Development of the method of isotopic correlations for determining the relative 242Pu content in plutonium samples

Abstract

One of the main problems in accounting for and monitoring plutonium is measuring periodically its mass and isotopic composition by nondestructive means. The only nondestructive method determining the isotopic composition of plutonium is γ spectrometry using high-resolution semiconductor detectors. The isotopic composition is calculated using programs for analyzing the γ spectra, such as FRAM (USA) or MGA (USA). The plutonium mass is evaluated using a combination of two methods: counting neutron coincidences + γ spectrometry or calorimetry + γ spectrometry. When neutron coincidences are counted, data on the isotopic composition are needed to calculate the effective 240 Pu fraction ( 240 Pu eff ): 240 Pu eff = 2.52 238 Pu + 240 Pu + 1.68 242 Pu,

Comparison of correlation relations for determining the relative 242Pu content in plutonium produced in the RT-1 plant at the Industrial Association Mayak

“…Relation (4) obtained for a much larger sample is almost identical to the one proposed in [4]. This confirms the correctness of the approach chosen.…”

“…It should be noted that the first algorithms of both programs differ only by a constant coefficient. A correlation relation for determining 242 Pu in the plutonium produced at the RT-1 plant of the Industrial Association Mayak was proposed previously [4]. It was obtained by analyzing the certificate data for 1100 isotopic compositions.…”

“…An important feature of correlation relation (4), (5) is that the decay of the plutonium isotopes in time is taken into account (Fig. 2).…”

Determination of the plutonium mass in containers with plutonium dioxide according to the γ radiation from spontaneous-fission products

“…In the present work, the nameplate data on a container with plutonium dioxide with different isotopic composition, which were obtained by means of mass-spectrometric analysis [6], were used to find the correlation relation. Its content is evaluated by the method of isotopic correlations, using data on the relative content of other plutonium isotopes in the sample.…”