scholarly journals Release of fission products from irradiated SRP fuels at elevated temperatures: Data report on the second stage of the SRP source term study

1987 ◽  
Author(s):  
R E Woodley
Keyword(s):  
Source Term ◽  
Elevated Temperatures ◽  
Fission Products ◽  
Term Study ◽  
Second Stage

Temperature Dependence of Ar Sputtering of CoSi2 Thin Films on Si and SiO2

1991 ◽  
Vol 235 ◽  
Author(s):  
Q. Z. Hong ◽  
J. M. E. Harper
Keyword(s):  
Thin Films ◽  
Temperature Dependence ◽  
Etch Rate ◽  
Elevated Temperatures ◽  
Ion Sputtering ◽  
Second Stage ◽  
Silicide Layer ◽  
Initial Stage ◽  
Co Concentration ◽  
Argon Ion

ABSTRACTThe temperature dependence of 300 eV argon ion sputtering of CoSi2 thin films in the range 50–600°C has been investigated. At temperatures above 400°C, the etch rate of CoSi2 on Si is significantly reduced, while the underlying Si reacts with the Co atoms diffusing from the silicide surface. As a result, the silicide layer effectively moves into the substrate during Ar bombardment. During sputtering of CoSi2 on Sio2, the thickness of the silicide layer decreases almost linearly with bombarding time until all the silicide is removed. Similar behavior is observed in low temperature sputtering of CoSi2 on (100) Si and evaporated Si. However, at elevated temperatures (400°C< <600°C), sputtering of CoSi2 on Si undergoes two consecutive stages. During the initial stage, the thickness of the silicide layer decreases at the same rate as that of the silicide on SiO2, and is accompanied by an enrichment in Co concentration near the surface. During the second stage, the etch rate of the silicide is reduced to only one third of the rate during the initial stage.

Experimental Investigation of Particle Decontamination Efficiency in a Single-Bubble by Pool Scrubbing

2020 ◽  
Author(s):  
Kota Fujiwara ◽  
Yuki Nakamura ◽  
Kohei Yoshida ◽  
Akiko Kaneko ◽  
Yutaka Abe
Keyword(s):  
Nuclear Power ◽  
Particle Concentration ◽  
Source Term ◽  
Mechanistic Model ◽  
Particle Diameter ◽  
Fission Products ◽  
Decontamination Factor ◽  
Experimental Results ◽  
Single Bubble ◽  
Internal Particle

Abstract Nuclear power plant (NPP) safety has become a public issue since the Fukushima daiichi NPP accident. In order to evaluate the risks caused by severe accidents (SAs), it is very important to understand the on-site source term events. One of the important unsolved source term events is the decontamination efficiency of fission products (FPs) in the suppression chamber by pool scrubbing. Therefore, a mechanistic model to analyze the particle decontamination efficiency by pool scrubbing is highly regarded. Despite the demand, particle decontamination mechanism by pool scrubbing has never been understood due to the complexity of phenomena. In our experiment, we aim to develop a reliable mechanistic model to evaluate particle decontamination efficiency of pool scrubbing by conducting separate effect tests. As to obtain the fundamental process of particle decontamination from gas to liquid-phase, we focused on decontamination factor (DF) of particle from a single bubble. However, it is very difficult to calculate the initial particle concentration inside the bubble. Therefore, in our experiment, we developed a method to measure the internal particle concentration inside the bubble by combining image processing and particle measurement. By using the experimental results, we succeeded to obtain reasonable DF for glycerin particles and CsI particles as a simulant particle for FPs. From the experimental results, detailed particle decontamination efficiency for various submergence were measured. The results tend show that DF increase linearly as submergence increases which suggests that DF is constant on bubble rise region. Moreover, the fact that glycerin particle with larger particle diameter takes a higher value shows that particle diameter significantly affects DF.

scholarly journals Selected elements cations exchange in acidic medium on sorbents surface based on modified brown coal

2017 ◽  
Vol 33 (1) ◽  
pp. 139-150 ◽  
Author(s):  
Agata Stempkowska ◽  
Piotr Izak ◽  
Joanna Mastalska-Popławska
Keyword(s):  
Hydrochloric Acid ◽  
Chemical Modification ◽  
Brown Coal ◽  
Elevated Temperatures ◽  
Exchange Capacity ◽  
Distilled Water ◽  
Desorption Process ◽  
Second Stage ◽  
Before And After ◽  
Static Conditions

Abstract Studies on the sorption and desorption of selected Na+, Ca2+, Mg2+, Mn2+, Cu2+ and Cr3+ cations by materials based on modified brown coal were carried out. The chemical modification of the sorbent material consisted of grinding involving different inorganic substances and organic polymers. Samples were subjected to chemical modification at elevated temperatures for several hours. For comparative purposes, as apart from brown coal, pure humic acids are known for the highest cations exchange capacity, samples of brown coal before and after purification were also analyzed. The ion capacity was determined under static conditions, measuring the difference in the concentration of cations in the sorbent before and after sorption and then after rinsing the sorbent with distilled water (A), and after the desorption process with hydrochloric acid (B). Studies have shown that sorbents based on modified brown coal have rather significant exchange capacities in the range of 270-450 meq/100 g for the first stage and 90-200 meq/100 g for the second stage. It was also found that purified humic acid (450-200 meq/100 g) has the highest exchange capacity and modified brown coal obtained at 250°C has the lowest. The measurement of desorption showed that approximately 10% of the cations are already leached by distilled water and the residue is desorbed under the influence of 10% hydrochloric acid, but the total amount of cations is compatible with the measurement process of the second stage. The sorption affinity to various cations is different. In the case of the sorption measurements, modified sorbents show the highest sorption affinity with respect to calcium, while the unmodified raw brown coal with respect to chromium. The next stage of the measurement showed that the valence of the cation has the highest impact on the sorption affinity.

scholarly journals CALCULATION OF RADIOACTIVE SOURCE TERM RELEASE FROM FLEXBLUE NPP

2021 ◽  
Vol 23 (2) ◽  
pp. 63
Author(s):  
Muhammad Budi Setiawan ◽  
Pande Made Udiyani
Keyword(s):  
Nuclear Power ◽  
Noble Metals ◽  
Nuclear Reactor ◽  
Source Term ◽  
Reactor Core ◽  
Fission Products ◽  
Operating Conditions ◽  
Normal Operating ◽  
Small Modular Reactor ◽  
Mechanistic Approach

One of the National Research Programs (PRN) in the energy sector of the Indonesian Ministry of Research and Technology for the period of 2020-2024 is small modular reactor (SMR) nuclear power plant (NPP) assessment. The France’s Flexblue is a PWR-based SMR submerged reactor with a power of 160 MWe. The Flexblue reactor module was built on the ocean site and easily provided the supply of reactor modules, in accordance with the conditions of Indonesia as an archipelagic country. Therefore, it is necessary to know the release of fission products (source term), which is necessary for the study of the radiation safety of a nuclear reactor. This paper aims to examine the source term in normal operating conditions and abnormal normal operating conditions, as well as postulated accidents. Based on the Flexblue reactor core parameter data, the calculation of the reactor core inventory uses the ORIGEN2 software is previously evaluated. The source term calculation uses a mechanistic approach and a graded approach. The normal source term is calculated assuming the presence of impurities on the fuel plate, due to fabrication limitations. Meanwhile, the abnormal source term is postulated in the LOCA event. The core reactor inventory and source term is divided into 8 radionuclide groups which are Noble gasses group (Xe, Kr); Halogen (I); Akali Metal (Cs, Rb); Tellurium Group (Te, Sb, Sc); Barium-Strontium Group (Ba, Sr); Noble Metals (Ru, Rh, Pd, Mo, Tc, Co); Lanthanides group (La, Zr, Nd, Eu, Nb, Pm, Pr, Sm, Y, Cm, Am) and Cerium Group (Ce, Pu , Np).

Summary of Tritium Source Term Study in 10 MW High Temperature Gas-Cooled Test Reactor

2020 ◽  
Vol 76 (4) ◽  
pp. 513-525
Author(s):  
X. Liu ◽  
W. Peng ◽  
F. Xie ◽  
J. Cao ◽  
Y. Dong ◽  
...  
Keyword(s):  
High Temperature ◽  
Source Term ◽  
Term Study ◽  
Test Reactor ◽  
High Temperature Gas

Influence of Passive Autocatalytic Recombiners on Iodine Volatility: THAI Technical Scale Experiments

2008 ◽  
Author(s):  
Gerhard Poss ◽  
Teja Kanzleiter ◽  
Friedhelm Funke ◽  
Gert Langrock ◽  
Hans-Josef Allelein ◽  
...  
Keyword(s):  
Gas Flow ◽  
Source Term ◽  
Elevated Temperatures ◽  
Molecular Iodine ◽  
Operating Conditions ◽  
Severe Accident ◽  
Potential Contribution ◽  
Conversion Rates ◽  
Catalytic Material ◽  
Aerosol Parameters

Passive Autocatalytic Recombiners (PARs) in PWR-Containments remove hydrogen released in case of a severe accident with core damage by catalytic oxidation with the oxygen of the containment atmosphere. The removal of hydrogen in autocatalytic recombiners (PARs) results in temperature levels at the catalytic surfaces up to 900 °C and leads to elevated temperatures up to several hundred degrees of the gas flowing over these surfaces. Under such operating conditions suspended CsI and other iodide particles transported with the convective gas flow through PARs can be converted into volatile iodine thus influencing the iodine source term. Even low conversion rates might lead to a significant influence on the concentration of gaseous iodine in the early phase of an accident where high CsI/I2 ratios of 100:1 or even higher can be expected. In the frame of the German national THAI programme two technical-scale experiments, AER-2 and AER-5, have been performed to investigate the conversion rates CsI → I2 occurring under realistic PAR operating conditions and beyond, and the influence of PARs on CsI aerosol parameters. An original SIEMENS (now AREVA NP) type PAR has been operated under realistic thermalhydraulic conditions. CsI aerosol has been generated by evaporating ultra pure CsI in an inductive furnace and monitored in the THAI vessel, following re-condensation, by low pressure impactors and filters. Experiments with hydrogen concentrations of up to 5 vol% H2 under normal conditions and of up to 10.5 vol% H2 in a steam-inerted atmosphere have been performed. An approved and qualified sampling and detection method has been applied to determine gas borne molecular iodine concentrations. CsI → I2 conversion rates of 3% have been observed as an upper limit under realistic thermalhydraulic conditions. The results are compared to CsI → I2 conversion rates achieved in the French RECI experiments. These experiments investigated the interaction of catalytic material and metal iodides (CsI, CdI) in a lab-scale setup showing conversion rates up to 60%. However, these experiments might deviate from representative thermochemical conditions. A comparison of THAI and RECI results — as far as appropriate concerning aerosol parameters and gas temperatures — shows conversion rates in comparable dimensions. In other cases they differ significantly. The potential contribution of an operating PAR (metal iodide interaction) to the iodine source term together with the restricted knowledge from both THAI and RECI tests, means that further investigations are required.

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