[en] In fusion power plant divertors a significant portion of the total fusion power is absorbed. In order to achieve a high thermal plant efficiency this power has to be removed at high temperature levels. This calls for innovative designs which differ from those proposed for experimental fusion machines. In this study, evaporation cooling of liquid metals is considered evaluating: (i) a concept based on pool boiling; and (ii) a concept based on the transport of liquid through a capillary layer and evaporation at the surface of this layer. The latter concept employs characteristic features of high heat flux liquid metal heat pipes. Both concepts are characterised by the operation at high temperatures (between 750 and 1200 deg. C, depending on the choice of the liquid metal) but small stresses due to small temperature differences and operating pressures. The second concept is assessed to have the potential of significantly higher heat loads (in space craft applications heat loads of much larger than 10 MW/m² were reached). A conceptional design description is presented; divertor relevant performance limits are estimated and open issues and the required R and D work are briefly addressed

[en] The thermomechanical interaction of solid breeder and beryllium pebble beds with structural material (BSMI) has been identified as a critical issue for solid breeder blanket designs. For example, the expansion of pebble beds restrained by blanket structure exerts stresses on the pebbles as well as the blanket structure wall, which might cause the pebbles to break and jeopardise the blanket operation. However, at elevated temperatures thermal creep will reduce these stresses and might compensate for stress build-up due to irradiation-induced swelling. A significant influence of irradiation on the pebble bed properties is expected. Computationally, the BSMI can be assessed in two ways: (i) by applying appropriate finite element codes combined with the description of modules for the pebble beds. As input, these modules require data on characteristic pebble bed properties determined in different standard-type tests; (ii) by numerical simulations based on a discrete numerical model. Here, the stress profiles are calculated while the effective modulus and bed thermal expansion coefficients are back estimated. In this paper, recent experimental results on thermomechanical pebble bed properties for ceramic breeder (metatitanate and orthosilicate) pebble beds and beryllium pebble beds are presented, including data on the moduli of deformation, thermal creep, inner friction angle, and thermal conductivity of deformed pebble beds. Furthermore, modelling results of the BSMI for simple geometries are reported based both on homogeneous and discrete models and are compared with experimental results

[en] Following the results obtained from the succesful transatlantic flight launched during the summer 1976 from the CNR Milo Base, Sicily, the Laboratorio di Astrofisica Spaziale has started a new program in the hard X-ray astronomy field. It basically consists in the development of high resolution large area Multiwire Proportional Chambers to be employed in long duration balloon flights to study and monitor galactic and extragalactic sources. This note will describe the flight configuration and performances of the HXR80M payload. The experiment is expected to fly during July 1980 from the Milo Base in the framework of the CNR experimental balloon campaign. The note will analyze the main characteristics of the detectors employed, of the data handling electronics and in particular of the hardware and the software of the on-board microprocessor controlled multichannel analyzer. In fact the limitation due to the low bit rate HF link (1.2kbit/s) and the long flight duration (about one week) make imperative the use of an on-board microprocessor system to handle and select in real time the scientific data and to control the housekeeping and the telecommand systems

[en] Thermomechanical performance of the first wall (FW) W/EUROFER sandwich type module is analyzed under DEMO reactor conditions. Engineering heat loads to the FW panels are estimated for steady state operation with the edge localized modes (ELMs). Calculations carried out by MEMOS code show the inhomogeneity of the material temperature due to discrete location of the water cooling tubes embedded into EUROFER. The hot spots are formed in the W armor and EUROFER between the cooling sectors and depend on the distance of their mutual locations. The bending stress due to vertical temperature gradients in W and EUROFER layers is calculated and remains smaller than the ultimate tensile stress for expected temperatures. Calculations show that under the Type I ELMs expected in DEMO the W surface melts at the ELMs peak positions and solidifies between ELMs. There is no temperature difference found between hot and cool spots during ELMs. (paper)

[en] The analysis performed with RELAP5/MOD1/019 code and related to six problems proposed by NEA, should be considered a preliminary step in acquiring sensitivity in the code use; the work also allowed to find some errors present in the code version available at Pisa University and running on an IBM computer. As a general remark the analysis performed by varying the time step limits, evidenced the lack of stability of the code and then the noticeable dependence of output variables trends from the imposed time steps. An intervention of the code developers is then required, also with the aim to implement more appropriate criteria for the choice of time steps; in this sense the possibility to introduce some other variable (apart from volumes average density, already included) to control time step limits should be evaluated. Finally the complexity and the number of information which should be included in the nodalization of an assigned problem suggest the need to establish criteria in order to make easier the comparison among different nodalizations and, in general, their understanding

[en] As a result of a five year development program, a final prototype of a Very Large Area Spectroscopic Proportional Counter (VLASPC), to be employed in space borne payloads, was produced at the Istituto di Astrofisica Spaziale, Frascati. The instrument is the last version of a new generation of Multiwire Spectroscopic Proportional Counters (MWSPC) succesfully employed in many balloon borne flights, devoted to hard X-ray astronomy. The sensitive area of this standard unit is 2700 cm² with an efficiency higher than 10% in the range 15-180 keV (80% at 60 keV). The low cost and weight make this new type of VLASPC competitive with Nal arrays, phoswich and GSPC detectors in terms of achievable scientific results. (orig.)

[en] The HXR80M large-area hard X-ray experiment, to be flown aboard a transatlantic balloon, is described. The detectors are two multiwire spectroscopic proportional counters (MWSPC) with a 2700-sq-cm sensitive area each. The two detectors are filled with an extremely pure xenon-isobutane mixture at high pressure (3-6 atm) in order to obtain good spectral resolution and high efficiency. The onboard data handling is performed by microprocessor-controlled electronics. The scientific aim of the experiment is the survey of the sky belt around the 38th parallel and in particular the observation of faint galactic objects and galactic binary systems in the 15-200 keV range

[en] The second generation of detectors for hard X-ray astronomy essentially requires large area detectors and efficient background discrimination. A conventional scheme is to use an array of NaI scintillator crystals with a large number of photomultipliers, a light collection system and individual guard counters for charged particle rejection. High pressure proportional counters can provide an alternative instrument with comparatively higher performance in terms of effective area and background discrimination at lower cost and weight. A 900 cm² detector, with a thin aluminium window (0.16 g/cm²) and a 4 atm xenon filling has been developed and tested on a balloon flight. (Auth.)

[en] Following the results obtained from the successful transatlantic flight launched during the summer 1976 from the CNR Milo Base, Sicily, the Laboratorio di Astrofisica Spaziale has started a new program in the hard X-ray astronomy field. It basically consists in the development of high resolution large area Multiwire Proportional Chambers to be employed in long duration balloon flights to study and monitor galactic and extragalactic sources. The authors describe the flight configuration and performances of the HXR80M payload. The experiment is expected to fly during July 1980 from the Milo Base in the framework of the CNR experimental balloon campaign. The authors analyze the main characteristics of the detectors employed, of the data handling electronics and in particular of the hardware and the software of the on-board microprocessor controlled multichannel analyzer. In fact the limitation due to the low bit rate HF link (1.2Kbit/s) and the long flight duration (about one week) make imperative the use of an onboard microprocessor system to handle and select in real time the scientific data and to control the housekeeping and the telecommand systems. (Auth.)

[en] In this paper we analyse a sandwich-type blanket configuration of W/EUROFER for DEMO first wall under steady-state normal operation and off-normal conditions, such as vertical displacements and runaway electrons. The heat deposition and consequent erosion of the tungsten armour is modelled under condition of helium cooling of the first wall blanket module and by taking into account the conversion of the magnetic energy stored in the runaway electron current into heat through the ohmic dissipation of the return current induced in the metallic armour structure. It is shown that under steady-state DEMO operation the first wall sandwich type module will tolerate heat loads up to ∼14 MW/m². It will also sustain the off-normal events, apart from the hot vertical displacement events, which will melt the tungsten armour surface