ANNEX C. Special Design requirements  a) The Watertight Data Cable has to include:  b) Water-tight testing capability:  a. Two separate cables, one inside the torus terminated in a socket on the outside of the  torus, and a second cable (15m) that connects from the socket to the control box  (terminating in an RS485 connector.  b. The socket shall be waterproof (leak tight).  c. A protective EPDM sleeve shall cover the cable. It shall not be required that the  cable connectors be removed in order to install the sleeve.  A method for routine testing of the watertight seals (e.g. using a helium leak test) shall  be provided. The valve for introducing gas to the torus must be protected from  breakage during shipment and use.  The torus shall be marked externally to indicate the 0-degree position of detector head  1. The marking must be easily visible from the surface of a spent fuel pond and shall  consist of a line that is parallel to and above the front of the collimator of head 1.  The system shall be fully compatible with the IAEA PGET software, according to the  IAEA document  SG-UR-14008 -- Passive Gamma Emission Tomography (PGET)  Software -- v3 (2016-08-18) , which can be provided in advance to the awarded  contractor. Improvements to the design of the collimator, compared to the detailed specifications,  are welcome with the following constraints:  a. The collimator shall accommodate 91 detectors (7 back-end boards).  b. The collimator shall enable easier placement of detector components (back-end  board modules) inside;  c. Cable penetrations shall be redesigned to allow easier installation;  d. The horizontal pitch of the collimator openings (4.0mm +/- 0.01mm) and width  (1.5mm +/- 0.01mm) shall strictly remain the same.  e) Gamma-ray Collimator Redesign:  d) Data-Collection Software:  c) External Markings:  26 