The process of elemental analysis is essential to supporting the analytical laboratory’s mission. The analytical equipment at the NMCD can provide detailed elemental analysis through the use of x-ray diffraction, x-ray fluorimetry, mass spectrometry, and carbon & oxygen/nitrogen analysis. The elemental analysis instrumentation include:
- Thermal Ionization Mass Spectrometry (TIMS)
- Inductively Coupled Plasma-Mass Spectrometry (ICP-MS)
- Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES)
- X-Ray Diffraction (XRD) & Micro X-Ray Diffraction (Micro XRD)
- X-Ray Fluorimetry (XRF)
- Carbon Analyzer
- Nitrogen/Oxygen Analyzer
The elemental analysis equipment at the NMCD can detect trace elements in the ranges of parts per million (ppm), parts per billion (ppb), and parts per trillion (ppt), depending on the sample being tested.
Inductively Coupled Plasma Mass Spectrometry and Atomic Emission Spectrometry
The VG Elemental (now Thermo Elemental) Plasma Quad 3-Nuclide (PQ3) inductively coupled plasma mass spectrometer is used to measure uranium, neptunium, americium, fission products, and trace metals. The instrument varies from typical commercial ICP-MS instruments in that it is specifically designed to incorporate a one half-glovebox. This glovebox is needed to facilitate the analysis of irradiated samples. The glovebox limits exposure to personnel, as well as minimizes the chances of contamination emanating from the samples to contaminate the personnel/laboratory. In addition, a CETAC autosampler is used to facilitate the analysis of samples.
The ICP-MS instrument at the NMCD can detect trace elements in the ranges of parts per million (ppm), parts per billion (ppb), and parts per trillion (ppt), depending on the sample being analyzed. Also, it has significantly higher throughput when compared to TIMS. But TIMS has higher precision and accuracy.
Thermal Ionization Mass Spectrometry (TIMS)
The Finnigan Triton thermal ionization mass spectrometer is used for high precision total and isotopic uranium and plutonium analysis. This instrument has 9 Faraday cups whose positions are automatically set. Each Faraday cup collector can measure signals as large as 50 volts. In this setup sample is deposited on a rhenium ribbon which is placed in a twenty one position turret and inserted into the mass spectrometer ion source. An electric current heats the rhenium ribbon to high temperature, which causes the sample to ionize. The ions are separated from one another based on their mass-to-charge ratio by a magnetic field.
The concentrations of uranium and plutonium isotopes are determined using isotope dilution mass spectrometry technique. Precise known amount of enriched Pu-244 is used as spike. Mass fractionation effects for uranium and plutonium isotopes are corrected using Certified Reference Materials purchased from New Brunswick Laboratory.
TIMS is used for nuclear material accountability measurements for the INL Safeguard program. Other uses include age dating and burnup studies. Most recently, TIMS was used for measuring Boron isotopes in irradiated control rods.