Radioactive Tracer Technology
Measuring Real-Time Wear in Operating Engines
For 40 years, Southwest Research Institute (SwRI) has used radioactive tracer techniques to make highly accurate and sensitive real-time wear measurements in operating engines. These capabilities are particularly important in light of the harsh operating and environmental conditions imposed on today's high-performance engines, in which performance as well as low emissions levels increasingly depend on close-tolerance operation with minimal wear. Using sophisticated instrumentation, SwRI studies real-time wear, detecting wear and wear rate changes instantly. Advantages of radioactive tracer measurement techniques include:
Two radioactive tracer techniques are typically used to measure internal combustion engine component wear: bulk activation and surface- or thin-layer activation (SLA/TLA). SwRI selects the appropriate method based on specific test objectives, component metallurgy, and configuration or site particulars.
For bulk activation testing, components are irradiated in a conventional nuclear reactor and installed in a test engine. As irradiated particles abrade from the components during engine operation, specific radioisotopes serve as detectable tracers in the lubricant. SwRI measures radiation from these particles using a gamma ray spectrometer; radiation is proportional to the mass of the abraded material in the oil. Multiple isotopes can be measured simultaneously, allowing wear from multiple parts or surfaces to be measured in a single test.
Surface- or Thin-Layer Activation
Using SLA/TLA techniques, components are bombarded with a high-energy beam of charged particles to activate a thin layer of atoms on the component surface. Wear is measured by monitoring a decrease in the component's radioactivity or an increase in the radioactivity of debris collecting in a fluid filter.
The Institute's radioactive tracer techniques provide cost-effective, accurate, real-time data, detecting minute wear changes without disassembly and physical inspection, to study component wear under transient and steady-state conditions.
Past SwRI radioactive tracer measurement projects have included:
This brochure was published in June 1994. For more information about radioactive tracer technology, contact Doug Eberle, Principal Engineer, Engine, Emissions and Vehicle Research Division, Southwest Research Institute, P.O. Drawer 28510, San Antonio, Texas 78228-0510, Phone (210) 522-5260, Fax (210) 522-4581.