Numerical and experimental analysis of a rectangular single-phase natural circulation loop with asymmetric heater position

Numerical approach for estimating the conditions for natural circulation in a simple nuclear passive system

Strand Test Facility has been constructed and will be used for passive reactor core cooling simulation research without using a pump or outside force, so that the movement of water flow occurs naturally. One important component of the FASSIP-02 is the water cooling tank (WCT), in addition to piping, expansion tanks (ET) and water heating tanks (WHT). WCT containing water such as a pond that functions to take heat in the water from the FASSIP-02 piping system with a position at an altitude of 11 meters. The total load of water and tank is 10 tons and for safety and security factors during operation it is necessary to analyze the mechanical strength of the WCT. Analysis is done by simulating mechanical stress conditions and translational displacement to determine the safety of WCT when operating. The stages of analysis include making a 3-dimensional model equipped with the mechanical properties of the material used, giving a load on the 3-dimensional WCT model, giving restrain to simulate the stable condition of the 3-dimensional model and testing it in simulation. The results of the analysis show that the mechanical stress on the WCT is still in the elastic area of the Carbon Steel AISI 1040 material if the temperature of the secondary water in WCT is less than 90 ° C. The primary water operating temperature is a maximum of 90 ° C and the secondary water temperature does not reach 90 ° C due to heat transfer from primary to secondary. Translational displacement that occurs is very small when compared to the WCT dimension so that it does not result in a change in shape in the WCT. Thus the design of the WCT can be continued to be constructed and safely operated.

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Analisis kekuatan mekanik water cooling tank pada fasilitas uji untai passif-02 menggunakan catia

ANALISIS KEKUATAN MEKANIK DESAIN BEJANA MOLECULAR SIEVE . Reaktor Daya Eksperimental (RDE) menggunakan bahan bakar bola ( pebble ) dan gas helium sebagai pendingin primernya. Untuk mempertahankan dan menjaga kualitas helium sebagai pendingin sesuai persyaratannya maka dirancang fasilitas Sistem Pemurnian Helium (SPH). Salah satu bagian dari komponen utama fasilitas Sistem Pemurnian Helium ini adalah bejana molecular sieve. Fungsi dari molecular sieve ini untuk menyerap gas CO 2 , CH 4 , dan H 2 O. Tujuan penelitian ini adalah untuk mengetahui kemampuan kekuatan mekanik dari bejana molecular sieve melalui simulasi menggunakan software Computer Aided Three-dimensional Interactive Application (CATIA). Tahapan yang dilakukan dalam menganalisis kekuatan mekanik desain molecular sieve meliputi : pembuatan model 3-dimensi, memasukkan data sifat mekanik material SS304, serta mensimulasikan pengoperasian pada tekanan uji dan temperatur bervariasi. Pada tekanan 30 bar dan temperatur 120 °C tegangan mekanik yang dihasilkan sebesar 4,4608 x 10 7 N/m 2 lebih kecil daripada yield strenght material SS 304 dan berada di daerah elastis material. Sedangkan translational displacement sebesar 1,1375 mm sangat kecil jika dibandingkan dengan dimensi bejana molecular sieve sehingga tidak mengakibatkan perubahan bentuk. Dengan demikian bejana molecular sieve aman untuk dioperasikan guna mendukung penelitian pemurnian helium Kata kunci: bejana molecular sieve , tegangan mekanik, translational displacement, CATIA

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Analisis kekuatan mekanik desain bejana molecular sieve

Closed-loop experimental investigation of single-phase natural circulation flow phenomena based on temperature and heating power variations

In the future, the use of passive cooling system without electrical power input become highly considered to be implemented in the design of nuclear reactor safety system. Moreover, the lessons learned from the Fukushima-Daiichi accident encourage the incorporation of such passive cooling system. The passive safety cooling system is aimed to cope with both design bases as well as severe accidents. The natural circulation is one example parameter of the passive cooling system features being widely considered. However, some of the parameters involving in natural circulation are still being investigated, in particular the problem of flow instability. BATAN is designing a large-scale test loop facility, named FASSIP-02 loop, with a height of 11 meters between a heat source and a cooling source. The FASSIP-02 loop is designed to simulate the residual heat in the reference reactor. To ensure the validity of the design prior to the construction, it is necessary to make an analytical calculation using some correlations to estimate the natural circulation flow rate. The calculation method is performed by using the derived two principle correlations of the buoyancy force in the heating section and the gravitational force on the cooling section. The water temperatures in the heating section are varied at 50°C, 60°C, 70°C, 80°C and 90°C with the water temperature in the cooling tank pool are varied at 10°C, 20°C, 30°C, 40°C and 50°C. The calculation results can estimate the water temperature and volume are required. In addition, it could be used to determine the experimental matrix that is based on the FASSIP-02 loop design.

https://iopscience.iop.org/article/10.1088/1755-1315/105/1/012091/pdf

Estimation of natural circulation flow based on temperature in the FASSIP-02 large-scale test loop facility

The natural circulation is considered in the design of emergency passive core cooling system in a nuclear power plant. In that context, in order to investigate the characteristics of the natural circulation, FASSIP-02 experimental loop is designed. This paper simulates the various operational conditions with different condition of the heater power, the pipe insulation and the expansion tank's valve using RELAP5 code. The objective is to obtain the best operational conditions of FASSIP-02 once it is built. The simulation results show that the until 50,000 s the steady state condition could not be achieved yet when the heater power greater than 10 kW. The pipe insulation reduced the heat loss to the environment and in turn it causes faster increase of the water temperature inside the pipe. While, if the expansion tank's valve is closed during the operation, the pressure inside the loop would increase, faster when the heater power is higher. It is concluded that in all cases to avoid the saturation condition, the heater power should be maintained lower than 10 kW, especially when the loop pipe is insulated.

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Simulation of Operational Conditions of Fassip-02 Natural Circulation Cooling System Experimental Loop

As in many other energy generating system, in the nuclear power plant, the use of natural circulation principle for the safety system is increasingly considered. The natural circulation could play an important role in providing emergency cooling of the nuclear reactor. The reliability of the use of natural circulation in the nuclear power plant should be demonstrated in order to assure the level of its safety. FASSIP-02 is a large scale test facility to study the natural circulation in the safety system of a nuclear power plant. To study the characteristics of the natural circulation and to help validating the design of FASSIP-02, a numerical study using RELAP5 code is undertaken. Based on the existing design of FASSIP-02, the numerical simulation is done with two variables, i.e. the heat flux and the pipe diameter. The effect of heat transfer surface area for dissipating the heat is also studied. The results show the natural circulation established in the FASSIP-02. The characteristics of the natural circulation with the values of several important parameters such as temperature, mass flow rate and pressure in the loop are obtained. The RELAP 5 calculations have provided the results that could be used to support the design and future operation of FASSIP-02.

http://iopscience.iop.org/article/10.1088/1755-1315/105/1/012090/pdf

Numerical study on natural circulation characteristics in FASSIP-02 experimental facility using RELAP5 code

A better understanding on the phenomenon of natural circulation flow for cooling systems is necessary prior to improving the safety of nuclear power plant, not only in normal operation but also in accident conditions. One way to understand this phenomenon is by analyzing the Nusselt number in various geometrical dimensions through experimentation. The purpose of this study is to understand natural circulation phenomenon in transient condition by varying height differences between heater and cooler. To achieve this purpose, an experiment apparatus called NC-Queen was developed and arranged to enable three variations of height differences between heater and cooler, i.e ., 1.4 m, 1.0 m, and 0.3 m. It is made of a stainless steel tube with a diameter of 1 inch, arranged in rectangular shape 6.4 m in length, and uses water as coolant. The initial temperature of the heater was set at 90 °C. The Nusselt number was obtained by calculating the flow rate as a function of transient temperature. The results confirm that height differences affect thermal properties and flow region based kinetics characteristics of water. In initial condition, decreasing height difference from 1.4 m to 1.0 m resulted in flow rate reduction of 16.7 %, while decreasing height difference from 1.4 m to 0.3 m resulted in a 39.1 % flow rate reduction. In final condition, the flow rate reductions were 75 % and 82.6 %, respectively. Meanwhile, in initial condition, the Nusselt number for height difference reduction from 1.4 m to 1.0 m and from 1.4 m to 0.3 m decreased by 30.5 % and 74.6 %, respectively, while for final condition, the Nusselt number decreased by 11.9 % and 67.4 %, respectively. The new constants in relationship between Nusselt number and the height difference are a = 20.06 and b = 0.56. The dominance of turbulent flow provides a good safety margin with indications of the large amount of heat released.

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An Experimental Analysis on Nusselt Number of Natural Circulation Flow in Transient Condition Based on the Height Differences Between Heater and Cooler

DH Dedy Haryanto

Papers

Estimation of natural circulation flow based on temperature in the FASSIP-02 large-scale test loop facility

Simulation of Operational Conditions of Fassip-02 Natural Circulation Cooling System Experimental Loop

Numerical study on natural circulation characteristics in FASSIP-02 experimental facility using RELAP5 code

An Experimental Analysis on Nusselt Number of Natural Circulation Flow in Transient Condition Based on the Height Differences Between Heater and Cooler

Analisis kekuatan mekanik water cooling tank pada fasilitas uji untai passif-02 menggunakan catia