[en] Full text: Transmission of experimental neutron data in the computerized exchange format EXFOR has continued at an accelerating pace. During the past year (June 1971 - May 1972) the NNCSC has transmitted to the other three centers containing 113,333 records from 122 experimental works, and has received from the other three centers 3 tapes containing 34,615 records from 132 experimental works. Additional data transmissions and receipts have occurred to meet special demands for data not yet in EXFOR. Translation of data from the older less detailed SCISRS-I file has been done by computer as far as can be done, into 42 tapes of data in an incomplete EXFOR-type format, involving about 1,371,000 records. These are being given first order corrections such as combining duplicate data sets, correcting data that are markedly discrepant, and checking bibliographic entries. To date, 13 of those tapes, involving 290,000 records, have been thus corrected, leaving 243,000 records; these are all the data for the heavy isotopes (Z > 88). These 13 tapes have now been merged into the CSISRS library for our own use, and they will be sent in EXFOR format as special transmissions to the other three Centers. A computerized Bookkeeping System for CSISRS is being developed and and put into operation. Among other features, it should keep track of the type of information requested for retrieval from CSISRS by any individual requestor, and it should be able to retrieve the same type of information from material being added to CSISRS in the future. We hope to use this capability to make routine retrievals of new information relevant to the requests made in the U. S. Compilation of Requests, last published as NCSAC-33. If successful in this, we may then be able to make computerized transmission of U. S. requests to the International Requests List. A meeting of the heads of U. S. Low Energy Nuclear Physics Data Centers was held at Brookhaven in September 1971 to compare problems and approaches in handling such data. Represented were the Nuclear Data Project, Table of Isotopes, Energy Levels of Light Nuclei, Chart of the Nuclides, Charged Particle Information Center, Photonuclear Data Center, Gamma Ray Spectrum Catalogue, and the National Neutron Cross Section Center. Common ground was explored for exchange of basic information. It was evident that computerization was used so differently by these Centers that computerized data would probably not be exchanged among them. Cooperation in literature scanning is possible. Joint efforts to improve the data content of published articles,by stricter editorial standards, were considered to be worthwhile. Brookhaven hosted the Seventh Four-Center Meeting in October 1971. Two meetings of the Cross Section Evaluation Working Group were held, in December 1971 and May 1972. The main business of this group during the past year was the development and testing of ENDF/B-III, the third version of the reference Evaluated Neutron Data File. This new library covers 124 materials - many more (especially fission products) than its predecessor, ENDF/B-II. It also has photon interaction cross sections for 78 materials and photon production cross sections for 12 materials. More important, calculations made for a number of different fast reactors show that the cross sections chosen for ENDF/B-III agree better with integral experiments than did those of its predecessor. The ENDF/B-III files for six materials used as cross-section standards were sent to NDS in April for world-wide user H, ³He, ⁶Li, ¹⁰B, ¹⁹⁷Au, and ²³⁵U. Records of the past two years show that the NNCSC receives typically 27 requests per month for machine retrieval of data: 15 for experimental data, 12 for evaluated data. Many other requests are received and handled on the telephone using listings and other material available at this Center. Analysis of the requests for evaluated data indicates that 44% of them come from U. S. Industry, 22% from U. S. National Laboratories, 16% from U. S. Universities, 8% from U. S. Government agencies, and 10% from abroad. (author)

[en] In any activity, one must start with the determination of its usefulness: in the field of nuclear data, this consists in the compilation of request lists, analogous to the RENDA list, issued in cooperation by the CCDN and the Nuclear Data Center of the N. D. S. At Obninsk, we have a somewhat different approach for our RENDA entries. We do not ask our reactor physicists to formulate their requests for concrete microscopic measurements or to share the requested accuracies between the different needed cross sections, because they are not really specialists in this field. We ask them to formulate their requirements, based on technical and economical considerations, for the tolerable uncertainties on the reactor parameters which are, of course, linked to the uncertainties on nuclear data. In addition, we ask them to give us the sensitivity coefficients for the values of reactor parameters as a function of modifications of the nuclear data. These sensitivity coefficients include all the needed information concerning the reactor in view of the determination of the requirements on nuclear data. The problem of the determination of the set of measurements necessary to obtain the reactor parameters with the required accuracies must, from our point of view be treated mathematically by specialists of the planification theory, working in close connection with specialists of microscopic data measurements and of integral experiments. In order to work out an optimal planing, it is necessary to evaluate the relative costs of the experiments; it is also essential to evaluate correctly the correlations between the uncertainties of the measurements and the estimation of their costs. Moreover, we may know all the information concerning the present accuracy on the measurements of a given type, first of all for a comparative evaluation of the costs of the experiments and, secondly, for drawing conclusions on the possible necessity for more accurate values by comparing the accuracies which have been reached to the accuracies which are desired. The accuracies which have been reached can only be given by an evaluation of the nuclear data; in a similar way, the systematic and unforeseen errors in experimental data generally appear by comparison between results obtained from different techniques. The evaluation activity is then considered as absolutely necessary for the elaboration of the lists of nuclear data needs. In other words, we consider as impossible to deal with RENDA without having a close connection with the evaluation activities. An original aspect of the organization of the works in the Centre can be mentioned: the production of data files in the exchange format is divided by subjects and the person in charge of a particular subject is also responsible for the corresponding evaluation and works in cooperation with the specialists of the measurements and specialists of theoretical interpretation in the same field.

[en] The following report on the activities of the Neutron Data Compilation Centre (CCDN) of the NEA covers the period from June 1971 to May 1972. The main objectives during this period were: - improve response to customers' requests for selective retrievals from the numerical and bibliographic data files; - continuation of the effort to update and correct the experimental files, with assistance from outside visitors; - exchange of experimental data with the other three neutron data centres under the EXFOR agreement; - production and publication of new indices to the experimental and to the evaluated data files; - maintenance of the CINDA master file and performance of the necessary computer operations on behalf of the three European data centres, preparation of the tape from which CINDA 72 was printed, development of a new programme system and of a link between the experimental and bibliographic files in order to make CINDA an index to the experimental data available from the four centres as well as a bibliographic index; - co-operation with IAEA/NDS on the compilation of the first world-wide RENDA list, performance of all the computer operations, hand-over of the RENDA programme system to NDS; - the urgent exchange of disk drives and disk packs in order to provide sufficient external storage capacity for the growing files.

[en] Full text: In view of the unique capabilities of cross section measurements with nuclear explosions interest exists in the Federal Republic of Germany to participate in an ''open shot''. The main area of interest are cross sections of Transuranium Isotopes, which cannot be measured by other techniques. The data are needed for a better prediction of isotope build up in spent reactor fuel elements, what is relevant to reprocessing and waste storage problems. A second field is the production of Transuranium Isotopes for utilization in several applications. A first check resulted in the following request: Isotopes: ²³¹Pa, ²³³Pa, ²⁴¹Am, ²⁴²Am, ²⁴³Am, ²⁴⁴Am, ²⁴²Cm, ²⁴⁴Cm Data: primarily σ_nγ resonance region, supplementary σ_f resonance and fast region. Accuracy: 30% would be a substantial improvement beyond present knowledge. It would be appreciated if a broad international cooperation could be initiated to tackle this large program. The contribution from Germany could consist of performing one or two experiments. Most urgent seem to be the data for ²⁴¹Am and ²⁴²Cm. For ²⁴¹Am both the wheel and the Moxon-Rae detector technique are being considered in order to separate the cross sections of the two isomeric states. (author)

[en] The Photonuclear Data Center is continuing to maintain current with the published literature its data abstract files and at the same time build up a library of selected cross section data in digitized form. This library now contains data for over 400 cross section curves measured for 87 different materials covering 47 elements. Within its limited resources the Center is furnishing on request both selected annotated indices and bibliographies covering specific types of data or reactions as well as what it considers to be the best available data for specific cross sections for specific nuclei. Data are primarily furnished on data abstract sheets. As the digitized cross section library is developed, information will also be furnished in digital or large scale graphical form. A listing of new Photonuclear Data Index entries covering the data entered into the Center's files since the publication of NBS Special Publication 322 (Photonuclear Data Index, June 1965-January 1970) will be prepared for distribution to workers in the field at the time of the September 1972 meeting to be held in Sendai, Japan on Nuclear Structure Studies using Electron Scattering and Photoreactions. A complete, updated cumulative index to the published data for the field is scheduled for publication at the time of the Asilomar, California, International Conference on Photonuclear Reactions and Applications (March 1973). The plans to evaluate the data in the Center's files and publish a comprehensive, annotated compilation of the best available information on the photonuclear interaction have received a big boost with the assignment of a KAS-NRC, Nuclear Information Research Associate to work with the group for a two-year period starting in September 1972. The objective of the proposed ''atlas'' will be to present, in a uniform format, all of the information relevant to the interaction of photons with nuclei in such a way that it is readily available and useful not only for theoretical and experimental physicists working in the field but also for various applied users of such data in areas of activation analysis, radiation shielding, medical physics, etc.

[en] Full text: At present the nuclear data work is concentrated in preparing a 56 group cross-section set for the computer code EPITHET a lattice calculations code for light and heavy water moderated reactors. The library for this code is being prepared with the help of basic nuclear data received through the courtesy of IAEA and other sources. In particular the point data from the U.K. Nuclear Data File in being used. The library for U-238 has been prepared for the resonance region. For the preparation of this library, Breit Wigner Formulae were used to obtain point cross-sections employing resonance parameters given in BNL-235 and by Schmidt. With 1/S weighting, fine group cross-sections for about 1600 groups were generated and then used for EPITHET calculations upto 906.9 cV. Between 936.9 eV and 3519 eV resonances were treated individually while above 3519 eV resonances were treated as unresolved. Averaging over Porter Thomas distribution for neutron width and Wigner distribution for level spacings was carried out for the effective group cross sections in the unresolved range. For the cress-checking of this library, it is proposed to repeat these calculations using the point data for U-238 from U.K. Nuclear Data File DFN 401 A. For U-235 and Pu-239 energy point data from the U.K. Nuclear Data Files (DFN 66 and 65A respectively) was used. Assuming linear variation between adjacent points and 1/E weighting, fine group cross-sections were obtained and then used in EPITHET. For temperature dependent group cross-sections, the program TEMPO was used to Doppler broaden the point data. The procedure indicated above was repeated with the broadened data. It is also planned to use Th-232 data and Pu-240 (DFN 77A) data from UK file for preparation of the multigroup data. In the thermal energy region it is proposed to get the group cross-sections using a Maxwellian spectrum at 300 deg. K as the weighting factor and point data from U.K. files. Apart from this, the US multigroup library GAM and UK multigroup library WIMS were put in proper form for utilization with our computer codes. Some progress was made in the adaptation of ENDF/B data file obtained from US. In this connection the computer code EC² was broken into several overlays. This was done to accommodate it on a 32k machine. Tho resolved and unresolved resonance part of EC² was commissioned and it was tested against the plutonium-239 and uranium-235 data. (author)

[en] This document contains the Official Minutes of the Fifth Meeting of the International Nuclear Data Committee (INDC) held in Vienna 17-21 July 1972. Reports included in the appendices have been indexed separately.