The Thorium Molten Salt Reactor : Moving on from the MSBR

A re-evaluation of the Molten Salt Breeder Reactor concept has revealed problems related to its safety and to the complexity of the reprocessing considered. A reflection is carried out anew in view of finding innovative solutions leading to the Thorium Molten Salt Reactor concept. Several main constraints are established and serve as guides to parametric evaluations. These then give an understanding of the influence of important core parameters on the reactor's operation. The aim of this paper is to discuss this vast research domain and to single out the Molten Salt Reactor configurations that deserve further evaluation.Comment: 11 pages, 8 figures, 6 table

Production of photons by the parametric resonance in the dynamical Casimir effect

We calculate the number of photons produced by the parametric resonance in a cavity with vibrating walls. We consider the case that the frequency of vibrating wall is $n \omega_1 (n=1,2,3,...)$ which is a generalization of other works considering only $2 \omega_1$, where $\omega_1$ is the fundamental-mode frequency of the electromagnetic field in the cavity. For the calculation of time-evolution of quantum fields, we introduce a new method which is borrowed from the time-dependent perturbation theory of the usual quantum mechanics. This perturbation method makes it possible to calculate the photon number for any $n$ and to observe clearly the effect of the parametric resonance.Comment: 15 pages, RevTeX, no figure

Fast Thorium Molten Salt Reactors started with Plutonium

One of the pending questions concerning Molten Salt Reactors based on the 232Th/233U fuel cycle is the supply of the fissile matter, and as a consequence the deployment possibilities of a fleet of Molten Salt Reactors, since 233U does not exist on earth and is not yet produced in the current operating reactors. A solution may consist in producing 233U in special devices containing Thorium, in Pressurized Water or Fast Neutrons Reactors. Two alternatives to produce 233U are examined here: directly in standard Molten Salt Reactors started with Plutonium as fissile matter and then operated in the Th/233U cycle; or in dedicated Molten Salt Reactors started and fed with Plutonium as fissile matter and Thorium as fertile matter. The idea is to design a critical reactor able to burn the Plutonium and the minor actinides presently produced in PWRs, and consequently to convert this Plutonium into 233U. A particular reactor configuration is used, called unique channel configuration in which there is no moderator in the core, leading to a quasi fast neutron spectrum, allowing Plutonium to be used as fissile matter. The conversion capacities of such Molten Salt Reactors are excellent. For Molten Salt Reactors only started with Plutonium, the assets of the Thorium fuel cycle turn out to be quickly recovered and the reactors characteristics turn out to be equivalent to Molten Salt Reactors operated with 233U only. Using a combination of Molten Salt Reactors started or operated with Plutonium and of Molten Salt Reactors started with 233U, the deployment capabilities of these reactors fully satisfy the condition of sustainability

Probing neutron-hidden neutron transitions with the MURMUR experiment

MURMUR is a new passing-through-walls neutron experiment designed to constrain neutron/hidden neutron transitions allowed in the context of braneworld scenarios or mirror matter models. A nuclear reactor can act as a hidden neutron source, such that neutrons travel through a hidden world or sector. Hidden neutrons can propagate out of the nuclear core and far beyond the biological shielding. However, hidden neutrons can weakly interact with usual matter, making possible for their detection in the context of low-noise measurements. In the present work, the novelty rests on a better background discrimination and the use of a mass of a material - here lead - able to enhance regeneration of hidden neutrons into visible ones to improve detection. The input of this new setup is studied using both modelizations and experiments, thanks to tests currently performed with the experiment at the BR2 research nuclear reactor (SCK$\cdot$CEN, Mol, Belgium). A new limit on the neutron swapping probability p has been derived thanks to the measurements taken during the BR2 Cycle 02/2019A: $p < 4.0 \ \times 10^{-10}$ at 95% CL. This constraint is better than the bound from the previous passing-through-wall neutron experiment made at ILL in 2015, despite BR2 is less efficient to generate hidden neutrons by a factor 7.4, thus raising the interest of such experiment using regenerating materials.Comment: 15 pages, 8 figures, final version, accepted for publication in European Physical Journal

Le Thorium Molten Salt Reactor : Au-delà du MSBR

La re-évaluation du concept de Molten Salt Breeder Reactor a fait apparaître des problèmes liés à la sûreté et à la complexité du retraitement. Une nouvelle réflexion est menée afin de trouver des solutions et ainsi d'aboutir au concept du Thorium Molten Salt Reactor. Plusieurs contraintes principales sont établies et vont servir de guides aux études paramétriques. Celles-ci permettent alors de comprendre l'influence de paramètres importants du coeur sur le comportement du réacteur. Le but de cet article est de présenter ce vaste domaine de recherche et d'indiquer quelles configurations intéressantes de Réacteurs à Sels Fondus peuvent être étudiées plus avant

Interference phenomena in the photon production between two oscillating walls

We study the photon production in a 1D cavity whose left and right walls oscillate with the frequency $\Omega_{L}$ and $\Omega_{R}$, respectively. For $\Omega_{L} \neq \Omega_{R},$ the number of generated photons by the parametric resonance is the sum of the photon numbers produced when the left and the right wall oscillates separately. But for $\Omega_{L} = \Omega_{R}$, the interference term proportional to $\cos \phi$ is found additionally, where $\phi$ is the phase difference between two oscillations of the walls.Comment: 7 pages, RevTeX, no figures, a sign error correcte

Association between maternal micronutrient status, oxidative stress and common genetic variants in antioxidant enzymes at 15 weeks’ gestation in nulliparous women who subsequently develop pre-eclampsia

Aims: Pre-eclampsia is a pregnancy-specific condition affecting 2-7% of women and a leading cause of perinatal and maternal morbidity and mortality. Deficiencies of specific micronutrient antioxidant activities associated with copper, selenium, zinc and manganese, have previously been linked to pre-eclampsia at time of disease. Our aims were to investigate whether maternal plasma micronutrient concentrations and related antioxidant enzyme activities are altered prior to pre-eclampsia onset and to examine the dependence on genetic variations in these antioxidant enzymes. Methods: Pre-disease plasma samples (15+1 weeks’ gestation) were obtained from women enrolled in the international SCreening fOr Pregnancy Endpoints (SCOPE) study who subsequently developed pre-eclampsia (n=244), and age- and BMI-matched normotensive controls (n=472). Micronutrient concentrations were measured by inductively coupled plasma mass spectrometry; associated antioxidant enzyme activities, selenoprotein-P, caeruloplasmin concentrations and activities, antioxidant capacity and markers of oxidative stress were measured by colorimetric assays. Sixty four tagSNPs within genes encoding the antioxidant enzymes and selenoprotein-P were genotyped using allele-specific competitive PCR. Results: Plasma copper and caeruloplasmin concentrations were modestly, but significantly elevated in women who subsequently developed pre-eclampsia (both P<0.001) compared to controls (median [IQR], copper: 1957.4 [1787, 2177.5] vs. 1850.0 [1663.5, 2051.5] µg/L; caeruloplasmin: 2.5[1.4, 3.2] vs. 2.2[1.2, 3.0] µg/ml). There were no differences in other micronutrients or enzymes between groups. No relationship was observed between genotype for single nucleotide polymorphisms (SNPs) and antioxidant enzyme activity. Conclusions: This analysis of a prospective cohort study reports maternal micronutrient concentrations in combination with associated antioxidant enzymes and SNPs in their encoding genes in women at 15 weeks’ gestation that subsequently developed pre-eclampsia. The modest elevation in copper may contribute to oxidative stress, later in pregnancy, in those women that go on to develop pre-eclampsia. The lack of evidence to support the hypothesis that functional SNPs influence antioxidant enzyme activity in pregnant women argues against a role for these genes in the aetiology of pre-eclampsia

Dynamical Casimir effect at finite temperature

Thermal effects on the creation of particles under the influence of time-dependent boundary conditions are investigated. The dominant temperature correction to the energy radiated by a moving mirror is derived by means of response theory. For a resonantly vibrating cavity the thermal effect on the number of created photons is obtained non-perturbatively. Finite temperatures can enhance the pure vacuum effect by several orders of magnitude. The relevance of finite temperature effects for the experimental verification of the dynamical Casimir effect is addressed.Comment: 9 LaTex page

Trembling cavities in the canonical approach

We present a canonical formalism facilitating investigations of the dynamical Casimir effect by means of a response theory approach. We consider a massless scalar field confined inside of an arbitaray domain $G(t)$, which undergoes small displacements for a certain period of time. Under rather general conditions a formula for the number of created particles per mode is derived. The pertubative approach reveals the occurance of two generic processes contributing to the particle production: the squeezing of the vacuum by changing the shape and an acceleration effect due to motion af the boundaries. The method is applied to the configuration of moving mirror(s). Some properties as well as the relation to local Green function methods are discussed. PACS-numbers: 12.20; 42.50; 03.70.+k; 42.65.Vh Keywords: Dynamical Casimir effect; Moving mirrors; Cavity quantum field theory; Vibrating boundary