Ramnicu Valcea Research Articles

Design, Fabrication, and Test of a Prototype of Matrix Heat Exchanger for Cryogenic Distillation of Hydrogen Isotopes

The following properties are needed to increase the efficiency of refrigeration, liquefaction, and cryogenic separation cycles: Heat exchangers must have high effectiveness doubled by high compactness; small temperature differences between incoming and outgoing flows must be ensured to increase efficiency; there must be a large heat transfer surface, relative to the volume of the heat exchanger, to minimize heat loss; there must be a high heat transfer rate to reduce the transfer area; there must be a small pressure drop to reduce compression costs; and there must be high reliability with minimal maintenance. All these properties are entirely fulfilled by the designed matrix heat exchangers (MHEs). This paper presents the results of the research program developed by the team of the Cryogenic Laboratory from INC-DTCI ICSI Ramnicu Valcea, which included procedural stages of the realization and preliminary results of the characterization of the MHE-type heat exchanger in a narrow range of values to achieve a proper solution for a heat exchanger to be used for cryogenic purposes, such as cooling the gas mixture at the entrance of a distillation column of hydrogen isotopes and running at low pressure (typically regimes of 0.5 to 2.0 bars) and flows. Within several experimental campaigns, different assembly and testing techniques of the matrix heat exchanger (MHE) prototype were performed to achieve numerical data for the temperature and pressure drops along the heat exchanger and to verify ANSYS Fluent numerical simulation results. The results showed that for the designed and tested MHE prototype, a temperature drop of up to almost 230 K can be obtained at the established parameters correlated with pressure losses within a few millibars (the maximum recorded pressure drop is 80 mbars), small dimensions (64 mm high), and accessible weight (up to 2000 g).

Finanțarea, promovarea și valorificarea științifică a revistei „Arhivele Olteniei” (1922–1946

In Oltenia, both within modern times and the interwar period, Craiova has distinguished as the most significant historical, economic and cultural centre. Culturally, „Arhivele Olteniei” enlists as „one of the most valuable” publications of the time diverting from the other prints by its encyclopaedic profile. Begins in 1922, at the initiative of doctor Charles Laugier as head and an editorial board made up of teachers and specialists: Stefan Ciuceanu (Craiova), T. G. Bulat (Ramnicu Valcea), Al. Barcacila (Tr. Severin), C. D. Fortunescu- the editorial secretary, as a quarterly publication and the forthcoming year as bimonthly issue. Dr. Laugier reports that the idea of editing this kind of journal is earlier, but he hesitated a lot mainly due to financial difficulties which publications faced overall, but particularly the scientific ones at that time. Although the threat of closing the publisher for material causes frequently hovered over the journal, it managed to emerge and to be valued for two decades. Ion Bianu appreciated ”Arhivele Oltenei” journal as „an invaluable treasure” for current and future historians.

THE IMPACT OF EXPERIMENTAL PILOT FOR TRITIUM AND DEUTERIUM SEPARATION ACTIVITY ON TRITIUM LEVEL IN THE ATMOSPHERIC WATER VAPOR OF ICSI TRITIUM LABORATORY

Results obtained from the monitoring of the ambient air of the ICSI Ramnicu Valcea Tritium Laboratory and the monitoring of the atmosphere around the Experimental Pilot Plant for Tritium and Deuterium Separation are used in the environmental impact evaluation of the experiments in the period 2020-2022. Even though the experiments carried out involved different tritium activity concentrations, there were no increases in the activity of tritium concentration in the analyzed samples, with numerous results of atmospheric samples being below the detection limit.

GEOLOGICAL AND GEOPHYSICAL CONSIDERATIONS REGARDING THE MINERAL AND GEOTHERMAL WATERS FROM THE RAMNICU VALCEA - GOVORA AREA

For understanding of complex geological and geophysical phenomena, regarding the mineral and geothermal waters, we must base on the whole of knowledge and available data for the study area. The input data include: digital terrain models, geological and geophysical maps, sections, drill-holes and geological interpretation, for assemble together into the same space data from various sources, in order to ensure geometrical coherence. Also, the database includes measurements of deuterium (δD (‰)) and overall salt content (∆d (mg/l)) expressed as the difference in density between a distilled water taken as a standard and water sample. Are important to take into account the geology 'boundary' data (geology contacts, interfaces and limits), the deep geology and processing/filtering of geophysical data with properly algorithms. The type of filtering of gravimetric and magnetic data must be chosen based on the depth of the model we want to get. This is necessary because the values of the geophysical parameters recorded at the surface of the terrain contain weighted average information from both the surface and from different depths, even to the base of the Lithosphere. In this paper we made some geological and geophysical considerations regarding the mineral and geothermal waters from the Ramnicu Valcea - Govora area. The types of water sources targeted are mineral springs, boreholes and surface water in the area

The influence of agricultural and industrial activities on the quality of water from public wells located in Ramnicu Valcea County

The aim of this study was to evaluate the quality of groundwater in an area with agricultural and industrial influences, located in Valcea County. Groundwater samples were collected in 2 campaigns from 14 public wells and were analyzed for pH, conductivity (EC), arsenic (As), cadmium (Cd), chromium (Cr), iron (Fe), manganese (Mn), nickel (Ni), lead (Pb), zinc (Zn), copper (Cu), nitrites (NO2-), nitrates (NO3+), ammonium (NH4+) and chlorides (Cl-). In most of the studied public wells, the laboratory results obtained for the physical-chemical parameters were within the limits imposed by the national legislation and those approved by the WHO. High levels of iron and manganese of natural origin were found at a public well located in a rural area and also chlorides at a well from an industrial area that exceeds the limits imposed.

Time series analysis of the δ 2 H, δ 18 O and d excess values in correlation with monthly temperature, relative humidity and precipitation in Râmnicu Vâlcea, Romania: 2012–2018

Abstract To investigate the influence of local climate and transboundary circulation of moisture on the stable isotope of precipitation in Ramnicu Valcea, Romania, monthly values of δ 2 H, δ 18 O, deuterium excess (d excess ), temperature, relative humidity and precipitation were determined between January 2012 and December 2018. Monthly analysis showed differences in d excess varying between 24.2‰ (October 2015) and −23.7‰ (July 2013) with a multi-annual average of 6.1 ± 5.9‰, suggesting an Atlantic origin of moisture with episodic Mediterranean transport. Also a significant correlation between the North Atlantic Oscillation on the local temperature during winter season was noticed. The local meteoric water line (LMWL) for the entire period showed slope and intercept values similar to those for neighbouring localities with the same altitude. When the analysis was extended to summer (April–October) and winter (November–March) seasons, the LMWL slope and intercept were different, reflecting the summer–winter difference in temperatures and air circulation. The monthly values of all parameters formed equal-spaced time series whose detailed analysis confirmed at p < 0.01 that δ 2 H, δ 18 O, temperature and relative humidity show a well-evidenced one-year periodicity. In contrast, precipitation and d excess seasonality were almost unrecognizable, most probably owing to the reduced number of observations.

Radiocarbon level in the Atmosphere of Ramnicu Valcea, Romania

ABSTRACTThis paper presents radiocarbon (14C) variations in the atmosphere from Ramnicu Valcea, Romania. The samples were collected in the vicinity of the Experimental Pilot Plant for Tritium and Deuterium Separation (PESTD) from the Institute of the Cryogenics and Isotopic Technologies (ICSI) placed about 10 km south from the Ramnicu Valcea city (Romania), in the Govora industrial area. This facility is an experimental project in the national nuclear energy research program, which has the aim of developing technologies for tritium separation from heavy water. It should be noted that in the Govora industrial area operates a 315 MW coal-fired thermoelectric power plant and two chemical plants. In order to determine radiocarbon activity in the atmosphere, samples were collected monthly by absorption of CO2 into sodium hydroxide (NaOH) at Ramnicu Valcea. In addition, control materials (tree leaves, wild vegetation, and grapes), known activity standards, and process blanks (marble) were analyzed. Radiocarbon measurements were performed using the direct absorption method and liquid scintillation counting. The measured Δ14C levels varied between –57‰ and 61‰. The results have a decreasing trend, but due to local influence caused by the continuous production of fossil CO2, we cannot observe Δ14C seasonal variations.

Multi-criteria analysis of suitable technologies for the tritium removal system in Valcea D-T Pilot Plant

A pilot plant for tritium removal from tritiated water is in pre-operational stage at ICSI Ramnicu Valcea and it’s based on catalytic isotopic exchange process (LPCE) between tritiated water and hydrogen/deuterium gas followed by cryogenic distillation (CD), aiming to recover tritium. As any detritiation plant or tritium processing plant/laboratory, the Experimental Pilot Plant for D-T separation (PESTD) from Rm. Valcea requires a tritium removal system (TRS) with the main purpose to recover tritium from purge gases used during maintenance of the technological systems prior to their discharge to environment and during normal operation of the plant. TRS is continuously connected to the tritiated water tanks within the plant for pressure management, similar as for ITER-WDS. In the specific case of the PESTD, TRS was given a secondary active role and that is to operate as follows: the gas inventory within CD could be reduce to water and returned to LPCE system in order to process it.This paper will present a multi-criteria analysis of the available technologies for the purpose of the TRS, together with a general schematic of the process selected and under implementation and some specifications of the equipment that constitute the final concept of the system.

18 years of continuous observation of tritium and atmospheric precipitations in Ramnicu Valcea (Romania): A time series analysis

To get more information on the origin of tritium and to evidence any possible presence of anthropogenic sources, between January 1999 and December 2016, the precipitation level and tritium concentration were monthly recorded and investigated by the Cryogenic Institute of Ramnicu Valcea, Romania. Compared with similar data covering a radius of about 1200 km westward, the measurements gave similar results concerning the time evolution of tritium content and precipitation level for the entire time interval excepting the period between 2009 and 2011 when the tritium concentrations showed a slight increase, most probable due to the activity of neighboring experimental pilot plant for tritium and deuterium separation. Regardless this fact, all data pointed towards a steady tendency of tritium concentrations to decrease with an annual rate of about 1.4 ± 0.05%. The experimental data on precipitation levels and tritium concentrations form two complete time series whose time series analysis showed, at p < 0.01, the presence of a single one-year periodicity whose coincident maximums which correspond to late spring - early summer months suggest the existence of the Spring Leak mechanism with a possible contribution of the soil moisture remobilization during the warm period.

EVALUATION OF HEAVY METAL POLLUTION INTO A COMPLEX INDUSTRIAL AREA FROM ROMANIA

The work studies the degree of heavy metal pollution in water, sediment and soil in the industrial platform area from Ramnicu Valcea, Romania. The water and sediment samples were collected from three locations of the Olt River, in two distinct periods, February and June 2010. Concentrations of nickel, copper and cadmium were analyzed. The soil samples were collected from eight points and the same elements were analyzed, in the above mentioned interval of time. The results of water and sediment analyzes were compared with legally prescriptions from the norms regarding surface water quality classification in order to determine the ecological status of water bodies. The soil samples were compared with reference values for the trace of the chemical elements in the soil. In the upstream section of the platform, heavy metals concentrations in sediments exceed limits imposed by national regulations. In downstream sections concentration of nickel, copper and cadmium are generally within the imposed limits. Concentrations of heavy metals in water were lower than National and European legislation limits. The degree of the heavy metals pollution changes, depend on wastewaters industrial flow of the chemical platform. In case of soil samples, the nickel, copper and cadmium concentrations don t exceed the limits values of the environmental legislation.

Tritium time series in precipitation of Rm. Valcea, Romania

ABSTRACTFollowing tritium concentration records in precipitation for the period 1999–2013 and tritium concentration behaviour during this period for the Ramnicu Valcea (Rm. Valcea) location, the tritium level of individual precipitations of the late spring and summer for the 2009–2013 period was investigated. Despite good correlation between monthly mean tritium concentrations and monthly mean precipitations over the 15-year period of observations (Pearson coefficient 0.87), the individual precipitations had no linear correlation between the tritium concentration and the amount of precipitation.

The influence of surface coverage on the catalytic activity of silica-supported heteropolyacids

A series of heteropolyacid (HPA)—silica composites were prepared from H3PMo12O40 (HPM) and H4PVMo11O40 (HPVM) by supporting on two types silica supports: Aerosil–Degussa and Romsil–Ramnicu Valcea with different active phase concentrations. The structure and texture of these HPA/silica composites were studied by XRD, FT-IR spectroscopy and nitrogen physisorption at 77 K. The effect of the support on the thermal stability was investigated by TG-DTG and DTA. By the deposition of heteropolyacids on silica type supports, an important decrease of thermal stability was observed on Romsil types and a small decrease on Aerosil types. By comparing with initial supports, the specific surface areas of HPAs deposited on all supports decreased with the active phase concentration. The catalytic properties of the prepared samples were studied by using a reactant pulse method at different temperatures. The ethanol conversion proceeds by two main pathways: an oxide hydrogenation reaction on redox catalytic centers with acetaldehyde formation, and a dehydration reaction on acidic centers with ethylene and diethyl ether formation. The reaction rates of ethanol conversion and acetaldehyde formation increased on supported HPA compared to bulk HPA. The favorable effect of HPAs deposition on silica supports for the oxidehydrogenation pathway to acetaldehyde results from the examination of apparent activation energies Ea and reaction rate values. Evidence of decreasing Ea was obtained for acetaldehyde formation in the case of silica Romsil-supported HPM (39.6 kJ/mol) comparatively with bulk HPM (56.6 kJ/mol). For all reaction temperatures, the reaction rates of acetaldehyde formation are higher for supported samples than unsupported ones.

Using stable isotopes in tracing contaminant sources in an industrial area: A case study on the hydrological basin of the Olt River, Romania

Tracing pollution sources and transformation of nitrogen compounds in surface- and groundwater is an issue of great significance worldwide due to the increased human activity, translated in high demand of water resources and pollution. In this work, the hydrological basin of an important chemical industrial platform in Romania (Ramnicu Valcea industrial area) was characterized in terms of the physico-chemical and isotope composition of δ18O and δ2H in water samples and δ15N of the inorganic nitrogen species. Throughout a period of one year, water samples from the Olt River and its more important tributaries were collected monthly in the industrial area, when the seasonal and spatial isotope patterns of the surface waters and the main sources of pollution were determined. Higher inorganic nitrogen concentrations (up to 10.2mgNL−1) were measured between November 2012 and April 2013, which were designated as anthropogenic additions using the mixing calculations. The main sources of pollution with inorganic nitrogen were agriculture and residential release. The inorganic nitrogen from the industrial waste water duct had a distinct δ15N fingerprint (mean of −8.6‰). Also, one industrial release into the environment was identified for Olt River, at Ionesti site, in November 2012. The mean precipitation samples had the lowest inorganic nitrogen concentrations (less than 5.5mgNL−1) with a distinct δ15N fingerprint compared to the surface and industrial waters.

Study about sorption of protium and mixture protium–tritium on sponge titanium

The Nuclear Power Plant Cernavoda is equipped with a CANDU reactor and is one of the most powerful tritium sources from Europe. The reactor is moderated and cooled with heavy water that is continuous enriched with tritium. The presence of the tritium decreases the capacity of the heavy water to moderate the nuclear reactions. For this reason, I.C.I.T. Ramnicu Valcea developed a detritiation technology based on catalytic isotopic exchange and cryogenic distillation. At the end of the detritiation process, heavy water is produced with low concentration of tritium (that could be introduced back for the moderation process) and tritium (that have to be stored into a stable form). Tritium is a radioactive material and one of the basic conditions for the operation of the nuclear installations is the security for the operating personnel and for the environment [1]. At I.C.I.T. Ramnicu Valcea were tested materials with high capacity for storage of tritium, like titanium sponge and powder. The first experimental study was made using protium because it was assumed that tritium behaves similar with protium. In addition, it was made experiments of sorption on sponge titanium using a mixture protium–tritium. The result was similar but not identical, titanium sponge absorbing better protium than mixture protium–tritium, resulting different atomic ratios. The paper presents a study about sorption of protium and mixture of protium and tritium on sponge titanium.

IMPEDIMENTS IN IMPLEMENTING LOCAL AGENDA 21 IN ROMANIA: A CASE STUDY OF RAMNICU VALCEA STRATEGY FOR SUSTAINABLE DEVELOPMENT

This article identifies and discusses the difficulties the main actors involved in the process of Local Agenda 21 implementation are confronted with in countries in transition as Romania. These are mainly the lack of financial resources, a weak connection of the academic world with the policy-making process, difficulties in adopting a "multistakeholders" strategy and sometimes a weak legal framework. However, specific problems characteristic for a country in transition and reminiscences of the communist regime imprint a special profile to the process of implementation of Local Agenda 21 in Romania. The solution to these problems may reside in the opening of the Romanian society to an external flux of funds and information, as well as in surpassing the weak communist thinking, which has unfortunately been maintained over years. To reach its purpose, the paper analyses the instrument for Local Agenda 21 implementation in a Romanian municipality, Ramnicu Valcea.