Hi Cees,
As far as I am aware this is a long term ongoing project being conducted by volunteer members of The Society of Friends of Hendon (great bunch of guys) in order to prevent any further corrosion. The rear turret is removed during work to give the guys working in the fuselage more light and ventilation while carrying out the procedure.
You can see additional pictures of the work being carried out by following the link below (then scroll to the 'continuing care' section near end of page)
In addition, the following text from the same page helps to explain the work further:
"After a full inspection a report was written for the museum detailing the condition of the Halifax and what The Society of Friends team could do by way of preservation/restoration. The museum concluded that the external surfaces of the Halifax were, as far as possible, to remain as they were other than any work required to stabilize it. The interior of the Halifax could undergo some conservation work. Currently work is ongoing in the interior to halt any further corrosion. This is a long and laborious process due to space limitations, keeping stress on the structure to a minimum and working within health and safety parameters. Work is also being carried out on two of the wing mounted bomb racks."
Hope that helps.
Regards
Linzee
