05 Nuclear fuels (scientific, technical)

03/02236 CTP method - diagnostic method for control of cooling tower operation Novak, M. <‘I (il. I’GR I’~,lr~r~7ecl1. 2003, 83. (i/2), hl 67 Optimal operation of cooling towers of thermal systems, such as fossil- fired power plants. nuclear power plants, heating plants, thermal systems in process and petrochemical industry, significantly raises the efficiency of the entire systems. With the reconstruction of cooling towers and introduction of new technologies significant economic and ecological profits could be expected. The increased system efficiency after cooling tower reconstruction is estimated from 2-5%. what is an enormous amount of energy and money saving considering the output power of such systems. Within the frame of the EU Copernicus Project ‘GCTEBAMA‘. a modification of the described method was performed.

03/02237 Development of carbon sheet pump for control of hydrogen recycling in the GAMMA 10 tandem mirror Ishimoto. Y. ~‘1 (I/. I;‘r,sio,t Engirtrcrin~ and &s;gn. 2003. 65. (3). 429 432. The pumping characteristic of carbon sheet pump (CSP) under the condition of high heat and particle load (several MW/m’ and 2.5x IO*’ H/m- at the beam centre, respectively) is described. Heat transfer calculation is performed for the sake of estimation of the temperature rise. The result shows a high heat conductive C/C material is suitable for this purpose under the condition. Pumping experiments proved that the pumping effect of CSP on neutral beam and recovery of the effect by regeneration experiment by the use of neutral beam injector (21 keV, 20 A) as a high heat and particle source. These results indicate that CSP is applicable under the condition of high heat and particle load.

03102238 Divertor issues on ITER and extrapolation to reactors Kukushkin, A. S. PI ol. Flrriopr Enginewing and Dc,sign, 2003. 65. (3). 355 366. The current status of divertor modelling for ITER is presented, and major physics and technology constraints on the divertor operation are discussed in the paper. Extensive exploration of the operational window of the ITER divertor has lead to the emergence of simple scalings of the divertor plasma parameters with input power and plasma density, which are used here to make an educated guess on the divertor performance in a commercial reactor. The impact of fast transient events (ELMS), causing significant variation of the power loading, on the divertor operation and design in ITER is discussed and their implications for a reactor are shown. The issue of tritium co- deposition via hydrocarbons inside the vacuum vessel and in the pumping ducts is considered for ITER and projected to a reactor.

03102239 Effect of uncompensated SPN detector cables on neutron noise signals measured in VVER-440 reactors Kiss, S. c’f it/. Nuclecrr Engiwerirrg and Desigrz. 2003, 220. (2), 1799192. The Self Powered Neutron Detector (SPND) noise measurements of an operating VVER-440 nuclear reactor are described and character- ized. Signal characteristics may be radically influenced by the geometrical properties of the detector and the cable, and by the measuring arrangement. Simulator is used as a means of studying the structure of those phase spectra that show propagating perturbations measured on uncompensated SPN detectors. The paper presents measurements with detectors of very different sizes (i.e. 20 cm length SPNDs and the 200 cm length compensation cables), where the ratios of the global and local component differ significantly for the different detector sizes. This phenomenon is used up for signal compensation.

03102240 Effects of cross section sets and quadrature orders on neutron fluxes and on secondary 24Na activation rate of a pool type 500 MWe FBR Devan, K. c’f c/l. Anncrls of Nuclear Energy, 2003, 30, (I l), I IXI-1197. In the early stages of shield design for the 500 MWe pool type prototype fast breeder reactor (PFBR), the DLC-37 coupled (lOOn, 21 3) cross-section set, extended to include data for the plutonium isotopes, only was used for the transport calculations. Several limitations were recognized in this set. Two new sets IGC-S2 (lOOn. 21 7) and IGCS3 (175n, 42 y) have been created and validated at IGCAR, based on ENDFIB-VI (5). Comparison of the results of two- dimensional transport calculations using DLC-37, IGCS2 and IGCS3 is presented in this paper, for PFBR. Since the activation of secondary sodium in the Intermediate Heat Exchanger (IHX) depends signifi- cantly but differently on the axial and radial neutron fluxes leaking from the core, 2-D transport calculations with reasonable orders for the anisotropy and angular quadrature are necessary. The effects of anisotropy in the scattering cross-sections and the SN order, on the shield parameters are studied with IGCS2. It is found that 175-group calculations clearly predict the finer details of the neutron spectrum in the sodium pool and would facilitate more accurate shield design of PFBR.

03/02241 transfer

Effects of tube inclination on pool boiling heat

Kang. M.-G \‘i,( /c <II’ /+ei/!r,el.(i!‘, li,zt/ /~<>,I~JJ. 1003. 220. ( I ), 67 XI. Effects of tube inclination angles on nucleate pool boiling heat transfer of w:ttcr at atmospheric pressure have been investigated experimen- rally. Experiments wcrc performed tor bev’cn angles (0, 15, 30. 45. 60, 75, and 90 ) with two tubes ( 12.7 and 19. I mm in diameter) of 540 mm in length. Through the study, it can be concluded that tube inclination gives much change on nucleate pool boiling heat transfer. When the tube is near the horizontal and the vertical positions, the maximum and minimum of heat transfer coefficients arc expected. respectively. The decrease in bubble slug formation on the tube surface and easy liquid access to the surface are thought to bc the causes for the enhanced heat transfer.

03102242 Effects of two-phase liquid-gas flow on the performance of nuclear reactor cooling pumps Poullikkas, A. PI.ORTPS.S it7 ,vu<./eup E~ter;~~, 2003, 42, (1 ). 3 IO. An important aspect of nuclear energy is safety. One of the most severe accidents in nuclear power generation is the loss of coolant, where the re-circulating coolant of the pressurized water reactor may flash into steam. Under such, two-phase flow, conditions the reactor cooling pumps become unable to generate the same head as that of the single- phase flow case. In this work, high-speed video observations were conducted on a nuclear reactor cooling pump, in which, the bubbles motions into the impeller passages were identified.

03/02243 Evaluation of resolved and unresolved resonance range of 232-U Maslov. V. M. ei cr/ -l,l!~o/.\ ,J/ V~CC~/C,O,- finergr, 2003. 30. (I I ). 1155- 1179. A consistent evaluation of 232-U measured database is described. Average resonance parameters are obtained. which reproduce the evaluated total. inelastic scattering scattering, fission and capture cross-sections in the vangc of 0.2-150 keV. This work is performed under the Project Agreement B-404 with the International Science and Technology Center (Moscow).

03/02244 Evolutionary mobile fuel reactors Gandini, A. ct ul Pro~~e’s.v 111 Nuclecrr Energy, 2002, 40, (3-4) 661-671. In this paper, issues relevant to an extended, long-term use of nuclear energy are discussed. In particular, the role of ADS and of the so called evolutionary mobile fuel reactors are considered. A note is presented on specific calculation methods to he adopted for intercomparison and survey analysis of these systems.

03/02245 Fluorination reaction of uranium dioxide in CF4/ OP/NP r.f. plasma Kim, Y. S. er ctl. 4~mcrl.s of ,$‘rrc/rrrr Drrrg,r. 2003. 30, (I I), 1199-1209. Research on the fluorination reaction of UOz in CF4/0fi2 rf (radio- frequency) plasma is carried out under 0.3 Torr total gas pressure. The reaction rates are investigated as functions of the CF4/02/NZ ratio, plasma power, substrate temperature, and exposure time to the plasma. It is found that there exists an optimum CF4/02 ratio of around four for the efficient etching, regardless of the rf power and substrate temperature. The reason that the etching reaction rate reaches the maximum at the optimum gas composition is explained by the optical emission spectroscopy (OES) results showing that fluorine atoms are produced most abundantly in the 80%CF4/20%02 discharge plasma. The highest etching reaction rate at 370°C under 150 W exceeds 1000 mono-layersimin, which is equivalent to 0.4 u mimin. According to the mass spectrometric analysis, the major reaction product turns out to be uranium hexa-fluoride UFr,. Based on the experimental findings, the dominant overall reaction of uranium dioxide in the plasma is determined as UC),+312 CFZ+3/8 Oz=UF,,+3/2 (CO or COa). It is found that this reaction seems to follow a linear kinetics with the activation energy of 12. I kJ/mol. X-ray photoelectron spectroscopy (XPS) analysis confirms UOIFz formation on the surface during the reaction and the two step reaction paths: UOZIUO$+LJF,. Experimental results in the CF4/OL/N2 discharge plasma show that the reaction rate enhances with the addition of the third gas in the binary plasma. The ratio of the reaction rate in the ternary to that in the binary plasma saturates twice as much when the volumetric flow rate of the gas reaches 5’% flow rate of CFJ. It is also found that the reaction rates increase in a linear proportion to the applied plasma power in both the binary and ternary gas discharges and the proportionality in the ternary gas plasma is larger than that in the binary one.

03/02246 Fusion nuclear technology issues studied on the JET facilities LHsser, R. c'f crl. k'usior~ Engineering und Design, 2003. 63-64, 35-46. The Joint European Torus (JET) machine was built from the beginning to perform DT studies and is for the next decade the only machine with DT capability. .JET is thus the tokamak hest suited for studies of

370 Fuel and Energy Abstracts November 2003