Zaki Su'ud

Comparative study on safety performance of nitride fueled lead-bismuth cooled fast reactor with various power levels

Abstract In the present study safety performance of nitride fueled lead-bismuth cooled fast reactors of several sizes (150 MWt ∼ 2500 MWt) but all having maximum burn-up of about 9∼11 % HM are evaluated and compared. Small reactors can be operated up to 12 years, and large reactors(2500MWt) can be operated up to about 4 years without refueling or fuel shuffling. In each reactor excess reactivity is minimized up to below β eff in order to eliminate super-prompt critical accident. The ULOF and UTOP accident simulation was performed for each design and the results showed that all reactors could survive both accidents passively/inherently. However the temperature margin, especially for cladding, is larger for smaller reactor.

Preliminary design study of the ultra long life fast reactor

Abstract A preliminary design study of the ultra long life fast reactor has been performed. In the present study, a parametric survey was carried out for three regioned spherical reactors with metallic fuels. Changes of multiplication factor, conversion ratio, and peak power density during burnup were analyzed. The calculation results showed that 40 years reactor life time without refueling can be achieved by choosing appropriate values for the initial plutonium enrichment, fuel volume fraction, and size of each corresponding region. For this design the maximum excess reactivity can be reduced to a few percent by shifting the position of the power peak from the outer to the inner region of the core along burnup. Especially, dividing core and blanket into two regions, respectively, and adjusting parameters of each region reduced the excess reactivity during burnup to below 0.2%Δk .

Design study of long-life Pb-Bi cooled fast reactor with natural uranium as fuel cycle input using modified CANDLE burn-up scheme

This paper reports a conceptual design study of Pb-Bi cooled fast reactors with a fuel cycle that needs only natural uranium input. In this design, the CANDLE burn-up strategy is slightly modified by introducing discrete regions. The reactor cores are subdivided into several parts with the same volume in the axial directions. The natural uranium is initially put in region 1, after one cycle of ten years of burn-up it is shifted to region 2 and region 1 is filled with fresh natural uranium fuel. This concept is applied to all regions. From the parametric survey results, the region shuffling scheme and fuel volume fraction have large effect on the criticality of the core. Also, by putting regions 1 and 2 near region 10, we get some significant gain in effective multiplication factors. Core radius, core axial width, radial reflector width and axial reflector width have some impact on the initial effective multiplication factor value, but not as great.

Conceptual design study on very small long-life gas cooled fast reactor using metallic natural Uranium-Zr as fuel cycle input

A conceptual design study of very small 350 MWth Gas-cooled Fast Reactors with Helium coolant has been performed. In this study Modified CANDLE burn-up scheme was implemented to create small and long life fast reactors with natural Uranium as fuel cycle input. Such system can utilize natural Uranium resources efficiently without the necessity of enrichment plant or reprocessing plant. The core with metallic fuel based was subdivided into 10 regions with the same volume. The fresh Natural Uranium is initially put in region-1, after one cycle of 10 years of burn-up it is shifted to region-2 and the each region-1 is filled by fresh Natural Uranium fuel. This concept is basically applied to all axial regions. The reactor discharge burn-up is 31.8% HM. From the neutronic point of view, this design is in compliance with good performance.

Power flattening on modified CANDLE small long life gas-cooled fast reactor

Gas-cooled Fast Reactor (GFR) is one of the candidates of next generation Nuclear Power Plants (NPPs) that expected to be operated commercially after 2030. In this research conceptual design study of long life 350 MWt GFR with natural uranium metallic fuel as fuel cycle input has been performed. Modified CANDLE burn-up strategy with first and second regions located near the last region (type B) has been applied. This reactor can be operated for 10 years without refuelling and fuel shuffling. Power peaking reduction is conducted by arranging the core radial direction into three regions with respectively uses fuel volume fraction 62.5%, 64% and 67.5%. The average power density in the modified core is about 82 Watt/cc and the power peaking factor decreased from 4.03 to 3.43.

Corrosion Study of Fe in a Stagnant Liquid Pb by Molecular Dynamics Methods

It has been investigated theoretically the corrosion phenomena of iron (Fe) in liquid lead (Pb) by molecular dynamics methods. The corrosion phenomena was regarded as a diffusion process in which the Fe atoms of bulk material spreading into a liquid Pb. The D diffusion coefficient of the corrosion was calculated. We reported the self‐diffusion coefficient of Fe in liquid Pb is DMD(750°) = 2.59×10−9m2/s. This is in the range of (1.31–5.75)×10−9 m2/s from literature and also closed to DRobertson(750° C) = 2.74×10−9 m2/s based on the Robertson curve.

Netronic Design of Small Long-Life PWR Using Thorium Cycle

A small long-life core loaded with thorium fuel and 231Pa as burnable poison material has been performed in Pressurized Water Reactor (PWR). Thorium cycle fuel has higher conversion ratio in the thermal spectrum domain and lower reactivity swing than the Uranium-Plutonium cycle fuel. 231Pa have very large capture cross section that can pressed reactivity in the beginning of life. The neutronic analysis result of infinite cell calculation shows that mixed nitride is better than oxide and carbide in thorium fuel system. In the present study we consider thorium nitride system with 3 ~ 8 % 233U percentage and 0.2~ 7% 231Pa as fuel for small PWR and can be burn up for the long time. The purpose of the study is to optimize the design of 350MWt PWR which can be operated without refueling in 10 years The core was designed by cylindrical two-dimension R-Z (radial and axial). The multigroup diffusion and Burn-up analysis was performed by SRAC-CITATION code using libraries based on JENDL 3.2. By using this concept, small PWR can be designed for long time operation with reduced excess reactivity until under 1 % and flatted power distribution during its operation.

The prospect of uranium nitride (UN) and mixed nitride fuel (UN-PuN) for pressurized water reactor

Design study of small Pressurized Water Reactors (PWRs) core loaded with uranium nitride fuel (UN) and mixed nitride fuel (UN-PuN), Pa-231 as burnable poison, and Americium has been performed. Pa-231 known as actinide material, have large capture cross section and can be converted into fissile material that can be utilized to reduce excess reactivity. Americium is one of minor actinides with long half life. The objective of adding americium is to decrease nuclear spent fuel in the world. The neutronic analysis results show that mixed nitride fuel have k-inf greater than uranium nitride fuel. It is caused by the addition of Pu-239 in mixed nitride fuel. In fuel fraction analysis, for uranium nitride fuel, the optimum volume fractions are 45% fuel fraction, 10% cladding and 45% moderator. In case of UN-PuN fuel, the optimum volume fractions are 30% fuel fraction, 10% cladding and 60% coolant/ moderator. The addition of Pa-231 as burnable poison for UN fuel, enrichment U-235 5%, with Pa-231 1.6% has k-inf mo...

Molecular dynamics simulation of corrosion mitigation of iron in lead-bismuth eutectic using nitrogen as corrosion inhibitor

The corrosion of structural materials used in fast nuclear reactor design is a current major problem. It is due to the use of liquid metal as a coolant candidate in the heat transfer system. The liquid metal as lead-bismuth eutectic was found to make high corrosion to structural material as steel. One of the solutions of this problem is to inject some inhibitor into liquid metal. In this current work we simulate the effect of nitrogen injection as inhibitor candidate. The simulation will predict the proper concentration of injected nitrogen and also observe the microscopic structure of the material before and after injection to know the ability of nitrogen as an inhibitor. The simulation follows the molecular dynamics method and for preliminary study we use iron material rather than steel. We also use lennard-jones potential for simplification of the study. It is from our simulation we see nitrogen shows better corrosion mitigation compare with oxygen as in our previous study. The effective inhibition can be achieved by injecting at least 0.056wt.% nitrogen. This amount seems to be able to reduce the corrosion level of iron till about 99.5% for high corrosion at temperature 750 °C.

Conceptual design study of small long-life PWR based on thorium cycle fuel

A neutronic performance of small long-life Pressurized Water Reactor (PWR) using thorium cycle based fuel has been investigated. Thorium cycle which has higer conversion ratio in thermal region compared to uranium cycle produce some significant of 233U during burn up time. The cell-burn up calculations were performed by PIJ SRAC code using nuclear data library based on JENDL 3.3, while the multi-energy-group diffusion calculations were optimized in whole core cylindrical two-dimension R-Z geometry by SRAC-CITATION. this study would be introduced thorium nitride fuel system which ZIRLO is the cladding material. The optimization of 350 MWt small long life PWR result small excess reactivity and reduced power peaking during its operation.