MPR's Nuclear Experience

MPR Associates has undertaken numerous engineering tasks related to main coolant pumps manufactured by all three of the principal suppliers in the United States since the early 1970s. MPR's experience includes structural and rotor dynamic analysis, failure analysis and mechanical design of pump components. Much of this work has been directed toward improving the reliability of main coolant pump shaft seals. This work included an in-depth examination of quality control, maintenance practices and tooling; operating practices; and the development and testing of improved seal designs. These efforts resulted in improvements to maintenance and installation procedures, changes in plant operating practices, and a significant increase in seal performance and reliability.

MPR played a major role in the development of design requirements for main coolant pumps and shaft seals for next-generation Light Water Reactors. The objective of this industry-wide project is to define electric utility industry needs for improved reliability, operability, and maintainability in any future LWR plant designs.

Main Coolant Pumps Project Summary
Examples of MPR tasks include:

• Analyzed the causes for, and consequences of, multiple cracks, found in the shafts of PWR main coolant pumps. Developed and applied fracture mechanics techniques not previously used in such applications.

• Reviewed shaft-seal operations and maintenance to improve the operating reliability of the seals.

• Provided technical assistance to a utility member of a joint effort to develop a new shaft seal design for main coolant pumps used in BWRs. This effort resulted in the successful development and implementation of a new, long-life seal design.

• Provided technical direction of a project to improve the reliability of shaft seals used in reactor-recirculation pumps in BWRs. This project implemented improved seal refurbishment, installation, and operating procedures; tested the original seal design under laboratory conditions to confirm the reasons for its degradation; and developed and tested replacement seal designs. The seal design developed is now successfully used in pumps in two BWRs.

• Provided technical direction of a project to analyze and test a shaft-seal design used in BWR reactor-recirculation pumps to determine its leakage characteristics under loss-of-cooling conditions representative of a station blackout event.

• Provided technical direction of a task-force evaluating seal reliability issues related to extension of the length of the refueling interval for a multiunit BWR plant.

• Conducted an independent investigation of the cause of failure of an RCP shaft. This effort included direction of metallurgical examinations, preparation of structural and rotor dynamic analyses, and review of operating and manufacturing history.

• Directed investigations into the failure of internal bolting in several main coolant pump designs. Developed improvements to materials and designs of the bolting as well as improvements to the methods of installation and locking of the bolts.

• Developed a precision hoist designed specifically for installing and removing RCP seal cartridges.

• Provided technical review of the procurement, design, manufacture, and testing of RCPs for PV-IR power plants.

• Analyzed the cover-to-casing joint design for an existing RCP design. Developed a joint design with improved capability to handle thermal upsets.

• Analyzed the fatigue usage of RCP pump covers due to stresess caused by RCP heatup and cool down. Evaluated the expected growth of pre-existing cracks due to these cycles.

• Evaluated the structural significance of inclusions found during volumetric inspection of RCP casings.

Contact

The following pages provide insight on our experience in a few of MPR's nuclear D&D projects:

• Three Mile Island Unit 2 Reactor
  
• Technical Assistance for PUREX
  
• Technical Oversight at Fort St. Vrain
  
• Radioactive Waste Handling
  
• Spent Nuclear Fuel Handling Shipping and Storage
  
• Radiation Shielding Design
  
• Chernobyl
  
• Hanford Spent Nuclear Fuel Project