Obiettivo
Specific Objectives
-To study in a systematic manner the interaction of neutrons with matter and thereby provide the basic knowledge needed towards the establishment of a complete neutron data base;
-To provide experimental data for the improved neutron database according to the demands specified in the OECD high priority request list;
-To perform measurements of neutron cross sections and related phenomena, e.g. the Doppler Broadening of neutron resonances;
-To perform measurements of hitherto unknown neutron induced reactions and for cases where large discrepancies exist in present neutron data libraries;
-To perform measurements that provide the basic input data for theoretical model calculations used in neutron data evaluation.
Planned Deliverables
Doppler Broadening at low temperatures OECD & Nuclear Industry
This research provides important data for the temperature dependence of reactivity in nuclear reactors.
-240PuO2, 242PuO2: Now that the Pu samples have been prepared and tested as well as the Au samples (calibration purposes) the experiments will begin at the end of October 2001 and continue into 2002;
-Hf (metal): Analysis of the transmission cross-sections recently measured at different temperatures and different sample thickness and submission of the experimental data to the NEA databank;
Charged-particle emission cross sections OECD & Nuclear Industry
These experiments provide important data for radiation damage calculations where the objective is to remove discrepancies at 14MeV and fill the energy gap at 5-20MeV.
-(n,Ñ), (n,p) measurements at the Van de Graaff: A newly developed Time Projection Chamber (TPC) will be used to measure the 10B (n,Ñ) 7Li reaction in the 0.5-20MeV energy range. Further measurements are foreseen for structural materials;
-(n,Ñ), (n,p) measurements at the 150MeV linear accelerator: Experiments on
26Al (n,Ñ) 23Na and 36Cl (n,p) 36S cross sections in the resonance region;
-Measurements on the Ñ¡}Ñ~ branching ratio of the 10B (n,Ñ) 7Li reaction up to 1MeV (joint measurements with JRC project 61);
-Activation cross-sections for short-lived products: Finalisation, evaluation and publication of isomer and total cross-section measurements on isotopes of Mo and Pb, on 58Ni, 59Co and 129I, and on inelastic scattering to isomers of Au, Ag and Y. Determination of the 129I amount and the 127I/129I isotope ratio using different techniques (e.g. the k0 method and isotopic mass separation) with an uncertainty better than 5%. Measurement results will be compiled in EXFOR format and sent to the NEA databank with subsequent spreading to the USA, Japan and IAEA databases. Partial evaluations performed in the context of the Candidate Countries (CCs) collaboration and the WPEC subgroup will be compiled in ENDF format and submitted to the ENDF/A database in Brookhaven and the JEFF project of the OECD.
Reference Measurements on Actinides OECD & Nuclear Industry
This research is required for feasibility studies of the Th fuel cycle
-232Th(n,×): Complete the measurements in the 5-100keV energy range at the new experimental set-up on flight path 5 at 14 m.
-233Pa(n,f): Continuation of the measurements started in 2001. Improvement of the shielding configuration on the basis of MCNP calculations. Perform feasibility studies for capture measurements.
-234,236U(n,f): Complete measurements on 234U at a longer flight-path in order to improve the energy resolution in the resonance region and finalise fission yields measurements. Start measurements on 236U.
Cross sections for neutron absorbing materials OECD & Nuclear Industry
The basic data generated from this work is used for fission products and astrophysics.
82,84,86Kr(n,×) and ãtot: Prepare new gas targets for 82Kr and 84Kr (FZK).
Perform transmission measurements for 82Kr and analyse together with the previously measured capture data. For 84Kr, perform capture experiments and analyse together with the previously measured transmission data.
Summary of deliverables made by: 31/12/2001
Doppler Broadening at low temperatures OECD & Nuclear Industry
This research provides important data for the temperature dependence of reactivity in nuclear reactors.
-240PuO2, 242PuO2: The Pu samples were prepared and tested for homogeneity and isotopic content. Test experiments with Au samples for calibration purposes were also completed and the experiments are scheduled to begin in October 2001;
-Hf (metal): Hf measurements were completed at 20 K. Samples of 0.25 and 10 mm thickness were also measured at temperatures between 15K and 300K. All experimental measurements were completed. The data were analysed and average transmissions were calculated using a 33-group representation commonly used in reactor calculations. Comparison of the experimental results with three data libraries reveals the deficiencies in all present libraries. There, the treatment of self-shielding above 1keV needs to be re-considered.
Charged particle emission cross sections OECD & Nuclear Industry
These experiments provide important data for radiation damage calculations where the objective is to remove discrepancies at 14MeV and fill the energy gap at 5-20MeV.
-(n,Ñ), (n,p) measurements at the Van de Graaff: Measurements were performed with a polished Ta blank substrate in order to uniquely identify interferences produced by the 10B(n,Ñ)7Li reaction. The data acquisition system based on the 12 bit PCI wave-form digitiser was also successfully used for the measurement of (n,×) reactions at the 150MeV linear accelerator for ADS applications (n_TOF collaboration). Using the newly developed Time Projection Chamber (TPC) and the T(p,n)3He reaction as neutron source, high quality data have been measured for the 10B(n,Ñ)7Li and 58Ni(n,Ñ)55Fe reactions. The first reaction has been used to test the performance of the TPC for the study of (n,Ñ) reactions on light elements. For the 58Ni(n,Ñ)55Fe reaction the particle groups Ñ0, Ñ1, Ñ2, and Ñ3-Ñ4 have been clearly resolved and identified. The angular distribution has also been determined. The TPC was moved from the R3 beam line to the zero-degree beam line in order to avoid interference with the fission experiments at R3.
-(n,Ñ), (n,p) measurements at the 150MeV linear accelerator: Experiments on 26Al(n,Ñ)23Na and 36Cl(n,p)36S cross sections in the resonance region were performed on schedule and the report on the 17O(n,Ñ)14C in the resonance region was finalised.
Activation cross sections for short-lived products OECD & Nuclear Industry
These experiments provide important data for radiation safety evaluation.
-Short-lived products: A new spectrum correction method was developed and irradiations for missing energy points were completed. 6 data points were obtained for the 59Co(n,2n)m+g58Co isomeric ratio and 3 points for the isomeric ratio of the 58Ni(n,p)m+g58Co reaction. The new sample changer system was debugged and the feasibility of activity measurements for half-lives below 3 seconds was demonstrated. The work on vanadium has been completed and submitted for publication. This is the first completed project task within the ENLARGEMENT activities. Isomer and total cross section measurements on 59Co were completed and work started on 129I, 58Ni(n,2n), Pb, Ag, Au and Y inelastic scattering to isomers, and Pb(n,2n) to a 6 s half life. Four reaction cross-sections on 204Pb and 206Pb were completed. A large number of reactions cross-sections measurements (including isomer production cross sections) were completed for Mo isotopes. The analysis of the reactions on lead isotopes was completed as well as the study of the 129I(n,2n) and 127I(n,2n) reactions. Two routes to the analysis of the 129I samples are proposed to be carried out by IRMM (a third one is already going on) where we will attempt to determine the 127I/129I isotope ratio and quantify the 127I amount (and possibly the 129I amount) by the k0 method. The overall target uncertainty is better than 5%.
Reference Measurements on Actinides OECD & Nuclear Industry
This research is required for feasibility studies of the Th fuel cycle.
-232Th(n,×): The experimental set-up for the transmission experiment on 232Th on flight path 5 at 14 m was tested and approved. Two runs were carried out with a 0.5 mm thick sample using different sets of black filters. A 0.5 mm thick 208Pb sample was also used for background determination. The data confirm the possibility of reducing the × energy threshold to 150keV and improving the signal-to-background ratio to values between 1.5 and 3.5. The full energy region of 5-100keV-neutron energy can be measured. The first two runs at the 14.37 m flight-path were analysed and normalised. Both data sets are consistent and within a systematic uncertainty of about 7%, the data agree with the literature. A third measurement campaign was completed, for which the data analysis is in progress and a fourth capture measurement experiment is planned.
-233Pa(n,f) (collab. with Studsvik): The 233Pa sample arrived from Studsvik, Sweden. Measurements were carried out and the data analysis is in progress. Preliminary results show that the 233Pa(n,f) fission cross section is lower than both evaluations (ENDFB-VI, JENDL3). Additional measurements were conducted for 233U(n,f) at the same incident neutron energies, needed for the correction of the in-growth and the influence of the shielding. The mass determination of Pa (very high electron background) was verified by alpha counting of the 233U daughter. The new value obtained was 10% smaller than the original and more consistent with our different measurements at different time periods. A new experimental campaign is foreseen for Feb-March 2002 and the sample has been ordered. MCNP calculations are presently continued in order to optimise the necessary shielding.
-234U(n,f): Analysis of the 234U(n,f) fission yield restarted taking into account the pulse-height defect for CF4. Serious analysis of the angular correlation showed that the full angular range could not be considered due to a too low gas pressure. The previously performed 234U(n,f) cross section measurements at GELINA and ILL were re-analysed because after control measurements it was found that the number of 234U atoms in the sample was 40% higher than originally quoted. In order to improve the energy resolution in the resonance region, new measurements are now under preparation at a longer flight-path. A suitable sample has been ordered.
Cross sections for neutron absorbing materials OECD & Nuclear Industry
The basic data generated from this work is used for fission products and astrophysics.
-82,84,86Kr(n,×) and ãtot: The REFIT code was upgraded and the 84Kr data were re-analysed using this upgraded version. The new analysis of the Xe data (for normalisation) was completed. For 82Kr, the capture data were completed. For 84Kr, transmission and capture data were completed and finalised and for 86Kr, capture data were completed and transmission data is pending. FZK, Germany will re-fill the two gas targets for the remaining measurements.
Output Indicators and Impact
Output indicators:
-Experimental (point-wise) data delivered in EXFOR format to the OECD-NEA databank;
-Resonance parameters (obtained by R-matrix fits to the experimental data) delivered to the OECD-NEA databank;
-Evaluated data submitted to JEFF and NNDC;
-Publications in refereed journals;
-Internal reports, JEFF reports, contributions to WPEC
-PhD theses.
Impact:
-Use of IRMM data in evaluation projects;
-Citation of IRMM experimental work in publications;
-Requests for measurement campaigns at GELINA and the Van de Graaff accelerator;
-Collaborations with external research groups.
Summary of the project
This project is part of the general IRMM programme on reference measurements in chemistry and physics related to fundamental material properties. A thorough knowledge of the interaction of neutrons with matter is of fundamental importance to assess the safe operation of nuclear reactors, model the ageing of presently operating power plants, develop new and advanced reactor concepts (e.g. the high-temperature reactor (HTR), the Th fuel cycle), and for various technological applications in energy production, mining, non-destructive testing. For these applications a complete and accurate neutronic database is required which is freely accessible to scientists and engineers working in various disciplines.
See also the related EU enlargement process pre-accession (pa) project.
Rationale
For the aforementioned applications a complete and accurate neutronic database is required which is freely accessible to scientists and engineers working in various disciplines. Databases of experimental as well as evaluated neutron data are maintained by the OECD-NEA, in particular the JEFF (Joint European Fusion and Fission File) library of evaluated neutron data. For many isotopes or neutron energy regions experimental data are lacking or are inconsistent, and then evaluations rely on model codes. Especially in these cases there is the necessity to improve the database by new and accurate measurements. The detailed requirements for neutron data measurements are collected in a high priority request list that is edited by the Working Party on International Evaluation Co-operation (WPEC) of the OECD-NEA.
The IRMM's Neutron Physics unit has a unique obligation under the Treaty of Rome for the measurement of neutron data. This requires highly specialised equipment. IRMM hosts a 150MeV electron linear accelerator (GELINA) and a 7MV Van de Graaff accelerator as well as specifically dedicated laboratories. The GELINA time-of-flight facility has the best energy resolution worldwide. This makes the IRMM the only European laboratory (and one out of 2 or 3 in the world) that is capable of producing these data over an energy range of a few meV to about 20MeV. IRMM has a long-standing expertise in this field and has attained worldwide recognition for producing top-level neutron data measurements.
Campo scientifico (EuroSciVoc)
CORDIS classifica i progetti con EuroSciVoc, una tassonomia multilingue dei campi scientifici, attraverso un processo semi-automatico basato su tecniche NLP. Cfr.: Il Vocabolario Scientifico Europeo.
CORDIS classifica i progetti con EuroSciVoc, una tassonomia multilingue dei campi scientifici, attraverso un processo semi-automatico basato su tecniche NLP. Cfr.: Il Vocabolario Scientifico Europeo.
- scienze naturali informatica e scienze dell'informazione scienza dei dati
- scienze naturali scienze fisiche fisica nucleare fissione nucleare
- scienze naturali scienze fisiche fisica teoretica fisica delle particelle acceleratore di particelle
- scienze naturali informatica e scienze dell'informazione basi di dati
- scienze naturali scienze fisiche astronomia astrofisica
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Coordinatore
B-2440 Geel
Belgio
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