Nuclear Data for ADS and Transmutation Joint TREND/SANDAT proposal for FP6 ADOPT- Meeting, Dec E. Gonzalez-Romero (CIEMAT) Introduction Sensitivity Analysis Integral Experiments Measurements

INTRODUCTION After the meeting on October 31st, the participants on the TREND and SANDAT Expressions of Interest decided to join for the preparation of the proposal for the FP6. The result will be organized in 6 workpackages (WP): 1Coordination 2Sensitivity Analysis 3Low and Intermediate differential cross section and nuclear data measurements 4(Low energy) integral measurements 5Low energy theory and evaluation (including dissemination) 6High Energy theory and Experiments Point 6 will be mainly based on the TREND proposal Point 3 and 5 were fundamental part of both TREND and SANDAT and will merge the proposals Point 2 and 4 will be mainly based on the SANDAT proposal

Nuclear Data Beyond the FP5- Sensitivity Analysis: Focusing the nuclear data on its final P&T application The FP5 guidelines for measurement priorities: direct contributions to the reaction rates, availability of the samples, and differences observed between different nuclear data bases. This simple sensitivity analysis has proven its merits within the nTOF-ADS program by indicating the isotope, reaction and required accuracy and served to reduce unnecessary efforts. However a full systematic sensitivity analysis is missing and has been requested both in the meetings of the BASTRA cluster and in the WPPT of the NEA/OCDE. Only this systematic sensitivity analysis can provide precise scientific arguments to properly define the impact of the data uncertainty and the priority of needs for new measurements. This sensitivity analysis have to evaluate the impact of the uncertainties of the nuclear data on: the performance (power and operativity), safety (dynamic parameters, shielding, radioprotection,...) and cost (power, shielding,...) of - the transmutation device (ADS and critical reactors) and - the final inventory of the repository depending on the nuclear cycle options.

Parameters for the sensitivity analysis Any detailed engineering design of a transmutation device or of fuel cycle will have to manage the consequences of the nuclear and other technical data uncertainties. However whereas some corrections (like the power level of an ADS) are easy to handle (beam intensity adjustment), others affect the viability or final result of the concept or may have large economical impact. The sensitivity analysis has to be concentrated on the effect of the nuclear data uncertainties on these second type of parameters. Some important parameters: Keff : a) At construction -> overdesign of fuel and control system (rather than n-multiplication) b) Evolution with burn-up must be predictable Dynamic parameters:  eff, neutron lifetime, Doppler effect, Reactivity coefficients,... Critical transmuters, ADS in abnormal conditions, Evolution with burn-up. Shielding requirements: Related with the small part of the very energetic spallation neutrons. Material damage: In particular in the window, gas releasing reactions. The fuel cycle: Equilibrium composition of multiply-recycled fuels in closed fuel cycles. The composition and amount of the different spent fuels and of the final disposal: Activation of the fuel, coolant, structures, accelerator,... + the fission & spallation products. The spallation source performance: Production and transport of high energy neutrons,  *.

Some of the New measurements needed Keff, reactivity coefficients and the power of the transmutation system: To extend the fission measurements of the new relevant isotopes of Pu, Np, Am and Cm, from the pure cross section to neutron multiplicity, delayed neutron fractions, neutron energy spectra and fission fragments production, all of them as far as possible as a function of neutron incident energy. Neutron spectrum, Keff, isotopic composition: Inelastic cross section and of the (n,xn) reaction and characteristics of secondary neutrons, both for the main fuel components and matrix and for the heavy components of the coolant and structural materials. Shielding related problems: Precise double differential cross section measurements of elastic scattering and total cross sections for the main isotopes of the fuel, coolant and structural and shielding materials in a wide energy range. Evolution of the fuel composition, equilibrium composition and isotopic content of the finally disposed wastes: Capture cross sections and other activation reactions. Particular cases: Actinides with short or intermediate half-live. What is needed 238 Pu (88 y) Capture + Fission + Total Pu (14 y) Capture + Fission + Total m Am (141 y) High SF > Small massMainly Fission 243 Cm (29 y)Mainly Fission? 244 Cm (18 y) High SF -> Small massCapture + Fission + Total Cm (4727 y) High SF -> Small massCapture + Fission + Total Cm ( y) Capture + Fission

Integral Measurements Complementary to differential measurements: 1) Able to work with very small samples 2) Able to handle difficult radioactive samples 3) For main isotopes may reach higher absolute precision 4) Sensitive to different systematic uncertainties than the differential measurement 5)Different energy regions 6)Provide benchmarks for the calculations with updated codes and data libraries Worse capacity to describe the energy dependence and to analyze some sources of systematic. Example of complementarity: The fission cross section of several of the short lived Actinides can be measured by transfer reactions but there suffer from Theoretical uncertainties and are difficult to apply to the low (resonance) energy region Or directly by integral experiments in fission chambers averaged on different energy spectra.

Facilities In this proposal such integral measurements will be performed, at least, (other reactors may be considered if available from new partners) in the MMF facility in INR at Troïtsk/RF 350 MeV/100 µA proton beam - upgradable to 600 MeV/0.5 mA, two irradiation in-beam facilities and Pb spallation target, a 6 MW Pb-Bi cooling system and a variety of fuel pins. BFS critical facility of SSC IPPE in Obninsk/RF (+BN350) SN-3 reactor of RIAR at Dimitrovgrad/RF (+BOR60) ILL (Mini-INCA) Note that the MMF irradiation environment will be very similar to the final ADS one, because the MMF will, in fact, be a lead-bismuth cooled subcritical core. Some of these facilities will also be able to irradiate the main components of the future fuel and by several radiochemical techniques and could allow to study the fission fragment distribution for different fissionable actinide isotopes. Methodologies Radiochemical and isotopic analysis Fission Chambers, Activation Foils Small sample worths by oscillation technologies For larger samples: Reactivity effects (Doppler, Void effects,...) Samples include: Np237, Pu(238,239,240,241,242), Am(241,243,242m?), Cm(243,244) + Pb and Bi

Summary A joint proposal of nuclear data for ADS and P&T is under preparation combining the TREND and SANDAT EOI and including: Sensitivity analysis, differential and integral measurements at low and high energy, and the theory required to evaluate and extrapolate the experimental data. The sensitivity analysis will allow to identify and quantify the practical consequences of the nuclear data uncertainties, a basic element for any transmutation and fuel cycle design. In addition, it should allow to identify the most relevant uncertainty sources. The differential and integral measurements will improve our knowledge on the nuclear data: initially the a-priori more sensible and with worse experimental information isotopes and reactions will be addressed, in a second phase the reactions pinpointed by the sensitivity analysis will be measured. Several of these measurements will only be possible by combination of differential and integral measurements (short lived actinides). The theory will allow to use (in the form of codes or libraries) the experimental data within the standard simulation tools used for transmutation devices and fuel cycle design and assessment.