years

TVA in Tennessee supplies electrical power to seven major states. They produce Hydro- Power, Fossil power, and NUCLEAR power.

In the 1960’s, Nuclear Energy became a new and major source of creating electrical power. It was more efficient, less costly to produce, and is cleaner than fossil or hydro energy. However, being a relatively new player in the market, there was much to be learned and understood. Nuclear Energy is created when atoms are split. Harnessing as well as overall management of this power source, presented many new and difficult issues. There was much to learn, gain, and regulate.

The NRC (Nuclear Regulatory Commission) established strict guidelines and standards for OEM manufacturers to meet. There are seismic testing and aging analysis (1E) criteria the product must pass before it can be installed in a Nuclear Site. SAFETY is the premier concern in everything connected with Nuclear Energy. Each assembly and every component has to meet this criterion. The paper trail (traceability) of every nut, bolt, wire, and electrical component must pass the standards set by the NRC.

At one time, TVA had the most ambitious Nuclear Power program in the United States. Equipment for 17 Power reactors would be needed from SCI. However, as the nuclear power projections flattened in the 70’s (due to spiraling costs, longer construction times, licensing procedures and increased complex regulatory requirements) the need for our UPS equipment was recalculated. TVA place an order for Watts Bar (SCI order 6737) for eight 20KVA systems in 1974. This equipment shipped in 1975. Four of these units were diverted to the Sequoyah #1 plant. Sequoyah then ordered eight additional systems in 1979 (SCI order 13674) and sent four of them back to Watts Bar for the ones they obtained from their initial order! Today, TVA has six operational Nuclear sites that have SCI equipment: Browns Ferry 1,2&3, Sequoyah 1&2 and Watts Bar 1.

Recently, SCI replaced units at Sequoyah 1& 2. The original equipment used a constant voltage transformer (CVT)originally manufactured by GE. This transformer has been obsolete since the early 80’s and essentially had an overall design life of 20-25 years. Since the late ‘70s SCI has been manufacturing our own CVTs, which are electrically a form, fit and function replacement for the GE transformers. However, given the seismic requirements for this Nuclear 1E rated equipment, replacing the GE CVTs in the field is not economically feasible because they may not be mechanical form, fit and function replacements (i.e. they may have a different footprint and weight).

The new units have Static Switches added, and the new systems meet the EMI/RFI (EPRI 102323R1) criteria recently adopted by Nuclear Industry. These systems also meet the 40-year design life (with scheduled replacement of key components) criteria.

TVA’s Nuclear Corporate office is located in downtown Chattanooga, TN. Even when visiting there, strict security is observed. Much like airport security, you are cleared through a detector. Then you must check in at a security point and wait for the person you came to visit. Once your escort has greeted you, you can proceed with your business. You are with a TVA escort throughout your entire visit. (even to the ladies’ or mens’ facilities-Now that is security!!!)