Analysis of the TRIGA 2000 core reshuffling scenario based on fuel burn-up and fuel density has been done. One of the requirements of Bandung TRIGA 2000 Reactor reliability is the implementation of maintenance and surveillance activities with predetermined Operation and Limits Conditions (OLC) so that the safety parameters will be met. Core management is one of the maintenance activities carried out. Safety parameters that are required to be fulfilled in the core management include the shutdown margin and the power peaking factors. The scenario carried out in the core management in this analysis that was doing the core compaction by sorting the fuel position on the core based on the fuel burnup and the fuel density. Each core management method was carried out in 4 scenarios. The purpose of this analysis is of course to compare both methods and also to get the optimal scenario to be applied to the core of the existing Bandung TRIGA 2000 Reactor. From the eight proposed scenarios, obtained two scenarios that meet the requirements of shutdown margin and power peaking factor from the OLC, namely scenario 2 with the k-eff value obtained 1.01243, and scenario D with the k-eff value obtained 1.02031. Therefore, scenarios 2 and D will then be proposed as the existing Bandung TRIGA 2000 Reactor core configuration scenario.

ABSTRAK ANALISIS KONVEKSI ALAM TERAS REAKTOR TRIGA BERBAHAN BAKAR TIPE PELAT MENGGUNAKAN COOLOD-N2.Rencana penghentian produksi elemen bakar jenis TRIGA oleh produsen elemen bakar reaktor TRIGA, sudah seharusnya diantisipasi oleh badan pengoperasi reaktor TRIGA untuk menggantikan elemen bakar tipe silinder tersebut dengan tipe pelat yang tersedia di pasaran. Pada penelitian ini dilakukan perhitungan untuk model teras reaktor dengan spesifikasi utama menggunakan bahan bakar U 3 Si 2 Al dengan pengayaan uranium sebesar 19,75% dan tingkat muat 2,96 gU/cm 3 . Analisis dilakukan menggunakan program COOLOD-N2 yang tervalidasi pada konfigurasi teras TRIGA konversi berbahan bakar tipe pelat, yang tersusun atas 16 elemen bakar, 4 elemen kendali dan 1 fasilitas iradiasi yang terletak tepat di tengah teras. Hasil analisis menunjukkan bahwa dengan temperatur pendingin masuk ke teras sebesar 37 o C, dan rasio faktor puncak daya radial ≤ 1,92 maka daya maksimum yang dapat dioperasikan pada moda operasi konveksi bebas adalah 600 kW. Karakteristik termohidrolika yang diperoleh antara lain adalah temperatur pendingin di sisi outlet, kelongsong dan meat masing-masing sebesar 82

National Nuclear Energy Agency has planned to convert the Bandung TRIGA reactor by replacing the rod-type into plate-type fuel elements. The calculation results show that Bandung TRIGA Plate reactor with 2000 kW power requires forced convection cooling system. According to the calculation results using the Coolod-N2 computer program the minimum required cooling flow rate is 70 kg/s. Consequently, it is necessary to modify the reactor primary cooling system. In this modification required a flapper valve design that can a double function. The valve closed when the primary pump is powered and the flow rate on the primary coolant is 70 kg/s. However, when the pump is off because of the power outages and the reactor will scram, so the flapper valve will open. The residual heat in the reactor core will be cooled by natural convection. There is reversal flow from a downward to an upward cooling direction, and the upward natural convection heat removal throughout the flapper valve. In addition, the reactor also will scram if the cooling flow rate drops below 85% of 70 kg/s. The flapper valve is equipped with a ballast pendulum to open the flapper valve. The pendulum load must be greater than the flapper valve force plus the pump force due to forced flow. The flapper valve will open, if the flow rate is smaller than 85% of the required flow. Conversely, the flapper valve load must be smaller than the amount of flapper valve force and flow due to the pumps attractiveness, so that the flapper valve can be closed tightly and the reactor can operate with a forced convection flow. The design of natural convection flapper valve considers the following of a reliable, a work based on passive systems, a simple, an easy to make, an easy maintenance and it can be observed from the top of the reactor tank deck. As a redundancy, the operation of natural convection a flapper valve is added by mechanical operation, so the operation of the valve is truly reliable.