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Comparison of the neutronic properties of the (Th-233U)O2, (Th-233U)C, and (Th-233U)N fuels in small long-life PWR cores with 300, 400, and 500 MWth of power

Lapanporo Boni Pahlanop, Su’ud Zaki, Mustari Asril Pramutadi Andi

Nukleonika

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2024

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Vol. 69, No. 1

3--12

EN

The neutronic characteristics of (Th-233U)O2, (Th-233U)C, and (Th-233U)N have been compared in small long-life pressurized water reactors (PWRs). Neutronic calculations were carried out at 300 MWth, 400 MWth, and 500 MWth with two cladding types: zircaloy-4 and ZIRLO (Zr low oxygen). They were performed using the Standard Reactor Analysis Code (SRAC) and JENDL-4.0 nuclide data, dividing the reactor core into three fuel zones with varying 233U enrichment levels, ranging from 3% to 9% and fl uctuating by 1%, employing the PIJ module at the fuel cell level and the CITATION module at the reactor core level. In addition, 231Pa was added as burnable poison (BP). The (Th-233U)N fuel demonstrated superior criticality compared to the other fuel types, as it consistently achieves critical conditions throughout the reactor’s operating cycle with excess reactivity <1.00% dk/k for several fuel confi gurations at the 300 MWth and 400 MWth power levels. Moreover, the (Th-233U)N and (Th-233U)C fuels exhibited similar and fl atter power density distribution patterns compared to the (Th-233U)O2 fuel. The power peaking factor (PPF) value was relatively higher for (Th-233U)O2 fuel than the other two fuels. The (Th-233U)N fuel exhibited the most negative Doppler coefficient, followed by (Th- 233U)C and (Th-233U)O2 fuels. Analysis of burnup levels revealed that the (Th-233U)O2 fuel achieved significantly higher burnup than the other two fuels.

2

Neutronic analysis of nanofluids as a coolant in the Bushehr VVER - 1000 reactor

Zarifi E., Jahanfarnia G., Veisy F.

Nukleonika

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2012

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Vol. 57, No. 3

375-381

EN

The main goal of this study was to perform the neutronic analysis of nanofluids as a coolant in reactor simulation. The variation of multiplication factor and thermal power have been investigated in the Bushehr VVER-1000 reactor core with using different nanofluids as coolant. In the applied analysis, water-based nanofluids containing various volume fractions of Al2O3, TiO2, CuO and Cu nanoparticles were used. The addition of different types and volume fractions of nanoparticles were found to have various effects on reactor neutronic characteristics. By using WIMS-D5 and CITATION code, the appropriate nanofluid with optimum volume percentage of nanoparticles was achieved. The results show that at low concentration (0.1% volume fraction) alumina is the optimum nanoparticle for normal reactor operation.

3

Study of boron dilution phenomenon in the core and fuel assemblies of Bushehr VVER-1000 reactor in normal operating conditions

Rahmani Y., Zarifi E., Pazirandeh A.

Nukleonika

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2010

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Vol. 55, No. 3

323-330

EN

The spatial temperature distributions in fuel and coolant, results in appearing local changes in those elements densities in the reactor core, and also due to the complete solubility of boric acid in the coolant, there will be a direct correlation between the changes in the boron concentration and the coolant density. Because of the gradual reduction of boron concentration, first a local positive reactivity will be inserted into the core which will cause slight thermo-neutronic fluctuations in the reactor core. Of course, the trend of this process in the case of excessive reduction of the density of the coolant and evaporation of water (accident scenarios) will be reversed and subsequently the negative reactivity will be given to the system. With regard to the importance of this phenomenon, the spatial changes of boron concentration in the core and fuel assemblies of Bushehr VVER-1000 reactor have been examined. In line with this, by designing a complete thermo-neutronic cycle and by using CITATION, WIMS D-5 and COBRAN-EN codes, coolant temperature distribution and boron concentration will be calculated through this procedure, which first by using the output results of WIMS and CITATION codes, the thermal power of each fuel assembly will be calculated and finally, by linking these data to COBRA-EN code and using core and sub-channel analysis methods, the three-dimensional (3D) calculations of boron dilution will be obtained in the core as well as the fuel assemblies of the reactor.