Neutronics Perturbation Calculation Method Study of Solid Breeder Tritium Breeding Blanket for TBR Enhancement

Tritium breeding blanket (TBB) is an essential component in a fusion reactor, which has functions of tritium breeding, energy generation, and neutron shielding. Tritium breeding ratio (TBR) is a key parameter to evaluate whether the TBB could produce enough tritium to achieve the tritium self-sufficiency (TBR >1) for fusion reactor. Current codes or software are hard to meet the requirements of high efficiency, high resolution, and high automation for neutronic optimization of TBB. In this article, the application of the density perturbation calculation on a solid breeder TBB was first performed. Then, the method of the geometry perturbation calculation based on the virtual density theory was studied. Results and comparison analysis indicate that the 1st + 2nd-order neutronic perturbation calculations (including the density perturbation and the geometry perturbation) results are consistent with the transport results under a perturbation of −15% to +15%. It is proven to be valid to use the perturbation calculation for rapid TBR enhancement study of the solid breeder TBB.

Statistical Analysis of Tritium Breeding Ratio Deviations in the DEMO Due to Nuclear Data Uncertainties

For the stable and self-sufficient functioning of the DEMO fusion reactor, one of the most important parameters that must be demonstrated is the Tritium Breeding Ratio (TBR). The reliable assessment of the TBR with safety margins is a matter of fusion reactor viability. The uncertainty of the TBR in the neutronic simulations includes many different aspects such as the uncertainty due to the simplification of the geometry models used, the uncertainty of the reactor layout and the uncertainty introduced due to neutronic calculations. The last one can be reduced by applying high fidelity Monte Carlo simulations for TBR estimations. Nevertheless, these calculations have inherent statistical errors controlled by the number of neutron histories, straightforward for a quantity such as that of TBR underlying errors due to nuclear data uncertainties. In fact, every evaluated nuclear data file involved in the MCNP calculations can be replaced with the set of the random data files representing the particular deviation of the nuclear model parameters, each of them being correct and valid for applications. To account for the uncertainty of the nuclear model parameters introduced in the evaluated data file, a total Monte Carlo (TMC) method can be used to analyze the uncertainty of TBR owing to the nuclear data used for calculations. To this end, two 3D fully heterogeneous geometry models of the helium cooled pebble bed (HCPB) and water cooled lithium lead (WCLL) European DEMOs were utilized for the calculations of the TBR. The TMC calculations were performed, making use of the TENDL-2017 nuclear data library random files with high enough statistics providing a well-resolved Gaussian distribution of the TBR value. The assessment was done for the estimation of the TBR uncertainty due to the nuclear data for entire material compositions and for separate materials: structural, breeder and neutron multipliers. The overall TBR uncertainty for the nuclear data was estimated to be 3~4% for the HCPB and WCLL DEMOs, respectively.

Analisis Konfigurasi Bahan Bakar Terhadap Produktivitas Fisil pada Fast Breeder Reactor (FBR)

Analisis konfigurasi bahan bakar terhadap produktivitas fisil pada Fast Breeder Reaktor (FBR) telah dilakukan. Konfigurasi bahan bakar dirancang dalam 5 variasi dengan 2 kategori yaitu konfigurasi homogen (inner dan outer) serta heterogen dengan fraksi bahan bakar yang sama yaitu 45 %. Perhitungan dilakukan dengan metode komputasi menggunakan kode FI-ITB.CHI yang dikembangkan dalam bahasa pemrograman Borland Delphi 7.0 Bahan bakar yang digunakan adalah campuran uranium-plutonium nitrida (Un-PuN) dan pendingin timbal bismuth (Pb-Bi) pada teras reaktor 2-D (dua dimensi) geometri r-z (silinder). Hasil perhitungan difusi neutronik menunjukkan bahwa pada semua konfigurasi bahan bakar yang diamati diperoleh nilai kritikalitas teras melalui pengaturan fraksi pengayaan (enrichment) pada setiap bagian teras. Fraksi pengayaan rata-rata yang terkecil untuk mencapai keadaan kritis ditunjukkan pada konfigurasi homogen-outer. Hasil analisis menunjukkan bahwa nilai distribusi fluks neutron yang paling tinggi diperoleh pada konfigurasi heterogen dan nilai distribusi daya dengan nilai power peaking factor (ppf) terendah diperoleh pada konfigurasi homogen. Nilai densitas atom bahan fisil yaitu 239Pu paling besar peningkatannya terjadi pada konfigurasi homogen-inner 2 sebagai hasil reaksi fisi bahan bakar setelah 1 siklus (4 tahun) operasi. Nilai BreedingRatio (BR) untuk seluruh konfigurasi bahan bakar masih dalam rentang nilai yang diharapkan (BR>1) namun nilai BR paling baik ditunjukkan pada konfigurasi homogen-inner 2 yaitu dengan nilai 1,17.Kata kunci: FBR, konfigurasi bahan bakar, fisil, breeding ratio.

Design and simulation of a blanket module for TOKAMAK reactors

In this paper, we simulated an appropriate model for an advanced breeding blanket of future TOKAMAK fusion reactors with solid breeder (Li4SiO4) building material in the form of pebble beds, ODS ferritic steel as structural material and Beryllium as neutron multiplier. With the MCNPX code, the efficiency of this proposed model for the production and self-sufficiency of tritium was investigated. Total tritium breeding ratio of 1.15 is achieved. The helium-cooled pebble bed system and parameters of temperature and pressure are investigated by COMSOL multiphysics simulating software. The temperature of helium as cooling gas never exceeded 530[Formula: see text]C and the tolerable temperature of beryllium was obtained at 650[Formula: see text]C. In the proposed design, it is adequate to enrich the 6Li to 40%.

Analisis Burn Up pada Reaktor Pembiak Cepat Berpendingin Pb-Bi dengan Variasi Fraksi Bahan Bakar dan Bahan Pendingin

Telah dilakukan simulasi pada desain Reaktor Pembiak Cepat Berpendingin Logam Cair (Pb-Bi), menggunakan kode simulasi berbasis bahasa pemograman Delphi 7.0 untuk menganalisis pembiakan bahan fisil 239Pu. Perhitungan diterapkan pada teras reaktor 2-D (dua dimensi) geometri r-z (silinder) dengan menempatkan bahan fertil (blanket) pada teras bagian luar. Teras reaktor dirancang beroperasi pada daya 150 MWt dengan bahan bakar campuran uranium dan plutonium nitrida dan pendingin logam cair Pb-Bi. Simulasi dilakukan terhadap beberapa variasi fraksi bahan bakar (35%, 40% dan 45%) dan bahan pendingin yang diawali dengan penyelesaian persamaan difusi untuk mendapatkan nilai faktor multiplikasi, fluks neutron dan distribusi daya. Nilai fluks yang diperoleh digunakan untuk menghitung perubahan densitas atom selama reaktor beroperasi yang diperlukan untuk menganalisis susutan bahan bakar. Hasil perhitungan menunjukkan bahwa nilai faktor multiplikasi neutron (keff) untuk semua fraksi berada dalam kondisi kritis. Untuk mencapai kondisi kritis diperlukan pengaturan enrichment, pada fraksi bahan bakar yang rendah diperlukan enrichment yang besar dan untuk fraksi bahan bakar yang tinggi diperlukan enrichment yang kecil. Pengaturan enrichment berpengaruh juga pada nilai distribusi fluks neutron, distribusi daya, densitas bahan bakar, breeding ratio dan burn up. Kinerja neutronik yang paling optimal diperoleh pada fraksi bahan bakar 45% dan pendingin 35%. Densitas plutonium tertinggi diperoleh pada fraksi bahan bakar 45% yang merupakan hasil reaksi fisi bahan bakar setelah 1 siklus (4 tahun) operasi. Nilai pertambahan densitas isotop diketahui dari nilai Breeding Ratio (BR) yang besar dari 1.Kata kunci: breeding ratio, bahan fisil, burn up, reaktor pembiak cepat

Fuel Cycle Performance of Fast Spectrum Molten Salt Reactor Designs

4 fast-spectrum molten salt conceptual designs have been selected for fuel cycle performance analysis. 3D full core and 2D unit cell models have been developed to justify the possibility to use a simplified model for computational-heavy depletion simulation with truly continuous online reprocessing. Finally, 60-years depletion simulation for Molten Salt Fast Reactor (MSFR) shown lifetime breeding ratio 1.0072 and doubling time 139 years in Th/U fuel cycle.