Nuclear Reactor Vessel Head Penetrations
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  • Development of an inspection and testing model for reactor vessel head penetrations
  • Economic decision analysis of inspection, repair, and replacement Structural integrity analysis of cracked Inconel 600 nozzles
  • Weld repair evaluations for weld overlay of CEDM canopy seals

Development of Basic Extended Model for Reactor Vessel Head Penetrations

The objective of this project was to provide the client with an updated inspection timing model for evaluation of the reactor vessel heads. The program utilized specific data to establish and benchmark the extended model. Specific elements of the program objective included:

  • Development of a basic extended model to provide probabilistic results for all CEDM nozzles Revision of the model to allow simulation of operating temperature changes
  • Revision of the model to use updated crack propagation data

Justification for Long-Term Acceptance of CRDM Canopy Seal Weld Repairs
Development of Improved Inspection Model

APTECH and a vendor are in the process of developing a new and improved inspection model for CEDM nozzles. This computer program is written in MS Power Station Fortran with a Windows NT Operating System on a Pentium PC. The program will include a new, revised model of SCC initiation and propagation. Results are benchmarked against one lead plant.

Strategic Decision Model for Inspection, Repair, and Replacement of CEDM Nozzles

Cracking of CEDM nozzle penetrations have caused the French utility, Electricite de France (EDF), to make huge capital expenditures for reactor head replacement. United States utilities with nuclear power plants are aware of EDF's problems and have responded by evaluating the risk of similar cracking of their CEDM nozzles. Subsequently, technologies for inspection, remedial actions, and repair of nozzles with cracks have been developed. However, the costs associated with inspection and repair options are substantial. Thus, it is important that strategies for addressing the CEDM nozzle cracking issue be based on best available information and decision analysis techniques.

The objectives of this project were as follows:

  • Develop an economic decision analysis software tool that will help determine the desired optimal timing of future CEDM inspections, as well as the preferred strategies for correcting CEDM nozzle cracking problemsUse the decision tool, along with the currently available best information on repair costs and crack initiation and growth rates, to determine preferred inspection/repair policies, and provide recommendations to the client based on these results
  • Provide the client with the commercial-grade decision tool, along with a User's Manual and training, so that their staff can use it in the future

 

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