Effect of Coolant Water Temperature of Emergency Core Cooling System on Failure Probability of Reactor Pressure Vessel

Structural integrity assessment of reactor pressure vessel (RPV) is important for the safe operation of nuclear power plant. For an RPV in a pressurized water reactor (PWR), pressurized thermal shock (PTS) resulted from rapid coolant water injection due to a loss-of-coolant accident is an issue of particular concern. The coolant water temperature in the emergency core cooling system (ECCS) can influence the integrity of RPV subjected to PTS events; thus, this paper is focused on investigating the effect of coolant water temperature of ECCS on failure probability of an RPV. First, thermal-hydraulic (TH) analyses were conducted for a Japanese PWR model plant by using RELAP5, and different coolant water temperatures in ECCS were considered to investigate the effect of coolant water temperature on TH behaviors during a PTS event. Using the TH analysis results, probabilistic fracture mechanics (PFM) analyses were performed for the RPV of the Japanese model plant. Based on the PFM analysis results, the effect of coolant water temperature on failure probability of the RPV was quantified.

Effect of Coolant Water Temperature of ECCS on Failure Probability of RPV

For reactor pressure vessels (RPVs) of pressurized water reactors, temperature of the coolant water in the emergency core cooling system (ECCS) may influence the structural integrity of the RPV during pressurized thermal shock (PTS) events. By focusing on a mitigation measure to raise the coolant water temperature of ECCS for aged RPVs to reduce the effect of thermal shock due to PTS events, we performed thermal hydraulic analyses and probabilistic fracture mechanics analyses by using RELAP5 and PASCAL4, respectively. The analysis results show that the failure probability of RPV decreased dramatically when the coolant temperature in accumulator as well as in the high- and low-pressure injection systems (HPI/LPI) was increased, although the increase in coolant temperature in the HPI/LPI only did not lead to a decrease in the failure probability.

PENGARUH KECEPATAN ALIRAN FLUIDA TERHADAP CAPAIAN SUHU OPTIMAL HASIL RANCANGAN COOLBOX ZERO POLLUTION

Pemanfaatan teknologi telah merambah dalam semua aspek kehidupan manusia, salah satunya teknologi pada bidang peralatan rumah tangga . Household appliances adalah salah satu contoh teknologi yang terus berkembang mengikuti kebutuhan manusia akan berbagai factor seperti, kemudahan, keandalan kenyamanan, ekonomi, dan sebagainya. Ini terlihat pada penjualan lemari es yang terus meningkat ditiap tahunnya. Namun perkembangan mesin pendingin masih belum sempurna karena masih terdapat kekurangan dilihat dari digunakannya bahan kimia yang kurang ramah lingkungan seperti Freon. Maka dari itu penulis berkeinginan untuk merancang dan meneliti Coolbox Zero Pollution yang tidak menggunakan Freon. Penelitian ini bertujuan untuk mengoptimalkan unjuk kerja dari Coolbox Zero Pollution dan mengetahui pengaruh kecepatan aliran fluida terhadap suhu yang dicapai Coolbox Zero Pollution. Dari hasil penelitian didapatkan penggunaan kecepatan aliran 0,033 m/s perbandingan suhu fluida radiator coolant, air + radiator coolant, dan air adalah 12,180C : 12,450C : 13,420C. Pada penggunaan kecepatan aliran 0,049 m/s perbandingan suhu fluida radiator coolant, air + radiator coolant, dan air adalah 11,630C : 12,110C : 13,060C. Pada penggunaan kecepatan aliran 0,071 m/s perbandingan suhu fluida radiator coolant, air + radiator coolant, dan air adalah 11,170C : 11,620C : 12,470C.Kata Kunci : coolbox, peltier, pompa, fluida, suhu, pendingin Utilization of technology has penetrated in all aspects of human life, one of them technology in the field of household appliances. Household appliances is one example of technology that continues to grow following human needs for various factors such as convenience, comfort, economy, reliability, and so on. This is seen in the sales of refrigerators that continue to increase each year. However, the development of the cooling machine is still not perfect because there are still deficiencies seen from the use of less environmentally friendly chemicals such as Freon. Therefore the author intends to design and examine Coolbox Zero Pollution which does not use Freon. This study aims to optimize the performance of Coolbox Zero Pollution and to know the effect of fluid flow velocity on temperature reached by Coolbox Zero Pollution. From the result of the research, the use of flow velocity of 0.033 m / s temperature ratio of fluid radiator coolant, water + radiator coolant, and water is 12,180C: 12,450C: 13,420C. At a flow rate of 0.049 m / s the temperature ratio of the fluid radiator coolant, water + radiator coolant, and water is 11.630C: 12.110C: 13.060C. At a flow rate of 0.071 m / s the temperature ratio of the fluid radiator coolant, water + radiator coolant, and water is 11,170C: 11,620C: 12,470Ckeyword : coolbox, peltier, pump, fluid, temperature, cooler

Boric Acid Radiolysis in Primary Coolant Water of PWR at Temperature of 250oC

BORIC ACID RADIOLYSIS IN PRIMARY COOLANT WATER OF PWR AT TEMPERATURE OF 250oC. The existence of oxygen in the primary coolant system of PWR could lead to corrosion, hence it is very important to suppress the oxygen concentration in the system. Therefore, study of the effect of boric acid addition into the primary coolant water system of PWR to suppress oxygen concentration resulted from gamma-ray radiation is essential to be performed. The aim of this research is to understand reaction mechanism at temperature of 2500C and the effect of boric acid adding toward oxygen concentration in the PWR primary coolant water. Methodology used is simulation using Facsimile software. Input for the software namely radiolysis reaction mechanism for pure water, G value from radiolysis product, dose rate of 1 and 104 Gy/s, aeration and deaeration system, and specific reaction of boric acid with hydroxyl radical and hydrated electron at temperature 250C and 3000C. The output are in the form of irradiation time vs oxygen concentration time series. The results show that the oxygen production increase significantly with the irradiation time and reach the saturated concentration at 107s. Based on the plot of oxygen’s concentration at 107s vs boric acid, several results are as following: oxygen concentration significantly suppressed by boric acid addition and gives the exponential decreasement, the higher dose rate gives the higher concentration of oxygen, the aeration system gives no effect on suppressing oxygen concentration at boric acid addition up to 0.1M.

Electrochemical degradation tests on a carbon-black-filled ethylene propylene diene monomer rubber under tensile strain

Rubber hoses play an important role as a path for carrying the coolant liquid between the radiator and the automotive engine. However, the rubber hoses are apt to deteriorate because of the formation of a galvanic circuit between the rubber hose, the coolant water and the fitting metal part of the engine. Such electrochemical degradation can damage the inner skin of the hose in contact with the coolant liquid heated by the working engine, which often leads to leakage of the coolant water and thereby to hose failure. An ethylene propylene diene monomer rubber has mostly been utilized as the material for the coolant hoses of automotive engines because of the strong resistance to various environmental stresses. This study conducted experimental simulation tests and evaluation of the electrochemical degradation behaviours of the carbon-black-filled ethylene propylene diene monomer rubber used for the coolant hoses. The tests were performed by considering the actual circumstances together with the combined thermal, tensile strain and electrostatic voltage loadings on the rubber hoses. The behaviour of the change in the electrical resistance of a specimen and, thus, the apparent decrease in the current were analysed quantitatively. An Arrhenius life prediction by using the decrease in the current was reasonably expressed for the accelerated life tests. Many microhole networks were thus formed in the skin part of the specimen by the microbreaks in the carbon-black phase and the scission of the sulphur cross-links. The coolant liquid penetrated significantly into the skin, which resulted in a considerable swelling of the skin. The larger the strain application to the rubber, the lower are the strength and the elongation at the breaking point. An exponential index parameter can represent quantitatively the behaviours of the decreases in the mechanical properties used for accurate life prediction.