Neutron Shielding Calculation of a Beam Stopper for the Thermal-TAS at HANARO using MCNP6

It can be classified as a virtual source, neutron optics components, Monochromator Shielding Unit (MSU), Sample table and Analyzer and Detector bank. At a monochromator, specific wavelength of neutron beam is selected by the Bragg scattering theory. Because the neutron beam comes from reactor source has high intensity, massive shielding units are placed around monochromator. After monochromator, selected neutron beam goes toward sample table. This is a brief account of the Thermal-TAS experiment. To achieve high quality experimental results, signal noise should be controlled. Signal noise can come from not only electronic hardware system but also un-necessary neutron background. To reduce background, proper shielding components should be placed around optical components. Monochromator, analyzer and detector have their own shielding components but sample table doesn't in current status of Thermal-TAS. To reduce background occurred on sample table, direct neutron beam that comes from monochromator should be blocked. In this paper, basic design and radiation shielding calculation of direct beam stopper shielding component have been conducted. A conceptual design and shielding calculation of a neutron beam stopper for the thermal-TAS at HANARO has been conducted. With this result, a beam stopper segment will be fabricated. After further procedures such as mechanical, electronic design and fabrication of a driving part of the stopper, a neutron beam stopper system will be installed on the thermal-TAS at HANARO