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Radiochemical Processing Laboratory

Helium Gas Measurements

Brian Oliver (foreground) and Larry Greenwood check over the Lab's new helium monitoring system.
Section of helium spectrometer system. (Enlarge image)

Helium is generated in reactor materials by nuclear reactions which produce alpha particles. Unlike hydrogen, which often diffuses through materials, helium accumulates at grain boundaries and voids causing materials to swell significantly. Helium may accelerate radiation damage effects such as embrittlement and is known to inhibit or prevent welding to repair cracks in reactor materials. PNNL has a unique helium mass spectrometry system that provides highly accurate, sensitive measurements in radioactive materials.

Helium Measurement Services

A unique high-sensitivity isotope-dilution gas mass spectrometer system for measurement of extremely low concentrations of helium in very small solid materials and gases is operational at PNNL. Originally developed at Rockwell International, and transferred to PNNL in 1996, this new facility is capable of providing neutron dosimetry and helium analysis services for utilities and research laboratories in the United States, Europe, Japan, and elsewhere. The capabilities of the system include:

  • Analysis of both normal and radioactive samples.
  • A dynamic range of helium measurement from percent levels to parts-per-trillion (10-12 atom fraction), with an absolute accuracy of 1% or better.
  • Analysis of samples ranging in mass from a few micrograms to several grams.
  • Measurement of total helium content (by vaporization) or helium release as a function of time or temperature (for diffusion and/or kinetics measurements).
  • Measurement of both 4He and 3He (from tritium decay) separately or simultaneously.
  • Determination of low tritium levels by measurement of the accumulation of the decay product 3He.
  • Determination of ppm, and below, boron levels through supplemental thermal neutron irradiation followed by helium analysis (boron is a major contributor to helium generation in reactor materials).
  • Helium determinations in geologic and space materials.

Point of Contact:
Ingrid Burgeson, Nuclear Chemistry & Engineering Team
Phone: (509) 375-5387

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