Myrrha primary heat exchanger tube rupture: Phenomenology and evolution

In the framework of MYRRHA Project, a pool-type experimental and material testing irradiation facility operated with Lead Bismuth Eutectic (LBE) coolant and able to operate in both sub-critical and critical mode is designed to be built in Mol, Belgium, in SCK\u2022CEN domain. In addition to the material testing function, targets of the MYRRHA reactor are to prove the feasibility of the ADS technology as Minor Actinides (MAs) burner and to act as a demonstrative plant for future Gen-IV heavy metal cooled reactors. SCK\u2022CEN entered the pre-licensing phase for the MYRRHA reactor. In order to provide the safety authority all the required data, a complete safety analysis must be performed, studying the transients defined by the list of postulating initiating events. In particular, an accident with potential serious consequences is the Primary Heat Exchanger Tube Rupture (PHXTR), involving the sudden release of single phase or two-phase water from a tube break in a hot liquid metal pool. This accident evolution is strongly characterized by the design of the MYRRHA Primary Heat eXchanger (PHX) and its direct surroundings in the reactor vessel and by the thermal-hydraulical conditions of the MYRRHA primary and secondary cooling system. In the first phase of a PHXTR accident, the water in the Secondary Cooling System (SCS) is released in the Primary System (PS) pool in regime of choked flow due to the pressure difference. Being the water released in an overheated, low-pressure environment, a flashing with potential sudden specific volume increase is expected. The heat transfer phenomena leading to the phase change velocity depend by the actual number of bubbles released in the hot liquid metal pool, function of the actual break size and shape. Its characterization is important for the definition of the overall specific volume increase and for the estimation of the water mass fraction redirected through the Primary Pump in the reactor Lower Plenum, with the risk of void insertion in the core and consequent reactivity excursion. A simplified calculation model to evaluate the history of any given bubble distribution generated by any water flow rate through any break has been set up. The main purpose is to describe the evolution of the main system state variables during the accidental event, by checking the potential insurgency of any reactor safety issue due to pressure peaks or core void insertions

Bio-based benzoxazines synthesized in a deep eutectic solvent: A greener approach toward vesicular nanosystems

A green synthesis of benzoxazines, based upon reaction of cardanol with formaldehyde and primary amines, is achieved in high yields using choline chloride-urea mixture as deep eutectic solvent. Then, it is demonstrated how the cardanol-based benxoxazines can be employed as only component for the preparation of a nanovesicular systems

Determination of carbonyl compounds in exhaled breath by on-sorbent derivatization coupled with thermal desorption and gas chromatography-tandem mass spectrometry

A reliable method for the determination of carbonyl compounds in exhaled breath based on on-sorbent derivatization coupled with thermal desorption and gas chromatography-tandem mass spectrometry is described. The analytical performances were optimized for a mixture of C2-C9 aldehydes and C3-C9 ketones, particularly interesting for clinical applications, by using an internal standard and applying a 2^3 full factorial design. A volume of sample (250 ml) was loaded at 50 ml min-1 into a Tenax GR sorbent tube containing 130 nmol of O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine hydrochloride. All compounds showed a limit of detection lower than 200 pptv. The yield of the derivatization procedure was normalized by adding to the sample a known amount of 6D-acetone as an internal standard. This allowed halving the relative standard deviation to 10% and 15% for the mono-and di-carbonyl compounds, respectively, thus improving reliability. The optimized method was applied to the determination of carbonyl compounds in 12 breath samples collected from four patients suffering from heart failure during hospitalization

An algebraic classification of entangled states

We provide a classification of entangled states that uses new discrete entanglement invariants. The invariants are defined by algebraic properties of linear maps associated with the states. We prove a theorem on a correspondence between the invariants and sets of equivalent classes of entangled states. The new method works for an arbitrary finite number of finite-dimensional state subspaces. As an application of the method, we considered a large selection of cases of three subspaces of various dimensions. We also obtain an entanglement classification of four qubits, where we find 27 fundamental sets of classes.Comment: published versio

Analysis of radiatively stable entanglement in a system of two dipole-interacting three-level atoms

We explore the possibilities of creating radiatively stable entangled states of two three-level dipole-interacting atoms in a $\Lambda$ configuration by means of laser biharmonic continuous driving or pulses. We propose three schemes for generation of entangled states which involve only the lower states of the $\Lambda$ system, not vulnerable to radiative decay. Two of them employ coherent dynamics to achieve entanglement in the system, whereas the third one uses optical pumping, i.e., an essentially incoherent process.Comment: Replaced with the final version; 14 pages, 6 figures; to appear in Phys. Rev. A, vol. 61 (2000

Extending scientific computing system with structural quantum programming capabilities

We present a basic high-level structures used for developing quantum programming languages. The presented structures are commonly used in many existing quantum programming languages and we use quantum pseudo-code based on QCL quantum programming language to describe them. We also present the implementation of introduced structures in GNU Octave language for scientific computing. Procedures used in the implementation are available as a package quantum-octave, providing a library of functions, which facilitates the simulation of quantum computing. This package allows also to incorporate high-level programming concepts into the simulation in GNU Octave and Matlab. As such it connects features unique for high-level quantum programming languages, with the full palette of efficient computational routines commonly available in modern scientific computing systems. To present the major features of the described package we provide the implementation of selected quantum algorithms. We also show how quantum errors can be taken into account during the simulation of quantum algorithms using quantum-octave package. This is possible thanks to the ability to operate on density matrices

On manifolds with nonhomogeneous factors

We present simple examples of finite-dimensional connected homogeneous spaces (they are actually topological manifolds) with nonhomogeneous and nonrigid factors. In particular, we give an elementary solution of an old problem in general topology concerning homogeneous spaces