Dear sirs,
Please let me introduce you that we are writing from Saipem 12000, a 6th generation Ultra Deepwater Drillship operating in Angola.
I would ask you some questions related to a radioactive source that we have onboard. In an operating room there have been installed two nuclear density gauges with a Cs137 source fixed approximately at 2 meters height from floor level (photos enclosed to better clarify). The exposed part of the isotope is placed towards the wall that separates two different rooms. On the other side there is a walkway, indeed little used.
The clearance between receptor and wall of adjacent room is 10 cm. Radiation passes through the wall: it has been measured, by means of a detector, a radiation level that reach its maximum level of 22 µSv/h exactly in correspondence of the source. In the other room, 1.60 meter from floor level (virtually in correspondence of the same source), the detector, attached to the wall, measured 1 µSv/h, but it was 0 µSv/h after few centimeters.
What I would like to know is: do we need to put some protection on the wall or anyway round the source to reduce the intensity of radiations spread? Which kind of solution could you, in case, suggest us? Which shielding level would you allow us to obtain?
Waiting for your kind reply, I thank you in advance for your attention.
Best regards.
RP Cirkus 
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