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Jitsukata, Shu*; *; ; ; Kurosawa, A.
JNC TN8410 2001-002, 66 Pages, 2000/12
JNC-TN8410-2001-002.pdf:2.03MB
It was required from IAEA to determine a small amount of plutonium in the high active liquid waste solutions (HALW) in the tokai reprocessing plant. High performance spectrophotometer (HPSP), which could be obtained lower detection limit than conventional spectrophotometer, is studied to be applied to the inspection and verification analysis by the IAEA. [Cold Test] Neodymium, showing an absorption peak near the absorption wavelength of plutonium (VI), was used as an alternative element to plutonium, in order to review the calculation method of the peak intensity. As a result, the three-point correction method was found to be simple and effective. [Hot Test] Plutonium nitrate solution was used the fundamental test of this method. Since the method is known to be influenced by acidity, suspended sludge and coexistent elements in a sample, each dependency was examined. It was found that measurement results varied about 14% at a nitric acid concentration of 2-4 mol/L. Sludge should be removed by filtration before the measurement. The effect of coexisting elements could be eliminated adjusting the optical balance between reference and sample beam intensity. In the case of measuring a low concentration plutonium solution sample, a ratio of the peak intensity to the background intensity (S/B ratio) is relatively small. Therefore a method should be improved the S/B ratio by analyzing the obtained spectra. Accumulated average method, moving average method and Fourier transform method was tested. The results showed that a combination of the accumulated average method and the moving average method was the optimum method for the purpose. Linearity of the calibration curve was found between 0-11 mgPu/L. Synthetic sample solution, which simulated the actual constituents of the HALW with plutonium showed a good linear relation at 0-11 mgPu/L. The detection limit for plutonium concentration was 0.07 mgPu/L. When the synthetic HALW solution containing plutonium was measured, the de
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JNC TN9400 2000-020, 54 Pages, 1999/11
JNC-TN9400-2000-020.pdf:2.36MB
A Laser-induced breakdown spectroscopy Leak Detection technique (abbreviated LLD) of sodium is accomplished by plasmafying the sodium aerosol, and then selectively detecting the sodium specific optical spectrum. This method is potentially more reliable as a means of detecting of sodium small leakage. This report, describes test results of detection characteristics using sodium aerosol, carried out to verify the principle of LLD in addition to evaluating the response under various conditions. 0ur main objective is to examine the applicability of LLD for small sodium leakage. The main results are as follows; (1)We confirmed the principle of LLD, specifically detecting the sodium optical spectru.m. (2)The relation between LLD fluorescence intensity and sodium aerosol concentration is nearly proportional within a relatively Na concentration ranges 10
10
g/cm
. (3)The LLD signal appeared insensitive to the effect of sampling gas flow rate, oxygen concentration, and humidity in the examined range. ln fact, a high S/N ratio is obtained for small sodium leakage, and the reliability of the leakage detection is high, because LLD showed sensitive to sodium concentration. From these results and others discussed in this report, LLD appears to be an applicable technique in small leakage detection both in terms of response and reliabilily in the leakage phase.
; Aoto, Kazumi;
JNC TN9400 99-061, 32 Pages, 1999/07
In this report, reconstruction of magnetic charges induced by mechanical damages in a test piece of SUS304 stainless steel is performed as a part of eforts to establish a passive nondestructive testing method on the basis of the inspection of leakage magnetic field. The approach for solving this typical ill-posed inverse problem is selected as a way in the least square method category. Concerning the ill-poseness of the system of equations, an iteration algorithm is adopted to its solving in which the designations of initial profile, the weight coefficients and the total number of iterations are taken as means of reqularization. From examples using simulated input data, it is verified that the approach gives good reconstruction results in case of signals with a relative high S/N ratio. For improving the robustness of the proposed method, a Galerkin procedure with base functions chosen as the Daubechies' wavelet is also introduced for discretizing the governing equation. By comparing the reconstruction results of the least square method and those using wavelet discretization, it is found that the wavelet used approach is more feasible in the inversion of noise polluted signals. Reconstruction of 1-D and 2-D magnetic charges with the least square strategy and reconstruction of an 1-D problem with the wavelet used method are carried out from both simulated and measured magnetic field signals which are used as the validation of the proposed inversion strategy.