Safeguards Analytical Laboratory
Chemical Analysis Unit - Spent Fuel Laboratory
The main task of the laboratory is the preparation of spent fuel samples prior to their measurement by mass-spectrometry and alpha spectrometry. This preparation involves the redissolution of the dried samples and a chemical separation and purification by extraction chromatographic procedures for eliminating interfering elements like Americium and fission products.
The "Large Size Dried Spikes" (LSD spikes) technique is used for the determination of the elemental assays of uranium and plutonium in solutions of irradiated nuclear fuel (also called "spent-fuel solutions" or "input solutions" of reprocessing plants): a certain and well-defined amount of Plutonium- and Uranium-isotopes (spike) is added to a weighed sample aliquot at the safeguarded facilities under the wittness of an IAEA Safeguards Inspectors. The LSD spike material used at the facility has previously been prepared at characterized at SAL in co-operation with other NWAL's. All chemical preparations and measurements are accompanied by the analysis of control samples and blank control materials in the frame of the laboratory's QC programme.
Beside the routine work on some hundred spent fuel samples a year the laboratory deals also with the chemical preparation of various special samples (e.g. high active waste samples and others).
Additionally the spent fuel laboratory has to carry out various projects of high importance. Some of these are listed as follows:
Development of the procedures
The procedures are constantly improved in order to simplify the handling, to decrease the time consumption for routine samples, to avoid critical chemical reagents and - most essential - to improve the precision and the accuracy of the measurements.
Development of existing automation
The existing robot system for the automated processing of spent fuel samples was implemented in 1991 and has successfully performed more than 2000 sample separations up to now. It needs continuous maintenance, improvement and adaptation of both hard- and software.
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Automated spent fuel separation unit |
Development of a demo robot unit
A new robot system will serve as a demo unit for the Agency's on-site automated sample processing at the reprocessing plant Rokkasho-Mura in Japan, which is presently being under construction. The programming of the various steps and the installation and testing of the robot itself and of all the peripherals is one of the major time consuming projects in the spent fuel area and needs continuos contact with the partners in the Japanese facilities.
Handling of "hot swipes"
In cooperation with SAL's Clean Laboratory Unit, certain parts of the preparation of "hot swipe samples" is done in the spent fuel area. This preparation involves cutting the samples (mainly filter papers), ashing, redissolution and a first separation step to eliminate interfering elements. A special combustion apparatus was developed for the ashing and installed in a fume cupboard. The handling of the "swipes" is performed in special plastic glove bags in a laminar flow clean box.
Resin bead technique
This technique was developed in the early seventies in SAL on the basis of procedures of ORNL (Oak Ridge National Laboratory) and LANL (Los Alamos National Laboratory) as a tool to adsorb nanogram quantities of Uranium and Plutonium from Input solutions on single beads (Ø ca. 0,3 mm) of an ion exchange resin. It is presently being studied and adapted to perform reasonable analyses of low and lowest amounts of Uranium and Plutonium in samples which had - due to several national regulations - to be diluted to an extent where the conventional analytical procedures are very hard to perform (e.g. "high active waste samples").
Studies on separation of Curium, Neptunium and Americium
In addition to the routine measurement of Uranium and Plutonium amounts and isotopic ratios, the quantitative measurement of Am-, Cm- and Np-nuclides in spent fuel and liquid waste samples could provide valuable supplementary information about the irradiated fuel characteristics such as burn-up and decay time since removal from reactor core. Two-step column extraction separation procedures, followed by alpha- and mass spectrometric measurements are presently being studied.
Training of Safeguards Inspectors
this means lectures twice a year on practical aspects of sampling, packing for shipment and chemical procedures of sample preparation for IAEA beginners inspectors.