No abstract

During the operation of the research reactor RSG-GAS, there are many design parameters should be verified based on postulated accidents. Several design basis accidents (DBA) such as loss of flow accident (LOFA) and reactivity-initiated accident (RIA) also have been conducted separately. This paper discusses about possibility of simultaneous accidents of LOFA and RIA. The accident analyses carry out calculation for transient condition during RIA, LOFA, and postulated accident of simultaneous LOFA-RIA. This study aims to conduct a safety analysis on simultaneous LOFA and RIA, and investigate the impact on safety margins. The calculations are conducted by using the PARET code. The maximum temperature of the center fuel meat at nominal power of 30 MW and steady state conditions is 126.10°C and MDNBR of 2.94. At transients condition, the maximum center fuel meat temperature for LOFA, RIA and simultaneous LOFA-RIA are consecutively 132.99°C, 135.67°C and 138.21°C, and the time of reactor trip are 3.2593s, 3.6494s and 2.7118s, respectively. While the MDNBR for LOFA, RIA and simultaneous LOFA-RIA are respectively at transient condition are 2.88, 2.58 and 2.63, respectively. It is shown that, simultaneous LOFA-RIA has the fastest trip time. In this case, the low flow trip occurs first in advance to over power trip.  From these results, it can be concluded that the RSG-GAS has adequate safety margin against transient of simultaneous LOFA-RIA.Keywords: RSG-GAS, Simultaneous, LOFA, RIA, PARET

A COMPARISON IN THERMAL-HYDRAULICS ANALYSIS OF PWR-1000 USING FIXEDAND TEMPERATURE FUNCTION OF THERMAL CONDUCTIVITY. A study to analyze theinfluence of the fuel-cladding’s thermal conductivity on the sub-channel of pressurized waterreactor 1000 (PWR-1000) using COBRA-EN computer code was conducted. The purpose ofthis research is to gain complete understanding of sub-channel thermal-hydraulic aspectsrelated to fuel performance, especially the appropriate range of thermal conductivity of UO2fuel (kf) and zircaloy-4 cladding (kc) in order to obtain an accurate sub-channel analysisrelated to its safety behavior. The research was conducted by comparing the calculation withthe combination values of the fixed kf and kc, as well as the calculation using kf and kc astemperature function. The fixed kf using in this calculation were 5.26 W/m.K, 3.85 W/m.K,3.60 W/m.K, 3.18 W/m.K, 2.90 W/m.K, 2.53 W/m.K and 2.34 W/m.K, while the kc were13.0 W/m.K, 15.57 W/m.K, 16.75 W/m.K, 17.94 W/m.K and 18.69 W/m.K. The maximumfuel center linet emperature using kf and kca s temperature function (MATPRO) for hot sub -channel was 1717.65°C and taken as the reference in accepting the calculation result usingfixed thermal conductivity. The analysis was accepted, if the deviation between bothtemperature was in the range of -10% to 10%. This analysis results for hot sub-chan nelwas accepted for the calculation using value of kf in the range of 3.18 - 2.90 W/m.K for allall variation value of kcW. hile the calculation using value of koff 2.53 W/m.K was accepet dfor value of kc in the range of 16.76 - 18.69 W/m.K

ABSTRAKOPTIMASI DESAIN TERMOHIDROLIKA TERAS DAN SISTEM PENDINGIN REAKTOR RISET INOVATIF DAYA TINGGI. Implementasi reaktor inovasi telah diterapkan pada berbagai reaktor riset baru yang saat ini sedang dibangun. Pada saat ini BATAN sedang merancang desain konseptual reaktor riset daya tinggi yang telah masuk pada tahap optimasi desain. Spesifikasi desain konseptual reaktor riset inovatif adalah reaktor tipe kolam berpendingin air dan reflektor D 2 O. Teras reaktor memiliki kisi 5x5 dengan 16 bahan bakar dan 4 batang kendali. Teras reaktor berada di dalam tabung berisi D 2 O yang berfungsi sebagai posisi iradiasi. Daya reaktor 50 MW didesain untuk membangkitkan fluks neutron termal sebesar 5x10 14 n/cm 2 s. Teras reaktor berbentuk kompak dan menggunakan bahan bakar U 9 Mo-Al dengan tingkat muat uranium 7-9 gU/cm 3 . Desain termohidrolika yang mencakup pemodelan, perhitungan dan analisis kecukupan pendingin dibuat sinergi dengan desain fisika teras agar keselamatan reaktor terjamin. Makalah ini bertujuan menyampaikan hasil analisis perhitungan termohidrolika teras dan sistem reaktor riset inovatif pada kondisi tunak. Analisis dilakukan menggunakan program perhitungan yang telah tervalidasi, masing-masing adalah Caudvap, PARET-ANL, Fluent dan ChemCad 6.4.1. Hasil perhitungan menunjukkan bahwa pembangkitan panas yang tinggi dapat dipindahkan tanpa menyebabkan pendidihan dengan menerapkan desain teras reaktor bertekanan, di samping itu desain awal komponen utama sistem pembuangan panas yang terintegrasi telah dilakukan, sehingga konseptual desain termohidrolika RRI-50 dapat diselesaikan.Kata kunci : reaktor riset inovatif, Caudvap, PARET-ANL, Fluent, ChemCad 6.4.1. ABSTRACT THERMALHYDRAULIC DESIGN AND COOLING SYSTEM OPTIMIZATION OF THE HIGH POWER INOVATIVE RESEARCH REACTOR. Reactor innovation has been implemented in a variety of new research reactors that currently are being built. At this time BATAN is designing a conceptual design of the high power research reactor which has entered the stage of design optimization. The conceptual design specifications of the innovative research reactor is a pool type reactor, water-cooled and reflected by D 2 O. The reactor core has a 5 x 5 grid with 16 fuels and 4 control rods, which is inserted into a tube containing