scholarly journals Reactions of fission products from a 252Cf source with NO and mixtures of NO and CO in an inert gas

2019 ◽  
Vol 107 (7) ◽  
pp. 555-560 ◽  
Author(s):  
Heinz W. Gäggeler ◽  
Ilya Usoltsev ◽  
Robert Eichler
Keyword(s):  
Spontaneous Fission ◽  
Fission Products ◽  
Inert Gases ◽  
Inert Gas ◽  
Efficient Production ◽  
Carbonyl Complexes ◽  
No Formation ◽  
252Cf Source ◽  
Transport Path ◽  
Accident Scenarios

Abstract Fission products recoiling from a 252Cf spontaneous fission source were stopped in various mixtures of inert gases containing CO and NO. For the elements of the transisition metal series Mo, Tc, Ru, and Rh previous observations of pure carbonyl complexes were reproduced. However, no formation of volatile mixed nitrosyl-carbonyl complexes or pure nitrosyl complexes for these elements have been observed. Instead, efficient production of volatile nitrosyl compounds for single iodine atoms, presumably nitrosyl iodide, NOI, was detected. This observation is of interest as potential transport path for iodine in nuclear accident scenarios and as a model for radiochemistry with the recently discovered heaviest halogen tennessine (Z=117).

ABSOLUTE YIELDS OF THE XENON AND KRYPTON ISOTOPES IN U238 SPONTANEOUS FISSION

1960 ◽  
Vol 38 (1) ◽  
pp. 1-9 ◽  
Author(s):  
B. G. Young ◽  
H. G. Thode
Keyword(s):  
Fission Product ◽  
Spontaneous Fission ◽  
Fission Products ◽  
Inert Gases ◽  
Geological Time ◽  
Neutron Fission ◽  
Fission Gas ◽  
Thermal Neutron Fission ◽  
Induced Fission ◽  
The Absolute

The absolute abundances of the isotopes of fission-product xenon and krypton in six uranium minerals have been determined mass spectrometrically using the isotope dilution technique. The fission products were resolved into a U238 spontaneous fission component, a U235 neutron-induced fission component, and a U238 neutron-induced fission component. Internal consistency in the analysis was achieved only when the Xe129 yield used for the U235 thermal neutron fission component was 20% lower than that reported by Purkayastha and Martin at I129. This discrepancy in the mass 129 chain yield measured at I129 and at Xe129 has not been resolved.Only one of the six minerals, Cinch Lake pitchblende, retained essentially all of its fission product inert gases throughout geological time. Inert gas losses from the remaining five minerals ranged from 20% to 75%. The absolute yields of the stable xenon and krypton fission products in U238 spontaneous fission were determined from an analysis of the inert gases from the Cinch Lake mineral. This analysis showed that 95.9% of the fission gas in this case resulted from the spontaneous fission and only 4.1% from neutron-induced fission.

Yields of rare earth fission products in the spontaneous fission of californium-252

1985 ◽  
Vol 91 (2) ◽  
pp. 291-296
Author(s):  
B. S. Tomar ◽  
H. Naik ◽  
A. Ramaswamy ◽  
Satya Prakash
Keyword(s):  
Rare Earth ◽  
Spontaneous Fission ◽  
Fission Products

Inert gas-exchange theory using an electric analogue

1964 ◽  
Vol 19 (6) ◽  
pp. 1193-1198 ◽  
Author(s):  
W. W. Mapleson
Keyword(s):  
Alveolar Ventilation ◽  
The Body ◽  
Exchange Theory ◽  
Inert Gases ◽  
Inert Gas ◽  
Respiratory Pattern ◽  
Whole Body ◽  
High Solubility ◽  
Systematic Analysis ◽  
Inhaled Anesthetics

When an inert gas of moderate or high solubility in blood is inhaled, the rate at which the alveolar concentration rises toward the inspired concentration increases as the inspired concentration is increased. The only previous systematic analysis of whole-body uptake of inert gases to allow for this effect was restricted to a single, artificial, respiratory pattern and the numerical calculations had to be made on a digital computer. This paper develops the theory for a range of respiratory patterns and shows how the computations may be made on a slightly modified form of a simple electric analogue. It is shown that the rate of saturation of the body increases less markedly with inspired concentration if the inspired alveolar ventilation, rather than the expired alveolar ventilation, is kept constant during the saturation process. Conversely, washout is more rapid with a constant inspired ventilation than with a constant expired ventilation. The theory is extended to show how the uptake of one inert gas may substantially affect the uptake of another, administered simultaneously. uptake, distribution and elimination; induction; recovery; drugs; inhaled anesthetics; nitrous oxide; diethyl ether; halothane; computers; ventilation; concentration effect; alveolar ventilation Submitted on February 13, 1964

Photolysis of ketene. I

1968 ◽  
Vol 46 (14) ◽  
pp. 2353-2360 ◽  
Author(s):  
A. N. Strachan ◽  
D. E. Thornton
Keyword(s):  
Carbon Monoxide ◽  
Quantum Yield ◽  
Triplet State ◽  
Singlet State ◽  
Inert Gases ◽  
Inert Gas ◽  
Excited Singlet State ◽  
Intersystem Crossing ◽  
Excited Singlet ◽  
Increasing Temperature

Ketene has been photolyzed at 3660 and 3130 Å both alone and in the presence of the inert gases C4F8 and SF6. The quantum yield of carbon monoxide has been determined at both wavelengths as a function of pressure and temperature. At 3660 Å the quantum yield decreases with increasing pressure but increases with increasing temperature. At 3130 Å the quantum yield with ketene alone remains 2.0 at both 37 and 100 °C at pressures up to 250 mm. At higher pressures of ketene or with added inert gas the quantum yield decreases with increasing pressure. The results are interpreted in terms of a mechanism in which intersystem crossing from the excited singlet state to the triplet state occurs at both wavelengths, and collisional deactivation of the excited singlet state by ketene is single stage at 3660 Å but multistage at 3130 Å.

scholarly journals Parameter Optimization and Sensitivity Studies of Spontaneous Fission with FREYA

2020 ◽  
Vol 239 ◽  
pp. 05003
Author(s):  
R. Vogt ◽  
J. Randrup ◽  
P. Talou ◽  
J. T. Van Dyke ◽  
L. A. Bernstein
Keyword(s):  
Spontaneous Fission ◽  
Fission Products ◽  
Event Analysis ◽  
Fission Reaction ◽  
Fission Event ◽  
Large Samples ◽  
Yield Functions ◽  
Sensitivity Studies ◽  
Average Neutron ◽  
Kinematic Information

For many years, the state of the art for simulating fission in transport codes amounted to sampling from average distributions. However, such "average" fission models have limited capabilities. Energy is not explicitly conserved and no correlations are available because all particles are emitted independently. However, in a true fission event, the emitted particles are correlated. Recently, Monte Carlo codes generating complete fission events have been developed, thus allowing the use of event-by-event analysis techniques. Such techniques are particularly useful because the complete kinematic information is available for the fission products and the emitted neutrons and photons. It is therefore possible to extract any desired observables, including correlations. The fast event-by-event fission code FREYA (Fission Reaction Event Yield Algorithm) generates large samples of complete fission events, employing only a few physics-based parameters. A recent optimization of these parameters for the isotopes in FREYA that undergo spontaneous fission is described and results are presented. The sensitivity of neutron observables in FREYA to the input yield functions is also discussed and the correlation between the average neutron multiplicity and fragment total kinetic energy is quantified.

Respiratory and inert gas exchange during high-frequency ventilation

1982 ◽  
Vol 52 (3) ◽  
pp. 683-689 ◽  
Author(s):  
H. T. Robertson ◽  
R. L. Coffey ◽  
T. A. Standaert ◽  
W. E. Truog
Keyword(s):  
Gas Exchange ◽  
High Frequency ◽  
Gas Flow ◽  
Inert Gases ◽  
Inert Gas ◽  
High Frequency Ventilation ◽  
Physiological Dead Space ◽  
Volume Ventilation ◽  
Frequency Ventilation ◽  
Carrier Gases

Pulmonary gas exchange during high-frequency low-tidal volume ventilation (HFV) (10 Hz, 4.8 ml/kg) was compared with conventional ventilation (CV) and an identical inspired fresh gas flow in pentobarbital-anesthetized dogs. Comparing respiratory and infused inert gas exchange (Wagner et al., J. Appl. Physiol. 36: 585--599, 1974) during HFV and CV, the efficiency of oxygenation was not different, but the Bohr physiological dead space ratio was greater on HFV (61.5 +/- 2.2% vs. 50.6 +/- 1.4%). However, the elimination of the most soluble inert gas (acetone) was markedly enhanced by HFV. The increased elimination of the soluble infused inert gases during HFV compared with CV may be related to the extensive intraregional gas mixing that allows the conducting airways to serve as a capacitance for the soluble inert gases. Comparing as exchange during HFV with three different density carrier gases (He, N2, and Ar), the efficiency of elimination of Co2 or the intravenously infused inert gases was greatest with He-O2. However, the alveolar-arterial partial pressure difference for O2 on He-O2 exceeded that on N2-O2 by 5.4 Torr during HFV. The finding agrees with similar observations during CV, suggesting that this aspect of gas exchange is not substantially altered by HFV.

Effects of physical properties of the breathing gas on decompression-sickness bubbles

1995 ◽  
Vol 79 (5) ◽  
pp. 1828-1836 ◽  
Author(s):  
M. E. Burkard ◽  
H. D. Van Liew
Keyword(s):  
Partition Coefficient ◽  
Physical Properties ◽  
Numerical Simulations ◽  
Bubble Growth ◽  
Decompression Sickness ◽  
Inert Gases ◽  
Inert Gas ◽  
Half Time ◽  
Bubble Density ◽  
Mathematical Relationships

To explore the relative dangers of different inert gases, we developed mathematical relationships concerned with bubble growth, using equations that separate gas properties from other variables. Predictions for saturation exposures were as follows. 1) Peak volume of a bubble is proportional to solubility in tissue when bubble density is high and to the 3/2 power of the ratio of the permeation coefficient to the partition coefficient when density is low. 2) Bubble duration is inversely proportional to the partition coefficient for the inert gas. 3). Sizes and durations of bubbles for one inert gas relative to another depend on whether the tissue is aqueous or lipid but are independent of the magnitude of the decompression and tissue half time. 4). He should give smaller bubbles than N2, except in aqueous tissue with low bubble density; our prediction correlates qualitatively with relative dangers observed with animals but seems to overestimate the safety afforded by He. Numerical simulations illustrate how nonsaturation dives are less predictable because more variables are involved.

scholarly journals The mobility of alkali ions in gases. IV. Measurements in gaseous mixtures

1941 ◽  
Vol 177 (969) ◽  
pp. 192-199 ◽  
Keyword(s):  
Water Molecule ◽  
Linear Function ◽  
Water Vapour ◽  
Gradual Increase ◽  
Simple Relation ◽  
Inert Gases ◽  
Inert Gas ◽  
Maximum Deviation ◽  
Gaseous Mixtures ◽  
Alkali Ions

The mobilities of some of the alkali ions have been measured in binary mixtures of the inert gases. Blanc’s relation that the reciprocal of the mobility is a linear function of the concentration of one of the constituents is accurately obeyed in all cases except for Li + in He-Xe mixtures, where the maximum deviation is 4%. With clustered Li + ions in mixtures of water vapour and an inert gas deviations from this simple relation are observed and increase in magnitude progressively with the density of the gas. These deviations, due to the polar nature of the water molecule, can be explained by assuming a gradual increase in the size of the clustered ion with increase in the percentage of water vapour.

THE ATTACHMENT OF INERT GASES TO POWDERS FOLLOWING (n,γ) EVENTS

1961 ◽  
Vol 39 (3) ◽  
pp. 664-674 ◽  
Author(s):  
Roger Kelly
Keyword(s):  
Neutron Flux ◽  
Gamma Rays ◽  
Solid Surface ◽  
Irradiation Time ◽  
Inert Gases ◽  
Inert Gas ◽  
Maximum Distance ◽  
Coarse Powder ◽  
High Charge ◽  
Fine Powders

It has been found that, when argon, krypton, and xenon are irradiated with neutrons in the presence of various powders, a portion of the inert-gas activity becomes "attached" to the powder. The attached activity was shown to be highly enriched, and to be distinguishable from adsorbed activity. Expressing the attachment in terms of the attachmentefficiency, A ≡ (inert-gas activity attached to target)/(total inert-gas activity), it was found that A was independent of irradiation time and neutron flux, and for fine powders was also independent of pressure between 0.7 and 700 mm. The use of a very coarse powder or no powder at all led to a decrease in A, on the basis of which it was estimated that the maximum distance from a surface that attached activity can originate is about 200 mean free paths. The following miscellaneous relations were observed to hold:[Formula: see text] (ii) AAr > AKr > AXe, (iii) Aoxide > Ametal (approximate). The results were in general consistent with a mechanism of attachment based on electrical attraction: inert-gas atoms first acquire a high charge due to vacancy cascades initiated by the conversion of capture gamma rays; they then wander about, and, upon approaching a solid surface, are accelerated electrically into it.

Collisional deactivation of singlet methylene in the photolysis of ketene

1969 ◽  
Vol 47 (18) ◽  
pp. 3345-3353 ◽  
Author(s):  
R. A. Cox ◽  
K. F. Preston
Keyword(s):  
Carbon Monoxide ◽  
Quantum Yield ◽  
Ground State ◽  
Inert Gases ◽  
Inert Gas ◽  
Quantum Yields ◽  
Electronic Relaxation ◽  
Excited Singlet ◽  
State Formula ◽  
Singlet Methylene

An investigation has been made into the effect of inert gas additions on product quantum yields for the photolysis at 2800 and 2490 Å of mixtures of ketene and oxygen and for the photolysis at 2800 Å of mixtures of ketene and carbon monoxide. Concentration ratios of O2 (or CO) to CH2CO were chosen so that the reaction of CH2(3Σg−) with CH2CO could be ignored and C2H4 formation could be attributed entirely to the reaction[Formula: see text]Quenching of the C2H4 quantum yield by inert gases was interpreted in terms of collisional deactivation of CH2(1A1) to the ground state[Formula: see text]and rate constant ratios k2/k1 have been determined for a number of gases: He (0.018), Ar (0.014), Kr (0.033), Xe (0.074), N2 (0.052), N2O (0.10), CF4 (0.047), C2F6 (0.11), and SF6 (0.045). It has been assumed that collision-induced intersystem crossover in excited singlet ketene makes an insignificant contribution to the observed quenching effects, but it has not been possible to verify this assumption experimentally. The mechanism of collision-induced electronic relaxation of singlet methylene is discussed in the light of the results.

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