Cross Sections for Transmutation
Measurement of Reaction Cross Sections Leading to Production and Destruction of Radioactive Materials
Tech Area / Field
- FIR-NOT/Nuclear and Other Technical Data/Fission Reactors
3 Approved without Funding
Khlopin Radium Institute, Russia, St Petersburg
Project summaryProblems associated with processing, recovery, transmutation and storage of long-lived radioactive products in the nuclear industry are considered nowadays as essential issues to be addressed. There are several proposals to solving these tasks, which use the available evaluated data for cross sections of nuclear reaction for various nuclides used and produced in nuclear reactors. Among them, the cross sections for radioactive nuclei are of great importance. However, due to the lack of experimental information, the evaluations taken from different national libraries differ strongly. For example, the evaluations for 241Am (n, 2n) 240 Am and 241Am (n, 3n) 239Am cross sections differed from 2 to 100 times. The pioneering experiments carried out recently at the Khlopin Radium Institute in the frame of the ISTC Project #176 narrow essentially the area of the possible scattering of evaluations. This may lead to working out the more reliable conclusions about efficiency of the proposed technology for nuclear waste transmutation and could provide the economy of expenses for building up new experimental set-ups.
The main purpose of the present proposal is to obtain the new experimental information for the radioactive nuclei, which produce the most serious problem at the nuclear waste disposal and transmutation. To some extent, this is a development of the job curried out in the frame of the ISTC Project #176 from 01.03.1995 to 31.05.1997. However, the main objective of the Project #176 was to obtain the reliable information of high quality for the isotopes where other results, not very good though, existed already, in order to provide a possibility of making a more accurate evaluation, which could be changed not very much, for about twenty - thirty percents. The present Proposal is mainly devoted to measurements of cross sections, which never were properly measured, and, as a consequence, the evaluations of those are scattered several times often. An important part of the Proposal is related with the cross section measurement for actinides and other radioactive nuclei. Naturally, the planed experiments will be very complicated and will require development and use different experimental methods and will involve skilled specialists having a rich experience in the radioactive materials treatment. The specially equipped rooms and special materials will be required also. All this is available in the Khlopin Radium Institute.
The next direction of the present Proposal is the continuation of systematic and precise measurement of nuclear reaction cross sections at neutron energy around 14 MeV for comprehensive validation of the International Activation Library FENDL/A-2.0, which was created recently on the base of several national libraries. At present, this is the most complete Library of Activation Data, which includes more then 13000 cross sections in neutron energy range up to 20 MeV. Nevertheless, it needs to be improved. Using well tested methods and high-productive set-ups created in the Project #176 we could produce a large volume of a high quality experimental information for validation of evaluations included in the FENDL/A-2.0 providing a rather low cost of an inpidual measurement.
The third aspect of this Proposal is the improvement of systematics of nuclear reaction cross sections using and developing the newest achievements in this field. Since the immediate measurement of cross sections that should meet the requests of nuclear power engineering is possible to do for a very limited number of those only, and many of such measurements are very difficult and expensive, the enhance of the predictive force of systematics is an important addition to the complicated theoretical calculations because the systematics allow to make the cross section estimation very quickly, and on the other hand, give a noticeable additional criteria for the control of the correctness of experimental or theoretical data.
The forth block of investigations that is supposed to carry out in the frame of the present Proposal is related with measurement of cumulative yields of fission fragments for minor actinides where the lack of experimental information is observed. In the Project #176, the data for the fission fragment yields were already obtained for 241Am as a by product at the study of (n, 2n) and (n, 3n) reactions. The results were presented at the International Conference on Nuclear Data for Science and Technology, which was held at Trieste, Italy, on May 19-24, 1997. The data-called an interest of specialists attended there. Since the Khlopin Radium Institute has necessary conditions for the investigations of such kind (qualified specialists, pure materials, special equipment) these could be carried out with a good quality here.
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