Reducing the radioactive doses of liquid samples taken from reprocessing plant vessels by volume reduction

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The real time mass evaluation system as a tool for detection of undeclared cascade operation at GCEPs

Given the flexibility of current cascade designs a real time mass monitoring system is preferred for safeguarding Gas Centrifuge Enrichment Plants. However, if such a system is to be installed in a GCEP it must not impinge on plant operation or be intrusive. Since load cells are already part of the operational process and located outside the cascade hall their exploitation for safeguards purposes is an obvious development. The paper describes, through dynamic simulations, how transients would be observed in real-time mass balances when undeclared cascade operation takes place in a declared facility

Neutron and gamma-ray cross-correlation measurements of plutonium oxide powder

a b s t r a c t For the first time, measurements of the time-dependent cross-correlation distributions of plutonium oxide have been made separately for neutrons and gamma rays. Six EJ-309 liquid scintillation detectors with a digital, offline pulse shape discrimination and pulse timing method were used to measure five different samples of varying mass and burnup. The number of (neutron, neutron) correlations were selectively analyzed versus plutonium mass and a clear, increasing trend was observed. Additionally, the measurement scenarios were modeled using the MCNP-PoliMi code and good agreement was observed between the measured and simulated cross-correlation functions

Special nuclear material detection studies with the SMANDRA mobile system

The detection of special nuclear material has been studied with the SMANDRA mobile inspection system used both as a high sensitivity passive neutron/gamma spectroscopic tool and as an active inspection device using tagged neutrons. The detection of plutonium samples is possible with passive interrogation, the passive detection of uranium being much more difficult because of the low neutron yield and of the easiness of shielding the gamma rays. However, we show that active interrogation with tagged neutrons is able to provide signatures for the discrimination of uranium against other materials

Fast neutron spectrum unfolding for nuclear nonproliferation and safeguards applications

We present new neutron spectrum unfolding results obtained from measurements with Cf-252 and plutonium-oxide sources. The precise knowledge of the neutron energy spectrum provides information about the presence or absence of fissile material and about the characteristics of the material. We used a neutron spectrum unfolding technique based on a modification of the least-squares method. The main innovation is the use of a Krylov subspace iteration which performs better on ill-conditioned systems of linear equations than standard direct-solution methods. The proposed technique performed well in the unfolding of measured neutron pulseheight distributions from a Cf-252 neutron source and from plutonium-oxide samples and could be easily implemented in a portable neutron spectroscopy system for nuclear nonproliferation and safeguard applications

Extracellular matrix educates an immunoregulatory tumor macrophage phenotype found in ovarian cancer metastasis

: Recent studies have shown that the tumor extracellular matrix (ECM) associates with immunosuppression, and that targeting the ECM can improve immune infiltration and responsiveness to immunotherapy. A question that remains unresolved is whether the ECM directly educates the immune phenotypes seen in tumors. Here, we identify a tumor-associated macrophage (TAM) population associated with poor prognosis, interruption of the cancer immunity cycle, and tumor ECM composition. To investigate whether the ECM was capable of generating this TAM phenotype, we developed a decellularized tissue model that retains the native ECM architecture and composition. Macrophages cultured on decellularized ovarian metastasis shared transcriptional profiles with the TAMs found in human tissue. ECM-educated macrophages have a tissue-remodeling and immunoregulatory phenotype, inducing altered T cell marker expression and proliferation. We conclude that the tumor ECM directly educates this macrophage population found in cancer tissues. Therefore, current and emerging cancer therapies that target the tumor ECM may be tailored to improve macrophage phenotype and their downstream regulation of immunity