[en] Three calorimeters were developed for the IAEA: a small-sample portable calorimeter, a bulk calorimeter for up to 2 kg Pu in cans and capable of measuring up to 25 watts, and a calorimeter for 4-m long LWR Pu-recycle fuel roads. Design parameters and performance capability are given, and the instruments are compared with those developed for NRC

[en] An analysis of the early portion of the power-history data collected with both of the IAEA's air-cooled bulk calorimeters has demonstrated that such calorimeters can measure the power from preheated containers of plutonium oxide with an accuracy of 2 to 5% in 15 to 30 minutes. Material accountancy at plutonium facilities has a need for such a capability for measurement of Pu scrap. Also, the International Atomic Energy Agency (IAEA) could use just two calorimeters and a gamma-ray assay system for reliable variables and attributes measurements of plutonium mass during a two-day physical-inventory verification (PIV) at a mixed-oxide (MOX) fuel-fabrication facility. The assay results would be free of the concerns about sample moisture, impurities, and geometry that previously have limited the accuracy of assays based on neutron measurements

[en] A nondestructive autoradiographic technique is described which can provide a verification of the piece count and the plutonium content of plutonium-containing fuel elements. This technique uses the spontaneously emitted gamma rays from plutonium to form images of fuel elements on photographic film. Autoradiography has the advantage of providing an inventory verification without the opening of containers or the handling of fuel elements. Missing fuel elements, substitution of nonradioactive material, and substitution of elements of different size are detectable. Results are presented for fuel elements in various storage configurations and for fuel elements contained in a fast critical assembly

[en] Described are autoradiographic techniques which can verify the number and SNM content of plutonium- and uranium-containing fuel elements. These techniques are applied to fast critical assembly fuel and to low-enriched uranium in LWR fuel assemblies. Autoradiographic images are formed by the spontaneously emitted X and gamma rays from the fuel elements striking X-ray film in contact with the fuel elements or their containers. Autoradiography allows a large number of items to be examined in a minimum inspection time and with minimum facility impact. Results are presented for fast critical assembly fuel in a variety of storage modes as well as in fast critical assemblies themselves. Results are also presented for low-enriched uranium rods in unirradiated LWR fuel assemblies. In all cases, missing fuel elements or substitution of elements containing inert material or depleted uranium were detected

[en] A nondestructive autoradiographic method is described which can provide a verification that rods in the interior of unirradiated LWR fuel assemblies contain low-enriched uranium. Sufficient absorber must be used to reduce contributions to image density by beta radiation from ²³⁸U daughters. When appropriate absorbers are used, the density of the image of a uranium-containing fuel rod is proportional to the ²³⁵U enrichment in that rod. Exposure times as short as 1.5 hours can be achieved by using fast film and intensifying screens. Methods are discussed for reducing contributions to the image density of any single rod from radiation produced by all other rods in the assembly. The technique is useful for detecting missing rods, dummy rods, and rods containing depleted uranium. These defects can be detected by visual inspection of the autoradiographs. In its present state of development, the technique is not sensitive enough to reliably detect the difference between the various ²³⁵U enrichments encountered in current BWR fuel assemblies. Results are presented for field tests of the technique at BWR and PWR facilities

[en] The Bulk-Assay Calorimeter described in ANL-NDA-9/ISPO-14 was field tested at the Belgonucleaire mixed-oxide fuel fabrication plant at Dessel, Belgium, May 13-19, 1982. This instrument was developed under ISPO Tasks A-9 and A-47 at Argonne National Laboratory and was supplied to the IAEA through the U.S support program. Five containers of plutonium-oxide feed stock used in the manufacture of mixed-oxide LMFBR-type fuel were assayed during the test. Electrical measurements to verify the calibration of the calorimeter were also made

[en] The second physical inventory verification (PIV) exercise for IAEA inspectors was conducted at a US MOX fabrication facility (WHC) under the auspices of BNL/ISPO in 1984. The IAEA bulk calorimeter was introduced into this exercise. Completely non-destructive calorimetric assay was performed using gamma-ray isotopic measurements. The calorimetric assay measurements on selected items from several strata were used to generate HLNC calibration curves completely independent of operator's values. Outliers from HLNC measurements were also measured by calorimetric assay to demonstrate an in-field alternative to withdrawing aliquots for chemical assay. This exercise demonstrated that the IAEA now has the capability of applying calorimetric assay for these purposes. 3 refs., 3 figs., 3 tabs

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[en] Argonne National Laboratory is decommissioning a facility used to fabricate reactor fuel elements. The equipment is contaminated with alpha emitters at levels up to 10¹² dpm/100 cm². The objective of decontamination is to reduce the TRU concentrations below 10 nCi/g of waste. A portable NDA procedure using NaI(T1) gamma-spectrometric techniques was selected to measure the residual Pu and ²⁴¹Am in the glove boxes. Assays were performed at different stages in the decontamination process to estimate the detection system sensitivity and the effectiveness of the cleaning efforts