Thilagam, L and Subbaiah, K . V (2015) NEUTRON ABSORBERS AS LINER MATERIAL CHOICE ON NEUTRON STREAMING THROUGH DUCTS. In: Proceedings, NSRP-20, 28-30,October, Mangalore.

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Effectiveness of various neutron absorbing materials as linerson the inner surface of the ducts in order to reduce neutron streaming through duct has been studied. Percentage reductions in neutron ambient dose equivalent rates at the duct exit and along the axis of z-shaped duct configuration have been calculated employing boron mixed materials as beam liners. A continuous energy Monte Carlo (MC) code, MCNP has been used to perform neutron ambient dose equivalent rate calculations considering Am-Be neutron source at the duct entrance. Commonly used boron based neutron shield materials like Ferro boron with 11.8% and 15% boron by weight, boron carbide (B4C), borated paraffin with 3% boron, different borated polyethylene materials (B2O3+CH2 and B4C+CH2) with 5% and 10% boron are considered as lining materials. Results of present MC calculations show that lining beam ducts with the materials rich in hydrogen and boron i.e. borated polyethylene and borated paraffin produced from B4C mixing with CH2polymershave much impact on scattered neutron flux and hence on the neutron ambient dose equivalent rates due to streaming.The percentage dose equivalent rate reduction obtained as a function of liner thickness shows that the ambient neutron dose equivalent rate reductions are up to 60% for these materials at the duct exit for 5mm thickness. Due to higher hydrogen content, borated paraffin employing lesser boron content of about 3% also shows equal impact on neutron streaming compared to borated polyethylene (B4C+CH2) with higher boron content 5% and 10%, where the effect of increasing boron concentration has minimal effect on dose equivalent rate reduction.

Item Type: Conference or Workshop Item (Paper)
Uncontrolled Keywords: Monte Carlo methods, Boron liners, Neutron streaming, ICRP-74
Subjects: Departments at MU > Manipal Centre for Natural Sciences
Depositing User: MCNS Editor
Date Deposited: 09 Nov 2015 16:38
Last Modified: 09 Nov 2015 16:38

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