Hasil Pencarian  ::  Simpan CSV :: Kembali

Abstrak :
Strong market demand and uncontrolled exploitation and/or the inadequate management of fisheries have caused many stocks of sea cucumbers to be overexploited. One suggested effort to overcome this problem is sea ranching. Stocking density is the most important consideration in sea cucumber rearing; therefore, this present work is aimed at elucidating the best stocking density for sea ranching of Holothuria atra. H. atra was taken from the Panjang Island, Jepara waters and reared in bottom cages in Teluk Awur waters, Jepara with a density of 30, 20, or 10 individuals per cage measuring 2 m × 2 m × 1.8 m (with bottom area of 4 m2). Stocking times of H. atra were at the initial time of cage installation, the second and the third months after installation. Bottom sediment characteristics (i.e., chlorophyll a, b, phaeophytin, and total carotene) of the sea cucumber habitat and water quality in the cages were measured monthly during the study. The results showed that growth of H. atra fluctuated; low stocking density yielded a higher weight gain than high stocking density did. The highest weight gain was present in the density of 10 individuals/cage in the second stocking month. The highest survival rate of H. atra was seen in the condition of 30 individuals/cage (93%) at the third stocking month, which means that these sea cucumbers were only reared for three months. The highest mortality occurred at a density of 20 individuals/cage with the survival rate being low (45%) at the first stocking time or in the fifth month of rearing. There was fission evidence among H. atra reared in the cages, resulting in smaller organisms. Among the water quality parameters, the concentration of chlorophyll a, b, phaeophytin, and carotene in the sediment fluctuated according to the time of sea cucumber rearing caused by their feeding and bioturbation. The study results suggested to stock H. atra at low density during the second stocking month to get higher growth.

Abstrak :
Determination of gamma emiter radionuclides impuritis in 99Mo fission products of llow enriched uranium. Determination of the gamma emitter radionuclides impuritis in 99Mo fission produc from low enriched uranium (LEU) by lod-thio extraction methods was carried ourt...

Abstrak :
Reaktor tipe HTGR merupakan reaktor berpendingin gas temperatur tinggi (~900°C). Terdapat 2 tipe elemen bakar HTGR yaitu praismatik dan pepple bed. Kedua tipe elemen bakar tersebut tersusun dari partikel berlapis TRISCO yang terdiri dari lapisan IPyC, SiC, dan OPyC yang berfungsi sebagai pengungkung produk fisi dan menjaga integritas bahan bakar. Reaktor beroperasi dengan temperatur tinggi, sehingga kinerja/kemampuan bahan bakar dalam menajan produk fisi perlu diketahui. Tujuan studi adalah untuk memperoleh pemahaman tentang karakteristik produk fisi yang dihasilkan bahan bakar, karakteristik penghalang dan kinerja bahan bakar dalam menahan produk fisi. Metode yang digunakan adalah kajian dan analisis dengan mengevaluasi kemampuan penghalang (barrier) dalam menahan produk fisi pada elemen bakar primatik dan pebble. Hasil studi menunjukkan bahwa terdapat beberapa mekanisme beberapa produk potensial lepasnya produk fisi, yaitu: difusi melalui lapisan, kerusakan lapisan, korosi SiC oleh produk fisi palladium dan dekomposisi termal SiC. Bahan bakar merupakan penghalang pertama terhadap beberapa mekanisme potensial lepasnya radionuklida produk fisi sedangkan lapisan SiC merupakan penghalang utama yang menahan sebagian besar produk fisi gas dan padat pada temperatur operasi normal (< 1250°C).

Abstrak :
ABSTRAK
Nuklir adalah salah satu sumber energi baru yang patut dipertimbangkan untuk memenuhi kebutuhan energi nasional. Penggunaan bahan nuklir berbasis thorium oksida ThO2 telah dikembangankan oleh beberapa negara maju sebagai bahan bakar nuklir untuk mengurangi dan menggantikan pemakaian uranium yang banyak digunakan sebagai bahan bakar untuk pembangkit listrik tenaga nuklir PLTN di dunia. Pada saat ini Batan Tenaga Nuklir Nasional BATAN berusaha merancang suatu reaktor daya eksperimental RDE dari turunan reaktor tipe High Temperature Gas-cooled Reactor HTGR . Reaktor nuklir tipe HTGR mempunyai dua bentuk bahan bakar yaitu prismatik dan bola pebble . RDE yang akan dikembangkan di Indonesia mempunyai bahan bakar uranium dan atau thorium berbentuk bola. Dalam penelitian ini dilakukan pemodelan dan simulasi panas pembangkitan oleh reaksi fisi yang disebabkan oleh neutron, dan perpindahan panas antara bahan bakar bentuk pebble dengan media pendingin gas helium pada reaktor daya eksperimental. Analisis neutronik dan termal-aliran dalam teras RDE seperti ini belum pernah dilakukan di Indonesia. Tujuan dilakukannya penelitian ini adalah untuk memperoleh desain teras yang aman pada kondisi neutronik yang kritis dari teras RDE. Pemodelan dan simulasi transport partikel neutron untuk analisis pembangkitan panas reaksi fisi dilakukan dengan perangkat lunak berbasis metoda monte carlo-MCNP, dan untuk fenomena transport dalam proses pendinginan RDE dilakukan dengan perangkat lunak komputasi dinamika fluida FLUENT 6.3. Teras aktif RDE dimodelkan dengan geometri silinder berdiameter 180 cm dan tinggi 197 cm. MCNP dapat memodelkan struktur geometri bahan bakar bola dalam teras reaktor RDE dengan baik untuk mensimulasikan transport neutron dan distribusi reaksi fisi. Aliran pendingin gas helium melalui bola-bola bahan bakar dalam teras reaktor dimodelkan sebagai aliran fluida dalam medium berpori. Tiga mode perpindahan panas dan aliran turbulen pendingin dimodelkan dalam proses pendinginan. Dari pemodelan dan simulasi neutronik diperoleh nilai kritikalitas keff =1.0921 dan densitas daya yang dihasilkan sebesar 2.03 watts/cm3. Hasil ini kemudian dimasukkan dalam pemodelan proses pendinginan dan aliran fluida dalam teras RDE sehingga menghasilkan temperatur maksimum pendingin gas helium sebesar 970.32K. Kritikalitas neutronik keff lebih dari satu, tetapi tak melebihi 1,3 dan kondisi termal teras menunjukkan bahwa desain teras RDE sangat aman.

---

ABSTRACT
Nuclear is one of new energy sources that should be considered to meet national energy demands. The usage of Thorium Oxide ThO2 based nuclear fuel has been developed by some developed countries to reduce and replace Uranium that was commonly used as nuclear fuel for nuclear power plants in the world. Nowdays, BATAN is trying to design an experimental power reactor RDE which is the derivative type of High Temperature Gas cooled Reactor HTGR . HTGR has two types of fuel i.e. Prismatic and Pebble. RDE, which will be developed in Indonesia uses spherical uranium and or thorium as its fuel. This research performs modeling and simulation of fission heat generation caused by neutronas well heat transfer between fuel pebble and helium gas as cooling medium in the experimental power reactor. This thermal flow analysis in the RDE core has never been conducted in Indonesia. The objective of this study is to obtain a safe reactor core design in critical neutronic condition of the RDE core. Modeling and simulation of neutron particle transport for fission heat generation analysis were conducted using a software based on Monte Carlo method MCNP, and for the transport phenomena in the cooling process of RDE was conducted using computational fluid dynamics software FLUENT 6.3.26. RDE active core was modeled using cylindrical geometry with a diameter of 180 cm and 197 cm high. MCNP can model the geometrical structure of the Pebble fuel within the RDE core properly to simulate neutron transport and distribution of fission reaction. Flow of helium gas coolant through the pebble fuel in the reactor core was modeled as a fluid flow in a porous medium. Three types of heat transfer and turbulent coolant flow were modeled in the cooling process. Results obtained from Neutronic modeling and simulation i.e. criticality values of 1.0921 keff and average power density of 2.03 watts cm3. These results were later inserted into the cooling process and fluid flow modeling in the RDE core, so that generate the maximum temperature of the coolant helium gas at about 970.32 K. Neutronic criticality more than one, but not exceeding 1.3 and the core thermal conditions showed that the design of the RDE core is very safe.

Abstrak :
The power makers ? challenge : and the need for fission energy looks at why using only conventional renewable energy sources is not quite as simple as it seems. Following a general introduction to electricity and its distribution, the author quantifies the reductions needed in greenhouse gas emissions from the power sector in the face of ever increasing world demands for electricity. It provides some much needed background on the many energy sources available for producing electricity and discusses their advantages and limitations to meet both the emission reduction challenge and electricity demand. By analyzing the three main groups of energy sources, renewable energy, fossil fuels and fission energy (nuclear power), readers can assess the ability of each group to meet the challenge of both reducing emissions and maintaining reliable supply at least cost. It is written for both non-technical and technical readers.