DETERMINATION OF $sup 148$Nd IN IRRADIATED URANIUM AND PLUTONIUM AS A MEASURE OF BURNUP.

Abstract

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ZIRCALOY-CLAD UO$sub 2$ FUEL ROD EVALUATION PROGRAM. Quarterly Progress Report No. 10, February--April 1970.

“…( 1 ) Based on previous experience, the values obtained with the Ge(Li) system are estimated to be -5-correct within ±3 percent (1a). Specimens sectioned from four of the rods will be analyzed for burnup by the neodymium mass spectrometric method ( 2 ) and by the normal radiochemical determination of Cs-137. These analyses will provide a means of verifying the nondestructively determined relative burnup values and will furnish absolute values of exposure.…”

Evaluation of the irradiation-averaged fission yield for burnup determination in spent fuel assays

“…This last approximation implicitly considers infinite-dilution and neglects resonance and shielding aspects affecting neutron transport. It may seem a crude approximation of the actual irradiation conditions, but it should be noted that only the ratios of cross-sections will play a role in equation (2). The use of microscopic cross-sections in the approach will be evaluated and discussed in Section 4.…”

“…It is then difficult to chemically recover their entire inventory; this is the case for the metallic elements such as Mo, Tc, Ru, Rh, Ag & Pd. For all these reasons, the choice of burnup monitor is often limited to lanthanides, notably 144 Ce and the neodymium isotopes [1,2,12,35]. Of the neodymium isotopes, 148 Nd is often used as reference nuclide for burnup analysis, in view of the small difference of fission yield between the two dominant fissile isotopes 235 U and 239 Pu.…”

“…Coupled neutron transport and depletion calculations are generally validated against well documented spent nuclear fuel (SNF) assay data. Those assays often report, in addition to the spent nuclear fuel inventory, the experimental sample burnup [1][2][3][4][5][6][7][8][9][10][11][12]. The experimental burnup offers a simple way to cross-check the burnup or the power history calculated by the plant operator.…”