Prompt reactivity determination in a subcritical assembly through the response to a Dirac pulse

The full understanding of the kinetics of a subcritical assembly is a key issue for its online reactivity control. Point kinetics is not sufficient to determine the prompt reactivity of a subcritical assembly through the response to a dirac pulse, in particular in the cases of a large reflector, a small reactor, or a large subcriticality.Taking into account the distribution of intergeneration times, which appears as a robust characteristic of each type of reactor, helps to understand this behaviour.Eventually, a method is proposed for the determination of the prompt reactivity. It provides a decrease rate function depending on the prompt multiplication coefficient Keffp. Fitting a measured decrease rate with this function, calculated once for the reactor, gives the true value of keffp. The robustness of the method is tested. (Elsevier

Potential of thorium molten salt reactors : detailed calculations and concept evolution with a view to large scale energy production

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Molten salt reactors and possible scenarios for future nuclear power deployment

PAC

Pseudoaneurysm of the peroneal artery: presentation of Ehlers-Danlos syndrome type IV.

INTRODUCTION: Pseudoaneurysms in deep or unusual sites raise the possibility of an underlying vessel wall disorder. REPORT: A 28-year-old woman presented with pain and swelling of her calf, with no history of trauma. Angiography diagnosed a peroneal artery pseudoaneurysm, which we embolised successfully. Subsequent genetic analysis revealed the COL3A1 mutation, confirming Ehlers-Danlos syndrome type IV. CONCLUSION: To our knowledge, this is the first report of a peroneal artery pseudoaneurysm associated with underlying collagen vascular disease

Backside failure analysis of GaAs MMIC ASICs

A case study of backside failure analysis is performed on failed MMIC ASIC devices sealed in SOP packages. The use of Benzocyclobutene (BCB) as a dielectric material, which is etched during wet etch front-side decapsulation, motivated the proposed backside approach. Due to the transparency of the GaAs substrate to near infrared wavelengths, innovative optical defect localization techniques can be used. In this paper we present the successful application of Thermal Laser Stimulation (OBIRCH, TIVA) to rapidly, non-destructively and precisely localize the defects through the GaAs substrate. Backside delayering allowing defect observation and revelation is also discussed. Finally, an electrical interpretation of the failure and the corrective actions are presented