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Survival in the DISSUB

Initial actions
Initial Actions are designed to prepare the submarine and survivors for escape, these actions will be conducted immediately after the incident. The senior survivor would, at this time alert the authorities by releasing the indicator buoy and firing an ECB 699 and a Transponder 409, he would assess the situation onboard and decide on the preferred and safest method of escape.

Methods of Escape

Surface abandonment
All escapees would put on an escape suit and deploy a single man liferaft.
Await Rescue
This will be the preferred method of escape, in this instance, the internal pressure will be below the escape limit, and the atmosphere will be monitored and controlled within the calculated limits, and the radiation levels will be within the stated limits.
Planned Tower Escape
This method is used when calculated limits are reached and rescue by submersible is not available.
Immediate Tower Escape
This method of escape is used when conditions are deteriating and limits will eventually be reached. This could be that due to, pressure rising, or if the air provided for escape purposes had to be used.
Rush Escape
This method of escape would only be used as an absolute last resort. Uncontrollable flooding could persuade the survivor to conduct this type of escape.

Atmosphere Monitoring and Control

The major factor that will determine your continued survival in a DISSUB after an accident will be your ability to control the deteriorating atmospheric conditions, that will be encountered in the compartments of a Submarine that is disabled on the seabed. To enable survival in the DISSUB, the atmosphere needs to be continuously monitored and controlled and a breathable standard must be maintained using the equipment supplied.

The potential hazards in the atmosphere of a DISSUB

Increased atmospheric pressure – From internal flooding or ruptured H.P Systems – Which will raise the concentration levels of the gases in the atmosphere.
Increased Carbon Dioxide concentration - CO2 will be purged from the body into the atmosphere every time someone exhales.
Reduced Oxygen concentration - Survivors will be consuming the oxygen in the atmosphere every time they inhale.
The presence of Carbon Monoxide, Chlorine gas and particulates from smoke may also be evident.
Radiation – From reactor systems or shielding break-down.
The enviromental temparature change, compartment temperature will change, this will be determined by how cold the surrounding sea water temperature is.
The effect of CO2 on the human body will increase when the CO2 content in the atmosphere is subjected to any increase in atmospheric pressure i.e. The CO2 effect is multiplied with every increase of 1 Bar of pressure. The survivors must continually monitor absolute pressure and be ready to make an escape at any time.

Equipment available to control and maintain the level of toxic gases in the atmosphere

Carbon Dioxide Absorption Units (CDAU - left), powered either by ships 24 volt supply - or salt water activated batteries. A large fan will draw air through the canisters that are filled with soda lime granuals, the granuals will absorb the Carbon Dioxide from the atmosphere.

Oxygen is generated by burning a Self Contained Oxygen Generating candle (SCOG - right). These are sodium chlorate candles which produce approx. 2600 ltrs (2.6 cubic mtrs) of oxygen per candle over a burn time of approx 70 min.

ExtendAir® LiOH CO2 Absorbent Curtains will be introduced into service in 2007, this will improve the CO2 absorption capability onboard. There is a continuous length of approximately 50 feet of backing materiel – with 10.5inch.panels of LiOH absorbent attached (with perforations in between each panel).
Deployment: Determine desired lengths of each curtain to be cut from the continuous length (to allow hanging clear of water, obstructions, off the deck and ideally out of high traffic areas). Cuts to be made between panels in perforated areas using tools provided in the box. Hanging sheets vertically back to back without touching, assists in generating convection air currents that improve the airflow over the sheet and the rate of CO2 removal.
After 48 hours of exposure, deployed sheets can be removed if space is needed for additional hangings.

Personal factors that could extend survival time within a DISSUB.

Minimising metabolic rate has a major influence on survival time.

Do any heavy work early whilst survivors are still fresh.

Minimise all unnecessary work.

Encourage survivors to rest, sleep if possible.

Conservation of body heat reduces the consumption of oxygen.

Put any extra clothing on, use the thermal liners, get into sleeping bags.

Get close to each other.

If possible open up the bulkhead doors to increase the breathable volume available,
this will help reduce the build up of Carbon Dioxide and any small pressure increases,
it will also give access to more equipment and stores.

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