Analisis Reaktivitas Batang Kendali dan Distribusi Fluks Neutron pada Hydride Microreactor

RAYHAN ALGHIFFARI A, Dr. Ir. Andang Widi Harto, MT.; Dr.-Ing. Ir. Sihana

2023 | Skripsi | S1 TEKNIK NUKLIR

Nuklir merupakan salah satu sumber energi yang dapat digunakan untuk mengurangi emisi karbon. Pengembangan Reaktor nuklir mengarah pada desain yang lebih kecil, lebih aman, dan lebih ekonomis seperti Small Modular Reactor dan Microreactors. Penelitian ini akan melakukan analisis terhadap beberapa parameter keselamatan utama dari desain hydride microreactor sesuai dengan standar International Atomic Energy Agency (IAEA). Parameter tersebut yaitu shutdown margin, PPF (power peaking factor), dan reaktivitas batang kendali. Reaktor dimodelkan dalam kode simulasi openMC. Dilakukan simulasi dengan memvariasikan posisi kelompok batang kendali untuk memperoleh nilai reaktivitas batang kendali. Data reaktivitas batang kendali digunakan untuk memperoleh nilai reaktivitas lebih, shutdown margin, dan kurva reaktivitas integral dan diferensial dari batang kendali. Dalam simulasi dilakukan pula perhitungan tally terhadap fluks neutron dan heating untuk memperoleh distribusi fluks dan nilai PPF. Perhitungan tally dilakukan dengan metode FET (functional expansion tally). Pada keadaan BOL (beginning of life), reaktor memiliki reaktivitas lebih sebesar 10,97 % Delta k/k, yang berkurang menjadi 0,50 % Delta k/k setelah penambahan Gd, PPF radial sebesar 1,6541, PPF aksial sebesar 1,2549, dan Shutdown Margin sebesar -6,61 % Delta k/k. Nilai total reaktivitas integral dari BK1 sebesar -6,11 % Delta k/k, dari BK2 sebesar -7,12 % Delta k/k, dan dari Kompensator sebesar -1,00 % Delta k/k. Reaktor beroperasi pada spektrum termal dengan puncak fluks berada di titik tengah volume aktif

Nuclear energy is a promising source of energy that has the potential to reduce carbon emissions. The development of nuclear reactors has shifted towards smaller, safer and more economical designs such as Small Modular Reactors and Microreactors. In this study, we perform an analysis of some of the main safety parameters in the design of a hydride microreactor in accordance with the International Atomic Energy Agency (IAEA) standards. These parameters include the shutdown margin, power peaking factor (PPF), and control rod reactivity. The reactor was modeled using the openMC simulation code. A simulation was conducted by varying the position of the control rod groups to obtain the value of the control rod reactivity. The reactivity data was then used to obtain the excess reactivity, shutdown margin, and integral and differential reactivity curves of the control rod. The simulation also performed tally calculations on neutron flux and heating to obtain the flux distribution and PPF value. The tallies is calculated using FET (Functional Expansion Tally) method. At the beginning of life (BOL), the reactor had an excess reactivity of 10.97% Delta k/k, which decreases to 0.50% Delta k/k after the addition of Gd, a radial PPF of 1.6541, an axial PPF of 1.2549, and a shutdown margin of -6.61% Delta k/k. The total integral reactivity value of the CR1 was -6.11 % Delta k/k, CR2 was -7.12 % Delta k/k, and the compensator was -1.00 % Delta k/k. The reactor operates in the thermal spectrum with a peak flux located at the center of the active volume.

Kata Kunci : reaktor mikro, reaktivitas, batang kendali, fluks neutron