Studies on oxidative radiolysis of ibuprofen in presence of potassium persulfate

International Nuclear Information System (INIS)

Paul, Jhimli; Naik, D.B.; Bhardwaj, Y.K.; Varshney, Lalit

2014-01-01

The radiolysis of ibuprofen (IBP), a model pharmaceutical compound, was studied by gamma irradiation in an aqueous solution in the presence and absence of potassium persulfate (K 2 S 2 O 8 ). The extent of mineralization was investigated by measuring the UV–visible spectra, decrease in the chemical oxygen demand (COD) and the total organic carbon (TOC) content of aqueous IBP solution at different doses. The gamma radiolysis, in the presence of K 2 S 2 O 8 , required much lesser dose compared to in the absence of K 2 S 2 O 8 for the same extent of mineralization of aqueous IBP solution. The pulse radiolysis of IBP was carried out under different radiolytic conditions to understand the mechanism of efficient mineralization of IBP during gamma radiolysis in the presence of K 2 S 2 O 8 . It was found that unlike · OH radical, SO 4 ·− radical preferentially produces benzyl type of radicals via the formation of the benzene radical cation. The results concluded that the gamma radiolysis in presence of K 2 S 2 O 8 could be one of the efficient advanced oxidation processes for degradation of pharmaceutical compounds present in the aqueous solution. - Highlights: • The radiolysis of aqueous solution of Ibuprofen (IBP) was investigated. • The COD and TOC content decreased significantly in presence of K 2 S 2 O 8 . • Pulse radiolysis studies revealed the mechanism of mineralization of IBP. • The presence of K 2 S 2 O 8 increased the efficiency of gamma radiolysis

Gamma-radiolysis of organic compounds and alpha-radiolysis of water

International Nuclear Information System (INIS)

Christensen, H.

1978-09-01

This KBS-report is a collection of five technical reports. Various radiolytic problems in connection with the disposal of high-active waste are dealt with. The English titles of the five reports are: 1) Radiolysis of fulvic acids; 2) Radiolysis of organic compounds in bentonite; 3) α-radiolysis of water during the disposal of fuel without reprocessing; 4) Radiolysis of water during the disposal of unreprocessed spent fuel. Oxidation by hydrogen peroxide; 5) Formation and decomposition of hydrogen peroxide by α-radiolysis. These reports (in Swedish) are attached as Appendices A-E. (author)

Rate constant for the H˙ + H2O → ˙OH + H2 reaction at elevated temperatures measured by pulse radiolysis.

Science.gov (United States)

Muroya, Y; Yamashita, S; Lertnaisat, P; Sanguanmith, S; Meesungnoen, J; Jay-Gerin, J-P; Katsumura, Y

2017-11-22

Maintaining the structural integrity of materials in nuclear power plants is an essential issue associated with safe operation. Hydrogen (H 2 ) addition or injection to coolants is a powerful technique that has been widely applied such that the reducing conditions in the coolant water avoid corrosion and stress corrosion cracking (SCC). Because the radiation-induced reaction of ˙OH + H 2 → H˙ + H 2 O plays a crucial role in these systems, the rate constant has been measured at operation temperatures of the reactors (285-300 °C) by pulse radiolysis, generating sufficient data for analysis. The reverse reaction H˙ + H 2 O → ˙OH + H 2 is negligibly slow at ambient temperature; however, it accelerates considerably quickly at elevated temperatures. Although the reverse reaction reduces the effectiveness of H 2 addition, reliable rate constants have not yet been measured. In this study, the rate constants have been determined in a temperature range of 250-350 °C by pulse radiolysis in an aqueous I - solution.

Radiolysis of hydrocarbons in liquid phase (Modern state of problem)

International Nuclear Information System (INIS)

Saraeva, V.V.

1986-01-01

Problems of ionizing radiation effect on hydrocarbons and hydrocarbon systems in a liquid phase are considered. Modern representations on the mechanism of hydrocarbon radiolysis are presented. Electron moderation and ion-electron pair formation, behaviour of charged particles, excited states, radical formation and their reactions are discussed. Behaviour of certain hydrocarbon classes: alkanes, cyclic hydrocarbons, olefines, aromatic hydrocarbons as well as different hydrocarbon mixtures is considered in detail. Radiation-chemical changes in organic coolants and ways of increasing radiation resistance are considered. Polyphenyl compounds are noted to be most perspective here

Gamma-radiolysis of benzosubstituted crown ethers

International Nuclear Information System (INIS)

Grigor'ev, E.I.; Nesterov, S.V.; Mikhalitsyna, O.V.; Trakhtenberg, L.I.; Myasoedova, T.G.

1992-01-01

The products of gamma-radiolysis of benzosubstituted crown ethers, which are distiguished by the size of polyether ring, and alkylsubstituted DB18C6 are studied by the methods of ESR and mass-spectrometry. A mechanism of the radiolysis of the radiolysis of the studied compounds in the solid phase is proposed. It is shown that the prinicple radiolysis process is the rupture of C-O bond resulting in the stabilization of H atoms from group -CH 2 - of polyether ring is realized with a lower probability

Radiolysis of concentrated solutions. 2. Pulse and #betta#-radiolysis studies of direct and indirect effects in lithium iodide solutions

International Nuclear Information System (INIS)

Hadjadj, A.; Julien, R.; Pucheault, J.; Ferradini, C.; Hickel, B.

1982-01-01

In the preceding study of the radiolysis of concentrated aqueous LiCl solutions, one of the hypotheses used to explain the apparent inefficacy of Cl 2- formation by the direct effect was that molecular chlorine, not detectable by spectrophotometry, could be formed during the early stages of water radiolysis. Such an hypothesis is confirmed here for pulse and #betta#-radiolysis of concentrated aqueous neutral LiI solutions. Indeed, it is shown that, 10 ns after the pulse, molecular iodine, detected as I 3- , is formed with a yield that increases with the LiI concentration. The experimental results yields values of 4.8 and 7.3 respectively for the indirect and direct effects of total oxidation G/sub I 2- / + 2G/sub I 3- /. This last high value is discussed

Study of the radiolysis of water in porous media

International Nuclear Information System (INIS)

Rotureau, P.

2004-01-01

The understanding of the production of H 2 in the radiolysis of water confined into pores of concrete is important for the disposal of radioactive waste. In order to describe the mechanisms of water radiolysis in such heterogeneous porous systems we have studied the behaviour under gamma radiation of water confined in porous silica glasses with pores going from 8 to 300 nm of diameter and meso-porous molecular sieves (MCM-41). The radiolytic yields of hydroxyl radicals, hydrated electron and dihydrogen, have been determined with respect to the pore size of materials. The increase of these radiolytic yields compared to those of free water allowed us to show a charge transfer from silica to confined water. On the other hand the kinetics of hydrated electron reactions measured by pulse radiolysis are not modified. (author) [fr

Chemical evolution studies: the radiolysis and thermal decomposition of malonic acid

International Nuclear Information System (INIS)

Cruz-Castaneda, J.; Negron-Mendoza, A.; Heredia, A.; Ramos-Bernal, S.; Villafane-Barajas, S.; Frias, D.; Colin-Garcia, M.

2015-01-01

In the context of chemical evolution a simulation of a hydrothermal vent was performed. The thermolysis and radiolysis of malonic acid in aqueous solution were studied. The thermolysis was done by heating the samples (95 deg C) and radiolysis using gamma radiation. Products were identified by gas chromatography and gas chromatography-mass spectrometry. The thermal treatment produced acetic acid and CO 2 . The radiolysis experiments yield carbon dioxide, acetic acid, and di- and tricarboxylic acids. A theoretical model of the chemical process occurring under irradiation was developed; this was able to reproduce formation of products and the consumption of malonic acid. (author)

Experimental study of nitrogen oxides in the IRT-M reactor

International Nuclear Information System (INIS)

Brazovskij, I.I.; Doroshevich, V.N.; Gvozdev, A.A.; Nesterenko, V.B.; Trubnikov, V.P.

1982-01-01

A critical review of different approaches to the radiolysis study of nitrogen oxide under mixed radiation conditions of a nuclear reactor was presented. Loop reactor piant opereted following gas-liquid cycle. It was shown in the process of long experiment in the operating conditions that irreversible radiation-thermal decomposition of the coolant increases little with temperature and pressure and radioactivity of the coolant and thermophysical equipment was moderate. Numerous kinetic experiments were conducted on the ampoule plant wherein all coolant existed in the zone of ionizing radiation effect. Initial pressure in the ampoule plant was set in the range of 0.1-16 MPa, depending on conditions of the experiment, and temperature 200-500 deg C. Dosimetry of the ampoule was carried out by the radiolysis of nitrogen monoxide. The analysis of the radiolysis products was conducted utilizing gas chromatography method, coolant vapours were removed in the process of low-temperature condensation under - 70 deg C

Picosecond pulse radiolysis studies to understand the primary processes in radiolysis

International Nuclear Information System (INIS)

Jonah, C.D.; Lewis, M.A.

1984-01-01

The use of pulse radiolysis to learn about processes which occur before the beginning of chemical times is discussed. Two examples, the distance distribution of positive and negative ions in hydrocarbons, and the state of the dry electron are discussed in detail

Picosecond pulse radiolysis studies to understand the primary processes in radiolysis

Energy Technology Data Exchange (ETDEWEB)

Jonah, C.D.; Lewis, M.A.

1984-01-01

The use of pulse radiolysis to learn about processes which occur before the beginning of chemical times is discussed. Two examples, the distance distribution of positive and negative ions in hydrocarbons, and the state of the dry electron are discussed in detail.

Primary Coolant pH Control for Soluble Boron-Free PWRs

International Nuclear Information System (INIS)

Cheon, Yang Ho; Lee, Nam Yeong; Park, Byeong Ho; Park, Seong Chan; Kim, Eun Kee

2015-01-01

These should be considered when evaluating and designing the operating pH program for nuclear power plants. This paper discusses the advanced water chemistry strategies to keep pace with the recent global trends related to pH control in the primary water system for soluble boron pressurized water reactor (PWR) plants. Finally, the objective of this work is to study primary coolant pH control for soluble boron-free PWR plants. This paper reviewed the advanced water chemistry strategies to keep pace with the recent global trends related to pH control in the primary water chemistry system for soluble boron PWR plants. The new chemistry trend for the primary coolant is towards adaption of the constant and elevated chemistry. Finally, this work studied primary coolant pH control for soluble boron-free PWR plants. The ammonia-based water chemistry related to pH control for boron-free PWR plants was discussed. The ammonia-based water chemistry is not recommended to avoid fluctuation of the pH value by ammonia radiolysis and to reduce C-14 production in reactor coolant from reaction with dissolved nitrogen. Also, the potassium-based water chemistry related to pH control for boron-free PWR plants was discussed. KOH has a potential as an alternative pH control agent for soluble boron-free PWR plants. The potassium-based water chemistry related to pH control is recommended for boron-free operation as follows

Radiolysis study of the radical-like action mechanisms of an antioxidant: Sulfarlem

International Nuclear Information System (INIS)

Ruimy-Ifrah, Pascale

1989-01-01

Sulfarlem or p-anisyldithiolthione (ADT) is a sulfured heterocyclic compound which exhibits antioxidant properties. This work presents the quantitative study of the mono-electronic exchange mechanisms involved in this action. This study has been performed by gamma radiolysis and pulse radiolysis. The gamma radiolysis of ADT aerated ethanolic solutions has shown that O 2 . and RO 2 . radicals are not reactive towards ADT. In return, ADT is an efficient scavenger of R . radicals; the rate constant of this reaction being k (ADT + R . ) = 6.7 x 10 4 mol -1 .l.s -1 . The pulse radiolysis experiments allowed the characterization of ADT reduction by the solvated electron (k (e solv - + ADT) = 2.3 x 10 10 mol -1 .l.s -1 ), the determination of the absorption spectrum of the reduced species A . (maximum wavelength = 580 nm) and the rate constant of its evolution (k (A . + A . ) = 5.7 x 10 8 mol -1 .l.s -1 ). An analogous study has been performed with ADO, an ADT oxidized derivative, which appeared to be a less efficient free radicals scavenger. (author) [fr

Study by γ radiolysis and pulsed radiolysis of the reactivity of the superoxide ion in the oxyhemoglobin-methemoglobin system

International Nuclear Information System (INIS)

Haristoy, Didier.

1976-01-01

γ radiolysis of aqueous solutions of methemoglobin (MetHb) in the presence of formate ions, shows that only 25% of the total protein is reduced in oxyhemoglobin (HbO 2 ) by superoxide ions O 2 - according to the reaction MetHb+O 2 - →HbO 2 . The result can be attributed neither to the reactions of O 2 - with HbO 2 , nor the oxidation of HbO 2 by H 2 O 2 produced in the radiolysis of water and by dismutation of O 2 - . Pulse radiolysis studies of this reaction strongly suggest the formation of a transient complex 'MetHbO 2 - ' during the reaction. In addition to the well known self-oxidation of HbO 2 , these results show the existence of an equilibrium between HbO 2 and MetHb+O 2 - . Such an equilibrium could give rise, 'in vivo' to a nearly steady concentration of superoxide ions which could initiate a reaction favoring oxidation by oxygen [fr

Gamma-radiolysis of dimethyl sulfoxide. II. Radiolysis yields and possible mechanisms

International Nuclear Information System (INIS)

Gutierrez, M. C.; Barrera, R.

1978-01-01

As result of quantitative studies on gamma-radiolysis of DMSO at a dose range of 90-850 Mrads, constant G values have been obtained for the following radiolysis compounds: G(-DMSO) - 6.7 ±0.2; G(dimethyl sulphide) - 3.4 ±0.3; G(methane) - 0,75 ± 0.04; G(dimethyl disulphide) -0.33 ±0,03; G(tri methylsulphonium methanesulphonate) - 0.26 ± 0,01; G(methyl methanethiosulphonate) - 0,25 ±0.02; G(dimethyl sulphona)-0.21±0.02; G(H 2 )-0.18±0.02; and G(propane)--0.0092±0.0007. Initial G values have been obtained for other identified compounds: Gi(ethane)-0,46; Gi(CO)-0.052; and Gi(CO 2 )-0.030. Possible mechanisms on the radiolysis process are proposed. (Author) 17 refs

Gas phase pulse radiolysis

International Nuclear Information System (INIS)

Jonah, C.D.; Andong Liu; Mulac, W.A.

1987-01-01

Gas phase pulse radiolysis, a technique which can be used to study many different phenomena in chemistry and physics, is discussed. As a source of small radicals, pulse radiolysis is important to the field of chemistry, particularly to combustion and atmospheric kinetics. The reactions of 1,3-butadiene, allene, ethylene and acetylene with OH are presented. 52 refs., 1 fig., 1 tab

Comparative design study of FR plants with various coolants. 1. Studies on Na coolant FR, Pb-Bi coolant FR, gas coolant FR

International Nuclear Information System (INIS)

Konomura, Mamoru; Shimakawa, Yoshio; Hori, Toru; Kawasaki, Nobuchika; Enuma, Yasuhiro; Kida, Masanori; Kasai, Shigeo; Ichimiya, Masakazu

2001-01-01

In Phase I of the Feasibility Studies on the Commercialized Fast Reactor (FR) Cycle System, plant designs on FR were performed with various coolants. This report describes the plant designs on FR with sodium, lead-bismuth, CO 2 gas and He gas coolants. A construction cost of 0.2 million yen/kWe was set up as a design goal. The result is as follows: The sodium reactor has a capability to obtain the goal, and lead-bismuth and gas reactors may satisfy the goal with further improvements. (author)

Radiolysis of concentrated solutions. 1. Pulse and γ radiolysis studies of direct and indirect effects in LiCl solutions

International Nuclear Information System (INIS)

Pucheault, J.; Ferradini, C.; Julien, R.; Deysine, A.; Gilles, L.; Moreau, M.

1979-01-01

This study of the radiolysis of concentrated aqueous LiCl solutions enables the relative contributions of the direct and indirect effects to be evaluated as a function of Cl - concentration and also permits an evaluation of the role of Cl - in the early stages of water radiolysis. Radicalar and molecular yields G/sub Cl 2 - /, G/sub OH/, G//sub e//sub aq/ - / + G/sub H/, G/sub H 2 O 2 /, and G/sub H 2 / are determined for all concentrations employed, and the material balance is verified. The main conclusions concerning the apparent inefficacy of the direct effect and the importance of OH scavenging in spurs are discussed

Pulse radiolysis study on aqueous solution of nicotine

International Nuclear Information System (INIS)

Wang Shilong; Mei Wang; Ni Yaming; Yao Side; Wang Wenfeng

2004-01-01

Nicotine has been studied for the first time by pulse radiolysis techniques. It has been found that hydrated electrons, hydrogen radicals and hydroxyl radicals can react with nicotine to produce anion radicals and neutral radicals, respectively, and the related rate constants have been determined. (authors)

Pulse radiolysis studies on DNA-Binding radioprotectors

International Nuclear Information System (INIS)

Anderson, R.F.

1996-01-01

Full text: Hoechst 33342 and newly-synthesised analogues exhibit radioprotective activity in cultured cells and in vivo, as described in accompanying abstracts. These minor groove binding ligands bind at discreet sites in DNA, characterised by 3 to 4 consecutive AT base pairs, and DNA sequencing studies have shown focussed radioprotection at these binding sites. There is evidence that the bound ligands also confer more 'global' protection including the intervening DNA between the binding sites. The observed focussed radioprotection could be explained by H-atom donation from the ligand to radiation-induced carbon-centred deoxyribosyl radicals, but this mechanism is unlikely to account for the global radioprotection. We now report pulse radiolysis studies on another possible mechanism, namely reduction of transient radiation-induced oxidising species on DNA by the ligand, which is consistent with the report of reduction of G + by TMPD. Oxidation of deoxyguanosine (dG) by Br 2 - , produced by radiolysis of Br- in N 2 0-saturated solutions, in the presence of Hoechst 33342 results in the appearance of a transient ligand species which is kinetically resolvable from that obtained from direct oxidation of Hoechst 33342 by Br 2 - . A plot of reaction rate versus ligand concentration indicates that the rate constant for reduction of G + is approximately 3 x 10 8 dm 3 M -1 sec -1 . Similar experiments with DNA, rather than dG, also revealed a transient species corresponding to oxidation of the ligand, but the absolute rate of oxidation was considerably slower for the DNA-bound ligand compared to that for oxidation of the free ligand by G+. These results are clearly consistent with the proposed mechanism of radioprotection by Hoechst 33342 and its analogues, moreover, pulse radiolysis may provide a very useful endpoint for screening new analogues, as a preliminary to radiobiological evaluation

Effect of ionite decomposition products on the reactor coolant pH in a boiling-water reactor

International Nuclear Information System (INIS)

Bredikhin, V.Ya.; Moskvin, L.N.

1982-01-01

The effect of products resulting from thermal radiolysis of ionites on water-chemical regime of NPP with RBMK is considered basing on investigations conducted in a boiling type experimental reactor. Data are presented on dynamics of changes in the specific electric conductivity and pH of the coolant following destruction of ion exchange groups and ionite matrix under the effect of reactor radiation. The authors draw a conclusion that radiation destruction of ionito fine disperse suspension or high-molecular soluble compounds in the reactor are, probably, one of the main reasons for variations in pH values of the coolant at NPP in non-correction water chemical regime

Pulse radiolysis studies of model membranes

International Nuclear Information System (INIS)

Heijman, M.G.J.

1984-01-01

In this thesis the influence of the structure of membranes on the processes in cell membranes were examined. Different models of the membranes were evaluated. Pulse radiolysis was used as the technique to examine the membranes. (R.B.)

Relations between oxygen and hydrogen generated by radiolysis in the systems of a CANDU 600

International Nuclear Information System (INIS)

Romano, Christian; Chocron, Mauricio; Urrutia, Guillermo

1999-01-01

The water that constitutes the coolant of the primary heat transport system, the moderator and the liquid control zones, decomposed under radiation producing as stable products oxygen, hydrogen and hydrogen peroxide throughout a complex mechanisms of radiolysis that involves ions and free radicals. These compound formed in different proportions alters the chemical control established for each system which purpose is to minimize the corrosion of the structural materials. In the present paper have been presented results of the modelling of the mentioned processes and it has been found that in the absence of a vapor phase, a relatively low concentration of hydrogen added to the water would be sufficient to control the formation of oxygen and hydrogen peroxide. The last species however, would remain in relatively high values inside a coolant fuel channel in the reactor core. (author)

Primary processes during water radiolysis

International Nuclear Information System (INIS)

Pikaev, A.K.

1980-01-01

Briefly reviewed are investigations of primary process mechanism taking place during radiolysis of water and similar systems, executed by direct and indirect methods. A conclusion is made on the important role of the water structure during radiolysis of aqueous solutions of some substances. A necessity to take account of this factor during consideration of radiolysis theoretical models is pointed out

Application of chemiluminescence to the study of alpha, beta and gamma radiolysis of water

International Nuclear Information System (INIS)

Broudic, V.; Muzeau, B.; Jegou, C.; Bonnal, M.; Gavazzi, A.; Marques, C.

2004-01-01

In the frame of the French research program on the long-term behavior of spent nuclear fuel, experiments are conducted in ATALANTE to develop and validate models of spent fuel evolution in contact with an aqueous phase. One of the mechanisms that may govern intermediate or long-term alteration of the spent fuel matrix in a repository is the oxidizing dissolution by radiolysis products of water. Leaching experiments in de-aerated media requires the analysis of hydrogen peroxide, as a major product of water radiolysis, down to 10 -8 mol.L -1 . This work presents the results obtained using the chemiluminescence reaction of iso-luminol with H 2 O 2 , catalyzed by micro-peroxidase. Depending on the samples used, different types of radiolytic processes were studied: α radiolysis of water when leaching UO 2 pellets doped with alpha emitters, or γ radiolysis of water when leaching the same samples or spent fuel in a gamma field. Influences of operating conditions on the analytical results are discussed. (authors)

Studies on radiolysis of amino acids, (3)

International Nuclear Information System (INIS)

Oku, Tadatake

1978-01-01

For the purpose of investigating the radiolysis of amino acids and the safeness to radiation, the radiolytic mechanism and radio-sensitivity of sulfur-containing amino acids in aqueous solution in the presence of air or in the atmosphere of nitrogen were studied. Aqueous solutions of L-methionine, cysteine (both 1mM) and L-cystine (0.3mM) were irradiated with γ-ray of 60 Co at the dose of 4.2 - 2,640 x 10 3 rad. The amino acids and the radiolytic products were determined with an amino acid analyzer. The volatile sulfur compounds formed from γ-irradiated methionine were estimated by a flame photometric detector-gas chromatograph. From the results obtained, G values of the radiolysis of sulfur-containing amino acids and the products were calculated, and the radiolytic mechanisms of methionine, cysteine and cystine were proposed. The radio-sensitivity of sulfur-containing amino acids was shown as follows: cysteine (C3-SH) > methionine (C5, -SCH 3 ) > cystine (C 6 , -S-S-). Off-flavor development from γ-irradiated methionine when oxidizing agent was added was less than that when reducing agent was added. (Kobatake, H.)

Radiolysis studies of uranyl nitrate solution in nitric acid medium

International Nuclear Information System (INIS)

Siri, Sandra; Mondino, Angel V.

2005-01-01

The radiolysis of acidic uranyl nitrate solutions was investigated using Co-60 gamma radiation. Hydrogen peroxide was determined as a function of increasing dose. The UV-vis absorption spectra of the irradiated solutions were measured and the spectral changes were analyzed. The increasing dose increases the absorbance intensities, possibly by an increment in nitrate concentration produced by radiolysis, which can originate the formation of different uranyl complexes in solution. (author)

Study of polysilane mainchain electronic structure by picosecond pulse radiolysis

International Nuclear Information System (INIS)

Habara, H.; Saeki, A.; Kunimi, Y.; Seki, S.; Kozawa, T.; Yoshida, Y.; Tagawa, S.

2000-01-01

The electronic structure of a charged polysilane molecle is studied. The transient absorption spectroscopy was carried out for charged radicals of poly (methylphenylsilane): PMPS by pico-second and nanosecond pulse radiolysis technique. It was observed that the peak of the transient absorption spectra shifted to longer wavelength region within a few nsec, and an increase was observed in the optical density at 370 nm, which had been already assigned to the radical anions of PMPS. It is ascribed to inter-segment electron transfer (intra-molecular transfer) through polymer chain. The nanosecond pulse radiolysis experiments gave similar kinetic traces in near-UV and IR region. This suggests the presence of an interband level, that is, a polaron level occupied by an excess electron or a hole. (author)

Oxidation of ortho- and para-aminobenzoic acid. A pulse radiolysis- and gamma radiolysis study

International Nuclear Information System (INIS)

Solar, Sonja; Getoff, Nikola; Zona, Robert; Solar, Wolfgang

2011-01-01

The oxidation of anthranilic acid (ortho-aminobenzoic acid, ANA) and para-aminobenzoic acid (PABA) by · OH, N 3 · and O ·- in basic solution was studied by pulse radiolysis. The kinetic and spectroscopic characteristics of the intermediate transients were determined. For ANA the site attack of the OH radicals was established to be ∼50% on the -NH 2 moiety and ∼50% on the aromatic ring with an overall rate constant k( · OH+ANA)=(5.5x10 9 ) dm 3 mol -1 s -1 . The rate constant of PABA was k( · OH+PABA)=8x10 9 dm 3 mol -1 s -1 . The OH-adducts of both compounds showed a first order decay of 0.8x10 5 and 1.2x10 5 s -1 , respectively, whereby the corresponding anilino-radicals were formed. The rate constant of ANA with solvated electrons was k(e - aq +ANA)=2.9x10 9 dm 3 mol -1 s -1 . The radiation induced decomposition of both substrates was studied by gamma radiolysis as a function of the absorbed dose. They exhibited a distinct radiation resistance, the initial degradation yields were ∼0.16 μmol J -1 , i.e. only 28% of the · OH radicals contributed to their decomposition. The hydroxylation process was of minor importance, the yield of hydroxylated aminobenzoic acids was≤0.01 μmol J -1 .

The effects of water radiolysis on the corrosion and stress corrosion behavior of type 316 stainless steel in pure water

International Nuclear Information System (INIS)

Wyllie, W.E. II; Duquette, D.J.; Steiner, D.

1994-11-01

In the ITER Conceptual Design Activity, water will be used as coolant for the major reactor components, which will be made of solution-annealed 316 SS. A concern is that the radiolysis products may increase the stress corrosion cracking (SCC) susceptibility of 316 SS. The corrosion and stress corrosion of 316 SS was observed under irradiated and nonirradiated conditions. Gamma irradiation produced a 100 mV potential shift in the active direction, probably from the polarizing effect of reducing radiolysis products. The irradiation also resulted in nearly an order of magnitude increase in the passive current density of 316 SS, probably from increased surface reaction rates involving radiolysis products as well as increased corrosion rates; however the latter was considered insignificant. Computer simulations of pure water radiolysis at 50, 90, and 130 C and dose rates of 10 18 -10 24 were performed; effects of hydrogen, argon, and argon + 20% oxygen deaeration were also studied. Slow strain rate suggest that annealed and sensitized 316 SS was not suscepible to SCC in hydrogen- or argon-deaerated water at 50 C. Modeling of irradiated water chemistry was performed. Open circuit potential of senstizied and annealed 316 SS had a shift of 800 mV in the noble (positive) direction. Steady-state potentials of -0.180 V for sensitized 316 SS wire and -0.096 V vs Hg/HgSO 4 for annealed 316 SS wire were independent of oxygen presence. The -0.180 V shift is likely to promote SCC

Electrons in water radiolysis

International Nuclear Information System (INIS)

Laverne, J.A.; Pimblott, S.M.

2006-01-01

The hydrated electron is the main reducing species produced in the radiolysis of water. Many studies have examined its reactivity using pulsed radiolysis techniques and competition kinetics. Data bases list hundreds of rate coefficients for reaction of the hydrated electron with substances ranging from inorganic ions like nitrate to biopolymers like DNA. Although the chemistry of the hydrated electron is often examined, its mechanism of formation and variation in yield are considerable less known, especially under extreme conditions such as in high temperature water or with heavy ion radiolysis. This work will examine various aspects of the radiation chemistry of the hydrated electron beginning with the generation of secondary electrons in primary energy loss events during the passage of ionizing radiation to the radiolytic yields of the hydrated electron produced by different types of radiation. Ion radiation is a 'white light source.' Energy losses range from the minimum excitation energy of the medium up to the kinematic maximum determined by the collision parameters. However, certain energy loss events are more probable than others. The dipole oscillator strength distributions of media essentially give the probability of energy loss events in collisions with no momentum transfer. Dipole oscillator distributions have been constructed from experimental data for a wide variety of materials including all the phases of water. Calculations using cross sections based on dipole oscillator distributions show that the most probable energy loss event in water is only about 20 eV with an average value closer to 60 eV. The preponderance of energy loss events of less than 100 eV means that many low energy electrons are formed by the passage of a single ion. Low energy electrons have short mean free paths and they remain in the vicinity of the primary energy loss events. The spatial distribution of these low energy electrons defines the radial track structure of the incident

Study of the radiolysis of tetracycline hidrochloride in aerated aqueous solutions

International Nuclear Information System (INIS)

Guedes, S.M.L.; Vasconcellos, M.B.A.

1983-01-01

The radiolysis of tetracycline hydrochloride (TC) was studied in neutral, acid and alkaline aerated solutions, by electron spin resonance spectroscopy at 77K. The paramagnetic species observed are: H.; OH.; HO 2 .; e - trapped and impurity radical. The reaction mechanism shows that the solute reacts with the solvent before the radiolysis and produces H + ions, as a consequence of the ionization of tricarbonylmethane group. The H + ions react with the e - from the radiolysis of water and produce HO 2 in the presence of O 2 . The interaction of TC with the alkaline solvent favours the interaction between gamma rays and solute. The products formed in the interaction of solute with the solvent before the radiolysis, as a consenquence of the ionization of TC, according to the pH of the solution, are of fundamental importance in the interaction of gamma rays with the solute. A crude estimate of the average distance that the e - is able to travel through solvent molecules before its capture by the solute was obtained in these 0.1N, 0.5N and 1.0N NaOH aqueous solutions. Until [TC] - travels more in solutions that contain less [NaOH]. In higher [TC] the e - travels through 680 solvent molecules. In order to explain the selective capture of the e3- by solute molecules, a simple model is suggested based on the existence of channel walls of solvent molecules where the electrical atraction betwwed Na + and e - influences the collision frequency and the energy loss. (Author) [pt

Some mechanisms which may reduce radiolysis

Energy Technology Data Exchange (ETDEWEB)

Neretnieks, I; Faghihi, M. [Royal Inst. of Tech., Stockholm (Sweden). Dept. of Chemical Engineering

1991-08-01

In this report two mechanisms which may considerably decrease the rate of radiolysis are studied. The first main effect is that capillary forces in the very fine pores of the bentonite which surround the canisters do not permit the release of water if there is a gas over pressure inside the canister. As long as there is gas inside the canister the gap will partly be gas filled and the alpha-particles will have less water to radiolyze. Because some hydrogen will be dissolved and will escape by diffusion, a rate of radiolysis will be maintained which balances the rate of diffusion. This in turn will be influenced by the geometry of the diffusion path. The size of the hole in the copper canister seems to be one of the critical items which determine the escape of the hydrogen and thus the rate of radiolysis. The other main effect which will reduce the radiolysis is the accumulation of the corrosion products in the gap. This reduces the water content in the gap. Consequently there will be less water which can be radiolyzed. The presence of corrosion products which have a higher density than water will also consume the energy of the alpha-particles faster. Both effects seem to, independently, have a potential of reducing the rate of radiolysis by a few order of magnitude.

Some mechanisms which may reduce radiolysis

International Nuclear Information System (INIS)

Neretnieks, I; Faghihi, M.

1991-08-01

In this report two mechanisms which may considerably decrease the rate of radiolysis are studied. The first main effect is that capillary forces in the very fine pores of the bentonite which surround the canisters do not permit the release of water if there is a gas over pressure inside the canister. As long as there is gas inside the canister the gap will partly be gas filled and the alpha-particles will have less water to radiolyze. Because some hydrogen will be dissolved and will escape by diffusion, a rate of radiolysis will be maintained which balances the rate of diffusion. This in turn will be influenced by the geometry of the diffusion path. The size of the hole in the copper canister seems to be one of the critical items which determine the escape of the hydrogen and thus the rate of radiolysis. The other main effect which will reduce the radiolysis is the accumulation of the corrosion products in the gap. This reduces the water content in the gap. Consequently there will be less water which can be radiolyzed. The presence of corrosion products which have a higher density than water will also consume the energy of the alpha-particles faster. Both effects seem to, independently, have a potential of reducing the rate of radiolysis by a few order of magnitude

High Doses Gamma Radiolysis of PVC: Mechanisms of Degradation

International Nuclear Information System (INIS)

Colombani, J.

2006-01-01

PVC radiolysis leads to the formation of various degradation products: radicals, gas, oxidized products or polyenes. In order to predict the formation of the degradation products with regard to irradiation and ageing parameters, it is important to improve the understanding of the radiolysis mechanisms of PVC. Thus, we used several analytical techniques (Electron Spin Resonance, Fourier Transform Infrared spectroscopy, Nuclear Magnetic Resonance, Size Exclusion Chromatography) to get information on PVC samples irradiated at high doses (up to 4MGy) under different conditions. Gamma irradiation induces the formation of various radicals into PVC. Older studies were generally focused on the effect of low dose and/or low temperature irradiations on PVC. We present here ESR signals of PVC irradiated at high doses and at room temperature. We show that peroxyl radicals are producted by radiolysis under aerobe conditions and that polyenyl radicals are formed under anaerobe conditions. PVC radiolysis induces gas production and especially hydrogen chloride. Production of hydrogen chloride is well known until 1 MGy. We have studied by FTIR, the evolution of the quantity of HCl produced until 4 MGy. We show that higher irradiation dose leads to the lower radiolytic yield of HCl (G(HCl)). Moreover, G(HCl) obtained in aerobe conditions is about fourfold as great as G(HCl) observed in anaerobe radiolysis. Propagation and termination reactions induce degradation products: polyene sequences and crosslinking reactions are observed under anaerobe conditions; oxidized products with addition of chain scissions are formed under aerobe conditions. Although the literature about PVC radiolysis is rich, the main reacting pathways are not well established. Moreover the high doses studies are almost non-existent. We show by FTIR that aerobe radiolysis induces formation of ketons and acids. NMR experiments confirme these results but also focuse on small acids formed (with 2, 3 or 4 carbons). The

Current state of knowledge in radiolysis effects on spent fuel corrosion

International Nuclear Information System (INIS)

Christensen, H.; Sunder, S.

1998-09-01

Literature data on the effect of water radiolysis products on spent fuel oxidation and dissolution have been reviewed. Effects of γ-radiolysis, α-radiolysis and dissolved O 2 or H 2 O 2 in unirradiated solutions have been discussed separately. Also the effect of carbonate in γ-irradiated solutions and radiolysis effects on leaching of spent fuels have been reviewed. In addition a radiolysis model for calculation of corrosion rates of UO 2 , presented previously, has been discussed. The model has been shown to give a good agreement between calculated and measured corrosion rates in the case of γ-radiolysis and in unirradiated solutions of dissolved oxygen or hydrogen peroxide. The model has failed to predict the results of α-radiolysis. In a recent study it was shown that the model gave a good agreement with measured corrosion rates of spent fuel exposed in deionized water

Radiolysis of dilute aqueous solutions of cesium iodide

International Nuclear Information System (INIS)

Gorbovitskaya, T.I.; Galinkin, D.L.; Kants, L.K.; Tiliks, Yu.E.; Kotelkin, I.M.; Luzanova, L.M.

1993-01-01

Study of physical-chemical processes in the NPP containment by severe accident is carried out. Radiolysis of reactor cooling water containing iodine and cesium radionuclides penetrated therein in the course of accident is considered as of such processes. Role of ionizing radiation in the process of formation and release of ecologically hazardous volatile forms of radioiodine from reactor water into environment is studied. Experiments on radiolysis of CsI diluted water solutions are carried out. The data obtained were used for clarification of radiolysis mechanism for iodine-containing water system, enabling forecast of iodine behaviour in the course of the accident. 5 refs., 4 figs., 1 tab

Radiolysis of other organic compounds

International Nuclear Information System (INIS)

Pikaev, A.K.

1986-01-01

Peculiarities of radiolysis of organic halogen, phosphorus, sulfur and nitrogen (including amines, amides, nitriles et al.) compounds in liquid phase are discussed. Intermediate and stable finish products of radiolysis of the given compounds, properties and radiochemical yields of these products are considered

Current state of knowledge of water radiolysis effects on spent nuclear fuel corrosion

International Nuclear Information System (INIS)

Christensen, H.; Sunder, S.

2000-07-01

Literature data on the effect of water radiolysis products on spent-fuel oxidation and dissolution are reviewed. Effects of gamma radiolysis, alpha radiolysis, and dissolved O 2 or H 2 O 2 in unirradiated solutions are discussed separately. Also, the effect of carbonate in gamma-irradiated solutions and radiolysis effects on leaching of spent fuel are reviewed. In addition, a kinetic model for calculating the corrosion rates of UO 2 in solutions undergoing radiolysis is discussed. The model gives good agreement between calculated and measured corrosion rates in the case of gamma radiolysis and in unirradiated solutions containing dissolved oxygen or hydrogen peroxide. However, the model fails to predict the results of alpha radiolysis. In a recent study , it was shown that the model gave good agreement with measured corrosion rates of spent fuel exposed in deionized water. The applications of radiolysis studies for geologic disposal of used nuclear fuel are discussed. (author)

Study on the gamma radiolysis of poly (vinyl chloride). Application to the study on degradation by irradiation and leaching of industrial PVC

International Nuclear Information System (INIS)

Colombani, J.

2006-01-01

The works presented in this memory enter in the context of the management of plastic nuclear waste. This study was carried out on pure PVC and industrial PVC (formulated polymer). The radiolysis at high doses (up to 4 MGy) of pure PVC in anaerobic condition involves the formation of polyenyl radicals, polyenic sequences, hydrogen chloride and reactions of crosslinking. In aerobic condition, the radiolysis at high doses of pure PVC generates the formation of peroxyl radicals, hydrogen chloride, acid water, carboxylic acids, saturated or conjugated ketones and phenomena of scission. The production of HCl generated by irradiation of industrial PVC was carried out up to 40 MGy. The HCl formed by radiolysis is completely trapped by the calcic loads contained in industrial PVC and by the water produced by these reactions of trapping. A qualitative study on the formation of the products of radiolysis highlighted that the mechanisms of radiolysis of industrial PVC are different from those of pure PVC. This difference is due to the presence of additives belonging to the formulation of industrial PVC. The irradiation of plasticizers such as phthalic esters could induce the formation of radicals being able to react, by reaction of grafting, with the macro-radicals of PVC or with the polyenic sequences formed by radiolysis of PVC macromolecules. The results of leaching experiments tend to confirm this type of mechanism. (author)

Application of damage function analysis to reactor coolant circuits

International Nuclear Information System (INIS)

MacDonald, D.D.

2002-01-01

The application of deterministic models for simulating stress corrosion cracking phenomena in Boiling Water Reactor primary coolant circuits is described. The first generation code, DAMAGE-PREDICTOR, has been used to model the radiolysis of the coolant, to estimate the electrochemical corrosion potential (ECP), and to calculate the crack growth rate (CGR) at fixed state points during reactor operation in about a dozen plants worldwide. This code has been validated in ''double-blind'' comparisons between the calculated and measured hydrogen concentration, oxygen concentration, and ECP in the recirculation system of the Leibstadt BWR in Switzerland, as well as through less formal comparisons with data from other plants. Second generation codes have now been developed, including REMAIN for simulating BWRs with internal coolant pumps and the ALERT series for modeling reactors with external pumps. One of this series, ALERT, yields the integrated damage function (IDF), which is the crack length versus time, on a component-by-component basis for a specified future operating scenario. This code therefore allows one to explore proposed future operating protocols, with the objective of identifying those that are most cost-effective and which minimizes the risk of failure of components in the coolant circuit by stress corrosion cracking. The application of this code is illustrated by exploring the benefits of partial hydrogen water chemistry (HWC) for an actual reactor, in which hydrogen is added to the feedwater over only limited periods during operation. The simulations show that the benefits, in terms of reduction in the IDFs for various components, are sensitive to when HWC was initiated in the plant life and to the length of time over which it is applied. (author)

Application of damage function analysis to reactor coolant circuits

Energy Technology Data Exchange (ETDEWEB)

MacDonald, D.D. [Center for Electrochemical Science and Technology, Pennsylvania State Univ., University Park, PA (United States)

2002-07-01

The application of deterministic models for simulating stress corrosion cracking phenomena in Boiling Water Reactor primary coolant circuits is described. The first generation code, DAMAGE-PREDICTOR, has been used to model the radiolysis of the coolant, to estimate the electrochemical corrosion potential (ECP), and to calculate the crack growth rate (CGR) at fixed state points during reactor operation in about a dozen plants worldwide. This code has been validated in ''double-blind'' comparisons between the calculated and measured hydrogen concentration, oxygen concentration, and ECP in the recirculation system of the Leibstadt BWR in Switzerland, as well as through less formal comparisons with data from other plants. Second generation codes have now been developed, including REMAIN for simulating BWRs with internal coolant pumps and the ALERT series for modeling reactors with external pumps. One of this series, ALERT, yields the integrated damage function (IDF), which is the crack length versus time, on a component-by-component basis for a specified future operating scenario. This code therefore allows one to explore proposed future operating protocols, with the objective of identifying those that are most cost-effective and which minimizes the risk of failure of components in the coolant circuit by stress corrosion cracking. The application of this code is illustrated by exploring the benefits of partial hydrogen water chemistry (HWC) for an actual reactor, in which hydrogen is added to the feedwater over only limited periods during operation. The simulations show that the benefits, in terms of reduction in the IDFs for various components, are sensitive to when HWC was initiated in the plant life and to the length of time over which it is applied. (author)

Study of the effect of water radiolysis on zirconolite dissolution

International Nuclear Information System (INIS)

Tribet, M.

2007-09-01

Zirconolite is one of the matrices foreseen for the confinement of minor actinides in case of deep geological disposal. Indeed, zirconolite (general formula: CaZr x Ti 3-x O 7 (0.8 ≤ x ≤ 1.37)) is able to incorporate rare earth elements and actinides by substitution in calcium and zirconium sites and, moreover, its chemical durability into water is well known. However, in case of deep geological disposal, after a long period, water can reach the confinement matrix and can be radiolysed at the moment of the radionuclide alpha decays. In this work we have thus studied the effects of water radiolysis induced by charged particles (alphas or protons) on the dissolution of a synthetic sintered zirconolite. The formula of this zirconolite is Ca 0,8 Nd 0,2 ZrTi 1,8 Al 0,2 O 7 where Nd simulates the presence of trivalent and tetravalent actinides. We performed the irradiations with external ion beams in two distinct geometries where the fluences ranged from 10 15 to 10 16 ions.cm -2 . In the first geometry the beam stops into water before the surface/water interface. In the second one the beam gets through the sample before stopping at the surface/water interface. The use of these different configurations allows to study the respective influence of parameters such as sample irradiation, Linear Energy Transfer at the surface/water interface or total deposited energy. The irradiations were performed on both crystalline and amorphous zirconolites in pure water or with complexing species such as F - . The sample dissolution has been monitored through the release of cations. The radiolytic production of H 2 O 2 has also been measured. Our results show that the water radiolysis has an effect on the preferential release of Zr, Ti and Nd: for these elements, releases are one or two order of magnitude higher than releases out of radiolysis. Such preferential releases occur whatever the temperature (20 or 50 C), the surface state (crystalline or amorphous) and the experimental

Radiolysis of anthraquinone dyes in aqueous solutions

International Nuclear Information System (INIS)

Vysotskaya, N.A.; Bortun, L.N.; Ogurtsov, N.A.; Migdalovich, E.A.; Revina, A.A.; Volodko, V.V.; AN SSSR, Moscow. Inst. Ehlektrokhimii)

1986-01-01

The commercial anthraquinone dyes (Dark Blue, Light Blue, Green) in aqueous solutions were shown to be decoloured and degrade under the action of ionizing radiation. The degree of decolouration and degradation of aromatic rings was found to increase in presence of oxygen. Hydroxyl radicals were shown to play the key role in the degradation of the dyes under irradiation. The radiolysis intermediate products were studied using the pulse radiolysis technique. (author)

Hole transfer in DNA studied by pulse radiolysis

International Nuclear Information System (INIS)

Majima, T.; Kawai, K.; Takada, T.

2003-01-01

Attention has been paid to charge transfer in DNA with respect to oxidation damage of DNA and nano bio-devices such as DNA molecular wire. We report hole transfer in DNA during pulse radiolysis of molecule-conjugated DNA (M-DNA). Direct measurement of the charge transfer in DNA has never been reported due to the low extinction coefficient of nucleobase radical ions and to difficult definition of nucleobases. We have used M-DNA in which M radical cation has enough extinction coefficient and distinct absorption. Radical cation was generated in M-DNA during pulse radiolysis in water, and hole transfer through DNA was monitored by time-resolved transient absorption spectra of the radical cations. Hole was generated in Py-DNA by pulse radiolysis in water. Hole transfer to Py through DNA was monitored by transient absorption of Py'+ at 465 nm. The hole hopping rate (k) from G-region to Py was determined to be 104 s-1 which decreased with intervening A-T base-pairs between Py and G-region. We suppose that G(-H+)-radical and C(+H+) basepair can alive in DNA more than 100 us and that this long lifetime is responsible to the long-distance hole transfer. The dependence of k against the distance between the G-region and Py led to the slope of 0.3 Angstroms-1 which is due to multi-step k with the smaller distance dependence. On the other hand, beta = 0.6 Angstroms-1 was found for the single-step k in DNA. On the basis of pulse radiolytic studied on various molecule-conjugated DNA, we found that hole transfer between two chromophores (A and B)-conjugated DNA increased with decreasing the distance between A and B and was accelerated slightly with increasing the number of Gs of the bridge between A and B, and that k was modulated by the bridged base sequences. We also found that weak distance dependent hole transfer in DNA by adenine hopping mechanism

The application of radiolysis and analysis of influencing factors

International Nuclear Information System (INIS)

Xie Fang; Ha Yiming; Wang Feng

2008-01-01

As a branch of radiation technology, radiolysis technology has been developing in recent years. The update research and application of radiolysis is briefly reviewed. The radiolysis in reducing veterinary drug residues in food, processing plant sources products and environmental management are summaried. The influencing factors or the mechanism and radiolysis products are reviewed. (authors)

A pulse radiolysis study of the formation and reactions of reduced metal EDTA complexes

International Nuclear Information System (INIS)

Buitenhuis, R.

1977-01-01

The construction of a computerized pulse radiolysis system with available means appropriate for the wavelength interval between 300 and 1000 nm is described. The investigation of the radiolysis of aqueous solutions of EDTA complexes in the presence of alcohols is discussed

Picosecond pulse radiolysis study of primary reactions in solutions

International Nuclear Information System (INIS)

El-Omar, Abdel Karim

2013-01-01

Following the discovery of ionizing radiations and their chemical effects, it was important to study and comprehend the formation mechanisms of short lived free radicals and molecular products. In order to perform such studies, researchers and research groups worked on developing tools allowing both formation and detection of those species at short time scales. Nowadays, pulse radiolysis imposed itself as a fundamental and efficient tool allowing scientists to probe chemical effects as well as reaction mechanisms in studied media. The Laboratoire de Chimie Physique d'Orsay 'LCP' is an interdisciplinary laboratory hosting the platform of fast kinetics known as 'ELYSE'. Due to its femtosecond laser and its picosecond electron accelerator, we have the possibility to study chemical effects of ionizing radiations interaction with media at ultrashort times up to ∼5 ps.Knowing that we are interested in primary reactions induced in aqueous media by ionizing radiations, ELYSE represents the essential tool in performing our studies. The obtained results concern:- First direct determination of hydroxyl radical 'HO*' radiolytic yield as function of time at picosecond time scale;- Direct effect of ionizing radiation in highly concentrated aqueous solutions as well as investigation of the ultrafast electron transfer reaction between solute molecules and positive holes 'H 2 O*+' formed upon water radiolysis;- Study at room temperature of electron transfer reaction between solvated electron (electron donor) and organic solutes (electron acceptors) en viscous medium;- Study at room temperature of electron's solvation dynamics in ethylene glycol and 2-propanol. (author)

Reactivity of OH radicals with chlorobenzoic acids-A pulse radiolysis and steady-state radiolysis study

DEFF Research Database (Denmark)

Zona, Robert; Solar, Sonja; Getoff, Nikola

2010-01-01

The reactions of OH radicals with 2-, 3-, 4-chlorobenzoic acids (ClBzA) and chlorobenzene (ClBz), k(OH+substrates)=(4.5−6.2)×109 dm3 mol−1 s−1, have been studied by pulse radiolysis in N2O saturated solutions. The absorption maxima of the OH-adducts were in the range of 320−340 nm. Their decay wa...... to degradation. The order for the efficiency of dehalogenation was 4->2->3-ClBzA. Several primary radiolytic products could be detected by HPLC. To evaluate the toxicity of final products a bacterial bioluminescence test was carried out....

Electron paramagnetic resonance study of radicals formed by radiolysis at 77 K of nitroalkanes and of their solutions in organic glasses. Chromatography analysis of radiolysis products of nitromethane in ethanol solution in a vitreous medium

International Nuclear Information System (INIS)

Rosilio, C.

1969-01-01

With a view to explaining the formation of the final products resulting from the photolysis and the radiolysis of nitro-alkanes, we have attempted to identify the paramagnetic species formed as intermediates during the radiolysis. Our work has covered the structure and the reactivity of the radicals formed by 7 irradiation of the nitrogen containing derivatives at 77 K, and on the mechanism of formation and of disappearance of these radicals in the various matrices used. The radicals resulting from the removal of a hydrogen atom in the α position of the NO 2 group, and the radicals resulting from addition reactions on the nitrogen group characterized by an unpaired electron on the nitrogen have been identified, either during the radiolysis of pure nitroalkanes, or during the radiolysis of nitro-alkanes in solution in organic glasses at 77 K. A study has been made of the conformation and the movements of radicals in the matrices, and the mechanism of formation of the observed radicals produced generally by the capture by the nitro-alkanes of primary radiolysis species. The nitro-alkanes in ethanol solution can behave as traps both for electrons and for free radicals. The study of the radiolysis of nitro-alkanes in solution in a polar ethanol glass has been completed with chemical analyses on the final radiolysis products; it has been possible to deduce the capture efficiency of trapped electrons and of free radicals by nitro-alkanes in ethanol. For this we have determined the radio-chemical yields of hydrogen, acetaldehyde and glycol as a function of the capture agent concentration, for the nitro-methane-ethanol system. A mechanism for the disappearance of the observed radicals is proposed. (author) [fr

Study of growth mechanism of conducting polymers by pulse radiolysis

International Nuclear Information System (INIS)

Coletta, Cecilia

2016-01-01

Today conductive polymers have many applications in several devices. For these reasons they have received much attention in recent years. Despite intensive research, the mechanism of conducting polymers growth is still poorly understood and the methods of polymerization are limited to two principal ways: chemical and electrochemical synthesis. On the other hand, the complex properties of polymers can be controlled only if a good knowledge of polymerization process is acquired. In this case, it is possible to control the process during the synthesis (functionalization, hydrophilicity, chain length, doping level), and consequently to improve the conductive properties of the synthesized polymers. Water radiolysis represents an easy and efficient method of synthesis comparing to chemical and electrochemical polymerization routes. It enables the polymerization under soft conditions: ambient temperature and pressure, without any external dopant. Among all conductive polymers, poly(3, 4-ethylenedioxy-thiophene) (PEDOT, a derivative of poly-thiophene) and poly-Pyrrole (PPy) have gained some large scale applications for their chemical and physical proprieties. The aim of the present work was the synthesis of PEDOT and PPy in aqueous solution and the study of their growth mechanism by pulsed radiolysis. Thanks to the electron accelerator ELYSE, the use of pulsed radiolysis coupled with time-resolved absorption spectroscopy allowed to study the kinetics of polymerization. The first transient species involved in the mechanism were identified by time resolved spectroscopy and the rate constants were determined. First, the reaction of hydroxyl radicals onto EDOT and Py monomers was studied, as well as the corresponding radiation induced polymerization. Then, the study was transposed to others oxidizing radicals such as CO3 .- , N 3 . and SO 4 .- at different pHs. This approach allowed to check and to highlight the influence of oxidizing species onto the first transient species

Pulse radiolysis in model studies toward radiation processing

Energy Technology Data Exchange (ETDEWEB)

Sonntag, C Von; Bothe, E; Ulanski, P; Deeble, D J [Max-Planck-Institut fuer Strahlenchemie, Muelheim an der Ruhr (Germany)

1995-10-01

Using the pulse radiolysis technique, the OH-radical-induced reactions of poly(vinyl alcohol) PVAL, poly(acrylic acid) PAA, poly(methyacrylic acid) PMA, and hyaluronic acid have been investigated in dilute aqueos solution. The reactions of the free-radical intermediates were followed by UV-spectroscopy and low-angle laser light-scattering; the scission of the charged polymers was also monitored by conductometry. For more detailed product studies, model systems such as 2,4-dihydroxypentane (for PVAL) and 2,4-dimethyl glutaric acid (for PAA) was also investigated. (author).

Study of the radiolysis of some simple alcohols

International Nuclear Information System (INIS)

Roux, Jean-Claude

1974-01-01

In the first part of this research thesis, the author recalls optical properties of electrons solvated in alcohols, and the various hypotheses of description of the mechanism of electron solvation in these polar environments. In the next parts, the author reports the study of reduced and oxidized species, presents a new model to explain the formation of aldehydes during the radiolysis of primary alcohols. He notices that this mode of formation does not comply with diffusion models. The FORTRAN software used for diffusion kinetic calculations, and experimental techniques are presented in appendix [fr

Pulse radiolysis of gases

International Nuclear Information System (INIS)

Nielsen, O.J.

1984-04-01

The pulse radiolysis equipment and technique are described and its relevance to atmospheric chemistry is discussed. Pulse radiolysis of a number of different chemical systems have been used to check the validity of the proposed mechanisms: 1) The hydrogen atom yield in the pulse radiolysis of H 2 was measured by four independent calibration techniques, using reactions of H with O 2 , C1NO, and HI. The H atom yield was compared with O 2 yields in pure O 2 and in O 2 /SF 6 mixtures which lead to a value G(H) = 17.6. The rate constants at room temperature of several reactions were determined. 2) OH radical reactions with tetraalkyllead at room temperature and with ethane, methane, and a series of C1- and F-substituted methanes at 300-400 K were studied. Arrhenius parameters, A and Esub(a), were determined for several reactions. The lifetime of Pb(CH 3 ) 4 and Pb(C 2 H 5 ) 4 in ambient air is estimated. CF 2 C1 2 was found to be a very efficient third body, M, in the reaction OH + OH + M arrow H 2 O 2 + M. 3) In the H 2 S systems the HS extinction coefficient at 3242 AA was determined to 9.5 x 10 2 cm -1 mol -1 . Four rate constants at room temperature were determined. (author)

Radiolysis: an efficient method of studying radicalar antioxidant mechanisms

International Nuclear Information System (INIS)

Gardes-Albert, M.; Jore, D.

1998-01-01

The use of the radiolysis method for studying radicalar antioxidant mechanisms offers the different following possibilities: 1- quantitative evaluation of antioxidant activity of molecules soluble in aqueous or non aqueous media (oxidation yields, molecular mechanisms, rate constants), 2- evaluation of the yield of prevention towards polyunsaturated fatty acids peroxidation, 3- evaluation of antioxidant activity towards biological systems such as liposomes or low density lipoproteins (LDL), 4- simple comparison in different model systems of drags effect versus natural antioxidants. (authors)

γ-radiolysis of benzophenone in heptane solutions

International Nuclear Information System (INIS)

Melekhonova, I.I.; Romantsev, M.F.; Saraeva, V.V.

1979-01-01

The radiolysis mechanism of 8x10 -3 M solutions of benzophenon in heptane at 0 deg C and a dose of 3.8x10 20 eV/ml, is studied. The radiolysis products (benzpinacol and benzhydrol with alkyl substitution in aromatic ring) are isolated by the thin-layer chromatography. The identification of the products is performed using infrared and mass spectroscopy. The mechanism of the process is considered based on the reactions of a triplet state of benzophenon

Mechanisms of transformation of the antioxidant kaempferol into depsides. Gamma-radiolysis study in methanol and ethanol.

Science.gov (United States)

Marfak, A; Trouillas, P; Allais, D P; Calliste, C A; Cook-Moreau, J; Duroux, J L

2003-09-01

In this study, we irradiated the antioxidant kaempferol in ethanol and methanol solutions with gamma rays at doses ranging from 0.2-20 kGy. NMR and ES-MS spectroscopy were used to identify radiolysis products. Two depsides, [2-[(4'-hydroxybenzoyl)oxy]-4,6-dihydroxyphenyl](oxo) methyl acetate and [2-[(4'-hydroxybenzoyl)oxy]-4,6-dihydroxyphenyl](oxo) ethyl acetate, were the major compounds of kaempferol degradation in methanol and in ethanol, respectively. Other products formed in low concentrations were identified as [4-hydroxyphenyl](oxo) methyl acetate, [4-hydroxyphenyl](oxo) ethyl acetate, and depside [2-[(4'-hydroxybenzoyl)oxy]-4,6-dihydroxyphenyl](oxo) acetic acid. The formation of the latter was observed in both solvents. We propose degradation mechanisms that suggest that (.)CH(2)OH and CH(3)(.)CHOH, produced by solvent radiolysis, react with the 3-OH kaempferol group because of its high H-donor capacity. pi-Electron delocalization in the flavonoxy formed after the first H-transfer leads to C-ring opening and consequently to the formation of depsides. G calculation of the degradation products and of (.)CH(2)OH and CH(3)(.)CHOH radicals confirmed the proposed mechanism of kaempferol radiolysis. The rate constants for the reaction between kaempferol and these free radicals were also calculated. Formation of depside has also been observed in many studies of the oxidation of flavonoids; those studying human metabolism have suggested similar redox transformation of flavonols. The antioxidant activities of radiolysis products were evaluated and compared to those of kaempferol.

ECP evaluation by water radiolysis and ECP model calculations

Energy Technology Data Exchange (ETDEWEB)

Hanawa, S.; Nakamura, T.; Uchida, S. [Japan Atomic Energy Agency, Tokai-mura, Ibaraki (Japan); Kus, P.; Vsolak, R.; Kysela, J. [Nuclear Research Inst. Rez plc, Rez (Czech Republic)

2010-07-01

In-pile ECP measurements data was evaluated by water radiolysis calculations. The data was obtained by using an in-pile loop in an experimental reactor, LVR-15, at the Nuclear Research Institute (NRI) in Czech Republic. Three types of ECP sensors, a Pt electrode, an Ag/AgCl sensor and a zirconia membrane sensor containing Ag/Ag{sub 2}O were used at several levels of the irradiation rig at various neutron flux and gamma rates. For water radiolysis calculation, the in-pile loop was modeled to several nodes following their design specifications, operating conditions such as flow rates, dose rate distributions of neutron and gamma-ray and so on. Concentration of chemical species along the water flow was calculated by a radiolysis code, WRAC-J. The radiolysis calculation results were transferred to an ECP model. In the model, anodic and cathodic current densities were calculated with combination of an electrochemistry model and an oxide film growth model. The measured ECP data were compared with the radiolysis/ECP calculation results, and applicability the of radiolysis model was confirmed. In addition, anomalous phenomenon appears in the in-pile loop was also investigated by radiolysis calculations. (author)

The reaction set, rate constants and g-values for the simulation of the radiolysis of light water over the range 20 deg to 350 deg C based on information available in 2008

International Nuclear Information System (INIS)

Elliot, A.J.; Bartels, D.M.

2009-08-01

An understanding of the aqueous radiolysis-induced chemistry in nuclear reactors is an important key to the understanding of materials integrity issues in reactor systems. Significant materials and chemistry issues have emerged in Pressurized Water Reactors (PWR), Boiling Water Reactors (BWR) and CANDU reactors that have required a detailed understanding of the radiation chemistry of the coolant. For each reactor type, specific computer radiolysis models have been developed to gain insight into radiolysis processes and to make chemistry control adjustments to address the particular issues. The objective of this report is to compile and review the radiolysis data now available and, where possible, correct the reported g-values and rate constants to provide a recommendation for the best values to use in high temperature modelling of light water radiolysis up to 350 o C. With a few exceptions, the review has been limited to those reactions that occur in slightly acid and slightly alkaline solutions, e.g., it does not address reactions involving the oxide radical anion, O - , or ionized forms of hydrogen peroxide, HO 2 - , beyond their acid-base equilibria reactions. However, a few reactions have been included where the rate constant for a reaction involving O - is significantly larger than the corresponding hydroxyl radical reaction rate constant and thus can influence the chemistry below the pK A of the hydroxyl radical. (author)

Radiolysis characterization of chloramphenicol in powder and in eye ointment

International Nuclear Information System (INIS)

Hong, L.; Altorfer, H.R.

2005-01-01

The effects of γ-radiation sterilization on chloramphenicol, in both pure powder state and petrolatum eye ointment, were investigated with high performance liquid chromatography. The content of chloramphenicol decreases by 1.0% in powder state and by 1.2% in eye ointment at the reference radiation dose of 25 kGy. The profile of chloramphenicol radiolysis products in powder state differs from that in eye ointment. It was found that microenvironment of chloramphenicol molecule is a key factor governing the radiolysis of chloramphenicol in powder state. Solvent residues in chloramphenicol powder could change the radiolysis behavior of chloramphenicol. The solvents, having good solubility for chloramphenicol, promote radiolytic hydrolysis of chloramphenicol, but the converses do not. Inert gas purging or diffusion by exposing in absorbent is efficient method to prevent chloramphenicol powder from radiolysis. The influence of the presence of oxygen was explored. Oxygen plays a role of scavenger and diminishes radiolysis of chloramphenicol. It was found that Nactyl-L-cysteine can protection chloramphenicol in eye ointment from radiolysis. Hydrophobic radiolysis products of chloramphenicol were observed in eye ointment part. Using scavengers and lower irradiation can be strategies to resist radiolysis of chloramphenicol in petrolatum eye ointment. (author)

Gamma-radiolysis of dimethyl sulfoxide. II. Radiolysis yields and possible mechanisms; Gamma-Radiolisis del dimetilsulfoxido II. Rendimientos radioloticos y posibles mecanismos

Energy Technology Data Exchange (ETDEWEB)

Gutierrez, M C; Barrera, R

1978-07-01

As result of quantitative studies on gamma-radiolysis of DMSO at a dose range of 90-850 Mrads, constant G values have been obtained for the following radiolysis compounds: G(-DMSO) - 6.7 {+-}0.2; G(dimethyl sulphide) - 3.4 {+-}0.3; G(methane) - 0,75 {+-} 0.04; G(dimethyl disulphide) -0.33 {+-}0,03; G(tri methylsulphonium methanesulphonate) - 0.26 {+-} 0,01; G(methyl methanethiosulphonate) - 0,25 {+-}0.02; G(dimethyl sulphona)-0.21{+-}0.02; G(H{sub 2})-0.18{+-}0.02; and G(propane)--0.0092{+-}0.0007. Initial G values have been obtained for other identified compounds: Gi(ethane)-0,46; Gi(CO)-0.052; and Gi(CO{sub 2})-0.030. Possible mechanisms on the radiolysis process are proposed. (Author) 17 refs.

Breaking time-resolution limits in pulse radiolysis

International Nuclear Information System (INIS)

Yang Jinfeng; Kondoh, Takafumi; Norizawa, Kimihiro; Yoshida, Yoichi; Tagawa, Seiichi

2009-01-01

Pulse radiolysis, which is a time-resolved stroboscopic method based on ultrashort electron pulse and ultrashort analyzing light, is widely used for the study of the chemical kinetics and radiation primary processes or reactions. Although it has become possible to use femtosecond-pulse electron beam and femtosecond laser light in pulse radiolysis, the resolution is limited by the difference in group velocities of the electrons and the light in sample. In this contribution, we introduce a concept of equivalent velocity spectroscopy (EVS) into pulse radiolysis and demonstrate the methodology experimentally. In EVS, both the electron and the analyzing light pulses precisely overlap at every point in the sample and throughout the propagation time by rotating the electron pulse. The advance allows us to overcome the resolution degradation due to the different group velocity. We also present a method for measuring the rotated angle of the electron pulse and a technique for rotating the electron pulse with a deflecting cavity.

Radiolysis of methylene blue studied by ESR

International Nuclear Information System (INIS)

Contineau, M.; Iliescu, C.; Ciureanu, M.

1983-01-01

Electron spin resonance spectra have been used to gain information on the mechanism of radiolysis of aqueous solutions of methylene blue. The identity and behaviour of the semiquinone radicals formed as intermediate reduction products were discussed for strongly acid and for alcaline solutions. In order to obtain information on the radiolytic mechanism in strongly acidic media, irradiation was performed in the presence of various types of scavengers: sodium formate, glucose, succinic acid, hydroquinone and D,L-α alanine. (author)

Radiation chemistry and advanced polymer materials studied by picosecond pulse radiolysis combined with femtosecond laser

International Nuclear Information System (INIS)

Tagawa, S.; Yoshida, Y.; Miki, M.; Yamamoto, T.; Ushida, K.; Izumi, Y.

1996-01-01

We have synchronized a single picosecond MeV electron pulse from L-band linear accelerator (linac) of The Institute of Scientific and Industrial Research of Osaka University to a single femtosecond laser pulse of Ti:Sapphire laser. It is an essential technique for the future femtosecond pulse radiolysis and is also applied to many kinds of combined application of more than two different beams from accelerators in very short time range. Radiation chemistry and new type of polymers have been studied by LL (laser-linac) twin picosecond pulse radiolysis. Especially the early events in radiation chemistry such as geminate recombination processes of electrons and radical cations are have been studied in both liquids and solids. (author)

Contribution to the study of gamma radiolysis of 2-furyl butyl or substituted phenyl ketones in isopropanol

International Nuclear Information System (INIS)

El Dessouky Aly, M.M.

1982-03-01

The following ketones: 2-furyl butyl ketone (I), 2 furyl phenyl ketone (II), 2-furyl p-methylphenyl ketone (III) and 2-furyl p-methoxyphenyl ketone (IV) were synthesised and characterised. The yields of hydrogen and methane obtained during radiolysis of the mixtures ketones (I to IV)-2-propanol were determined. These yields are always lower than with pure 2-propanol. Radiolysis products for ketones (I) and (II) are studied. Analysis of radiolitical products were conducted by gas chromatography. Effect of radiation dose and ketone concentration is determined. Reaction mechanisms are studied [fr

Radiolysis and radiosterilization of drugs

International Nuclear Information System (INIS)

Zeegers, F.; Crucq, A.S.; Gibella, M.; Tilquin, B.

1993-01-01

Can the absence of increased toxicological danger in irradiated foods be applied with confidence to drugs. The World Health Organization stated that up to 10 kGy there is no toxicological hazard. However, even if the irradiated drugs meet official standards, it would have to be established that any traces of radiolysis product formed are not toxic. All the tests from PHARMACOPEIA are not appropriate to detect the radiolysis and new physicochemical tests have to be used. Chromatographic detection of the radiosterilization of antibiotics may be advantageously used when the pharmaceuticals are not radio-resistant. The main obstacle to practical application is the low sensitivity of the detectors in liquid-liquid chromatography, a re-irradiation of the suspected samples will be necessary after preliminary chromatographic studies. 8 figs

One-electron oxidations of ferrocenes: a pulse radiolysis study

International Nuclear Information System (INIS)

Faraggi, Moshe; Weinraub, Dany; Broitman, Federico; DeFelippis, M.R.; Klapper, M.H.

1988-01-01

Using the pulse radiolysis technique we have studied the oxidation by various inorganic radicals of four water soluble ferrocene derivatives, hydroxyethyl, dimethylaminomethyl, monocarboxylic acid and dicarboxylic acid. We report the second order rate constants for these reactions, the stabilities and spectral properties of the ferrocinium products, and the electrochemically determined ferrocinium/ferrocene redox potentials. We also present preliminary estimates of tyrosine and tryptophan radical redox potentials obtained with the dicarboxylic acid ferrocene derivative as reference, and we discuss the relationship between redox potential differences and the reactivities of the ferrocenes with the inorganic radicals. (author)

Pulse radiolysis - new approaches to the classical technique

Energy Technology Data Exchange (ETDEWEB)

Zagorski, Z P [Institute of Nuclear Research, Warsaw (Poland)

1973-01-01

The present status of classical pulse radiolysis is described as well as trends in the further development of this technique (the investigation of radiolysis with nano- and picoseconds time resolution, new optica and electrochemical methods of intermediate species detection). The attention is concentrated on experimental difficulties of particular versions and the achievements are reviewed critically. This paper is the background for experiments being performed in the Institute of Nuclear Research on new techniques of pulse radiolysis.

Fuel-Coolant Interactions - some Basic Studies at the UKAEA Culham Laboratory

International Nuclear Information System (INIS)

Reynolds, J.A.; Dullforce, T.A.; Peckover, R.S.; Vaughan, G.J.

1976-01-01

In a hypothetical fault sequence important effects of fuel-coolant interactions include voiding and dispersion of core debris as well as the pressure damage usually discussed. The development of the fuel-coolant interaction probably depends on any pre-mixing Weber break-up that may occur, and is therefore a function of the way the fuel and coolant come together. Four contact modes are identified: jetting, shock tube, drops and static, and Culham's experiments have been mainly concerned with simulating the falling drop mode by using molten tin in water. It was observed that the fuel-coolant interaction is a short series of violent coolant oscillations centred at a localized position on the drop, generating a spray of submillimeter sized debris. The interaction started spontaneously at a specific time after the drop first contacted the water. There was a definite limited fuel-coolant interaction zone on a plot of initial coolant temperature versus initial fuel temperature outside which interactions never occurred. The. interaction time was a function of the initial temperatures. Theoretical scaling formulae are given which describe the fuel-coolant interaction zone and dwell time. Bounds of fuel and coolant temperature below which fuel-coolant interactions do not occur are explained by freezing. Upper bounds of fuel and coolant temperatures above which there were no fuel-coolant interactions are interpreted in terms of heat transfer through vapour films of various thicknesses. In conclusion: We have considered the effects of fuel-coolant interactions in a hypothetical fault sequence, emphasising that debris and vapour production as well as the pressure pulse can be important factors. The fuel-coolant interaction has been classified into types, according to possible modes of mixing in the fault sequence. Culham has been studying one type, the self-triggering of falling drops, by simulant experiments. It is found that there is a definite zone of interaction on a plot

Water Sorption and Gamma Radiolysis Studies for Uranium Oxides

Energy Technology Data Exchange (ETDEWEB)

Icenhour, A.S.

2002-02-27

During the development of a standard for the safe, long-term storage of {sup 233}U-containing materials, several areas were identified that needed additional experimental studies. These studies were related to the perceived potential for the radiolytic generation of large pressures or explosive concentrations of gases in storage containers. This report documents the results of studies on the sorption of water by various uranium oxides and on the gamma radiolysis of uranium oxides containing various amounts of sorbed moisture. In all of the experiments, {sup 238}U was used as a surrogate for the {sup 233}U. For the water sorption experiments, uranium oxide samples were prepared and exposed to known levels of humidity to establish the water uptake rate. Subsequently, the amount of water removed was studied by heating samples in a oven at fixed temperatures and by thermogravimetric analysis (TGA)/differential thermal analysis (DTA). It was demonstrated that heating at 650 C adequately removes all moisture from the samples. Uranium-238 oxides were irradiated in a {sup 60}Co source and in the high-gamma-radiation fields provided by spent nuclear fuel elements of the High Flux Isotope Reactor. For hydrated samples of UO{sub 3}, H{sub 2} was the primary gas produced; but the total gas pressure increase reached steady value of about 10 psi. This production appears to be a function of the dose and the amount of water present. Oxygen in the hydrated UO{sub 3} sample atmosphere was typically depleted, and no significant pressure rise was observed. Heat treatment of the UO{sub 3} {center_dot} xH{sub 2}O at 650 C would result in conversion to U{sub 3}O{sub 8} and eliminate the H{sub 2} production. For all of the U{sub 3}O{sub 8} samples loaded in air and irradiated with gamma radiation, a pressure decrease was seen and little, if any, H{sub 2} was produced--even for samples with up to 9 wt % moisture content. Hence, these results demonstrated that the efforts to remove trace

Chromatographic studies of gamma radiolysis products of phenols in methanolic solution

International Nuclear Information System (INIS)

Cordeiro, P.J.M.

1989-10-01

The radiolytic effects on phenolic compounds (catechol, resorcinol, hydroquinone and pyrogallol), under different doses of gamma irradiation, were studied. The results shown that the radiolytic effects are independent of the irradiation doses with almost all compounds formed from the solvent radiolysis. Analysis of the resulting products were carried out by High Performance Liquid Chromatography and Capillary Gas Chromatography. The quantification of these compounds was made by mass spectrometry. (author)

Physics study of Canada deuterium uranium lattice with coolant void reactivity analysis

Energy Technology Data Exchange (ETDEWEB)

Park, Jin Su; Lee, Hyun Suk; Tak, Tae Woo; Lee, Deok Jung [Ulsan National Institute of Science and Technology, Ulsan (Korea, Republic of); Shin, Ho Cheol [Korea Hydro and Nuclear Power Central Research Institute (KHNP-CRI), Daejeon (Korea, Republic of)

2017-02-15

This study presents a coolant void reactivity analysis of Canada Deuterium Uranium (CANDU)-6 and Advanced Canada Deuterium Uranium Reactor-700 (ACR-700) fuel lattices using a Monte Carlo code. The reactivity changes when the coolant was voided were assessed in terms of the contributions of four factors and spectrum shifts. In the case of single bundle coolant voiding, the contribution of each of the four factors in the ACR-700 lattice is large in magnitude with opposite signs, and their summation becomes a negative reactivity effect in contrast to that of the CANDU-6 lattice. Unlike the coolant voiding in a single fuel bundle, the 2 x 2 checkerboard coolant voiding in the ACR-700 lattice shows a positive reactivity effect. The neutron current between the no-void and voided bundles, and the four factors of each bundle were analyzed to figure out the mechanism of the positive coolant void reactivity of the checkerboard voiding case. Through a sensitivity study of fuel enrichment, type of burnable absorber, and moderator to fuel volume ratio, a design strategy for the CANDU reactor was suggested in order to achieve a negative coolant void reactivity even for the checkerboard voiding case.

Free radical reactions of hematoporphyrin: a pulse radiolysis study

International Nuclear Information System (INIS)

Ahmed, Mohammed; Guleria, Apurav; Singh, Ajay K.; Sarkar, S.K.

2011-01-01

Radiation chemistry of porphyrin derivatives has been given much attention in recent years. Although till date photo dynamic therapy (PDT) with Hematoporphyrin (HP) has already proved its effectiveness in the treatment of cancer, the molecular mechanisms by which this therapy-destroys tumour cells as well as its optimal physical parameters are still not fully understood. Thus it becomes necessary to understand the interaction of different free radicals with HP. Pulse radiolysis studies have been performed to understand the interaction of different free radicals with HP. The product formation along with bleaching and presence of a number of transients makes it difficult to pin point the mode and site of free radical attack. The radiation-induced formation of various transients (HP-OH, HO - , HP + ) in aqueous solution was investigated at various pHs by pulse radiolysis technique by means of N 3 , O - and CCl 3 O 2 radicals with and without triethyl-amine, under different dose conditions. The observed intermediates are characterized by their kinetic and spectroscopic data. The absorption spectrum of each transient could be differentiated from each other by their absorption maxima, extinction coefficients and kinetics. A clear indication of product formation has also been observed by employing continuous electron pulse and the solution shows a green coloration. It is conceivable that under certain conditions, similar transients may be produced when HP is used as a sensitizer in radiation chemotherapy of cancer patients. Our study may throw some light into the breakdown mechanism of haemoglobin to BV in addition to the understanding of free radical interaction of HP. (author)

Radiolysis of concentrated nitric acid solutions

International Nuclear Information System (INIS)

Nagaishi, R.; Jiang, P.Y.; Katsumura, Y.; Domae, M.; Ishigure, K.

1995-01-01

A study on electron pulse- and 60 Co γ-radiolysis of concentrated nitric acid and nitrate solutions has been carried out to elucidate the radiation induced reactions taking place in the solutions. Dissociation into NO 2 - and O( 3 P) was proposed as a direct action of the radiation on nitrate and gave the G-values were dependent on the chemical forms of nitrate: g s2 (-NO 3 - )=1.6 and g s2 (-HNO 3 )=2.2 (molecules/100eV). Based on the experimental yields of HNO 2 and reduced Ce IV , the primary yields of radiolysis products of water, g w , were evaluated to clarify the effects of nitrate on spur reactions of water in various nitrate solutions. (author)

Pulse radiolysis study on temperature and pressure dependence of the yield of solvated electron in methanol from room temperature to supercritical condition

International Nuclear Information System (INIS)

Han, Zhenhui; He, Hui; Lin, Mingzhang; Muroya, Yusa; Katsumura, Yosuke

2012-09-01

A new concept of nuclear reactor, supercritical water-cooled reactor (SCWR), has been proposed, which is based on the success of the use of supercritical water (SCW) in fossil fuel power plants for more than three decades. This new concept reactor has advantages of higher thermal conversion efficiency, simplicity in structure, safety, etc, and it has been selected as one of the reactor concepts for the next generation nuclear reactor systems. In these reactors, the same as in boiling water reactors (BWR) and pressurized water reactors (PWR), water is used not only as a coolant but also as a moderator. It is very important to understand the behavior of the radiolysis products of water under the supercritical condition, since the water is exposed to a strong radiation field under very high temperature condition. Usually, in order to predict the concentrations of water decomposition products with carrying out some kinds of computer simulations, knowledge of the temperature and/or pressure dependent G-values (denoting the experimentally measured radiolytic yields) as well as of the rate constants of a set of reactions becomes very important. Therefore, in recent years, two groups from Argonne National Laboratory and The University of Tokyo, simultaneously conducted two projects aimed at obtaining basic data on radiolysis of SCW. However, it is still lack of reliable radiolytic yields of water decomposition products in very high temperature region. As we known, the properties of solvated electrons in polar liquid are very helpful for our understanding how they play a central role in many processes, such as solvation and reducing reactions. The solvated electron can also be used as a probe to determine the dynamic nature of the polar liquid systems. Comparing to water, the primary alcohols have much milder critical points, for example, for water and methanol, the critical temperature and pressure are 374 deg. C and 22.1 MPa and 239.5 deg. C and 8.1 MPa, respectively

Impact of radiolysis and radiolytic corrosion on the release of {sup 13}C and {sup 37}Cl implanted into nuclear graphite: Consequences for the behaviour of {sup 14}C and {sup 36}Cl in gas cooled graphite moderated reactors

Energy Technology Data Exchange (ETDEWEB)

Moncoffre, N., E-mail: nathalie.moncoffre@ipnl.in2p3.fr [Université de Lyon, Université Lyon 1, CNRS/IN2P3, UMR5822, Institut de Physique Nucléaire de Lyon (IPNL) (France); Toulhoat, N. [Université de Lyon, Université Lyon 1, CNRS/IN2P3, UMR5822, Institut de Physique Nucléaire de Lyon (IPNL) (France); CEA/DEN, Centre de Saclay (France); Bérerd, N.; Pipon, Y. [Université de Lyon, Université Lyon 1, CNRS/IN2P3, UMR5822, Institut de Physique Nucléaire de Lyon (IPNL) (France); Université de Lyon, Université Lyon, IUT Lyon-1 département chimie (France); Silbermann, G. [Université de Lyon, Université Lyon 1, CNRS/IN2P3, UMR5822, Institut de Physique Nucléaire de Lyon (IPNL) (France); EDF – DPI - DIN – CIDEN, DIE - Division Environnement, Lyon (France); Blondel, A. [Université de Lyon, Université Lyon 1, CNRS/IN2P3, UMR5822, Institut de Physique Nucléaire de Lyon (IPNL) (France); Andra, Châtenay-Malabry (France); Galy, N. [Université de Lyon, Université Lyon 1, CNRS/IN2P3, UMR5822, Institut de Physique Nucléaire de Lyon (IPNL) (France); EDF – DPI - DIN – CIDEN, DIE - Division Environnement, Lyon (France); and others

2016-04-15

Graphite finds widespread use in many areas of nuclear technology based on its excellent moderator and reflector qualities as well as its strength and high temperature stability. Thus, it has been used as moderator or reflector in CO{sub 2} cooled nuclear reactors such as UNGG, MAGNOX, and AGR. However, neutron irradiation of graphite results in the production of {sup 14}C (dose determining radionuclide) and {sup 36}Cl (long lived radionuclide), these radionuclides being a key issue regarding the management of the irradiated waste. Whatever the management option (purification, storage, and geological disposal), a previous assessment of the radioactive inventory and the radionuclide's location and speciation has to be made. During reactor operation, the effects of radiolysis are likely to promote the radionuclide release especially at the gas/graphite interface. Radiolysis of the coolant is mainly initiated through γ irradiation as well as through Compton electrons in the graphite pores. Radiolysis can be simulated in laboratory using γ irradiation or ion irradiation. In this paper, {sup 13}C, {sup 37}Cl and {sup 14}N are implanted into virgin nuclear graphite in order to simulate respectively the presence of {sup 14}C, {sup 36}Cl and nitrogen, a {sup 14}C precursor. Different irradiation experiments were carried out using different irradiation devices on implanted graphite brought into contact with a gas simulating the coolant. The aim was to assess the effects of gas radiolysis and radiolytic corrosion induced by γ or He{sup 2+} irradiation at the gas/graphite interface in order to evaluate their role on the radionuclide release. Our results allow inferring that radiolytic corrosion has clearly promoted the release of {sup 14}C, {sup 36}Cl and {sup 14}N located at the graphite brick/gas interfaces and open pores.

Identification and evaluation of radiolysis products of irradiated chloramphenicol by HPLC-MS and HPLC-DAD

Energy Technology Data Exchange (ETDEWEB)

Hong, L; Altorfer, H R [Institute of Pharmaceutical Science, Swiss Federal Institute of Technology (ETH), Zurich (Switzerland); Horni, A; Hesse, M [Institute of Organic Chemistry, University of Zurich, Zurich (Switzerland)

2005-07-01

The radiolysis products of chloramphenicol under {gamma}-radiation sterilization were investigated systematically in the present study. Eight main radiolysis products were identified and quantified by HPLC-MS and HPLC-DAD, including two compounds that have never been reported. The minor radiolysis products were quantified, which shows that they are at the concentration levels below the threshold for identification. Carbon-carbon rupture reaction and oxidation reaction were proposed as the main radiolysis reactions of chloramphenicol powder. The applicability of {gamma}-sterilization for chloramphenicol products was quantitatively evaluated with qualitative and quantitative data and the data were compared to the threshold requirements of international regulations for identification. It was concluded that toxicities of the radiolysis products of chloramphenicol produced by {gamma}-radiation sterilization can be neglected, the radiolysis products are safe for human health from chemical view. (author)

Identification and evaluation of radiolysis products of irradiated chloramphenicol by HPLC-MS and HPLC-DAD

International Nuclear Information System (INIS)

Hong, L.; Altorfer, H.R.; Horni, A.; Hesse, M.

2005-01-01

The radiolysis products of chloramphenicol under γ-radiation sterilization were investigated systematically in the present study. Eight main radiolysis products were identified and quantified by HPLC-MS and HPLC-DAD, including two compounds that have never been reported. The minor radiolysis products were quantified, which shows that they are at the concentration levels below the threshold for identification. Carbon-carbon rupture reaction and oxidation reaction were proposed as the main radiolysis reactions of chloramphenicol powder. The applicability of γ-sterilization for chloramphenicol products was quantitatively evaluated with qualitative and quantitative data and the data were compared to the threshold requirements of international regulations for identification. It was concluded that toxicities of the radiolysis products of chloramphenicol produced by γ-radiation sterilization can be neglected, the radiolysis products are safe for human health from chemical view. (author)

Research on coolant radiochemistry

International Nuclear Information System (INIS)

Yeon, Jei Won; Kim, W. H.; Park, Y. J.; Im, J. K.; Jung, Y. J.; Jee, K. Y.; Choi, K. C.

2004-04-01

The final objective of this study is to develop the technology on the reduction of radioactive material formed in reactor coolant circuit. The contents of this study are composed of the simulation of primary cooling system, chemistry measurement technology in the high-temperature high-pressure environments, and coolant chemistry control technology. The main results are as follows; High-temperature and high-pressure loop system was designed and fabricated, which is to inducing CRUD growth condition on the surface of cladding. The high-temperature pH measurement system was established with YSZ sensing electrode and Ag/AgCl reference electrode. The performance of pH electrode was confirmed in the temperature range 200∼280 .deg. C. Coolant chemistry control technologies such as the neutron irradiation technique of boric acid solution, the evaluation on high-temperature electrochemical behavior of coolant, and the measurement of physicochemical properties of micro-particles were developed. The results of this study can be useful for the understanding of chemical phenomena occurred in reactor coolant and for the study on the reduction of radioactive material in primary coolant, which will be carried out in the next research stage

Influence of chemisorption products of carbon dioxide and water vapour on radiolysis of tritium breeder

Energy Technology Data Exchange (ETDEWEB)

Zarins, Arturs, E-mail: arturs.zarins@lu.lv [University of Latvia, Institute of Chemical Physics, Kronvalda Boulevard 4, LV-1010 Riga (Latvia); Kizane, Gunta; Supe, Arnis [University of Latvia, Institute of Chemical Physics, Kronvalda Boulevard 4, LV-1010 Riga (Latvia); Knitter, Regina; Kolb, Matthias H.H. [Karlsruhe Institute of Technology, Institute for Applied Materials (IAM-WPT), 76021 Karlsruhe (Germany); Tiliks, Juris; Baumane, Larisa [University of Latvia, Institute of Chemical Physics, Kronvalda Boulevard 4, LV-1010 Riga (Latvia)

2014-10-15

Highlights: • Chemisorption products affect formation proceses of radiation-induced defects. • Radiolysis of chemisorption products increase amount of radiation-induced defects. • Irradiation atmosphere influence radiolysis of lithium orthosilicate pebbles. - Abstract: Lithium orthosilicate pebbles with 2.5 wt% excess of silica are the reference tritium breeding material for the European solid breeder test blanket modules. On the surface of the pebbles chemisorption products of carbon dioxide and water vapour (lithium carbonate and hydroxide) may accumulate during the fabrication process. In this study the influence of the chemisorption products on radiolysis of the pebbles was investigated. Using nanosized lithium orthosilicate powders, factors, which can influence the formation and radiolysis of the chemisorption products, were determined and described as well. The formation of radiation-induced defects and radiolysis products was studied with electron spin resonance and the method of chemical scavengers. It was found that the radiolysis of the chemisorption products on the surface of the pebbles can increase the concentration of radiation-induced defects and so could affect the tritium diffusion, retention and the released species.

Effect of nitrogen and oxygen on radiolysis of iodide solution

Energy Technology Data Exchange (ETDEWEB)

Karasawa, H; Endo, M [Hitachi Ltd., Power and Industrial System R+D Divisions, Ibaraki (Japan)

1996-12-01

The effect of nitrogen and oxygen on radiolysis of iodide solution was examined. Direct decomposition of nitrogen by {gamma}-radiation produced nitric acid to decrease a water pH. This resulted in the iodine formation in the radiolysis of iodide solution. Hydrogen peroxide was produced by the radiolysis of water containing oxygen. This worked a reducing agent to suppress the formation of iodine in the radiolysis of iodide solution. In the analytical model, fourteen iodine species were considered and reaction scheme consisted in 124 reactions. The analytical model could estimate the oxidation state of iodide ions. (author) 4 figs., 4 refs.

Determination of oxidation products in radiolysis of halophenols with pulse radiolysis, hplc, and ion chromatography

International Nuclear Information System (INIS)

Ye, M.; Schuler, R.H.

1990-01-01

This paper reports on hydroxyl radicals that react with halogen substituted phenols by several different ways. One is addition of OH radicals to the aromatic ring, which is followed by elimination of hydrogen halide, H 2 O or H - . The positions of OH radicals attack are dependent on the nature of the halogen which affects the electronic distribution in the ring. The oxidation of fluorophenols, chlorophenols and bromophenols with hydroxyl radicals in N 2 O saturated solution has been investigated with pulse radiolysis and γ-irradiation experiments. The intermediates of the reactions were studied by pulse radiolysis. The products created in the γ-irradiation of aqueous solutions of halophenols were analyzed by ion chromatography and high performance liquid chromatography (HPLC). With the combination of time-resolved and steady-state experiments a complete and detailed description of radiolytic oxidation of halophenols by hydroxyl radicals was obtained

Testing requirements for SCWR radiolysis

International Nuclear Information System (INIS)

Guzonas, D.; Stuart, C.; Jay-Gerin, J.-P.; Meesungnoen, J.

2010-01-01

The Generation IV supercritical water-cooled reactor (SCWR) designs under consideration would operate at ∼430-625 o C and 25 MPa, i.e., well beyond the thermodynamic critical point of water. Supercritical (light/heavy) water (SCW)-cooled reactors would enable thermodynamic cycle efficiencies as high as ∼44% (versus ∼33% for existing water reactors), thus generating lower-cost electricity. The purpose of this report is to survey the literature on SCW radiolysis, describe the recent modeling performed at the Universite de Sherbrooke, and to broadly outline the testing required to develop a benchmarked SCW radiolysis model. (author)

Study of the mechanism of the gamma radiolysis of saccharose and its derivatives in aqueous or solid phase. Study by spin trapping

International Nuclear Information System (INIS)

Triolet, J.

1991-01-01

Powder or aqueous solutions of saccharose, deoxysaccharose and fructanes are irradiated. Radicals created during gamma radiolysis are converted into sugar-nitroxide radicals by reaction with 2 methyl 2 nitroso-propane. They are stable enough to be studied in solution by electron paramagnetic resonance (EPR) coupled or not to high performance liquid chromatography. EPR spectra obtained are simulated with the Voyons program for the determination of spectrocopic characteristics of trapped species. The study of glucosides, disaccharides and sugar labelled with carbon 13 allows to suggest a chemical structure for 5 out of the 7 species trapped during saccharose radiolysis. Influence of irradiation conditions is studied and mechanisms are proposed [fr

Pulse radiolysis studies of proline-ninhydrin complex

Energy Technology Data Exchange (ETDEWEB)

Barik, A; Priyadarsini, K I [Radiation and Photochemistry Division, Behabha Atomic Research Centre, Trombay, Mumbai (India); Prabhakar, K R; Veerapur, V P; Unnikrishnan, M K [Department of Pharmacology, Manipal College of Pharmaceutical Sciences (India)

2006-07-01

Proline-Ninhydrin (PN) complex has earlier been reported by us to be an excellent free radical scavenger and also examined for in vitro and in vivo radioprotection. Here we present mechanism of reaction of PN complex with hydroxyl ({sup .}OH) radicals and other oxidants and compared the results with proline and ninhydrin independently. PN complex was prepared by mixing in 1:1 stoichiometric ratio of proline and ninhydrin in a ball mill at 40 degree C and purified by crystallisation. Parent absorption spectra of PN complex show peak at 300 nm and 304 nm with a ground state pK{sub a} of 9.3. The reaction of {sup .}OH radical and other one-electron oxidants were studied using 7 MeV electron pulses from LINAC and the dose determined by aerated KSCN dosimeter. {sup .}OH radical reaction with PN studied at pH 6.8 produced a transients having broad absorption band at 400 nm. The reaction of {sup .}OH with PN complex was found to be dependent on the pH of the solution, at pH > 8 the transient absorption band shifted to 360 nm. The pK{sub a} of the transient was measured by following these absorption changes with varying the pH from 2 to 11 to be 6.9. OH radical reactions with the organic substrates is non-selective in nature and in order to establish the nature of the transient absorption band, pulse radiolysis studied were carried out with specific one electron oxidants, SO{sub 4}{sup .-} radical and Cl{sub 2}{sup .-} radical, which showed the transient absorption band with maximum at 440 nm and 350 nm respectively, indicating that the reaction {sup .}OH with PN complex at pH 7 is not by oxidation but by addition reaction to the aromatic ring. The reaction of H atom with PN complex was carried out in presence of tert-butanol at pH 1. The transient showed similar spectrum as observed with reaction OH radical reaction. As the H atom proceeds through mostly abstraction reaction, the transient formed by H atom and OH radical at low pH produces H atom abstracted species of the

Pulse radiolysis facilities and activities in Japan

International Nuclear Information System (INIS)

Ogasawara, M.

1995-01-01

Pulse radiolysis studies in Japan have been reviewed in special reference to the facilities and the people who have engaged in the experiments. Main achievement is summarized with the list of selected publications. (author)

Radiolysis of chitosan derivatives exhibiting antimutagenic activity

International Nuclear Information System (INIS)

Aleksandrova, V.A.; Kuzina, S.I.; Shilova, I.A.; Mikhajlov, A.I.

2006-01-01

The radiolysis of antimutagens extracted from natural biopolymer chitosan was studied by the EPR. The radiolysis of test samples of biopolymers and gallic acid was performed in vacuum at 77 K using a 60 Co γ-radiation source, with radiation doses 50 kGy. It was shown that addition of gallic acid (2 mol %) to quaternized chitosan results in a 2.5-fold decrease in the radiation-chemical yield of radicals and a nearly complete inhibition of the formation of ion radicals. Gallic acid units likely play the role of a stabilizer that protects the polycation from radiation damage and, hence, the structure of the cationogenic units from changes, thereby improving the antimutagenic properties of the system [ru

Alpha Radiolysis of Sorbed Water on Uranium Oxides and Uranium Oxyfluorides

Energy Technology Data Exchange (ETDEWEB)

Icenhour, A.S.

2003-09-10

The radiolysis of sorbed water and other impurities contained in actinide oxides has been the focus of a number of studies related to the establishment of criteria for the safe storage and transport of these materials. Gamma radiolysis studies have previously been performed on uranium oxides and oxyfluorides (UO{sub 3}, U{sub 3}O{sub 8}, and UO{sub 2}F{sub 2}) to evaluate the long-term storage characteristics of {sup 233}U. This report describes a similar study for alpha radiolysis. Uranium oxides and oxyfluorides (with {sup 238}U as the surrogate for {sup 233}U) were subjected to relatively high alpha radiation doses (235 to 634 MGy) by doping with {sup 244}Cm. The typical irradiation time for these samples was about 1.5 years, which would be equivalent to more than 50 years irradiation by a {sup 233}U sample. Both dry and wet (up to 10 wt % water) samples were examined in an effort to identify the gas pressure and composition changes that occurred as a result of radiolysis. This study shows that several competing reactions occur during radiolysis, with the net effect that only very low pressures of hydrogen, nitrogen, and carbon dioxide are generated from the water, nitrate, and carbon impurities, respectively, associated with the oxides. In the absence of nitrate impurities, no pressures greater than 1000 torr are generated. Usually, however, the oxygen in the air atmosphere over the oxides is consumed with the corresponding oxidation of the uranium oxide. In the presence of up to 10 wt % water, the oxides first show a small pressure rise followed by a net decrease due to the oxygen consumption and the attainment of a steady-state pressure where the rate of generation of gaseous components is balanced by their recombination and/or consumption in the oxide phase. These results clearly demonstrate that alpha radiolysis of either wet or dry {sup 233}U oxides will not produce deleterious pressures or gaseous components that could compromise the long-term storage of

Influence of radiolysis on UO2 fuel matrix dissolution under disposal conditions. Literature Study

International Nuclear Information System (INIS)

Ollila, K.

2011-05-01

The objective of this study was to examine the recent published literature on the influence of water radiolysis on UO 2 fuel matrix dissolution under the disposal conditions. The α radiation is considered to be dominating over the other types of radiations at times longer than 1000 years. The presence of the anaerobic corrosion products of iron, especially of hydrogen, has been observed to play an important role under radiolysis conditions. It is not possible to exclude gamma/beta radiolysis effects in the experiments with spent fuel, since there is not available a fuel over 100 years old. More direct measurements of α radiolysis effects have been conducted with α doped UO 2 materials. On the basis of the results of these experiments, a specific activity threshold to observe α radiolysis effects has been presented. The threshold is 1.8 x 10 7 to 3.3 x 10 7 Bq/g in anoxic 10 -3 M carbonate solution. It is dependent on the environmental conditions, such as the reducing buffer capacity of the conditions. The results of dissolution rate measurements at VTT with 233 U-doped UO 2 samples in 0.01 to 0.1 M NaCl solutions under anoxic conditions did not show any effect of α radiolysis with doping levels of 5 and 10% 233 U (3.2 x 10 7 and 6.3 x 10 7 Bq/g). Both Fe 2+ and hydrogen can act as reducing species and could react with oxidizing radiolytic species. Fe 2+ concentrations of the order of 10 -5 M can decrease the rate of H 2 O 2 production. Low dissolution rates, 2 x 10 -8 to 2 x 10 -7 /yr, have been measured in the presence of metallic Fe with 5 and 10% 233 U-doped UO 2 in 0.01 to 1 M NaCl solutions. The tests with isotope dilution method showed precipitation phenomena of U to occur during dissolution process. The concentrations of dissolved U were extremely low (≤ 8.4 x 10 -11 M). No effects of -radiolysis could be seen. It is difficult to distinguish the effects of metallic Fe, Fe 2+ or hydrogen in these tests. Hydrogen could also act as a reducing agent

Characterisation and activation of catalysts for recombination of radiolysis gas

International Nuclear Information System (INIS)

Bolz, Michael; Koehler, Jan; Schorle, Rolf; Helf, Achim

2011-01-01

Radiolysis gas is produced by radiolysis of cooling water during the operation of boiling water reactors. Small amounts of radiolysis gas can accumulate at dead ends of pipes in the water-steam circuit. Under certain conditions, it can accumulate even to higher concentrations. To avoid these accumulations, small catalysts are built in. As part of a diploma thesis, the catalysts were analysed and characterised. (orig.)

Recovery studies for plutonium machining oil coolant

International Nuclear Information System (INIS)

Navratil, J.D.; Baldwin, C.E.

1977-01-01

Lathe coolant oil, contaminated with plutonium and having a carbon tetrachloride diluent, is generated in plutonium machining areas at Rocky Flats. A research program was initiated to determine the nature of plutonium in this mixture of oil and carbon tetrachloride. Appropriate methods then could be developed to remove the plutonium and to recycle the oil and carbon tetrachloride. Studies showed that the mixtures of spent oil and carbon tetrachloride contained particulate plutonium and plutonium species that are soluble in water or in oil and carbon tetrachloride. The particulate plutonium was removed by filtration; the nonfilterable plutonium was removed by adsorption on various materials. Laboratory-scale tests indicated the lathe-coolant oil mixture could be separated by distilling the carbon tetrachloride to yield recyclable products

The Reaction Mechanism and Rate Constants in the Radiolysis of Fe2+-Cu2+ Solutions

DEFF Research Database (Denmark)

Bjergbakke, Erling; Sehested, Knud; Rasmussen, O. Lang

1976-01-01

Pulse radiolysis and gamma radiolysis have been used to study the reaction mechanism in the radiolysis of aqueous solutions of Fe2+ and Cu2+. A reaction scheme has been developed and confirmed by computation of the corresponding complete set of differential equations. The rate constants for some ...... 10^{8}$ and $1.3\\times 10^{8}\\ {\\rm mol}^{-1}\\ {\\rm sec}^{-1}$ in pH 2.1 H2 SO4 and HClO4, respectively.......Pulse radiolysis and gamma radiolysis have been used to study the reaction mechanism in the radiolysis of aqueous solutions of Fe2+ and Cu2+. A reaction scheme has been developed and confirmed by computation of the corresponding complete set of differential equations. The rate constants for some...... of the reactions have been determined at different pH's. $k_{{\\rm Cu}^{+}+{\\rm O}_{2}}=4.6\\times 10^{5}$ and $1.0\\times 10^{6}\\ {\\rm mol}^{-1}\\ {\\rm sec}^{-1}$, $k_{{\\rm Cu}^{+}+{\\rm Fe}^{3+}}=5.5\\times 10^{6}$ and $1.3\\times 10^{7}\\ {\\rm mol}^{-1}\\ {\\rm sec}^{-1}$, $k_{{\\rm Cu}({\\rm III)}+{\\rm Fe}^{2+}}=3.3\\times...

Application of chemsimul for groundwater radiolysis

DEFF Research Database (Denmark)

Christensen, Hilbert; Bjergbakke, Erling

1986-01-01

The application of the radiation chemical computer program chemsimul, for the calculation of radiolysis in connection with the storage of high level waste has been studied. Methods have been developed for the diffusion of gases out of the irradiated system, for the continuous addition of Fe2...

Radical production in the radiolysis of benzene

International Nuclear Information System (INIS)

LaVerne, J.A.; Araos, M.S.

1998-01-01

Complete text of publication follows. Benzene is the prototypical aromatic compound and yet the radiation chemistry of the radicals formed in its radiolysis is not well understood. Temporal information on the yield of phenyl radical, the major radical produced in the radiolysis, is important for understanding the radiation chemistry of many other types of aromatic compounds including some polymers. The effects of track structure on the production of phenyl radicals have been examined using iodine-scavenging techniques. The variation of the yields of iodobenzene and the other major molecular products such as biphenyl as a function of iodine concentration gives a good indication of the competition kinetics occurring in particle tracks. Experimental results of the scavenger experiments will be shown and their implications in the radiolysis of condensed hydrocarbons will be discussed

Studies on radiolysis of amino acids, 1

International Nuclear Information System (INIS)

Oku, Tadatake

1977-01-01

In order to elucidate the radiolysis of amino acid, peptide, protein and enzyme, the radiolytic mechanisms of neutral amino acids (glycine, L-alanine, L-valine, L-leucine, L-isoleucine, L-serine, and L-threonine) and acidic amino acids (L-aspartic acid, L-glutamic acid and DL-amino-n-adipic acid) were studied in the presence of air or in the atmosphere nitrogen. An aqueous solution of 1 mM. of each amino acid was sealed in a glass ampoule under air or nitrogen. Irradiation of amino acid solutions was carried out with γ-rays of 60 Co at doses of 4.4-2,640x10 3 rads. The amino acids and the radiolytic products formed were determined by ion-exchange chromatography. From the results of determining amino acids and the radiolytic products formed and their G-values, the radiolytic mechanisms of the amino acids were discussed. (auth.)

Pulse radiolysis of 9,10-anthraquinone in methanol

International Nuclear Information System (INIS)

Mayer, J.; Krasiukianis, R.

1990-01-01

The reactions of anthraquinone with intermediates in methanol (e 2 - , . CH 2 O - , . CH 2 OH) were investigated using γ-radiolysis and pulse radiolysis method. The anthraquinone radical anions are reactive towards O 2 (ca 3 x 10 8 mol -1 dm 3 s -1 ) and can disproportionate giving corresponding dianion. (author)

Design guideline to prevent the pipe rupture by radiolysis gases in BWR steam piping

International Nuclear Information System (INIS)

Inagaki, T.; Miyagawa, M.; Ota, T.; Sato, T.; Sakata, K.

2009-01-01

In late 2001, pipe rupture accidents due to fast combustion of radiolysis gas occurred in Japan and elsewhere's BWR power plants. TENPES began to set up the guideline as action to such a new problem to prevent accumulation and combustion of radiolysis gas in BWR steam piping. And then, the first edition of guideline was published in October 2005. Afterwards, the experimental study about combustion/detonation of radiolysis gas have been continued. And in March 2007, TENPES published a revised edition of the guideline. This is the report of the revised edition of that guideline. According to this guideline, it became possible to design BWR's steam piping to prevent accumulation of radiolysis gas. (author)

Radiolysis of phenol in aqueous solution at elevated temperatures

International Nuclear Information System (INIS)

Miyazaki, Toyoaki; Katsumura, Yosuke; Lin Mingzhang; Muroya, Yusa; Kudo, Hisaaki; Taguchi, Mitsumasa; Asano, Masaharu; Yoshida, Masaru

2006-01-01

γ-Radiolysis and pulse radiolysis of phenol in aqueous solution up to supercritical condition have been carried out. G-values of phenol consumption and product formation have been determined. While dihydroxybenzenes were major products at room temperature, multi-ring compounds and benzene were formed above 300 deg. C. This indicates reaction mechanism was changed above 300 deg. C, where phenoxyl radical plays a predominant role. This is supported by the observation of phenoxyl radical in pulse radiolysis. In supercritical water, the G-values increased with decrease of density

Study of the radiolysis of succinic acid - applications in the dosimetry of high doses

International Nuclear Information System (INIS)

Andrade e Silva, L.G.

1978-01-01

A study is made of the effect of the gama radiation dose and of particle size of succinic acid (fine powder of large crystals) in relation with the formation of CO 2 and CO + H 2 , which are the main gaseous products of radiolysis. A different yield of CO + H 2 is found when the succinic acid is used as powder compared to the material in the form of large crystals. The reason for this difference is searched, studying the influence of heating and sublimation of the succinic acid prior to irradiation. The influence, in the mentioned yield, of the surface area of succinic acid particles, of the presence of oxygen (air) and of the rapid recrystallization of the acid are also studied. The formation of intermediate species in the radiolysis of succinic acid is examined. The system used in ethanol-succinic acid at 77K. Analysis are made using an electronic paramagnetic resonance spectrometer. The possibility of using succinic acid as a dosimeter for high level gama radiation doses is discussed [pt

Temporal behavior of hydrated electron studied up to 400 deg. C by ultrafast pulse radiolysis and Monte Carlo calculation

International Nuclear Information System (INIS)

Katsumura, Yosuke; Muroya, Yusa; Lin, Mingzhang; Yu, Yan; Mehran, Mostafavi; Sanguanmith, Sunuchakan; Meesungnoen, Jintana; Jay-Gerin, Jean-Paul

2012-09-01

Pulse radiolysis is a very powerful and unique method to observe the transient species and to determine their yields and has been widely used up to now. Since the radiation-induced reactions at elevated temperatures are accelerated, precise measurement becomes difficult by the conventional pulse radiolysis systems. Then, a higher time resolved pulse radiolysis system is highly expected. Recently, an ultrafast pulse radiolysis system has been developed in the University of Tokyo and applied to water radiolysis at elevated temperatures [1]. Temporal behavior of the hydrated electron at elevated temperatures up to 400 deg C has been detected. The time dependent behavior of hydrated electron at elevated temperatures were detected and the latest version of the Monte Carlo simulation code developed at University of Sherbrooke was applied to reproduce the experimental results. From the simulation, it was made clear that the thermalization distance becomes smaller with increasing temperature. In addition, in supercritical water, the initial yield is significantly dependent on density (pressure), which is consistent with our previous evaluation. (authors)

A pulse radiolysis study of hyperoside isolated from Hypericum mysorense

International Nuclear Information System (INIS)

Hariharapura, Raghu C.; Mahal, H.S.; Srinivasan, R.; Jagani, Hitesh; Vijayan, P.

2015-01-01

Background: The recent growth in knowledge of free radicals in biology is producing a medical revolution that promises a new age in health and disease management. In the last two decades there has been an explosive interest in the role of oxygen free radicals, more generally known as “reactive oxygen species” and of “reactive nitrogen species” in experimental and clinical medicine. Methods: The flowering top extract of Hypericum mysorense possessing potent anti-oxidant activity was subjected to bio-active guided isolation. Pulse radiolysis technique was used to determine the transient spectrum and rate constant for the one-electron oxidation of hyperoside by · OH, N 3 · , NO 2 · , NO · , CCl 3 OO · radicals in aqueous solution. Results: Three compounds were isolated and characterized as rutin, quercetin-3-O-galactoside (hyperoside) and quercetin from spectral analysis. The hyperoside radical showed pK a1 and pK a2 at 5.4 and 9.2. Both, Cu(II) and iron(II) ions form chelate with hyperoside. The Cu–hyperoside chelate was able to scavenge O 2 ·− , k=7.0(±0.3)×10 6 dm 3 mol −1 s −1 at pH 9. The repair rates for tryptophan and guanosine radicals by hyperoside were also determined. Conclusion: The reduction potential of hyperoside radical was determined by cyclic voltammetric and pulse radiolysis methods. - Highlights: • Hyperoside, rutin and quercetin were isolated from extract of Hypericum mysorense. • Rate constant of hyperoside was determined by Pulse radiolysis technique. • The hyperoside radical showed pK a1 and pK a2 at 5.4 and 9.2. • Cu(II) and iron(II)ions form chelate with hyperoside. • Hyperoside can repair the damage to guanosine, tryptophan radicals

Formation of stable radicals during perfluoroalkane radiolysis

International Nuclear Information System (INIS)

Allayarov, S.R.; Demidov, S.V.; Kiryukhin, D.P.; Mikhajlov, A.I.; Barkalov, I.M.

1984-01-01

Accumulation and stabilization kinetics of perfluoroalkyls during α-radiolysis ( 60 Co) of perfluoralkanes (PFA) in a wide temperature range for different PFA fractions differing in the average molecular weight, is investigated. It is noted that low temperature (PFA) radiolysis (77 K) is of a linear nature of accumulation of stabilized radicals up to doses of approximately 700 KGy. In the case of PFA radiolysis at 300 K radiation yields of stable radicals are somewhat lower than at 47 K and at doses of 200-300 KGy, their accumulation ceases. It is shown that kinetics of formation and accumulation of stable radicals does not depend on molecular mass and PFA fraction viscosity. Perfluoroalkyl stability is explained by intra molecular conformation spheric insulation of the free valency. Perfluoroalkyl stability in different PFA fractions in a wide time range in different media is investigated

Radiolysis of cyanocobalamin (vitamin B12)

International Nuclear Information System (INIS)

Juanchi, X.; Albarran, G.; Negron-Mendoza, A.

2000-01-01

Research on the radiolysis of vitamins is of considerable interest since these compounds are important nutritional constituents in foods and in dietetic supplements. In spite of these considerations there are few data and very often difficult to compare for the radiolytic behavior of vitamins. In this work we focused our attention on to the study of the radiolysis of cyanocobalamin (vitamin B 12 ) in solid state and in aqueous solutions. The procedure was followed by HPLC and UV-spectroscopy. The results obtained in aqueous solutions showed a dependence of the decomposition as a linear function of the dose. The G of decomposition for a 1x10 -5 M solution was 3.3. In the solid state the vitamin was very stable towards the irradiation in the conditions used in this study with a G=2.1x10 -3 . A study made with Serratia marcescens as a microbiological contaminant showed that at the sterilization dose there is a destruction of the vitamin in aqueous solution. In the solid state the degree of decomposition was 7%. (author)

Proton Pulse Radiolysis

Energy Technology Data Exchange (ETDEWEB)

Christensen, H C; Nilsson, G; Reitberger, T; Thuomas, K A

1973-03-15

A 5 MeV proton accelerator (Van de Graaff) has been used for pulse radiolysis of a number of organic gases and the transient spectra obtained from the alkanes methane, ethane, propane, n-butane and neopentane have tentatively been assigned to alkyl radicals. Some methodological aspects of this new technique are discussed

Study of radicals or radical ions formed by radiolysis of n-methylacetamide and of its mixtures with water and some organic solvents. Problem of solvation of electrons in structured media

International Nuclear Information System (INIS)

Tran-Thi, Thu-Hoa

1978-01-01

Based on two hypotheses (effect of structure, and electron affinity), and on the use of two complementary techniques (pulsed radiolysis and gamma radiolysis), this research thesis reports the study of the fate of primary species formed during the radiolysis of N-methylacetamide, either pure or mixed with other solvents. The author first presents experimental conditions, the experimental techniques and their results for both types of radiolysis, and then discusses these results

Radiolysis effects in sub-cooled nucleate boiling

International Nuclear Information System (INIS)

Dickinson, S.; Henshaw, J.; Tuson, A.; Sims, H.E.

2002-01-01

A hydrogen depleted region may form in the water during bubble formation when boiling occurs in a PWR. This would arise from stripping of gases into the steam phase. The depleted water may then become oxidising due to radiolysis forming H 2 O 2 . The presence of radiolytic oxidising conditions is one of the mechanisms proposed to explain deposits formed in Axial Offset Anomalies. This work describes a model that has been developed to examine this behaviour. The model deals with bubble growth and material transport as well as the radiolysis chemistry. The model simulates diffusion of species through the gas/liquid boundary layer. The appropriate mass conservation equations for this problem are described and the results of their numerical solution discussed. This model indicates the importance of the assumed boundary conditions on the results of the calculations. These boundary conditions are discussed in detail and the most appropriate ones for the actual reactor situation are outlined. The conclusion of this modelling study is that at normal PWR operating conditions of 40 cc H 2 (STP) kg -1 it is unlikely that radiolysis in a subcooled boiling region would be important. The situation is more ambiguous at the 1 to 5 cc H 2 (STP) kg -1 range. (author)

Radiolysis effects in sub-cooled nucleate boiling

Energy Technology Data Exchange (ETDEWEB)

Dickinson, S.; Henshaw, J.; Tuson, A.; Sims, H.E. [AEA Technology (United Kingdom)

2002-07-01

A hydrogen depleted region may form in the water during bubble formation when boiling occurs in a PWR. This would arise from stripping of gases into the steam phase. The depleted water may then become oxidising due to radiolysis forming H{sub 2}O{sub 2}. The presence of radiolytic oxidising conditions is one of the mechanisms proposed to explain deposits formed in Axial Offset Anomalies. This work describes a model that has been developed to examine this behaviour. The model deals with bubble growth and material transport as well as the radiolysis chemistry. The model simulates diffusion of species through the gas/liquid boundary layer. The appropriate mass conservation equations for this problem are described and the results of their numerical solution discussed. This model indicates the importance of the assumed boundary conditions on the results of the calculations. These boundary conditions are discussed in detail and the most appropriate ones for the actual reactor situation are outlined. The conclusion of this modelling study is that at normal PWR operating conditions of 40 cc H{sub 2} (STP) kg{sup -1} it is unlikely that radiolysis in a subcooled boiling region would be important. The situation is more ambiguous at the 1 to 5 cc H{sub 2} (STP) kg{sup -1} range. (author)

Redox reactions of tocopherol monoglucoside in aqueous solutions. A pulse radiolysis study

Energy Technology Data Exchange (ETDEWEB)

Kapoor, S.; Mukherjee, T.; Nair, C.K.K. [Bhabha Atomic Research Centre, Mumbai (India); Kagiya, Tsutomu V. [Health Research Foundation, Kyoto (Japan)

2002-03-01

The reactions between tocopherol monoglucoside (TMG), a water-soluble vitamin-E derivative, with Br{sub 2}{sup {center_dot}}{sup -}, N{sub 3}{sup {center_dot}}, (SCN){sub 2}{sup {center_dot}}{sup -}, NO{sub 2}{sup {center_dot}}, OH{sup {center_dot}} and various halogenated peroxyl radicals were examined using a pulse radiolysis technique. The results demonstrate that TMG forms a stable phenoxyl radical at pH>6.8. The thus-formed phenoxyl radical shows pH-dependent decay kinetics and is disproportionated by 2nd order kinetics at pH2.3. It was observed that the TMG reactivity towards a halogenated peroxyl radical increases with the number of halogen atoms at the carbon atom having a peroxyl group. The reaction between the TMG phenoxyl radical and ascorbic acid was also examined using a pulse radiolysis technique. The results indicate that the TMG phenoxyl radical is repaired by ascorbate. Kinetic studies indicate that TMG may act as an antioxidant to repair free-radical damage to some biologically importnat compounds. The one-electron reduction potential for TMG was found to be 0.522 V{+-}0.06 vs. NHE. (author)

The radiolysis of lithium oxide ceramics

Energy Technology Data Exchange (ETDEWEB)

Tiliks, J; Supe, A; Kizane, G; Tiliks, J Jr [Latvia Univ., Riga (Latvia). Dept. of Chemistry; Grishmanov, V; Tanaka, S

1998-03-01

The radiolysis of Li{sub 2}O ceramics exposed to accelerated electrons (5 MeV) at 380 K was studied in the range of high absorbed doses up to 250 MGy. The formation of radiation defects (RD) and radiolysis products (RP) was demonstrated to occur simultaneously in the regions of (1) the regular crystalline lattice and (2) an enhanced content of the intrinsic defects and impurities. The production of the electronic RD and RP is more efficient in the region of the defected lattice than that at the site of the regular crystalline lattice. However, the stability of RD and RP formed in the region of the intrinsic defects is far less than those produced at the crystalline lattice, since most of the first mentioned RD and RP disappears with irradiation dose due to the radiation stimulated recombination. By this means the enhanced quantity of RD and RP is localized in the Li{sub 2}O ceramics irradiated to absorbed dose of 40-50 MGy, and hence this can influence the tritium release parameters. As soon as the intrinsic defects have been consumed in the production of RD and RP and the recombination of unstable electronic RD and RP takes place (at dose of {approx}100 MGy), the radiolysis of Li{sub 2}O ceramics occurs only at the crystalline lattice. Furthermore, the concentration of RD and RP increases monotonically and tends to the steady-state level. (author)

Properties of the radicals formed by one-electron oxidation of acetaminophen - a pulse radiolysis study

International Nuclear Information System (INIS)

Bisby, R.H.; Tabassum, N.

1988-01-01

The semi-iminoquinone radical of acetaminophen, which has previously been proposed as a possible hepatotoxic intermediate in the cytochrome P-450 catalysed oxidation of acetaminophen, has been generated and studied by pulse radiolysis. In the absence of other reactive solutes, the radical decays rapidly by second order kinetics with a rate constant (2k 2 ) of (2.2 ± 0.4) x 10 9 M -1 sec -1 . In alkaline solutions the radical deprotonates with a pK of 11.1 ± 0.1 to form a radical-anion. The acetaminophen radical-anion reacts with resorcinol at high pH values, leading to the formation of a transient equilibrium from which the one-electron reduction potential of the semi-iminoquinone radical of acetaminophen is estimated to be + 0.707 ± 0.01 V at pH 7. This value predicts that acetaminophen should be oxidised by thiyl radicals. This was confirmed by pulse radiolysis experiments for reaction of the cysteinyl radical, for which rate constants of 7 x 10 6 M -1 sec -1 at pH7 and 2.7 x 10 8 M -1 sec -1 at pH 11.3 were obtained. The reaction of O 2 with the acetaminophen semi-iminoquinone radical could not be detected by pulse radiolysis, and alternative mechanisms for superoxide radical formation are discussed. (author)

Properties of the radicals formed by one-electron oxidation of acetaminophen - a pulse radiolysis study

Energy Technology Data Exchange (ETDEWEB)

Bisby, R H; Tabassum, N

1988-07-15

The semi-iminoquinone radical of acetaminophen, which has previously been proposed as a possible hepatotoxic intermediate in the cytochrome P-450 catalysed oxidation of acetaminophen, has been generated and studied by pulse radiolysis. In the absence of other reactive solutes, the radical decays rapidly by second order kinetics with a rate constant (2k/sub 2/) of (2.2 +- 0.4) x 10/sup 9/ M/sup -1/ sec/sup -1/. In alkaline solutions the radical deprotonates with a pK of 11.1 +- 0.1 to form a radical-anion. The acetaminophen radical-anion reacts with resorcinol at high pH values, leading to the formation of a transient equilibrium from which the one-electron reduction potential of the semi-iminoquinone radical of acetaminophen is estimated to be + 0.707 +- 0.01 V at pH 7. This value predicts that acetaminophen should be oxidised by thiyl radicals. This was confirmed by pulse radiolysis experiments for reaction of the cysteinyl radical, for which rate constants of 7 x 10/sup 6/ M/sup -1/ sec/sup -1/ at pH7 and 2.7 x 10/sup 8/ M/sup -1/ sec/sup -1/ at pH 11.3 were obtained. The reaction of O/sub 2/ with the acetaminophen semi-iminoquinone radical could not be detected by pulse radiolysis, and alternative mechanisms for superoxide radical formation are discussed.

Heavy water radiolysis and chemistry control of the Fugen Nuclear Power Station

International Nuclear Information System (INIS)

Ibuki, Y.; Kitabata, T.; Kato, T.

1989-01-01

A computer analysis for heavy water radiolysis clarified the mechanism of the heavy water radiolysis rate change with impurities in the heavy water and cover gas, helium. The mechanism is supported by over ten years' operational data of the heavy water radiolysis in the Fugen nuclear power station. (author)

The effect of dissolved oxygen on water radiolysis behaviour

International Nuclear Information System (INIS)

Yakabuskie, P.A.; Joseph, J.M.; Wren, J.C.; Stuart, C.R.

2012-09-01

A quantitative understanding of the chemical or redox environments generated in water by ionizing radiation is important for material selection, development of maintenance programs, and safety assessments for water-cooled nuclear power reactors. The highly reactive radicals (·OH, ·H, ·e aq - , ·HO 2 , and ·O 2 - ) and molecular species (H 2 and H 2 O 2 ) generated by water radiolysis can compete in reactions with other dissolved compounds and impose changes to the system chemistry by altering the steady-state concentrations of water radiolysis products, which could impact the degradation of materials in contact with the aqueous phase. Understanding in detail how a given chemical additive changes the long-term radiolysis kinetics can help us to determine what chemistry control steps may be required to return the system to an optimal redox condition, and in turn, enhance the lifetime of reactor components. This study outlines the effect of dissolved oxygen gas, which could be introduced due to air ingress, on long-term water radiolysis behaviour. The effects of solution pH and initial dissolved O 2 concentration on the radiolytic production of molecular H 2 and H 2 O 2 have been investigated by performing experiments with three different O 2 concentrations at pH 6.0 and 10.6 under steady-state radiolysis conditions. The aqueous and gas phase analyses were performed using UV-Vis spectrophotometry and gas-chromatography equipped with electron capture and thermal conductivity detectors. The experimental results were compared with kinetic model calculations of steady-state radiolysis and were found to be in good agreement. The concentrations of water radiolysis products, H 2 O 2 and H 2 , were found to increase in the presence of dissolved oxygen, but the degree of increase was shown to depend on the solution pH. Furthermore, the steady-state concentration of H 2 did not increase as greatly as that of H 2 O 2 at either pH studied. The kinetic analyses have shown

IL 14: Radiolysis of water confined in nano-porous materials

International Nuclear Information System (INIS)

Renault, J.P.; Pommeret, S.; Musat, R.; Le Caer, S.; Alam, M.; Mialocq, J.C.

2010-01-01

Radiolysis of water in nano-porous media has raised a lot of interest and involved research in the recent years, with respect to concerns arising from the storage of nuclear waste. In the civil nuclear industry, storing for a long time nuclear wastes requires safety evaluations in order to test the durability of the materials involved. Among these materials, concrete and clays are a complex heterogeneous material that traps important quantities of interstitial water. Irradiation that arises from the nuclear wastes stored in these materials may lead to the radiolysis of the interstitial water, and the formation of radiolytic products, such as H 2 , O 2 or H 2 O 2 that may cause the breaking or the corrosion of the confining matrix. This communication will describe the possible impacts of confinement on the radiolysis of water. We will especially discuss the current knowledge about the evolution of radiolytic yields of primary species (hydroxyl radical, dihydrogen, aqueous electron) as a function of the degree of confinement and of the nature of the confining material. SEM picture of a nano-porous gold sample used to study the radiolysis of confined water The yield enhancement observed in many cases revealed original energy and charge transfer phenomena that we tried to decipher. (authors)

Specificities of reactor coolant pumps units with lead and lead-bismuth coolant

International Nuclear Information System (INIS)

Beznosov, A.V.; Anotonenkov, M.A.; Bokov, P.A.; Baranova, V.S.; Kustov, M.S.

2009-01-01

The analysis results of impact of lead and lead-bismuth coolants specific properties on the coolants flow features in flow channels of the main and auxiliary circulating pumps are presented. Impossibility of cavitation initiation in flow channels of vane pumps pumping lead and lead-bismuth coolants was demonstrated. The experimental research results of discontinuity of heavy liquid metal coolant column were presented and conditions of gas cavitation initiation in coolant flow were discussed. Invalidity of traditional calculation methods of water and sodium coolants circulation pumps calculations for lead and lead-bismuth coolants circulation pumps was substantiated [ru

Radiolysis of actinides and technetium in alkaline media

Energy Technology Data Exchange (ETDEWEB)

Delegard, C.H., Westinghouse Hanford

1996-07-10

The {gamma}-radiolysis of aerated alkaline aqueous solutions of Np(V), Np(VI), Pu(VI), Tc(IV), Tc(V), and TC(VII) was studied in the absence of additives and in the presence of CO{sub 3}{sup 2-}, NO{sub 3}{sup -}, NO{sub 2}{sup -}, EDTA, formate, and other organic compounds. The radiolytic reduction of Np(V), Np(VI), Pu(VI), and TC(VII) under different experimental conditions was examined in detail. The addition of EDTA, formate, and alcohols was found to considerably increase the radiation-chemical reduction yields. The formation of the Np(V) peroxo complex was observed in the {gamma}-radiolysis of alkaline aqueous solutions of Np (VI) in the presence of nitrate.

Development of subpicosecond pulse radiolysis system

CERN Document Server

Kozawa, T; Miki, M; Yamamoto, T; Suemine, S; Yoshida, Y; Tagawa, S

2000-01-01

The highest time resolution of the pulse radiolysis had remained about 30 ps since the late 1960s. To make clear the primary processes in the radiation chemistry and physics within 30 ps, we developed a stroboscopic pulse radiolysis system for the absorption spectroscopy with the time resolution of 2.0 ps (10-90% rise time). The time resolution of 2.0 ps was estimated from the time-dependent behavior of the hydrated electrons. The system consists of a subpicosecond electron linac as an irradiation source, a femtosecond laser as an analyzing light and a jitter compensation system.

A study of solute transport of radiolysis products in crud and its effects on crud growth on PWR fuel pin

Energy Technology Data Exchange (ETDEWEB)

Joe, Justin H. [BNF Consulting (United States); Kim, Seung Jun, E-mail: skim@lanl.gov [Mechanical and Thermal Engineering Group (AET-1), Los Alamos National Laboratory (United States); Jones, Barclay G. [Department of Nuclear Plasma Radiological Engineering, University of Illinois Urbana-Champaign (United States)

2016-04-15

Highlights: • We model a 3-D numerical solute transport within crud deposit on PWR fuel pin. • Source term effect from radiolysis yield and recombination is minimal. • Lower crud porosity leads substantially higher concentration of solutes. • Thicker crud deposit generates substantially higher concentration of solutes. • High concentration of radiolysis species (H{sub 2}, O{sub 2}, and H{sub 2}O{sub 2}) can be directly related to corrosion issues on fuel cladding. - Abstract: This research examines the concentration of radiolysis species (H{sub 2}, O{sub 2}, and H{sub 2}O{sub 2}) over the porous crud layer using a three dimensional time dependent solute transport model. A Monte Carlo random walk technique is adopted to simulate the transport behavior of the different species with various parametric studies of source term, crud thickness, and crud porosity. Particularly, this model employs a system of coupled mass transport and chemical interactions as the source term, which makes the problem non-linear. It is demonstrated that a negligible effect on radiolysis species concentrations change due to the consideration of source term. The crud thickness and porosity effect on the concentration distributions are notably observed. In general, higher concentration starts from the intersection of the heating surface with the chimney wall from the beginning and it reaches the equilibrium state within tens of seconds. The concentration profiles of the radiolysis species H{sub 2}, O{sub 2}, and H{sub 2}O{sub 2} can be directly related to corrosion issues. The direct application of this study to nuclear engineering research is to aid in the design of reactors with higher performance without experiencing an Axial Offset Anomaly (AOA), an unexpected measured shift in axial power distribution from predicted values.

A study of solute transport of radiolysis products in crud and its effects on crud growth on PWR fuel pin

International Nuclear Information System (INIS)

Joe, Justin H.; Kim, Seung Jun; Jones, Barclay G.

2016-01-01

Highlights: • We model a 3-D numerical solute transport within crud deposit on PWR fuel pin. • Source term effect from radiolysis yield and recombination is minimal. • Lower crud porosity leads substantially higher concentration of solutes. • Thicker crud deposit generates substantially higher concentration of solutes. • High concentration of radiolysis species (H 2 , O 2 , and H 2 O 2 ) can be directly related to corrosion issues on fuel cladding. - Abstract: This research examines the concentration of radiolysis species (H 2 , O 2 , and H 2 O 2 ) over the porous crud layer using a three dimensional time dependent solute transport model. A Monte Carlo random walk technique is adopted to simulate the transport behavior of the different species with various parametric studies of source term, crud thickness, and crud porosity. Particularly, this model employs a system of coupled mass transport and chemical interactions as the source term, which makes the problem non-linear. It is demonstrated that a negligible effect on radiolysis species concentrations change due to the consideration of source term. The crud thickness and porosity effect on the concentration distributions are notably observed. In general, higher concentration starts from the intersection of the heating surface with the chimney wall from the beginning and it reaches the equilibrium state within tens of seconds. The concentration profiles of the radiolysis species H 2 , O 2 , and H 2 O 2 can be directly related to corrosion issues. The direct application of this study to nuclear engineering research is to aid in the design of reactors with higher performance without experiencing an Axial Offset Anomaly (AOA), an unexpected measured shift in axial power distribution from predicted values.

An overview of radiolysis studies for the molten salt reactor remediation project

International Nuclear Information System (INIS)

Icenhour, A.S.; Williams, D.F.; Trowbridge, L.D.; Toth, L.M.; Del Cul, G.D.

2001-01-01

A number of radiolysis experiments have been performed in support of the remediation of the Molten Salt Reactor Experiment (MSRE)at the Oak Ridge National Laboratory.Materials studied included simulated MSRE fuel salt,fluorinated charcoal, NH 4 F,2NaFUF 6 ,UO 2 F 2 uranium oxides with a known residual fluoride content,and uranium oxides with a known moisture content.The results from these studies were used as part of the basis for the interim or long-term storage of materials removed from the MSRE. (author)

Gamma-radiolysis of aqueous solutions of methyl orange and chrysoidine

International Nuclear Information System (INIS)

Khabarov, V.N.; Kozlov, L.L.; Panchenkov, G.M.

1980-01-01

Radiation-chemical bleaching of azo dyes of methyl orange and chrysoidine in aqueous and aqueous-alcoholic solutions under the effect of γ-radiation of 60 Co is studied. The effect of different additions and pH value of medium upon radiolysis of azo dyes is investigated. Radiation-chemical yields of the bleaching are determined. Quantitative connection between the initial yields of water radiolysis products and radiation yields of the bleaching of azo dyes is established. On the basis of the results obtained the most probable mechanism of methyl orange and chrysoidine bleaching is suggested

Formation and role of excited states in radiolysis - a foreword

International Nuclear Information System (INIS)

Singh, A.

1976-01-01

It is stated that the choice of contributions to the special issue of this Journal has been limited to those which bear on the details of the mechanisms of excited state formation and are likely to be useful to radiation chemists. Since more than half the energy deposited in radiolysis goes into excitation, studies on the fate of the excited species formed are very important. A brief reference is made to the subject matter of each of the fifteen contributions, and its significance to the development of the technique of radiolysis is outlined. (U.K.)

Pulse radiolysis studies of iron(I) in aqueous solutions

International Nuclear Information System (INIS)

Nenadovic, M.T.; Micic, O.I.; Muk, A.A.

1980-01-01

The absorption spectrum and decay kinetics of the products of the reactions of iron(II) ions with hydrated electrons and hydrogen atoms have been studied in aqueous solution using pulse-radiolysis techniques. Iron(I) is formed by reaction with hydrated electrons and its absorption spectrum is reported and discussed. The formation of molecular hydrogen by reaction of Fe + with water is suppressed by other solutes present in the solutions. In acidic solutions containing [SO 4 ] 2- , the intermediates formed in the reaction with H atoms decay by a first-order process and produce molecular hydrogen, but the rate of their decay does not depend only on the oxonium ion concentration but also on intermolecular rearrangement in the [FeSO 4 -H] complex. (author)

One-electron reduction of anthraquinone sulphonates: a pulse radiolysis study

International Nuclear Information System (INIS)

Pal, H.; Palit, D.K.; Mukherjee, T.; Mittal, J.P.

1991-01-01

Semiquinone free radicals, derived from 2-sulphonate, 1,5-disulphonate and 2,6-disulphonate derivatives of 9,10-anthraquinone, have been studied using pulse radiolysis and kinetic absorption spectrophotometry techniques. Spectroscopic characteristics of both neutral and anionic species have been ascertained. Kinetics of formation and decay, reactivity with oxygen and one-electron reduction potential values have been estimated. The semiquinone radicals have been shown to be very stable under suitable pH conditions where the equilibrium (2 semiquinone ↔ quinone + hydroquinone) lies predominantly to the left. From a measurement of the equilibrium constants at different pH, values of E 2 and E m have been calculated. (author)

Pulse radiolysis of solutions of trans-stilbene

International Nuclear Information System (INIS)

Langan, J.R.; Salmon, G.A.

1982-01-01

On pulse radiolysis of solutions of trans-stilbene (t-St) in THF the radical-anion of t-St is formed by reaction of e - sub(s) with t-St. The transient absorption spectrum observed with lambdasub(max) at 500 and 720 nm is attributed to the unassociated St - . The subsequent decay of the radical-anion is accounted for by reaction with the counter-cation of THF formed on radiolysis and with radiolytically generated radicals; rate constants for these processes are estimated. Addition of sodium tetrahydridoaluminate (NAH) results in the radical-anion being associated with Na + as a contact ion-pair and a shift of lambdasub(max) to 490 nm. In the presence of the lithium salt the absorption spectrum of the radical-anion reverts to 500 nm. On pulse radiolysis of solutions containing NAH the main reaction forming St - is that of (Na + , e - sub(s))ion pairs with t-St. In addition there is a delayed formation of St - over a period of microseconds. The presence of tetrahydridoaluminate salts also greatly enhances the stability of St - and at high doses per pulse little decay was observed over 700 μs. The variation of G(St - ) with [NAH] was studied and was found to attain a plateau value of 2.0 at the higher concentrations. (author)

Coolant clean-up system in the primary coolant circuit for nuclear reactor

International Nuclear Information System (INIS)

Saito, Michio.

1981-01-01

Purpose: To maintain the quality of coolants at a prescribed level by distillating coolants in the primary coolant circuit for a BWR type reactor to remove impurities therefrom, taking out the condensates from the top of the distillation column and extracting impurities in a concentrated state from the bottom. Constitution: Coolant water for cooling the core is recycled by a recycling pump by way of a recycling pipeway in a reactor. The coolants extracted from an extraction pipeway connected to the recycling pipeway are fed into a distillation column, where distillation is taken place. Impurities in the coolants, that is, in-core corrosion products, fission products generated in the reactor core, etc. are separated by the distillation, concentrated and solidified in the bottom of the distillation column. While on the other hand, condensates removed with the impurities, that is, coolants cleaned-up are recycled to the coolant water for cooling the reactor core. (Moriyama, K.)

Organic coolant for ARIES-III

International Nuclear Information System (INIS)

Sze, D.K.; Sviatoslavsky, I.; Sawan, M.; Gierszewski, P.; Hollies, R.; Sharafat, S.; Herring, S.

1991-04-01

ARIES-III is a D-He 3 reactor design study. It is found that the organic coolant is well suited for the D-He 3 reactor. This paper discusses the unique features of the D-He 3 reactor, and the reason that the organic coolant is compatible with those features. The problems associated with the organic coolant are also discussed. 8 refs., 2 figs., 6 tabs

Pulse radiolysis studies in model lipid systems

International Nuclear Information System (INIS)

Patterson, L.K.; Hasegawa, K.

1978-01-01

The kinetic and spectral behavior of radicals formed by hydroxyl radical attack on linoleate anions has been studied by pulse radiolysis. Reactivity of OH toward this surfactant is an order of magnitude greater in monomeric form (kOH + linoleate = 8.0 x 10 9 M -1 sec -1 ) than in mecellar form (kOH + lin(micelle) = 1.0 x 10 9 M -1 sec -1 ). Abstraction of a hydrogen atom from the doubly allylic position gives rise to an intense absorption in the UV region (lambda max = 282-286 nm, epsilon approximately 3 x 10 4 M -1 cm -1 ) which may be used as a probe of radical activity at that site. This abstraction may occur, to a small extent, directly via OH attack. However, greater than 90% of initial attack occurs at other sites. Subsequent secondary abstraction of doubly allylic H atoms appears to occur predominantly by: (1) intramolecular processes in monomers, (2) intermolecular processes in micelles. Disappearance of radicals by secondary processes is slower in the micellar pseudo phase than in monomeric solution. (orig.) 891 HK 892 KR [de

Pulse radiolysis study of the reduction mechanism of an antitumor antibiotic, mitomycin C

International Nuclear Information System (INIS)

Machtalere, G.; Houee-Levin, C.; Gardes-Albert, M.; Ferradini, C.; Hickel, B.

1988-01-01

Mitomycin C is a quinonic antitumor metabolized in vivo by one-electron reduction. We have studied the mechanism of the one-electron reduction of this drug by pulse radiolysis using C00 .- free radicals as reductants. Semiquinonic and hydroquinonic intermediates are formed. The hydroquinonic form undergoes a methanol elimination leading to a transient which can disappear in one of two ways: by either internal redox reaction or hydrolysis of the aziridine. 17 refs [fr

Radiolysis of cyanocobalamin (vitamin B{sub 12})

Energy Technology Data Exchange (ETDEWEB)

Juanchi, X.; Albarran, G.; Negron-Mendoza, A

2000-03-01

Research on the radiolysis of vitamins is of considerable interest since these compounds are important nutritional constituents in foods and in dietetic supplements. In spite of these considerations there are few data and very often difficult to compare for the radiolytic behavior of vitamins. In this work we focused our attention on to the study of the radiolysis of cyanocobalamin (vitamin B{sub 12}) in solid state and in aqueous solutions. The procedure was followed by HPLC and UV-spectroscopy. The results obtained in aqueous solutions showed a dependence of the decomposition as a linear function of the dose. The G of decomposition for a 1x10{sup -5} M solution was 3.3. In the solid state the vitamin was very stable towards the irradiation in the conditions used in this study with a G=2.1x10{sup -3}. A study made with Serratia marcescens as a microbiological contaminant showed that at the sterilization dose there is a destruction of the vitamin in aqueous solution. In the solid state the degree of decomposition was 7%. (author)

The fate of primary cations in radiolysis of alkanes as studied by ESR

International Nuclear Information System (INIS)

Iwasaki, M.; Toriyama, K.; Nunome, K.

1983-01-01

The structures and reactions of alkane cations (RH + ) have been studied by ESR to elucidate the fate of primary cations in radiolysis of alkanes. Radical cations of prototype alkanes such as C 2 H 6 , C 3 H 8 , iso-C 4 H 10 and neo-C 5 H 12 etc. as well as their partially deuterated analogues were stabilized in irradiated frozen matrices such as SF 6 , CFCl 2 CF 2 Cl and CFCl 3 having a higher ionization potential than that of these alkanes contained as dilute solutes. RH + in SF 6 and in CFCl 2 CF 2 Cl converts into alkyl radicals by deprotonation probably through bimolecular reactions, whereas RH + in CFCl 3 unimolecularily decomposes into olefinic cations by H 2 and/or CH 4 elimination reactions. It is further found that the electronic structures of propane and isobutane cations in halocarbon matrices are different from those in SF 6 and the difference is drastically reflected in the site preference of their deprotonation reactions. The results are discussed in relation to the mechanisms of pairwise formation of alkyl radicals in low temperature radiolysis of neat alkanes and its suppression by addition of electron scavengers. (author)

Formation of carbonyl compounds in radiolysis of ethylene glycol in methanol

International Nuclear Information System (INIS)

Bezborodova, S.G.; Vetrov, V.S.; Kalyazin, E.P.; Korolev, V.M.; Salamatov, I.I.

1977-01-01

Radiolysis of diluted solutions of ethylene glycol has been investigated. It is shown that acetaldehyde, glycol aldehyde and formaldehyde are the main products of radiolysis of methanol solutions of ethylene glycol. Acetaldehyde and glycol aldehyde yields increase in radiolysis of methanol solutions of ethylene glycol with an increase of the original concentration of ethylene glycol and a temperature rise of radiolysis. Formaldehyde yields increase with the ethylene glycol concentration but decrease with a temperature rise (the formation of formaldehyde from methanol is taken into account). A mechanism of radiation-chemical transformations of ethylene glycol in methanol is explained. It is concluded that the main directions of ethylene glycol decomposition, detected in water solutions of ethylene glycol, are also realized in methanol solutions. However, a role of different directions of decomposition depends on the medium

Reaction mechanisms in the radiolysis of peptides, polypeptides and proteins

International Nuclear Information System (INIS)

Garrison, W.M.

1985-01-01

The purpose of this review is to bring together and to correlate the wide variety of experimental studies that provide information on the reaction products and reaction mechanisms involved in the radiolysis of peptides, polypeptides and proteins (including chromosomal proteins) in both aqueous and solid-state systems. The comparative radiation chemistry of these systems is developed in terms of specific reactions of the peptide main-chain and the aliphatic, aromatic-unsaturated and sulfur-containing side-chains. Information obtained with the various experimental techniques of product analysis, competition kinetics, spin-trapping, pulse radiolysis and ESR spectroscopy is included. 147 refs

Reaction mechanisms in the radiolysis of peptides, polypeptides and proteins

Energy Technology Data Exchange (ETDEWEB)

Garrison, W.M.

1985-01-01

The purpose of this review is to bring together and to correlate the wide variety of experimental studies that provide information on the reaction products and reaction mechanisms involved in the radiolysis of peptides, polypeptides and proteins (including chromosomal proteins) in both aqueous and solid-state systems. The comparative radiation chemistry of these systems is developed in terms of specific reactions of the peptide main-chain and the aliphatic, aromatic-unsaturated and sulfur-containing side-chains. Information obtained with the various experimental techniques of product analysis, competition kinetics, spin-trapping, pulse radiolysis and ESR spectroscopy is included. 147 refs.

Nuclear magnetic resonance in pulse radiolysis. Chemically induced dynamic nuclear polarization

International Nuclear Information System (INIS)

Trifunac, A.D.; Johnson, K.W.; Lowers, R.H.

1976-01-01

Nuclear magnetic resonance and chemically induced dynamic nuclear polarization (CIDNP) were applied to the study of pulse radiolysis. Samples were irradiated with a 3-MeV electron beam from the Argonne Van de Graaff accelerator in an EPR magnet (approximately 4000 G) which had axial holes for beam access. A fast flow system transferred the irradiated solution to the rotating 5-mm NMR sample tube. The NMR spectra of mixtures of sodium acetate and methanol were presented to demonstrate the features of the CIDNP in pulse radiolysis

Radiolysis of groundwater in a repository for spent fuel - a literature survey

International Nuclear Information System (INIS)

Snellman, Margit

1989-06-01

This review on radiolysis considers both the fundamental mechanisms and theory involved in radiolysis of pure water and systems containing major species existing in repository conditions. The amount of different molecules and radicals formed in radiolysis of water is a complex function of the type of radiation and dose rate, pH and ionic strength of water. The principal effects of the species present in water are to scavenge the radiolytic intermediates and products producing new species and changing the yield of radical and molecular products. Of the metals (Cu, Fe) and inorganic ions (Cl - , HCO 3 - /CO 3 2- , NH 3 /NO 2 - ) considered, iron is the most important one and can participate in a number of reactions both with the primary and secondary radiolysis products and may effect both the H 2 and H 2 O 2 yield. For the estimation of the overall effect of radiolysis in the repository both calculations and supporting experimental work is needed

Structural analysis of radiolysis products of sennoside

International Nuclear Information System (INIS)

Song, Hyun Pa; Kim, Dong Ho

2011-01-01

The purpose of the present investigation was to analyze the structural changes of gamma irradiated sennoside B (prodrug) and to provide the possibility for application of irradiation to induce structural changes of the prodrugs for enhanced bioavailability. Sennoside B (200 ppm) in 70% methanol solution with or without the use of hydrogen peroxide or nitrous oxide gas was irradiated with 1, 3, 5, 10 and 20 kGy by gamma ray. The radiolysis products of gamma irradiated sennoside B solution were identified and determined by TLC, HPLC and LC-MS/MS. The sennoside B quantity decreased when irradiation dose increased and completely degraded at 10 kGy of irradiation. There was a linear relationship between the production of the radiolysis compounds and the absorbed dose of the gamma ray irradiated sennoside B. Radiolysis products yields increased on the addition of nitrous oxide gas into the sennoside B solution. No anthraquinone compounds were formed after irradiation of sennosie B. Scission of the O-glycoside bond and consequently formation of aglycone of sennoside B was observed

Structural analysis of radiolysis products of sennoside

Energy Technology Data Exchange (ETDEWEB)

Song, Hyun Pa; Kim, Dong Ho [KAERI, Daejeon (Korea, Republic of)

2011-01-15

The purpose of the present investigation was to analyze the structural changes of gamma irradiated sennoside B (prodrug) and to provide the possibility for application of irradiation to induce structural changes of the prodrugs for enhanced bioavailability. Sennoside B (200 ppm) in 70% methanol solution with or without the use of hydrogen peroxide or nitrous oxide gas was irradiated with 1, 3, 5, 10 and 20 kGy by gamma ray. The radiolysis products of gamma irradiated sennoside B solution were identified and determined by TLC, HPLC and LC-MS/MS. The sennoside B quantity decreased when irradiation dose increased and completely degraded at 10 kGy of irradiation. There was a linear relationship between the production of the radiolysis compounds and the absorbed dose of the gamma ray irradiated sennoside B. Radiolysis products yields increased on the addition of nitrous oxide gas into the sennoside B solution. No anthraquinone compounds were formed after irradiation of sennosie B. Scission of the O-glycoside bond and consequently formation of aglycone of sennoside B was observed

Computer modeling of inhibition of α-radiolysis of water by H2 addition (9. International Workshop on Radiolysis, Electrochemistry and Materials Performance)

International Nuclear Information System (INIS)

Lertnaisat, Phantira; Katsumura, Yosuke; Mukai, Satoru; Umehara, Ryuji; Shimizu, Yuichi; Suzuki, Masaru

2012-09-01

It is known that α-radiolysis of water produces H 2 gas continuously. The addition of H 2 to water inhibits the water decomposition; H 2 evolution. In order to suppress the water decomposition, 25 cc H 2 STP/kg-H 2 O is added to the coolant water in PWR. However, the exact inhibition mechanism is still not made clear yet. In this project, the chemical kinetic simulation program, so called FASCIMILE, was used to reproduce the suppression of α-radiolysis of water by H 2 addition. By using three important factors; the decomposition (G-value), the reaction set and rate constants, and the dose rate, it is found that without hydrogen addition, the simulation shows the almost linear increase of molecular products; H 2 , H 2 O 2 , and O 2 . Nevertheless, as the additional hydrogen is added to the system, this behaviour of linear increase is shifted to longer time period. And up to certain concentration, the linear increase behaviour is completely suppressed and the molecular products reach the steady state condition at early time period and much lower concentration. The minimum concentration of H 2 which could completely suppress the decomposition of water is called Critical Hydrogen Concentration (CHC) and it is dose rate dependent value. The CHC is found to be dependent on the reaction set and rate constants. The simulation results show that the CHC at room temperature and dose rate of 1 kGy/s of the simulation done by using reaction set and rate constants obtained from Ershov et al. and AECL report 2009 are 165μM and 146 μM, respectively. From the change of the behaviour of molecular products after reaching the CHC, the possible mechanism is proposed. First, the OH radical are formed via the reaction of H + H 2 O 2 → OH + H 2 O and e - aq + H 2 O 2 → OH+OH - . Then OH, which normally will react with H 2 O 2 to produced HO 2 , will react with the additional H 2 , which produce H to continue the chain reaction. The relation of chain reaction to the suppression of

Impact of β- radiolysis and transient products on irradiation-enhanced corrosion of zirconium alloys

International Nuclear Information System (INIS)

Lemaignan, C.

1992-01-01

An analysis has been undertaken of the various cases of local enhancement of the corrosion rate of zirconium alloys under irradiation. It is observed that in most cases a strong emission of energetic β - is present leading to a local energy desorption rate higher than the core average. This suggests that the local transient radiolytic oxidising species produced in the coolant by the β - particles could contribute to corrosion enhancement, by increasing the local corrosion potential. This process is applicable to the local enhanced corrosion found in front of stainless steels structural parts, due to the contribution of Mn, in front of Pt inserts and Cu-rich cruds. It explains also the irradiation corrosion enhancement of Cu-rich Zr alloys. Enhanced corrosion around neutron absorbing material is explained similarly by pair production from conversion of high energy capture photons in the cladding, leading to energetic electrons. The same process was found to be active with other highly ionising species like α in Ni-rich alloys and fission products in homogeneous reactors. This mechanism, applicable for an explanation of localised irradiation-enhanced corrosion, is proposed to be extended to the reactor core, where the general enhancement of Zr-alloy corrosion under irradiation would be due to the general radiolysis. It suggests that care should be taken to avoid any source of β - emission or other ionising species in the reactor core that could give an increase of energy deposition rate for radiolysis. Also the corrosion testing conditions for the materials to be used in reactors have to be relevant to the radiolytic environments found in the reactor cores. (orig.)

Radiolysis of solutions in anthraquinone derivatives

International Nuclear Information System (INIS)

Kriminskaya, Z.K.

1996-01-01

Stationary radiolysis of anthraquinones in solutions of ethanol, propanol-2 and water by gamma-radiation (dose rate of 1.6 Gy/s) is studied. It is shown that anthraquinones are reduced in the above solutions up to anthrahydroquinones, whereby all reduction particles participate in the reduction process. The reverse process of the post-radiation oxidation of anthrahydroquinones up to anthraquinones is a radical process

Pulse radiolysis

International Nuclear Information System (INIS)

Greenshields, H.; Seddon, W.A.

1982-03-01

This supplement to two bibliographies published in 1970 and 1972 lists 734 references to the literature of pulse radiolysis, arranged under eight broad subject headings. The references were compiled by searching Biological Abstracts, Chemical Abstracts, Nuclear Science Abstracts and the Weekly List of Papers in Radiation Chemistry issued by the Radiation Chemistry Data Center of Notre Dame University. Full bibliographic data is given for papers published in the period 1971 to 1974. A personal author index listing more than 600 authors and a similar number of co-authors is included

Formation and properties of radiation-induced defects and radiolysis products in lithium orthosilicate

Energy Technology Data Exchange (ETDEWEB)

Tiliks, J.E.; Kizane, G.K.; Supe, A.A.; Abramenkovs, A.A.; Tiliks, J.J. (Latvian Univ., Riga (Latvia)); Vasiljev, V.G. (Acad. A.A. Bochvar Inst. of Inorganic Materials, Moscow (USSR))

1991-12-01

Formation and properties of radiation-induced defects and radiolysis products in polycrystalline powders and ceramic pellets of Li{sub 4}SiO{sub 4} were studied under the effect of various types of ionizing irradiation ({gamma} quants, accelerated electrons, reactor irradiation), humidity, temperature, impurities in the samples, etc. The content of radiation defects and radiolysis products poorly depends on irradiation type, dose rate, admixture elements. The concentration of defects highly depends on the temperature of irradiation, humidity, granural size. Empirical dependence of radiolysis degree {alpha} on the dose was found: {alpha}=5x10{sup -2}xD{sup 0.5} for {gamma} and electron irradiation (T{sub rad}=300-350 K) and {alpha}=5x10{sup -3}xD{sup 0.5} for reactor radiation (T{sub rad}=700-800 K); {alpha} - matrix dissociation degree (in %); D - dose (in MGy). Colloidal lithium and silicon, lithium and silicon oxides, and O{sub 2} are the final products of radiolysis. Radiation-induced defects change tritium thermo-extraction parameters, deteriorate mechanical, thermo-physical and electric properties of ceramics. (orig.).

Study of the selective abstration reaction of the hydrogen atom in the radiolysis and photolysis of alkane mixture at 77 K

International Nuclear Information System (INIS)

Guedes, S.M.L.

1979-01-01

The occurence of the selective abstraction reaction of the solute hydrogen atom by hydrogen atom produced during radiolysis or photolysis of the systems such as neopentane/cyclo-hexane/HI, neopentane/2,3 dimethylbutane, n-pentane/HI/cyclo-hexane and cyclo-hexane/HI/n-pentane, at 77 K is studied. Experiments have been undertaken on the kinetics nature of the active species, the H atom, during radiolysis and photolysis of the neopentane/cyclo-hexane/HI system at 77 K, presenting competitive reactions. Studies have also been made on the occurrence of the selective abstraction reaction in inverted systems, in which the concentrations of the components of a system are so much altered that the solute becomes the solvent and vice-versa, in the other system. By means of photolysis at 77 K, it has been observed that for the two systems constitued by the cyclo-hexane and n-pentane the selective abstraction reaction occurs. However, for radiolysis of that same two systems it has been observed that only the hydrogen atom abstraction reaction corresponding to the solvent occurs. (Author) [pt

A computerized pulse radiolysis system

International Nuclear Information System (INIS)

Eriksen, T.E.; Lind, J.; Reitberger, T.

1976-01-01

A computer based pulse radiolysis system for gathering and handling of transient optical absorption and electric conductivity data is presented. The system has been developed around a Biomation 8100 transient recorder and a PDP 11/40 (Digital Equipment Corp) computer. (author)

Radiolysis of starch

International Nuclear Information System (INIS)

Raffi, J.; Saint-Lebe, L.; Berger, G.

1978-01-01

In the first part of the paper the results of work on the identification and determination of the gamma ( 60 Co) radiolysis products of maize starch are brought together and, wherever possible, a balance drawn up by chemical class. The second part of the paper deals with the main parameters governing radiolysis: dose, irradiation temperature and atmosphere, water content and the conditions under which the irradiated starch is stored. The third part, devoted to the mechanisms believed to be involved, contains the following conclusions: (a) the formation of radiation-induced products with a carbon skeleton probably results from a breaking of the -C-O-C- chains with rearrangement of the radicals and/or a reaction involving the water and the oxygen - the oxygen has an activating effect which does not fundamentally modify the mechanism, whereas the effect of the water is more complex and varies according to the product; (b) the formation of hydrogen peroxide probably implies the addition of atmospheric oxygen to the radiation-induced hydrogen atoms in the water or to the organic radicals obtained by abstraction of a hydrogen from the starch. Lastly, the different methods envisaged for confirming or improving the mechanistic hypotheses are discussed. (author)

Study on radiolysis products of N,N,N',N'-tetrabutyl-3-oxa-pentanediamide. Pt.1: Qualitative and quantitative analysis of dibutylamine

International Nuclear Information System (INIS)

Zhang Xiaolan; Shanghai Univ., Shanghai; Bao Borong; Shanghai Univ., Shanghai; Yang Yanqin; Ye Guoan; Zhang Xianye

2005-01-01

The study on radiolysis products of gamma-irradiated N,N,N',N'-tetrabutyl-3-oxa-pentane-diamide (TBOPDA) is very useful towards the extractant stability. IR and headspace solid-phase microextraction combined with gas chromatography/mass spectrometry (SPME-GC/MS) are used in the research. By comparisons with standard substances, dibutylamine and N,N-dibutylformamide are comfirmed to be the major radiolysis products. The influences of irradiation on TBOPDA and dibutylamine are quantitated by using headspace SPME-GC and HPLC. According to the experiment results, the possible ways of degradation are also proposed. (authors)

Coolant leakage detection device

International Nuclear Information System (INIS)

Ito, Takao.

1983-01-01

Purpose: To surely detect the coolant leakage at a time when the leakage amount is still low in the intra-reactor inlet pipeway of FBR type reactor. Constitution: Outside of the intra-reactor inlet piping for introducing coolants at low temperature into a reactor core, an outer closure pipe is furnished. The upper end of the outer closure pipe opens above the liquid level of the coolants in the reactor, and a thermocouple is inserted to the opening of the upper end. In such a structure, if the coolants in the in-reactor piping should leak to the outer closure pipe, coolants over-flows from the opening thereof, at which the thermocouple detects the temperature of the coolants at a low temperature, thereby enabling to detect the leakage of the coolants at a time when it is still low. (Kamimura, M.)

A Study on thermal-hydraulic characteristics of the coolant materials for the transmutation reactor

Energy Technology Data Exchange (ETDEWEB)

Chung, Chang Hyun; You, Young Woo; Cho, Jae Seon; Kim, Ju Youl; Kim, Do Hyoung; Kim, Yoon Ik; Yang, Hui Chang [Seoul National University, Taejon (Korea)

1998-03-01

The objective of this study is to provide the direction of transmutation reactor design in terms of thermal hydraulics especially through the analysis of thermal hydraulic characteristics of various candidate materials for the transmutation reactor coolant. In this study, the characteristics of coolant materials used in current nuclear power plants and candidate materials for transmutation reactor are analyzed and compared. To evaluate the thermal hydraulic characteristics, the preliminary thermal-hydraulic calculation is performed for the candidate coolant materials of transmutation reactor. An analysis of thermal-hydraulic characteristics of transmutation reactor. An analysis of thermal-hydraulic characteristics of Sodium, Lead, Lead-Bismuth, and Lead-Lithium among the liquid metals considered as the coolant of transmutation reactor is performed by using computational fluid dynamics code FLUENT, and SIMPLER algorithm. (author). 50 refs., 40 figs., 30 tabs.

Research on Coolant Radiochemistry

International Nuclear Information System (INIS)

Ha, Yeong Keong; Kim, W. H.; Yeon, J. W.; Jung, Y. J.; Choi, K. C.; Choi, K. S.; Park, Y. J.; Cho, Y. H.

2007-06-01

The final objective of this study is to develop a method for reducing radioactive materials formed in the reactor coolant circuit. This second stage research was categorized into the following three subgroups: the development of the estimation technique of microscopic chemical variation at high temperatures and pressures, the fundamental study on the thermodynamics at high temperatures and pressures, and the study on the deposition of metal oxides and the determination of the main factors responsible for the growth of CRUD. First, in the development of the estimation technique of microscopic chemical change at high temperatures and pressures, the technique for measuring coolant chemistry such as pH, conductivity and Eh was developed to be appropriate for the high temperature and pressure condition. The coolant chemistry measuring system including the self-devised high temperature pH sensor can be applied to the field of nuclear reactor and contribute on a large scale in the automation of the coolant chemistry control and the establishment of the real-time on-line measuring technique. Secondly, the dissociation constant of water and the solubility of metal oxides were measured in the fundamental study on the thermodynamics at high temperatures and pressures. Finally, in the study on the deposition of metal oxides and the determination of the main factors responsible for the growth of CRUD, the careful investigation of the deposition phenomena of micro particles on the cladding surface showed that subcooled boiling and the dissolved hydrogen are the main factors responsible for the growth of CRUD. In addition, the basis was provided for the construction of a new particle behavior model in the reactor coolant circuit

Radiolysis of carbohydrates as studied by ESR and spin-trapping—II. Glycerol- d8 xylitol, dulcitol, d-sorbitol and d-mannitol

Science.gov (United States)

Kuwabara, M.; Zhang, Z.-Y.; Inanami, O.; Yoshii, G.

Studies concerning the radicals produced in glycerol by reactions with OH radicals have been carried out by investigating deuterated glycerol (glycerol-d 8) by spin-trapping with 2-methyl-2-nitrosopropane. Free radicals produced in linear carbohydrates such as xylitol, dulcitol, D-sorbitol and D-mannitol by reactions with OH radicals as well as by direct γ-radiolysis have been also investigated by spin-trapping. The ESR spectra of the spin-trapped radicals were analysed on the basis of the results from ESR and spin-trapping experiments on glycerol and deuterated glycerol, and the formation of three radical species, CHO-CH-, CH 2-CO- and HO-CH-, due to both OH reactions and direct γ-radiolysis was confirmed for all compounds. The presence of a radical, -CO-CH-, was detected for xylitol, D-sorbitol and D-mannitol. General reactions processes induced by OH reactions or γ-radiolysis in the solid state are discussed.

Radiolysis of polytetrafluoroethylene

International Nuclear Information System (INIS)

Ferreira, Max Passos; Ferreira, Roberta Viana; Verly, Rodrigo Moreira

2007-01-01

Polytetrafluoroethylene is a linear polymer with structure: -[-CF 2 -CF 2 -] n -. Due to its singular properties, it is ideal for use at high temperatures and in chemically aggressive environments. It is extremely sensitive to ionizing radiation and is quickly degraded. PTFE radiolysis has been extensively studied. However, despite the many published papers, its degradation mechanism remains much uncertain. The degradation of polytetrafluoroethylene by γ irradiation yields perfluorinated carboxylic acids, olefin mixtures, and paraffins with different molecular weights. This process is a new alternative for the synthesis of aliphatic perfluorinated compounds used as intermediates for obtaining special products such as fluoro surfactants, electrical materials, special products for the textile industry, etc. PTFE scraps were irradiated with a uniform source of 60 Co gamma rays in oxygen atmosphere with a dose of 3 MGy. The radiolysis of PTFE yielded a water soluble material (probably fluorinated hydrocarbons with low molecular weight and main chains with 10-20 carbon atoms) and a water insoluble brittle polymeric material. Spectroscopy analysis in the infrared region of irradiated and non-irradiated PTFE were carried out. X-ray diffractometry pointed to changes in the crystalline structure of PTFE; scanning electron microscopy indicated alterations in samples irradiated under different conditions. Mass spectrometry was also used to identify the compounds formed after sample irradiation. Comparison of irradiated and non-irradiated FTIR spectra showed the formation of bands at 3450 cm -1 , associated with the O-H stretching, and at 1631 cm -1 , associated with the C=O stretching. The bands are characteristic of carboxylic acid, which indicates its formation in irradiated PTFE. (author)

Radiolysis and corrosion aspects of the aqueous self-cooled blanket concept

International Nuclear Information System (INIS)

Bruggeman, A.; Snykers, M.; Bogaerts, W.F.; Waeben, R.; Embrechts, M.J.; Steiner, D.

1989-01-01

Corrosion and radiolysis aspects of the Aqueous Self-Cooled Blanket concept, proposed as a potential shielding breeding blanket for near term fusion devices and fusion reactors, have been investigated. On the basis of preliminary results for selected aqueous solutions of lithium compounds, no particular corrosion problems have been revealed for the low-temperature concept envisaged for NET and radiolysis effects might be controlled by appropriate countermeasures. For the reactor-relevant high-temperature concept particular attention has to be paid to intergranular stress-corrosion and to the synergistic radiolysis-corrosion effects. Further information is needed from tests performed in relevant operational conditions. (orig.)

A pulse radiolysis study of emulsion polymerization

International Nuclear Information System (INIS)

McAskill, N.A.

1976-01-01

The emulsion polymerisation of slightly water soluble monomers such as styrene occurs initially in micelles of surfactant swollen with monomer and later in larger particles consisting of polymer swollen with monomer and stabilized with an outer layer of surfactant. There is considerable controversy on whether the reaction sites of polymerization are inside or on the surface of the particle or micelle. The relative amounts of micelle and particles present at various stages of the polymerization are also nuclear. In the present study the OH radical formed by pulse radiolysis has been used as a probe to investigate the site of solubilization of styrene in various surfactant micelles. Two products can be distinguished by UV spectrometry, a benzyl type radical formed by OH addition to the side chain of styrene and a cyclohexadienyl type radical formed by addition to the ring. Wide differences in the relative amounts of each product were observed suggesting that in some surfactants the styrene ring is buried inside the micelle whilst in other systems the styrene appears to be so solubilized at the interface leaving both the ring and the side chain open to attack by the OH radical. (author)

Radiolysis of water in the vicinity of passive surfaces

International Nuclear Information System (INIS)

Moreau, S.; Fenart, M.; Renault, J.P.

2014-01-01

Highlights: • HO° production through water radiolysis is enhanced near metal surfaces. • Hastelloy and Stainless steel surfaces can also produce HO° radicals through hydrogen peroxide activation. • There is a deficit in solvated electron production compared to hydroxyl radicals near metal surfaces. - Abstract: Porous metals were used to describe the water radiolysis in the vicinity of metal surfaces. The hydroxyl radical production under gamma irradiation was measured by benzoate scavenging in water confined in a 200 nm porous Ni base alloy or in Stainless steel. The presence of the metallic surfaces changed drastically the HO° production level and lifetime. The solvated electron production was measured via glycylglycine scavenging for Stainless steel and was found to be significantly smaller than hydroxyl production. These observations imply that interfacial radiolysis may deeply impact the corrosion behavior of the SS and Ni based alloys

Radiolysis of simple quaternary ammonium salt components of Amberlite resin

International Nuclear Information System (INIS)

Dhiman, Surajdevprakash B.; LaVerne, Jay A.

2013-01-01

The radiation chemical yields of gaseous products, H 2 and CH 4 , in the radiolysis of dry methylammonium chloride, dimethylammonium chloride, trimethylammonium chloride, tetramethylammonium chloride and benzyl trimethylammonium chloride by γ-rays and 5 MeV helium ions have been investigated. Some of these amines are the different components of the quaternary ammonium resin Amberlite, which is a strongly basic anion exchange resin based on a polystyrene divinylbenzene copolymer. Molecular hydrogen yields with γ-radiolysis range from a high of 4.43 molecules per 100 eV for trimethylammonium chloride to 0.07 and 0.05 molecules per 100 eV for tetramethylammonium chloride and benzyl trimethylammonium chloride, respectively. Yields of methane gas are generally negligible except for trimethylammonium chloride and tetramethylammonium chloride, 0.26 and 0.02 molecules per 100 eV, respectively. Isotopic labeling studies suggest that the first step in H 2 production is the breakage of the N-H bond followed by abstraction of H · atom from the methyl groups. EPR analysis shows the formation of both N and C centered radicals. A comparison is made between the radiolysis of Amberlite and its various components

Simultaneous action of external irradiation and products of air radiolysis

International Nuclear Information System (INIS)

Golikov, V.Ya.; Karklinskaya, O.N.; Mikhalev, V.P.; Vorotyntsev, A.P.; Kotov, N.N.

1977-01-01

To study the radiation damage due to the simultaneous effect of the acute ionizing radiation on the organism and the products of air radiolysis-ozone and nitrogen oxides, laboratory experiments were made. The scheme of the irradiation was the following: the acute dynamic effect (per hour) of X-rays at different doses, and nitrogen oxides and ozone with different concentrations. Male mice were exposed to irradiation (dose of 50-1000 rad, for 60 min.). Data obtained (mortality, survival, exponents of the peripheral blood) proved the radioprotective ability of the chemical agents under study. The radioprotective action was most pronounced at high concentrations. The fact proves that the mechanism of the simultaneous action of the products of air radiolysis and X-ray radiation is complex, and further efforts should be made at its investigation

Radiolysis of water confined in zeolites 4A: application to tritiated water storage

International Nuclear Information System (INIS)

Frances, Laetitia

2014-01-01

Self-radiolysis of tritiated water (HTO) adsorbed in zeolites 4A shows differences compared to free-bulk water radiolysis. We studied the roles of zeolites on that. We took special care with the influence of water loading ratio. We first exposed zeolites to external irradiations, reproducing selectively the dose or the dose rate measured in the case of tritiated water storage. This strategy enables the characterising of the samples after their irradiation since they are not contaminated by tritium. Those experiments revealed the high stability of zeolites 4A. We used a second approach which consisted in studying the precise case of self-radiolysis of tritiated water, in order to obtain radiolytic yields representative of HTO storage. The comparison between the quantities of gas released when zeolites are exposed to the three different sources that we used (electrons accelerated at 10 MeV, γ released by radioactive decay of 137 Cs and β - released by radioactive decay of tritium) revealed the strong influence of the dose rate. Moreover, whatever the irradiation source, zeolites 4A first favour hydrogen release and secondarily oxygen release too. On the contrary, zeolites favour next a recombination between those radiolytic products, with a dependence on their water loading ratio. Several processes are discussed to explain such a phenomena, not noticed during the free-bulk water radiolysis. (author) [fr

Solid state radiolysis of sulphur-containing amino acids. Cysteine, cystine and methionine

International Nuclear Information System (INIS)

Franco Cataldo; Pietro Ragni; Susana Iglesias-Groth; Arturo Manchado

2011-01-01

The sulphur-containing proteinaceous amino acids l-cysteine, l-cystine and l-methionine were irradiated in the solid state to a dose of 3.2 MGy. This dose corresponds to that delivered by radionuclide decay in a timescale of 1.05 x 10 9 years to the organic matter buried at a depth >20 m in comets and asteroids. The purity of the sulphur-containing amino acids was studied by differential scanning calorimetry (DSC) before and after the solid state radiolysis and the preservation of the chirality after the radiolysis was studied by chirooptical methods (optical rotatory dispersion, ORD) and by FT-IR spectroscopy. Although the high radiation dose of 3.2 MGy delivered, all the amino acids studied show a high radiation resistance. The best radiation resistance was offered by l-cysteine. The radiolysis of l-cysteine leads to the formation of l-cystine. The radiation resistance of l-methionine is not at the level of l-cysteine but also l-methionine is able to survive the dose of 3.2 MGy. Furthermore in all cases examined the preservation of chirality after radiolysis was clearly observed by the ORD spectroscopy although a certain level of radioracemization was measured in all cases. The radioracemization is minimal in the case of l-cysteine and is more pronounced in the case of l-methionine. In conclusion, the study shows that the sulphur-containing amino acids can survive for 1.05 x 10 9 years and, after extrapolation of the data, even to the age of the Solar System i.e. to 4.6 x 10 9 years. (author)

HANARO secondary coolant management

International Nuclear Information System (INIS)

Kim, Seon Duk.

1998-02-01

In this report, the basic theory for management of water quality, environmental factors influencing to the coolant, chemicals and its usage for quality control of coolant are mentioned, and water balance including the loss rate by evaporation (34.3 m 3 /hr), discharge rate (12.665 m 3 /hr), concentration ratio and feed rate (54.1 m 3 /hr) are calculated at 20 MW operation. Also, the analysis data of HANSU Limited for HANARO secondary coolant (feed water and circulating coolant) - turbidity, pH, conductivity, M-alkalinity, Ca-hardness, chloride ion, total iron ion, phosphoric ion and conversion rate are reviewed. It is confirmed that the feed water has good quality and the circulating coolant has been maintained within the control specification in general, but some items exceeded the control specification occasionally. Therefore it is judged that more regular discharge of coolant is needed. (author). 6 refs., 17 tabs., 18 figs

Pulse radiolysis studies of fast reactions in molecular systems. Progress report, November 1976--October 1977

International Nuclear Information System (INIS)

Dorfman, L.M.

1977-01-01

Results from research in the following two areas are given: formation, properties, and reactivity of molecular ionic species in irradiated liquid systems; and pulse radiolysis of elementary reactions in protein function

Infrared and ultraviolet spectroscopic studies of low-temperature radiolysis of ethylene - styrene copolymers

International Nuclear Information System (INIS)

Mal'tseva, A.P.; Golikov, V.P.; Leshchenko, S.S.; Karpov, V.L.

1977-01-01

Certain features of low-temperature radiolysis of statistic ethylene-styrene copolymers have been studied by infrared and ultraviolet spectroscopy. It is shown that the nature of the accumulation and decay of trans-vinylene, vinyl and vinylidene double bonds in an ethylene-styrene copolymer is essentially influenced by both the dose absorbed and copolymer composition. A suggestion is made that the ethylene-styrene copolymer is formed when structures are irradiated containing double bonds conjugated with the phenyl rings of styrene groups - which more effectively dissipate the absorbed energy than solitary phenyl rings

Photochemistry of CS2/Cl complexes-combined pulse radiolysis-laser flash photolysis studies

International Nuclear Information System (INIS)

Sumiyoshi, Takashi; Nakayama, Masayoshi; Fujiyoshi, Ryoko; Sawamura, Sadashi

2006-01-01

Complexes of chlorine atoms and carbon disulfide (CS 2 ) were produced by pulse radiolysis of CS 2 in halocarbons and photochemical reactions were studied by laser flash photolysis. Excitation of CS 2 /Cl complexes resulted in rapid and permanent photobleaching. The photobleaching of CS 2 /Cl complexes is due to intermolecular chlorine atom abstraction in CCl 4 with a quantum yield of 0.04, while that ascribed to hydrogen atom abstraction in 1,2-dichloroethane has a quantum yield of 0.21. The effects of additives are discussed based on the bond dissociation energy

Cleaning of aluminum after machining with coolants

International Nuclear Information System (INIS)

Roop, B.

1992-01-01

An x-ray photoemission spectroscopic study was undertaken to compare the cleaning of the Advanced Photon Source (APS) aluminum extrusion storage ring vacuum chambers after machining with and without water soluble coolants. While there was significant contamination left by the coolants, the cleaning process was capable of removing the residue. The variation of the surface and near surface composition of samples machined either dry or with coolants was negligible after cleaning. The use of such coolants in the machining process is therefore recommended

γ-radiolysis of dialkyl, alkyl-aryl and diaryl sulphones

International Nuclear Information System (INIS)

Bowmer, T.N.; O'Donnell, J.H.

1981-01-01

Dialkyl sulphones, RSO 2 R, have been considered as model compounds for the radiolysis of poly(olefin sulphone)s. They show preferential C-S scission and SO 2 elimination, attributable to the relatively low strengths of these bonds. Combination of the alkyl radicals, which are produced singly or in pairs according to whether one or two C-S scissions occur in one molecule, competes with hydrogen abstraction from sulphone molecules. The latter is favoured for single C-S scissions and as the size of the radical increases and hence its mobility decreases. An important degradation reaction in radiolysis is considered to be ionization to form the cation radical of the dialkyl sulphone, followed by a single C-S scission to produce the alkyl radical and the complementary alkyl sulphonyl cation, which may undergo scission of the remaining C-S bond to produce SO 2 . GC/MS studies of the volatile products from dimethyl sulphone have shown that radiolysis results in a complexity of fragmentation and combination reactions, involving scission of most bonds in the molecule. The variety of products has been confirmed using CD 3 SO 2 CD 3 . Radiation protection by aromatic substituents has been demonstrated and branched alkyls have been shown to give higher yields of alkanes and SO 2 than linear alkyls. (author)

Muon radiolysis affected by density inhomogeneity in near-critical fluids.

Science.gov (United States)

Cormier, P J; Alcorn, C; Legate, G; Ghandi, K

2014-04-01

In this article we show the significant tunability of radiation chemistry in supercritical ethane and to a lesser extent in near critical CO2. The information was obtained by studies of muonium (Mu = μ(+)e(-)), which is formed by the thermalization of positive muons in different materials. The studies of the proportions of three fractions of muon polarization, PMu, diamagnetic PD and lost fraction, PL provided the information on radiolysis processes involved in muon thermalization. Our studies include three different supercritical fluids, water, ethane and carbon dioxide. A combination of mobile electrons and other radiolysis products such as (•)C2H5 contribute to interesting behavior at densities ∼40% above the critical point in ethane. In carbon dioxide, an increase in electron mobility contributes to the lost fraction. The hydrated electron in water is responsible for the lost fraction and decreases the muonium fraction.

Radiolysis study of the oxidation of a vitamin K model compound in ethanolic solution

International Nuclear Information System (INIS)

Fackir, L.; Jore, D.; Gardes-Albert, M.; Ferradini, C.; Acher, F.; Azerad, R.

1993-01-01

It seems that the biological action of vitamin K (with its important role in carboxylating processes) may involve monoelectronic exchanges. Therefore radical mechanisms of a vitamin K model molecule KHp have been studied in ethanolic solution by mean of steady state radiolysis method. The oxidation of KHp by H 3 C-CH(OH)OO . model peroxyl radicals leads to the formation of a 'dimeric' form of vitamin K. The superoxide anions seem not to be reactive towards KHp in the chosen irradiation conditions

Glycoside bond cleavage in the radiolysis of aqueous solutions of methylglycosides and disaccharides

International Nuclear Information System (INIS)

Shadyro, O.I.; Kisel', R.M.

2007-01-01

The kinetics of formation of methylglycoside and disaccharide radiolysis products resulting from the O-glycoside bond cleavage under the action of 137 Cs γ-radiation (0-2.5 kGy radiation doses, 0.28 Gy/s dose rate) was studied, and the yields of these products were determined. It was found that oxygen inhibits these processes. The findings suggest that the fragmentation reaction of C' 2 radicals plays an important role in the formation of carbohydrate degradation products in the radiolysis of aqueous carbohydrate solutions [ru

Pulse radiolysis study of the intermediates formed in ionic liquids. Intermediate spectra in the p-terphenyl solution in the ionic liquid methyltributylammonium bis[(trifluoromethyl)sulfonyl]imide

International Nuclear Information System (INIS)

Grodkowski, J.; Kocia, R.; Mirkowski, J.

2006-01-01

Room temperature ionic liquids (Il) are non-volatile,and non-flammable and serve as good solvents for various reactions, mainly for g reen processing . To understand the effect of these solvents on the chemical reactions, the rate constants of several elementary reactions in ionic liquids have been studied by the pulse radiolysis technique. In this study, the formation of intermediates derived from p-terphenyl (Tp) in the ionic liquid methyl tributylammonium bis[(trifluoromethyl)sulfonyl] imide (R 4 NNTf 2 ) solutions have been studied by pulse radiolysis as a part of broader studies concerning CO 2 reduction. The registered spectra can be explained by CO 2 reaction with solvated and dry electrons thus eliminating one path of TP ·- formation. Some TP ·- are formed by reaction of excited TP *- states with Tea. Direct reactions involving Tp, TP ·- , CO 2 and CO 2 ·- are too slow to be observed in pulse radiolysis time scale

Gamma radiolysis of the highly selective ligands CyMe_4BTBP and CyMe_4BTPhen: Qualitative and quantitative investigation of radiolysis product

International Nuclear Information System (INIS)

Schmidt, H.; Wilden, A.; Modolo, G.; Bosbach, D.; Santiago-Schuebel, B.; Hupert, M.; Svehla, J.; Gruner, B.; Ekberg, C.

2016-01-01

The highly selective nitrogen donor ligands CyMe_4BTBP and CyMe4_BTPhen where γ-irradiated under identical experimental conditions in 1-octanol with and without contact to nitric acid solution. Subsequently, solvent extraction experiments were carried out to evaluate the stability of the extractants against γ-radiation monitoring Am(III) and Eu(III) distribution ratios. Generally, decreasing distribution ratios with increasing absorbed dose were detected for both molecules. Furthermore, qualitative mass spectrometric analyses were performed and ligand concentrations were determined by HPLC-DAD after irradiation to investigate the radiolysis mechanism. An exponential decrease with increasing absorbed dose was observed for both ligands with a faster rate for CyMe_4BTPhen. Main radiolysis products indicated the addition of one or more diluent molecules (1-octanol) to the ligand via prior production of α-hydroxy-octyl radicals from diluent radiolysis. The addition of nitric acid during the irradiation lead to a remarkable stabilization of the system, as the extraction of Am(III) and Eu(III) did not change significantly over the whole examined dose range. Quantification of the remaining ligand concentration on the other hand showed decreasing concentrations with increasing absorbed dose. The stabilization of D values is therefore explained by the formation of 1-octanol addition products which are also able to extract the studied metal ions. (authors)

Development of a new picosecond pulse radiolysis system by using a femtosecond laser synchronized with a picosecond linac. A step to femtosecond pulse radiolysis

Energy Technology Data Exchange (ETDEWEB)

Yoshida, Yoichi; Yamamoto, Tamotsu; Miki, Miyako; Seki, Shu; Okuda, Shuichi; Honda, Yoshihide; Kimura, Norio; Tagawa, Seiichi [Osaka Univ., Ibaraki (Japan). Inst. of Scientific and Industrial Research; Ushida, Kiminori

1997-03-01

A new picosecond pulse radiolysis system by using a Ti sapphire femtosecond laser synchronized with a 20 ps electron pulse from the 38 MeV L-band linac has been developed for the research of the ultra fast reactions in primary processes of radiation chemistry. The timing jitter in the synchronization of the laser pulse with the electron pulse is less than several picosecond. The technique can be used in the next femtosecond pulse radiolysis. (author)

Effects of seawater components on radiolysis of water at elevated temperature

International Nuclear Information System (INIS)

Wada, Yoichi; Tachibana, Masahiko; Ishida, Kazushige; Ota, Nobuyuki; Shigenaka, Naoto; Inagaki, Hiromitsu; Noda, Hiroshi

2014-01-01

Effects of seawater components on radiolysis of water at elevated temperature have been studied with a radiolysis model in order to evaluate influence on integrity of materials used in an ABWR. In 2011, seawater flowed into a wide part of the nuclear power plant system of the Hamaoka Nuclear Power Station Reactor No. 5 owned by Chubu Electric Power Co., Inc. after condenser tubes broke during the plant shutdown operation. The reactor water temperature was 250°C and its maximum Cl − concentration was ca. 450 ppm when seawater was mixed with reactor water. In order to clarify effects of the sea water components on radiolysis of water at elevated temperature, a radiolysis model calculation was conducted with Hitachi's radiolysis analysis code 'SIMFONY'. For the calculation, the temperature range was set from 50 to 250°C with 50°C increments and the gamma dose rate was set at 60 Gys −1 to see the effect of gamma irradiation from fuels under shutdown conditions. Concentrations of radiolytic species were calculated for 10 5 s. Dilution ratio of seawater was changed to see the effects of concentration of seawater components. Reaction rate constants of the Cl − , Br − , HCO 3 − , and SO 4 2− systems were considered. The main radiolytic species were predicted to be hydrogen and oxygen. Hydrogen peroxide of low concentration was produced in seawater-mixed water at elevated temperatures. Compared with these main products, concentrations of radiolytic products originating from chloride ion and other seawater components were found to be rather low. The dominant product among them was ClO 3 − and its concentration was found to be below 0.01ppm at 10 5 s. Then, during the plant shutdown operation, the harmful influence from radiolytic species originating from seawater components on integrity of fuel materials must be smaller than that of chloride ion which is the main ionic species in seawater. (author)

Radiolysis ob benzene, toluene and phenol aqueous solutions utilizing high energy electron beam

International Nuclear Information System (INIS)

Gonzalez Vanderhaghen, D.E.

1998-01-01

In a search for solutions to environmental pollution problems, radiolysis has proved to be an innovative technique for the removal of organic chemical pollutants in aqueous solution. Radiolysis has shown many advantages over many other techniques, as highly reactive species formed in water by ionizing radiation oxidize organic pollutants breaking down organic molecules to final simple products by oxidation to carbon dioxide and water in a complete oxidation. Our work consisted in doing some experiments in radiolysis with simulated polluted water to help us understand this technique and also develop, in a near future, a project for large scale water treatment. Our project includes the application of a Pelletron type Mexican made Electron Accelerator, which will affirm its capability and usefulness in performing investigation in this field of study. Experiments consisted in treating benzene, toluene and phenol aqueous solutions with an Electron Beam (0.48-0.55 MeV; 24 μA). Two concentrations were used for each compound: 5 and 20 ppm (mg/l) for benzene and toluene; 10 and 50 ppm for phenol. Solutions were prepared with pure, mineral free water and two different p H (5.9), in order to study the effect of concentration and p H on removal efficiency, but avoiding the interference of radical scavengers. Results obtained coincide with the ones reported by Cooper, Nickelsen and Kurucz; highly efficient removal was achieved for benzene (>99.8%), toluene (>98.0%) and phenol (>88%). There was no visible important effect of p H on radiolysis efficiency for benzene nor toluene, phenol however, showed lower removal efficiency in acidic conditions. Concentration of aqueous solutions, nevertheless, did show an important effect at low doses for phenol. Results obtained reveal the importance of this technique in water pollution control and water remedial as expressed by Cooper, Nickelsen and Kurucz, who have studied radiolysis of organic compounds and apply this technique in water

Chemical and radiolytical characterization of perfluorocarbon fluids used as coolants for LHC experiments : radiolysis effects in perfluorohexane fluids.

CERN Document Server

Ilie, Soran; Teissandier, B; CERN. Geneva. TS Department

2007-01-01

Perfluorohexane fluids, used as coolants within High Energy Physics Detectors in the Large Hadrons Collider (LHC) at CERN, were irradiated using gammas 60Co and characterized using different analytical techniques. The aim of this work was the assessment of radiation induced effects as a function of the chemical nature of these fluids and their impurity content. Were evidenced the radioinduced polymers and acidity, as well as different chemical by-products. Purification tests and measurements were carried out on different irradiated fluid samples to assess the efficiency of such purification treatments in view of their re-use in the HEP detector cooling systems.

Interaction study of water radiolysis products with Crotalus durissus terrificus miotoxin

International Nuclear Information System (INIS)

Silva, Murilo Casare da

2008-01-01

Ionizing radiation has been satisfactorily employed for venoms detoxification. In this report, the radiation was employed to verify the effects caused by the radiolysis products of water on the Crotamine, toxin purified from Crotalus durissus terrificus venom. These effects were analyzed using some substances called 'scavengers', those substances competes for specific reactive species hindering them to act on the toxins molecules. In order to study the possible structural damages caused on the toxins, circular dichroism, fluorescence, nuclear magnetic resonance, amino acids analysis and intravital microscopy were employed. Our results indicate that ionizing radiation caused structure alterations, mainly, in secondary and tertiary structure of crotamine. In the irradiated crotamine, was not possible to determine tridimensional structure. And the crotamine toxic effect was removed by ionizing radiation. (author)

The synthesis and analysis of diuloses and deoxydiuloses with special reference to the radiolysis products of fructose

International Nuclear Information System (INIS)

Den Drijver, L.

1979-12-01

The exposure of fruit to γ-irradiation is a technique that is receiving increasing attention as a practical and economic preservation method. The analysis of irradiated fruit is necessary in order to identify and quantify possible mutagenic and toxic products formed during irradiation. Water and carbohydrates are the main components of fruit, the carbohydrates consisting mainly of mono- and disaccharides. An investigation of the radiolysis products of sugars, with special reference to hexosuloses and hexosdiuloses as possible toxic and/or mutagenic agents, formed the basis of the work described in this thesis. A number of diuloses formally derived from D-fructose was synthesized for mutagenicity tests and as standards for an investigation of the radiolysis products of D-fructose. High pressure liquid chromatography was used as analytical technique. The investigation represents the first application of the technique for the analysis of radiolysis products of sugars. It was succesfully applied to a study of the diuloses formed by the radiolysis of D-fructose in the presence of oxygen. The results obtained confirmed earlier work carried out with GC-MS as analytical technique. In addition, a previously unknown radiolysis product of D-fructose was identified as D-erythrohexos-2,3-diulose

Pulse radiolysis study on several fluoroquinolones

Energy Technology Data Exchange (ETDEWEB)

Zhang Peng [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China); Graduate University of Chinese Academy of Science, Beijing 100049 (China); Yao Side [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China); Li Haixia; Song Xiyu; Liu Yancheng [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China); Graduate University of Chinese Academy of Science, Beijing 100049 (China); Wang Wenfeng, E-mail: wangwenfeng@sinap.ac.c [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China)

2011-04-15

Reactions of several fluoroquinolones (FQs), including enoxacin, norfloxacin, and ciprofloxacin, with various reactive species such as e{sub aq}{sup -}, N{sup {center_dot}}{sub 3}, and {sup {center_dot}O}H are investigated by pulse radiolysis techniques. The FQ radical anions formed in the reactions of FQs with e{sub aq}{sup -} could either be protonated or deprotonated, and the absorption of FQ radical anions was located around 370 nm. The absorption of the neutral radicals produced in the protonation, and the radical dianions produced in the deprotonation of FQ radical anions were located in the 500-750 nm region. The FQ radical cations formed in the reactions of FQs with N{sub 3}{sup {center_dot}} showed an absorption band around 360 nm. Due to the strong bleaching below 350 nm, the absorption maxima ({lambda}{sub max}) of FQ radical anions, and the {lambda}{sub max} of FQ radical cations were not confirmed. The absorption of the FQ radical anions and cations was clearly pH dependent. Under neutral conditions, the reaction rate constants of FQs with e{sub aq}{sup -} and {sup {center_dot}O}H, which are diffusion controlled, were determined.

Early stages of methanol radiolysis from data of photoelectron spectroscopy and mass spectrometry

International Nuclear Information System (INIS)

Kalyazin, E.P.; Kovalev, G.V.

1982-01-01

Comparison of data on photoelectron spectroscopy and mass spectrometry permits to conclude that 4 types of molecular ions CH 3 O + H, H + CH 2 OH, H 3 C + OH and CH 3 O + H are initial products of methanol radiolysis. They start four parallel lines of methanol transformations. Mass spectrum of methanol can be evaluated according to the structural formula of methanol molecule. Composition of radiolysis products of gaseous methanol correlate satisfactorily with its mass spectrum. Reasons for the difference in compositions of radiolysis products of liquid and gaseous methanol are discussed

Radiolysis in cement-based materials ; application to radioactive waste-forms

International Nuclear Information System (INIS)

Bouniol, P.

2014-01-01

Cement-based materials appear to be an original environment with respect to radiolysis, due to their intrinsic complexity (porous, multiphasic and evolutional medium) or their very specific physico-chemical conditions (hyper-alkaline medium with pH ≥ 13, high content in calcium) or by the fact of numerous couplings existing between different phenomenologies. At the level of a radioactive cemented wasteform, a high degree of complexity is reached, in particular if the system communicates with the atmosphere (open system allowing regulation of the pressures but also the admission of O 2 , strong reactive with regards to radiolysis). Then, the radiolysis description exceeds widely the only one aspect of the decomposition of alkaline water under irradiation and makes necessary a global phenomenological approach. In this context, some 'outlying' phenomena, highly coupled with radiation chemistry, have to be taken into account because they contribute to deeply modify the net result of the radiolysis: radioactive decay of multiple αβγ emitters with filiation, phase changes (for example H 2 aq → H 2 gas) within the pores, gas transport by convection (Darcy law) and by diffusion (Fick law), precipitation/dissolution of solid phases, effect of the ionic strength and the temperature, disturbances connected to the presence of some solutes with redox potentialities (iron, sulphur). The integration work carried out on the previous points leads to an operational model (DOREMI) allowing the estimate of H 2 amounts produced by radiolysis in different cemented radioactive waste-forms. As the final expression of the model, numerical simulations constitute a relevant tool of expertise and prospecting, contributing to accompany the thought on radiolysis in cement matrices in general and in cemented waste-forms in particular. Starting from different examples, simulations can be so used in order to test some hypotheses or illustrate the greatest influence of gas transport, dose

Reactivity of OH and O– with aqueous methyl viologen studied by pulse radiolysis

DEFF Research Database (Denmark)

Solar, Sonja; Solar, Wolfgang; Getoff, Nikola

1985-01-01

The behaviour of aqueous MV2+ towards oxidizing radicals (OH and O–) has been investigated in the pH range from 6 to 14 by means of pulse radiolysis. A semi-linear optimization method was applied for resolving the complex reaction mechanism. In the pH range from 6 to 8 the rate constant for attac...

Pulse radiolysis studies of bergenin, an isocoumarin polyphenolic derivative

International Nuclear Information System (INIS)

Singh, Umang; Srinivasan, R.; Barik, A.; Priyadarsini, K.I.

2008-01-01

Bergenin, a polyphenolic isocoumarin derivative, isolated from medicinal plant Caesalpinia digynae, has been subjected for OH and oxidizing radical reactions using pulse radiolysis technique coupled with absorption detection. OH radicals cause multiple reactions, producing transients absorbing with maxima at 440 nm and 500 nm. By comparing the spectra and decay kinetics with that produced by N 3 radicals, the species absorbing at 440 nm is assigned to phenoxyl type radical and the one absorbing at 500 nm to be a hydroxyl-radical adduct, which has been found to be reducing in nature. Bergenin also reacts with peroxyl radicals, with rate constants of 4.2 x 10 6 M -1 s -1 . (author)

Pulse radiolysis studies of bergenin, an isocoumarin polyphenolic derivative

Energy Technology Data Exchange (ETDEWEB)

Singh, Umang; Srinivasan, R; Barik, A; Priyadarsini, K I [Radiation and Photochemistry Div., Bhabha Atomic Research Centre, Mumbai (India)

2008-01-15

Bergenin, a polyphenolic isocoumarin derivative, isolated from medicinal plant Caesalpinia digynae, has been subjected for OH and oxidizing radical reactions using pulse radiolysis technique coupled with absorption detection. OH radicals cause multiple reactions, producing transients absorbing with maxima at 440 nm and 500 nm. By comparing the spectra and decay kinetics with that produced by N{sub 3} radicals, the species absorbing at 440 nm is assigned to phenoxyl type radical and the one absorbing at 500 nm to be a hydroxyl-radical adduct, which has been found to be reducing in nature. Bergenin also reacts with peroxyl radicals, with rate constants of 4.2 x 10{sup 6} M{sup -1}s{sup -1}. (author)

Study of core characteristics on fuel and coolant type. Results of F/S phase-I

International Nuclear Information System (INIS)

Ikegami, Tetsuo; Hayashi, Hideyuki; Sasaki, Makoto; Mizuno, Tomoyasu; Yamadate, Megumi; Takaki, Naoyuki; Kurosawa, Norifumi; Sakashita, Yoshiaki; Naganuma, Masayuki

2001-03-01

The phase-I of the Feasibility Study of Commercialized Fast Reactor Cycle Systems (F/S) were started from July, 1999 and terminated at the end of FY2000 in order to executed examination about technology alternatives of various commercialized fast reactor (FR) recycle concepts, in response to the JNC middle long term enterprise plan. In the phase-I of this F/S, a number of conceptual candidates have been selected from the following 5 viewpoints: a) ensuring safety, b) economic competitiveness to future LWRs, c) efficient utilization of resources, d) reduction of environmental burden, e) enhancement of nuclear non-proliferation. As for this study from the above viewpoints, core characteristics of many kinds of reactors have been investigated, analyzed and examined a core / a fuel characteristic in the combinations of fuel and coolant types and power output scales. Based on these results, R and D plans of the phase-II to be performed have been proposed, and a database to select candidate reactor concepts has been prepared. The conclusions have been obtained in the phase-I are as follows: (1) Evaluation of a fuel form in every each coolant was compared. A promising fuel form was extracted as follows: an oxide and a metal fuel for sodium coolant cores, a metal and a nitride fuel for heavy metal coolant cores, an oxide and a nitride fuel for carbon dioxide coolant cores and a nitride fuel for He gas coolant cores. (2) As the general idea that performance of a core nucleus can be compatible with re-criticality evasion in sodium coolant large-sized oxide fuel cores, a axial blanket particle elimination radial heterogeneous core is one influential candidate. (3) In case of Pb-Bi coolant nature circulation medium size core with an oxide fuel, it is difficult to simultaneously achieve higher discharged burn-up and higher breeding ratio according to the viewpoints of the phase-I. (4) Core characteristics of a carbon dioxide coolant core shows to be almost equivalent to that of

Gamma radiolysis of aqueous solution of ascorbic acid

International Nuclear Information System (INIS)

Loyola V, V.M.; Azamer B, J.A.; Laviada C, A.; Luna V, P.

1977-01-01

A preliminary study of the gamma radiolysis of a 1.13 x 10 -4 Maqueous solution of ascorbic acid is presented. It was found that dehydroascorbic acid was the principal product at doses of about 75 Krad. An increase in the dehydroascorbic acid concentration rangins from 5 to 40% was obtained, these values depend mainly on the initial ascorbic acid concentration. (author)

Density dependence of the radiolysis yields of primary species from fast neutron-irradiated supercritical water at 400 {sup o}C

Energy Technology Data Exchange (ETDEWEB)

Butarbutar, S.L. [Universite de Sherbrooke, Sherbrooke, QC (Canada); National Nuclear Energy Agency, BATAN, Tangerang Selatan, Banten (Indonesia); Meesungnoen, J. [Universite de Sherbrooke, Sherbrooke, QC (Canada); Guzonas, D.A.; Stuart, C.R. [Atomic Energy of Canada Limited, Chalk River, ON (Canada); Jay-Gerin, J-P [Universite de Sherbrooke, Sherbrooke, QC (Canada)

2014-07-01

A reliable understanding of radiolysis processes in supercritical water (SCW)-cooled reactors is crucial to developing chemistry control strategies that minimize corrosion and the transport of both corrosion products and radionuclides. Chemistry control is one of the most important factors to keep the integrity of materials from degradation processes and also to reduce out-of-core radiation fields and worker dose. However, directly measuring the chemistry in reactor cores is difficult due to the extreme conditions of high temperature and pressure and mixed neutron and γ-radiation fields that are not compatible with normal chemical instrumentation. Thus, chemical models and computer simulations are an important route of investigation for predicting the detailed radiation chemistry of the coolant in a SCW reactor and the consequences for materials. Surprisingly, there is only limited information on the fast neutron radiolysis of water at high temperatures, and no experimental data are yet available on the radiolysis yields for fast neutron irradiation of SCW. In this work, Monte Carlo simulations were used to predict the G-values for the primary species e{sup -}{sub aq}, H{sup •}, H{sub 2}, {sup •}OH, and H{sub 2}O{sub 2} formed from the radiolysis of pure, deaerated SCW (H{sub 2}O) by 2-MeV mono-energetic neutrons at 400 {sup o}C as a function of water density in the range of ~0.15-0.6 g/cm{sup 3}. The 2-MeV neutron was taken as representative of a fast neutron flux in a reactor. For light water, the moderation of these neutrons after knock-on collisions with water molecules generated mostly recoil protons of 1.264, 0.465, 0.171, and 0.063 MeV having linear energy transfer (LET) values of ~3.3, 6.5, 10.4, and 11.4 keV/μm at 0.15 g/cm{sup 3}, and ~13.3, 26, 42, and 46 keV/μm at 0.6 g/cm{sup 3}, respectively. Neglecting oxygen ion recoils and assuming that the most significant contribution to the radiolysis came from these first four recoil protons, the fast

Compartmentalized safety coolant injection system

International Nuclear Information System (INIS)

Johnson, F.T.

1983-01-01

A safety coolant injection system for nuclear reactors wherein a core reflood tank is provided to afford more reliable reflooding of the reactor core in the event of a break in one of the reactor coolant supply loops. Each reactor coolant supply loop is arranged in a separate compartment in the containment structure to contain and control the flow of spilled coolant so as to permit its use during emergency core cooling procedures. A spillway allows spilled coolant in the compartment to pass into the emergency water storage tank from where it can be pumped back to the reactor vessel. (author)

Effect of parameter variation of reactor coolant pump on loss of coolant accident consequence

International Nuclear Information System (INIS)

Dang Gaojian; Huang Daishun; Gao Yingxian; He Xiaoqiang

2015-01-01

In this paper, the analyses were carried out on Ling'ao nuclear power station phase II to study the consequence of the loss of coolant accident when the homologous characteristic curves and free volumes of the reactor coolant pump changed. Two different pumps used in the analysis were 100D (employed on Ling'ao nuclear power station phase II) and ANDRITZ. The thermal characteristics in the large break LOCA accident were analyzed using CATHRE GB and CONPATE4, and the reactor coolant system hydraulics load during blow-clown phase of LOCA accident was analyzed using ATHIS and FORCET. The calculated results show that the homologous characteristic curves have great effect on the thermal characteristics of reactor core during the reflood phase of the large break LOCA accident. The maximum cladding surface temperatures are quite different when the pump's homologous characteristic curves change. On the other hand, the pump's free volume changing results in the variation of the LOCA rarefaction wave propagation, and therefore, the reactor coolant system hydraulic load in LOCA accident would be different. (authors)

Multi-Scale Modeling of the Gamma Radiolysis of Nitrate Solutions.

Science.gov (United States)

Horne, Gregory P; Donoclift, Thomas A; Sims, Howard E; Orr, Robin M; Pimblott, Simon M

2016-11-17

A multiscale modeling approach has been developed for the extended time scale long-term radiolysis of aqueous systems. The approach uses a combination of stochastic track structure and track chemistry as well as deterministic homogeneous chemistry techniques and involves four key stages: radiation track structure simulation, the subsequent physicochemical processes, nonhomogeneous diffusion-reaction kinetic evolution, and homogeneous bulk chemistry modeling. The first three components model the physical and chemical evolution of an isolated radiation chemical track and provide radiolysis yields, within the extremely low dose isolated track paradigm, as the input parameters for a bulk deterministic chemistry model. This approach to radiation chemical modeling has been tested by comparison with the experimentally observed yield of nitrite from the gamma radiolysis of sodium nitrate solutions. This is a complex radiation chemical system which is strongly dependent on secondary reaction processes. The concentration of nitrite is not just dependent upon the evolution of radiation track chemistry and the scavenging of the hydrated electron and its precursors but also on the subsequent reactions of the products of these scavenging reactions with other water radiolysis products. Without the inclusion of intratrack chemistry, the deterministic component of the multiscale model is unable to correctly predict experimental data, highlighting the importance of intratrack radiation chemistry in the chemical evolution of the irradiated system.

Nuclear reactor coolant channels

International Nuclear Information System (INIS)

Macbeth, R.V.

1978-01-01

Reference is made to coolant channels for pressurised water and boiling water reactors and the arrangement described aims to improve heat transfer between the fuel rods and the coolant. Baffle means extending axially within the channel are provided and disposed relative to the fuel rods so as to restrict flow oscillations occurring within the coolant from being propagated transversely to the axis of the channel. (UK)

Gas phase radiolysis and vacuum ultraviolet photolysis of heterocyclic organic compounds. Progress report, February 1, 1974--February 1, 1975

International Nuclear Information System (INIS)

Scala, A.A.; Salomon, D.; Colon, I.; D'Angona, J.

1975-01-01

In the γ radiolysis of tetrahydrofuran there are pronounced density effects in the pressure range from 0 to 50 Torr with the most important ion-pair yields decreasing as the pressure increases. The relative product yields of the radiolysis is compared with that of xenon photolysis. Possible mechanisms to explain the results obtained are discussed. The ion-pair yields from the γ radiolysis of the heterocyclic amines, ethylenimine, azetidine, pyrrolidine, and piperidine, are determined, and the pressure effects are evaluated. Reactions mechanisms are discussed. The vacuum ultraviolet photolysis products of thietane and tetrahydrothiophene are studied and compared with the γ radiolysis products. Reaction mechanisms are discussed. The status of the construction of a photoionization mass spectrometer and the measurement of the ionization efficiencies and extinction coefficients of organic compounds is reported. (U.S.)

Resolved multisite OH-attack on aqueous aniline studied by pulse radiolysis

International Nuclear Information System (INIS)

Solar, S.; Solar, W.; Getoff, N.

1986-01-01

The individual formation and decay kinetics as well as the absorption characteristics of the simultaneously formed primary species by OH attack on aniline in aqueous solution (pH 8-9.6), saturated with N 2 O, have been determined by pulse radiolysis combined with a computer optimization procedure. Further the rate constant of e - sub(aq) with aniline was determined to (3.0+-0.1) x l0 7 dm 3 mol -1 cm -1 . Qualitative analysis of final products were also performed. (author)

Coolant system decontamination

International Nuclear Information System (INIS)

Anstine, L.D.; James, D.B.; Melaika, E.A.; Peterson, J.P.

1981-01-01

An improved method for decontaminating the coolant system of water cooled nuclear power reactors and for regenerating the decontamination solution is described. A small amount of one or more weak-acid organic complexing agents is added to the reactor coolant, and the pH is adjusted to form a decontamination solution which is circulated throughout the coolant system to dissolve metal oxides from the interior surfaces and complex the resulting metal ions and radionuclide ions. The coolant containing the complexed metal ions and radionuclide ions is passed through a strong-base anion exchange resin bed which has been presaturated with a solution containing the complexing agents in the same ratio and having the same pH as the decontamination solution. As the decontamination solution passes through the resin bed, metal-complexed anions are exchanged for the metal-ion-free anions on the bed, while metal-ion-free anions in the solution pass through the bed, thus removing the metal ions and regenerating the decontamination solution. (author)

First Study of Helium Gas Purification System as Primary Coolant of Co-Generation Reactor

International Nuclear Information System (INIS)

Piping Supriatna

2009-01-01

The technological progress of NPP Generation-I on 1950’s, Generation-II, Generation-III recently on going, and Generation-IV which will be implemented on next year 2025, concept of nuclear power technology implementation not only for generate electrical energy, but also for other application which called cogeneration reactor. Commonly the type of this reactor is High Temperature Reactor (HTR), which have other capabilities like Hydrogen production, desalination, Enhanced Oil Recovery (EOR), etc. The cogeneration reactor (HTR) produce thermal output higher than commonly Nuclear Power Plant, and need special Heat Exchanger with helium gas as coolant. In order to preserve heat transfer with high efficiency, constant purity of the gas must be maintained as well as possible, especially contamination from its impurities. In this report has been done study for design concept of HTR primary coolant gas purification system, including methodology by sampling He gas from Primary Coolant and purification by using Physical Helium Splitting Membrane. The examination has been designed in physical simulator by using heater as reactor core. The result of study show that the of Primary Coolant Gas Purification System is enable to be implemented on cogeneration reactor. (author)

Gamma radiolysis of the highly selective ligands CyMe{sub 4}BTBP and CyMe{sub 4}BTPhen: Qualitative and quantitative investigation of radiolysis product

Energy Technology Data Exchange (ETDEWEB)

Schmidt, H.; Wilden, A.; Modolo, G.; Bosbach, D. [Forschungszentrum Juelich GmbH, Institute of Energy and Climate Research IEK-6: Nuclear Waste Management, 52425 Juelich (Germany); Santiago-Schuebel, B.; Hupert, M. [Forschungszentrum Juelich GmbH, Central Institute for Engineering, Analytics - ZEA-3, 52425 Juelich (Germany); Svehla, J.; Gruner, B. [Institute of Inorganic Chemistry, Academy of Sciences, Hlavni 1001, 25068 Husinec-Rez (Czech Republic); Ekberg, C. [Department of Chemical and Biochemical Engineering, Chalmers University of Technology, 41296 Gothenburg (Sweden)

2016-07-01

The highly selective nitrogen donor ligands CyMe{sub 4}BTBP and CyMe4{sub B}TPhen where γ-irradiated under identical experimental conditions in 1-octanol with and without contact to nitric acid solution. Subsequently, solvent extraction experiments were carried out to evaluate the stability of the extractants against γ-radiation monitoring Am(III) and Eu(III) distribution ratios. Generally, decreasing distribution ratios with increasing absorbed dose were detected for both molecules. Furthermore, qualitative mass spectrometric analyses were performed and ligand concentrations were determined by HPLC-DAD after irradiation to investigate the radiolysis mechanism. An exponential decrease with increasing absorbed dose was observed for both ligands with a faster rate for CyMe{sub 4}BTPhen. Main radiolysis products indicated the addition of one or more diluent molecules (1-octanol) to the ligand via prior production of α-hydroxy-octyl radicals from diluent radiolysis. The addition of nitric acid during the irradiation lead to a remarkable stabilization of the system, as the extraction of Am(III) and Eu(III) did not change significantly over the whole examined dose range. Quantification of the remaining ligand concentration on the other hand showed decreasing concentrations with increasing absorbed dose. The stabilization of D values is therefore explained by the formation of 1-octanol addition products which are also able to extract the studied metal ions. (authors)

Theoretical studying the stability of steady-state regime of a channel with a coolant condensation

International Nuclear Information System (INIS)

Savikhin, O.G.

1987-01-01

Based on the boiling channel stability theory, the channel steady-state stability with the coolant condensation is studied. Condensable coolants are used in the NPP steam-separator superheaters as well as in cryogenic technique. Under certain conditions the coolant flow rate and temperature fluctuations may be excited in the parallel channel system with coolant condensation, which produce a sufficient effect on the heat exchange equipment operation reliability. To describe unsteady processes of heat and mass transfer in the channel, a homogeneous two-phase flow one dimensional model is used. The results obtained allow one to make a conclusion concerning the effect of some parameters on condensing channel steady-state regime stability: reduction of inlet and outlet unheated communication length, pressure drop increase at the outlet plate and its reduction at the inlet one lead to the increase of stability margin

The investigation of the n-#betta#-radiolysis of nitrogen tetroxide under super-critical conditions

International Nuclear Information System (INIS)

Nesterenko, V.B.; Gvozdev, A.A.; Doroshkevich, V.N.; Nichipor, G.V.; Trubnikov, V.P.

1983-01-01

The yield of the 'irreversible' products of nitrogen tetroxide radiolysis has been determined in stainless steel ampoules in the field of the reactor mixed radiation; Radiolysis has been investigated in the range of temperatures 200 to 350 deg C, pressures 7.8 to 15.7 MPa and dose rates 48 and 162 W/kg. The measured primary yield of nitrogen atoms under nitrogen dioxide radiolysis is equal to 0.28 + 0.02 at/100 eV at 250 deg C. It is shown that in the investigated range of temperatures and pressures the yield of the 'irreversible' radiolysis products can be determined using the known kinetic data on the reactions of nitrogen atoms with molecules and assuming the primary yield of nitrogen atoms from nitrogen dioxide and nitric oxide equal to 0.28 and 4.5 at/100 eV respectively. (author)

Study on the quench behavior of molten fuel material jet into coolant

International Nuclear Information System (INIS)

Abe, Yutaka; Kizu, Tetsuya; Arai, Takahiro; Nariai, Hideki; Chitose, Keiko; Koyama, Kazuya

2004-01-01

In a core disruptive accident (CDA) of a Fast Breeder Reactor, the post accident heat removal (PAHR) is crucial for the accident mitigation. The molten core material should be solidified in the sodium coolant in the reactor vessel. In the present experiment, molten material jet is injected into water to experimentally obtain fragments and the visualized information of the fragmentation. The distributed particle behavior of the molten material jet is observed with high-speed video camera. The distributions of the fragmented droplet diameter from the molten material jet are evaluated by correcting the solidified particles. The experimental results of the mean fragmented droplet diameter are compared with the existing theories. Consequently, the fragmented droplet diameter is close to the value estimated based on the Kelvin-Helmholtz instability. Once the particle diameter of the fragmented molten material could be known from a hydrodynamic model, it becomes possible to estimate the mass ratio of the molten particle to the total injected mass by combining an appropriate heat transfer model. The heat transfer model used in the present study is composed of the fragmentation model based on the Kelvin-Helmholtz instability. The mass ratio of the molten fragment to total mass of the melted mixed oxide fuel in sodium coolant estimated in the present study is very small. The result means that most of the molten mixed oxide fuel material injected into the sodium coolant can be cooled down under the solidified temperature, that is so called quenched, if the amount of the coolant is sufficient. (author)

Solid state radiolysis of non-proteinaceous amino acids in vacuum. Astrochemical implications

International Nuclear Information System (INIS)

Franco Cataldo; Giancarlo Angelini; Yaser Hafez; Susana Iglesias-Groth

2013-01-01

The analysis of the amino acids present in Murchison meteorite and in other carbonaceous chondrites has revealed the presence of 66 different amino acids. Only eight of these 66 amino acids are proteinaceous amino acids used by the present terrestrial biochemistry in protein synthesis, the other 58 amino acids are somewhat 'rare' or unusual or even 'unknown' for the current terrestrial biochemistry. For this reason in the present work a series of 'uncommon' non-proteinaceous amino acids, namely, l-2-aminobutyric acid, R(-)-2-aminobutyric acid, 2-aminoisobutyric acid (or α-aminoisobutyric acid), l-norleucine, l-norvaline, l-β-leucine, l-β-homoalanine, l-β-homoglutamic acid, S(-)-α-methylvaline and dl-3-aminoisobutyric acid were radiolyzed in vacuum at 3.2 MGy a dose equivalent to that emitted in 1.05 x 10 9 years from the radionuclide decay in the bulk of asteroids or comets. The residual amount of each amino acid under study remained after radiolysis was determined by differential scanning calorimetry in comparison to pristine samples. For optically active amino acids, the residual amount of each amino acid remained after radiolysis was also determined by optical rotatory dispersion spectroscopy and by polarimetry. With these analytical techniques it was possible to measure also the degree of radioracemization undergone by each amino acid after radiolysis. It was found that the non-proteinaceous amino acids in general do not show a higher radiation and radioracemization resistance in comparison to the common 20 proteinaceous amino acids studied previously. The unique exception is represented by ?-aminoisobutyric acid which shows an extraordinary resistance to radiolysis since 96.6 % is recovered unchanged after 3.2 MGy. Curiously α-aminoisobutyric acid is the most abundant amino acid found in carbonaceous chondrites. In Murchison meteorite α-aminoisobutyric acid represents more than 20 % of the total 66 amino acids found in this meteorite. (author)

Non-gaseous radiolysis products of procaine benzylpenicillin and Na salt 3-ortho-chloro-5-methyl-4-isoxasolyl penicillin

International Nuclear Information System (INIS)

Dziegielewski, J.; Jezowska-Trzebiatowska, B.

1974-01-01

Radiolysis products of procaine benzylpenicillin and Na salt 3-ortho-chlorophenyl-5-methyl-4-isoxasolyl penicillin were isolated and spectroscopic studies were made over the NMR, IR, UV and mass spectrometric ranges. On the basis of the results obtained, the bond breakage sites resulting from irradiation were determined and the modes of radiolysis decomposition were suggested. Irradiation of penicillins has been found to result in decomposition of the β-lactam and thiazolidine rings. Besides, decarboxylation of penicillins and bond cleavages within the amide group were observed as well as dehydrogenation and abstraction of simple hydrocarbons. The role of procaine and crystallization water in the radiolysis of penicillins was determined. (author)

Nuclear reactor coolant and cover gas system

International Nuclear Information System (INIS)

George, J.A.; Redding, A.H.; Tower, S.N.

1976-01-01

A core cooling system is disclosed for a nuclear reactor of the type utilizing a liquid coolant with a cover gas above free surfaces of the coolant. The disclosed system provides for a large inventory of reactor coolant and a balanced low pressure cover gas arrangement. A flow restricting device disposed within a reactor vessel achieves a pressure of the cover gas in the reactor vessel lower than the pressure of the reactor coolant in the vessel. The low gas pressure is maintained over all free surfaces of the coolant in the cooling system including a coolant reservoir tank. Reactor coolant stored in the reservoir tank allows for the large reactor coolant inventory provided by the invention

Coolant purification and radiochemical transformations in the presence of actadecylamine

International Nuclear Information System (INIS)

Kopylov, A.S.; Svechina, N.N.

1987-01-01

Applicability of octadecylamine (ODA) as an additive for the surfactants improve NPP steam-water circuit operation, is studied. Conditions for ODA sorption from circuit waters with different sorbents, including cationite KU-2-8 and activated carbon, are found. Material sorption capacities depending on the initial ODA concentration, temperature and filtration rate are determined. Efficiency of ODA sorption with sorbents investigated is shown to be higher than 90%. The investigation results of radiolysis of ODA aqueous emulsions in the dose interval of gamma-radiation from 1 to 10 6 rad are presented. ODA radiolysis is shown to occur analogously to radiolytic ammonia oxidation in the aqueous solution

Gamma radiolysis of alkaline aqueous solutions of neptunium and plutonium ions

International Nuclear Information System (INIS)

Pikaev, A.K.; Gogolev, A.V.; Shilov, V.P.

1998-01-01

Full text: The paper is a brief review of data obtained by the authors from the study on redox reactions of neptunium and plutonium ions upon γ radiolysis of their aerated alkaline aqueous solutions. It includes the information on radiolytic reduction of Np(V), Np(VI) and Pu(VI) ions under various experimental conditions. It was found that the values of Np(VI) and Pu(VI) reduction yields do not depend on alkali concentration. The values considerably increase in the presence of some organic compounds (EDTA and formate were investigated). The formation of the Np(V) peroxo complex was observed in the γ radiolysis of alkaline aqueous solutions of Np(VI) and Np(V) in the presence of nitrate. The mechanism of radiolytic redox reactions of the ions is discussed in some detail

Coolant clean-up and recycle systems

International Nuclear Information System (INIS)

Ito, Takao.

1979-01-01

Purpose: To increase the service life of mechanical seals in a shaft sealing device, eliminate leakages and improve the safety by providing a recycle pump for feeding coolants to a coolant clean-up device upon reactor shut-down and adapting the pump treat only low temperature and low pressure coolants. Constitution: The system is adapted to partially take out coolants from the pipeways of a recycling pump upon normal operation and feed them to a clean-up device. Upon reactor shut-down, the recycle pump is stopped and coolants are extracted by the recycle pump for shut-down into the clean-up device. Since the coolants are not fed to the clean-up device by the recycle pump during normal operation as conducted so far, high temperature and high pressure coolants are not directly fed to the recycle pump, thereby enabling to avoid mechanical problems in the pump. (Kamimura, M.)

Alternative Energy: Production of H_2 by Radiolysis of Water in the Rocky Cores of Icy Bodies

International Nuclear Information System (INIS)

Bouquet, Alexis; Waite, J. Hunter; Glein, Christopher R.; Wyrick, Danielle

2017-01-01

We applied a model of radiolysis in earthly rock–water mixtures to several known or suspected ocean worlds: Enceladus, Ceres, Europa, Titania, Oberon, Pluto, and Charon. In this model, radiation emitted by the long-lived radionuclides ("4"0K, "2"3"2Th, "2"3"5U, and "2"3"8U) contained in the ordinary chondrite-like rocks is partly absorbed by the water permeating the material of each body’s core. The physical and chemical processes that follow release molecular hydrogen (H_2), which is a molecule of astrobiological interest. We compared the calculated production of H_2 by radiolysis in each body’s core to published estimates of production by serpentinization. This study presents production calculations over 4.5 Gyr for several values of rock porosity. We found that radiolysis can produce H_2 quantities equivalent to a few percent of what is estimated from serpentinization. Higher porosity, which is unlikely at the scale of a body’s entire core but possible just under the seafloor, can increase radiolytic production by almost an order of magnitude. The products of water radiolysis also include several oxidants, allowing for production of life-sustaining sulfates. Though previously unrecognized in this capacity, radiolysis in an ocean world’s outer core could be a fundamental agent in generating the chemical energy that could support life.

Radical intermediates of low temperature radiolysis of di-tert-butylcyclohexano-18-crown-6/1-octanol extractant

International Nuclear Information System (INIS)

Zakurdaeva, O.A.; Nesterov, S.V.; Moscow State Univ.; Feldman, V.I.

2013-01-01

Intermediates of low temperature (77 K) X-rays radiolysis of 1-octanol and di-tert-butylcyclohexano-18-crown-6 solutions in 1-octanol were studied by ESR spectroscopy. Hydroxyalkyl CH 3 (CH 2 ) 6 C circle HOH and interior-type alkyl R 1 C circle HR 2 OH radicals were found to be main paramagnetic products stabilized in 1-octanol irradiated at 77 K. In addition to abovementioned radicals, macrocyclic -O-CH 2 -C circle H- and acyclic -C circle H-C(H)=O radicals produced from crown ether were identified in irradiated 1.0 M DtBuCH18C6 solution in octanol. No deviation in radiation-chemical yield of the stabilized acyclic radicals from the value expected in accord with 'additive' rule was observed in the latter case. It was supposed that macrocycle cleavage in DtBuCH18C6 occurred at early stages of radiolysis rather than in secondary radical reactions between products of 1-octanol radiolysis and crown ether. Meanwhile, alkyl radicals formed from 1-octanol can react with crown ether, resulting in formation of macrocyclic products of radiolysis. (orig.)

Radical intermediates of low temperature radiolysis of di-tert-butylcyclohexano-18-crown-6/1-octanol extractant

Energy Technology Data Exchange (ETDEWEB)

Zakurdaeva, O.A.; Nesterov, S.V. [Russian Academy of Sciences, Moscow (Russian Federation). Enikolopov Institute of Synthetic Polymer Materials; Moscow State Univ. (Russian Federation). Dept. of Chemistry; Feldman, V.I. [Moscow State Univ. (Russian Federation). Dept. of Chemistry

2013-03-01

Intermediates of low temperature (77 K) X-rays radiolysis of 1-octanol and di-tert-butylcyclohexano-18-crown-6 solutions in 1-octanol were studied by ESR spectroscopy. Hydroxyalkyl CH{sub 3}(CH{sub 2}){sub 6}C {sup circle} HOH and interior-type alkyl R{sub 1}C {sup circle} HR{sub 2}OH radicals were found to be main paramagnetic products stabilized in 1-octanol irradiated at 77 K. In addition to abovementioned radicals, macrocyclic -O-CH{sub 2}-C {sup circle} H- and acyclic -C {sup circle} H-C(H)=O radicals produced from crown ether were identified in irradiated 1.0 M DtBuCH18C6 solution in octanol. No deviation in radiation-chemical yield of the stabilized acyclic radicals from the value expected in accord with 'additive' rule was observed in the latter case. It was supposed that macrocycle cleavage in DtBuCH18C6 occurred at early stages of radiolysis rather than in secondary radical reactions between products of 1-octanol radiolysis and crown ether. Meanwhile, alkyl radicals formed from 1-octanol can react with crown ether, resulting in formation of macrocyclic products of radiolysis. (orig.)

Laser Flash Photolysis and Pulse Radiolysis of Iodate and Periodate in Aqueous Solution

DEFF Research Database (Denmark)

Kläning, U K; Sehested, Knud; Wolff, Thomas

1981-01-01

photolysis study of IeVI and I0VI suggests that the predominant IeVI and I0VI species formed are IO42– and IO3 at 3 12. Redox reactions of the iodine(VI) species are fast compared with interconversion among the various iodine(VI) species......Species containing iodine in oxidation state six are formed by photolysis and radiolysis of aqueous iodate and periodate solutions in the following reactions: IO3–+ O–→ IO42–; IO3–+ OH → IO3; IVII+ eaq–→ IeVI and IVII [graphic omitted] I0VI+ O–(or OH). The present pulse radiolysis and laser flash...

Triboengineering problems of lead coolant in innovative fast reactors

International Nuclear Information System (INIS)

Beznosov, A.V.; Novozhilova, O.O.; Shumilkov, A.I.; Lvov, A.V.; Bokova, T.A.; Makhov, K.A.

2013-01-01

Graphical abstract: Models of experimental sites for research of processes tribology in heavy liquid metal coolant. -- Highlights: • The contact a pair of heavy liquid metal coolant for reactors on fast neutrons. • The hydrostatic bearings main circulation pumps. • Oxide coating and degree of wear of friction surfaces in heavy liquid metal coolant. -- Abstract: So far, there are plenty of works dedicated to studying the phenomenon of friction. However, there are none dedicated to functioning of contact pairs in heavy liquid-metal coolants for fast neutron, reactor installations (Kogaev and Drozdov, 1991; Modern Tribology, 2008; Drozdov et al., 1986). At the Nizhny Novgorod State Technical University, such research is conducted in respect to friction, bearings of main circulating pumps, interaction of sheaths of neutron absorber rods with their covers, of the reactor control and safety system, refueling systems, and interaction of coolant flows with, channel borders. As a result of experimental studies, the characteristic of friction pairs in the heavy, liquid metal coolant shows the presence dependences of oxide film on structural materials of the wear. The inapplicability of existing calculation methods for assessing the performance of the bearing nodes, in the heavy liquid metal coolant is shown

Fenton-enhanced {gamma}-radiolysis of cyanuric acid

Energy Technology Data Exchange (ETDEWEB)

Varghese, Rani [School of Chemical Sciences, Mahatma Gandhi University, Kottayam 686560, Kerala (India); Aravind, Usha K. [School of Chemical Sciences, Mahatma Gandhi University, Kottayam 686560, Kerala (India); Aravindakumar, Charuvila T. [School of Chemical Sciences, Mahatma Gandhi University, Kottayam 686560, Kerala (India)]. E-mail: CT-Aravindakumar@rocketmail.com

2007-04-02

Degradation of cyanuric acid (OOOT), a stable end product of oxidative decomposition of atrazine, is investigated in a combined field of gamma radiolysis and fenton reaction. The reaction of hydroxyl radical ({center_dot}OH) at pH 6 was carried out by irradiating N{sub 2}O saturated aqueous solutions containing OOOT (1 x 10{sup -3} mol dm{sup -3}), and this resulted only a marginal degradation (20%). However, when the same reaction was carried out in the presence of varying concentrations of ferrous sulfate ((5-10) x 10{sup -5} mol dm{sup -3}), the decay of OOOT has been enhanced to more than 80%. This decay followed a first order kinetics. Nearly similar effects were observed with another triazine derivative, 2,4-dioxohexahydro-1,3,5-triazine (DHT). Two major reaction mechanisms are proposed for the enhanced decay of OOOT. The formation of unstable hydroxyl radical adducts from the reaction of {center_dot}OH which is the result of gamma radiolysis and the Fenton reaction (resulting from the reaction of the added Fe(II) and of the H{sub 2}O{sub 2} from the radiolysis of water), is proposed as the first mechanism. The second mechanism, which is likely the major contributor to degradation, is proposed as the reaction of a nucleophilic adduct, Fe(II)OOH, which could directly react with the electron deficient triazine ring. It is highlighted that such degradation reactions must be explored for the complete degradation of the byproducts of the oxidative decomposition of atrazine.

Radiolysis study of actinide complexing agent by irradiation with helium ion beam

International Nuclear Information System (INIS)

Sugo, Yumi; Taguchi, Mitsumasa; Sasaki, Yuji; Hirota, Koichi; Kimura, Takaumi

2009-01-01

α-Radiolysis of N,N,N',N'-tetraoctyldiglycolamide (TODGA) in n-dodecane was investigated by the irradiation with helium ion beam provided by a tandem accelerator. The radiation chemical yield for the degradation of TODGA by helium ion beam irradiation was less than that by γ-rays irradiation. It is considered that the radical cations of n-dodecane, which contribute to the charge transfer reaction with the TODGA molecules, decrease by recombination in track by high LET radiations such as α-particles.

The effect of coolant quantity on local fuel–coolant interactions in a molten pool

International Nuclear Information System (INIS)

Cheng, Songbai; Matsuba, Ken-ichi; Isozaki, Mikio; Kamiyama, Kenji; Suzuki, Tohru; Tobita, Yoshiharu

2015-01-01

Highlights: • We investigate local fuel–coolant interactions in a molten pool. • As water volume increases, limited pressurization and mechanical energy observed. • Only a part of water is evaporated and responsible for the pressurization. - Abstract: Studies on local fuel–coolant interactions (FCI) in a molten pool are important for severe accident analyses of sodium-cooled fast reactors (SFRs). Motivated by providing some evidence for understanding this interaction, in this study several experimental tests, with comparatively larger difference in coolant volumes, were conducted by delivering a given quantity of water into a simulated molten fuel pool (formed with a low-melting-point alloy). Interaction characteristics including the pressure-buildup as well as mechanical energy release and its conversion efficiency are evaluated and compared. It is found that as water quantity increases, a limited pressure-buildup and the resultant mechanical energy release are observable. The performed analyses also suggest that only a part of water is probably vaporized during local FCIs and responsible for the pressurization and mechanical energy release, especially for those cases with much larger water volumes

Coolant leakage detecting device

International Nuclear Information System (INIS)

Yamauchi, Kiyoshi; Kawai, Katsunori; Ishihara, Yoshinao.

1995-01-01

The device of the present invention judges an amount of leakage of primary coolants of a PWR power plant at high speed. Namely, a mass of coolants contained in a pressurizer, a volume controlling tank and loop regions is obtained based on a preset relational formula and signals of each of process amount, summed up to determine the total mass of coolants for every period of time. The amount of leakage for every period of time is calculated by a formula of Karman's filter based on the total mass of the primary coolants for every predetermined period of time, and displays it on CRT. The Karman's filter is formed on every formula for several kinds of states formed based on the preset amount of the leakage, to calculate forecasting values for every mass of coolants. An adaptable probability for every preset leakage amount is determined based on the difference between the forecast value and the observed value and the scattering thereof. The adaptable probability is compared with a predetermined threshold value, which is displayed on the CRT. This device enables earlier detection of leakage and identification of minute leakage amount as compared with the prior device. (I.S.)

Magnetic resonance methods used to study the mobility of lithium ions and the formation of gamma radiolysis products in lithium silicates

International Nuclear Information System (INIS)

Pronin, I.S.; Nikiforov, A.S.; Vashman, A.A.

1986-01-01

The authors present the results of research on the mobility of lithium ions and the formation of radiation induced paramagnetic centers in the gamma radiolysis of lithium ortho- and metasilicates; nuclear magnetic resonance of Li-7 and electroparamagnetic resonance were used in the studies

Coolant inlet device for nuclear reactors

International Nuclear Information System (INIS)

Ando, Hiroshi; Abe, Yasuhiro; Iwabuchi, Toshihiko; Yamamoto, Kenji.

1969-01-01

Herein disclosed is a coolant inlet device for liquid-metal cooled reactors which employs a coolant distributor serving also as a supporting means for the reactor core. The distributor is mounted within the reactor vessel so as to slide horizontally on supporting lugs, and is further slidably connected via a junction pipe to a coolant inlet conduit protruding through the floor of the vessel. The distributor is adapted to uniformly disperse the highly pressured coolant over the reactor core so as to reduce the stresses sustained by the reactor vessel as well as the supporting lugs. Moreover, the slidable nature of the distributor allows thermal shock and excessive coolant pressures to be prevented or alleviated, factors which posed major difficulties in conventional coolant inlet devices. (Owens, K. J.)

Radiolysis of the polyethylene/water system: Studies on the role of hydroxyl radical

Energy Technology Data Exchange (ETDEWEB)

Billamboz, Nicolas [Laboratoire de Chimie Physique et Rayonnement Alain Chambaudet, UMR CEA E4, Universite de Franche-Comte, 16 route de Gray, 25030 Besancon Cedex (France); Grivet, Manuel, E-mail: manuel.grivet@univ-fcomte.f [Laboratoire de Chimie Physique et Rayonnement Alain Chambaudet, UMR CEA E4, Universite de Franche-Comte, 16 route de Gray, 25030 Besancon Cedex (France); Foley, Sarah [Laboratoire de Chimie Physique et Rayonnement Alain Chambaudet, UMR CEA E4, Universite de Franche-Comte, 16 route de Gray, 25030 Besancon Cedex (France); Baldacchino, Gerard [CEA, IRAMIS, SIS2M, Laboratoire de Radiolyse, Bat. 546, F-91191 Gif-sur-Yvette (France); CNRS, Laboratoire Claude Frejacques, F-91191 Gif-sur-Yvette (France); Hubinois, Jean-Charles [CEA, DAM, Valduc, F-21120 Is-sur-Tille (France)

2010-01-15

The role of hydroxyl radical on polyethylene degradation under aqueous conditions has been studied. The reactivity of HO{sup .} towards PE is highlighted by pulse radiolysis experiments on a PE powder suspension in water using the thiocyanate competition technique. Infrared analysis of PE films irradiated in the presence of water is performed. Solutions have been either degassed with Ar, in order to remove O{sub 2} which would react with the PE, or N{sub 2}O which enhances the production of HO{sup .} radicals. Oxygenated groups and double bond groups created at the surface of PE are characterized using IR analysis, and the results for both saturated solution systems are compared.

Design and fabrication of magnetic coolant filter

Science.gov (United States)

Prashanth, B. N.

2017-07-01

Now a day's use of coolants in industry has become dominant because of high production demands. Coolants not only help in speeding up the production but also provide many advantages in the metal working operation. As the consumption of coolants is very high a system is badly in need, so as to recirculate the used coolant. Also the amount of hazardous waste generated by industrial plants has become an increasingly costly problem for the manufactures and an additional stress on the environment. Since the purchase and disposal of the spent cutting fluids is becoming increasingly expensive, fluid recycling is a viable option for minimizing the cost. Separation of metallic chips from the coolants by using magnetic coolant separation has proven a good management and maintenance of the cutting fluid. By removing the metallic chips, the coolant life is greatly extended, increases the machining quality and reduces downtime. Above being the case, a magnetic coolant filter is developed which utilizes high energy permanent magnets to develop a dense magnetic field along a narrow flow path into which the contaminated coolant is directed. The ferromagnetic particles captured and aligned by the dense magnetic field, from the efficient filter medium. This enables the unit to remove ferromagnetic particles from the coolant. Magnetic coolant filters use the principle of magnetic separation to purify the used coolant. The developed magnetic coolant separation has the capability of purifying 40 litres per minute of coolant with the size of the contaminants ranging from 1 µm to 30 µm. The filter will be helpful in saving the production cost as the cost associated with the proposed design is well justified by the cost savings in production. The magnetic field produced by permanent magnets will be throughout the area underneath the reservoir. This produces magnetic field 30mm above the coolant reservoir. Very fine particles are arrested without slip. The magnetic material used will not

Pulse radiolysis of anthraquinone dye aqueous solution

International Nuclear Information System (INIS)

Perkowski, J.; Gebicki, J.L.; Lubis, R.; Mayer, J.

1988-01-01

Pulse radiolysis of argon flushed aqueous solutions of 10 -5 -10 -4 mol dm -3 anthraquinone dye (C.I. Acid Blue 62) gives rise to the transients originated from the reactions of e - aq , OH and H. The rate constants of these reactions are determined. (author)

Radiolysis of DNA-protein complexes

Energy Technology Data Exchange (ETDEWEB)

Begusova, Marie [Department of Radiation Dosimetry, Nuclear Physics Institute, Na Truhlarce 39/64, CZ-18086, Prague 8 (Czech Republic)]. E-mail: begusova@ujf.cas.cz; Gillard, Nathalie [Centre de Biophysique Moleculaire, CNRS, rue Charles-Sadron, F-45071 Orleans Cedex 2 (France); Sy, Denise [Centre de Biophysique Moleculaire, CNRS, rue Charles-Sadron, F-45071 Orleans Cedex 2 (France); Castaing, Bertrand [Centre de Biophysique Moleculaire, CNRS, rue Charles-Sadron, F-45071 Orleans Cedex 2 (France); Charlier, Michel [Centre de Biophysique Moleculaire, CNRS, rue Charles-Sadron, F-45071 Orleans Cedex 2 (France); Spotheim-Maurizot, Melanie [Centre de Biophysique Moleculaire, CNRS, rue Charles-Sadron, F-45071 Orleans Cedex 2 (France)

2005-02-01

We discuss here modifications of DNA and protein radiolysis due to the interaction of these two partners in specific complexes. Experimental patterns of frank strand breaks (FSB) and alkali revealed breaks (ARB) obtained for DNA lac operator bound to the lac repressor and for a DNA containing an abasic site analog bound to the formamidopyrimidine-DNA glycosylase are reported. Experimental data are compared to predicted damage distribution obtained using the theoretical model RADACK.

Radiolysis of DNA-protein complexes

International Nuclear Information System (INIS)

Begusova, Marie; Gillard, Nathalie; Sy, Denise; Castaing, Bertrand; Charlier, Michel; Spotheim-Maurizot, Melanie

2005-01-01

We discuss here modifications of DNA and protein radiolysis due to the interaction of these two partners in specific complexes. Experimental patterns of frank strand breaks (FSB) and alkali revealed breaks (ARB) obtained for DNA lac operator bound to the lac repressor and for a DNA containing an abasic site analog bound to the formamidopyrimidine-DNA glycosylase are reported. Experimental data are compared to predicted damage distribution obtained using the theoretical model RADACK

Effects of energy, distance and orientation on electron transfer rates studied by pulse radiolysis in organic media

International Nuclear Information System (INIS)

Miller, J.R.

1987-01-01

In the past few years the methods of radiation chemistry in organic media have made an enormous change in how we view electron transfer processes, as these media have proved the most useful for studying long distance electron transfer between molecules. This paper briefly summarizes a few of the aspects of this area and discusses some of the attributes and limitations of radiation tehniques, particularly pulse radiolysis, in organic solvents. 14 refs., 2 figs

A review of the radiolysis of methane

International Nuclear Information System (INIS)

Norfolk, D.J.

1975-08-01

The review had three objectives: to determine the yields of the primary products and to describe the sequence of reactions in which they take part; to ascertain the effect on these reactions of changes in the physical state of the methane and the quantum energy of the radiation, and of the presence of chemically inert sensitisers; and to identify the situation most similar to the adsorbed phase radiolysis of methane on alumina, and so to predict the likely radiolytic reactions in this system. The main primary product yields in methane gas under γ-irradiation are estimated to be G(CH 4 +) approximately 1.75, G(CH 3 +) approximately 1.46, G(CH 3 ) approximately 1.4 and G(CH 2 ) approximately 1.0. The situation most similar to adsorbed phase radiolysis is inert gas sensitised photolysis at energies below 12.6eV. In this system the major primary process is homolytic dissociation of methane to CH 3 +H. (author)

The effect of ultralow temperature on olefin cation formation by ionic fragmentation in the radiolysis of 2,3-dimethylbutane

International Nuclear Information System (INIS)

Miyazaki, Tetsuo

1991-01-01

The formation of olefin cations in the radiolysis of 2,3-dimethylbutane (DMB) was studied by ESR at 4.2 and 77 K. When a DMB-SF 6 mixture is γ-irradiated at 77 K, tetramethylethylene (TME) cations are formed remarkably. The formation of the TME cations, however, is suppressed at 4.2 K. When the DMB-SF 6 mixture is γ-irradiated at 4.2 K and then warmed to 77 K, TME cations are formed by thermal annealing. The TME cations are not formed by a charge transfer to olefinic impurities or olefinic products in radiolysis, but by H 2 elimination from parent DMB cations in the ground state. The remarkable formation of olefin cations at 77 K corresponds to the large yields of unsaturated dimers in the radiolysis of DMB at 77 K. The suppression of olefin cation formation at 4.2 K corresponds to the low yields of unsaturated dimers in the radiolysis of DMB at 4.2 K. (author)

Alternative Energy: Production of H{sub 2} by Radiolysis of Water in the Rocky Cores of Icy Bodies

Energy Technology Data Exchange (ETDEWEB)

Bouquet, Alexis; Waite, J. Hunter [Department of Physics and Astronomy, University of Texas at San Antonio, San Antonio, TX (United States); Glein, Christopher R.; Wyrick, Danielle [Southwest Research Institute, Space Science and Engineering Division, San Antonio, TX (United States)

2017-05-01

We applied a model of radiolysis in earthly rock–water mixtures to several known or suspected ocean worlds: Enceladus, Ceres, Europa, Titania, Oberon, Pluto, and Charon. In this model, radiation emitted by the long-lived radionuclides ({sup 40}K, {sup 232}Th, {sup 235}U, and {sup 238}U) contained in the ordinary chondrite-like rocks is partly absorbed by the water permeating the material of each body’s core. The physical and chemical processes that follow release molecular hydrogen (H{sub 2}), which is a molecule of astrobiological interest. We compared the calculated production of H{sub 2} by radiolysis in each body’s core to published estimates of production by serpentinization. This study presents production calculations over 4.5 Gyr for several values of rock porosity. We found that radiolysis can produce H{sub 2} quantities equivalent to a few percent of what is estimated from serpentinization. Higher porosity, which is unlikely at the scale of a body’s entire core but possible just under the seafloor, can increase radiolytic production by almost an order of magnitude. The products of water radiolysis also include several oxidants, allowing for production of life-sustaining sulfates. Though previously unrecognized in this capacity, radiolysis in an ocean world’s outer core could be a fundamental agent in generating the chemical energy that could support life.

The sodium coolant

International Nuclear Information System (INIS)

Rodriguez, G.

2004-01-01

The sodium is the best appropriate coolant for the fast neutrons reactors technology. Thus the fast neutrons reactors development is intimately bound to the sodium technology. This document presents the sodium as a coolant point of view: atomic structure and characteristics, sodium impacts on the fast neutron reactors technology, chemical properties of the sodium and the consequences, quality control in a nuclear reactor, sodium treatment. (A.L.B.)

Femtosecond pulse radiolysis based on photocathode electron accelerator

International Nuclear Information System (INIS)

Yoshida, Y.; Yang, Jinfeng; Kondoh, T.; Kozawa, T.; Tagawa, S.

2006-01-01

Pulse radiolysis is a powerful tool for studying chemical kinetics and primary processes or reactions of radiation chemistry. In the pulse radiolysis, a short electron beam, which is almost produced by radio-frequency (RF) electron linear accelerator with energy from a few MeV to a few tens MeV, is used as an irradiative source. The electron-induced reactions or phenomena in matter are analyzed by a short-pulse analyzing light (e.g. synchronized lasers) with the time-resolved stroboscopic technique. The time resolution of pulse radiolysis is not only dependent on the electron bunch length, the analyzing light pulse width, the time jitter between the electron bunch and the analyzing light, but also determined by degradation due to the velocity difference between light and the electron in the sample because of the refractive index. In order to improve the time resolution into femtosecond time region, we have develop a new pulse radiolysis based on a concept of 'Equivalent Velocity Spectroscopy (EVS)' to avoid the degradation of the time resolution caused by the velocity difference between the light and the electron beam in sample. In EVS as shown in Fig.1, a femtosecond electron beam produced by a photocathode electron linear accelerator was used, and a synchronized femtosecond laser was used as the analyzing light source. The electron beam and the laser light were injected into sample with an angle (θ), which is determined by the refractive index (n) of the sample. The electron bunch was also rotated with a same angle to make an overlap of the electron bunch with the laser pulse. The degradation of the time resolution caused by the velocity difference between the light and the electron beam can be calculated as g(L)=L[n/c-1/(vcos θ)], where L is the optical path length and v is the velocity of the electron in sample (we can assume v=c for a few tens MeV electron beam).We can thus obtained g(L)=0 by adjusting the incident angle to cos θ=1/n. However, the rotation

The premixing and propagation phases of fuel-coolant interactions: a review of recent experimental studies and code developments

Energy Technology Data Exchange (ETDEWEB)

Antariksawan, A.R. [Reactor Safety Technology Research Center of BATAN (Indonesia); Moriyama, Kiyofumi; Park, Hyun-sun; Maruyama, Yu; Yang, Yanhua; Sugimoto, Jun

1998-09-01

A vapor explosion (or an energetic fuel-coolant interactions, FCIs) is a process in which hot liquid (fuel) transfers its internal energy to colder, more volatile liquid (coolant); thus the coolant vaporizes at high pressure and expands and does works on its surroundings. Traditionally, the energetic fuel-coolant interactions could be distinguished in subsequent stages: premixing (or coarse mixing), triggering, propagation and expansion. Realizing that better and realistic prediction of fuel-coolant interaction consequences will be available understanding the phenomenology in the premixing and propagation stages, many experimental and analytical studies have been performed during more than two decades. A lot of important achievements are obtained during the time. However, some fundamental aspects are still not clear enough; thus the works are directed to that direction. In conjunction, the model/code development is pursuit. This is aimed to provide a scaling tool to bridge the experimental results to the real geometries, e.g. reactor pressure vessel, reactor containment. The present review intends to collect the available information on the recent works performed to study the premixing and propagation phases. (author). 97 refs.

The premixing and propagation phases of fuel-coolant interactions: a review of recent experimental studies and code developments

International Nuclear Information System (INIS)

Antariksawan, A.R.; Moriyama, Kiyofumi; Park, Hyun-sun; Maruyama, Yu; Yang, Yanhua; Sugimoto, Jun

1998-09-01

A vapor explosion (or an energetic fuel-coolant interactions, FCIs) is a process in which hot liquid (fuel) transfers its internal energy to colder, more volatile liquid (coolant); thus the coolant vaporizes at high pressure and expands and does works on its surroundings. Traditionally, the energetic fuel-coolant interactions could be distinguished in subsequent stages: premixing (or coarse mixing), triggering, propagation and expansion. Realizing that better and realistic prediction of fuel-coolant interaction consequences will be available understanding the phenomenology in the premixing and propagation stages, many experimental and analytical studies have been performed during more than two decades. A lot of important achievements are obtained during the time. However, some fundamental aspects are still not clear enough; thus the works are directed to that direction. In conjunction, the model/code development is pursuit. This is aimed to provide a scaling tool to bridge the experimental results to the real geometries, e.g. reactor pressure vessel, reactor containment. The present review intends to collect the available information on the recent works performed to study the premixing and propagation phases. (author). 97 refs

Kinetics of the reaction F+NO+M->FNO+M studied by pulse radiolysis combined with time-resolved IR and UV spectroscopy

DEFF Research Database (Denmark)

Pagsberg, Palle Bjørn; Sillesen, A.; Jodkowski, J.T.

1996-01-01

The title reaction was initiated by pulse radiolysis of SF6/NO gas mixtures, and the formation of FNO was studied by time-resolved IR and UV spectroscopy. At SF6 pressures of 10-320 mbar at 298 K, the formation of FNO was studied by infrared diode laser spectroscopy at 1857.324 cm(-1). Comparative...

Summary of TRUEX Radiolysis Testing Using the INL Radiolysis Test Loop

Energy Technology Data Exchange (ETDEWEB)

Dean R. Peterman; Lonnie G. Olson; Rocklan G. McDowell; Gracy Elias; Jack D. Law

2012-03-01

The INL radiolysis and hydrolysis test loop has been used to evaluate the effects of hydrolytic and radiolytic degradation upon the efficacy of the TRUEX flowsheet for the recovery of trivalent actinides and lanthanides from acidic solution. Repeated irradiation and subsequent re-conditioning cycles did result in a significant decrease in the concentration of the TBP and CMPO extractants in the TRUEX solvent and a corresponding decrease in americium and europium extraction distributions. However, the build-up of solvent degradation products upon {gamma}-irradiation, had little impact upon the efficiency of the stripping section of the TRUEX flowsheet. Operation of the TRUEX flowsheet would require careful monitoring to ensure extraction distributions are maintained at acceptable levels.

Studies of loss-of-coolant and loss-of-regulation accidents

International Nuclear Information System (INIS)

Rogers, J.T.

1979-10-01

Studies of a CANDU reactor during loss of coolant with delayed emergency core cooling showed that the moderator is an effective heat sink, and that in reactors with moderator dump the calandria sprays provide effective cooling. Fuel channel melting would not occur, and a coolable geometry will be maintained. Studies on film cooling and film stability on calandria tubes and on the analysis of flow reversal in vertical feeder tubes are also reported

Corrosive gas generation potential from chloride salt radiolysis in plutonium environments

International Nuclear Information System (INIS)

Tandon, L.; Allen, T.H.; Mason, R.E.; Penneman, R.A.

1999-01-01

The specific goal of this project was to evaluate the magnitude and practical significance of radiation effects involving mixtures of chloride salts and plutonium dioxide (PuO 2 ) sealed in stainless steel containers and stored for up to 50 yr, after stabilization at 950 C and packaging according to US Department of Energy (DOE) standards. The potential for generating chemically aggressive molecular chlorine (and hydrogen chloride by interaction with adsorbed water or hydrogen gas) by radiolysis of chloride ions was studied. To evaluate the risks, an annotated bibliography on chloride salt radiolysis was created with emphasis on effects of plutonium alpha radiation. The authors present data from the material identification and surveillance (MIS) project obtained from examination and analysis of representative PuO 2 items from various DOE sites, including the headspace gas analysis data of sealed mixtures of PuO 2 and chloride salts following long-term storage

Coolant monitoring systems for PWR reactors

International Nuclear Information System (INIS)

Luzhnov, A.M.; Morozov, V.V.; Tsypin, S.G.

1987-01-01

The ways of improving information capacity of existing monitoring systems and the necessity of designing new ones for coolant monitoring are reviewed. A wide research program on development of coolant monitoring systems in PWR reactors is analyzed. The possible applications of in-core and out-of-core detectors for coolant monitoring are demonstrated

Design Features of the SMART Water Chemistry

International Nuclear Information System (INIS)

Byung Seon Choi; Seong Hoon Kim; Juhyeon Yoon; Doo Jeong Lee; Yoon Yeong Bae; Sung Kyun Zee

2004-01-01

The design features for the primary water chemistry for the SMART are introduced from the viewpoint of the system characteristics and the chemical design concept. The most essential differences in water chemistry between the commercially operating PWRs and SMART are characterized by the presence of boron in the water and the operating mode of the purification system. SMART is a soluble boron free reactor, and the ammonia is used as a pH reagent. The material for SMART steam generator is also different from the standard material of the commercially operating PWRs: titanium alloy for the steam generator tubes. In SMART hydrogen gas which suppresses a generation of oxidizing species by the radiolysis processes in the reactors is not added to the primary coolant, but is normally generated from the radiolysis of the ammonia as the coolant passes through the core. Ammonia is added once per shift because SMART reactor has no letdown and charging system during power operation. Because of these competing processes, the concentrations of hydrogen, nitrogen and ammonia in the primary coolant are in equilibrium, which depend on the decomposition and/or combination rate of the ammonia. The level of permissible oxygen concentration in the primary coolant can be ensured by both suppression of the water radiolysis through maintaining a high enough hydrogen concentration in the primary coolant and by a restriction of the oxygen ingress into the primary coolant with the makeup water. The ammonia chemistry in SMART reactor eliminates the need for hydrogen injection for the control of the dissolved oxygen in the primary coolant because of spontaneous generation of hydrogen and nitrogen produced by the reaction of the ammonia decomposition. (authors)

Organic coolant in Winnipeg riverbed sediments

International Nuclear Information System (INIS)

Guthrie, J.E.; Acres, O.E.

1979-03-01

Between January and May 1977 a prolonged leak of organic coolant occurred from the Whiteshell Nuclear Research Establishment's nuclear reactor, and a minimum of 1450 kg of coolant entered the Winnipeg River and was deposited on the riverbed. The level of radioactivity associated with this coolant was low, contributing less than 0.2 μGy (0.02 mrad) a year to the natural background gamma radiation field from the riverbed. The concentration of coolant in the water samples never exceeded 0.02 mg/L, the lower limit of detection. The mortality of crayfish, held in cages where the riverbed was covered with the largest deposits of coolant, was not significantly different from that in the control cages upstream of the outfall. No evidence of fish kill was found. (author)

Reactivity of OH radicals with chlorobenzoic acids-A pulse radiolysis and steady-state radiolysis study

Energy Technology Data Exchange (ETDEWEB)

Zona, Robert [University of Vienna, Department of Nutritional Sciences, Section Radiation Biology, UZAII, Althanstrasse 14, A-1090 Vienna (Austria); Solar, Sonja, E-mail: sonja.solar@univie.ac.a [University of Vienna, Department of Nutritional Sciences, Section Radiation Biology, UZAII, Althanstrasse 14, A-1090 Vienna (Austria); Getoff, Nikola [University of Vienna, Department of Nutritional Sciences, Section Radiation Biology, UZAII, Althanstrasse 14, A-1090 Vienna (Austria); Sehested, Knud; Holcman, Jerzy [RISO National Laboratory Environmental Science and Technology Department, DK-4000, Roskilde (Denmark)

2010-05-15

The reactions of OH radicals with 2-, 3-, 4-chlorobenzoic acids (ClBzA) and chlorobenzene (ClBz), k({sup c}entre dotOH+substrates)=(4.5-6.2)x10{sup 9} dm{sup 3} mol{sup -1} s{sup -1}, have been studied by pulse radiolysis in N{sub 2}O saturated solutions. The absorption maxima of the OH-adducts were in the range of 320-340 nm. Their decay was according to a second-order reaction, 2k=(1-9)x10{sup 8} dm{sup 3} mol{sup -1} s{sup -1}. In the presence of N{sub 2}O/O{sub 2} the formation of peroxyl radicals was detectable for 2-, 4-ClBzA and ClBz, k(OH-adduct+O{sub 2})=(2-4)x10{sup 7} dm{sup 3} mol{sup -1} s{sup -1}, while this reaction for 3-ClBzA was too slow to be registered. In the presence of N{sub 2}O the degradation rates induced by gamma radiation were very similar for all chlorobenzoic acids, yet the chloride formation was distinctly higher for 3-ClBzA. In the presence of oxygen the initial degradation of 2-and 4-ClBzA equaled the OH-radical concentration, whereas in case of 3-ClBzA only approx60% of {sup c}entre dotOH led to degradation. The order for the efficiency of dehalogenation was 4->2->3-ClBzA. Several primary radiolytic products could be detected by HPLC. To evaluate the toxicity of final products a bacterial bioluminescence test was carried out.

Non-gaseous radiolysis products of 6-aminopenicillanic acid and potassium salt of benzylepenicillin

International Nuclear Information System (INIS)

Dziegielewski, J.; Jezowska-Trzebiatowska, B.; Siemion, I.Z.

1974-01-01

The radiolysis products of 6-aminopenicillanic acid (6-APA) and potassium salt of benzylpenicillin G, irradiated with γ-rays were separated by the extraction methods and chromatographically by the thin-layer method. On the basis of the IR and UV spectroscopic investigations as well as by the NMR and mass spectrometry methods of the radiolysis products, the paths of the radiation decomposition of 6-APA and of penicillin G were determined. (author)

Fuel-coolant interactions: preliminary experiments on the effect of gases dissolved in the 'coolant'

International Nuclear Information System (INIS)

Asher, R.C.; Davies, D.; Jones, P.G.

1976-12-01

A simple apparatus has been used to study fuel-coolant interactions under reasonably well controlled conditions. Preliminary experiments have used water as the 'coolant' and molten tin at 800 0 C as the 'fuel' and have investigated how the violence of the interaction is affected by dissolving gases (oxygen, nitrogen, carbon dioxide and nitrous oxide) in the water. It was found that saturating the water with carbon dioxide or nitrous oxide completely suppresses the violent interaction. Experiments in which the concentrations of these gases were varied showed that a certain critical concentration was needed; below this concentration the dissolved gas has no significant effect but above it the suppression is

Feasibility study on the type of KALIMER coolant circulation pump

International Nuclear Information System (INIS)

Nam, H. Y.; Kim, Y. K.; Lee, Y. B.; Hwang, J. S.; Choi, S. K.

1997-07-01

The characteristics of mechanical pump and electromagnetic (EM) pump for liquid sodium coolant in a liquid metal reactor are compared and analysed as a design concept of KALIMER coolant pumps. The type of coolant circulation pump affects the selection of reactor type, economics, and reliability of reactor. Though the mechanical pump has much application experience and give satisfaction to the reliability of developed reactor type, the possibility of development is limited and its large weight and volume have a negative effect on the design of the economical liquid metal reactor. The large scale electromagnetic pump has not been verified yet, but it is expected to be demonstrated in time. Because the size of EM pump is small relative to the mechanical pump, the compact reactor design is possible. Therefore the selection of EM pump can be one of the methods to improve the economics. Since the shape of EM pump can be varied according to the arrangement of electromagnet coils, a new or unique reactor type can be developed easily in the process of KALIMER development. In the view point of economic LMR development, it is desirable to adopt the electromagnetic pump. (author). 50 refs., 11 tabs., 24 figs

Redox chemistry of orange I and orange II: a pulse radiolysis study

International Nuclear Information System (INIS)

Yadav, P.; Sharma, K.K.; Rao, B.S.M.; O'Neill, P.; Oakes, J.; Batchelor, S.N.

2004-01-01

The relative reactivities of different tautomeric forms of model azo dyes (Orange I and Orange II) with oxidising and reducing radicals are investigated using pulse radiolysis technique. The rate of the reaction of N 3 with Orange I is diffusion controlled and the order of the reactivity among the tautomers is common ion > hydrazone > azo, whereas a reverse trend was seen in the reaction of e aq . The reducing alcohol radicals react with Orange II with k values in the range (1-3) x 10 9 dm 3 mol -1 s -1 . The relevant reaction mechanism is discussed. (author)

Air effect on polycarbonate radiolysis

International Nuclear Information System (INIS)

Terence, Mauro C.; Araujo, Elmo S.; Guedes, Selma M.L.

1995-01-01

The formation and decay of radicals in the radiolysis of new type of polycarbonate (G scission = 0,73) was investigated by electron spin resonance spectroscopy in the presence and absence of air at room temperature. The air does not interfere in the formation of radicals because they are formed as consequence of direct interaction of radiation. But the air interferes in their decays. During the irradiation the air reacts with all isopropyl radicals and with 2/3 of phenoxy + phenyl radicals. (author). 5 refs., 3 figs

Study on primary coolant system depressurization effect factor in pressurized water reactor

International Nuclear Information System (INIS)

Ji Duan; Cao Xuewu

2006-01-01

The progression of high-pressure core melting severe accident induced by very small break loss of coolant accident plus the loss of main feed water and auxiliary feed water failure is studied, and the entry condition and modes of primary cooling system depressurization during the severe accident are also estimated. The results show that the temperature below 650 degree C is preferable depressurization input temperature allowing recovery of core cooling, and the available and effective way to depressurize reactor cooling system and to arrest very small break loss of coolant accident sequences is activating pressurizer relief valves initially, then restoring the auxiliary feedwater and opening the steam generator relief valves. It can adequately reduce the primary pressure and keep the capacity loop of long-term core cooling. (authors)

Characterisation and activation of catalysts for recombination of radiolysis gas; Charakterisierung und Aktivierung von Katalysatoren zur Rekombination von Radiolysegas

Energy Technology Data Exchange (ETDEWEB)

Bolz, Michael; Koehler, Jan; Schorle, Rolf; Helf, Achim [EnBW Kernkraft GmbH, Philippsburg (Germany). Kernkraftwerk Philippsburg, Teilbereich Chemie

2011-07-01

Radiolysis gas is produced by radiolysis of cooling water during the operation of boiling water reactors. Small amounts of radiolysis gas can accumulate at dead ends of pipes in the water-steam circuit. Under certain conditions, it can accumulate even to higher concentrations. To avoid these accumulations, small catalysts are built in. As part of a diploma thesis, the catalysts were analysed and characterised. (orig.)

Hydrogen peroxide kinetics in water radiolysis

Science.gov (United States)

Iwamatsu, Kazuhiro; Sundin, Sara; LaVerne, Jay A.

2018-04-01

The kinetics of the formation and reaction of hydrogen peroxide in the long time γ- radiolysis of water is examined using a combination of experiment with model calculations. Escape yields of hydrogen peroxide on the microsecond time scale are easily measured with added radical scavengers even with substantial amounts of initial added hydrogen peroxide. The γ-radiolysis of aqueous hydrogen peroxide solutions without added radical scavengers reach a steady state limiting concentration of hydrogen peroxide with increasing dose, and that limit is directly proportional to the initial concentration of added hydrogen peroxide. The dose necessary to reach that limiting hydrogen peroxide concentration is also proportional to the initial concentration, but dose rate has a very small effect. The addition of molecular hydrogen to aqueous solutions of hydrogen peroxide leads to a decrease in the high dose limiting hydrogen peroxide concentration that is linear with the initial hydrogen concentration, but the amount of decrease is not stoichiometric. Proton irradiations of solutions with added hydrogen peroxide and hydrogen are more difficult to predict because of the decreased yields of radicals; however, with a substantial increase in dose rate there is a sufficient decrease in radical yields that hydrogen addition has little effect on hydrogen peroxide decay.

The electrochemistry of IGSCC mitigation in BWR coolant circuits

International Nuclear Information System (INIS)

Macdonald, D.D.

2002-01-01

A brief review is presented of the electrochemical mitigation of IGSCC in water-cooled reactor heat transport circuit structural materials. Electrochemical control and mitigation is possible, because of the existence of a critical potential for IGSCC and by the feasibility of modifying the environment to displace the corrosion potential (ECP) to a value that is more negative than the critical value. However, even in cases where the ECP cannot be displaced sufficiently in the negative direction to become more negative than the critical potential, considerable advantage is accrued, because of the roughly exponential dependence of crack growth rate on potential. The most important parameters in affecting electrochemical control over the ECP and crack growth rate are the kinetic parameters (exchange current densities and Tafel constants) for the redox reactions involving the principal radiolysis products of water (O 2 , H 2 , H 2 O 2 ), external solution composition (concentrations of O 2 , H 2 O 2 , and H 2 ), flow velocity, and the conductivity of the bulk environment. The kinetic parameters for the redox reactions essentially determine the charge transfer impedance of the steel surface, which is shown to be one of the key parameters in affecting the magnitude of the coupling current and hence the crack growth rate. The exchange current densities, in particular, are amenable to control by catalysis or inhibition, with the result that surface modification techniques are highly effective in controlling and mitigating IGSCC in reactor coolant circuit materials. (authors)

CANDU with supercritical water coolant: conceptual design features

International Nuclear Information System (INIS)

Spinks, N.

1997-01-01

An advanced CANDU reactor, with supercritical water as coolant, has many attractive design features. The pressure exceeds 22 MPa but coolant temperatures in excess of 370 degrees C can be reached without encountering the two-phase region with its associated fuel-dry-out and flow-instability problems. Increased coolant temperature leads to increased plant thermodynamic efficiency reducing unit energy cost through reduced specific capital cost and reduced fueling cost. Increased coolant temperature leads to reduced void reactivity via reduced coolant in-core density. Light water becomes a coolant option. To preserve neutron economy, an advanced fuel channel is needed and is described below. A supercritical-water-cooled CANDU can evolve as fuel capabilities evolve to withstand increasing coolant temperatures. (author)

Development of subpicosecond pulse radiolysis system

International Nuclear Information System (INIS)

Kozawa, T.; Saeki, A.; Okamoto, K.; Numata, Y.; Kaseda, K.; Yamamoto, T.; Suemine, S.; Yoshida, Y.; Tagawa, S.

2000-01-01

Subpicosecond pulse radiolysis system was developed to elucidate the primary processes of radiation chemistry in the time region of femtosecond. The system consists of a femtosecond electron linac as an irradiation source, a femtosecond laser as an analyzing light and a jitter compensation system which was designed to reduce the effect of jitter between an electron pulse and a laser pulse on the time resolution. The time resolution of 800 fs was achieved. (author)

Nitrogen oxidative activation in the radiolysis process of dioxide hydrocarbon composition, oxygen-nitrogen over 3-d transition metals

International Nuclear Information System (INIS)

Rustamov, V.R.; Garibov, A.A.; Kerimov, V.K.; Aliyev, S.M.; Nasirova, Kh.Y.

2004-01-01

The radiochemical process of nitrogen fixation in carbon dioxide, oxygen-nitrogen composition in 3-d metal (iron, nickel) was studied. Bifunctional character of surface's role in the generation of radiolysis products was postulated: a) Chemisorption's of molecular ions (N 2 + , CO 2 + , O 2 + ) on the surface of metal and their dissociative neutralization. b) Coordination of nitrogen and carbon oxide being generated in nitrosyl and carbonyl-nitrosyl complex of iron and nickel. Total yield of the products is over the rang 6,4†7,5, to explain radiolysis' what contribution of only neutral products is impossible. Evidently in the generation of final products, defined contribution brings in molecular ions N 2 + (N + ) and CO 2 + . Interaction character of these ions with nickel proposes the formation of the relation between unpaired electrons N 2 + and CO 2 + with unfilled d-sub level of this metals with the nickel nitride generation [N i -N=N + ] and binding energy in ion diazotate decreases to twice. The yield of nitrogen dioxide on radiolysis of the air gave G NO2 =0,8±0,2 molecule/100eV which is proper to the date in the literature. Kinetic curve appears rapidly in the saturation. Air radiolysis over iron gave the following results: G NO 2 = 2,75 ± 0,25, G N 2 O = 9,0 ± 1,0 molecule/100eV. Thus total yield of radiolysis products is Σ G = 10,5 ± 12,0 molecule/100eV. (author)

Nitrogen oxidative activation in the radiolysis process of dioxide hydrocarbon composition, oxygen-nitrogen over 3-D transition metals

International Nuclear Information System (INIS)

Rustamov, V.R.; Garibov, A.A.; Kerimov, V.K.; Aliyev, S.M.; Nasirova, Kh.Y.

2004-01-01

Full text: The radiochemical process of nitrogen fixation in carbon dioxide, oxygen-nitrogen composition in 3-d metal (iron, nickel) was studied. Bifunctional character of surface's role in the generation of radiolysis products was postulated: a) Chemisorption's of molecular ions (N 2 + , CO 2 + , O 2 + ) on the surface of metal and their dissociative neutralization. b) Coordination of nitrogen and carbon oxide being generated in nitrosyl and carbonyl-nitrosyl complex of iron and nickel. Total yield of the products is over the rang 6,4†7,5, to explain radiolysis' what contribution of only neutral products is impossible. Evidently in the generation of final products, defined contribution brings in molecular ions N 2 + (N + ) and CO 2 + . Interaction character of these ions with nickel proposes the formation of the relation between unpaired electrons N 2 + and CO 2 + with unfilled d-sub level of this metals with the nickel nitride generation [N i -N=N + ] and binding energy in ion diazotate decreases to twice. The yield of nitrogen dioxide on radiolysis of the air gave G NO2 =0,8±0,2 molecule/100eV which is proper to the date in the literature. Kinetic curve appears rapidly in the saturation. Air radiolysis over iron gave the following results: G NO 2 = 2,75 ± 0,25, G N 2 O = 9,0 ± 1,0 molecule/100eV. Thus total yield of radiolysis products is Σ G = 10,5 ± 12,0 molecule/100eV

EXPERIMENTAL STUDY OF LOCAL HYDRODYNAMICS AND MASS EXCHANGE PROCESSES OF COOLANT IN FUEL ASSEMBLIES OF PRESSURIZED WATER REACTORS

Directory of Open Access Journals (Sweden)

S. M. Dmitriev

2016-01-01

Full Text Available The results of experimental studies of local hydrodynamics and mass exchange of coolant flow behind spacer and mixing grids of different structural versions that were developed for fuel assemblies of domestic and foreign nuclear reactors are presented in the article. In order to carry out the study the models of the following fuel assemblies have been fabricated: FA for VVER and VBER, FA-KVADRAT for PWR-reactor and FA for KLT-40C reactor. All the models have been fabricated with a full geometrical similarity with full-scale fuel assemblies. The study was carried out by simulating the flow of coolant in a core by air on an aerodynamic test rig. In order to measure local hydrodynamic characteristics of coolant flow five-channel Pitot probes were used that enable to measure the velocity vector in a point by its three components. The tracerpropane method was used for studying mass transfer processes. Flow hydrodynamics was studied by measuring cross-section velocities of coolant flow and coolant rates according to the model cells. The investigation of mass exchange processes consisted of a study of concentration distribution for tracer in experimental model, in determination of attenuation lengths of mass transfer processes behind mixing grids, in calculating of inter-cellar mass exchange coefficient. The database on coolant flow in fuel assemblies for different types of reactors had been accumulated that formed the basis of the engineering substantiation of reactor cores designs. The recommendations on choice of optimal versions of mixing grids have been taken into consideration by implementers of the JSC “OKBM Afrikantov” when creating commissioned fuel assemblies. The results of the study are used for verification of CFD-codes and CFD programs of detailed cell-by-cell calculation of reactor cores in order to decrease conservatism for substantiation of thermal-mechanical reliability.

Nuclear reactor coolant channels

International Nuclear Information System (INIS)

Macbeth, R.V.

1978-01-01

A nuclear reactor coolant channel is described that is suitable for sub-cooled reactors as in pressurised water reactors as well as for bulk boiling, as in boiling water reactors and steam generating nuclear reactors. The arrangement aims to improve heat transfer between the fuel elements and the coolant. Full constructional details are given. See also other similar patents by the author. (U.K.)

Construction of ion beam pulse radiolysis system

Energy Technology Data Exchange (ETDEWEB)

Chitose, Norihisa; Katsumura, Yosuke; Domae, Masafumi; Ishigure, Kenkichi; Murakami, Takeshi [Tokyo Univ. (Japan)

1996-10-01

An ion beam pulse radiolysis system has been constructed at HIMAC facility. Ion beam of 24 MeV He{sup 2+} with the duration longer than 1 {mu}s is available for irradiation. Three kinds of aqueous solutions, (C{sub 6}H{sub 5}){sub 2}CO, NaHCO{sub 3} and KSCN, were irradiated and the absorption signals were observed. (author)

The effect of temperature on radiolysis of iodide ion diluted aqueous solutions

International Nuclear Information System (INIS)

Gorbovitskaya, T.; Tiliks, J.

1996-01-01

In order to investigate the radiolysis of iodine containing aqueous solutions a flow type facility - Iodine Thermoradiation Facility (ITF) has been designed. It has a possibility to irradiate aqueous solutions in the steel vessel with 60 Co γ-rays and continuously (on line) to analyze the products of radiolysis both in liquid and in gaseous phases. By means of ITF the formation of I ox (I 2 + I 3 - + HOI), IO 3 - , H 2 O 2 was studied in 10 -5 - 10 -3 mol/dm 3 CsI aqueous solutions by their radiolysis at dose rate 4.5 kGv/h for six hours in region of temperatures from 313 to 404 K. Under similar conditions, some experiments in glass ampoules were also performed. The steady-state concentrations of I ox and IO 3 - decreased with increasing temperature as linear function of inverted temperature. The effect decreased with decreasing concentration of iodide ion. As the result, at high temperatures (T≥380 K) the steady-state concentration of I ox does not depend essentially on the iodide ion initial concentration. Molecular iodine (I 2 ) released from the solution was the main radiolysis product in gaseous phase. Its steady-state concentration increased with increasing temperature because of iodine solubility in the water and decreased at the same time because the radiolytic iodine concentrations decreased. Therefore the most volatility of irradiated 10 -3 and 10 -4 M CsI solutions was observed at the temperature about 350 K. The volatility of 10 -5 M solutions gradually decreased with increasing temperature. The experimental data were explained on the base of the hypothesis that the reaction between I 2 and radiolytic H 2 O 2 was the limit one determining the temperature dependence of I ox and IO 3 - steady-state concentrations. Its activation energy was estimated to be 27,5 kcal.mol -1 . The temperature dependence for reaction (IO - + H 2 O 2 ) was also estimated. (author) 8 figs., 1 tab., 17 refs

Decomposition of PCBs in oils using gamma radiolysis

International Nuclear Information System (INIS)

Mincher, B.J.; Arbon, R.E.; Schwendiman, G.L.

1996-01-01

This paper investigates the radiolysis of the polychlorinated biphenyls (PCBs) in several oil matrices. The results of mechanism and kinetic studies in isooctane are presented. The decomposition of PCBs in isooctane is shown to occur by reductive dechlorination due to electron capture and to proceed with pseudo-first-order kinetics. The rate is dependent on the initial PCB concentration. Electron capture detection gas chromatograms confirm that dechlorination also occurs with commercial Aroclor PCBs in irradiated transformer and hydraulic oils. The results of a demonstration experiment involving PCB contaminated waste hydraulic oils are presented

Flow boiling test of GDP replacement coolants

International Nuclear Information System (INIS)

Park, S.H.

1995-01-01

The tests were part of the CFC replacement program to identify and test alternate coolants to replace CFC-114 being used in the uranium enrichment plants at Paducah and Portsmouth. The coolants tested, C 4 F 10 and C 4 F 8 , were selected based on their compatibility with the uranium hexafluoride process gas and how well the boiling temperature and vapor pressure matched that of CFC-114. However, the heat of vaporization of both coolants is lower than that of CFC-114 requiring larger coolant mass flow than CFC-114 to remove the same amount of heat. The vapor pressure of these coolants is higher than CFC-114 within the cascade operational range, and each coolant can be used as a replacement coolant with some limitation at 3,300 hp operation. The results of the CFC-114/C 4 F 10 mixture tests show boiling heat transfer coefficient degraded to a minimum value with about 25% C 4 F 10 weight mixture in CFC-114 and the degree of degradation is about 20% from that of CFC-114 boiling heat transfer coefficient. This report consists of the final reports from Cudo Technologies, Ltd

The radiolysis of uracil in oxygenated aqueous solutions. A study by product analysis and pulse radiolysis

International Nuclear Information System (INIS)

Schuchnmann, M.N.; Sonntag, C. von

1983-01-01

Hydroxyl radicals are generated by the radiolysis of N 2 O-O 2 (4:1 v/v)-saturated aqueous solutions of uracil. They add to the 5,6-double bond of the substrate. These radicals are converted by oxygen into the corresponding peroxyl radicals (I) and (II), respectively. Peroxyl radical (I) undergoes a base-induced O 2 - elimination. As an intermediate 5-hydroxyisopyrimidine is formed which rearranges into isobarbituric acid and adds water forming 5,6-dihydro-5,6-dihydroxyuracil. Competing with this base-induced reaction of radical (I) there is a bimolecular decay of radicals (I) and (II). These processes become predominant at low pH. For this reason a strong pH dependence of G (products) is observed. The major products are (G values at pH 3 and 10 in parentheses) 5,6-dihydroxy-5,6-dihydrouracil (1.1; 2.4), isobarbituric acid (0; 1.2), N-formyl-5-hydroxyhydantoin (1.6; 0.2), 5-hydroxybarbituric acid (0.9; 0.2). 5-Hydroxybarbituric acid is formed in its keto form. Its deprotonation has been followed by pulse conductometry. Details of the reaction mechanism, e.g. the involvement of oxyl radicals in the bimolecular decay of (I) and (II), are discussed. (author)

Stress Analysis of Fuel Rod under Axial Coolant Flow

Energy Technology Data Exchange (ETDEWEB)

Jin, Hai Lan; Lee, Young Shin; Lee, Hyun Seung [Chungnam National University, Daejeon (Korea, Republic of); Park, Num Kyu; Jeon, Kyung Rok [Kerea Nuclear Fuel., Daejeon (Korea, Republic of)

2010-05-15

A pressurized water reactor(PWR) fuel assembly, is a typical bundle structure, which uses light water as a coolant in most commercial nuclear power plants. Fuel rods that have a very slender and long clad are supported by fuel assembly which consists of several spacer grids. A coolant is a fluid which flows through device to prevent its overheating, transferring the heat produced by the device to other devices that use or dissipate it. But at the same time, the coolant flow will bring out the fluid induced vibration(FIV) of fuel rods and even damaged the fuel rod. This study has been conducted to investigate the flow characteristics and nuclear reactor fuel rod stress under effect of coolant. Fluid structure interaction(FSI) analysis on nuclear reactor fuel rod was performed. Fluid analysis of the coolant which flow along the axial direction and structural analysis under effect of flow velocity were carried out under different output flow velocity conditions

Stress Analysis of Fuel Rod under Axial Coolant Flow

International Nuclear Information System (INIS)

Jin, Hai Lan; Lee, Young Shin; Lee, Hyun Seung; Park, Num Kyu; Jeon, Kyung Rok

2010-01-01

A pressurized water reactor(PWR) fuel assembly, is a typical bundle structure, which uses light water as a coolant in most commercial nuclear power plants. Fuel rods that have a very slender and long clad are supported by fuel assembly which consists of several spacer grids. A coolant is a fluid which flows through device to prevent its overheating, transferring the heat produced by the device to other devices that use or dissipate it. But at the same time, the coolant flow will bring out the fluid induced vibration(FIV) of fuel rods and even damaged the fuel rod. This study has been conducted to investigate the flow characteristics and nuclear reactor fuel rod stress under effect of coolant. Fluid structure interaction(FSI) analysis on nuclear reactor fuel rod was performed. Fluid analysis of the coolant which flow along the axial direction and structural analysis under effect of flow velocity were carried out under different output flow velocity conditions

Radiolysis of kaempferol in water/methanol mixtures. Evaluation of antioxidant activity of kaempferol and products formed.

Science.gov (United States)

Marfak, Abdelghafour; Trouillas, Patrick; Allais, Daovy-Paulette; Champavier, Yves; Calliste, Claude-Alain; Duroux, Jean-Luc

2003-02-26

Oxidative reaction between hydroxymethyl radical ((*)CH(2)OH) and kaempferol, in methanol and methanol/water mixtures, was studied by gamma-radiolysis using a (60)Co source. Radiolysis was performed with concentrations and doses ranging from 5 x 10(-)(5) M to 5 x 10(-)(3) M and from 0.5 kGy to 14 kGy, respectively. Kaempferol degradation was followed by HPLC. Results showed that (*)CH(2)OH reacts with kaempferol at the 3-OH group and produces two depsides (K1 and K2) and other products including K3. K1, K2, and K3 were identified by NMR, LC-MS, and HRMS. The kaempferol degradation pathway leading to the K1, K2, and K3 formation is proposed. It was observed that the more water concentration in the irradiation medium increases, the more K2 concentration increases. Comprehension of food preservation is not clear because many phenomena occurring during irradiation are not established. Radiolysis of kaempferol in water/methanol mixtures helps to elucidate the phenomenon and it is possible that during the treatment of nutriments by gamma-irradiation, a series of products such as depside K2 could be formed. Antioxidant properties of kaempferol radiolysis products were evaluated according to their capacity to decrease the EPR DPPH (1,1-diphenyl-2-picrylhydrazil) signal and to inhibit superoxide radicals formed by the enzyme reaction "xanthine + xanthine oxidase".

Improving Coolant Effectiveness through Drill Design Optimization in Gundrilling

Science.gov (United States)

Woon, K. S.; Tnay, G. L.; Rahman, M.

2018-05-01

Effective coolant application is essential to prevent thermo-mechanical failures of gun drills. This paper presents a novel study that enhances coolant effectiveness in evacuating chips from the cutting zone using a computational fluid dynamic (CFD) method. Drag coefficients and transport behaviour over a wide range of Reynold numbers were first established through a series of vertical drop tests. With these, a CFD model was then developed and calibrated with a set of horizontal drilling tests. Using this CFD model, critical drill geometries that lead to poor chip evacuation including the nose grind contour, coolant hole configuration and shoulder dub-off angle in commercial gun drills are identified. From this study, a new design that consists a 20° inner edge, 15° outer edge, 0° shoulder dub-off and kidney-shaped coolant channel is proposed and experimentally proven to be more superior than all other commercial designs.

GC-FTIR-MS analysis of volatile radiolytic products in the radiolysis of nitroaniline

International Nuclear Information System (INIS)

Kuruc, J.; Sahoo, M.K.; Kubinec, R.

1993-01-01

A good deal of products formed in the γ-radiolysis of isomeric nitroaniline solutions in carbon tetrachloride have been identified using GC-FTIR-MS technique. Tetrachloroethylene, chlorobenzene, hexachloroethane isomeric di-, tri- and tetrachlorobenzenes and chloroisocyanatobenzenes are among the important products formed in the radiolysis. Formation of dichlorobenzene is the result of ipso-substitution of both the nitro and aniline group by chlorine atom and the subsequent chloration of dichlorobenzene results in the formation of polychlorobenzenes. Chloroisocyanatobenzene is proposed to be the product arising from the interaction of dichlorocarbene and the nitro group of nitroaniline followed by chlorination of the resulting product, isocyanatobenzene. A 94% yield of undissolved 1,2-aminonitrobenzene chloride salt is obtained from the radiolysis of o-nitroaniline solution in carbon tetrachloride with a radiation yield of 1.83 molecules per 100 eV absorbed energy for an irradiation dose of 267 kGy. (author) 9 refs.; 3 figs.; 2 tabs

Regularities of radiolysis of carbon dioxide adsorbed on Zeokar-2 catalyst

International Nuclear Information System (INIS)

Rustamov, V.R.; Kurbanov, M.A.; Kerimov, V.K.; Musaeva, P.F.

1982-01-01

Kinetics of CO formation, effect of dose rate and adsorbed water on CO yield during heterogeneous gamma-radiolysis of CO 2 have been studied. Radiation-chemical yields of the products are determined. The mechanism of reactions is discussed. It is shown that the catalyst plays the role of acceptor of active intermediate particles (O - and others) and acts as a chemical reagent

Gamma radiolysis effects on basalt groundwater

International Nuclear Information System (INIS)

Gray, W.J.

1983-10-01

Gamma radiolysis of basalt groundwater containing 700 ppM methane produces a milky liquid that is a suspension of fine particles of a high molecular weight hydrocarbon somewhat like polyethylene. The ability of these polymers to chelate with, or otherwise sorb, metal ions from aqueous solution was measured using Cu +2 as a representative cation. Values in the range 0.3 to 0.8 millimoles of Cu per liter of solution were found. 5 references, 2 figures, 2 tables

Experiments about the integrity of BWR relief pipes in postulated radiolysis gas combustion. Scenario No.2. Minor steam leakages without any lowering of the water level

International Nuclear Information System (INIS)

Friedrich, A.; Grune, J.; Sempert, K.; Stern, G.; Kuznetsov, M.; Redlinger, R.; Breitung, W.; Franke, T.

2008-01-01

The experiments described in this article were performed to study this comprehensive radiolysis gas scenario: - The relief pipe is filled completely with radiolysis gas (2H 2 +O 2 ). - After opening of the S and R valve, the radiolysis gas is compressed adiabatically by the incoming steam without mixing. - Roughly at the point of peak pressure in the relief pipe (20 bar) the radiolysis gas ignites. This dynamic scenario was studied in steady-state model experiments with a test pipe which corresponds to the relief pipes installed in KKP-1 in terms of materials, dimensions, and manufacturing control. The initial conditions and boundary conditions of the experiments were conservative. In the course of the tests, the maximum dynamic strain and the residual plastic deformation of the test pipe were measured via the transient detonation load. The maximum dynamic strain measured was 0.75%, the maximum residual plastic strain reached 0.15%. The pipe suffered no other deformation above and beyond this slight plastic strain. The radiolysis gas detonation was simulated very well numerically. Using the calculated pressure loads in a structural dynamics model also showed good agreement with the measured maximum dynamic pipe strains. In this way, the experimental findings were confirmed theoretically. The experiments and the calculations showed that postulated radiolysis gas reactions during pressure relief cannot jeopardize the integrity of the relief pipe. (orig.)

Coolant make-up device for BWR type reactor

International Nuclear Information System (INIS)

Sasagawa, Hiroshi.

1994-01-01

In a coolant make-up device, an opening of a pressure equalizing pipeline in a pressure vessel is disposed in coolants above a reactor core and below a usual fluctuation range of a reactor vessel water level. Further, a float check valve is disposed to the pressure equalizing pipeline for preventing coolants in the pressure vessel flowing into the pipeline. If the water level in the pressure vessel is lowered than the setting position for the float check valve, the float drops by its own weight to open the opening of the pressure equalizing pipeline. Then, steams in the pressure vessel are flown into the pipeline, to equalize the pressure between a coolant storage tank and the pressure vessel of the reactor. Coolants in the coolant storage tank is injected to the pressure vessel by way of the water injection pipeline due to the difference of the pressure head between the water level in the coolants storage tank and the water level in the pressure vessel. If the coolants are lowered than the setting position for the float check value, the float check valve does not close unless the water level is recovered to the setting position for the float valve and, accordingly, the coolant make-up is continued. (N.H.)

Precursor of fragment radicals in the radiolysis of normal alkanes. [Gamma radiation

Energy Technology Data Exchange (ETDEWEB)

Isildar, M; Schuler, R H [Carnegie-Mellon Univ., Pittsburgh, Pa. (USA). Dept. of Chemistry

1978-01-01

It is found that the yields of fragment radicals produced in the radiolysis of n-hexane are not significantly affected by the changes in the ion recombination processes that occur when HI is added to the system. From this observation it is concluded that in the radiolysis of normal alkanes, carbon-carbon bond rupture results predominantly either from high energy processes that do not directly involve ionic precursors or, more likely, from the dissociation of the initial ions at very early times (< 10/sup -11/s) before a substantial fraction of the geminate ions undergo neutralization.

Studies of iodine adsorption and desorption on HTGR coolant circuit materials

International Nuclear Information System (INIS)

Osborne, M.F.; Compere, E.L.; de Nordwall, H.J.

1976-04-01

Safety studies of the HTGR system indicate that radioactive iodine, released from the fuel to the helium coolant, may pose a problem of concern if no attenuation of the amount of iodine released occurs in the coolant circuit. Since information on iodine behavior in this system was incomplete, iodine adsorption on HTGR materials was studied in vacuum as a function of iodine pressure and of adsorber temperature. Iodine coverages on Fe 3 O 4 and Cr 2 O 3 approached maxima of about 2 x 10 14 and 1 x 10 14 atoms/cm 2 , respectively, whereas the iodine coverage on graphite under similar conditions was found to be less by a factor of about 100. Iodine desorption from the same materials into vacuum or flowing helium was investigated, on a limited basis, as a function of iodine coverage, of adsorber temperature, and of dry vs wet helium. The rate of vacuum desorption from Fe 3 O 4 was related to the spectrum of energies of the adsorption sites. A small amount of water vapor in the helium enhanced desorption from iron powder but appeared to have less effect on desorption from the metal oxides

Spin trapping of cyanoalkyl radicals in the liquid phase γ radiolysis of nitriles

International Nuclear Information System (INIS)

Mao, S.W.; Kevan, L.

1976-01-01

The following radicals have been identified in the liquid phase γ radiolysis of several nitriles by spin trapping with phenyl tert-butyl nitrone: CH 2 CN in acetonitrile, H and CH 3 CHCN(question) in propionitrile, CH(CN) 2 in malononitrile, and H, CN, and CH 2 CH 2 CN in succinonitrile. γ proton splittings are observed for the CH 2 CN and CH(CH) 2 spin adducts. The results are discussed in comparison with solid phase radiolysis data and with alkyl radical spin adduct splittings

Pulse radiolysis studies of mangiferin: A C-glycosyl xanthone isolated from Mangifera indica

International Nuclear Information System (INIS)

Mishra, B.; Priyadarsini, K.Indira; Sudheerkumar, M.; Unnikrishhnan, M.K.; Mohan, H.

2006-01-01

Pulse radiolysis technique has been employed to study the reaction of different oxidizing and reducing radicals with mangiferin. The reaction of · OH radical showed the formation of transient species absorbing in 380-390 and 470-480 nm region. The reaction with specific one-electron oxidants (N 3 · , CCl 3 O 2 · ) also showed the formation of similar transient absorption bands and is assigned to phenoxyl radicals. The pK a values of the transient species have been determined to be 6.3 and 11.9. One-electron oxidation potential of mangiferin at pH 9 has been found to be 0.62 V vs. NHE. The reaction of e aq - showed the formation of transient species with λ max at 340 nm, which is assigned to the ketyl anion radical formed on addition of e aq - at carbonyl site. Reactions of one-electron oxidised mangiferin radicals with ascorbic acid have also been studied

Pulse radiolysis studies of mangiferin: A C- glycosyl xanthone isolated from Mangifera indica

Science.gov (United States)

Mishra, B.; Priyadarsini, K. Indira; Sudheerkumar, M.; Unnikrishhnan, M. K.; Mohan, H.

2006-01-01

Pulse radiolysis technique has been employed to study the reaction of different oxidizing and reducing radicals with mangiferin. The reaction of rad OH radical showed the formation of transient species absorbing in 380-390 and 470-480 nm region. The reaction with specific one-electron oxidants (N 3rad , CCl 3O 2rad ) also showed the formation of similar transient absorption bands and is assigned to phenoxyl radicals. The p Ka values of the transient species have been determined to be 6.3 and 11.9. One-electron oxidation potential of mangiferin at pH 9 has been found to be 0.62 V vs. NHE. The reaction of e aq- showed the formation of transient species with λmax at 340 nm, which is assigned to the ketyl anion radical formed on addition of e aq- at carbonyl site. Reactions of one-electron oxidised mangiferin radicals with ascorbic acid have also been studied.

The analysis of radiolysis impurities in 18F-FDG and methods of repurification

International Nuclear Information System (INIS)

Jinming Zhang; Yungang Li; Jian Liu; Xiaojun Zhang; Jiahe Tian

2010-01-01

To investigate the radio impurity in the radiolysis of 18 F-FDG at high radiodose and radioconcentrated solutions and develop methods of repurification. The radiolysis of 18 F-FDG was analyzed by TLC. The radio-impurity was confirmed by biodistribution and small animal PET/CT studies. 18 F-FDG was unstable at high radioconcentration over 37 GBq/mL or under basic condition. TLC, biodistribution and PET/CT all indicated that the main autoradiolysis byproduct was free fluoride ion. The radiolyzed 18 F-FDG was repurified by solid-phase extraction (SPE) column. The repurified 18 F-FDG had a radiochemical purity (RCP) of over 99% and significantly lower bone uptake than that was before repurification (P = 0.0003). There was a positive correlation between the recovery yield and the purity of 18 F-FDG (R 2 = 0.66). (author)

Reactor coolant cleanup device

International Nuclear Information System (INIS)

Igarashi, Noboru.

1986-01-01

Purpose: To enable to introduce reactor water at high temperature and high pressure as it is, as well as effectively adsorb to eliminate cobalt in reactor water. Constitution: The coolant cleanup device comprises a vessel main body inserted to coolant pipeway circuits in a water cooled reactor power plant and filters contained within the vessel main body. The filters are prepared by coating and baking powder of metal oxides such as manganese ferrite having a function capable of adsorbing cobalt in the coolants onto the surface of supports made of metals or ceramics resistant to strong acids and alkalies in the form of three-dimensional network structure, for example, zircaloy-2, SUS 303 and the zirconia (baking) to form a basic filter elements. The basic filter elements are charged in plurality to the vessel main body. (Kawaiami, Y.)

Analysis of Coolant Options for Advanced Metal Cooled Nuclear Reactors

National Research Council Canada - National Science Library

Can, Levent

2006-01-01

.... The overall focus of this study is the build up of induced radioactivity in the coolant of metal cooled reactors as well as the evaluation of other physical and chemical properties of such coolants...

Effects of the radiolysis products of sennoside A on HepG2 and PC-3 cell

International Nuclear Information System (INIS)

Kim, Dong Ho; Jo, Min Ho

2016-01-01

Radiolysis of sennoside A was carried out by gamma irradiation and the anti-cancer activities of the radiolysis product were evaluated. An aqueous solution of sennoside A was exposed to 0.5-3 kGy of gamma irradiation and the radiolysis products were analyzed by HPLC. A fraction of radiolysis product (RLF) of sennoside A was isolated and the RLF was presumed as a rhein-8-β-D-glucoside. The anticancer effect of the RLF was compared with the sennoside and rhein using a in vitro assay system of human prostate cancer cells (PC-3) and human hepatoma HepG2 cells. The cell viability of PC-3 and HepG2 cell was significantly decreased to 12.4±1.2% and 32.4±2.1%, respectively, by the treatment of 0.6 μM of RLF. The sennoside A (range from 0 to 25 μM) had no cytotoxic effect on PC-3 and HepG2 cells, while the rhein had the effect on HepG2 cells with a LD_5_0 at 80 μM

Effects of the radiolysis products of sennoside A on HepG2 and PC-3 cell

Energy Technology Data Exchange (ETDEWEB)

Kim, Dong Ho; Jo, Min Ho [Research Division for Biotechnology, Korea Atomic Energy Research Institute, Jeongeup (Korea, Republic of)

2016-11-15

Radiolysis of sennoside A was carried out by gamma irradiation and the anti-cancer activities of the radiolysis product were evaluated. An aqueous solution of sennoside A was exposed to 0.5-3 kGy of gamma irradiation and the radiolysis products were analyzed by HPLC. A fraction of radiolysis product (RLF) of sennoside A was isolated and the RLF was presumed as a rhein-8-β-D-glucoside. The anticancer effect of the RLF was compared with the sennoside and rhein using a in vitro assay system of human prostate cancer cells (PC-3) and human hepatoma HepG2 cells. The cell viability of PC-3 and HepG2 cell was significantly decreased to 12.4±1.2% and 32.4±2.1%, respectively, by the treatment of 0.6 μM of RLF. The sennoside A (range from 0 to 25 μM) had no cytotoxic effect on PC-3 and HepG2 cells, while the rhein had the effect on HepG2 cells with a LD{sub 50} at 80 μM.

Gamma-radiolysis of some glycoproteins in dilute aqueous solutions

Energy Technology Data Exchange (ETDEWEB)

Nagrani, S

1981-01-01

A study has been made of the radiation-induced damage of some glycoproteins in dilute aqueous solutions. By use of specific radical scavengers, the roles of the individual free radicals, formed by ..gamma..-radiolysis, in causing damage has been assessed. The most effective radical in causing damage to human and porcine glycopolypeptide is the OH radical. The structure of the different blood group glycopolypeptides determines the sensitivity towards the free radical attack. The glycopolypeptide shows depolymerization and a characteristic absorption at approximately 270 nm due to the formation of additional products on irradiation. Chemical changes of the irradiated glycopolypeptide solutions revealed significant damage to the oligosaccharide chain and the polypeptide core of the glycopolypeptide. The radiation-induced inactivation of another glycoprotein, external yeast invertase, due to different radical species at pH 7.0 decreases in the following order: ea-barq > OH radical > (SCN) radical/sub 2//sup -/ > Br radical/sub 2//sup -/. The structure of this enzyme, accounts for the mechanism of enzyme inactivation and the relative damage of carbohydrate and amino acid residues. The irradiated enzyme solutions show significant changes in their electrophoretic behaviour on cellogel electrophoresis due to the formation of radiolysis products, which also show characteristic absorption maxima at approximately 275 nm. (author).

Coolant cleanup method in a nuclear reactor

International Nuclear Information System (INIS)

Kubota, Masayoshi; Nishimura, Shigeoki; Takahashi, Sankichi; Izumi, Kenkichi; Motojima, Kenji.

1983-01-01

Purpose : To effectively adsorb to remove low molecular weight organic substances from iron exchange resins for use in the removal of various radioactive nucleides contained in reactor coolants. Method : Reactor coolants are recycled by a main recyling pump in a nuclear reactor and a portion of the coolants is cooled and, thereafter, purified in a coolant desalter. While on the other hand, high pressure steams generated from the reactor are passed through a turbine, cooled in a condensator, eliminated with claddings or the likes by the passage through a filtration desalter using powderous ion exchange resins and then further passed through a desalter (filled with granular ion exchange resins). For instance, an adsorption and removing device for organic substances (resulted through the decomposition of ion exchange resins) precoated with activated carbon powder or filled with granular activated carbon is disposed at the downstream for each of the desalters. In this way, the organic substances in the coolants are eliminated to prevent the reduction in the desalting performance of the ion exchange resins caused by the formation of complexes between organic substances and cobalt in the coolants, etc. In this way, the coolant cleanup performance is increased and the amount of wasted ion exchange resins can be decreased. (Horiuchi, T.)

Study on effects of mixing vane grids on coolant temperature distribution by subchannel analysis

Energy Technology Data Exchange (ETDEWEB)

Mao, H.; Yang, B.W.; Han, B. [Xi' an Jiaotong Univ., Shaanxi (China). Science and Technology Center for Advanced Nuclear Fuel Research

2016-07-15

Mixing vane grids (MVG) have great influence on coolant temperature field in the rod bundle. The MVG could enhance convective heat transfer between the fuel rod wall and the coolant, and promote inter-subchannel mixing at the same time. For the influence of the MVG on convective heat transfer enhancement, many experiments have been done and several correlations have been developed based on the experimental data. However, inter-subchannel mixing promotion caused by the MVG is not well estimated in subchannel analysis because the information of mixing vanes is totally missing in most subchannel codes. This paper analyzes the influence of mixing vanes on coolant temperature distribution using the improved MVG model in subchannel analysis. The coolant temperature distributions with the MVG are analyzed, and the results show that mixing vanes lead to a more uniform temperature distribution. The performances of split vane grids under different power conditions are evaluated. The results are compared with those of spacer grids without mixing vanes and some conclusions are obtained.

Study on effects of mixing vane grids on coolant temperature distribution by subchannel analysis

International Nuclear Information System (INIS)

Mao, H.; Yang, B.W.; Han, B.

2016-01-01

Mixing vane grids (MVG) have great influence on coolant temperature field in the rod bundle. The MVG could enhance convective heat transfer between the fuel rod wall and the coolant, and promote inter-subchannel mixing at the same time. For the influence of the MVG on convective heat transfer enhancement, many experiments have been done and several correlations have been developed based on the experimental data. However, inter-subchannel mixing promotion caused by the MVG is not well estimated in subchannel analysis because the information of mixing vanes is totally missing in most subchannel codes. This paper analyzes the influence of mixing vanes on coolant temperature distribution using the improved MVG model in subchannel analysis. The coolant temperature distributions with the MVG are analyzed, and the results show that mixing vanes lead to a more uniform temperature distribution. The performances of split vane grids under different power conditions are evaluated. The results are compared with those of spacer grids without mixing vanes and some conclusions are obtained.

On the radiolysis of concentrated alkaline and calcium-nitrate solutions

International Nuclear Information System (INIS)

Kiwi, J.T.; Daniels, M.

1978-01-01

Previous studies have shown that more nitrite is produced than can reasonably be accounted for by an indirect radiolysis mechanism based on the radical products of radiolysed water. Further results on the relative roles of indirect effect and direct effect (a chemical transformation in the solute due to its energy absorption) are presented. Major products are nitrite, peroxide and oxygen and yields can be accounted for using the electron fraction model. (author)

A pulse radiolysis study of the reaction of the sulphate radical ion in aqueous solutions of styrene

International Nuclear Information System (INIS)

McAskill, N.A.; Sangster, D.F.

1979-01-01

The ultraviolet absorption spectra of the transient species formed during the pulse radiolysis of styrene and peroxydisulfate solutions showed that a benzyl-type radical was formed from styrene and the SO 4 - radical. The effect of adding Cl - was also studied. These results are in conflict with the claim that a phenylethyl radical was formed from SO 4 - via the styrene cation radical. That study was made on acetonitrile solutions of styrene, S 2 O 8 2- CUCl 2 and LiCl and the present results suggest that up to 70% of the SO 4 - radicals may have been converted into Cl 2 - radical which then reacted with styrene

Free radicals generated by radiolysis of aqueous solutions

International Nuclear Information System (INIS)

Schwarz, H.A.

1981-01-01

The free radicals produced in the radiolysis of aqueous solutions span the range of redox potentials from -2.9 to +2.65 volts. The identity and nature of these radicals were discussed. Most of the discussion was results obtained with low LET radiation sources ( 60 Co gamma radiation or electron accelerators). Water radiolysis provides the synthesis of many radicals and radical ions in aqueous solution. The primary radicals, e/sub aq/ - H, OH, are well characterized. The radical population can be made to be 90% pure OH (or O - ) if N 2 O solutions are irradiated, the remaining 10% being H atoms. 55% of the radicals can be converted to H atoms in acid solution or in neutral phosphate solutions(e/sub aq/ - reacts with H 2 PO 4- to produce H). The remaining 45% (OH radicals) are difficult to convert to H by reaction with H 2 , due to the slow rate of the reaction. About 100 atmospheres of H 2 are required to do the conversion in less than 10 - 6 sec. 3 figures, 3 tables. (DP)

Reactor primary coolant system pipe rupture study. Progress report No. 33, January--June 1975

International Nuclear Information System (INIS)

1975-10-01

The pipe rupture study is designed to extend the understanding of failure-causing mechanisms and to provide improved capability for evaluating reactor piping systems to minimize the probability of failures. Following a detailed review to determine the effort most needed to improve nuclear system piping (Phase 1), analytical and experimental efforts (Phase 2) were started in 1965. This progress report summarizes the recent accomplishments of a broad program in (a) basic fatigue crack growth rate studies focused on LWR primary piping materials in a simulated BWR primary coolant environment, (b) at-reactor tests of the effect of primary coolant environment on the fatigue behavior of piping steels, (c) studies directed at quantifying weld sensitization in Type 304 stainless steel, (d) support studies to characterize the electrochemical potential behavior of a typical BWR primary water environment and (e) special tests related to simulation of fracture surfaces characteristic of IGSCC field failures

Multirods burst tests under loss-of-coolant conditions

International Nuclear Information System (INIS)

Kawasaki, S.; Uetsuka, H.; Furuta, T.

1983-01-01

In order to know the upper limit of coolant flow area restriction in a fuel assembly under loss-of-coolant accidents in LWRs, burst tests of fuel bundles were performed. Each bundle consisted of 49 rods(7x7 rods), and bursts were conducted in flowing steam. In some cases, 4 rods were replaced by control rods with guide tubes in a bundle. After the burst, the ballooning behavior of each rod and the degree of coolant flow area restriction in the bundle were measured. Ballooning behavior of rods and degree of coolant flow channel restriction in bundles with control rods were not different from those without control rods. The upper limit of coolant flow channel restriction under loss-of-coolant conditions was estimated to be about 80%. (author)

Studies of some elementary processes involving electrons in the gas phase by pulse-radiolysis microwave-cavity technique

International Nuclear Information System (INIS)

Sunagawa, Takeyoshi; Makita, Takeshi; Musasa, Hirofumi; Tatsumi, Yoshitsugu; Shimamori, Hiroshi

1995-01-01

The pulse radiolysis-microwave cavity technique has been employed for detection of free electrons in the gas phase. Presented are results of the observation of electron disappearance by attachment to molecules, the electron thermalization (energy loss) processes in the presence of an electron-attaching compound, and the formation of electrons by Penning ionization. (author)

Extended Life Coolant Testing

Science.gov (United States)

2016-06-06

number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. 1. REPORT DATE (DD-MM-YYYY) 06-06-2016 2. REPORT TYPE Interim Report 3. DATES COVERED ... Corrosion Testing of Traditional and Extended Life Coolants 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Hansen, Gregory A. T...providing vehicle specific coolants. Several laboratory corrosion tests were performed according to ASTM D1384 and D2570, but with a 2.5x extended time

Gas generation by self-radiolysis of tritiated waste materials

International Nuclear Information System (INIS)

Tadlock, W.E.; Abell, G.C.; Steinmeyer, R.H.

1980-01-01

Studies simulating the effect of self-radiolysis in disposal packages containing tritiated waste materials show hydrogen to be the dominant gas-phase product. Pressure buildup and gas composition over various tritiated octane and tritiated water samples are designed to give worst case results. One effect of tritium fixation agents is to reduce pressure buildup. The results show that development of explosive gas mixtures is unlikely and that maximum pressure buildup in typical Mound Facility waste packages can be expected to be <0.25 MPa

One-electron oxidation of the hydroquinonic form of vitamin K by OH· and N3· free radicals. A steady-state gamma radiolysis study

International Nuclear Information System (INIS)

Nguyen Van Binh, E.; Gardes-Albert, M.; Ferradini, C.; Acher, F.; Azerad, R.

1991-01-01

The oxidation of a water-soluble model of vitamin K hydroquinone, symbolised by KH 2 p, has been studied by γ radiolysis using OH· or N 3 · free radicals as oxidants. Irradiation doses were up to 300 Gy. The analysis of final products by spectrophotometric absorption and HPLC allowed to characterize the formation of the quinone K and to estimate the initial yield of KH 2 p-disappearance and K-formation. N 3 · radicals led selectively to the formation of the quinone K with a G-value of (3.0 ± 0.3) x 10 -7 mol/J, thus involving a simple one-electron oxidation mechanism. On the contrary, when OH· radicals oxidized KH 2 p, in addition to the quinone, other non identified species were simultaneously produced during the radiolysis, thus requiring a more complex oxidation mechanism [fr

Isotope effect in gamma-radiolysis of absorbed ammonia

Energy Technology Data Exchange (ETDEWEB)

Lyapina, T G; Kotov, A G [Nauchno-Issledovatel' skij Fiziko-Khimicheskij Inst., Moscow (USSR)

1975-07-01

The radiolysis of NH/sub 3/ of various isotopic compounds adsorbed on silica gel or zeolite at 77degK was studied. Experimental data were treated using the kinetic equation dR/dt=GI-kIR where R=radical concentration, G=radical yield, k=radical termination constant and I=radiation dose rate. Both the values of G and R for NH/sub 3/ adsorbed on silica gel are affected by the isotopic effect of /sup 15/N, but not on zeolite. The isotopic effect is explained by the influence of protonated acidity of the silica gel surface.

Pulse radiolysis of catalase in solution: Pt. 1

International Nuclear Information System (INIS)

Gebicka, Lidia; Metodiewa, Diana; Gebicki, J.L.

1989-01-01

The time-course of absorption changes of oxygen-saturated solutions of bovine-liver catalase after pulse radiolysis have been studied. The rate constant of formation of Compound I due to the reaction of catalase with hydrogen peroxide has been estimated to be 2.0 x 10 7 dm 3 mol -1 s -1 . Radiation generated super-oxide radicals reduce Compound I to Compound II with a rate constant of 5.0 x 10 6 dm 3 mol -1 s -1 . The formation of Compound III in the direct reaction of O 2 - with catalase has also been observed. (author)

Limits to fuel/coolant mixing

International Nuclear Information System (INIS)

Corradini, M.L.; Moses, G.A.

1985-01-01

The vapor explosion process involves the mixing of fuel with coolant prior to the explosion. A number of analysts have identified limits to the amount of fuel/coolant mixing that could occur within the reactor vessel following a core melt accident. Past models are reviewed and a sim plified approach is suggested to estimate the upper limit on the amount of fuel/coolant mixing pos sible. The approach uses concepts first advanced by Fauske in a different way. The results indicat that water depth is an important parameter as well as the mixing length scale D /SUB mix/ , and for large values of D /SUB mix/ the fuel mass mixed is limited to <7% of the core mass

Pulse radiolysis for the study of lead salt solutions

International Nuclear Information System (INIS)

Breitenkamp, M.

1976-01-01

The Pb + ions are produced from Pb 2 + in lead perchlorate solutions by reduction with hydrated electrons, and the absorption spectrum of this ion has been measured together with a time differential observation in the micro- and millisecond range of the disparation of these ions from the solution in the presence of different substances. For these studies the method of pulsed radiolysis has been applied, detecting the short lifed intermediate reaction products by optical absorption and electric conductivity measurements. First an attempt has been made to produce the Pb + ions also by reduction of Pb 2 + with H-atoms. If Pb + and H is produced simultaneously in an aqueous solution the reaction Pb + + H -> PbH + can occur. The absorption spectrum of the short lifed species PbH + has been studied together with the second order evanescence. In addition Pb 2 + has been reduced by i-propanol radicals at high Pb 2 + concentrations. The second order evanescence has been observed and the rate constant of the reaction 2Pb + -> Pb + Pb 2 + has been measured. The Pb 2 + ions can also be reduced by CO 2- radicals, which are formed in the presence of formiate. The observations can be interpreted by the assumption of the primary reaction Pb 2 + + CO 2- -> PbCO 2+ . the spectrum of the product PbCO 2+ has been measured. A second order reaction of PbCO 2+ is observed with a resulting unstable particle of the structure Pb 2 CO 2 2 + . Finally the oxidation of Pb + by the OH-radical and by hydrogen peroxide has been studied. (orig./HK) [de

Effect of temperature on the radiolysis of N/sub 2/O/sub 4/ in fast reactors

Energy Technology Data Exchange (ETDEWEB)

Nesterenko, V B; Nichipor, G V; Ukraintseva, L V

1974-01-01

The effects of temperature on radiolysis of gaseous nitrogen tetraoxide in fast reactors on assumption of radical mechanism have been studied. Energy transfer is assumed negligible. Data are obtained with ECM Minsk-22.

Performance investigation of an automotive car radiator operated with nanofluid-based coolants (nanofluid as a coolant in a radiator)

International Nuclear Information System (INIS)

Leong, K.Y.; Saidur, R.; Kazi, S.N.; Mamun, A.H.

2010-01-01

Water and ethylene glycol as conventional coolants have been widely used in an automotive car radiator for many years. These heat transfer fluids offer low thermal conductivity. With the advancement of nanotechnology, the new generation of heat transfer fluids called, 'nanofluids' have been developed and researchers found that these fluids offer higher thermal conductivity compared to that of conventional coolants. This study focused on the application of ethylene glycol based copper nanofluids in an automotive cooling system. Relevant input data, nanofluid properties and empirical correlations were obtained from literatures to investigate the heat transfer enhancement of an automotive car radiator operated with nanofluid-based coolants. It was observed that, overall heat transfer coefficient and heat transfer rate in engine cooling system increased with the usage of nanofluids (with ethylene glycol the basefluid) compared to ethylene glycol (i.e. basefluid) alone. It is observed that, about 3.8% of heat transfer enhancement could be achieved with the addition of 2% copper particles in a basefluid at the Reynolds number of 6000 and 5000 for air and coolant respectively. In addition, the reduction of air frontal area was estimated.

gamma-radiolysis and pulse radiolysis of aqueous 4-chloroanisole

DEFF Research Database (Denmark)

Quint, R.M.; Park, H.R.; Krajnik, P.

1996-01-01

of oxygen leads to its addition on the hydroxpcyclohexadienyl radicals, k(OH-adduct + O-2) = 3.2 x 10(8) dm(3) mol(-1) s(-1). In airfree solution the reaction of H-atom with the substrate, k(H + 4-ClAn) = 1.2 x 10(9) dm(3) mol(-1) s(-1), results in H-adducts which decay in bimolecular reactions, 2k = 8.2 x...... 10(8) dm(2) mol(-1) s(-1). The rate constant for the reaction of the solvated electrons has been determined to k (e(aq)(-) + 4-CIAn) = 2 x 10(9) dm(2) mol(-1) s(-1). The absorption spectra of H- and OH-adducts were measured in the range of 280-450 nm. The products analysed by HPLC after T......-radiolysis in dependence of dose (100-600 Gy) are given for N2O-, air-, oxygen- and argon saturated neutral aqueous solutions. In conditions favoring the OH radical oxidation 4-chlorophenol, 4-methoxyphenol, 5-chloro-2-methoxyphenol and 2-chloro-5-methoxyphenol were determined as final products. In the presence of Ar...

Radiolysis of Fricke solution: initial experiments with the pelletron facility

International Nuclear Information System (INIS)

Sharma, S.B.; Rao, B.S.M.

1994-01-01

Experimental details of heavy ion irradiation of aqueous solutions using the Nuclear Science Centre (NSC) pelletron facility and the initial results from the radiolysis of Fricke solution using oxygen-16 ions are reported. (author). 4 refs., 1 fig

Low-activation lead coolant for advanced small modular NPP

International Nuclear Information System (INIS)

Khorasanov, G.L.; Ivanov, A.P.; Blokhin, A.I.

2001-01-01

The purpose of the paper is in studying perspectives of a new heavy liquid metal coolant for a small fast reactor (FR) concept. To reduce the post irradiation activity of the coolant the using of lead isotope, Pb-206, instead of natural lead, Pb-nat, is offered. In this case the accumulation of such hazardous radionuclides, as Po-210, Bi-208, Bi-207, essentially decreases. The interval of the lead-206 coolant cost which does not exceed 20% of the overall FR cost is estimated. The possibility of lead-206 obtaining for FR needs with the centrifugal separation technique is pointed out. (author)

The electrochemistry of IGSCC mitigation in BWR coolant circuits

Energy Technology Data Exchange (ETDEWEB)

Macdonald, D.D. [Center for Electrochemical Science and Technology, The Pennsylvania State Univ., University Park, PA (United States)

2002-07-01

A brief review is presented of the electrochemical mitigation of IGSCC in water-cooled reactor heat transport circuit structural materials. Electrochemical control and mitigation is possible, because of the existence of a critical potential for IGSCC and by the feasibility of modifying the environment to displace the corrosion potential (ECP) to a value that is more negative than the critical value. However, even in cases where the ECP cannot be displaced sufficiently in the negative direction to become more negative than the critical potential, considerable advantage is accrued, because of the roughly exponential dependence of crack growth rate on potential. The most important parameters in affecting electrochemical control over the ECP and crack growth rate are the kinetic parameters (exchange current densities and Tafel constants) for the redox reactions involving the principal radiolysis products of water (O{sub 2}, H{sub 2}, H{sub 2}O{sub 2}), external solution composition (concentrations of O{sub 2}, H{sub 2}O{sub 2}, and H{sub 2}), flow velocity, and the conductivity of the bulk environment. The kinetic parameters for the redox reactions essentially determine the charge transfer impedance of the steel surface, which is shown to be one of the key parameters in affecting the magnitude of the coupling current and hence the crack growth rate. The exchange current densities, in particular, are amenable to control by catalysis or inhibition, with the result that surface modification techniques are highly effective in controlling and mitigating IGSCC in reactor coolant circuit materials. (authors)

Experimental study on utilization of air-borne jet sound in coolant leak detector

International Nuclear Information System (INIS)

Hayamizu, Y.; Kitahara, T.; Hayashi, T.; Nishimura, M.

1975-10-01

Studies have been undertaken to develop a new coolant leak detection method by the use of a microphone to pick up jet sound generated when pressurized high temperature water is discharged from a pressure boundary into the atmosphere. Leakage was simulated in three shapes, such as two machine-made circular holes and longitudinal and transverse slits in an inlet tube of a blowdown test facility. The measured power level of the jet sound was in agreement with theoretical values calculated from Lighthill's equation. In the study of utilization, this new method has been confirmed as applicable, and to be calculated theoretically for design on 'signal to noise ratio' evaluation. Detection of a small coolant leakage of 1 kg/sec is possible in a recirculation pump room which has large background noise from the pump if a suitable isolation wall, such as hot boxes, is installed between the monitored pipes and the pump. (auth.)

Gamma-radiolysis effects on leaching of nuclear fuel waste forms

International Nuclear Information System (INIS)

Tait, J.C.; Wilkin, D.L.; Hamon, R.F.

1986-06-01

Gamma-radiolysis experiments have been conducted on aqueous systems representative of those that might be found in a granite rock disposal vault for immobilized nuclear fuel recycle waste. Sealed capsules containing an air or an oxygen-free atmosphere, synthetic granite or chloride groundwaters, and components of the disposal system (granite, clay, metal containers and glass or glass-ceramic waste form) were irradiated by an external gamma field. Analysis of the gas phase showed the presence of H 2 gas in all capsules. Capsules containing graphite and air showed oxygen depletion. This depletion of O 2 is attributed to radiolytic reactions with iron species leached from the granite. Systems containing bentonite clay showed the production of CO 2 . A computer program, MAKSIMA-CHEMIST, was used to qualitatively predict the observed gas-phase composition by modelling the kinetics of the aqueous radiolysis reactions

Radiolysis of dodecane--tributylphosphate and nitrous oxide solutions

International Nuclear Information System (INIS)

Razvi, J.

1978-01-01

The chemical effects of 60 Co gamma irradiation on the nuclear fuel reprocessing solvents tributylphosphate (TBP) and dodecane were studied. Nitrous oxide, with concentrations in the range 20 mM to 140 mM, was used as the standard for competition kinetics. Solutions of TBP (with electron fractions of 0.025, 0.05, 0.1 and 0.3) in dodecane were irradiated. Primary gaseous products (non-condensible at 77K) in the radiolysis were nitrogen and hydrogen. Liquid products observed were the dimer, dodecanone, dodecanol, and fragmentation products C 5 -C 11 and C 17 -C 20 . Acid products from TBP were dibutylphosphate (DBP) and monobutylphosphate (MBP). All yields were determined both as a function of TBP and nitrous oxide concentrations. Kinetic analysis of nitrogen yields from dodecane--N 2 O radiolysis gave, G(total scavengable primary species) = 6.7 molecules/100 eV. Yields of dodecane liquid products could not be analyzed quantitatively due to the complex spectrum of products. In dodecane--N 2 O solutions, the dimer showed insignificant changes in yields and product distributions, indicating formation of additional dodecyl radicals in the presence of nitrous oxide. In dodecane--TBP mixtures, dimer yields reduced significantly as did the products from carbon--carbon bond cleavage. The addition of nitrous oxide to the binary mixture caused the dimer yield to increase, confirming formation of C 12 H 25 radicals by nitrous oxide reactions

Pulse radiolysis study of the reactions of catechins with nitrogen dioxide

International Nuclear Information System (INIS)

Gebicki, Jerzy L.; Meisner, Piotr; Stawowska, Katarzyna; Gebicka, Lidia

2012-01-01

Nitrogen dioxide ( • NO 2 ), one of the oxidizing radicals formed in vivo is suspected to play a role in various pathophysiological processes. The reactions of • NO 2 with dietary catechins, the group of flavonoids present in high amounts in green tea and red wine, have been investigated by pulse radiolysis method. The kinetics of the reaction of • NO 2 with gallic acid have been also studied for comparison. The spectra of transient intermediates are presented. The rate constants of the reaction of • NO 2 with catechin, epigallocatechin, epigallocatechin gallate and gallic acid determined by the competition method with 2,2’-azinobis-(3-ethylbenzthiazoline-6-sulfonate) at pH 7.0 and room temperature have been found to be 0.9, 1.0, 2.3 and 0.5×10 8 M −1 s −1 , respectively. The values for catechins are among the highest reported for the reactions of • NO 2 with non-radical compounds. - Highlight: ► Reaction kinetics of catechins with · NO 2 is studied by the competition method. ► Catechins are excellent · NO 2 scavengers. ► Epigallocatechin gallate is the best · NO 2 scavenger among investigated catechins.

Selecting ethanol as an ideal organic solvent probe in radiation chemistry γ-radiolysis of acetone-ethanol system and acetophenone-ethanol system

International Nuclear Information System (INIS)

Jin Haofang; Wu Jilan; Fang Xingwang; Zhang Xujia

1995-01-01

Radiolysis of acetone-ethanol solution and acetophenone-ethanol solution has been studied in this work. The dependences of G values of the final γ radiolysis products such as H 2 . 2,3-butanediol and acetaldehyde on additive concentration in liquid ethanol have been obtained. There are two kinds of new final products, isopropanol and 2-methyl-2,3-butanediol are detected in irradiated acetone-ethanol solution. As for acetophenone-ethanol system, more new final products are found. In addition, experiments of pulse radiolysis upon acetophenone-ethanol solution have also been performed. The absorption spectrum with λ max at 315nm and 440nm is observed, which is assigned to ketyl radical ion C 6 H 5 (CH 3 )CO - . And the reaction mechanism of the two systems is proposed respectively with a moderate success. (author)

Development of hydrogen oxidizing bacteria using hydrogen from radiolysis or metal corrosion

International Nuclear Information System (INIS)

Libert, M.F.; Sellier, R.; Marty, V.; Camaro, S.

2000-01-01

The effect of many parameters need to be studied to characterize the long term behavior of nuclear waste in a deep repository. These parameters concern the chemical effects, radiolytic effects, mechanical properties, water composition, and microbiological activity. To evaluate microbial activity in such an environment, work was focused on an inventory of key nutrients (C, H, 0, N, P, S) and energy sources required for bacterial growth. The production of hydrogen in the nuclear waste environment leads to the growth of hydrogen oxidizing bacteria, which modify the gas production balance. A deep repository containing bituminized waste drums implies several sources of hydrogen: - water radiolysis; -corrosion of metal containers; - radiolysis of the embedding matrix (bitumen). Two deep geological disposal conditions leading to H 2 production in a bituminized nuclear waste environment were simulated in the present study: - H 2 production by iron corrosion under anaerobic conditions was simulated by adding 10% of H 2 in the atmosphere; - H 2 production by radiolysis of bitumen matrix was approached by subjecting this material to external gamma irradiation with a dose rate near real conditions (6 Gy/h). The presence of dissolved H 2 in water allows the growth of hydrogen oxidizing bacteria leading to: - CO 2 and N 2 production; - H 2 consumption; - lower NO 3 - concentration caused by reduction to nitrogen. In the first case, hydrogen consumption is limited by the NO 3 - release rate from the bitumen matrix. In the second case, however, under gamma radiation at a low dose rate, hydrogen production is weak, and the hydrogen is completely consumed by microorganisms. Knowledge about these hydrogen oxidizing bacteria is just beginning to emerge. Heterotrophic denitrifying bacteria adapt well to hydrogen metabolism (autotrophic metabolism) by oxidizing H 2 instead of hydrocarbons. (authors)

Radiolysis of uracil in oxygenated aqueous solutions. A study by product analysis and pulse radiolysis. [Gamma radiation

Energy Technology Data Exchange (ETDEWEB)

Schuchnmann, M N; Sonntag, C von [Max-Planck-Institut fuer Kohlenforschung, Muelheim an der Ruhr (Germany, F.R.). Inst. fuer Strahlenchemie

1983-10-01

Hydroxyl radicals are generated by the radiolysis of N/sub 2/O-O/sub 2/ (4:1 v/v)-saturated aqueous solutions of uracil. They add to the 5,6-double bond of the substrate. These radicals are converted by oxygen into the corresponding peroxyl radicals (I) and (II), respectively. Peroxyl radical (I) undergoes a base-induced O/sub 2//sup -/ elimination. As an intermediate 5-hydroxyisopyrimidine is formed which rearranges into isobarbituric acid and adds water forming 5,6-dihydro-5,6-dihydroxyuracil. Competing with this base-induced reaction of radical (I) there is a bimolecular decay of radicals (I) and (II). These processes become predominant at low pH. For this reason a strong pH dependence of G (products) is observed. The major products are (G values at pH 3 and 10 in parentheses) 5,6-dihydroxy-5,6-dihydrouracil (1.1; 2.4), isobarbituric acid (0; 1.2), N-formyl-5-hydroxyhydantoin (1.6; 0.2), 5-hydroxybarbituric acid (0.9; 0.2). 5-Hydroxybarbituric acid is formed in its keto form. Its deprotonation has been followed by pulse conductometry. Details of the reaction mechanism, e.g. the involvement of oxyl radicals in the bimolecular decay of (I) and (II), are discussed.

The effect of temperature on radiolysis of iodide ion diluted aqueous solutions

Energy Technology Data Exchange (ETDEWEB)

Gorbovitskaya, T; Tiliks, J [Latvia Univ., Lab. of Radiation Chemistry, Riga (Latvia)

1996-12-01

To investigate the radiolysis of iodine containing aqueous solutions a flow type facility (ITF) has a possibility to irradiate aqueous solutions in the steel vessel with {sup 60}Co {gamma}-rays and continuously (on line) to analyze the products of radiolysis both in liquid and in gaseous phases. By means of ITF the formation of I{sub ox} (I{sub 2} + I{sub 3}{sup -} + HOI), IO{sub 3}{sup -}, H{sub 2}O{sub 2} was studied in 10{sup -5} - 10{sup -3} mol/dm{sup 3} CsI aqueous solutions by their radiolysis at dose rate 4.5 kGv/h for six hours in region of temperatures from 313 to 404 K. Some experiments in glass ampoules were also performed. The steady-state concentrations of I{sub ox} and IO{sub 3}{sup -} decreased with increasing temperature as linear function of inverted temperature. The effect decreased with decreasing concentration of iodide ion. As the result, at high temperatures (T{>=}380 K) the steady-state concentration of I{sub ox} does not depend essentially on the iodide ion initial concentration. Molecular iodine (I{sub 2}) released from the solution was the main radiolysis product in gaseous phase. Its steady-state concentration increased with increasing temperature because of iodine solubility in the water and decreased at the same time because the radiolytic iodine concentrations decreased. Therefore the most volatility of irradiated 10{sup -3} and 10{sup -4}M CsI solutions was observed at the temperature about 350 K. The volatility of 10{sup -5}M solutions gradually decreased with increasing temperature. The experimental data were explained on the base of the hypothesis that the reaction between I{sub 2} and radiolytic H{sub 2}O{sub 2} was the limit one determining the temperature dependence of I{sub ox} and IO{sub 3}{sup -}steady-state concentrations. Its activation energy was estimated to be 27,5 kcal.mol{sup -1}. The temperature dependence for reaction (IO{sup -} + H{sub 2}O{sub 2}) was also estimated. (author) 8 figs., 1 tab., 17 refs.

Pulse radiolysis studies of liquid heavy water at temperatures up to 250 degrees C

International Nuclear Information System (INIS)

Stuart, C.R.; Ouellette, D.C.; Elliot, A.J.

2002-09-01

This report documents the rate constants and associated activation energies for the reactions of the primary radical species, e aq - , ·OD and ·D, which are formed during the radiolysis of heavy water within the temperature range 20 to 250 o C. These heavy-water data have been compared with the corresponding information for light water. These kinetic data form part of the database that is required to model the aqueous radiation chemistry that occurs within the core of the heavy water cooled and moderated CANDU reactor. (author)

Pulse radiolysis studies of liquid heavy water at temperatures up to 250 degrees C

Energy Technology Data Exchange (ETDEWEB)

Stuart, C.R.; Ouellette, D.C.; Elliot, A.J

2002-09-01

This report documents the rate constants and associated activation energies for the reactions of the primary radical species, e{sub aq}{sup -}, {center_dot}OD and {center_dot}D, which are formed during the radiolysis of heavy water within the temperature range 20 to 250 {sup o}C. These heavy-water data have been compared with the corresponding information for light water. These kinetic data form part of the database that is required to model the aqueous radiation chemistry that occurs within the core of the heavy water cooled and moderated CANDU reactor. (author)

Reactor coolant pump transportation incident

International Nuclear Information System (INIS)

Noce, D.

1992-01-01

This paper reports on an incident, which occurred on August 27, 1991, in which a Reactor Coolant Pump motor en route from Surry Power Station to Westinghouse repair facilities struck the overpass at the junction of Interstate 64 and Jefferson Avenue in Newport News, Virginia. The transport container that housed the reactor coolant pump motor failed to clear the overpass. The force of the impact dislodged the container and motor from the truck bed, and it landed on the acceleration land and road shoulder. Upon impact, the container broke open and exposed the reactor coolant pump motor. Incidental radioactively contaminated water that remained in the motor coolers drained onto the road, contaminating the aggregate as well as the underlying gravel

Analysis of final products from the liquid alkanes radiolysis at low dose, low temperature and high dose rate

International Nuclear Information System (INIS)

Tilquin, B.; Doncker, J. de.

1991-01-01

Yields of final products (dimers) from the radiolysis of n-hexane and 2,3-dimethylbutane are studied by capillary chromatographic techniques for trace analysis. Reaction of intermediates with the products, the alkane molecules or impurities, is reduced by using low dose (1 kGy), low temperature (195 K) and high dose rate (LINAC). Temperature is the most important experiment variable; by reducing the temperature, reactions with significant activation energies do not compete with radical-radical termination reactions. Products from LINAC radiolysis provide information about active species (reactive fragment, allylic radical...) which deserve a more detailed examination by direct methods [fr

Pulse radiolysis based on a femtosecond electron beam and a femtosecond laser light with double-pulse injection technique

International Nuclear Information System (INIS)

Yang Jinfeng; Kondoh, Takafumi; Kozawa, Takahiro; Yoshida, Youichi; Tagawa, Seiichi

2006-01-01

A new pulse radiolysis system based on a femtosecond electron beam and a femtosecond laser light with oblique double-pulse injection was developed for studying ultrafast chemical kinetics and primary processes of radiation chemistry. The time resolution of 5.2 ps was obtained by measuring transient absorption kinetics of hydrated electrons in water. The optical density of hydrated electrons was measured as a function of the electron charge. The data indicate that the double-laser-pulse injection technique was a powerful tool for observing the transient absorptions with a good signal to noise ratio in pulse radiolysis

Interfacial radiolysis effects in tank waste speciation. 1997 annual progress report

International Nuclear Information System (INIS)

Orlando, T.M.

1997-01-01

'The purpose of this program is to deliver pertinent, fundamental information that can be used to make technically defensible decisions on safety issues and processing strategies associated with mixed chemical and radioactive waste cleanup. In particular, an understanding of radiolysis in mixed-phase systems typical of U. Department of Energy (DOE) heterogeneous, radioactive/chemical wastes will be established. This is an important scientific concern with respect to understanding tank waste chemistry issues; it has received relatively little attention. The importance of understanding solid-state radiolysis, secondary electron interactions, charge-transfer dynamics, and the general effect of heterogeneous solids (interface and particulate surface chemistry) on tank waste radiation processes will be demonstrated. In particular, the author will investigate (i) the role of solid-state and interfacial radiolysis in the generation of gases, (ii) the mechanisms of organic compound degradation, (iii) scientific issues underlying safe interim storage, and (iv) the effects of colloid surface-chemical properties on waste chemistry. Controlled radiolysis studies of NaNO 3 solids and SiO 2 particles were carried out using pulsed, low- (5--150 eV) and high- (3 MeV) energy electron-beams at Pacific Northwest National Laboratory (PNNL) and at Argonne National Laboratory (ANL), respectively. The pulsed, low-energy electron beams probe the inelastic scattering and secondary cascading effects produced by high-energy beta and gamma particles. Pulsed radiolysis allows time-resolved measurements of the high-energy processes induced by these particles. Using low-energy (10--75 eV) electron-beam irradiation of nominally dry NaNO 3 solution-grown and melt-grown single crystals, they observed H + , Na + , O + , NO + , NO, NO 2 , O 2 , and O( 3 P) desorption signals. The threshold measurements and yields indicate that the degradation proceeds mainly via destruction of the nitrate moiety. The

Design of automotive engine coolant hoses

Directory of Open Access Journals (Sweden)

Hrishikesh D BACHCHHAV

2018-03-01

Full Text Available In this paper, we are present the performance of engine coolant hoses (radiator hoses used in passenger cars by checking various physical behaviours such as hose leakage, hose burst, hose collapse or any mechanical damage as studied-thru design guidelines, CFD analysis and product validation testing and also check pressure drop of the hoses when engine will be running. The design term is more likely used for technical part modelling using CAD tool. Later on, we will focus on the transformation of the part design to process design. The process design term is more likely used for "tooling design" for manufacturing of the product using CAD Tool. Then inlet hose carries coolant from engine to radiator inlet tank, then coolant circulated in radiator and passed through radiator outlet tank to water pump of engine with the help of outlet hose. After that …nding any leakage, Burst, damage or collapse of hose and pressure drop of the hose with the help of design checklist, CFD Analysis and product validation testing.

Evaluation of filtration and distillation methods for recycling automotive coolant

International Nuclear Information System (INIS)

Randall, P.M.; Gavaskar, A.R.

1992-01-01

Government regulations and high waste disposal cost of spent automotive coolant have driven the vehicle maintenance industry to explore on-site recycling. The USEPA in cooperation with the New Jersey Department of Environmental Protection (NJDEP) and the New Jersey Department of Transportation (NJDOT) evaluated two commercially available technologies that have potential for reducing the volume of spent automotive coolant. The objective of this study was to evaluate the quality of the recycled coolant, the pollution prevention potential, and the economic feasibility of the technologies

Primary coolant circuits in FBR type reactors

International Nuclear Information System (INIS)

Kutani, Masushiro.

1985-01-01

Purpose: To eliminate the requirement of a pump for the forcive circulation of primary coolants and avoid the manufacturing difficulty of equipments. Constitution: In primary coolant circuits of an LMFBR type reactor having a recycling path forming a closed loop between a reactor core and a heat exchanger, coolants recycled through the recycling path are made of a magnetic fluid comprising liquid sodium incorporated with fine magnetic powder, and an electromagnet is disposed to the downstream of the heat exchanger. In the above-mentioned structure, since the magnetic fluid as the primary coolants losses its magnetic property when heated in the reactor core but recovers the property at a lower temperature after the completion of the heat exchange, the magnetic fluid can forcively be flown through the recycling path under the effect of the electromagnet disposed to the down stream of the heat exchanger to thereby forcively recycle the primary coolants. (Kawakami, Y.)

Numerical study on coolant flow distribution at the core inlet for an integral pressurized water reactor

Energy Technology Data Exchange (ETDEWEB)

Sun, Lin; Peng, Min Jun; Xia, Genglei; Lv, Xing; Li, Ren [Fundamental Science on Nuclear Safety and Simulation Technology Laboratory, Harbin Engineering University, Harbin (China)

2017-02-15

When an integral pressurized water reactor is operated under low power conditions, once-through steam generator group operation strategy is applied. However, group operation strategy will cause nonuniform coolant flow distribution at the core inlet and lower plenum. To help coolant flow mix more uniformly, a flow mixing chamber (FMC) has been designed. In this paper, computational fluid dynamics methods have been used to investigate the coolant distribution by the effect of FMC. Velocity and temperature characteristics under different low power conditions and optimized FMC configuration have been analyzed. The results illustrate that the FMC can help improve the nonuniform coolant temperature distribution at the core inlet effectively; at the same time, the FMC will induce more resistance in the downcomer and lower plenum.

Theoretical study on loss of coolant accident of a research reactor

International Nuclear Information System (INIS)

Lee, Kwon-Yeong; Kim, Wan-Soo

2016-01-01

Highlights: • A theoretical model of siphon breaking phenomena was developed. • A general formula using Chisholm coefficient B was proposed. • The safety requirements regarding a loss of coolant accident of research reactors could be found out. - Abstract: Under the design conditions of a research reactor, the siphon phenomenon induced by pipe rupture can cause continuous efflux of water. In order to prevent water efflux, an additional facility is necessary. A siphon breaker is a type of safety facility that can resist the loss of coolant effectively. However, analysis of siphon breaking is complex since it comprises two-phase flow and there are many inputs to be considered. For this reason, we analyzed the experimental results to develop a theoretical model of siphon breaking phenomena. Developed model is based on fluid mechanics and Chisholm model. From Bernoulli’s equation, the velocity and quantity as well as undershooting height, water level, pressure, friction coefficient, and factors related to the two-phase flow could be calculated. The Chisholm model, which is able to analyze the two-phase flow, can predict the results in a manner similar to those obtained from a real-scale experiment, and a general formula using Chisholm coefficient B was proposed in this study. Also, we verified the theoretical model and concluded that it is possible to analyze the siphon breaking. Moreover, the design conditions that can satisfy the safety requirements regarding a loss of coolant accident of research reactors could be found out by using the theoretical model. In conclusion, we propose the theoretical model which can analyze the siphon breaking as real, and it is helpful not only to analyze but also to design the siphon breaker.

Novel system for pulse radiolysis with multi-angle light scattering detection (PR-MALLS) - concept, construction and first tests

Science.gov (United States)

Kadlubowski, S.; Sawicki, P.; Sowinski, S.; Rokita, B.; Bures, K. D.; Rosiak, J. M.; Ulanski, P.

2018-01-01

Time-resolved pulse radiolysis, utilizing short pulses of high-energy electrons from accelerators, is an effective method for rapidly generating free radicals and other transient species in solution. Combined with fast time-resolved spectroscopic detection (typically in the ultraviolet/visible/near-infrared), it is invaluable for monitoring the reactivity of species subjected to radiolysis on timescales ranging from picoseconds to seconds. When used for polymer solutions, pulse radiolysis can be coupled with light-scattering detection, creating a powerful tool for kinetic and mechanistic analysis of processes like degradation or cross-linking of macromolecules. Changes in the light scattering intensity (LSI) of polymer solutions are indicative of alterations in the molecular weight and/or in the radius of gyration, i.e., the dimensions and shape of the macromolecules. In addition to other detection methods, LSI technique provides a convenient tool to study radiation-induced alterations in macromolecules as a function of time after the pulse. Pulse radiolysis systems employing this detection mode have been so far constructed to follow light scattered at a single angle (typically the right angle) to the incident light beam. Here we present an advanced pulse radiolysis & multi-angle light-scattering-intensity system (PR-MALLS) that has been built at IARC and is currently in the phase of optimization and testing. Idea of its design and operation is described and preliminary results for radiation-induced degradation of pullulan as well as polymerization and crosslinking of poly(ethylene glycol) diacrylate are presented. Implementation of the proposed system provides a novel research tool, which is expected to contribute to the expansion of knowledge on free-radical reactions in monomer- and polymer solutions, by delivering precise kinetic data on changes in molecular weight and size, and thus allowing to formulate or verify reaction mechanisms. The proposed method is

Effect of spacer grid mixing vanes on coolant outlet temperature distribution

Energy Technology Data Exchange (ETDEWEB)

Raemae, Tommi; Lahtinen, Tuukka; Brandt, Tellervo; Toppila, Timo [Fortum Power and Heat, Fortum (Finland). Nuclear Competence Center

2012-08-15

In Loviisa VVER-440-type NPP the coolant outlet temperature of the hot subchannel is constantly monitored during the operation. According to the authority requirement the maximum subchannel outlet temperature must not exceed the saturation temperature. Coolant temperature distribution inside the fuel assembly is affected by the efficiency of the coolant mixing. In order to enhance the coolant mixing the fuel manufacturer is introducing the additional mixing vanes on the fuel bundle spacer grids. In the paper the effect of the different mixing vane modifications is studied with computational fluid dynamics (CFD) simulation. Goal of the modelling is to find vane modifications with which sufficient mixing is reached with acceptable increase in the spacer grid pressure loss. The results of the studies are discussed in the paper. (orig.)

Biomarkers on Europa: Unique signatures produced by radiolysis?

Science.gov (United States)

Carlson, R. W.; Hand, K. P.

A promising habitat for life is Jupiter's moon Europa, with its likely ocean under a young, active surface. Europa orbits in the heart of Jupiter's powerful magnetosphere and suffers intense energetic particle bombardment, producing both good and bad aspects for astrobiology at Europa. Ionizing radiation can produce oxidants that could support a radiation-driven ecology as proposed by Chyba. On the other hand, biomolecular evidence for oceanic life that may be emplaced on the surface is rapidly altered by radiation, perhaps complicating astrobiological searches for evidence of life. We are studying the radiolytic degradation of molecular biomarkers in ice at Europa temperatures by studying both simple organics and more complex biomolecules, including microorganisms. High energy (1-100 keV) electron irradiation is employed and the products are analyzed using infrared spectroscopy, thermal desorption mass spectroscopy, and laser desorption/ionization mass spectroscopy. Hydrocarbon radiolysis yields carbon dioxide and methane which can escape the system and results in the net loss of carbon. Aliphatic molecules with C=O bonds are formed and thought to be mainly polymethylene oxides. When heated, they polymerize to form brown, high-molecular-weight refractory residues with linear, spherical, and ring- shaped macrostructures, typically many tens of micrometers in size. Laser desorption mass spectra of the residues are not overly complex and are different for each initial species. Radiolysis of microorganisms shows the destruction of amine, amide, methyl, and methylene groups, and production of carbon dioxide, carbon monoxide, nitriles, and isocyanates. Mass spectra of irradiated B. pumilus spores are different and surprisingly less complex than those of unirradiated spores. It is possible that unique, diagnostic biosignatures may exist in mass spectra of irradiated microorganisms.

Upper internals of PWR with coolant flow separator

International Nuclear Information System (INIS)

Chevereau, G.; Heuze, A.

1989-01-01

The upper internals for a PWR has a collecting volume for the coolant merging from the core and an apparatus for separating the flow of coolant. This apparatus has a guide for the control rods, a lower plate perforated to allow the coolant through from the core, an upper plate also perforated to allow the coolant through to the collecting volume and a peripheral binding ring joining the two plates. Each guide comprises an envelope without holes and joined perceptibly tight to the plates [fr

A pulse radiolysis based singlet oxygen luminescence facility

International Nuclear Information System (INIS)

Gorman, A.A.; Hamblett, I.; Land, E.J.

1989-01-01

In this paper the authors report the first successful time-resolved detection of singlet oxygen, O 2 ( 1 Δ g ), luminescence using the pulse radiolysis technique. The use of this technique (a) to produce high concentrations of solute (S) triplet states in aerated benzene (B) via a combination of channels 1-4 and (b) to subsequently form O 2 ( 1 Δ g ) via channel 5 has already been described. The method complements direct pulsed laser excitation of S in that formation of 3 S*, and therefore of O 2 ( 1 Δ g ), is still efficient in those instances where intersystem crossing (channel 4) is unimportant. In the latter situation a laser-based experiment would require an additional light-absorbing sensitizer which could subsequently transfer triplet energy to high concentrations of S. Such experiments, certainly of a quantitative nature, are usually doomed to failure because of competitive light absorption problems. No such problems exist with pulse radiolysis, and the high available triplet energy of 3 B* (84 kcal mol -1 ) ensures that virtually any solute of interest, in the O 2 ( 1 Δ g ) context, will be efficiently promoted to its triplet state

Pulse radiolysis studies of mangiferin: A C-glycosyl xanthone isolated from Mangifera indica

Energy Technology Data Exchange (ETDEWEB)

Mishra, B. [Radiation Chemistry and Chemical Dynamics Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Priyadarsini, K.Indira [Radiation Chemistry and Chemical Dynamics Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India)]. E-mail: kindira@apsara.barc.ernet.in; Sudheerkumar, M. [College of Pharmaceutical Sciences, Kasturba Medical College, Manipal 576119 (India); Unnikrishhnan, M.K. [College of Pharmaceutical Sciences, Kasturba Medical College, Manipal 576119 (India); Mohan, H. [Radiation Chemistry and Chemical Dynamics Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India)

2006-01-15

Pulse radiolysis technique has been employed to study the reaction of different oxidizing and reducing radicals with mangiferin. The reaction of {sup {center_dot}}OH radical showed the formation of transient species absorbing in 380-390 and 470-480 nm region. The reaction with specific one-electron oxidants (N{sub 3} {sup {center_dot}}, CCl{sub 3}O{sub 2} {sup {center_dot}}) also showed the formation of similar transient absorption bands and is assigned to phenoxyl radicals. The pK {sub a} values of the transient species have been determined to be 6.3 and 11.9. One-electron oxidation potential of mangiferin at pH 9 has been found to be 0.62 V vs. NHE. The reaction of e{sub aq} {sup -} showed the formation of transient species with {lambda} {sub max} at 340 nm, which is assigned to the ketyl anion radical formed on addition of e{sub aq} {sup -} at carbonyl site. Reactions of one-electron oxidised mangiferin radicals with ascorbic acid have also been studied.

Pulse radiolysis of pyridine and methylpyridines in aqueous solutions

DEFF Research Database (Denmark)

Solar, S.; Getoff, N.; Sehested, K.

1993-01-01

The radicals formed from pyridine, 3-methylpyridine, 3,5-dimethylpyridine, 2,6-dimethylpyridine and 2,4,6-trimethylpyridine by attack of H, e(aq)-, OH and O.- in aqueous solutions were investigated by pulse radiolysis in the pH-range 1-13.8. The UV-vis. absorption spectra as well as the formation...

Pulse radiolysis study of aqueous cyanamide solutions

International Nuclear Information System (INIS)

Draganic, I.G.; Draganic, Z.D.; Sehested, K.

1978-01-01

The radiolysis of oxygen-free, aqueous solutions of cyanamide was studied by fast kinetic spectrophotometry. Computer simulation of the reaction mechanisms was used to evaluate the experimental data. Four different species are identified: (1) the radical anion (NH 2 CN) - absorbing light in the UV with lambda/sub max/ 240 = 1500 M -1 cm -1 ; the disappearance is a second-order process with 2k = 1.3 x 10 9 M -1 s -1 ; (2) the hydrogen adduct, NH 2 C(H) double bond N (or NH 2 C double bond NH), with lambda/sub max/ 300 nm and epsilon 300 = 150 M -1 cm -1 decaying by second-order kinetics with 2k = 3.1 x 10 9 M -1 s -1 ; (3) the hydroxyl radical preferentially adds to the cyano group, NH 2 C(OH) double bond N (or NH 2 C double bond NOH). This species rearranges in the submicrosecond scale to NH 2 C ( double bond O) NH (lambda/sub max/ 325 nm and epsilon/sub 325 = 1900 M -1 cm -1 ) and disappears by a second-order process with 2k = 6.3 x 10 9 M -1 s -1 . (4) It is estimated that about 10% of OH radicals attack the substituent group and by H abstraction produce the NHCN radical (lambda/sub max/ 370 nm and epsilon 370 = 1800 M -1 cm -1 ); it disappears by a pseudo-first-order process attributed to a hydrolysis reaction. At increasing acidities, protonation of this radical takes place, NHCN + H + → + NH 2 CN; the protonated form decays faster and absorbs more strongly. In a cyanamide solution containing S 2 O 8 2- , the SO - 4 . radicals react with cyanamide, k = 1 x 10 8 M -1 s -1 , producing + NH 2 CN radicals. The dependence of the optical density at 325 nm on the dose rate and solute concentration are quantitatively consistent with the assumption that the OH radicals react with the NH 2 C(=O)NH species with k = 4 x 10 9 M -1 s -1

Computer modeling of inhibition of α-radiolysis of water by H2 addition (NPC 2012 conference)

International Nuclear Information System (INIS)

Lertnaisat, Phantira; Katsumura, Yosuke; Mukai, Satoru; Umehara, Ryuji; Shimizu, Yuichi; Suzuki, Masaru

2012-09-01

It is known that α-radiolysis of water produces H 2 gas continuously. The addition of H 2 to water inhibits the water decomposition; H 2 evolution. In order to suppress the water decomposition, 25 cc H 2 STP/kg-H 2 O is added to the coolant water in PWR. However, the exact inhibition mechanism is still not made clear yet. In this project, the chemical kinetic simulation program, so called FASCIMILE, was used to reproduce the suppression of α-radiolysis of water by H 2 addition. By using three important factors; the decomposition (G-value), the reaction set and rate constants, and the dose rate, it is found that without hydrogen addition, the simulation shows the almost linear increase of molecular products; H 2 , H 2 O 2 , and O 2 . Nevertheless, as the additional hydrogen is added to the system, this behaviour of linear increase is shifted to longer time period. And up to certain concentration, the linear increase behaviour is completely suppressed and the molecular products reach the steady state condition at early time period and much lower concentration. The minimum concentration of H 2 which could completely suppress the decomposition of water is called Critical Hydrogen Concentration (CHC) and it is dose rate dependent value. The CHC is found to be dependent on the reaction set and rate constants. The simulation results show that the CHC at room temperature and dose rate of 1 kGy/s of the simulation done by using reaction set and rate constants obtained from Ershov et al. and AECL report 2009 are 165μM and 146μM, respectively. From the change of the behaviour of molecular products after reaching the CHC, the possible mechanism is proposed. First, the OH radical are formed via the reaction of H + H 2 O 2 → OH + H 2 O and e - aq + H 2 O 2 → OH+OH - . Then OH, which normally will react with H 2 O 2 to produced HO 2 , will react with the additional H 2 , which produce H to continue the chain reaction. The relation of chain reaction to the suppression of

Simulation of steam explosion in stratified melt-coolant configuration

International Nuclear Information System (INIS)

Leskovar, Matjaž; Centrih, Vasilij; Uršič, Mitja

2016-01-01

Highlights: • Strong steam explosions may develop spontaneously in stratified configurations. • Considerable melt-coolant premixed layer formed in subcooled water with hot melts. • Analysis with MC3D code provided insight into stratified steam explosion phenomenon. • Up to 25% of poured melt was mixed with water and available for steam explosion. • Better instrumented experiments needed to determine dominant mixing process. - Abstract: A steam explosion is an energetic fuel coolant interaction process, which may occur during a severe reactor accident when the molten core comes into contact with the coolant water. In nuclear reactor safety analyses steam explosions are primarily considered in melt jet-coolant pool configurations where sufficiently deep coolant pool conditions provide complete jet breakup and efficient premixture formation. Stratified melt-coolant configurations, i.e. a molten melt layer below a coolant layer, were up to now believed as being unable to generate strong explosive interactions. Based on the hypothesis that there are no interfacial instabilities in a stratified configuration it was assumed that the amount of melt in the premixture is insufficient to produce strong explosions. However, the recently performed experiments in the PULiMS and SES (KTH, Sweden) facilities with oxidic corium simulants revealed that strong steam explosions may develop spontaneously also in stratified melt-coolant configurations, where with high temperature melts and subcooled water conditions a considerable melt-coolant premixed layer is formed. In the article, the performed study of steam explosions in a stratified melt-coolant configuration in PULiMS like conditions is presented. The goal of this analytical work is to supplement the experimental activities within the PULiMS research program by addressing the key questions, especially regarding the explosivity of the formed premixed layer and the mechanisms responsible for the melt-water mixing. To

Radiolysis products and sensory properties of electron-beam-irradiated high-barrier food-packaging films containing a buried layer of recycled low-density polyethylene.

Science.gov (United States)

Chytiri, S D; Badeka, A V; Riganakos, K A; Kontominas, M G

2010-04-01

The aim was to study the effect of electron-beam irradiation on the production of radiolysis products and sensory changes in experimental high-barrier packaging films composed of polyamide (PA), ethylene-vinyl alcohol (EVOH) and low-density polyethylene (LDPE). Films contained a middle buried layer of recycled LDPE, while films containing 100% virgin LDPE as the middle buried layer were taken as controls. Irradiation doses ranged between zero and 60 kGy. Generally, a large number of radiolysis products were produced during electron-beam irradiation, even at the lower absorbed doses of 5 and 10 kGy (approved doses for food 'cold pasteurization'). The quantity of radiolysis products increased with irradiation dose. There were no significant differences in radiolysis products identified between samples containing a recycled layer of LDPE and those containing virgin LDPE (all absorbed doses), indicating the 'functional barrier' properties of external virgin polymer layers. Sensory properties (mainly taste) of potable water were affected after contact with irradiated as low as 5 kGy packaging films. This effect increased with increasing irradiation dose.

Coolant processing device for nuclear reactor

International Nuclear Information System (INIS)

Kizawa, Hideo; Funakoshi, Toshio; Izumoji, Yoshiaki

1981-01-01

Purpose: To reduce an entire facility cost by concentrating and isolating tritium accumulated in coolants, removing the tritium out of the system, and returning hydrogen gas generated at a reactor accident to a recombiner in a closed loop by the switching of a valve. Constitution: Coolant from a reactor cooling system processed by a chemical volume control system facility (CVCS) and coolant drain from various devices processed by a liquid waste disposing system facility (LWDS) are fed to a tritium isolating facility, in which they are isolated into concentrated tritium water and dilute tritium water. The concentrated tritium water is removed out of the system and stored. The dilute tritium water is reused as supply water for coolant. If an accident occurs to cause hydrogen to be generated, a closed loop is formed between the containment vessel and the recombiner, the hydrogen is recombined with oxygen in the air of the closed loop to be thus returned to water. (Kamimura, M.)

Selection of nuclear reactor coolant materials

International Nuclear Information System (INIS)

Shi Lisheng; Wang Bairong

2012-01-01

Nuclear material is nuclear material or materials used in nuclear industry, the general term, it is the material basis for the construction of nuclear power, but also a leader in nuclear energy development, the two interdependent and mutually reinforcing. At the same time, nuclear materials research, development and application of the depth and breadth of science and technology reflects a nation and the level of the nuclear power industry. Coolant also known as heat-carrier agent, is an important part of the heart nuclear reactor, its role is to secure as much as possible to the economic output in the form fission energy to heat the reactor to be used: the same time cooling the core, is controlled by the various structural components allowable temperature. This paper described the definition of nuclear reactor coolant and characteristics, and then addressed the requirements of the coolant material, and finally were introduced several useful properties of the coolant and chemical control. (authors)

Fatigue management considering LWR coolant environments

International Nuclear Information System (INIS)

Park, Heung Bae; Jin, Tae eun

2000-01-01

Design fatigue curve for structural material in the ASME Boiler and Pressure Vessel Code do not explicitly address the effects of reactor coolant environments on fatigue life. Environmentally assisted cracking (EAC) of low-alloy steels in light water reactor (LWR) coolant environments has been a concern ever since the early 1970's. And, recent fatigue test data indicate a significant decrease in fatigue lives of carbon steels, low-alloy steels and austenitic stainless steels in LWR coolant environments. For these reasons, fatigue of major components has been identified as a technical issue remaining to be resolved for life management and license renewal of nuclear power plants. In the present paper, results of recent investigations by many organizations are reviewed to provide technical justification to support the development of utility approach regarding the management of fatigue considering LWR coolant environments for the purpose of life management and license renewal of nuclear power plants. (author)

Kinetics of radiolysis of irradiated ligno celluloses into soluble products in water and rumen liquid

International Nuclear Information System (INIS)

Tukenmez, I.; Bakioglu, A.T.; Ersen, M.S.

1997-01-01

In order to increase the low bio hydrolysis of ligno celluloses in biotechnological and biological processes where these materials are used as raw materials and ruminant feed, the substrates were pretreated with irradiation to induce radiolytic depolymerisation and then kinetics of their radiolysis into soluble products in water and rumen liquid were analyzed. Wheat straw used as a representative lignocellulose substrate was irradiated at 0-2.5 MGy doses at 20''o''C with an optimum equilibrium humidity of 6.6% in Cs-137 gamma irradiator with a dose rate of 1.8 kGy/h, and soluablefractions in water and in situ rumen liquid were determined gravimetrically. Based on these data, a reaction mechanism was proposed for the radiolysis of ligno celluloses into soluble fractions. From the corresponding reaction rate equations with this mechanism a dose dependent kinetics was derived for the radiolysis of ligno celluloses into water/rumen liquid-soluble products. Defined by this kinetics, the threshold doses for the radiolysis of the substrate into water/rumen liquid-soluble products were respectively found 80.6 kGy and 186.0 kGy, and fractional radiolytic decomposition yields 0.193 MGy''-1''.It was emphasized that developed kinetic models may be used for the process design of irradiation pretreatments to improve the bio hydrolysis of ligno celluloses.(2figs. and 17 refs.)

Thorium Fuel Utilization Analysis on Small Long Life Reactor for Different Coolant Types

Science.gov (United States)

Permana, Sidik

2017-07-01

A small power reactor and long operation which can be deployed for less population and remote area has been proposed by the IAEA as a small and medium reactor (SMR) program. Beside uranium utilization, it can be used also thorium fuel resources for SMR as a part of optimalization of nuclear fuel as a “partner” fuel with uranium fuel. A small long-life reactor based on thorium fuel cycle for several reactor coolant types and several power output has been evaluated in the present study for 10 years period of reactor operation. Several key parameters are used to evaluate its effect to the reactor performances such as reactor criticality, excess reactivity, reactor burnup achievement and power density profile. Water-cooled types give higher criticality than liquid metal coolants. Liquid metal coolant for fast reactor system gives less criticality especially at beginning of cycle (BOC), which shows liquid metal coolant system obtains almost stable criticality condition. Liquid metal coolants are relatively less excess reactivity to maintain longer reactor operation than water coolants. In addition, liquid metal coolant gives higher achievable burnup than water coolant types as well as higher power density for liquid metal coolants.

Development of lead-bismuth coolant technology for nuclear device

International Nuclear Information System (INIS)

Kamata, Kin-ya; Kitano, Teruaki; Ono, Mikinori

2004-01-01

Liquid lead-bismuth is a promising material as a future fast reactor coolant or an intensive neutron source material for accelerator driven transmutation system (ADS). To develop nuclear plants and their installations using lead-bismuth coolant for practical use, both coolant technologies, inhabitation process of steels and quality control of coolant, and total operation system for liquid lead-bismuth plants are required. Based on the experience of liquid metal coolant, Mitsui Engineering and Shipbuilding Co., Ltd. (MES) has completed the liquid lead-bismuth forced circulation loop and has acquired various engineering data on main components including economizer. As a result of tis operation, MES has developed key technologies of lead-bismuth coolant such as controlling of oxygen content in lead-bismuth and a purification of lead-bismuth coolant. MES participated in the national project, ''The Development of Accelerator Driven Transmutation System'', together with JAERI (Japan Atomic Energy Research Institute) and started corrosion test for beam window of ADS. (author)

Device for preventing coolant outflow in a reactor

International Nuclear Information System (INIS)

Nemoto, Kiyomitsu; Mochizuki, Keiichi.

1975-01-01

Object: To prevent outflow of coolant from a reactor vessel even in an occurrence of leaking trouble at a low position in a primary cooling system or the like in the reactor vessel. Structure: An inlet at the foremost end of a coolant inlet pipe inserted into a reactor vessel is arranged at a level lower than a core, and a check valve is positioned at a level higher than the core in a rising portion of the inlet. In normal condition, the check valve is pushed up by discharge pressure of a main circulating pump and remains closed, and hence, producing no flow loss of coolant, sodium. However, when a trouble such as rupture occurs at the lower position in the primary cooling system, the attractive force for allowing the coolant to back-flow outside the reactor vessel and the load force of the coolant within the reactor vessel cause the check valve to actuate, as a consequence of which a liquid level of the coolant downwardly moves to the position of the check valve to intake the cover gases into a gas intake, thereby cutting off a flow passage of the coolant to stop outflow thereof. (Kamimura, M.)

Method of charging instruments into liquid metal coolant

International Nuclear Information System (INIS)

Yamazaki, Hiroshi

1980-01-01

Purpose: To alleviate the thermal shock of a reactor charging machine when charging the machine into liquid metal coolant after the machine is preheated in cover gas. Method: When a reactor fueling machine reaches at the lowermost portion the position immediately above liquid metal coolant surface level, the machine is stopped moving down. The reactor fueling machine is heated at the lowermost portion by thermal radiation from the surface of the liquid metal coolant. After the machine is thus preheated in cover gas, it is again steadily moved down by a winch and charged into the liquid metal coolant. Therefore, the thermal shock of the machine becomes low when charging the machine into the liquid metal coolant to eliminate the damage and deformation at the machine. (Yoshihara, H.)

Effects of Water Radiolysis in Water Cooled Reactors, NERI Proposal No.99-0010

International Nuclear Information System (INIS)

Pimblott, S.M.

2000-01-01

OAK B188 Effects of Water Radiolysis in Water Cooled Reactors, NERI Proposal No.99-0010. The aim of this project is to develop an experiment-and-theory based model for the radiolysis of nonstandard aqueous systems like those that will be encountered in the Advance Light Water reactor. Three aspects of the radiation chemistry of aqueous systems at elevated temperatures are considered in the project: the radiation-induced reaction within the primary track and with additives, the homogeneous production of H 2 O 2 at high radiation doses, and the heterogeneous reaction of the radiation-induced species escaping the track. The goals outlined for Phase 1 of the program were: the compilation of information on the radiation chemistry of water at elevated temperatures, the simulation of existing experimental data on the escape yields of e aq - , OH, H 2 and H 2 O 2 in γ radiolysis at elevated temperatures, the measurement of low LET and high LET production of H 2 O 2 at room temperature, the compilation of information on the radiation chemistry of water-(metal) oxide interfaces, and the synthesis and characterization the heterogeneous water-oxide systems of interest

Radiolysis in nature: Evidence from the Oklo natural reactors

International Nuclear Information System (INIS)

Curtis, D.B.; Gancarz, A.J.

1983-02-01

An examination of the mineralogy of the reactor zones at Oklo shows that they have been significantly altered. The rocks immediately adjacent to these zones are also mineralogically modified with respect to normal uranium bearing rocks. The mineralogic changes appear to be the consequence of radiation damage, changes in the bulk chemistry of the system and increased temperatures. Chemical changes were the consequence of convectively circulating fluids that transported elements in and out of the rocks. There were also changes in the electrochemical conditions in the rocks. These changes can most reasonably be attributed to oxidizing and reducing species produced by the radiolysis of water. We have calculated radiation doses and examined the production of radiolysis products in the fluid phase which lead to the following conclusions: 1) There was a net reduction of iron, probably associated with a net increase in total iron in the rocks of the reactor zones. The reduction of iron was most likely the result of hydrogen produced by the radiolysis of water. 2) Commensurate with the iron reduction, there was an oxidation of uranium and multivalent fission products, resulting in their transport out of the reactor zone. 3) Approximately 10 percent of the uranium and various proportions of these fission products were removed and redeposited in rocks within a few meters of the reactor zones. 4) The calculated radiation doses from alpha radiation and the inferred hydrogen production suggest an effective radiation yield of 0.06 molecules of hydrogen per 100 eV of energy imparted to the fluid phase. Considering radiation from both alpha and beta sources, the G value for hydrogen production is reduced to 0.01 to 0.002 molecules H 2 /100 eV. (author)

Preliminary design of reactor coolant pump canned motor for AC600

International Nuclear Information System (INIS)

Deng Shaowen

1998-01-01

The reactor coolant pump canned motor of AC600 PWR is the kind of shielded motors with high moment of inertia, high reliability, high efficiency and nice starting performance. The author briefly presents the main feature, design criterion and technical requirements, preliminary design, computation results and analysis of performance of AC600 reactor coolant pump canned motor, and proposes some problems to be solved for study and design of AC600 reactor coolant pump canned motor

Improvement of Measurement Accuracy of Coolant Flow in a Test Loop

Energy Technology Data Exchange (ETDEWEB)

Hong, Jintae; Kim, Jong-Bum; Joung, Chang-Young; Ahn, Sung-Ho; Heo, Sung-Ho; Jang, Seoyun [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2015-10-15

In this study, to improve the measurement accuracy of coolant flow in a coolant flow simulator, elimination of external noise are enhanced by adding ground pattern in the control panel and earth around signal cables. In addition, a heating unit is added to strengthen the fluctuation signal by heating the coolant because the source of signals are heat energy. Experimental results using the improved system shows good agreement with the reference flow rate. The measurement error is reduced dramatically compared with the previous measurement accuracy and it will help to analyze the performance of nuclear fuels. For further works, out of pile test will be carried out by fabricating a test rig mockup and inspect the feasibility of the developed system. To verify the performance of a newly developed nuclear fuel, irradiation test needs to be carried out in the research reactor and measure the irradiation behavior such as fuel temperature, fission gas release, neutron dose, coolant temperature, and coolant flow rate. In particular, the heat generation rate of nuclear fuels can be measured indirectly by measuring temperature variation of coolant which passes by the fuel rod and its flow rate. However, it is very difficult to measure the flow rate of coolant at the fuel rod owing to the narrow gap between components of the test rig. In nuclear fields, noise analysis using thermocouples in the test rig has been applied to measure the flow velocity of coolant which circulates through the test loop.

Enhanced safety margins during wet transport of irradiated fuel by catalytic recombination of radiolysis hydrogen and oxygen

International Nuclear Information System (INIS)

Spencer, J.T.; Bankhead, M.; Hodge, N.A.

2004-01-01

BNFL has developed and tested a new method for use in wet transport of irradiated fuel. The method uses a catalyst to recombine the hydrogen and oxygen produced from radiolysis. The catalyst is installed in the nitrogen ullage gas region. It has twin benefits as it eliminates a gas mixture that could, in principle, exceed the safe target levels set to ensure safety during Transport, and it also reduces overall gas pressure. Pure water radiolysis predictions, from experiment and theory, indicate very low levels of hydrogen and oxygen generation. BNFL's historic experience is that in some transport packages it is possible to produce higher levels of hydrogen and oxygen. This drives the need to improve on our existing ullage gas remediation technology. Our studies of the radiolysis science and our flask data suggest it is the interaction of the liquors and material surfaces that is giving rise to the enhanced levels of hydrogen and/or oxygen. This technical paper demonstrates the performance of the recombiner catalyst under normal and extreme conditions of transport. The paper will present experimental data that shows the recombiner catalyst working to manage the hydrogen and oxygen levels

Reactor auxiliary cooling facility and coolant supplying method therefor

International Nuclear Information System (INIS)

Ando, Koji; Kinoshita, Shoichiro.

1996-01-01

A reactor auxiliary cooling facility of the present invention comprises a coolant recycling line for recycling coolants by way of a reactor auxiliary coolant pump and a cooling load, a gravitational surge tank for supplying coolants to the coolant recycling line and a supplemental water supplying line for supplying a supply the supplemental water to the tank. Then, a pressurization-type supply water surge tank is disposed for operating the coolant recycling line upon performing an initial system performance test in parallel with the gravitational surge tank. With such a constitution, the period of time required from the start of the installation of reactor auxiliary cooling facilities to the completion of the system performance test can be shortened at a reduced cost without enlarging the scale of the facility. (T.M.)

Reactor auxiliary cooling facility and coolant supplying method therefor

Energy Technology Data Exchange (ETDEWEB)

Ando, Koji; Kinoshita, Shoichiro

1996-06-07

A reactor auxiliary cooling facility of the present invention comprises a coolant recycling line for recycling coolants by way of a reactor auxiliary coolant pump and a cooling load, a gravitational surge tank for supplying coolants to the coolant recycling line and a supplemental water supplying line for supplying a supply the supplemental water to the tank. Then, a pressurization-type supply water surge tank is disposed for operating the coolant recycling line upon performing an initial system performance test in parallel with the gravitational surge tank. With such a constitution, the period of time required from the start of the installation of reactor auxiliary cooling facilities to the completion of the system performance test can be shortened at a reduced cost without enlarging the scale of the facility. (T.M.)

Pulse radiolysis experiments: synthesis and analysis of composite spectra

Energy Technology Data Exchange (ETDEWEB)

Schuler, R H; Buzzard, G K [Carnegie-Mellon Univ., Pittsburgh, Pa. (USA). Dept. of Chemistry

1976-01-01

Methods are outlined for compiling optical spectra obtained in pulse radiolysis experiments in a form suitable for detailed synthesis and analysis of composite spectra. The experimental data are processed with a programmable calculator having a cassette recorder for the storage of the output data files and a peripheral plotter. The spectra are first smoothed by fitting them parabolically segment by segment. The overall spectrum is then assembled in digital form by interpolating the fitted data on a 1 nm grid and the results are stored on cassette files for further processing. Composite spectra can be readily calculated and plotted from the data on these files or known components can be subtracted from observed spectra to examine underlying contributions. The use of the fairly simple data processing methods described here permits an interactive mode of operation by the investigator which can maximize insight into details of the various contributions to an observed spectrum. Several examples of the use of these methods in conjunction with data obtained with a computer controlled pulse radiolysis data acquisition system are given.

Picosecond radiolysis of ionic liquids

International Nuclear Information System (INIS)

Funston, A.M.; Wishart, J.F.; Neta, P.; Lall, S.I.; Engel, R.

2003-01-01

Ionic liquids (ILs) are a rapidly expanding family of condensed-phase media with important applications in nuclear fuel and waste processing, energy production, improving the efficiency and safety of industrial chemical processes, and pollution prevention. Ionic liquids are completely nonvolatile, noncombustible, highly conductive, recyclable and capable of dissolving a wide variety of materials. An understanding of the radiation chemistry of ionic liquids is important for development of their applications in radioactive material processing and for the application of pulse radiolysis techniques to the general study of chemical reactivity in ionic liquids. Kinetic studies with a picosecond electron accelerator, such as the BNL Laser-Electron Accelerator Facility (LEAF), allow one to observe primary radiation products and their reactions on short time scales. For example, the solvated electron lifetime in neat methyltributylammonium bis(trifluoromethylsulfonyl)imide is ∼300 ns and its absorption maximum is ∼1400 nm. Kinetic studies of primary radiolytic products and their reactivities will be described for several types of ionic liquids. Supported in part by the U.S. Department of Energy, Division of Chemical Sciences, Office of Basic Energy Sciences, under contract DE-AC02-98-CH1088

Coolant clean up system in nuclear reactor

International Nuclear Information System (INIS)

Tajima, Fumio; Iwami, Hiroshi.

1981-01-01

Purpose: To decrease the amount of main steams and improve the plant heat efficiency by the use of condensated water as coolants for not-regenerative heat exchangers in a coolant clean up system of a nuclear reactor. Constitution: In a coolant clean up system of a nuclear reactor, a portion of condensates is transferred to the shell of a non-regenerative heat exchanger by way of a condensate pump for non-regenerative heat exchanger through a branched pipeway provided to the outlet of a condensate desalter for using the condensates as the coolants for the shell of the heat exchanger and the condensates are then returned to the inlet of a feedwater heater after the heat exchange. The branched flow rate of the condensates is controlled by the flow rate control valve mounted in the pipeway. Condensates passed through the heat exchanger and the condensates not passed through the heat exchanger are mixed and heated in a heater and then fed to the nuclear reactor. In a case where no feedwater is necessary to the nuclear reactor such as upon shutdown of the reactor, the condensates are returned by way of feedwater bypass pipeway to the condensator. By the use of the condensates as the coolants for the heat exchanger, the main steam loss can be decreased and the thermal load for the auxiliary coolant facility can be reduced. (Kawakami, Y.)

γ-Ray radiolysis and theoretical study on radical ions of star-shaped oligofluorenes having a truxene or isotruxene as a core

International Nuclear Information System (INIS)

Fujitsuka, Mamoru; Tojo, Sachiko; Yang, Jye-Shane; Majima, Tetsuro

2013-01-01

Highlights: ► Radiolysis provides absorption spectra of radical ions of star-shaped oligofluorenes. ► Absorption spectroscopic properties depend on oligomer size extensively. ► TDDFT provides reasonable assignments to the visible and near-IR absorption bands. ► Extensive charge delocalization was indicated by planarization of oligomers. - Abstract: Poly- and oligofluorenes have been intensively studied for years, because of their excellent properties as photo- and electro-functional materials. Especially, star-shaped oligofluorenes as two-dimensional oligomers are interesting materials for wide researchers. To understand their electronic properties in charged states, absorption spectra of radical cation and radical anion of star-shaped oligomers with varied size were investigated by means of γ-ray radiolysis. The absorption spectra of their radical ions ranged from the visible to near-IR regions were successfully obtained. By using the theoretical calculation, the observed peaks were assigned. It is indicated that the transition between HOMO and LUMO of the original neutral state plays a significant role in the visible region. Furthermore, it is indicated that the star-shaped oligofluorenes tend to take a planar structure upon oxidation and reduction

A comparative neutronic analysis of KALIMER breeder core using Na or Pb-Bi coolant

International Nuclear Information System (INIS)

Yoo, J. W.; Kim, S. J.; Kim, Y. I.

2000-01-01

A comparative neutronic study has been conducted on KALIMER breeder core according to the replacement of sodium coolant by Pb-Bi coolant. Since the atomic weight of Pb and Bi is about 9 times heavier than that of Na, the energy loss by neutron colliding with Pb-Bi nucleus will be very small. Therefore, the reactor with Pb-Bi coolant will have a harder neutron spectrum than that with Na coolant. Consequently, the breeding ratio and burnup reactivity swing is expected to be enhanced. In addition, when Pb-Bi coolant is voided, a negative coolant void coefficient can be obtained by the net effects of smaller spectrum hardening and large neutron leakage. As a result, the breeding ratio was increased from 1.18 to 1.23 and burnup reactivity swing was reduced from 631 pcm to 150 pcm. When the coolant in the whole region of active core is voided, the coolant void coefficient was found to be -539 and -264 pcm at BOEC and EOEC, respectively. In the local voided case, the smaller coolant void coefficient was obtained than that of Na coolant. Accordingly, the use of Pb-Bi coolant in KALIMER gives an advantage of higher breeding ratio, smaller burnup reactivity swing and negative coolant void coefficient without any significant degradation of nuclear performance

Continuous surveillance of reactor coolant circuit integrity

International Nuclear Information System (INIS)

1986-01-01

Continuous surveillance is important to assuring the integrity of a reactor coolant circuit. It can give pre-warning of structural degradation and indicate where off-line inspection should be focussed. These proceedings describe the state of development of several techniques which may be used. These involve measuring structural vibration, core neutron noise, acoustic emission from cracks, coolant leakage, or operating parameters such as coolant temperature and pressure. Twenty three papers have been abstracted and indexed separately for inclusion in the data base

NPP capital equipment life control facilities and tools

International Nuclear Information System (INIS)

Nekrasov, A.V.; Proskuryakov, K.N.

2009-01-01

Algorithms and simulation package for calculation of eigen modes of coolant pressure oscillations in equipment of primary coolant circuit of WWER-1000 NPP, tuned-circuit Q-factor of an oscillating contour of the coolant, fluctuation frequencies pass band and attenuation factors of were developed. Calculation results for cases of presence and absence of gaseous state radiolysis products in the coolant were obtained. Results analysis makes it possible to disclose operating conditions which result in raised vibrations, and to develop control response in NPP industrial control system for their prevention [ru

Gamma radiolysis of C6F6, product formation

International Nuclear Information System (INIS)

Sagert, N.H.; LeBlanc, J.C.; Wood, D.D.; Kremers, W.; Westmore, J.B.; Buchannon, W.D.

1991-01-01

The γ radiolysis of perfluorobenzene (PFB) has been studied at a dose rate of about 26 Gy·s -1 and at total doses up to 10 5 Gy. Radiolyses were carried out in fluorine-passivated nickel cells in the absence of air. There were no significant gas yields, but higher molecular weight products were observed and characterized by combined gas chromatography and mass spectrometry (GC/MS). The yield of all polymers totalled 1.7 molecules of PFB consumed for each 100 eV absorbed. This result is comparable to yields measured by earlier workers at much higher doses and dose rates. (author)

Study of the influence of radiolysis on the stability of plutonium III. Application to a heterogeneous medium formed by a nitric solution of ferrous ions and an organic solution of trilauryl-ammonium nitrate

International Nuclear Information System (INIS)

Fourmaux, J.M.

1980-01-01

The objective of this research thesis is to study the behaviour of plutonium 238 in media which are commonly used to isolate it from other elements such as neptunium and fission products created during the neutron irradiation of the neptunium 237 isotope. As plutonium 238 purification processes are all based on redox reaction, it is essential to know the influence of radiolysis on the redox behaviour, and on the distribution coefficients of this isotope in solutions used during its separation from the neptunium 237 isotope. Therefore, it is necessary to study the influence of radiolysis on the stability of plutonium with an oxidation III level. As this extraction is performed by an organic solvent (trilauryl-ammonium nitrate), this study addresses the behaviour of plutonium in an emulsion formed by this solvent and the nitric aqueous solution previously adjusted in terms of Fe 2+ ions. After a brief recall of bibliographical generalities related to radiolysis, the author presents and comments the Nernst law in the case of a two-phase system (emulsion), and reports the use of this law to obtain the plutonium potential-distribution coefficient relationship. The last part reports experimental data

Measurement of the hydrogen yield in the radiolysis of water by dissolved fission products

International Nuclear Information System (INIS)

Sauer, M.C. Jr.; Hart, E.J.; Flynn, K.F.; Gindler, J.E.

1976-04-01

Hydrogen from the radiolysis of water by dissolved fission products is stripped from the solution and collected by bubbling CO 2 through the solution. Quantitative measurements of the G value for hydrogen show that the yield is essentially the same as would be obtained by external gamma radiolysis of nonradioactive solutions of the same chemical composition. The hydrogen yield can be enhanced by addition of a hydrogen-atom donor, such as formic acid, to the solution. The yield of hydrogen from fission-waste solutions is discussed with respect to the question of whether it represents a significant energy source

Mathematical modeling of water radiolysis in the Syrian MNSR reactor

International Nuclear Information System (INIS)

Soukieh, M.

2009-11-01

Because it is difficult to measure the concentration of the radiolytic species in reactors under operating conduction, they must be estimated by computer simulation techniques. This study discusses the mathematical modeling of water radiolysis modeling of the MNSR nuclear reactor cooling water. The mathematical model comprising of 13 differential equations describe 55 chemical reactions of radiolytic species e - a q H + , OH - , H, H 2 , OH, HO 2 , O 2 , HO - 2 , O - , O - 2 , O - 3 . The mathematical model have been tested and it shows a good agreement of the computed values in this work with the results cited in references [1,18] in case of only γray irradiation of pure water with dose rate of 1.18x10 19 eV/L s. The neutron fluxes and dose rates at the interface of cladding-water for the different fuel rings in the MNSR core are determined using MCNP-4C code. In addition, the time dependent of the radiolytic specie concentrations were estimated for max. and min. dose rates and at temperature of 20 degree centigrade in the MNSR. The radiolytic specie concentrations reach the steady sate after about 200-400 s. The radiolytic specie concentrations order of H 2 , O 2 , H 2 O 2 were about ppb. Also this study shows the possibility of suppressed the water radiolysis reactions by adding hydrogen to the MNSR reactor cooling water. (author)

Pulse radiolysis studies concerning oxidative degradation processes in linear polymers

International Nuclear Information System (INIS)

Schnabel, Wolfram

1986-01-01

On the basis of pulse radiolysis experiments carried out with various polymers in dilute solution three modes of action of molecular oxygen, 0 2 , can be discriminated with respect to main-chain scission: (a) 0 2 acts as a promoter, (b) 0 2 acts as an inhibitor, and (c) 0 2 acts as a fixing agent for main-chain breaks. The promoting mode of action (a) is due to the inhibition of simultaneously occurring intermolecular crosslinking (DNA, polymethylvinylketone) and/or to the combination of peroxyl radicals with the subsequent formation of readily decomposing oxyl radicals (polyethylene oxide, polyacrylamide, polyvinylpyrrolidone, polyribouridylic acid, polyriboadenylic acid, polyribocytidylic acid). The inhibiting mode of action (b) pertains to the reaction of 0 2 with macroradicals that otherwise undergo main-chain rupture (amylose polymethylmethacrylate). Fixing of main-chain ruptures (mode c) becomes important, if macroradicals generated by a very fast rupture of bonds in the main-chain, are prone to recombine quickly. This mode of action was evidenced in the case of polybutenesulfone where main-chain scission involves the extrusion of small segments of the chain. (author)

Decontamination of main coolant pumps

International Nuclear Information System (INIS)

Roofthooft, R.

1988-01-01

Last year a number of main coolant pumps in Belgian nuclear power plants were decontaminated. A new method has been developed to reduce the time taken for decontamination and the volume of waste to be treated. The method comprises two phases: Oxidation with permanganate in nitric acid and dissolution in oxalic acid. The decontamination of main coolant pumps can now be achieved in less than one day. The decontamination factors attained range between 15 and 150. (orig.) [de

Monte Carlo simulation of chemistry following radiolysis with TOPAS-nBio

Science.gov (United States)

Ramos-Méndez, J.; Perl, J.; Schuemann, J.; McNamara, A.; Paganetti, H.; Faddegon, B.

2018-05-01

Simulation of water radiolysis and the subsequent chemistry provides important information on the effect of ionizing radiation on biological material. The Geant4 Monte Carlo toolkit has added chemical processes via the Geant4-DNA project. The TOPAS tool simplifies the modeling of complex radiotherapy applications with Geant4 without requiring advanced computational skills, extending the pool of users. Thus, a new extension to TOPAS, TOPAS-nBio, is under development to facilitate the configuration of track-structure simulations as well as water radiolysis simulations with Geant4-DNA for radiobiological studies. In this work, radiolysis simulations were implemented in TOPAS-nBio. Users may now easily add chemical species and their reactions, and set parameters including branching ratios, dissociation schemes, diffusion coefficients, and reaction rates. In addition, parameters for the chemical stage were re-evaluated and updated from those used by default in Geant4-DNA to improve the accuracy of chemical yields. Simulation results of time-dependent and LET-dependent primary yields Gx (chemical species per 100 eV deposited) produced at neutral pH and 25 °C by short track-segments of charged particles were compared to published measurements. The LET range was 0.05–230 keV µm‑1. The calculated Gx values for electrons satisfied the material balance equation within 0.3%, similar for protons albeit with long calculation time. A smaller geometry was used to speed up proton and alpha simulations, with an acceptable difference in the balance equation of 1.3%. Available experimental data of time-dependent G-values for agreed with simulated results within 7%  ±  8% over the entire time range; for over the full time range within 3%  ±  4% for H2O2 from 49%  ±  7% at earliest stages and 3%  ±  12% at saturation. For the LET-dependent Gx, the mean ratios to the experimental data were 1.11  ±  0.98, 1.21  ±  1.11, 1.05�

Pulse radiolysis of rhodamine dye solutions

International Nuclear Information System (INIS)

Kucherenko, E.A.; Kartasheva, L.I.; Pikaev, A.K.

1982-01-01

Applying the method of pulse radiolysis (5 MeV electrons) a study was made on intermediate products of rhodamine B radiolytic transformations in neutral aqueous and ethanol solutions. Rate constants of reactions of esub(aq) and OH with the dye (they are equal to (2.2+-0.3)x10 10 and (2.1+-0.3)x10 10 e/molxs, accordingly) as well as optical and kinetic characteristics of esub(aq), OH and H interaction products were measured. The nature of these products is concluded. It was found that in ethanol solutions the semirecovered form - electroneutral radical of rhodamine B - was the only intermediate product. It arises during the interaction of the dye with esub(s) (k=(9.2+-1.2)x10 9 e/molxs) and α-et hananol radical (k=(1.1+-0.1)x10 8 l/molxs). Properties of this product were investigated

Liquid metal coolant disposal from UKAEA reactors at Dounreay

International Nuclear Information System (INIS)

Adam, E.R.

1997-01-01

As part of the United Kingdom's Fast Reactor Development programme two reactors were built and operated at Dounreay in the North of Scotland. DFR (Dounreay Fast Reactor) was operated from 1959-1977 and PFR (Prototype Fast Reactor) was operated from 1974-1994. Both reactors are currently undergoing Stage 1 Decommissioning and are installing plant to dispose of the bulk coolant (DFR ∼ 60 tonne; PFR ∼ 1500 tonne). The coolant (NaK) remaining at DFR is mainly in the primary circuit which contains in excess of 500 TBq of Cs137. Disposal of 40 tonnes of secondary coolant has already been carried out. The paper will describe the processes used to dispose of this secondary circuit coolant and how it is intended the remaining primary circuit coolant will be handled. The programme to process the primary coolant will also be described which involves the conversion of the liquid metal to caustic and its decontamination. No PFR coolant Na has been disposed off to date. The paper will describe the current decommissioning programme activities relating to liquid metal disposal and treatment describing the materials to be disposed of and the issue of decontamination of the effluents. (author)

Radiolysis of aqueous solutions of ammonium bicarbonate over a large dose range

International Nuclear Information System (INIS)

Draganic, Z.D.; Draganic, I.G.; Negron-Mendoza, A.; Navarro-Gonzales, R.; Albarran-Sanchez, M.G.; Sehested, K.

1986-12-01

0 2 -free aqueous solutions of 0.05 mol dm -3 ammonium bicarbonate were studied after receiving various doses of 60 Co gammas (0.001-170 Mrd) or krd pulses of 10 MeV electrons. Formate, oxalate, formaldehyde and an unidentified polymer (M w 14000-16000 daltons) were found to be the main radiolytic products. A large initial yield of formate in the γ-radiolysis, G(HCOO - ) = 2.2, is due to the reaction CO 2 - + HCO 3 - ↔ HC00 - + CO 3 - . The efficiency of organic synthesis within the large dose range studied is low and is explained by efficient pathways to the reformation of bicarbonate, where the reaction CO 2 - + CO 3 - is particurlarly significant. Computer fitting of the data obtained in the γ-radiolysis and by pulsed electron beam experiments gives k(CO 2 - + HCO 3 - ) = (2 ± 0.4)x10 3 dm 3 mol -1 s -1 , k(CO 2 - + CO 3 - ) = (5 ± 1)x10 7 dm 3 mol -1 s -1 , k(NH 2 + = HCO 3 - ) 4 dm 3 mol -1 s -1 and k(NH 2 + CO 3 - ) = (1.5 ± 0.5)x10 9 dm 3 mol -1 s -1 . (author)

Organic coolants and their applications to fusion reactors

International Nuclear Information System (INIS)

Gierszewski, P.; Hollies, B.

1986-08-01

Organic coolants offer a unique set of characteristics for fusion applications. Their advantages include high-temperature (670 K or 400 degrees C) but low-pressure (2 MPa) operation, limited reactivity with lithium and lithium-lead, reduced corrosion and activation, good heat-transfer capabilities, no magnetohydrodynamic (MHD) effects, and an operating temperature range that extends to room temperature. The major disadvantages are decomposition and flammability. However, organic coolants have been extensively studied in Canada, including nineteen years with an operating 60-MW organic-cooled reactor. Proper attention to design and coolant chemistry controlled these potential problems to acceptable levels. This experience provides an extensive data base for design under fusion conditions. The organic fluid characteristics are described in sufficient detail to allow fusion system designers to evaluate organic coolants for specific applications. To illustrate and assess the potential applications, analyses are presented for organic-cooled blankets, first walls, high heat flux components and thermal power cycles. Designs are identified that take advantage of organic coolant features, yet have fluid decomposition related costs that are a small fraction of the overall cost of electricity. For example, organic-cooled first walls make lithium/ferritic steel blankets possible in high-field, high-surface-heat-flux tokamaks, and organic-cooled limiters (up to about 8 MW/m 2 surface heating) are a safer alternative to water cooling for liquid metal blanket concept. Organics can also be used in intermediate heat exchanger loops to provide efficient heat transfer with low reactivity and a large tritium barrier. 55 refs

Evaluation of alternate secondary (and tertiary) coolants for the molten-salt breeder reactor

International Nuclear Information System (INIS)

Kelmers, A.D.; Baes, C.F.; Bettis, E.S.; Brynestad, J.; Cantor, S.; Engel, J.R.; Grimes, W.R.; McCoy, H.E.; Meyer, A.S.

1976-04-01

The three most promising coolant selections for an MSBR have been identified and evaluated in detail from the many coolants considered for application either as a secondary coolant in 1000-MW(e) MSBR configurations using only one coolant, or as secondary and tertiary coolants in an MSBR dual coolant configuration employing two different coolants. These are, as single secondary coolants: (1) a ternary sodium--lithium--beryllium fluoride melt; (2) the sodium fluoroborate--sodium fluoride eutectic melt, the present reference design secondary coolant. In the case of the dual coolant configuration, the preferred system is molten lithium--beryllium fluoride (Li 2 BeF 4 ) as the secondary coolant and helium gas as the tertiary coolant

Spin trapping study on the nature of radicals generated by X radiolysis and peroxidation of linolenic acid

International Nuclear Information System (INIS)

Azizova, O.A.; Osipov, A.N.; Zubarev, V.E.; Yakhyaev, A.V.; Vladimirov, Yu.A.; Savov, V.M.; Kagan, V.E.

1983-01-01

The radicals of linolenic acid and their spin adducts (SA) with PBN formed during X radiolysis of linolenic acid and in lipid peroxidation with ferrous ions were investigated and identified. It was found that in the absence of oxygen in pure linolenic acid at 77 K X irradiation produces alkyl and carboxyl radicals. In the presence of the spin trap alkyl radical spin adducts were formed. Irradiation of linolenic acid in the presence of oxygen at 77 K also resulted in the formation of alkyl radicals. These radicals were transformed into peroxy radicals in the interaction of alkyl radical with oxygen upon heating to 117 K. In the presence of spin trap X irradiation of linolenic acid and heating of the sample up to 300 K gave rise to EPR spectra of SA alkyl and unidentified radicals. Lipid peroxidation of linolenic acid induced by ferrous ions in the presence of spin trap also formed radicals and SA of linolenic acid. The spectral parameters of SA generated with ferrous ions in lipid peroxidation and of those generated during X radiolysis do not differ. The similarity of spectral parameters of SA in these two cases suggests a similarity in the structure of linolenic acid radicals. (author)

Pulse Radiolysis of Adrenaline in Acid Aqueous Solutions

DEFF Research Database (Denmark)

Gohn, M.; Getoff, N.; Bjergbakke, Erling

1976-01-01

Pulse radiolysis of adrenaline in acid aqueous solutions (pH 1–3) was carried out. The rate constants for the reactions of adrenaline with H and OH were determined: k(H + adr.) = (0·9±0·1) × 109 dm3 mol−1s−1; k(OH + adr.) = (1·65±0·15) × 1010 dm3 mol−1s−1. The H-adduct of adrenaline has two λmax...

Comparative radiosensitivity of amino acids during γ-radiolysis in aqueous solutions

International Nuclear Information System (INIS)

Duzhenkova, N.A.; Savich, A.V.

1977-01-01

The radiosensitivity of amino acids contained in proteins has been compared. The γ-radiolysis of aqueous solutions of amino acids has studied over a wide range of concentrations in the presence of air, the dose rate being 60 rad/sec, and the dose, 100 krad. Radiation-chemical yields of amino acid decay and ammonia accumulation are given. An increase in yields with amino acid concentration has been established. Assumptions concerning some peculiarities of the amino acid decay mechanism are made

Experimental study on thermal-hydraulic behaviors of a pressure balanced coolant injection system for a passive safety light water reactor JPSR

Energy Technology Data Exchange (ETDEWEB)

Satoh, Takashi; Watanabe, Hironori; Araya, Fumimasa; Nakajima, Katsutoshi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Iwamura, Takamichi; Murao, Yoshio

1998-02-01

A conceptual design study of a passive safety light water reactor JPSR has been performed at Japan Atomic Energy Research Institute JAERI. A pressure balanced coolant injection experiment has been carried out, with an objective to understand thermal-hydraulic characteristics of a passive coolant injection system which has been considered to be adopted to JPSR. This report summarizes experimental results and data recorded in experiment run performed in FY. 1993 and 1994. Preliminary experiments previously performed are also briefly described. As the results of the experiment, it was found that an initiation of coolant injection was delayed with increase in a subcooling in the pressure balance line. By inserting a separation device which divides the inside of core make-up tank (CMT) into several small compartments, a diffusion of a high temperature region formed just under the water surface was restrained and then a steam condensation was suppressed. A time interval from an uncovery of the pressure balance line to the initiation of the coolant injection was not related by a linear function with a discharge flow rate simulating a loss-of-coolant accident (LOCA) condition. The coolant was injected intermittently by actuation of a trial fabricated passive valve actuated by pressure difference for the present experiment. It was also found that the trial passive valve had difficulties in setting an actuation set point and vibrations noises and some fraction of the coolant was remained in CMT without effective use. A modification was proposed for resolving these problems by introducing an anti-closing mechanism. (author)

Oxidation of cinnamic acid derivatives: A pulse radiolysis and theoretical study

International Nuclear Information System (INIS)

Yadav, Pooja; Mohan, Hari; Maity, Dilip Kumar; Suresh, Cherumuttathu H.; Rao, B.S. Madhav

2008-01-01

Second order rate constants in the range of (k = 1.6-4.5) x 10 9 dm 3 mol -1 s -1 were obtained for the · OH induced oxidation of nitro- and methoxycinnamic acid derivatives in neutral solutions using pulse radiolysis. The transient absorption spectra exhibited a broad peak around 360-410 nm in o-methoxy, o- and p-nitrocinnamates or two peaks around 310-330 and 370-410 nm in other isomers. Quantum chemical calculations revealed that addition of · OH to olefinic moiety yielded considerably more stable structures than ring addition products and the para system among the latter is the most stable. Spin density analysis suggested that olefinic adducts retained the aromaticity in contrast to its loss in ring · OH adducts. An excellent linear correlation between the relative stabilities of the · OH adducts (after accounting for the aromatic stabilization in olefinic adducts) and the maximum S d values is also obtained

Identification of tetraphenylborate radiolysis products in a simulated feedstock for radioactive waste processing

International Nuclear Information System (INIS)

Eibling, R.E.; Bartlett, M.G.; Carlson, R.E.; Testino, S.A. Jr.; Kunkel, G.J.; Browner, R.F.; Busch, K.L.

1994-01-01

The first step towards immobilization of the soluble radioactive species in borosilicate glass is the addition of sodium tetraphenylborate (TPB) and sodium titanate to the radioactive aqueous solution. Initial studies of the TPB hydrolysis process have found that some component of the radiolysis mixture inactivates the Cu catalyst. The interaction of organic materials with the catalyst, and the subsequent interference with the hydrolysis process, would have presented problems with the use of the vitrification process. Prevention of the catalyst deactivation is obtained by washing the irradiated TPB precipitate in the Late Wash Facility prior to hydrolysis to remove the soluble radiolysis products. Identification of the organic radiolysis products, their distribution in the Late Wash Facility, and their interactions with the Cu catalyst has become an important analytical issue. To further investigate the reaction products of the TPB precipitation process, a simulated feedstock was created from compounds known to be present in the starting materials. This simulated feedstock was precipitated with sodium TPB and then exposed to Co-60 gamma radiation to simulate two years of additional storage time prior to the hydrolysis process. The irradiated product was divided into two parts, the filtered supernatant liquid and the precipitate slurry, which contains the TPB and the solid sodium titanate. Using gas chromatography/mass spectrometry, liquid secondary ion mass spectrometry, inductively coupled plasma/mass spectrometry, ion chromatography, and high performance liquid chromatography, over 50 organic and inorganic species have been identified in the aqueous portion of a simulated feedstock for TPB hydrolysis. The major organic species present are benzene, phenol, benzamide and a variety of substituted phenylphenols. The major inorganic species present are sodium, nitrite, and oxalate ions

A open-quotes zero wasteclose quotes coolant management strategy

International Nuclear Information System (INIS)

Kennicott, M.A.

1994-01-01

In June of 1992 the Waste Minimization Program at Rocky Flats Plant (RFP) began a study to determine the best methods of managing water-based industrial metalworking fluids in the plant's Tool Manufacturing Shop. The shop was faced with the challenge of managing fluids that could no longer be disposed of in the traditional manner, through the plant's liquid process waste drains, due to a problem they, were having causing in the Liquid Waste Operations Evaporator. The study's goal was to reduce the waste coolants being generated and to reduce worker exposure to a serious health risk. Results of this study and those of a subsequent study to determine relative compatibilities of various coolants and metals, led to the application of a open-quotes zero wasteclose quotes machine coolant management program. This program is currently saving the generation of 10,000 gallons of liquid waste annually, has eliminated worker exposure to harmful bacteria and biocides, and should result in extended machine tool life, increased product quality, fewer rejected parts, and decreases labor costs

Neutronic Analysis on Coolant Options in a Hybrid Reactor System for High Level Waste Transmutation

Energy Technology Data Exchange (ETDEWEB)

Hong, Seong Hee; Kim, Myung Hyun [Kyung Hee University, Seoul (Korea, Republic of)

2014-10-15

A fusion-fission hybrid reactor (FFHR) which is a combination of plasma fusion tokamak as a fast neutron source and a fission reactor as of fusion blanket is another potential candidate. In FFHR, fusion plasma machine can supply high neutron-rich and energetic 14.1MeV (D, T) neutrons compared to other options. Therefore it has better capability in HLW incineration. While, it has lower requirements compared to pure fusion. Much smaller-sized tokamak can be achievable in a near term because it needs relatively low plasma condition. FFHR has also higher safety potential than fast reactors just as ADSR because it is subcritical reactor system. FFHR proposed up to this time has many design concepts depending on the design purpose. FFHR may also satisfy many design requirement such as energy multiplication, tritium production, radiation shielding for magnets, fissile breeding for self-sustain ability also waste transmutation. Many types of fuel compositions and coolant options have been studied. Effect of choices for fuel and coolant was studied for the transmutation purpose FFHR by our team. In this study LiPb coolant was better than pure Li coolant both for neutron multiplication and tritium breeding. However, performance of waste transmutation was reduced with increased neutron absorption at coolant caused by tritium breeding. Also, LiPb as metal coolant has a problem of massive MHD pressure drop in coolant channels. Therefore, in a previous study, waste transmutation performance was evaluated with light water coolant option which may be a realistic choice. In this study, a neutronic analysis was done for the various coolant options with a detailed computation. One of solutions suggested is to use the pressure tubes inside of first wall and second wall In this work, performance of radioactive waste transmutation was compared with various coolant options. On the whole, keff increases with all coolants except for FLiBe, therefore required fusion power is decreased. In

Coolant void effect investigation - case of a na-cooled fast reactor

International Nuclear Information System (INIS)

Glinatsis, G.; Gugiu, D.

2013-01-01

In the frame of the last EURATOM-FP7 Program, a large sized Sodium-cooled FR (SFR) has been studied. Mixed carbides fuel (U, Pu)C has been adopted for the backup core solution and important work has been also performed in order to obtain an ''optimised'' backup configuration ''close'' to the reference one, which is fueled by mixed oxides fuel (U, Pu)Ox. The peculiarity of both core designs (the reference configuration and the optimised backup configuration) is the adoption of a 60 cm Plenum zone in the upper part of each fuel assembly (FA), that is filled by coolant, in order to mitigate (when emptied) the core positive coolant void effect. This paper presents some results of a detailed study of the coolant void effect for the above SFR with mixed carbides core. Many aspects, like geometric heterogeneity, the burnup state, the operating conditions, etc., have been taken into consideration in order to obtain information about the ''propagation'' and the behaviour of the coolant void effect itself. The performed study investigates also the coolant void effect consequences on some reactivity coefficients, which are important for a safe behaviour of the reactor. The investigation consisted in the steady state simulations of the reactor on different operating conditions in Monte Carlo approach. (authors)

Condition monitoring of main coolant pumps, Dhruva

International Nuclear Information System (INIS)

Prasad, V.; Satheesh, C.; Acharya, V.N.; Tikku, A.C.; Mishra, S.K.

2002-01-01

Full text: Dhruva is a 100 MW research reactor with natural uranium fuel, heavy water as moderator and primary coolant. Three Centrifugal pumps circulate the primary coolant across the core and the heat exchangers. Each pump is coupled to a flywheel (FW) assembly in order to meet operational safety requirements. All the 3 main coolant pump (MCP) sets are required to operate during operation of the reactor. The pump-sets are in operation since the year 1984 and have logged more than 1,00,000 hrs. Frequent breakdowns of its FW bearings were experienced during initial years of operation. Condition monitoring of these pumps, largely on vibration based parameters, was initiated on regular basis. Break-downs of main coolant pumps reduced considerably due to the fair accurate predictions of incipient break-downs and timely maintenance efforts. An effort is made in this paper to share the experience

Radiolysis of carbohydrates and of carbohydrate-containing foodstuffs

International Nuclear Information System (INIS)

Diehl, J.F.; Adam, S.; Delincee, H.; Jakubick, V.

1978-01-01

Toxicological evaluation of irradiated foodstuffs requires knowledge of radiation-induced chemical changes. A review of the literature reveals much information on the radiation chemistry of pure substances, e.g., dilute solutions of individual carbohydrates. Much less is known about the interactions of food constituents during irradiation. In an effort to remedy this situation, radiation effects on various compounds have been studied in systems of increasing complexity. In one approach, gas chromatography was used to investigate the radiolysis of tehalose in pure solution and in the presence of amino acids or proteins. In another approach, radiation-induced aggregation of proteins and of [ 14 C]tryptophan with proteins was studied in the absence and presence of carbohydrates (trehalose, starch), emulsified sunfower oil, and a mixture of carbohydrates and emulsified sunflower oil

Experimental and analytical studies of melt jet-coolant interactions: a synthesis

Energy Technology Data Exchange (ETDEWEB)

Dinh, T.N.; Bui, V.A.; Nourgaliev, R.R.; Green, J.A.; Sehgal, B.R. [Royal Inst. of Tech., Stockholm (Sweden). Div. of Nuclear Power Safety

1998-01-01

Instability and fragmentation of a core melt jet in water have been actively studied during the past ten years. Several models, and a few computer codes, have been developed. However, there are, still, large uncertainties, both, in interpreting experimental results and in predicting reactor-scale processes. Steam explosion and debris coolability, as reactor safety issues, are related to the jet fragmentation process. A better understanding of the physics of jet instability and fragmentation is crucial for assessments of fuel-coolant interactions (FCIs). This paper presents research, conducted at the Division of Nuclear Power Safety, Royal Institute of Technology (RIT/NPS), Stockholm, concerning molten jet-coolant interactions, as a precursor for premixing. First, observations were obtained from scoping experiments with simulant fluids. Second, the linear perturbation method was extended and applied to analyze the interfacial-instability characteristics. Third, two innovative approachs to CFD modeling of jet fragmentation were developed and employed for analysis. The focus of the studies was placed on (a) identifying potential factors, which may affect the jet instability, (b) determining the scaling laws, and (c) predicting the jet behavior for severe accidents conditions. In particular, the effects of melt physical properties, and the thermal hydraulics of the mixing zone, on jet fragmentation were investigated. Finally, with the insights gained from a synthesis of the experimental results and analysis results, a new phenomenological concept, named `macrointeractions concept of jet fragmentation` is proposed. (author)

Experimental and analytical studies of melt jet-coolant interactions: a synthesis

International Nuclear Information System (INIS)

Dinh, T.N.; Bui, V.A.; Nourgaliev, R.R.; Green, J.A.; Sehgal, B.R.

1999-01-01

Instability and fragmentation of a core melt jet in water have been actively studied during the past 10 years. Several models, and a few computer codes, have been developed. However, there are, still, large uncertainties, both, in interpreting experimental results and in predicting reactor-scale processes. Steam explosion and debris coolability, as reactor safety issues, are related to the jet fragmentation process. A better understanding of the physics of jet instability and fragmentation is crucial for assessments of fuel-coolant interactions (FCIs). This paper presents research, conducted at the Division of Nuclear Power Safety, Royal Institute of Technology (RIT/NPS), Stockholm, concerning molten jet-coolant interactions, as a precursor for premixing. First, observations were obtained from scoping experiments with simulant fluids. Second, the linear perturbation method was extended and applied to analyze the interfacial-instability characteristics. Third, two innovative approaches to computational fluid dynamics (CFD) modeling of jet fragmentation were developed and employed for analysis. The focus of the studies was placed on (a) identifying potential factors, which may affect the jet instability, (b) determining the scaling laws, and (c) predicting the jet behavior for severe accident conditions. In particular, the effects of melt physical properties, and the thermal hydraulics of the mixing zone, on jet fragmentation were investigated. Finally, with the insights gained from a synthesis of the experimental results and analysis results, a new phenomenological concept, named 'macrointeractions concept of jet fragmentation' is proposed. (orig.)

RETRAN analysis of inter-system LOCA within the primary coolant pump

International Nuclear Information System (INIS)

Gangadharan, A.; Pratt, G.F.

1992-01-01

One example of an inter-system loss of coolant accident is the failure of the tubing within the primary coolant pump (PCP) thermal barrier heat exchanger. Such a failure would result in the entry of primary coolant into the component cooling water (CCW) system. The primary coolant flowrate through the break would rapidly pressurize the CCW system when the relief valves are too small. The piping in the CCW system at Palisades has a low pressure rating. Failures in this system outside the containment boundary could lead to primary coolant release to the atmosphere. RETRAN-02 was used to perform a simulation of the break in the PCP integral heat exchanger. The model included a detailed nodalization of the Byron-Jackson primary coolant pump internals leading up to the CCW system relief valves. Preliminary studies show the need for increased relief capacity in the CCW system. A case was run using a larger relief valve. Critical flow in the system upstream of the relief valves maintains the pressures in those volumes above the CCW design pressure. The pressures downstream from the relief valves and outside containment will be at or below the design pressure. This paper presents the results of the transient analysis

Development of nuclear transmutation technology - A study on the thermal-hydraulic characteristics of Pb-Bi coolant material

Energy Technology Data Exchange (ETDEWEB)

Chung, Chang Hyun; You, Young Woo; Cho, Jae Seon; Kim, Ju Youl; Yang, Hui Chang; Huh, Byung Gil [Seoul National University, Seoul (Korea)

2000-03-01

The objective of this study is to provide the direction of HYPER design in terms of thermal hydraulics especially through the analysis of thermal hydraulic characteristics of lead-bismuth material as a HYPER coolant and of proton accelerator target system. In this study, in order to evaluate the thermal-hydraulic characteristics of HYPER system, the FLUENT calculation is performed with liquid metal lead-bismuth(43%) and the turbulent Prandtl number model is developed. Also, the heat transfer analyses including temperature rising are performed for accelerator beam window, solid tungsten target and liquid target which is composed of liquid lead and lead-bismuth, respectively and the thermal stress analyses are performed for accelerator beam window. Through this study, the BASECASE whose parameter is HYPER system design specification is calculated by FLUENT. It is shown that the coolant velocity must exceeds 1.6 m/s for supporting the core coolant temperature in operating temperature range. The suggested turbulent Prandtl number model is applicable to liquid metal. And in order to maintain the integrity of proton beam target system, it is necessary to investigate the target structure associated with smoothing the flow path and beam window cooling. 43 refs., 67 figs., 27 tabs. (Author)

Performance Analysis of Thermoelectric Based Automotive Waste Heat Recovery System with Nanofluid Coolant

Directory of Open Access Journals (Sweden)

Zhi Li

2017-09-01

Full Text Available Output performance of a thermoelectric-based automotive waste heat recovery system with a nanofluid coolant is analyzed in this study. Comparison between Cu-Ethylene glycol (Cu-EG nanofluid coolant and ethylene glycol with water (EG-W coolant under equal mass flow rate indicates that Cu-EG nanofluid as a coolant can effectively improve power output and thermoelectric conversion efficiency for the system. Power output enhancement for a 3% concentration of nanofluid is 2.5–8 W (12.65–13.95% compared to EG-Water when inlet temperature of exhaust varies within 500–710 K. The increase of nanofluid concentration within a realizable range (6% has positive effect on output performance of the system. Study on the relationship between total area of thermoelectric modules (TEMs and output performance of the system indicates that optimal total area of TEMs exists for maximizing output performance of the system. Cu-EG nanofluid as coolant can decrease optimal total area of TEMs compared with EG-W, which will bring significant advantages for the optimization and arrangement of TEMs whether the system space is sufficient or not. Moreover, power output enhancement under Cu-EG nanofluid coolant is larger than that of EG-W coolant due to the increase of hot side heat transfer coefficient of TEMs.

On line monitoring of temperatures of coolant channels by thermal imaging in a laboratory set-up fabricated for the detection of leakage of coolants

Energy Technology Data Exchange (ETDEWEB)

Mukherjee, S; Ghosh, J K [Bhabha Atomic Research Centre, Bombay (India). Radiometallurgy Div.; Patel, R J [Bhabha Atomic Research Centre, Mumbai (India). Refuelling Technology Division

1994-12-31

Leakage from coolant channels in Pressurised Heavy Water Reactors (PHWR) increases the temperatures of the faulty channels. Measurement of temperatures of the coolant channels is, therefore, one way to detect the leaking channel. Thermal imaging technique offers a unique means for this detection providing a fast, non-contact, on-line measurement. An experiment was carried out for the detection of leakage of coolants through the seal plugs of the coolant channels in PHWR using an experimental setup under the simulated conditions of temperature and pressure of the coolant channels inside the reactor and using an infrared imaging system. The experimental details and the observations have been presented. 7 figs.

On line monitoring of temperatures of coolant channels by thermal imaging in a laboratory set-up fabricated for the detection of leakage of coolants

International Nuclear Information System (INIS)

Mukherjee, S.; Ghosh, J.K.; Patel, R.J.

1994-01-01

Leakage from coolant channels in Pressurised Heavy Water Reactors (PHWR) increases the temperatures of the faulty channels. Measurement of temperatures of the coolant channels is, therefore, one way to detect the leaking channel. Thermal imaging technique offers a unique means for this detection providing a fast, non-contact, on-line measurement. An experiment was carried out for the detection of leakage of coolants through the seal plugs of the coolant channels in PHWR using an experimental setup under the simulated conditions of temperature and pressure of the coolant channels inside the reactor and using an infrared imaging system. The experimental details and the observations have been presented. 7 figs

LWR primary coolant pipe rupture test rig

International Nuclear Information System (INIS)

Yoshitoshi, Shyoji

1978-01-01

The rupture test rig for primary coolant pipes is constructed in the Japan Atomic Energy Research Institute to verify the reliability of the primary coolant pipes for both PWRs and BWRs. The planned test items consisted of reaction force test, restraint test, whip test, jet test and continuous release test. A pressure vessel of about 4 m 3 volume, a circulating pump, a pressurizer, a heater, an air cooler and the related instrumentation and control system are included in this test rig. The coolant test condition is 160 kg/cm 2 g, 325 deg C for PWR test, and 70 kg/cm 2 g, saturated water and steam for BWR test, 100 ton of test load for the ruptured pipe bore of 8B Schedule 160, and 20 lit/min. discharge during 20 h for continuous release of coolant. The maximum pit internal pressure was estimated for various pipe diameters and time under the PWR and BWR conditions. The spark rupturing device was adopted for the rupture mechanics in this test rig. The computer PANAFACOM U-300 is used for the data processing. This test rig is expected to operate in 1978 effectively for the improvement of reliability of LWR primary coolant pipes. (Nakai, Y.)

A pulse-radiolysis study of the manganese-containing superoxide dismutase from Bacillus stearothermophilus

International Nuclear Information System (INIS)

McAdam, M.E.; Lavelle, F.; Fox, R.A.; Fielden, E.M.

1977-01-01

The mechanism of catalysis of the manganese-containing superoxide dismutase from Bacillus stearothermophilus has been shown to involve a 'fast cycle' and a 'slow cycle' (McAdam, M.E., Fox, R.A., Lavelle, F., and Fielden, E.M., Biochem. J.; 165:71 (1977)). Further properties of the enzyme are now considered. Pulse-radiolysis studies, under conditions of low substrate concentration to enzyme concentration (i.e. when the fast cycle predominates), showed that enzyme activity decreases as pH increases (6.5 to 10.2). Activity was unaffected by the addition of H 2 O 2 or NaN 3 but slightly decreased by KCN. Both H 2 O 2 and the reducing radical anion CO 2 sup(-.) caused a decrease in A 480 of the native enzyme. The rate of the fast catalytic cycle was independent of temperature (5 to 55 0 C), and as temperature increased the slow catalytic cycle became relatively more important. Arrhenius parameters of the rate constants were estimated. The possible identity of the various forms of the enzyme is considered. (author)

Loss of Coolant Accidents (LOCA): Study of CAREM Reactor Response

International Nuclear Information System (INIS)

Gonzalez, Jose; Gimenez, Marcelo

2000-01-01

We analyzed the neutronic and thermohydraulic response of CAREM25 reactor and the safety systems involved in a Loss Of Coolant Accident (LOCA).This parametric analysis considers several break diameters (1/2inch, 3/4inch, 1inch, 1.1/2inch and 2inches) in the vapor zone of the Reactor Pressure Vessel.For each accidental sequence, the successful operation of the following safety systems is modeled: Second Safety System (SSS), Residual Heat Removal System (RHRS) and Safety Injection System (SIS). Availability of only one module is postulated for each system.On the other hand, the unsuccessful operation of all safety systems is postulated for each accidental sequence.In both cases the First Shutdown System (FSS) actuates, and the loss of Steam Generator secondary flow and Chemical and Control of Volume System (CCVS) unavailability are postulated.Maximum loss of coolant flow, reactor power and time for safety systems operation are analyzed, as well as its set point parameters.We verified that safety systems are dimensioned to satisfy the 48 hours cooling criteria

Apparatus for controlling coolant level in a liquid-metal-cooled nuclear reactor

International Nuclear Information System (INIS)

Jones, R.D.

1978-01-01

A liquid-metal-cooled fast-breeder reactor which has a thermal liner spaced inwardly of the pressure vessel and includes means for passing bypass coolant through the annulus between the thermal liner and the pressure vessel to insulate the pressure vessel from hot outlet coolant includes control ports in the thermal liner a short distance below the normal operating coolant level in the reactor and an overflow nozzle in the pressure vessel below the control ports connected to an overflow line including a portion at an elevation such that overflow coolant flow is established when the coolant level in the reactor is above the top of the coolant ports. When no makeup coolant is added, bypass flow is inwardly through the control ports and there is no overflow; when makeup coolant is being added, coolant flow through the overflow line will maintain the coolant level

Apparatus for controlling coolant level in a liquid-metal-cooled nuclear reactor

Science.gov (United States)

Jones, Robert D.

1978-01-01

A liquid-metal-cooled fast-breeder reactor which has a thermal liner spaced inwardly of the pressure vessel and includes means for passing bypass coolant through the annulus between the thermal liner and the pressure vessel to insulate the pressure vessel from hot outlet coolant includes control ports in the thermal liner a short distance below the normal operating coolant level in the reactor and an overflow nozzle in the pressure vessel below the control ports connected to an overflow line including a portion at an elevation such that overflow coolant flow is established when the coolant level in the reactor is above the top of the coolant ports. When no makeup coolant is added, bypass flow is inwardly through the control ports and there is no overflow; when makeup coolant is being added, coolant flow through the overflow line will maintain the coolant level.

Sodium as a reactor coolant

International Nuclear Information System (INIS)

Cesar, S.B.G.

1989-01-01

This work is related to the use of sodium as a reactor coolant, to the advantages and problems related to its use, its mechanical, thermophysics, eletronical, magnetic and nuclear properties. It is mainly a bibliographic review, with the aim of gathering the necessary information to persons initiating in the study of sodium and also as reference source. (author) [pt

Ion beam pulse radiolysis system at HIMAC

Energy Technology Data Exchange (ETDEWEB)

Chitose, N; Katsumura, Y; Domae, M; Ishigure, K [Tokyo Univ. (Japan); Murakami, T

1997-03-01

An ion beam pulse radiolysis system has been constructed at HIMAC facility. Ion beam of 24MeV He{sup 2+} with the duration longer than 1 {mu}s is available for irradiation. Three kinds of aqueous solutions, (C{sub 6}H{sub 5}){sub 2}CO, NaHCO{sub 3}, and KSCN, were irradiated and the absorption signals corresponding to (C{sub 6}H{sub 5}){sub 2}CO{sup -}, CO{sub 3}{sup -}, and (SCN){sub 2}{sup -} respectively were observed. Ghost signals which interfere with the measurement are also discussed. (author)

Pulse radiolysis of 6-aminophenalenone ethanolic solutions

International Nuclear Information System (INIS)

Semenova, G.V.; Kartasheva, L.I.; Ryl'kov, V.V.; Pikaev, A.K.

1986-01-01

Intermediates of 6-aminophenalenone radiolytic transformations in ethanol are investigated using pulse radiolysis method (5 and 8 MeV energy electrons, pulse duration is 2.3 μs and 15 ns respectively). Constants of reaction rate of e s and α-ethanolic radical with dye are measured (they are equal to (9.3±1.0)x10 9 and (1.1±0.2)x10 8 l/(molxs) respectively); optical and kinetic characteristics of products of their interaction are investigated. Mechanism of radiolytic transformations of this dye is proposed

Coolant cleanup system for BWR type reactor

International Nuclear Information System (INIS)

Kinoshita, Shoichiro; Araki, Hidefumi.

1993-01-01

The cleanup system of the present invention removes impurity ions and floating materials accumulated in a reactor during evaporation of coolants in the nuclear reactor. That is, coolants pass pipelines from a pressure vessel using pressure difference between a high pressure in the pressure vessel and a low pressure at the upstream of a condensate filtration/desalting device of a condensate/feed water system as a driving source, during which cations and floating materials are removed in a high temperature filtration/desalting device and coolants flow into the condensate/feedwater system. Impurities containing anions are removed here by the condensates filtration/desalting device. Then, they return to the pressure vessel while pressurized and heated by a condensate pump, a feed water pump and a feed water heater. At least pumps, a heat exchanger for heating, a filtration/desalting device for removing anions and pipelines connecting them used exclusively for the coolant cleanup system are no more necessary. (I.S.)

Reaction of hydrogen atoms produced by radiolysis and photolysis in solid phase at 4 and 77 K

International Nuclear Information System (INIS)

Miyazaki, Tetsuo

1991-01-01

The behavior of H atoms in the solid phase has been reviewed with special attention to comparison of H atoms produced by radiolysis with those produced by photolysis. The paper consists of three parts. I -Production of H atoms: (1) the experimental results which indicate H-atom formation in the radiolysis of solid alkane are summarized; (2) ESR saturation behavior of trapped H atoms depends upon the method of H-atom-production, i.e. photolysis or radiolysis, and upon the initial energy of H atoms in the photolysis. II - Diffusion of H atoms: (1) activation energies for thermally-activated diffusion of H atoms are shown; (2) quantum diffusion of H atoms in solid H 2 is explained in terms of repetition of tunneling reaction H 2 + H → H + H 2 . III -Reaction of H atoms: (1) reactions and trapping processes of hot H atoms have been shown in solid methane and argon by use of hot H atoms with specified initial energy; (2) when H atoms are produced by the radiolysis of solvent alkane or by the photolysis of HI in the alkane mixtures at 77 K, the H atoms react very selectively with solute alkane at low concentration. The selective reaction of the H atom has been found in eight matrices; (3) activation energy for a hydrogen-atom-abstraction reaction by thermal H atoms at low temperatures is less than than several kJ mol -1 because of quantum tunneling. The absolute rate constants for H 2 (D 2 , HD) + H(D) tunneling reactions have been determined experimentally in solid hydrogen at 4.2K; (4) theoretical studies for tunneling reactions H 2 (D 2 ,HD) + H(D) at ultralow temperatures were reviewed. The calculated rate constants were compared with the rate constants obtained experimentally. (author)

Real-time reactor coolant system pressure/temperature limit system

International Nuclear Information System (INIS)

Newton, D.G.; Schemmel, R.R.; Van Scooter, W.E. Jr.

1991-01-01

This patent describes an system, used in controlling the operating of a nuclear reactor coolant system, which automatically calculates and displays allowable reactor coolant system pressure/temperature limits within the nuclear reactor coolant system based upon real-time inputs. It comprises: means for producing signals representative of real-time operating parameters of the nuclear reactor cooling system; means for developing pressure and temperature limits relating the real-time operating parameters of the nuclear reactor coolant system, for normal and emergency operation thereof; means for processing the signals representative of real-time operating parameters of the nuclear reactor coolant system to perform calculations of a best estimate of signals, check manual inputs against permissible valves and test data acquisition hardware for validity and over/under range; and means for comparing the representative signals with limits for the real-time operating parameters to produce a signal for a real-time display of the pressure and temperature limits and of the real-time operating parameters use an operator in controlling the operation of the nuclear reactor coolant system

Sloshing of coolant in a seismically isolated reactor

International Nuclear Information System (INIS)

Wu, T.S.; Guildys, J.; Seidensticker, R.W.

1988-01-01

During a seismic event, the liquid coolant inside the reactor vessel has sloshing motion which is a low-frequency phenomenon. In a reactor system incorporated with seismic isolation, the isolation frequency usually is also very low. There is concern on the potential amplification of sloshing motion of the liquid coolant. This study investigates the effects of seismic isolation on the sloshing of liquid coolant inside the reactor vessel of a liquid metal cooled reactor. Based on a synthetic ground motion whose response spectra envelop those specified by the NRC Regulator Guide 1.60, it is found that the maximum sloshing wave height increases from 18 in. to almost 30 in. when the system is seismically isolated. Since higher sloshing wave may introduce severe impact forces and thermal shocks to the reactor closure and other components within the reactor vessel, adequate design considerations should be made either to suppress the wave height or to reduce the effects caused by high waves

Dynamic response of INTOR/NET blankets after coolant tube rupture

International Nuclear Information System (INIS)

Klippel, H.T.

1985-01-01

The dynamic response of different water-cooled liquid Li 17 Pb 83 breeder blanket modules has been calculated to study the potential of these modules in case of coolant tube rupture. Numerical calculations with the code PISCES have been carried out taking into account the fluid-structure interaction and the elasto-plastic behaviour of the structural material. The results show that for inert coolant characteristics the proposed conceptual designs for NET and INTOR have sufficient resistance against coolant tube rupture but when taking into account energy release due to chemical reaction of water with LiPb-alloy up to doubling of the wall thickness has to be envisaged to guarantee structural reliability. (orig.)

Primary coolant recycling device for FBR type reactor

International Nuclear Information System (INIS)

Kanbe, Mitsuru; Tokiwai, Moriyasu

1998-01-01

A primary coolants (liquid sodium) recycling device comprises a plurality of recycling pumps. The recycling pumps are operated while using, as a power source, electric power generated by a thermoelectric power generation system by utilizing heat stored in the coolants. The thermoelectric power generation system comprises a thermo-electric conversion module, heat collecting heat pipes as a high temperature side heat conduction means and heat dissipating pipes as a low temperature side heat conduction means. The heat of coolants is transferred to the surface of the high temperature side of each thermo-electric conversion elements of the thermal power generation system by the heat collecting heat pipes. The heat on the low temperature side of each of the thermo-electric conversion elements is removed by the heat dissipating pipes. Accordingly, temperature difference is caused between both surfaces of the thermo-electric conversion elements. Even upon loss of a main power source due to stoppage of electricity, electric power is generated by utilizing heat of coolants, so that the recycling pumps circulate coolants to cool a reactor core continuously. (I.N.)

Reactor coolant pump seal leakage monitoring

International Nuclear Information System (INIS)

Stevens, D.M.; Spencer, J.W.; Morris, D.J.; James, W.; Shugars, H.G.

1986-01-01

Problems with reactor coolant pump seals have historically accounted for a large percentage of unscheduled outages. Studies performed for the Electric Power Research Institute (EPRI) have shown that the replacement of coolant pump seals has been one of the leading causes of nuclear plant unavailability over the last ten years. Failures of coolant pump seals can lead to primary coolant leakage rates of 200-500 gallons per minute into the reactor building. Airborne activity and high surface contamination levels following these failures require a major cleanup effort and increases the time and personnel exposure required to refurbish the pump seals. One of the problems in assessing seal integrity is the inability to accurately measure seal leakage. Because seal leakage flow is normally very small, it cannot be sensed directly with normal flow instrumentation, but must be inferred from several other temperature and flow measurements. In operating plants the leakage rate has been quantified with a tipping-bucket gauge, a device which indicates when one quart of water has been accumulated. The tipping-bucket gauge has been used for most rainfall-intensity monitoring. The need for a more accurate and less expensive gauge has been addressed. They have developed a drop-counter precipitation sensor has been developed and optimized. The applicability of the drop-counter device to the problem of measuring seal leakage is being investigated. If a review of system specification and known drop-counter performance indicates that this method is feasible for measuring seal leak rates, a drop-counter gauge will be fabricated and tested in the laboratory. If laboratory tests are successful the gauge will be demonstrated in a pump test loop at Ontario Hydro and evaluated under simulated plant conditions. 3 references, 2 figures

Fuel coolant interaction experiment by direct electrical heating method

International Nuclear Information System (INIS)

Takeda, Tsuneo; Hirano, Kenmei

1979-01-01

In the PCM (Power Cooling Mismatch) experiments, the FCI (Fuel Coolant Interaction) test is one of necessary tests in order to predict various phenomena that occur during PCM in the core. A direct electrical heating method is used for the FCI tests for fuel pellet temperature of over 1000 0 C. Therefore, preheating is required before initiating the direct electrical heating. The fuel pin used in the FCI tests is typical LWR fuel element, which is surrounded by coolant water. It is undersirable to heat up the coolant water during preheating of the fuel pin. Therefore, a zirconia (ZrO 2 ) pellet which is similar to a UO 2 pellet in physical and chemical properties is used. Electric property (electric conductivity) of ZrO 2 is particularly suitable for direct electrical heating as in the case of UO 2 . In this experiment, ZrO 2 pellet (melting point 2500 0 C) melting was achieved by use of both preheating and direct electrical heating. Temperature changes of coolant and fuel surface, as well as the pressure change of coolant water, were measured. The molten fuel interacted with the coolant and generated shock waves. A portion of this molten fuel fragmented into small particles during this interaction. The peak pressure of the observed shock wave was about 35 bars. The damaged fuel pin was photographed after disassembly. This report shows the measured coolant pressure changes and the coolant temperature changes, as well as photographs of damaged fuel pin and fuel fragments. (author)

Combined radiolysis/GLC as a tool for the investigation of stabilizing mechanisms

International Nuclear Information System (INIS)

Koch, J.; Eckert, W.R.

1977-01-01

Combined radiolysis/GLC was used to prove the chemical incorporation of lauric acid from cadmium laurate into polyvinyl chloride. The samples were exposed for 10 days to x-rays at a dose rate of 0.345 Mrad/hr

Pulse radiolysis of ethanolic solutions of rhodamine dyes

International Nuclear Information System (INIS)

Kartasheva, L.I.; Kucherenko, E.A.; Kozlov, A.S.; Pikaev, A.K.

1983-01-01

The primary products of radiolytical transformations of rhodamine 6G, rhodamine B, rhodamine 3B and rhodamine 110 in ethanolic solutions were studied by pulse radiolysis method under various conditions. It was found that the semireduced form of a dye was the only intermediate product of such transformations in ethanolic solutions of all dyes. It was shown that this species was formed by interaction of the dye with esub(s) - and CH 3 CHOH. The properties of this species were investigated and the rate constants of respective reactions for each dye were determined. It was found that nature and position of a substituent in the molecule of the dye have an effect on the rate of formation of the semi-reduced form. (author)

Radiolysis of 2-[{sup 18}F]fluoro-2-deoxy-D-glucose ([{sup 18}F]FDG) and the role of ethanol and radioactive concentration

Energy Technology Data Exchange (ETDEWEB)

Jacobson, Mark S. [Division of Nuclear Medicine, Mayo Clinic, Rochester, MN (United States)], E-mail: jacobson.mark17@mayo.edu; Dankwart, Heather R. [Division of Nuclear Medicine, Mayo Clinic, Rochester, MN (United States); Mahoney, Douglas W. [Division of Biostatistics, Mayo Clinic, Rochester, MN (United States)

2009-06-15

Radiolysis is the process by which radioactively labeled compounds degrade. Many positron emission tomography (PET) radiopharmaceuticals produced with high radioactive concentrations and specific activities exhibit low radiochemical purity because of radiolysis. Little data exist that describe the radiolytic decomposition of 2-[{sup 18}F]fluoro-2-deoxy-D-glucose ([{sup 18}F]FDG). The objective of our study was to profile the degradation of [{sup 18}F]FDG at various radioactive concentrations by measuring radiochemical purity at different time intervals and to study the effects of ethanol, a well-known reductant stabilizer of [{sup 18}F]FDG preparations.

Solid state radiolysis of amino acids in an astrochemical perspective

International Nuclear Information System (INIS)

Cataldo, Franco; Angelini, Giancarlo; Iglesias-Groth, Susana; Manchado, Arturo

2011-01-01

The aliphatic amino acids L-alanine and L-leucine and the aromatic amino acids L-phenylalanine, L-tyrosine and L-tryptophan were irradiated in the solid state to a dose of 3.2 MGy. The degree of decomposition was measured by differential scanning calorimetry (DSC). Furthermore the degree of radioracemization was measured by optical rotatory dispersion (ORD) spectroscopy. From the DSC measurement a radiolysis rate constant k and the half life T 1/2 for each amino acid have been determined and extrapolated to a dose of 14 MGy, which corresponds to the expected total dose delivered by the decay of radionuclides to the organic molecules present in comets and asteroids in 4.6x10 9 years, the age of the Solar System. It is shown that all the amino acids studied can survive a radiation dose of 14 MGy although they are reduced to 1/4-1/5 of their original value they had at the beginning of the history of the Solar System. Consequently, the amount of alanine or leucine found today in the meteorites known as carbonaceous chondrites is just 1/4-1/5 of the amount originally present at the epoch of the formation of the Solar System 4.6x10 9 years ago. Among the amino acids studied, tyrosine shows the highest radiation resistance while tryptophan does not combine its relatively high radiation resistance with an elevated level of radioracemization resistance. Apart from the exception of tryptophan, it is shown that the radiolysis rate constants k of all the amino acids studied are in reasonable agreement with the radioracemization rate constant k rac .

Solid state radiolysis of amino acids in an astrochemical perspective

Energy Technology Data Exchange (ETDEWEB)

Cataldo, Franco, E-mail: franco.cataldo@fastwebnet.i [Istituto Nazionale di Astrofisica-Osservatorio Astrofisica di Catania, Via S. Sofia 78, 95123 Catania (Italy); Lupi Chemical Research, Via Casilina 1626/A, 00133 Rome (Italy); Angelini, Giancarlo [Istituto di Metodologie Chimiche, CNR, Via Salaria Km 29300, 00016 Monterotondo Stazione, Rome (Italy); Iglesias-Groth, Susana [Instituto de Astrofisica de Canarias, Via Lactea s/n, E-38200, La Laguna, Tenerife (Spain); Manchado, Arturo [Instituto de Astrofisica de Canarias, Via Lactea s/n, E-38200, La Laguna, Tenerife (Spain) and CSIC (Spain)

2011-01-15

The aliphatic amino acids L-alanine and L-leucine and the aromatic amino acids L-phenylalanine, L-tyrosine and L-tryptophan were irradiated in the solid state to a dose of 3.2 MGy. The degree of decomposition was measured by differential scanning calorimetry (DSC). Furthermore the degree of radioracemization was measured by optical rotatory dispersion (ORD) spectroscopy. From the DSC measurement a radiolysis rate constant k and the half life T{sub 1/2} for each amino acid have been determined and extrapolated to a dose of 14 MGy, which corresponds to the expected total dose delivered by the decay of radionuclides to the organic molecules present in comets and asteroids in 4.6x10{sup 9} years, the age of the Solar System. It is shown that all the amino acids studied can survive a radiation dose of 14 MGy although they are reduced to 1/4-1/5 of their original value they had at the beginning of the history of the Solar System. Consequently, the amount of alanine or leucine found today in the meteorites known as carbonaceous chondrites is just 1/4-1/5 of the amount originally present at the epoch of the formation of the Solar System 4.6x10{sup 9} years ago. Among the amino acids studied, tyrosine shows the highest radiation resistance while tryptophan does not combine its relatively high radiation resistance with an elevated level of radioracemization resistance. Apart from the exception of tryptophan, it is shown that the radiolysis rate constants k of all the amino acids studied are in reasonable agreement with the radioracemization rate constant k{sub rac}.

Analysis of molten fuel-coolant interaction during a reactivity-initiated accident experiment

International Nuclear Information System (INIS)

El-Genk, M.S.; Hobbins, R.R.

1981-01-01

The results of a reactivity-initiated accident experiment, designated RIA-ST-4, are discussed and analyzed with regard to molten fuel-coolant interaction (MFCI). In this experiment, extensive amounts of molten UO 2 fuel and zircaloy cladding were produced and fragmented upon mixing with the coolant. Coolant pressurization up to 35 MPa and coolant overheating in excess of 940 K occurred after fuel rod failure. The initial coolant conditions were similar to those in boiling water reactors during a hot startup (that is, coolant pressure of 6.45 MPa, coolant temperature of 538 K, and coolant flow rate of 85 cm 3 /s). It is concluded that the high coolant pressure recorded in the RIA-ST-4 experiment was caused by an energetic MFCI and was not due to gas release from the test rod at failure, Zr/water reaction, or to UO 2 fuel vapor pressure. The high coolant temperature indicated the presence of superheated steam, which may have formed during the expansion of the working fluid back to the initial coolant pressure; yet, the thermal-to-mechanical energy conversion ratio is estimated to be only 0.3%

Liquid metal reactor development -Studies on safety measure of LMR coolant

International Nuclear Information System (INIS)

Hwang, Sung Tae; Choi, Yoon Dong; Park, Jin Hoh; Kwon, Sun Kil; Choi, Jong Hyun; Cho, Byung Ryul; Kim, Tae Joon; Kwon, Sang Woon; Jung, Kyung Chae; Kim, Byung Hoh; Hong, Soon Bok; Jung, Ji Yung

1995-07-01

A study on the safety measures of LMR coolant showed the results as follows; 1. LMR coolant safety measure. A. Analysis and improvement of sodium fire code. B. Analysis of sodium fire phenomena. 2. Sodium fire aerosol characteristics. It was carried out conceptual design and basic design for sodium fire facility of medium size composed of sodium supply tank, sodium reactor vessel, sodium fire aerosol filter system and scrubbing column, and drain tank etc. 3. Sodium purification technology. A. Construction of calibration loop. (1) Design of sodium loop for the calibration of the equipment. (2) Construction of sodium loop including test equipments and other components. B. Na-analysis technology. (1) Oxygen concentration determination by the wet method. (2) Cover gas purification preliminary experiment. 4. The characteristics of sodium-water reaction. A. Analysis of the micro and small leak phenomena. (1) Manufacture of the micro-leak test apparatus. B. Analysis of large leak events. (1) Development of preliminary code for analysis of initial spike pressure. (2) Sample calculation and comparison with previous works. C. Development of test facility for large leak event evaluation. (1) Conceptional and basic design for the water and sodium-water test facility. D. Technology development for water leak detection system. (1) Investigations for the characteristics of active acoustic detection system. (2) Testing of the characteristics of hydrogen leak detection system. 171 figs, 29 tabs, 3 refs. (Author)

Liquid metal reactor development -Studies on safety measure of LMR coolant

Energy Technology Data Exchange (ETDEWEB)

Hwang, Sung Tae; Choi, Yoon Dong; Park, Jin Hoh; Kwon, Sun Kil; Choi, Jong Hyun; Cho, Byung Ryul; Kim, Tae Joon; Kwon, Sang Woon; Jung, Kyung Chae; Kim, Byung Hoh; Hong, Soon Bok; Jung, Ji Yung [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

1995-07-01

A study on the safety measures of LMR coolant showed the results as follows; 1. LMR coolant safety measure. A. Analysis and improvement of sodium fire code. B. Analysis of sodium fire phenomena. 2. Sodium fire aerosol characteristics. It was carried out conceptual design and basic design for sodium fire facility of medium size composed of sodium supply tank, sodium reactor vessel, sodium fire aerosol filter system and scrubbing column, and drain tank etc. 3. Sodium purification technology. A. Construction of calibration loop. (1) Design of sodium loop for the calibration of the equipment. (2) Construction of sodium loop including test equipments and other components. B. Na-analysis technology. (1) Oxygen concentration determination by the wet method. (2) Cover gas purification preliminary experiment. 4. The characteristics of sodium-water reaction. A. Analysis of the micro and small leak phenomena. (1) Manufacture of the micro-leak test apparatus. B. Analysis of large leak events. (1) Development of preliminary code for analysis of initial spike pressure. (2) Sample calculation and comparison with previous works. C. Development of test facility for large leak event evaluation. (1) Conceptional and basic design for the water and sodium-water test facility. D. Technology development for water leak detection system. (1) Investigations for the characteristics of active acoustic detection system. (2) Testing of the characteristics of hydrogen leak detection system. 171 figs, 29 tabs, 3 refs. (Author).

The radiolysis of CMPO: effects of acid, metal complexation and alpha vs. gamma radiation

Energy Technology Data Exchange (ETDEWEB)

Bruce J. Mincher; Stephen P. Mezyk; Gary S. Groenewold

2016-05-01

Abstract The group actinide/lanthanide complexing agent octylphenylcarbamoylmethyl phosphine oxide (CMPO) has been examined for its radiation stability by measuring the kinetics of its reactions with free radicals in both the aqueous and organic phases for the free and metal-complexed ligand, identifying its degradation products for both alpha and gamma irradiation, measuring the effects on solvent extraction performance, and measuring the G-values for its degradation under various conditions. This includes the G-values for CMPO in the absence of, and in contact with the acidic aqueous phase, where it is shown that the acidic aqueous phase provides radio-protection for this ligand. It was found that both solvent and metal complexation affect the kinetics of the reaction of the •NO3 radical, a product of HNO3 radiolysis, with CMPO. For example, CMPO complexed with lanthanides has a rate constant for this reaction an order of magnitude higher than for the free ligand, and the reaction for the free ligand in the organic phase is about three times faster than in the aqueous phase. In steady state radiolysis kinetics it was determined that HNO3, although not NO3- anion, provides radio-protection to CMPO, with the G-value for its degradation decreasing with increasing acidity, until it was almost completely suppressed by irradiation in contact with 5 M HNO3. The same degradation products were produced by irradiation with alpha and gamma-sources, except that the relative abundances of these products varied. For example, the product of C-C bond scission was produced only in low amounts for gamma-radiolysis, but it was an important product for samples irradiated with a He ion beam. These results are compared to the new data appearing in the literature on DGA radiolysis, since CMPO and the DGAs both contain the amide functional group.

Radionuclide buildup in BWR [boiling water reactor] reactor coolant recirculation piping

International Nuclear Information System (INIS)

Duce, S.W.; Marley, A.W.; Freeman, A.L.

1989-12-01

Since the spring of 1985, thermoluminescent dosimeter, dose rate, and gamma spectral data have been acquired on the contamination of boiling water reactor primary coolant recirculation systems as part of a Nuclear Regulatory Commission funded study. Data have been gathered for twelve facilities by taking direct measurements and/or obtaining plant and vendor data. The project titled, ''Effectiveness and Safety Aspects of Selected Decontamination Processes'' (October 1983) initially reviewed the application of chemical decontamination processes on primary coolant recirculation system piping. Recontamination of the system following pipe replacement or chemical decontamination was studied as a second thrust of this program. During the course of this study, recontamination measurements were made at eight different commercial boiling water reactors. At four of the reactors the primary coolant recirculation system piping was chemically decontaminated. At the other four the piping was replaced. Vendor data were obtained from two boiling water reactors that had replaced the primary coolant recirculation system piping. Contamination measurements were made at two newly operating boiling water reactors. This report discusses the results of these measurements as they apply to contamination and recontamination of boiling water reactor recirculation piping. 16 refs., 29 figs., 9 tabs

The effects of γ-irradiation on the garlic oil contents in garlic bulbs and the radiolysis of allyl trisulfide

International Nuclear Information System (INIS)

Wei Genshuan, Wang Guanghui; Yang Ruipu; Wu Jilan

1995-01-01

The study of the effects of γ-irradiation on the garlic oil contents in the garlic bulbs and the radiolysis of allyl trisulfide and disulfide were carried out. The content of garlic oil in fresh garlic bulbs treated by gamma ray keeps nearly constant as stored for 10 months long. The main components of the garlic oil are allyl trisulfide (about 60%) and allyl disulfide (about 30%). The G values of radiolysis products of allyl disulfide and trisulfide in ethanol system were determined. The results show that allyl trisulfide is a very effective solvated electron scavenger and can oxidize CH 3 C HOH radical into acetaldehyde, which causes that the formation of 2,3-butanediol is extensively inhibited. (author)

The effects of γ-irradiation on garlic oil content in garlic bulbs and on the radiolysis of allyl trisulfide

International Nuclear Information System (INIS)

Wei Genshuan; Wang Guanghui; Yang Ruipu; Wu Jilan

1996-01-01

A study of the effects of γ-irradiation on garlic oil content in garlic bulbs and on the radiolysis of allyl trisufide and disulfide was carried out. The content of garlic oil in fresh garlic bulbs treated by gamma ray keeps nearly constant when stored for 10 months. The main components of garlic oil are allyl trisulfide (about 60%) and allyl disulfide (about 30%). The G values of radiolysis products of allyl disulfide and trisulfide in ethanol system were determined. The results show that allyl trisulfide is a very effective solvated electron scavenger and can oxidize CH 3 C . HOH radical into acetaldehyde, which means that the formation of 2,3-butanediol is extensively inhibited. (author)

A Preliminary Study of Banana Stem Juice as a Plant-Based Coagulant for Treatment of Spent Coolant Wastewater

Directory of Open Access Journals (Sweden)

Habsah Alwi

2013-01-01

Full Text Available The effectiveness of banana stem juice as a natural coagulant for treatment of spent coolant wastewater was investigated . Three main parameters were studied, namely, chemical oxygen demand (COD, suspended solids (SSs, and turbidity of effluent. Coagulation experiments using jar test were performed with a flocculation system where the effects of spent coolant wastewater pH as well as banana stem juice dosage on coagulation effectiveness were examined. The highest recorded COD, SS, and turbidity removal percentages by banana stem juice were 80.1%, 88.6%, and 98.5%, respectively, observed for effluent at pH 7 using 90 mL dosage. The inulin concentration in the banana stem was examined to be 1.22016 mg/mL. It could be concluded that banana stem juice showed tremendous potential as a natural coagulant for water treatment purposes and could be applied in the pretreatment stage of Malaysian spent coolant wastewater prior to secondary treatment.

Pulse radiolysis of bilirubin in aqueous solution

International Nuclear Information System (INIS)

Barber, D.J.W.; Richards, J.T.

1977-01-01

A pulse radiolysis study of bilirubin, the breakdown product of heme, has been made. In aqueous solution at pH 12, short-lived transient spectra have been obtained for reaction of bilirubin with e/sub aq//sup -/ and OH. Bimolecular rate constants for these reactions have been measured, namely, k/sub BR+e/sub aq//sup -/ equals 9.5 x 10 9 M -1 sec -1 and k/sub BR+OH/ equals 3.45 x 10 9 M -1 sec -1 , and the spectrum of a long-lived product resulting from decay of the bilirubin-OH adduct has been obtained. In addition, solute destruction by OH has been investigated in detail. The transient absorption spectrum for reduction of bilirubin with the H atom at neutral pH has been measured. By measuring the rate of reaction with e/sub aq//sup -/ in the presence of bovine serum albumin (BSA), the mode of binding of bilirubin to this biologically important compound has been studied

Zero waste machine coolant management strategy at Los Alamos National Laboratory

International Nuclear Information System (INIS)

Carlson, B.; Algarra, F.; Wilburn, D.

1998-01-01

Machine coolants are used in machining equipment including lathes, grinders, saws and drills. The purpose of coolants is to wash away machinery debris in the form of metal fines, lubricate, and disperse heat between the part and the machine tool. An effective coolant prolongs tool life and protects against part rejection, commonly due to scoring or scorching. Traditionally, coolants have a very short effective life in the machine, often times being disposed of as frequently as once per week. The cause of coolant degradation is primarily due to the effects of bacteria, which thrive in the organic rich coolant environment. Bacteria in this environment reproduce at a logarithmic rate, destroying the coolant desirable aspects and causing potential worker health risks associated with the use of biocides to control the bacteria. The strategy described in this paper has effectively controlled bacterial activity without the use of biocides, avoided disposal of a hazardous waste, and has extended coolant life indefinitely. The Machine Coolant Management Strategy employed a combination of filtration, heavy lubricating oil removal, and aeration, which maintained the coolant peak performance without the use of biocides. In FY96, the Laboratory generated and disposed of 19,880 kg of coolants from 9 separate sites at a cost of $145K. The single largest generator was the main machine shop producing an average 14,000 kg annually. However, in FY97, the waste generation for the main machine shop dropped to 4,000 kg after the implementation of the zero waste strategy. It is expected that this value will be further reduced in FY98

Pulse radiolysis in model studies toward radiation processing

Science.gov (United States)

Von Sonntag, C.; Bothe, E.; Ulanski, P.; Deeble, D. J.

1995-02-01

Using the pulse radiolysis technique, the OH-radical-induced reactions of poly(vinyl alcohol) PVAL, poly(acrylic acid) PAA, poly(methacrylic acid) PMA, and hyaluronic acid have been investigated in dilute aqueous solution. The reactions of the free-radical intermediates were followed by UV-spectroscopy and low-angle laser light-scattering; the scission of the charged polymers was also monitored by conductometry. For more detailed product studies, model systems such as 2,4-dihydroxypentane (for PVAL) and 2,4-dimethyl glutaric acid (for PAA) was also investigated. With PVA, OH-radicals react predominantly by abstraction of an H-atom in α-position to the hydroxyl group (70%). The observed bimolecular decay rate constant of the PVAL-radicals decreases with time. This has been interpreted as being due to an initially fast decay of proximate radicals and a decrease of the probability of such encounters with time. Intramolecular crosslinking (loop formation) predominates at high doses per pulse. In the presence of O 2, peroxyl radicals are formed which in the case of the α-hydroxyperoxyl radicals can eliminate HO 2-radicals in competition with bimolecular decay processes which lead to a fragmentation of the polymer. In PAA, radicals both in α-position (characterized by an absorption near 300 nm) and in β-position to the carboxylate groups are formed in an approximately 1:2 ratio. The lifetime of the radicals increases with increasing electrolytic dissociation of the polymer. The β-radicals undergo a slow (intra- as well as intermolecular) H-abstraction yielding α-radicals, in competition to crosslinking and scission reactions. In PMA only β-radicals are formed. Their fragmentation has been followed by conductometry. In hyaluronic acid, considerable fragmeentation is observed even in the absence of oxygen which, in fact, has some protective effect against this process. Thus free-radical attack on this important biopolymer makes it especially vulnerable with respect

Radiolysis effects on polyethylene terephtalate

International Nuclear Information System (INIS)

Zaharescu, Traian; Ciuprina, Florin

2005-01-01

The effects of high energy exposure of polyethylene terephtalate, the main electrical insulator for the conduction bars in alternative current generators, is presented. For comparison γ-irradiation was performed in distilled water and air at various doses, up to about 200 kGy. The dependencies of current on time for radiation processed PET sheets allow to depict the variation in the resistivity values as a measure of chemical changes in polyethylene terephtalate macromolecules. The comparison between the evolution of currents in irradiated specimens and spectral analysis bring about a light on the accumulation of radiolysis product in PET matrix. The high energy exposure of PET in air causes an increase of final value of current, while similar experiments in water produces a contrary effect. Some considerations of degradation mechanism are presented

A {open_quotes}zero waste{close_quotes} coolant management strategy

Energy Technology Data Exchange (ETDEWEB)

Kennicott, M.A.

1994-04-01

In June of 1992 the Waste Minimization Program at Rocky Flats Plant (RFP) began a study to determine the best methods of managing water-based industrial metalworking fluids in the plant`s Tool Manufacturing Shop. The shop was faced with the challenge of managing fluids that could no longer be disposed of in the traditional manner, through the plant`s liquid process waste drains, due to a problem they, were having causing in the Liquid Waste Operations Evaporator. The study`s goal was to reduce the waste coolants being generated and to reduce worker exposure to a serious health risk. Results of this study and those of a subsequent study to determine relative compatibilities of various coolants and metals, led to the application of a {open_quotes}zero waste{close_quotes} machine coolant management program. This program is currently saving the generation of 10,000 gallons of liquid waste annually, has eliminated worker exposure to harmful bacteria and biocides, and should result in extended machine tool life, increased product quality, fewer rejected parts, and decreases labor costs.

Minimizing secondary coolant blowdown in HANARO

International Nuclear Information System (INIS)

Park, Y. C.; Woo, J. S.; Ryu, J. S.; Cho, Y. G.; Lim, N. Y.

2000-01-01

There is about 80m 3 /h loss of the secondary cooling water by evaporation, windage and blowdown during the operation of HANARO, 30MW research reactor. The evaporation and the windage is necessary loss to maintain the performance of cooling tower, but the blowdown is artificial lose to get rid of the foreign material and to maintain the quality of the secondary cooling water. Therefore, minimizing the blowdown loss was studied. It was confirmed, through the relation of the number of cycle and the loss rate of secondary coolant, that the number of cycle is saturated to 12 without blowdown because of the windage loss. When the secondary coolant is treated by high Ca-hardness treatment program (the number of cycle > 10) to maintain the number of cycle around 12 without blowdown, only the turbidity exceeds the limit. By adding filtering system it was confirmed, through the relation of turbidity and filtering rate of secondary cooling water, that the turbidity is reduced below the limit (5 deg.) by 2% of filtering rate without blowdown. And it was verified, through the performance test of back-flow filtering unit, that this unit gets rid of foreign material up to 95% of the back-flow and that the water can be reused as coolant. Therefore, the secondary cooling water can be treated by the high Ca-hardness program and filter system without blowdown

ISS Internal Active Thermal Control System (IATCS) Coolant Remediation Project

Science.gov (United States)

Morrison, Russell H.; Holt, Mike

2005-01-01

The IATCS coolant has experienced a number of anomalies in the time since the US Lab was first activated on Flight 5A in February 2001. These have included: 1) a decrease in coolant pH, 2) increases in inorganic carbon, 3) a reduction in phosphate buffer concentration, 4) an increase in dissolved nickel and precipitation of nickel salts, and 5) increases in microbial concentration. These anomalies represent some risk to the system, have been implicated in some hardware failures and are suspect in others. The ISS program has conducted extensive investigations of the causes and effects of these anomalies and has developed a comprehensive program to remediate the coolant chemistry of the on-orbit system as well as provide a robust and compatible coolant solution for the hardware yet to be delivered. The remediation steps include changes in the coolant chemistry specification, development of a suite of new antimicrobial additives, and development of devices for the removal of nickel and phosphate ions from the coolant. This paper presents an overview of the anomalies, their known and suspected system effects, their causes, and the actions being taken to remediate the coolant.

Experimental and numerical study of hydrodynamics of flow-accelerated corrosion in CANDU primary coolant

Energy Technology Data Exchange (ETDEWEB)

Supa-Amornkul, S

2006-07-01

In CANDU-6 reactors, the pressurised high-temperature coolant flows through 380 fuel channels passing horizontally through the core. Each end of a fuel channel has a stainless steel annular end-fitting connected to a carbon steel feeder pipe. The outlet coolant, which is at 310{sup o}C with up to 0.30 steam voidage, turns through 90{sup o} as it passes from flow in the annular end-fitting to pipe flow in the feeder via a Grayloc connector. Since 1996, several CANDU stations reported excessive corrosion of their outlet feeder pipes, especially over the first metre, which consists of single or double bends. Early studies related the attack to the hydrodynamics of the coolant and verified that it was a type of flow-accelerated corrosion (FAC). Local shear stress, which is believed to be one of the important factors contributing to FAC, was approximated in the studies with standard empirical correlations. In order to understand the hydrodynamics of the coolant in the outlet feeders, flow-visualisation studies were done at AECL and UNB. At AECL, the observations were confined to a transparent simulation of an outlet feeder bend but at UNB a full-scale transparent test section simulating the geometry and orientation of an outlet feeder bend with its upstream annular end-fitting was fabricated. The feeder consisted of a 54 mm (inside diameter) acrylic pipe with a 73{sup o} bend, connected to an acrylic simulation of a Grayloc flanged fitting and annular end-fitting. The annular end-fitting consisted of an inner pipe, 110 mm outside diameter, and an outer pipe, 150 mm inside diameter, both 1.907 m long. The tests were performed with water and air at atmospheric pressure and room temperature. The maximum water volumetric flow rate was 0.019 m{sup 3}/s and the volume fraction of air varied from 0.05 to 0.56. In characterizing the flow in the UNB study, particular attention was paid to the patterns at the inside of the bend, where a CFD (computational fluid dynamics) code

Experimental and numerical study of hydrodynamics of flow-accelerated corrosion in CANDU primary coolant

International Nuclear Information System (INIS)

Supa-Amornkul, S.

2006-01-01

In CANDU-6 reactors, the pressurised high-temperature coolant flows through 380 fuel channels passing horizontally through the core. Each end of a fuel channel has a stainless steel annular end-fitting connected to a carbon steel feeder pipe. The outlet coolant, which is at 310 o C with up to 0.30 steam voidage, turns through 90 o as it passes from flow in the annular end-fitting to pipe flow in the feeder via a Grayloc connector. Since 1996, several CANDU stations reported excessive corrosion of their outlet feeder pipes, especially over the first metre, which consists of single or double bends. Early studies related the attack to the hydrodynamics of the coolant and verified that it was a type of flow-accelerated corrosion (FAC). Local shear stress, which is believed to be one of the important factors contributing to FAC, was approximated in the studies with standard empirical correlations. In order to understand the hydrodynamics of the coolant in the outlet feeders, flow-visualisation studies were done at AECL and UNB. At AECL, the observations were confined to a transparent simulation of an outlet feeder bend but at UNB a full-scale transparent test section simulating the geometry and orientation of an outlet feeder bend with its upstream annular end-fitting was fabricated. The feeder consisted of a 54 mm (inside diameter) acrylic pipe with a 73 o bend, connected to an acrylic simulation of a Grayloc flanged fitting and annular end-fitting. The annular end-fitting consisted of an inner pipe, 110 mm outside diameter, and an outer pipe, 150 mm inside diameter, both 1.907 m long. The tests were performed with water and air at atmospheric pressure and room temperature. The maximum water volumetric flow rate was 0.019 m 3 /s and the volume fraction of air varied from 0.05 to 0.56. In characterizing the flow in the UNB study, particular attention was paid to the patterns at the inside of the bend, where a CFD (computational fluid dynamics) code - Fluent 6.1- had

Full reactor coolant system chemical decontamination qualification programs

Energy Technology Data Exchange (ETDEWEB)

Miller, P.E. [Westinghouse Electric Corp., Pittsburgh, PA (United States)

1995-03-01

Corrosion and wear products are found throughout the reactor coolant system (RCS), or primary loop, of a PWR power plant. These products circulate with the primary coolant through the reactor where they may become activated. An oxide layer including these activated products forms on the surfaces of the RCS (including the fuel elements). The amount of radioactivity deposited on the different surface varies and depends primarily on the corrosion rate of the materials concerned, the amount of cobalt in the coolant and the chemistry of the coolant. The oxide layer, commonly called crud, on the surfaces of nuclear plant systems leads to personnel radiation exposure. The level of the radiation fields from the crud increases with time from initial plant startup and typically levels off after 4 to 6 cycles of plant operation. Thereafter, significant personnel radiation exposure may be incurred whenever major maintenance is performed. Personnel exposure is highest during refueling outages when routine maintenance on major plant components, such as steam generators and reactor coolant pumps, is performed. Administrative controls are established at nuclear plants to minimize the exposure incurred by an individual and the plant workers as a whole.

Recent results from the MIT in-core experiments on coolant chemistry

International Nuclear Information System (INIS)

Harling, O.K.; Kohse, G.E.; Cabello, E.C.; Bernard, J.A.

1993-01-01

This paper reports results from an ongoing series of in-core experiments that have been conducted at the 5-MW(thermal) MIT Research Reactor (MITR-II) for optimizing coolant chemistries in light water reactors. Four experiments are in progress, including a pressurized coolant chemistry loop (PCCL), a boiling coolant chemistry loop (BCCL), a facility for the study of irradiation-assisted stress-corrosion cracking, and one for the evaluation of in situ sensors for the monitoring of crack propagation in metal (SENSOR). The first two have now been fully operational for several years. The latter two are scheduled to begin regular operation later this year

Nuclear reactor of pressurized liquid coolant type

International Nuclear Information System (INIS)

Costes, D.

1976-01-01

The reactor comprises a vertical concrete pressure vessel, a bell-housing having an open lower end and disposed coaxially with the interior of the pressure vessel so as to delimit therewith a space filled with gas under pressure for the thermal insulation of the internal vessel wall, a pressurizing device for putting the coolant under pressure within the bell-housing and comprising a volume of control gas in contact with a large free surface of coolant in order that an appreciable variation in volume of liquid displaced within the coolant circuit inside the bell-housing should correspond to a small variation in pressure of the control gas. 9 claims, 3 drawing figures

Radiolysis of Ca14CO3

International Nuclear Information System (INIS)

Sanchez, M.G.A.

1986-01-01

The partition-ion exclusion chromatography is evaluated to analyse non-ionic organic compounds obtained from radiolysis of high specific activity Ca 14 CO 3 . The Ca 14 CO 3 was irradiated by β - decay of carbon-14 or by γ rays from a cobalt-60 source. The crystals were dissolved for qualitative and quantitative analysis of the radiolytic products. Formic and oxalic acids were produced in high yields. Glyoxylic, acetic and glycolic acids, formaldehyde and methanol were produced in low yields. Quantitative determination was carried out by liquid scintillation spectroscopy and the chemical yields (G-values) were calculated for the products. Mechanisms of product formation are proposed based on thermal annealing experiments. (Author) [pt

Steam as turbine blade coolant: Experimental data generation

Energy Technology Data Exchange (ETDEWEB)

Wilmsen, B.; Engeda, A.; Lloyd, J.R. [Michigan State Univ., East Lansing, MI (United States)

1995-10-01

Steam as a coolant is a possible option to cool blades in high temperature gas turbines. However, to quantify steam as a coolant, there exists practically no experimental data. This work deals with an attempt to generate such data and with the design of an experimental setup used for the purpose. Initially, in order to guide the direction of experiments, a preliminary theoretical and empirical prediction of the expected experimental data is performed and is presented here. This initial analysis also compares the coolant properties of steam and air.

Radiolysis of D(+)-carnitine by 60Co-γ-radiation and formation of L(+)-β-methylcholine

International Nuclear Information System (INIS)

Loester, Heinz; Strack, Erich; Seim, Hermann

1986-01-01

The radiolysis of D(+)-carnitine by 60 Co-γ-radiation was examined to obtain optically active β-methylcholine. It was found that the radiolysis leads to a number of trimethylammonium bases but to no other betaines. (+)-β-Methylcholine and acetonyltrimethylammonium could be identified by means of common analytical methods. The amounts of methylamines formed by irradiation were very small. Racemization of the D(+)-carnitine did not occur during irradiation, L(-)-carnitine was not found when an enzymatical determination method was used. The fact that (+)-β-methylcholine was formed from D(+)-carnitine is pharmacologically important, because acetyl-L(+)-β-methylcholine has a strong interaction with muscarinic receptors. (author)

Effects of dissolved species on radiolysis of diluted seawater

International Nuclear Information System (INIS)

Hata, Kuniki; Hanawa, Satoshi; Kasahara, Shigeki; Motooka, Takafumi; Tsukada, Takashi; Muroya, Yusa; Yamashita, Shinichi; Katsumura, Yosuke

2014-01-01

Fukushima Daiichi Nuclear Power Plants (NPPs) experienced seawater injection into the cores and fuel pools as an emergent measure after the accident. After the accident, retained water has been continuously desalinized, and subsequently the concentration of chloride ion (Cl"-) has been kept at a lower level these days. These ions in seawater are known to affect water radiolysis, which causes the production of radiolytic products, such as hydrogen peroxide (H_2O_2), molecular hydrogen (H_2) and molecular oxygen (O_2). However, the effects of dissolved ions relating seawater on the production of the stable radiolytic products are not well understood in the diluted seawater. To understand of the production behavior in diluted seawater under radiation, radiolysis calculations were carried out. Production of H_2 is effectively suppressed by diluting by up to vol10%. The concentrations of oxidants (H_2O_2 and O_2) are also suppressed by dilution of dissolved species. The effect of oxidants on corrosion of materials is thought to be low when the seawater was diluted by less than 1 vol% by water. It is also shown that deaeration is one of the effective measure to suppress the concentrations of oxidants at a lower level for any dilution conditions. (author)

Natural convection heat transfer characteristics of the molten metal pool with solidification by boiling coolant

Energy Technology Data Exchange (ETDEWEB)

Cho, Jae Seon; Suh, Kune Yull; Chung, Chang Hyun [Seoul National University, Seoul (Korea, Republic of); Paark, Rae Joon; Kim, Sang Baik [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

1998-12-31

This paper presents results of experimental studies on the heat transfer and solidification of the molten metal pool with overlying coolant with boiling. The metal pool is heated from the bottom surface and coolant is injected onto the molten metal pool. Ad a result, the crust, which is a solidified layer, may form at the top of the molten metal pool. Heat transfer is accomplished by a conjugate mechanism, which consists of the natural convection of the molten metal pool, the conduction in the crust layer and the convective boiling heat transfer in the coolant. This work examines the crust formation and the heat transfer rate on the molten metal pool with boiling coolant. The simulant molten pool material is tin (Sn) with the melting temperature of 232 deg C. Demineralized water is used as the working coolant. The crust layer thickness was ostensibly varied by the heated bottom surface temperature of the test section, but not much affected by the coolant injection rate. The correlation between the Nusselt number and the Rayleigh number in the molten metal pool region of this study is compared against the crust formation experiment without coolant boiling and the literature correlations. The present experimental results are higher than those from the experiment without coolant boiling, but show general agreement with the Eckert correlation, with some deviations in the high and low ends of the Rayleigh number. This discrepancy is currently attributed to concurrent rapid boiling of the coolant on top of the metal layer. 10 refs., 4 figs., 1 tab. (Author)

Natural convection heat transfer characteristics of the molten metal pool with solidification by boiling coolant

Energy Technology Data Exchange (ETDEWEB)

Cho, Jae Seon; Suh, Kune Yull; Chung, Chang Hyun [Seoul National University, Seoul (Korea, Republic of); Paark, Rae Joon; Kim, Sang Baik [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

1997-12-31

This paper presents results of experimental studies on the heat transfer and solidification of the molten metal pool with overlying coolant with boiling. The metal pool is heated from the bottom surface and coolant is injected onto the molten metal pool. Ad a result, the crust, which is a solidified layer, may form at the top of the molten metal pool. Heat transfer is accomplished by a conjugate mechanism, which consists of the natural convection of the molten metal pool, the conduction in the crust layer and the convective boiling heat transfer in the coolant. This work examines the crust formation and the heat transfer rate on the molten metal pool with boiling coolant. The simulant molten pool material is tin (Sn) with the melting temperature of 232 deg C. Demineralized water is used as the working coolant. The crust layer thickness was ostensibly varied by the heated bottom surface temperature of the test section, but not much affected by the coolant injection rate. The correlation between the Nusselt number and the Rayleigh number in the molten metal pool region of this study is compared against the crust formation experiment without coolant boiling and the literature correlations. The present experimental results are higher than those from the experiment without coolant boiling, but show general agreement with the Eckert correlation, with some deviations in the high and low ends of the Rayleigh number. This discrepancy is currently attributed to concurrent rapid boiling of the coolant on top of the metal layer. 10 refs., 4 figs., 1 tab. (Author)

Natural convection heat transfer characteristics of the molten metal pool with solidification by boiling coolant

International Nuclear Information System (INIS)

Cho, Jae Seon; Suh, Kune Yull; Chung, Chang Hyun; Park, Rae Joon; Kim, Sang Baik

1997-01-01

This paper presents results of experimental studies on the heat transfer and solidifcation of the molten metal pool with overlying coolant with boiling. The metal pool is heated from the bottom surface and coolant is injected onto the molten metal pool. As a result, the crust, which is a solidified layer, may form at the top of the molten metal pool. Heat transfer is accomplished by a conjugate mechanism, which consists of the natural convection of the molten metal pool, the conduction in the crust layer and the convective boiling heat transfer in the coolant. This work examines the crust formation and the heat transfer rate on the molten metal pool with boiling coolant. The simulant molten pool material is tin (Sn) with the melting temperature of 232 .deg. C. Demineralized water is used as the working coolant. The crust layer thickness was ostensibly varied by the heated bottom surface temperature of the test section, but not much affected by the coolant injection rate. The correlation between the Nusselt number and the Rayleight number in the molten metal pool region of this study is compared against the crust formation experiment without coolant boiling and the literature correlations. The present experimental results are higher than those from the experiment without coolant boiling, but show general agreement with the Eckert correlation, with some deviations in the high and low ends of the Rayleigh number. This discrepancy is currently attributed to concurrent rapid boiling of the coolant on top of the metal layer

Device for preventing coolant in a reactor from being lost

International Nuclear Information System (INIS)

Maruyama, Hiromi; Matsumoto, Tomoyuki.

1975-01-01

Object: To prevent all of coolant from being lost from the core at the time of failure in rupture of pipe in a recirculation system to cool the core with the coolant remained within the reactor. Structure: A valve, which will be closed when a water level of the coolant within the core is in a level less than a predetermined level, is provided on a recirculating water outlet nozzle in a pressure vessel to thereby prevent the coolant from being lost when the pipe is broken, thus cooling the core by means of reduced-pressure boiling of coolant remained within the core and boiling due to heat, and restraining core reactivity by means of void produced at that time. (Kamimura, M.)

Gamma-ray radiolysis of methyl iodide in air, in presence of water vapor

International Nuclear Information System (INIS)

Aubert, F.

2002-03-01

This work aims at modelling the processes involved in gamma-radiolysis of methyl iodide diluted in air in presence of steam. It is to determine quantitative and qualitative information, to quantify the importance of the organic iodides destruction in case of a nuclear reactor accident. The main data for radiochemistry and iodine compounds (I x O y and INO x ) formation were reviewed and analysed. Literature data about air products radiolysis reactivity towards I 2 and CH 3 I were used to develop a mechanistic model for methyl iodide destruction in the gas phase under gamma irradiation. An ab initio study was realised for a better understanding of atomic nitrogen ( 4 S and 2 D) reactivity towards CH 3 I. The model was tested on the available experimental data and constitute a way to investigate the main processus involved in methyl iodide destruction. For the low CH 3 I concentrations, about 10 -7 - 10 -8 mol.dm -3 , N and e - are mainly responsible for the destruction. I 2 O 4 (highest iodine oxide in the model) and IONO 2 are the main resulting iodinated' compounds. (author)

Assessment of Loss-of-Coolant Effect on Pressurized Heavy Water Reactors

International Nuclear Information System (INIS)

Kim, Won Young; Park, Joo Hwan; Kim, Bong Ghi

2009-01-01

A CANDU reactor is a heavy-water-moderated, natural uranium fuelled reactor with a pressure tube. The reactor contains a horizontal cylindrical vessel (calandria) and each pressure tube is isolated from the heavy-water moderator in a calandria. This allows the moderator system to be operated of a high-pressure and of a high-temperature coolant in pressure tube. This causes the pressurized liquid coolant in the channel to void and therefore give rise to a reactivity transient in the event of a break or fault in the coolant circuit. In particular, all CANDU reactors are well known to have a positive void reactivity coefficient and thus this phenomenon may lead to a positive feedback, which can cause a large power pulse. We assess the loss-of-coolant effect by coolant void reactivity versus fuel burnup, four factor parameters for fresh fuel and equilibrium fuel, reactivity change due to the change of coolant density and reactivity change in the case of half- and full-core coolant

Pulse radiolysis of water by energetic heavy ion

International Nuclear Information System (INIS)

Taguchi, M.; Sugo, Y.; Iwamatsu, K.; Yamaguchi, M.; Katsumura, Y.

2011-01-01

Complete text of publication follows. Water radiolysis is a fundamental process governing radiation effects in various aspects. Degree of water molecule decomposition depends on the type and LET (Linear Energy Transfer) value of radiations. However, the degradation of water molecules by α-particle has not been clearly understood. In this study, we aimed to clarify the reaction behavior of the groundwater induced by of α-particles from high-level radioactive waste (HLW) in the geological disposal environment. α-radiolysis of water was investigated by use of high energy helium ions accelerated by the AVF cyclotron in TIARA facility, JAEA/Takasaki. The pulsed He ion irradiation technique and online time resolved absorbance measurement system was investigated for direct observation of chemical reactions of transient species produced by irradiations. Hydroxyl (OH) radical is the most important species for reactions in aqueous samples because of its high reactivity and formation yield. NaCl was selected as a probe reagent for the OH radical produced by the irradiation with He ion, and dissolved in pure water. Because 50 MeV He ion has the penetration range at 1.5 mm in water, the sample cell has the thickness of 2 mm, and 50 μm glass windows on the top and bottom for preventing energy loss of the incident ions and measuring the absorbance. The transient absorbance was recorded for the aqueous NaCl solutions using semiconductor LASER diode at 375 nm as a probe light source. ClOH - was formed by the reaction of the OH radical with Cl - . The absorbance of ClOH - increased within the irradiation pulse width, and then decreased gradually. The formation yield of ClOH - which was estimated from the peak absorbance value, increased with the solute concentration. Precise analyses of chemical reactions occurred in track will be discussed at the presentation. This study is a part of the project on geological disposal funded by the Ministry of Economy, Trade and Industry, Japan

Study of the radiolysis of tetracycline hydrochloride in powder form, in aqueous solutions and in benzyl alcohol, at 77K, by electron paramagnetic resonance spectroscopy

International Nuclear Information System (INIS)

Guedes, S.M.L.

1984-01-01

The radiolysis of tetracycline hydrochloride in powder form, dissolved in benzyl alcohol and in acid, neutral and alkaline aerated aqueous solutions at 77K is studied by electron paramagnetic resonance spectroscopy. Mechanisms of reactions that occur in the radiolysis of these systems are proposed and some aspects of the reactions that occurs with electrons and with hydrogen atoms at 77K are investigated, since tetracycline hydrochloride captures both paramagnetic species. Also discussed is the influence of some factors in the migration of these species at 77K, such as: the position of solutes, the crystalline structure of the solvent, the kinetic energy of the species and the angle of incidence in the channeling. The rate constants for the reaction between the electron and physical and chemical traps which are present in the alkaline aerated aqueous solutions, at 77k, are calculated. The values found are, respectively: k=9.6 x 10 15 1 mol -1 s -1 and k= 1.8 x 10 10 1 mol -1 s -1 . (Author) [pt

Coolant material effect on the heat transfer rates of the molten metal pool with solidification

International Nuclear Information System (INIS)

Cho, Jae Seon; Suh, Kune Y.; Chung, Chang Hyun; Park, Rae Joon; Kim, Sang Baik

1998-01-01

Experimental studies on heat transfer and solidification of the molten metal pool with overlying coolant with boiling were performed. The simulant molten pool material is tin (Sn) with the melting temperature of 232 degree C. Demineralized water and R113 are used as the working coolant. This work examines the crust formation and the heat transfer characteristics of the molten metal pool immersed in the boiling coolant. The Nusselt number and the Rayleigh number in the molten metal pool region of this study are compared between the water coolant case and the R113 coolant case. The experimental results for the water coolant are higher than those for R113. Also, the empirical relationship of the Nusselt number and the Rayleigh number is compared with the literature correlations measured from mercury. The present experimental results are higher than the literature correlations. It is believed that this discrepancy is caused by the effect of the heat loss to the environment on the natural convection heat transfer in the molten pool

Hydrodynamic problems of heavy liquid metal coolants technology in loop-type and mono-block-type reactor installations

International Nuclear Information System (INIS)

Orlov, Yuri I.; Efanov, Alexander D.; Martynov, Pyotr N.; Gulevsky, Valery A.; Papovyants, Albert K.; Levchenko, Yuri D.; Ulyanov, Vladimir V.

2007-01-01

In the report, the influence of hydrodynamics of the loop with heavy liquid metal coolants (Pb and Pb-Bi) on the realization methods and efficiency of the coolant technology for the reactor installations of loop, improved loop and mono-block type of design has been studied. The last two types of installations, as a rule, are characterized by the following features: availability of loop sections with low hydraulic head and low coolant velocities, large squares of coolant free surfaces; absence of stop and regulating valve, auxiliary pumps on the coolant pumping-over lines. Because of the different hydrodynamic conditions in the installation types, the tasks of the coolant technology have specific solutions. The description of the following procedures of coolant technology is given in the report: purification by hydrogen (purification using gas mixture containing hydrogen), regulation of dissolved oxygen concentration in coolant, coolant filtrating, control of dissolved oxygen concentration in coolant. It is shown that change of the loop design made with economic purpose and for improvement of the installation safety cause additional requirements to the procedures and apparatuses of the coolant technology realization

Determination of primary yields in the alpha radiolysis of alkaline water

International Nuclear Information System (INIS)

Auclair, Guy

2001-01-01

This work presents a fundamental study of the radiolysis of water within the framework of the management of nuclear waste. During their storage, the packages of cemented radioactive waste are likely to release molecular hydrogen. Indeed, interstitial water undergoes decomposition under irradiation. This phenomenon is called radiolysis. In order to envisage the impact of H 2 de-gasification on the security of the installations, it is necessary to determine the primary radiolytic yields in the cementing medium (characterised by a pH ranging between 12 and 14), which provides a basic simulations thus allowing us to obtain both the quantities of gas and the pressure in the pore. Such data is currently not available in the literature. Studies were undertaken with a beam of accelerated helium ions in order to reproduce the conditions of irradiation on solutions at pH = 13 in order to determine a first complete series of radiolytic yields.A more complete study was undertaken on the effects of LET and pH on the yield of molecular hydrogen. The results seem to show that the yield of this primary product is little influenced by pH. Such results were in good agreement with those obtained by Monte-Carlo simulations. These studies have shown that, contrary to γ irradiations, the irradiations with α-particles do not lead to the same characteristic times. The extrapolation of this data with respect to the problem of the packaging of nuclear waste is delicate due to the limited amount of results in the literature and also the chemical and physical complexity of the concretes. (author) [fr

Experimental Investigation of Heat Transfer Characteristics of Automobile Radiator using TiO2-Nanofluid Coolant

Science.gov (United States)

Salamon, V.; Senthil kumar, D.; Thirumalini, S.

2017-08-01

The use of nanoparticle dispersed coolants in automobile radiators improves the heat transfer rate and facilitates overall reduction in size of the radiators. In this study, the heat transfer characteristics of water/propylene glycol based TiO2 nanofluid was analyzed experimentally and compared with pure water and water/propylene glycol mixture. Two different concentrations of nanofluids were prepared by adding 0.1 vol. % and 0.3 vol. % of TiO2 nanoparticles into water/propylene glycol mixture (70:30). The experiments were conducted by varying the coolant flow rate between 3 to 6 lit/min for various coolant temperatures (50°C, 60°C, 70°C, and 80°C) to understand the effect of coolant flow rate on heat transfer. The results showed that the Nusselt number of the nanofluid coolant increases with increase in flow rate. At low inlet coolant temperature the water/propylene glycol mixture showed higher heat transfer rate when compared with nanofluid coolant. However at higher operating temperature and higher coolant flow rate, 0.3 vol. % of TiO2 nanofluid enhances the heat transfer rate by 8.5% when compared to base fluids.

Radiolysis of Reactive AZO Dyes in Aqueous Solution

International Nuclear Information System (INIS)

Bagyo, Agustin NM; Winarti-Andayani; Hendig-Winarno; Ermin-Katrin; Soebianto, Yanti S

2004-01-01

The effects of radiation on aerated reactive dye solutions i.e Cibacron Violet, Cibacron Orange and Cibacron Yellow solutions have been studied. Parameters analysis were the change of pH after radiation, the change of absorption, degradation products and effects of pH on the radiolysis. The uv-vis absorption of solutions were observed before and after irradiation. pH variation was done from pHs 3, 5, 7, 9 and 12. Irradiation was done at doses of 0, 2, 4, 6, 8 and 10 kGy with dose rate of 5 kGy/h and was determined by a Fricke dosimeter. HPLC with UV detector was used to analyze the degradation products. Oxalic acid was the main degradation product and small amount of succinic acid was also detected. (author)

Core performance of equilibrium fast reactors for different coolant materials and fuel types

International Nuclear Information System (INIS)

Mizutani, Akihiko; Sekimoto, Hiroshi

1998-01-01

Parametric studies with several coolant and fuel materials in the equilibrium state are performed for fast reactors in which natural uranium is fed and all of the actinides are confined. Sodium, sodium-potassium, lead, lead-bismuth and helium coolant materials, and oxide, nitride and metal fuels are employed to compare the neutronic characteristics in the equilibrium state. As to the criticality performance, sodium-potassium shows the best performance among the liquid metal coolants and the metallic fuel indicates the best performance

Mathematical model of the reactor coolant pump

International Nuclear Information System (INIS)

Kozuh, M.

1989-01-01

The mathematical model of reactor coolant pump is described in this paper. It is based on correlations for centrifugal reactor coolant pumps. This code is one of the elements needed for the simulation of the whole NPP primary system. In subroutine developed according to this model we tried in every possible detail to incorporate plant specific data for Krsko NPP. (author)

A pulse-radiolysis study of the manganese-containing superoxide dismutase from Bacillus stearothermophilus

International Nuclear Information System (INIS)

McAdam, M.E.; Fox, R.A.; Lavelle, F.; Fielden, E.M.

1977-01-01

The enzymic reaction mechanism of a manganese-containing superoxide dismutase from Bacillus stearothermophilus was studied by using pulse radiolysis. During catalysis (pH 8.9; 25 0 C), changes occurring in the kinetics of substrate disappearance and in the visible absorption of the enzyme at 480 nm established that the simple two-step mechanism found for copper- and iron-containing superoxide dismutases was not involved. At a low ratio ( 2 sup(-.) was close to exponential, whereas at much higher ratios (> 100) the observed decay was predominantly zero-order. The simplest interpretation of the results invokes a rapid one-electron oxidation-reduction cycle ('the fast cycle') and, concurrently, a slower reaction giving a form of the enzyme that is essentially unreactive towards O 2 sup(-.) but which undergoes a first-order decay to yield fully active native enzyme ('the slow cycle'). The fast cycle involved the native enzyme Esub(A) and a form of the enzyme Esub(B) which could be obtained also be treating the form Esub(A) with H 2 O 2 . Computer calculations made with such a simple model predicted behaviour in excellent agreement with the observed results. (author)

Water radiolysis in a crack tip under gamma ray irradiation

International Nuclear Information System (INIS)

Satoh, Tomonori; Uchida, Shunsuke; Satoh, Yoshiyuki

2002-01-01

Under a non-irradiation condition, oxidant, e.g., O 2 and H 2 O 2 , in a crack tip is supplied from the bulk water. But under irradiation conditions, even if the diffusion of radiolytic species is not sufficient, direct radiolysis in the crack tip causes high concentrations of radiolytic species. As a result of measurements and Monte Carlo calculation of gamma ray energy deposition, it has been confirmed that the energy deposition rate in the gap water is larger than that in the bulk water. The energy absorption rate increases as the gap width decreases and reaches 1.3 times that in the bulk water. In order to evaluate crack propagation rate for irradiation assisted stress corrosion cracking (IASCC) of stainless steel, a water radiolysis model in a crevice is proposed. A larger energy deposition rate in the crevice water produces many more radiolytic species, which causes high oxidant concentrations in spite of enhanced recombination of the species at the crevice inner surface. So, for IASCC evaluation, crevice water chemistry plays an important role to determine the crack propagation rate under irradiation. (authors)

Method of controlling the water quality in nuclear reactors

International Nuclear Information System (INIS)

Ibe, Hidefumi.

1985-01-01

Purpose: To obtain a simple and reliable water quality calculation system and water quality control method based thereon for the entire primary coolant circuits in BWR type reactors. Method: In a method of controlling the water quality of the reactor water by injecting hydrogen into the primary coolant circuits of a nuclear reactor, by utilizing a first linear relationship established between the concentration of oxygen and hydrogen in the main steam system and the concentration of radiolysis products in the reactor core and separators and mixing plenum portions, each of the above-mentioned concentrations is calculated from the concentrations for hydrogen or oxygen. Further, by utilizing the first linear relationship established between the concentrations for the oxygen and hydrogen in the recycling system and the concentration of the radiolysis products in the system from the downcomer to the lower plenum portion, the above-mentioned concentration is calculated from the concentration for oxygen and hydrogen. Then, the hydrogen injection rate into the primary coolant system is determined such that the calculated value takes an aimed value. (Ikeda, J.)

On-Line Coolant Chemistry Analysis

International Nuclear Information System (INIS)

LM Bachman

2006-01-01

Impurities in the gas coolant of the space nuclear power plant (SNPP) can provide valuable indications of problems in the reactor and an overall view of system health. By monitoring the types and amounts of these impurities, much can be implied regarding the status of the reactor plant. However, a preliminary understanding of the expected impurities is important before evaluating prospective detection and monitoring systems. Currently, a spectroscopy system is judged to hold the greatest promise for monitoring the impurities of interest in the coolant because it minimizes the number of entry and exit points to the plant and provides the ability to detect impurities down to the 1 ppm level

A system for cooling electronic elements with an EHD coolant flow

International Nuclear Information System (INIS)

Tanski, M; Kocik, M; Barbucha, R; Garasz, K; Mizeraczyk, J; Kraśniewski, J; Oleksy, M; Hapka, A; Janke, W

2014-01-01

A system for cooling electronic components where the liquid coolant flow is forced with ion-drag type EHD micropumps was tested. For tests we used isopropyl alcohol as the coolant and CSD02060 diodes in TO-220 packages as cooled electronic elements. We have studied thermal characteristics of diodes cooled with EHD flow in the function of a coolant flow rate. The transient thermal impedance of the CSD02060 diode cooled with 1.5 ml/min EHD flow was 7.8°C/W. Similar transient thermal impedance can be achieved by applying to the diode a large RAD-A6405A/150 heat sink. We found out that EHD pumps can be successfully applied for cooling electronic elements.

Determination of radiolysis products in gamma-irradiated multilayer barrier food packaging films containing a middle layer of recycled LDPE

International Nuclear Information System (INIS)

Chytiri, Stavroula; Goulas, Antonios E.; Badeka, Anastasia; Riganakos, Kyriakos A.; Petridis, Dimitrios; Kontominas, Michael G.

2008-01-01

Volatile and non-volatile radiolysis products and sensory changes of five-layer food packaging films have been determined after gamma irradiation (5-60 kGy). Barrier films were based on polyamide (PA) and low-density polyethylene (LDPE). Each film contained a middle buried layer of recycled LDPE or 100% virgin LDPE (control samples). Data showed that a large number of radiolysis products were produced such as hydrocarbons, alcohols, carbonyl compounds, carboxylic acid. These compounds were detected in the food simulant after contact with all films even at the lower absorbed doses of 5 and 10 kGy. The type and concentration of radiolysis products increased progressively with radiation dose, while no new compounds were detected as a result of the presence of recycled LDPE. In addition, irradiation dose appears to influence the sensory properties of table water in contact with films

Selection of an Alternate Biocide for the ISS Internal Thermal Control System Coolant, Phase 2

Science.gov (United States)

Wilson, Mark E.; Cole, Harold; Weir, Natalee; Oehler, Bill; Steele, John; Varsik, Jerry; Lukens, Clark

2004-01-01

The ISS (International Space Station) ITCS (Internal Thermal Control System) includes two internal coolant loops that utilize an aqueous based coolant for heat transfer. A silver salt biocide had previously been utilized as an additive in the coolant formulation to control the growth and proliferation of microorganisms within the coolant loops. Ground-based and in-flight testing demonstrated that the silver salt was rapidly depleted, and did not act as an effective long-term biocide. Efforts to select an optimal alternate biocide for the ITCS coolant application have been underway and are now in the final stages. An extensive evaluation of biocides was conducted to down-select to several candidates for test trials and was reported on previously. Criteria for that down-select included: the need for safe, non-intrusive implementation and operation in a functioning system; the ability to control existing planktonic and biofilm residing microorganisms; a negligible impact on system-wetted materials of construction; and a negligible reactivity with existing coolant additives. Candidate testing to provide data for the selection of an optimal alternate biocide is now in the final stages. That testing has included rapid biocide effectiveness screening using Biolog MT2 plates to determine minimum inhibitory concentration (amount that will inhibit visible growth of microorganisms), time kill studies to determine the exposure time required to completely eliminate organism growth, materials compatibility exposure evaluations, coolant compatibility studies, and bench-top simulated coolant testing. This paper reports the current status of the effort to select an alternate biocide for the ISS ITCS coolant. The results of various test results to select the optimal candidate are presented.

Formation of clusters (ions solvated with products of radiolysis) during irradiation of certain chloralkanes in the condensed phase

International Nuclear Information System (INIS)

Sukhov, F.F.; Karatun, A.A.; Slovokhotova, N.A.

1983-01-01

Using the infrared spectroscopy method, the radiolysis of the 2-chloropropane and 2-chloro-2-methylpropane was investigated in various phase states and in argon matrix at 15 and 77 K. A conclusion is drawn that the reaction of the radiation dehydrochlorination in the chloralkanes investigated occurs under certain conditions in the vicinity of ions, mostly; as this takes place, unique clusters composed of radiolysis products, i.e. ions solvated with complexes of alkane and hydrogen chloride are being formed. (author)

APPLICATION OF MULTIHOLE PRESSURE PROBE FOR RESEARCH OF COOLANT VELOCITY PROFILE IN NUCLEAR REACTOR FUEL ASSEMBLIES

Directory of Open Access Journals (Sweden)

S. M. Dmitriev

2015-01-01

Full Text Available Development of heat and mass transfer intensifiers is a major engineering task in the design of new and modernization of existing fuel assemblies. These devices create lateral mass flow of coolant. Design of intensifiers affects both the coolant mixing and the hydraulic resistance. The aim of this work is to develop a methodology of measuring coolant local velocity in the fuel assembly models with different mixing grids. To solve the problems was manufactured and calibrated multihole pressure probe. The air flow velocity measuring method with multihole pressure probe was used in the experimental studies on the coolant local hydrodynamics in fuel assemblies with mixing grids. Analysis of the coolant lateral velocity vector fields allowed to study the formation of the secondary vortex flows behind the mixing grids, and to determine the basic laws of coolant flow in experimental models. Quantitative data on the coolant flow velocity distribution obtained with a multihole pressure probe make possible to determine the magnitude of the flow lateral velocities in fuel rod gaps, as well as to determine the distance at which damping occurs during mixing. 

Analysis of an Advanced Test Reactor Small-Break Loss-of-Coolant Accident with an Engineered Safety Feature to Automatically Trip the Primary Coolant Pumps

International Nuclear Information System (INIS)

Polkinghorne, Steven T.; Davis, Cliff B.; McCracken, Richard T.

2000-01-01

A new engineered safety feature that automatically trips the primary coolant pumps following a low-pressure reactor scram was recently installed in the Advanced Test Reactor (ATR). The purpose of this engineered safety feature is to prevent the ATR's surge tank, which contains compressed air, from emptying during a small-break loss-of-coolant accident (SBLOCA). If the surge tank were to empty, the air introduced into the primary coolant loop could potentially cause the performance of the primary and/or emergency coolant pumps to degrade, thereby reducing core thermal margins. Safety analysis performed with the RELAP5 thermal-hydraulic code and the SINDA thermal analyzer shows that adequate thermal margins are maintained during an SBLOCA with the new engineered safety feature installed. The analysis also shows that the surge tank will not empty during an SBLOCA even if one of the primary coolant pumps fails to trip

Radiolysis of benzyl alcohol in aqueous solution by external gamma-irradiation

International Nuclear Information System (INIS)

Ikebuchi, Hideharu; Kido, Yasumasa; Urakubo, Goro

1977-01-01

Radiolysis of 0.05% aqueous solution of benzyl alcohol with 60 Co γ-rays ranging from 1 x 10 4 to 7 x 10 5 rad was investigated, in order to presume the change of it contained in radiopharmaceuticals. For both O 2 free and oxygenated solutions, an approximately linear relationship holds between the retaining benzyl alcohol and dose in the range from 1 x 10 5 to 7 x 10 5 rads. The G(-M) values of benzyl alcohol calculated from the relation were 2.34 in the absence and 1.92 in presence of oxygen. In the presence of oxygen, a main product was benzaldehyde and its G value was 0.87. In the absence of oxygen, the main products of the radiolysis were dibenzyl, benzyl phenylcalbinol and hydrobenzoin, which were regarded as the radical-reaction products of PhCH 2 and PhCHOH, and the yield of benzaldehyde was negligible. Irrespective of the presence of oxygen, o- and p-hydroxylated products of benzyl alcohol were found only in small quantity. (auth.)

7-MeV electron LINAC based pulse radiolysis facility at RPCD, BARC

International Nuclear Information System (INIS)

Naik, C.B.; Nadkarni, S.A.; Toley, M.A.; Shinde, S.J.; Naik, P.D.

2017-01-01

7-MeV electron LINAC based pulse radiolysis facility is operational in Chemistry Group of BARC since 1986. The Accelerator is housed in B-132 room in basement of Modular Labs. BARC Accelerator was procured from Radiation Dynamics Inc. UK and its detection system was indigenously developed

Multi-Scale Modelling of the Gamma Radiolysis of Nitrate Solutions

OpenAIRE

Horne, Gregory; Donoclift, Thomas; Sims, Howard E.; M. Orr, Robin; Pimblott, Simon

2016-01-01

A multi-scale modelling approach has been developed for the extended timescale long-term radiolysis of aqueous systems. The approach uses a combination of stochastic track structure and track chemistry as well as deterministic homogeneous chemistry techniques and involves four key stages; radiation track structure simulation, the subsequent physicochemical processes, nonhomogeneous diffusion-reaction kinetic evolution, and homogeneous bulk chemistry modelling. The first three components model...

Fuel-Coolant Interactions: Visualization and Mixing Measurements

International Nuclear Information System (INIS)

Loewen, Eric P.; Bonazza, Riccardo; Corradini, Michael L.; Johannesen, Robert E.

2002-01-01

Dynamic X-ray imaging of fuel-coolant interactions (FCI), including quantitative measurement of fuel-coolant volume fractions and length scales, has been accomplished with a novel imaging system at the Nuclear Safety Research Center at the University of Wisconsin, Madison. The imaging system consists of visible-light high-speed digital video, low-energy X-ray digital imaging, and high-energy X-ray digital imaging subsystems. The data provide information concerning the melt jet velocity, melt jet configuration, melt volume fractions, void fractions, and spatial and temporal quantification of premixing length scales for a model fuel-coolant system of molten lead poured into a water pool (fuel temperatures 500 to 1000 K; jet diameters 10 to 30 mm; coolant temperatures 20 to 90 deg. C). Overall results indicate that the FCI has three general regions of behavior, with the high fuel-coolant temperature region similar to what might be expected under severe accident conditions. It was observed that the melt jet leading edge has the highest void fraction and readily fragments into discrete masses, which then subsequently subdivide into smaller masses of length scales <10 mm. The intact jet penetrates <3 to 5 jet length/jet diameter before this breakup occurs into discrete masses, which continue to subdivide. Hydrodynamic instabilities can be visually identified at the leading edge and along the jet column with an interfacial region that consists of melt, vapor, and water. This interface region was observed to grow in size as the water pool temperature was increased, indicating mixing enhancement by boiling processes

Radiolysis of pyridoxine (vitamin B6) in aqueous solution under different conditions

International Nuclear Information System (INIS)

Albarran, Guadalupe; Ramirez-Cahero, Fernando; Aliev, Roustam

2008-01-01

Aqueous solutions of pyridoxine (1 mM) without or with additive of K 3 [Fe(CN) 6 ] (2.5 mM) were gamma-irradiated at different doses and dose rate of 2.16 kGy/h in the absence of air, in the presence of air or by their saturation with N 2 O. The radiolytic products were analyzed with HPLC, mass spectrometry and UV spectroscopy. 2,4,5-Trihydroxymethyl-3-pyridinol, pyridoxal, isopyridoxal and 6-hydroxypyridoxine were formed by radiolysis in the absence of K 3 [Fe(CN) 6 ], and their concentrations were much higher in samples saturated with N 2 O. Pyridoxi-3,6-quinone was found by radiolysis under all the above-mentioned conditions but only in the presence of K 3 [Fe(CN) 6 ]. Besides, the pyridoxal formation increased in the presence of this oxidizing agent. G values of pyridoxal formation and pyridoxine degradation were quantified. Some details of the radiolytic product formation were discussed

Evaluation of Coolant Injection Procedure in the Severe Accident Management Strategy of APR1400

International Nuclear Information System (INIS)

Cho, Yongjin; Lim, Kukhee; Song, Sungchu; Lee, Sukho; Hwang, Taesuk

2013-01-01

A coolant injection strategy in the severe accident management guideline (SAMG) of APR1400 relates to immediate coolant injection into RCS (Reactor Coolant System) or injection following the recovery of secondary coolant inventory. This strategy could play important role in accident mitigation and radiological consequences. In this study, appropriateness of the strategy was evaluated using MELCOR1.8.6 and several sensitivity studies of the key parameters were performed. Analysis for APR1400 using MELCOR 1.8.6 was performed to evaluate the effectiveness of accident management strategies and the following conclusions were identified. Sequential operation of secondary and RCS injection may not be the best strategy and the simultaneous injection of secondary and RCS injection could be more preferable. At least, the RCS injection should start before complete drainage of water in the safety injection tank using mobile pumps. In this study, the effectiveness of timing of operator action has been examined and the amount of injection flowrate needs to be studied in the future

The installation welding of pressure water reactor coolant piping

International Nuclear Information System (INIS)

Deng Feng

2010-01-01

Large pressure water reactor nuclear power plants are constructing in our country. There are three symmetry standard loops in reactor coolant system. Each loop possesses a steam generator and a primary poop, in which one of the loops is equipped with a pressurizer. These components are connected with reactor pressure vessel by installation welding of the coolant piping. The integrity of reactor coolant pressure boundary is the second barrier to protect the radioactive substance from release to outside, so the safe operation of nuclear power plant is closely related to the quality of coolant piping installation welding. The heavy tube with super low carbon content austenitic stainless steel is selected for coolant piping. This kind of material has good welding behavior, but the poor thermal conductivity, the big liner expansion coefficient and the big welding deformation will cause bigger welding stress. To reduce the welding deformation, to control the dimension precision, to reduce the residual stress and to ensure the welding quality the installation sequence should be properly designed and the welding technology should be properly controlled. (authors)

Favism inducing agents: a pulse radiolysis study of isouramil and convicine

International Nuclear Information System (INIS)

Chevion, M.; Ilan, Y.A.

1980-01-01

Isouramil and covicine, substances implicated in precipitating favic crises in glucose-6-phosphate dehydrogenase deficient individuals, have been studied in N 2 O-saturated aqueous solutions by pulse radiolysis, and the kinetics of the reactions of both substances with OH radicals were determined. The products of these reactions are addition intermediates absorbing above 330 nm. The decay of the intermediate(s) formed in the isouramil reaction is a biphasic one, while the decay of the corresponding intermediate for the convicine reaction is characterized by a single constant. By analogy to uracil, it is suggested that the OH radical is added to the double bond at either positions 5 or 6 of the pyrimidine ring forming two different intermediates. Each of these intermediates loses a molecule of water indicated by the observed biphasic decay reaction. For convicine on the other hand, position 5 is blocked by the O-gucosidic bond and the addition of the OH radical could take place only at position 6. Thus, a single intermediate is formed and its decay is a single-phase one. It has been shown that although free radicals could not be detected in the course of the reactions between isouramil and oxygen or with cellular components by electron paramagnetic resonance, isouramil can participate in a uni-electron transfer reacton and can form relatively stable intermediates. Thus, it is speculated that in the red blood cells isouramil could give rise to deleterious free radicals

Set-up for pulse radiolysis of agressive substances

International Nuclear Information System (INIS)

Kozlowska-Milner, E.; Broszkiewicz, R.; Stanikowski, J.

1975-01-01

A set-up for the pulse radiolysis of aggressive substances with a relatively low consumption of the liquid, tested for anhydrous HNO 3 , has been described. The samples have been irradiated with single pulses of 10 MeV electrons at the linear accelerator type LAE 13-9. The absorption spectra of the irradiated samples (within a range of 300-800 nm) were provided by a xenon lamp. The variations of the voltage from the photomultiplier, coupled with an oscilloscope, were registered with the aid of a Polaroid camera. (T.G.)

Study on B-10 consumption of PWR primary coolant during normal operation

International Nuclear Information System (INIS)

Liang, C.H.

1994-01-01

B-10 consumption under PWR primary coolant conditions has been analyzed. The result indicates its time-dependent change reacting with neutron in the normal operation. In this work, neutron energy assumed to be 4 eV; thermal neutron flux is in the range of 3 x 10 13 to 3 x 10 14 n/sec - cm 2 and the time of cycling of the primary coolant through the RCS is 8 sec. and its retention time in the core region is about 1 sec. Under this condition investigated, B-10 consumption is less than 5% at 3 x 10 13 n/sec - cm 2 thermal neutron flux, and closes to 27% at 3 x 10 14 n/sec - cm 2 by calculation at the 16th month of continuous operation. The effect of B-10 consumption on PWR primary water chemistry is also investigated. (author). 1 fig., 2 tabs., 4 refs

γ-Irradiation-induced radiolysis of inulin in aqueous solutions

International Nuclear Information System (INIS)

Tsyba, I.A.; Revina, A.A.; Shostenko, A.G.

1997-01-01

Radiochemical transformations of inulin in aqueous solutions, in air, in the presence of inert gases, helium, nitrogen and in nitrous oxide exposed to various doses of 60 Co γ-irradiation were investigated. It was shown that interactions in inulin with OH radicals are principally responsible for radiolytic decomposition of inulin. The data on radiolysis of more simple model systems were used to make available decomposition spectra of γ-irradiated aerated aqueous solution of inulin. 9 refs., 6 figs