Patent and Publications by N. J. McCormick
University of Washington, Seattle, WA 98195-2600
As originally developed, gas tagging consists of the addition to the fuel pins of a nuclear reactor small amounts of gas, with a unique isotopic composition for each assembly. When an assembly developed a leak and released its fission gas and tag gas contained under pressure into the sodium coolant, a mass spectrometric analysis of the reactor cover gas was used to identify which of the many assemblies had failed. During the 1970s this technique was developed and very successfully used during the operation of the Fast Flux Test Facility (FFTF) operated by the Hanford Engineering Development Laboratory (HEDL) in Richland, Washington.
The gas tagging technique developed at HEDL used isotopes of the benign, inert gases krypton and xenon. The unique tag gas compositions were achieved with preferential enrichment of the isotopes of 78Kr, 80Kr, 82Kr, 126Xe, and 129Xe. The three ratios 78Kr/80Kr, 82Kr/80Kr, and 126Xe/129Xe were used. The technique also could also be applied for applications other than nuclear reactors like FFTF. However, the FFTF was a liquid sodium cooled reactor with an inert gas, helium, used as a cover gas to prevent the contact of the sodium with air (that, in inappropriate mixtures, is prone to ignite). The system was designed to work only when the radioactivity from the fission gas was detected in the cover gas. To use the technique in other applications, another mechanism would be needed to alert an operator to perform a mass spectrometric analysis to identify the source of the tag gas release into a cover gas.Method of Preparing Gas Tags for Identification of Single and Multiple Failures of Nuclear Reactor Fuel Assemblies. U.S. Patent No. 3,959,069, May 25, 1976. (This was patented in five countries.)
Gas Tag Identification of Failed Fuel--I. Synergistic Use of Inert Gases (with R. E. Schenter). Nuclear Technology, 24, 149-155 (1974).
Gas Tag Identification of Failed Fuel--II. Resolution Between Single and Multiple Failures. Nuclear Technology, 24, 156-167 (1974).
A Computational Technique to Assess Procedures for Failed Fuel Identification. Nuclear Science and Engineering, 56, 7-15 (1975).
Gas Tag Identification of Failed Reactor Assemblies--III. Tag Ratios for the Fast Flux Test Facility Cores I-IV (with R. E. Schenter and R. P. Omberg). Nuclear Technology, 29, 200-208 (1976).
Gas Tag Identification of Failed Reactor Assemblies--IV. Analysis Methods (with J. A. Figg, R. E. Schenter, and F. Schmittroth). Nuclear Technology, 50, 16-24 (1980).
A Computational Technique for Assessing Procedures to Locate Failed Fuel. Transactions of the American Nuclear Society, 16, 140-141 (1973).
Gas Tagging Designs for Fuel Failure Identification. Transactions of the American Nuclear Society, 18, 270-271 (1974).
Gas Tag Design for Cores I-IV of FFTF (with R.E. Schenter and R. P. Omberg). Transactions of the American Nuclear Society, 21, 376-377 (1975).
Design of Gas Tags for CRBRP (with R. E. Schenter). Transactions of the American Nuclear Society, 22, 520 (1975).
A Preliminary Benefit-Cost Analysis for Gas-Tagging of the CRBRP. Transactions of the American Nuclear Society, 23, 471-472 (1976).
Probabilistic Identification of Failed Core Assemblies from Gas Tag Releases (with J. F. DeClue and F. Schmittroth). Transactions of the American Nuclear Society, 27, 686-687 (1977).
Gas Tagging for Identification of Failed Rods in LWR Assemblies. Transactions of the American Nuclear Society, 32, 590-591 (1979).
Gas Tag Location Systems for FFTF and CRBRP Failed Assemblies (by J. A. Figg, R. E. Schenter, F. Schmittroth, J. F. DeClue and F. E. Holt) Hanford Engineering Development Laboratory Report HEDL-TME 78-14 (1978).