Jesús Martín Gil

Application of the Integrated Safety Assessment methodology to safety margins. Dynamic Event Trees, Damage Domains and Risk Assessment

The Integrated Safety Assessment (ISA) methodology, developed by the Consejo de Seguridad Nuclear, has been applied to an analysis of Zion NPP for sequences with Loss of the Component Cooling Water System (CCWS).

Synthesis under Pressure of Potential Precursors of CNx Materials Based on Melamine and Phenolic Resins

The cross-linking under pressure of a mixture of novolak and melamine resins with a weight ratio of 1 has been investigated by means of several techniques, including DSC, TGA, XRD, and IR. Four samples were prepared under varying pressure and temperature. The application of pressure to the reaction vessel favored the formation of a more structured cross-linked resin. The sample cross-linked at both the highest temperature and pressure levels exhibited higher structuring effects than the others. Moreover, this sample exhibited much higher thermal stability than the others. This achievement may allow us to open the pathway toward new precursors of structured CN x materials.

New carbon-nitrogen materials. A likely alternative to diamond

Abstract In a recent work Liu and Cohen ( Phys. Rev. B., 41 (1990) 10 727-10 734) reported the theoretical prediction of a C-N phase whose hardness was competing with that of diamond. This work provoked extensive experimental search for the theoretical material with a composition β -C 3 N 4 . There was a report (Niu, Lu and Lieber, Science, 261 (1993) 334–337) on the growth β -C 3 N 4 films. However, this has not been reproduced by others workers. Recently, Guo and Goddard ( Chem. Phys. Lett., 237 (1995) 72) reported that the synthesized material, in most cases, corresponds to α -C 3 N 4 and not to β -C 3 N 4 . We review the evidence from a number of papers and conclude that there is not enough evidence that C 3 N 4 can be produced as large crystals. It is clear, however, that the α -C 3 N 4 is more stable than the β -C 3 N 4 phase. We discuss the recent report (Sarikaya, Qian, Martin-Gil, Martin-Gil and Jose-Yacaman, to be published) in which a new phase with the composition α -C x N y with x 4 and y 4 is found. We discuss the applications and future trends on these materials.

Application of Integrated Safety Assessment Methodology to SBO Sequences

The integrated Safety Assessment (ISA) methodology, developed by the Spanish Nuclear Safety Council (CSN), has been applied to a thermal-hydraulic analysis of PWR Station Blackout (SBO) sequences in the context of the IDPSA (Integrated Deterministic-Probabilistic Safety Assessment) network objectives. The ISA methodology allows obtaining the damage domain (the region of the uncertain parameters space where the damage limit is exceeded) for each sequence of interest as a function of the operator actuations times (recovery of AC). Given a particular safety limit or damage limit, several data of every sequence are necessary in order to obtain the exceedance frequency of that limit. In this application these data are obtained from the results of the simulations performed with MAAP code transients inside each damage domain and the time-density probability distributions of the manual actions. Several damage limits have been taken into account within the analysis: local cladding damage (PCT>1477 K); local fuel melting (T>2499 K); fuel relocation in lower plenum and vessel failure. Therefore, to every one of these damage variables corresponds a different damage domain. The results show the capability and necessity of the ISA methodology, or similar, in order to obtain accurate results that take into account time uncertainties.Copyright

Quantitative risk reduction by means of recovery strategies

Abstract After the accident at Fukushima Dai-ichi, considerable efforts were put on enhancing the capability of the Nuclear Power Plants to cope with conditions resulting from the loss of plant safety-related systems. The most widespread solution adopted worldwide has been to define and implement new procedures and emergency actuation plans, the so called FLEX strategies. Among these strategies, there are several recovery strategies which involve the use of portable equipment for accomplishing the safety functions of the unavailable systems. In some cases, these strategies have been devised to be performed concurrently to the usual system recovery procedures included in the EOPs of most NPPs. In this regard, the heat sink recovery after the occurrence of a Total Loss of Feedwater (TLFW) in a Westinghouse 3-loop PWR design is a significant example, and it has been chosen in the present study to assess the quantitative risk reduction provided by the usual and FLEX recovery strategies in a Westinghouse 3-loop PWR design. With this aim, the Integrated Safety Assessment (ISA) methodology, developed by the Spanish Nuclear Safety Council (CSN), has been applied to TLFW sequences as part of the collaboration between Technical University of Madrid (UPM), NFQ Solutions and CSN.

Dynamic event trees without success criteria for full spectrum LOCA sequences applying the integrated safety assessment (ISA) methodology

Abstract The integrated safety assessment (ISA) methodology, developed by the Spanish nuclear safety council (CSN), has been applied to the analysis of full spectrum loss of coolant accident (FSLOCA) sequences in a 3-loop pressurized water reactor (PWR). The ISA methodology proposal starts from the unfolding of the dynamic event tree (DET), focusing on the uncertainty of a reduced set of sequence parameters. Outcomes from this step allow assessing the sequence delineation of standard probabilistic safety analysis (PSA) results. For some sequences of interest of the outlined DET, the following ISA methodology steps involve the identification of the damage domain (DD). This is the region of main uncertain parameters space where a safety limit is exceeded during a given sequence. This analysis illustrates the application of this concept, based on transient simulations using MAAP. From the information obtained from the DDs, and considering the time-density probability distributions of human actions and stochastic phenomena occurrence, ISA integrates the dynamic reliability equations proposed to obtain each sequence contribution to the damage exceedance frequency (DEF). The study is then extended to include the uncertainty of subsidiary parameters and, finally, a comparison between the ISA methodology application to FSLOCA and the classical PSA methodology is established.

Damage Domains Calculation Associated With Multiple Damages in a Steam Generator Tube Rupture Dynamic Event Tree

The Integrated Safety Assessment (ISA) methodology, developed by the Spanish Nuclear Safety Council (CSN), has been applied to a thermo-hydraulical analysis of a Westinghouse 3-loop PWR plant by means of the dynamic event trees (DET) for Steam Generator Tube Rupture (SGTR) sequences. The ISA methodology allows obtaining the Damage Domains of a SGTR Dynamic Event Tree taking into account the operator actuation times and system response time. The Damage Domains allow to quantify more exactly the risk associated with the sequence even if the contribution to the total risk is due to multiple damages, like dose and core damage in the case of a SGTR. The results shows the impact of the risk associated with the dose as an addition of the risk associated with the core damage. Simulations are performed with SCAIS (Simulation Code system for Integrated Safety Assessment), which includes a dynamic coupling with MAAP thermal hydraulic code.Copyright

Novel erbium (III) fluorinated β-diketonate ternary complexes for application in 1.5 μm emitting OLEDs

Novel near infra-red emitting erbium (III) fluorinated β-diketonate complexes with 5-NO2-1,10-phenanthroline as chelating N, N-donor molecule have been tested as active layers in solution processed organic light emitting diodes. The function of N, N molecule is to saturate the coordination sphere of the erbium ion and to harvest excitation light that can be transferred to the excited states of the erbium ion. Absorption, emission properties and 1.5 μm emission life time of the material in solution and in thin film are described. We describe the fabrication and characterization of solution processed organic light emitting diodes (OLEDs) based fabricated using single structure: glass/indiumtin oxide(ITO) / poly(3,4-ethylenedioxythiophene) / poly(4-styrenesulfonate) (PEDOT:PSS)/Er-complex/Ca/Al. These Er-complexes form very uniform thin films. The good electrical response, with low threshold voltages (a few volts), together with the very uniform thin films formed, made these complexes promising for IR emitting displays.