A Procedure for the Recovery of RN Submarine Failed Polymer Electrode Membrane (PEM) Cell Stacks 2003-01-2648
O2 provision on Royal Naval Submarines is accomplished via the Wellman Defence Low Pressure Electrolyser (LPE). The LPE utilises a Polymer Electrode Membrane (PEM) electrolysis cell stack, which produces O2 at near ambient pressure (0.7 bar) and the by-product of H2 at 7-bar pressure.
The LPE has seen continuous service within the RN fleet of nuclear powered submarines since the early 1980's and particular cell stacks have accumulated in excess of 30,000 hours operational service.
The cell stack had enjoyed a 100% reliability record until the year 2001 when two separate incidents of cell stack failure occurred within the fleet. The root cause of cell stack failures was identified to a breakdown of the LPE Polypropylene filter element allowing resin beads from the demineraliser column to enter the cell stack via the process water inlet pipe. Subsequently, the resin beads blocked individual cells causing a reduction in flow of demineralised water across the cell membranes leading to overheating and ultimately, cell failure.
This paper follows on from the paper, “Investigation and Analysis of Polymer Electrode Membrane (PEM) Cell Stack Failures in Royal Navy (RN) Submarines”  that was presented at ICES 2002.
This paper describes:
The procedure developed by Wellman Defence Limited in conjunction with the Ministry of Defence for the recovery of one LPE cell stack from the two failed units.
The testing and validation process for the recovered unit.