Nuclear Power Reactors

Entropy Limited has worked extensively on nuclear reactor performance and safety. The work involves loss of coolant accidents, pump and valve failures, fuel rods, and long term underground storage of hazardous materials.

Nuclear Fuel Performance

Working in cooperation with Stanford University's Department of Materials Science, Science Applications, Inc., Failure Analysis Associates and the University of Manchester (U.K.)'s Department of Materials, Entropy Limited designed and built the SPEAR system for the Electric Power Research Institute (EPRI) to simulate stress-corrosion cracking and leaking of fuel canisters in commercial power reactors under varying operational and environmental conditions. This system enabled electric power utilities, for the first time, to make accurate before-the-fact predictions of failure rates due to stress-corrosion cracking of fuel rod cladding in nuclear reactors.  The SPEAR models were designed to simulate both thermo-mechanical behavior of the fuel and cracking of the cladding. Entropy Limited developed mechanistic algorithms for transient heat flow, mechanical stress-strain effects, corrosion, and crack initiation and propagation.   Laboratory experiments were performed at Stanford University to provide physical parameters.  The SPEAR software was prepared by EL in IBM and CDC versions, with associated User's Manuals and training sessions.  Uses of the SPEAR system include training in failure avoidance operation, fuel cycle management, and fuel design evaluation. Over 3400 assembly cycles were analyzed for fuel reliability and 139 fuel rods were analyzed for fission gas release to estimate risk of containment rupture and fission gas leakage under real-time operating conditions to enable low risk power cycle management. The reactors included:

Reactor Fuel Reliability

In cooperation with the MIT Nuclear Engineering Department, Entropy Limited analyzed fuel failure and reliability of Carolina Power & Light Company's Brunswick-2 reactor. (For the Electric Power Research Institute.)

Fission Gas Release

For the Halden Reactor Project in Norway, Entropy Limited processed test reactor data in search of patterns in fission gas release. For the Electric Power Research Institute a model that predicts fission gas release was developed.

Nuclear Safety

In cooperation with Battelle Northwest Laboratory, Entropy Limited analyzed all available Loss of Coolant Accidents (LOCA) data for patterns related to nuclear safety. The analysis of this catastrophic worst case scenario uncovered a high dependence on experiment dependent factors, resulting in a licensing requirement of further testing under more carefully controlled protocols. (For the U.S. Nuclear Regulatory Commission.)

Very Long Term Underground Disposal of Nuclear Waste

For the Office of Nuclear Waste Isolation of the Battelle Project Management Division (BPMD), Entropy Limited worked in cooperation with Massachusetts Institute of Technology (MIT) providing consultation and computational support in the design of high level radioactive waste containers. Key to the project was assessment of corrosion rates and leakage risks for thick-walled steel containment tanks stored in deep salt mines, with the objective of determining whether or not the design meets requirements for long term (many hundreds of years) leak-free storage.  Also studied was the migration/diffusion rate in the event of leakage.

 

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