PENENTUAN WAKTU TRANSPORT NITROGEN-16 e6N)DI KOLAM REAKTOR SERBA GUNA "G. A. SIWABESSY

PENENTUAN WAKTU TRANSPORT NITROGEN-16 e6N) DI KOLAM REAKTOR SERBA GUNA "G. A. SIWABESSY". Dalam penelitian ini diasumsikan reaktor mula-mula beroperasi normal pacta tingkat daya nominal 30 MWtip kemudian terjadi gangguan yang menyebabkan pompa primer RSG-GAS (1EOl) mati, reaktor pancung daB sistem lapisan air hangar (KBE02) tidak berfungsi. Dengan debit air nominal sebesar Q = 0,86 Mgralll/detik (SAR), beda suhu inlet daBoutlet teras adalah 6.T - 8,33 DC (SAR = 8,70 DC). Suhu inlet teras sama dengan suhu pennukaan kolam reaktor. Dalam perhitungan konservatif diandaikan T;',= 40,2 DC(= SAR) dan Toot= 48,53 DC(SAR = 48,90 DC). Perbedaan suhu antara kedua tempat pengamatan yang terpisahkan sedalalll H - 1055 cm ini (SAR = 1000 cm) menimbulkan perbedaan rapat massa air, yaitu Pd = 0,9921 g/cm3 (air permukaan, dingin) dan Pp = 0,9887 g/cm3 (air kedalaman, panas). Karena Pd > Pp, maka air kedalaman (lebih panas) akan mengapung naik ke permukaan. Atom-atom betas 16NdaB molekul-molekul senyawa nitrogen lain yang mengandung 16Nyang terbentuk dari proses aktivasi 160 menurut reaksi nuklir endoergik 160(n,p)16Ndan terlarut dalam air kedalalllan yang panas dengan Pp < Pd, akan naik secara global ke permukaan karena adanya gaya apung Ft. Adanya kekentalan air, 11= 0,6506 mPa'det (padaTu.)' maka gerakan air panas ke alas akan lllengalami gaya hambat n karena adanya gesekan dengan molekul-molekul air dingin di sekitarnya. Besarnya gaya gesek ini sebanding dengan kuadrat kecepatannya. Berdasarkan besaran-besaran fisis dan teknis yang diketahui, termasuk percepatan gravitasi bumi setempat, maka kecepatan terminal vp dapat ditentukan sebesar 25,59 cm/detik dan waktu transport 16Nt" terhitung sebesar 46,42 detik. Pada saat itu, konsentrasi 16N telah meluruh menjadi - 1% dibandingkan aktivitas semula di kedalaman teras. Dengan diperolehnya waktu transport radionuklida ini bisa ditentukan konsentrasi 16Ndi permukaan kolam reaktor yang dapat digunakan sebagai bahan asupan guna mengevaluasi keselamatan radiasi serta unjuk kerja sistem lapisan air hangat.
ABSTRACT DETERMINATION OF TRANSPORT TIME FOR NITROGEN-16 e6N) IN REACTOR POOL OF MULTIPURPOSE REACTOR "G. A. SIWABESSY". The investigation reported in this paper was assumed that the reactor in early normal operation condition on 30 MW thermal power. Then happened a disturbance cause the primary cooling pumps system (1EO1) was loss of electrical power and warm water layer system (KBE02) located under surface of pool water of MPR-GAS was no function. On this level of power, nominal debit of cooling water according to SAR was 0.86 Mgram/sec, then the different of the inlet and outlet temperatures was 6.T - 8.33 DC (SAR = 8.70 DC). The core inlet temperature was the same with the temperature of the surface water. In this conservatively calculation was assumed Tu!= 40,2 DC (= SAR) and Tau= 48,53 DC(SAR = 48,90 DC).The different temperatur of the both different location points separated by H - 1055 cm deep of water (SAR = 1000 cm) caused the different in the water density. The density of surface water was 0,9921 g/cm3 and the deepth water density was 0,9887 g/cm3. Because Pdgreather than Pp' the warmer deepth water will buoyance to surface of the pool. Free atoms and molecules of 16Nfomled and saluted in tlle deep primary water will bouyance up to surface of pool water globaly by bouyance force. Due to water viscosity, 11= 0,6506 mPa'det (onTu.)'during up ward movemet it would be hold by the drag force n, caused by friction with molecoles of cold water at the vicinity. The drag force was proportional directly to quadrat of it velocity. If the given debit of primary water, the transit tinle of water in the core, global volume of hot water, equivalence sphere radius and acceleration of gravitation were known, the terminal velocity and the transport time of 16Ncan be determined together, there were vp = 25,59 cm/sec and t" = 46,42 sec respectively. After the transport time of this radionuclide was determined, the radioactivity concentration of 16Nat the surface of water pool of MPR-GAS culd be use to evaluate radiation safety and performance of warm water layer system.