Nuclear Performance of Accelerator-Driven Systems with Infinite U - PowerPoint PPT Presentation

Nuclear Performance of Accelerator-Driven Systems with Infinite U ranium Material Sümer ŞAHİN 1 , Başar ŞARER 2 Yurdunaz ÇEL İ K 3 1 Atılım University, Faculty of Engineering, Ankara 2 Gazi University, Faculty of Science, Ankara 3 Gazi University, Institute of Science and Technology, Ankara

WORLD NUCLEAR POWER PLANTS CONCENTRATION

750 000 000 people have even not seen electrical light throughout their life !!!

Accelerator-driven systems (ADS)  Bombardment of heavy nuclei (A > 200) with high energetic protons (~400 MeV up to 1.5 GeV)  Spallation neutrons from thermal up to GeV range with maximum by 1-2 MeV

NUCLEAR MODELS Spallation reactions proceed through three successive stages: • pre-equilibrium stage • evaporation-fission stage • intranuclear cascade stage (INC) There are several criteria to discriminate the different intra-nuclear cascade models such as the medium, the collision, the stopping time, the nuclear surface and the Pauli blocking.

Options offered in the MCNPX code based on physics packages Bertini, ISABEL, INCL4: Intra-nuclear models Dresner, ABLA: Evaporation-fission models CEM2k: Cascade-exciton model

Bertini and ISABEL cascade- evaporation models use the “strict” application of the Pauli principle. Fast particles are tracked down to a cutoff energy, usually <10 MeV above the Fermi energy. INCL4 model uses the “statistical” application. Duration of the cascade stage is determined with calculation time.

Basic Assumption of Nucleus Models Bertini, ISABEL, CEM2k : Nucleus is a continuous medium. The nucleon densities are constant within the certain zones. Bertini: Nucleus is divided as 3 concentric spheres with different densities. Pauli principle “strict” . CEM2k: Nucleus is divided as 7 concentric spheres with different densities. ISABEL: Nucleus is divided as 16 concentric spheres with different densities. Pauli principle “strict” . INCL4: Nucleus is a bundle of individual nucleons moving in a given potential.

The spallation reaction is an interaction between a nucleon or a light nucleus of a few hundreds of MeV to a few GeV per nucleon and a target heavy nucleus. The INC model is generally considered to be valid when the incident particle has a sufficiently small de Broglie wavelength to interact with individual nucleons; this length should be smaller than the typical inter-nucleonic distances in the target nucleus.

In the INC stage the incident particle strikes a nucleon in the target nucleus and produces secondary particles. The primary and secondary particles can interact with other nucleons or be absorbed. These successive collisions lead to the excitation of residual nucleus. The cascade ends when all particles escape the nucleus. The second stage called pre-equilibrium is an intermediate stage between cascade and evaporation- fission stage. The kinetic energies of the particles emitted in this stage higher than those of the particles emitted in the evaporation stage. The third stage is the de-excitation of the excited residual nucleus remaining via a process of evaporation – fission after cascade stage.

Options offered in the MCNPX code based Investigated Combinations Bertini/ABLA Bertini/Dresner CEM2k INCL4/ABLA INCL4/Dresner ISABEL/ABLA ISABEL/Dresner Bertini/Dresner is default option recommended by MCNPX .

Scheme of the target-beam pipe system

Beam particle type: Protons Beam energy: 1 GeV Beam current: 1 mA Beam Power: 1 MW Target: Pb-Bi eutectic Number of source particle histories per MCNPX calculation: 2.5x10 5

Proton energy spectra in the beam window

Proton energy spectra in the target

Neutron energy spectra in the beam window

Neutron energy spectra in the target

Radial neutron flux in the target

Axial neutron flux in the target

Axial variation of the neutron flux on the target side face

Neutron leakage spectra from the target bottom face

Neutron leakage spectra from the target top face

Angular neutron leakage spectra from the target top face

Neutron leakage spectra from the target side face

Angular neutron leakage spectra from the target side face

Axial variation of the neutron flux in the beam window (n/(cm 2 .s.mA)

Neutron Energy deposition in the beam window

Proton energy deposition in the beam window

Energy dependent total heating in the beam window

Volume integrated neutron energy deposition in the target

Energy dependent total heating in the target window

Volume integrated proton energy deposition in the target

Axial variation of the proton heating in the target

Axial neutron energy deposition in the target

Radial neutron energy deposition in the target

Physics model Neutron Proton Pion Bertini/ABLA 2.95E+01 8.25E-02 2.00E-03 Bertini/Dresner 2.82E+01 8.19E-02 1.96E-03 CEM2k 2.93E+01 6.49E-02 1.95E-03 INCL4/ABLA 2.70E+01 9.41E-02 2.69E-03 INCL4/Dresner 2.58E+01 9.31E-02 2.70E-03 ISABEL/ABLA 2.87E+01 8.49E-02 2.06E-03 ISABEL/Dresner 2.75E+01 8.52E-02 2.00E-03 Neutron, proton and pion multiplicities per incident proton on target

Physics Model I Physics Model II Deviation (%) * Bertini/DRESNER INCL4/DRESNER 8.51 Bertini/DRESNER ISABEL/DRESNER 2.48 Bertini/DRESNER Bertini/ABLA - 4.6 Bertini/ABLA INCL4/ABLA 8.5 (4.26) Bertini/ABLA ISABEL/ABLA 2.7 (1.77) ISABEL/DRESNER ISABEL/ABLA -4.4 INCL4/DRESNER INCL4/ABLA -4.7 ISABEL/DRESNER INCL4/DRESNER 6.2 ISABEL/ABLA INCL4/ABLA 6.0 Differences in Neutron Multiplicity between Different Calculation Models

Physics model Bottom Top Side Total Bertini/ABLA 4.12E15 3.66E16 1.42E17 1.83E17 Bertini/Dresner 4.03E15 3.39E16 1.37E17 1.75E17 CEM2k 4.03E15 3.60E16 1.42E17 1.82E17 INCL4/ABLA 3.77E15 3.10E16 1.32E17 1.67E17 INCL4/Dresner 3.70E15 2.97E16 1.27E17 1.60E17 ISABEL/ABLA 4.16E15 3.55E16 1.39E17 1.79E17 ISABEL/Dresner 4.08E15 3.29E16 1.34E17 1.71E17 Differentiated Neutron Leakage out of Target for Selected Models [n/(s.mA)]

Neutron induced proton production in the beam window

Neutron induced deuterium production in the beam window

Neutron induced tritium production in the beam window

Neutron induced helium production in the beam window

Neutron induced proton production in the target

Neutron induced deuterium production in the target

Neutron induced tritium production in the target

Neutron induced helium production in the beam window

CONCLUSIONS A systematic comparison of seven different calculation models in MCNPX has lead to different results in neutron multiplicity, neutron leakage and neutron spectra . These will have also direct impact on neutron heating and material damage in the beam window, furthermore on technical data and performance of ADS as a whole power plant with respect to plant power, transmutation, material damage, etc.

The maximum value of the neutron flux in the target is observed on the axis ~ 10 cm below the beam window, where the maximum difference between 7 different models is ~ 15 %. The total neutron leakage out of the of the target calculated with the Bertini/ABLA is 1.83x10 17 n/s, and is about 14 % higher than the value calculated by the INCL4/Dresner (1.60x10 17 n/s).

Bertini/ABLA calculates top, bottom and side neutron leakage fractions as 20 %, 2.3 %, 77.6 % of the total leakage, respectively. They become 18.6 %, 2.3 %, 79.4 % with INCL4/Dresner combination.

MYRRHA: Major experimental Accelerator-Driven System (ADS) Reacto r core IVFS

Civilian nuclear power plants have produced nearly 1,700 tons of reactor-grade plutonium , of which about 274 tons have been separated and the rest is stored at reactor sites embedded in spent fuel Nuclear power plants in the European Union (~ 125 GW) produce yearly approximately 2500 tons of spent fuel , containing about 25 tons of plutonium and 3.5 tons of the “minor actinides (MA)” neptunium, americium, and curium and 3 tons of long-lived fission products Nuclear weapons nations have accumulated an estimated 250 tons of weapons-grade plutonium , most of it in the United States and Russia

The composition of the reactor grade plutonium ISOTOPES Reactor grade plutonium initial [%] 238 Pu 1.0 239 Pu 62.0 240 Pu 24.0 241 Pu 8.0 242 Pu 5.0 IAEA, Potential Of Thorium Based Fuel Cycles to Constrain Plutonium and Reduce Long Lived Waste Toxicity, IAEA-TECDOC- 1349, International Atomic Energy Agency, Vienna, Austria, p.55, Table 3.3.6 ( 2003) .

ISOTOPES Mass (kg/year) per unit PWR * 237 Np 15.1 238 Pu 16.1 239 Pu 205 240 Pu 120 241 Pu 72.7 242 Pu 41.6 241 Am 6 242m Am 0.00793 243 Am 21.8 244 Cm 15.6 245 Cm 1.74 Composition of MA in the spent fuel of a light water reactor Pressurised-water reactor, fuel with plutonium recycle, 1000-MW el reactor, 80% capacity factor, 33 MW.D/kg, 32.5 % thermal efficiency, 150 days after discharge (Nuclear Chemical Engineering, p. 370, Table 8.5)

Subcritical core configuration 86 cm