SPES cyclotron-driven fast neutron irradiation facility aimed at nuclear data needs for next generation nuclear reactors: the FARETRA project at LNL

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1 INFN-LNL Istituto Nazionale di Fisica Nucleare Laboratori Nazionali di Legnaro SPES cyclotron-driven fast neutron irradiation facility aimed at nuclear data needs for next generation nuclear reactors: the FARETRA project at LNL Juan Esposito INFN-ANSALDO meeting Auditorium di Ansaldo Energia Feb 07, 2011 Meeting INFN-NSALDO, Genova, Feb. 07, 2011

2 The energy problem: a new approach Recently, renewed interest in nuclear energy due to: continously increasing energy demand; growing concern over production of greenhouse gases and related climate changes To satisfy the world energy demand (in particular from developing countries), minimizing the impact on the climate, it is necessary a mix of energy sources which includes nuclear energy (Intergov. Panel on Climatic Change, IPCC-ONU, Valencia, 17 Nov. 2007). However, currently operating nuclear reactors are affected by two limitations: inefficient use of uranium resources (may become a problem in the medium term) the production of nuclear waste Rivolutionary Generation IV reactors would overcome major problems of current reactors, thanks to the implementation of a closed fuel cycle (recycling of nuclear waste). Other options now being considered are: Accelerator Driven Systems (nuclear waste incineration) Use of the Th/U fuel cycle (currently being devoloped in India) 2 Meeting INFN-NSALDO, Genova, Feb. 07, 2011

3 The nuclear waste problem due to current (Gen-II) reactors Activation materials Recovered uranium TRU Actinides: Np, Pu,, Am, Cm Fission fragments Uranium ores Uranium ores The radiotoxicity of fission fragments decays in a few hundred years. It is sufficient to store them in man-made deposits. The radiotoxicity of actinides remains high for millions of years, so that they have to be disposed in geological sites. The main problem in the nuclear waste is due to plutonium and minor actinides. 3 Meeting INFN-NSALDO, Genova, Feb. 07, 2011

4 Nuclear physics of next Gen IV/ADS reactor systems Significant combustion cycle improvement would result by burning not only U and Pu but even most of waste material (including long-lifetime actinides) produced by current thermal (Gen II-III) reactors: Np, Am, Cm series. Most minor actinides have a fission threshold (~ 1 MeV) To burn nuclear waste fast reactors (or ADS systems) are needed Gen IV fast breeder reactors fulfill a fuel closed cycle (better use of U fuel minimizing waste production) About 2 orders of magnitude increase in output power per unit mass of U Differential neutron flux dn/dlog(e) x n/cm 2 /s (without 1 threshold) Typical neutron spectrum in fast Neutron (Gen IV/ADS) Spectrum like reactors Fissile isotopes Am Pu Pu Neutron cross sections (with threshold) Cm Np 243 Am 1 MeV 1x10 4 1x10 5 1x10 6 1x10 7 Neutron energy, ev Fission Cross section, barn The development of Gen IV fast reactors requires cross section data for several actinides in a wide energy range, mainly in the fast region (E n >100 kev). 4

5 New ADS /Gen IV reactors design requirement Design of innovative new reactor types is basically done by using: - performant, state of the art codes for Monte Carlo simulation - reliable cross section libraries with known data precision - benchmarking The European project ELSY 5 Meeting INFN-NSALDO, Genova, Feb. 07, 2011

6 Database problems: imprecise data extrapolation (example) Cross section (mb) Fe(n,np) 56 Mn EXFOR Ikeda et al. ENDF/B-VI JENDL-3.2 JEF-2.2 this work Neutron energy (MeV) Meeting INFN-NSALDO, Genova, Feb. 07, 2011

7 Database problems: inaccuracy in data files (example) cross section (mb) Paul (1953) Cross (1963) Preiss (1960) Qaim (1977) Bahal (1984) Qaim (1984) Viennot Ribansky (1985) Viennot (1991) Molla (1991) Osman (1996) Val'ter (1962) Levkovskiy (1969) IRMM 61 Ni(n,p) 61 Co Model prediction 0 61 Co: N=24/2.499 MeV; 6.48/-.89: D N=11/1.682 MeV; 6.85/-.87: 0.95 N=24/2.499 MeV ; 6.85/-.75: 1.04 TALYS_0.49 0=1.50 kev neutron energy (MeV) Meeting INFN-NSALDO, Genova, Feb. 07, 2011

8 New nuclear data needs: cross section measurements Data on a large number of isotopes are needed for design of advanced systems and for improving safety of current reactors. Nuclear fuel (U/Pu and Th/U cycles) Th, U, Pu, Np, Am, Cm Long-lived Fission Products 99 Tc, 103 Rh, 135 Xe, 135 Cs, 149 Sm (n,γ) Structural and cooling material Fe, Cr, Ni, Zr, Pb, Na,... (n,f), (n,γ) all NEA/WPEC-26 (ISBN ) The overall list of requirements is rather long: capture cross sections of 235,238 U, 237 Np, Pu, 241,242m,243 Am, 244 Cm fission cross sections of 234 U, 237 Np, 238, Pu, 241,242m,243 Am, Cm FP VII EURATOM requests Topic: Fission : Improved nuclear data for advanced reactor systems. The combination of advanced simulation systems and more precise nuclear data will allow optimising the use of and need for experimental and demonstration facilities in the design and deployment of new reactors. A concerted effort including new nuclear data measurements, dedicated benchmarks (i.e. integral experiments) and improved evaluation and modelling is needed in order to achieve the required accuracies. The project shall aim to obtain high precision nuclear data for the major actinides present in advanced reactor fuels, to reduce uncertainties in new isotopes in closed cycles with waste minimization and to better assess the uncertainties and correlations in their evaluation. 8

9 New nuclear data needs: cross section measurements Necessary to measure cross sections in a wide energy range, high accuracy and high resolution (resonances are important for selfabsorption in fuel elements) Unresolved resonance region Cross section measurements with Time of flight techniques are under way worldwide at TOF facilities, (GELINA, n_tof, in Europe, LANSCE, Los Alamos, etc ) in order to reduce uncertainties for reactor applications. Thermal region Resolved resonance region High energy For shorter lived isotopes like e.g. 238 Pu, 241 Pu, 242m Am, 243,244 Cm, etc existing facilities however cannot provide sufficiently intense neutron beams. In such cases, a valuable alternative experimental technique is represented by integral measurements, which exploit relatively intense neutron fluxes with suitable energy distributions (e.g. the European Project Myrrha). 9

10 The SPES LNL: a multi-user project High intensity proton linac: TRIPS source TRASCO RFQ 30 ma, 5MeV Neutron facility for Medical, Astrophysics and Material science. Neutron source up to n s 1 Thermal neutrons: 10 9 n s 1 cm 2 Applied Physics with proton beam 70 MeV 450 μa Primary Beam: 300 μa, 70 MeV protons from a 2 exit ports Cyclotron Production Target: UCx fission s 1 Re accelerator: ALPI Superconductive Linac up to 11 AMeV for A=130 Approved for construction

11 The SPES Cyclotron: main data Accelerated particles: H - Variable Energy: 35 MeV - 70 MeV Starting beam current available 700 µa maximum beam current per port 500 µa Extraction system: Stripper H - Beam shared on two exit ports Performances: exit1: 300µA H - 40MeV exit2: 400µA H - 70MeV Dual beam operation (beam current upgrade program to 700 µa) Running time > 5000 h/year Minimum Beam Loss to avoid activation (< 5%)

12 SPES ISOL facility layout: Level -1 Application bunker2 Cyclotron RIB selection and transport ISOL bunker2 Application bunker1 ISOL bunker1 Low energy experimental area

13 FARETRA FAst REactor simulator for TRAnsmutation studies Proponenti: J. Esposito, N. Colonna, P. Boccaccio Purpose: an accelerator-based neutron facility able to provide, in a proper irradiation chamber, a GenIV-like fast neutron spectrum to start cross sections integral measurements on actinides fission fragments and structural materials, which main nuclear information are still lacking for Proposal: Using the SPES cyclotron proton beam (40-50 MeV) on a (Be,W o Pb) neutron converter and a proper neutron spectrum shifter system SPES Cyclotron driver Project goal: Neutron source level: Sn ~ s 1 moderation efficiency: cm 2 Total neutron flux expected: Φ n = ~ cm 2 s 1 1 μgr 238 Pu (87 y, 0.6 MBq) σ(n,f) ~ 1 b Expected Transmutation Rate = 20 c/s

14 Preliminary modeling of FARETRA facility Al outer spectrum shifter Fe inner spectrum shifter Proton beam pipe Pb gamma shield (inner) Poly-B neutron shield W conical target Proton beam pipe H 2 O target cooling feed through system Conical W target 70 cm H 2 O moderator volume CF2+Pobyboron shielded Irradiation chamber 75 cm 70 cm Insertion / extraction rods Fe inner spectrum shifter

15 The experimental neutron spectra W(p,xn) Ep=50 MeV T. Aoki, M. Baba, S. Yonai, N. kawata, M. Hagiwara, T. Miura, T. Nakamura, Measurement of Differential Thick Target Neutron Yields of C, Al, Ta, W(p,xn) for 50 MeV Protons; Nuclear Science and Engineering, 146, (2004) ; The present evaporation nuclear models implemented inside the most used transport codes (MCNPX, FLUKA, GEANT) are known to underestimate the neutron yielding by a factor 2-4 in the MeV region. In such a preliminary study the (p,xn) stage has been skipped, by directly using the experimental double differential data at 50 MeV for the neutron source production by tungsten target in the facility modeling.

16 Neutron spectrum inside irradiation chamber MCNPX calculation results (Preliminary) Accelerator-driven Systems (ADS) and Fast Reactors (FR) in Advanced Nuclear Fuel Cycles: A comparative study NEA-OEDC, 2002 FARETRA facility Moderation Efficiency (10 ev 10 MeV) : ~ Integral neutron flux: Φ n = ~ cm 2 s 1