Neutron flux estimations based on niobium impurities in reactor pressure vessel steel
- Technical Research Centre of Finland, Espoo (Finland). Reactor Lab.
The use of (ppm level) niobium impurities in reactor pressure vessel (RPV) steel for neutron flux estimations based on the reaction {sup 93}Nb (n,n{prime}) {sup 93m}Nb has been reported previously. The method has now been further investigated and refined. Small niobium fractions in RPV steel ({approx} ppm) and plating ({approx} 1%) materials have been separated by ion exchange chromatography in one to three steps. The measured Nb fractions in samples from some four pressure vessel (RPV) base materials were 1 to 3 ppm. The purification of tens of milligrams of RPV material provides sufficient amounts of niobium for mass determination with a highly sensitive (10{sup {minus}5} ppm) Inductively Coupled Plasma Mass Spectrometer (ICP-MS). The {sup 93m}Nb and small remaining {sup 54}Mn activities were measured with a Calibrated Liquid Scintillation Counter (LSC) based on dual label technique and almost 100% efficiency to {sup 93m}Nb. One purification is needed for plating materials ({approx}1% Nb) and two purifications of about one gram of steel with Nb impurities in order to resolve the needed activities ({approx}10 Bq {sup 93m}Nb/{mu}g Nb). The achieved accuracy of the measured specific {sup 93m}Nb activities was about {+-} 3% (1{sigma}) in irradiated RPV plating materials and about {+-} 4% for Nb ppm impurities.
- OSTI ID:
- 55588
- Report Number(s):
- CONF-930809-; ISBN 0-8031-1899-6; TRN: 95:012833
- Resource Relation:
- Conference: 8. ASTM-EURATOM symposium on reactor dosimetry, Vail, CO (United States), 29 Aug - 3 Sep 1993; Other Information: PBD: 1994; Related Information: Is Part Of Reactor dosimetry. ASTM STP 1228; Farrar, H. IV; Lippincott, E.P.; Williams, J.G.; Vehar, D.W. [eds.]; PB: 871 p.
- Country of Publication:
- United States
- Language:
- English
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