Radiological shielding design for the TOF polarisation analysis spectrometer Pelican at the OPAL reactor

The shielding for the time-of-flight Polarisation Analysis Spectrometer (Pelican) located at the OPAL reactor (ANSTO) was designed using the Monte Carlo code MCNP 4B. The proposed shielding design has produced compact shielding assemblies, such as the Pelican monochromator drum, lead snout interfaced to guide shielding, and shielding around the Optical System, Sample Chamber and Detector Chamber Systems. These arrangements are consistent with safety requirements, floor load limits, and cost constraints. The neutron dose rates around the Pelican instrument were reduced to < 0.5 μSv/h and the gamma dose rates were lowered to a safe working level of ≤ 3 μSv/h. The Optical System, with its components and the Detector Chamber were housed in borated polyethylene to shield from background signal noise.