A chemical lonlzatlon mass spectrometrlc method for determining ' OB In enrlched boron was developed and Investigated. Boric acld and methanol were reacted to form volatile methyl borate whlch was directly Introduced Into the Ion source of a quadrupole mass spectrometer. Methyl borate was lonlzed by reactlon with methane and methanol Ions. The 'OB content was determlned from the measured lrB/loB ratio by using the (CH30)3BH+ Ion and a mass spectrometer calibration factor based on the Natlonal Bureau of Standards (NBS) SRM 952 boron Isotope standard. The precision of the chemical lonlzatlon mass spectrometrlc method Is comparable to thermionic emlsslon methods. The relatlve standard devlatlon on repilcate samples dld not exceed 0.009% for the 95% enrlched ' OB samples. The analytical results from 96 enriched boron powder samples were compared by using both thermlonlc emisslon and chemlcal ionization mass spectroscopy. The standard error of the dlfference between palred samples was less than 0.097 across the range of 96 samples. The analysls time Is typlcally less than 10 mln per sample.Boron is used extensively in the nuclear power industry as a neutron absorber in nuclear control rods, nuclear shielding, and neutron detecting devices and as a burnable poison in nuclear fuels. The loB isotope with a natural abundance of 19.8 atom % provides this property because of a relatively high thermal neutron capture cross section (3840 b). The isotopic composition of boron can be a critical factor in the design of nuclear shielding, control systems, and neutron detectors. Therefore, it is essential that the ' OB content in boron used in nuclear facilities be known to a high degree of accuracy.Radioanalytical techniques based on both the nuclear transformation of boron nuclei into activated or metastable nuclei and the measurement of the radioactive decay products have been used to determine either loB or "B. Charged particle reactions have been used successfully to distinguish loB and "B in boron by exploiting the reactions 1°B(d, p)llB and "B(p, a)sBe (1, 2). Olivier (3) described a nuclear microprobe method to determine ' OB and "B simultaneously in steel. The coincident measurement of complementary particles in a nuclear transformation, such as the reactions 1°B(d, p)llB and l'B(d, aIQBe, has improved the analytical precision of radioanalytical techniques significantly (4).Neutron absorption and transmission techniques have been applied successfully toward determining loB in boron (5).Indirect techniques provide extremely sensitive methods for the isotopic analysis of boron (6). With these methods, the total boron content must also be known to determine the llB content by difference and, hence, the isotopic composition. A number of other analytical techniques, such as atomic absorption, emission, and nuclear magnetic resonance specPresent address: Sandia National Laboratories, P.O. Box 5800, Albuquerque, NM 87185. troscopy (7), have been applied on a limited basis to the isotopic analysis of boron.Mass spectrometric te...

No abstract

No abstract