11 research outputs found
Oxidation and Release of Ruthenium from White Inclusions
In this paper the laboratory test results on oxidation and release of ruthenium as a fission product element are summarised. The ruthenium appears in the nuclear fuel pellets of pressurized water reactors as one of the fission product elements during burnup. In case of severe accident when the air can contact the degraded hot fuel,
the ruthenium oxidises and its gaseous oxides, especially the RuO4, release rapidly from the pellets to the environment. Because of high radio- and chemotoxicity of ruthenium tetra-oxide further experimental study of oxidation and release is essential.
It is well known that ruthenium in the irradiated fuel UO2 fuel appears
in small metallic alloy precipitations together with fission product elements
as Mo, Rh, Pd and Tc. The precipitations are seen in the metallographic pictures as white inclusions. This separate effect study focused on the differences in the release
rate of gaseous ruthenium oxides when pure ruthenium or Mo-Ru-Rh-Pd metallic alloy is present in the simulated nuclear fuel. The oxidation and release were studied at constant reaction temperatures of 1000 or 1100 Celsius.
The tests showed that during high-temperature oxidation of the Mo-Ru-Rh-Pd alloy in air flow the release rate of gaseous ruthenium oxides is reduced to 60-80% compared to the value measured in case of oxidation of pure metallic ruthenium powder in the same thermal-hydraulic conditions.
Furthermore, if additional elements and chemical compounds representing other fission products were added in the alloy, a time delay of 30 to 60 min appeared in the release of gaseous ruthenium to the room-temperature environment.
One of the main results was that in the outlet air flow reaching the environment the partial pressure of RuO4 was far above what could be expected for room-temperature equilibrium conditions. It was pointed out that the highly volatile RuO4 can decompose in solid, non-volatile RuO2 and O2. The X-ray fluorescence analysis results showed that some ruthenium compounds deposited on the colder circuit walls of the test facility. This suggests RuO4 is not fully airstable, i.e., its stability in air can be limited in time.JRC.F.4-Nuclear design safet
Oxidation and Release of Ruthenium from Short Fuel Rods above 1500oC
The fission product ruthenium is radiotoxic and in oxidized form as ruthenium-tetroxide
(RuO4) also chemical toxic. During fuel element change or in case of a leakage in fuel storages, air flows in the containment or fuel storage. If the circulation pump fails, the fuel elements are heated-up, and at high temperatures gaseous ruthenium oxides are formed and rapidly released from the fuel. Due to the significant higher volatility of RuO4 in the Chernobyl Catastrophe the measured concentration of the Ru-isotopes in the fall-outs was comparable to those of iodine and caesium. In order to get more insight in the chemical and physical behaviour of this fission product under severe accident conditions, the Ruthenium release was studied in a series of Separate Effect Tests (RUSET). In the test short fuel rod segments were used and exposed to air and steam atmosphere at high temperatures. The experiments in air atmosphere showed, that the partial pressures of the released Ru-oxides was two orders of magnitudes lower compared to those measured in previous tests with Ru-powder diluted in a ZrO2 matrix. It was found that ruthenium was not released in steam atmosphere in
the examined temperature range. Furthermore, the temperature dependence of the deposition was detected by XRF analysis.JRC.F.4-Nuclear design safet
Experimental investigation of the late phase of spent fuel pool accidents
Experimental programmes have been carried out in order to investigate the behaviour of nuclear fuel components in high-temperature air atmosphere, which characterises the main conditions of the late phase of spent fuel pool accidents. The tests provided new data on the oxidation of zirconium cladding in different atmospheres, on the oxidation and release of ruthenium from fuel pellets and on the integral behaviour of fuel bundles. The integral test confirmed that water injection into the spent fuel storage pool is the right measure to terminate a severe accident
On the relation between isotope effects on vapour pressure and molecular structure
A comparative analysis of available experimental data of
the isotope effects on the vapour pressure of polyatomic
liquid compounds is given. As a common basis for comparison
the reduced temperature scale is used.The variations in the vapour pressure ratio with the reduced
temperature have a nearly identical shape for isotopic substitutions
of the same character in the same radicals of different
compounds or in compounds having identical structures.For some groups of compounds a linear relation ship is
found between the isotopic effects related to the same value
of the reduced temperature scale and the reciprocal square
roots of the molecular weights
Behavior of VVER Fuel Rods Tested Under Severe Accident Conditions in the CODEX Facility
The early phase of severe accidents in VVER reactors was simulated in the CODEX (COre Degradation EXperiment) facility with electrically heated fuel rod bundles. The selected test conditions and applied measurement techniques made possible the observation of some specific phenomena, such as the protective role of oxide scale during quenching of high-temperature bundles, the composition of gases produced during the oxidation of boron-carbide control rods, and the interlink between the aerosol release and the oxidation process. The general behavior of the VVER bundles did not differ significantly from that of the Western-design light water reactor bundles tested under similar high-temperature conditions, but the experiments emphasized that the application of VVER-specific material properties and models is essential for comprehensive numerical simulations.JRC.F.4-Nuclear design safet
Immunnefelometria Ă©s nagy teljesĂtmĂ©nyű folyadĂ©kkromatográfia a microalbuminuria vizsgálatában. Ăšjonnan javasolt határĂ©rtĂ©kek vizsgálata = Analysis of microalbuminuria with immunonephelometry and high performance liquid chromatography. Evaluation of new criteria
Mind a hipertĂłnia, mind a 2-es tĂpusĂş diabetes mellitus jelentĹ‘s tĂ©nyezĹ‘ a nĂ©pessĂ©g halálozásában. MindkĂ©t betegsĂ©g károsĂtja az endothelt, aminek korai jele a microalbuminuria, amelyet szűrĹ‘vizsgálatkĂ©nt tesztcsĂkkal, diagnosztikus vizsgálatkĂ©nt immunolĂłgiai alapĂş mĂłdszerekkel, illetve nagy teljesĂtmĂ©nyű folyadĂ©kkromatográfiával lehet mĂ©rni. Ez utĂłbbi segĂtsĂ©gĂ©vel az Ăşn. nem immunreaktĂv albuminforma is kimutathatĂł.
Célkitűzés:
A szerzĹ‘k cĂ©lkitűzĂ©se immunnefelometriával microalbuminuriára negatĂv, diabĂ©teszes Ă©s hipertĂłniás, illetve nem diabĂ©teszes hipertĂłniás betegek albuminĂĽrĂtĂ©sĂ©nek vizsgálata volt nagy teljesĂtmĂ©nyű folyadĂ©kkromatográfiával. Továbbá cĂ©lul tűztĂ©k ki a microalbuminuria megállapĂtásához használt jelenlegi kritĂ©riumok (albumin-kreatinin hányados: fĂ©rfiaknál ≥2,5 mg/mmol, nĹ‘knĂ©l ≥3,5 mg/mmol) Ă©s a közelmĂşltban megjelent Heart Outcomes Prevention Evaluation tanulmány által javasolt Ăşj kritĂ©riumok (nem diabĂ©teszesekben, immunolĂłgiai mĂłdszerrel ≥0,7 mg/mmol, nagy teljesĂtmĂ©nyű folyadĂ©kkromatográfiás mĂłdszerrel ≥3,1 mg/mmol, diabĂ©teszesekben immunolĂłgiai mĂłdszerrel ≥1,4 mg/mmol, nagy teljesĂtmĂ©nyű folyadĂ©kkromatográfiával ≥5,2 mg/mmol) használhatĂłságának vizsgálatát is.
MĂłdszer:
SzűrĹ‘vizsgálattal microalbuminuriára negatĂv 469 egyĂ©n vizeletĂ©nek vizsgálata törtĂ©nt meg immunnefelometriás mĂłdszerrel. Az Ăgy is negatĂvakat vizsgálták tovább nagy teljesĂtmĂ©nyű folyadĂ©kkromatográfián alapulĂł, a mĂ©retkizárásos kromatográfia elvĂ©n működĹ‘ Accumin™ Kit-tel.
Eredmények:
Nagy teljesĂtmĂ©nyű folyadĂ©kkromatográfiával átlagosan háromszor nagyobb albuminĂĽrĂtĂ©st mĂ©rtek, mint immunnefelometriával. Az intraindividuális variáciĂłs koefficiens a kĂ©t mĂłdszerrel nem kĂĽlönbözött (37 ± 31% Ă©s 40 ± 31%,
p
= 0,869; immunnefelometria Ă©s nagy teljesĂtmĂ©nyű folyadĂ©kkromatográfia; átlag ± szĂłrás). A jelenlegi albumin-kreatinin hányadoson alapulĂł kritĂ©riumokat használva, az immunolĂłgiai mĂłdszerrel negatĂv egyĂ©nek nagy teljesĂtmĂ©nyű folyadĂ©kkromatográfiával 43%-ban bizonyultak pozitĂvnak. Ha a Heart Outcomes Prevention Evaluation tanulmány Ăşj kritĂ©riumait használták, 14,5%-ra csökkent az immunnefelometriával negatĂv, nagy teljesĂtmĂ©nyű folyadĂ©kkromatográfiával pozitĂvak aránya; nagy teljesĂtmĂ©nyű folyadĂ©kkromatográfiával microalbuminuria-pozitĂvak száma elsĹ‘sorban a diabĂ©teszes Ă©s hipertĂłniás csoportban csökkent (49% Ă©s 7,5%), mĂg a nem diabĂ©teszes hipertĂłniás csoportban kevĂ©sbĂ© (37% Ă©s 26,5%). A hagyományos kritĂ©riumrendszerben logisztikus regressziĂłs vizsgálat során a legerĹ‘sebb kockázati faktornak a fĂ©rfinem bizonyult. Az immunnefelometriával microalbuminuriára negatĂv egyĂ©nek 28%-ában nagy teljesĂtmĂ©nyű folyadĂ©kkromatográfiával kimondhatĂł a microalbuminuria diagnĂłzisa a jelen szakmai szabályok szerint.
Következtetések:
Az immunolĂłgiai mĂłdszerekkel microalbuminuriára negatĂv egyĂ©nek közel harmadában nagy teljesĂtmĂ©nyű folyadĂ©kkromatográfiával kimondhatĂł a microalbuminuria diagnĂłzisa, amihez továbbra is szĂĽksĂ©ges a háromszori vizeletvizsgálat. A Heart Outcomes Prevention Evaluation tanulmány által megállapĂtott Ăşj kritĂ©riumok sem a diabĂ©teszes Ă©s hipertĂłniás betegekre, sem a nem diabĂ©teszes hipertĂłniás betegekre nem alkalmazhatĂłk jĂłl. Nem lehet figyelmen kĂvĂĽl hagyni a microalbuminuria-pozitivitás legjelentĹ‘sebb prediktorát, a nemet.
|
Introduction:
Hypertension as well as type 2 diabetes mellitus is a major factor in population mortality. Both diseases damage the endothelium, the early sign of which is microalbuminuria, which can be screened by dipstick and can be diagnosed by using immuno-based and high performance liquid chromatography methods. Using high performance liquid chromatography, the non-immunoreactive albumin can be detected as well.
Aims:
The authors aimed at the examination of albuminuria in the case of immunonephelometrically negative patients with high performance liquid chromatography, in diabetic and hypertensive and non-diabetic hypertensive populations. The authors also wanted to compare the present (albumin-creatinine ratio: male: ≥2.5 mg/mmol, female: ≥3.5 mg/mmol) and a new criteria of the Heart Outcomes Prevention Evaluation study (patients without diabetes: immunological method, ≥0.7 mg/mmol; high performance liquid chromatography, ≥3.1 mg/mmol; individuals with diabetes: immunological method, ≥1.4 mg/mmol; high performance liquid chromatography, ≥5.2 mg/mmol) of microalbuminuria.
Methods:
Examination of fresh urines of 469 microalbuminuria negative patients by dipstick were performed by immunonephelometry. Patients, who were microalbuminuria negative by immunonephelometry as well, were further analyzed by high performance liquid chromatography using the Accumin™ Kit, based on size-exclusion chromatography.
Results:
Three times higher albuminuria were found with high performance liquid chromatography than with immunonephelometry. The intraindividual coefficient of variation did not differ in the two methods (37 ± 31% vs. 40 ± 31%,
p
= 0.869; immunonephelometry vs. high performance liquid chromatography; mean ± standard deviation). Using the present criteria for microalbuminuria, 43% of immunonephelometrically negative patients proved to be microalbuminuric by high performance liquid chromatography. Using the new criteria of the Heart Outcomes Prevention Evaluation study, the rate of microalbuminuria positivity among the immunonephelometrically negative patients decreased to 14.5% by high performance liquid chromatography and the decrease in the number of microalbuminuria positive cases by high performance liquid chromatography could be observed mainly in the diabetic and hypertensive group (49% vs. 7.5%), while slighter decrease could be observed in the non-diabetic hypertensive group (37% vs. 26.5%). Applying the traditional criteria, the strongest predictor was the male gender by the logistic regression analysis. In 28% of microalbuminuria negative patients by immunonephelometry the diagnosis of microalbuminuria can be established using high performance liquid chromatography.
Conclusions:
Almost in one-third of microalbuminuria negative patients by immunonephelometry the diagnosis of microalbuminuria can be established by high performance liquid chromatography for which diagnosis three constitutive urine examinations are still needed. New criteria determined by the Heart Outcomes Prevention Evaluation study can be used neither in case of diabetic and hypertensive patients, nor in the case of non-diabetic hypertensive patients. The gender as the most important predictor of microalbuminuria cannot be ignored
Urinary ortho-tyrosine excretion in diabetes mellitus and renal failure: Evidence for hydroxyl radical production
Salt-responsive gut commensal modulates TH17 axis and disease
A Western lifestyle with high salt consumption can lead to hypertension and cardiovascular disease. High salt may additionally drive autoimmunity by inducing T helper 17 (T(H)17) cells, which can also contribute to hypertension. Induction of T(H)17 cells depends on gut microbiota; however, the effect of salt on the gut microbiome is unknown. Here we show that high salt intake affects the gut microbiome in mice, particularly by depleting Lactobacillus murinus. Consequently, treatment of mice with L. murinus prevented salt-induced aggravation of actively induced experimental autoimmune encephalomyelitis and salt-sensitive hypertension by modulating T(H)17 cells. In line with these findings, a moderate high-salt challenge in a pilot study in humans reduced intestinal survival of Lactobacillus spp., increased T(H)17 cells and increased blood pressure. Our results connect high salt intake to the gut-immune axis and highlight the gut microbiome as a potential therapeutic target to counteract salt-sensitive conditions