[en] These recommendations have been compiled by a working group 'Radiation Damage' which has been set up by the Euratom Working Group for Reactor Dosimetry. The parameters are indicated which must be defined for the characterisation of the neutron dose causing radiation-induced damage in construction materials important for reactor technique. Following an explanation of some theoretical aspects, practical guidelines for neutron metrology on irradiation of graphite and of metals are given. A thorough knowledge of the spectrum of the incident neutrons is required for a proper interpretation of the results of irradiation experiments

[en] Calculations of fluence-to-effective dose conversion coefficients have typically been limited to the standard irradiation geometries of the human body: anterior-to-posterior (AP), posterior-to-anterior (PA), lateral from the right side to the left side (RLAT), lateral from the left side to the right side (LLAT), rotational around the vertical axis (ROT), and isotropic incidence from all directions (ISO). In order to estimate the doses to air crew members exposed to cosmic radiation, the geometrical conditions of irradiation are usually assumed to be isotropic. However, the assumption of isotropic irradiation is in many cases invalid for the high energy component of the radiation field, which is often peaked in the forward direction. Therefore, it was considered useful to extend the calculations of conversion coefficients to other geometries. New sets of conversion coefficients fluence-to-effective dose are presented for the semi-isotropic irradiation of the human body and for the irradiation from the top. Their application to cosmic ray dosimetry is discussed. (author)

[en] The introduction of absorbent materials of neutrons in diffuser media, produces local disturbances of neutronic density. The disturbance depends especially on the nature and size of the absorbent. Approximated equations which relates te disturbance and the distance to the absorbent in the case of thin disks have been drawn. The experimental comprobation has been carried out in two especial cases. In both cases the experimental results are in agreement with the calculated values from these equations. (Author)

[en] In this work a methodology based on Damage mechanics criteria is proposed. This methodology serves for probability assessment of the brittle damage risk for the neutron embrittled vessel elements. The developed methodology is realised in RISK code and has been verified on the base of tough reliability of the pressure vessel, 'Kozloduy' NPP Unit 2. This investigation has been carried out at the given parameters of the possible defects on the vessel's weld 4 taking into account requirements of the western and Russian standards. The obtained values for ductile to brittle transition temperatures, defining the equipment life-time in the presence of maximal defect, are in good consistence with the experimentally determined ones. The analyses of results show that the pressure vessel of 'Kozloduy' NPP Unit 2 has got a high level of reliability from brittle damage risk point of view and that the western standards give more conservative evaluation. On the bases of the results a conclusion is made that the developed methodology enables analysing the influence of possible defects in the neutron embrittled elements on their to reliability and their remained life-time

[en] In order to improve the source characterization of the reactor, especially for recent irradiation experiments in the central irradiation thimble, neutron activation experiments were made on 16 nuclides and the neutron flux spectrum was adjusted using the computer code STAY'SL. The results for the total, thermal and fast neutron flux density at a reactor power of 250 kW are as follows: 2.1x10¹⁷, 6.1x10¹⁶ (E<0.55 eV), 7.6x10¹⁶ (E>0.1 MeV) and 4.0x10¹⁶ (E>1 MeV) m^-2 s^-1, respectively. Calculated damage energy cross sections and gas production rates are presented for selected elements. (orig.)

[en] The aim of this research is to standardize neutron dosimetry measurements and radiation damage calculations to facilitate the comparison of materials effects under irradiation. 2 refs

[en] The damage cross sections of various materials are converted to a data format, which can be used as library for the program SAND-II. The materials available in this library are graphite, stainless steel, aluminium, silicium, chromium, iron, nickel, copper, zirconium, molybdenum, tungsten, vanadium and niobium. A number of these materials have more than one cross section set, originating from different evaluations. Cross sections for some activation reactions, commonly used to determine thermal and fast neutron fluences have been included too. Moreover, also some artificial cross sections are introduced in this library which can be used to derive values for some physical quantities which may characterize neutron spectra

[en] Radiation damage is seen differently by the physicists and the technologists. The physicist wants to understand all physical processes from the first interaction of the irradiating particle with the material leading to the mechanical failure. For technological use it is important to correlate (theoretically, empirically, semiempirically) the mechanical failure with the irradiation source. The basic damage mechanisms are discussed. Radiation damage is directly related to the safety, economy, and design of reactors, either fission or fusion. High energy neutron sources are necessary to study materials and their behaviour for fusion applications. At present there still exists the problem of how damage data obtained in fission reactors can be correlated to useful data for fusion reactor applications. This requires a good dosimetry for the development of correlations. All these radiation damage experiments, their analysis, application and monitoring make use of nuclear data. (author)

[en] Monitor sets provided by VTT Chemical Technology, Finland, were irradiated in 1996 in positions 13 and 23 of the KORPUS facility in Dimitrovgrad, Russia, within the framework of the International Benchmark exercise. The results were reported at the work group meeting in Dimitrovgrad in May 1997 together with DORT calculations performed at VTT Energy. Preliminary spectrum adjustments were also reported. A refined and extended evaluation has now been carried out, including a few minor corrections and modifications, and ^93mNb measurements with LSC. Renewed spectrum adjustments using the LSL-M2 code with corrected input covariances have been performed. The results are presented and evaluated and compared with results of other participants. (author)

[en] After having recalled that the PIN junction detector in silicon has been chosen for its high sensitivity, its linear response to the integrated flow, and its ease of use (small dimensions, no connections under flow), the author describes the practical operation of this detector (used junctions, practical use, used apparatus), discusses its expectable precision (error origins, random errors, systematic errors, calculation of the statistic error due to the influence of random origins, assessment of the global systematic error and of the error due to the linearity defect), reports the calibration of the detectors on a fission flow (calibration method, experimental installation, conversion of measurement results into equivalent fission flow), and the determination of the minimum and maximum measurable flows. The last part summarizes the detector characteristics: basic formulas, precision assessment