1. The boat departed on sea trials in the Sea of Japan from Bol'shoy Kamen'.
2. The fire fighting system activates in the 1st and 2nd compartments at a depth of 80 meters. There are forty one people in the two compartments. The anti-submarine ship Admiral Tributs and the salvage tug Sayany along with a helicopter depart Vladvostok to render assistance.
3. The boat surfaces. The four worst injured people are taken by helo to a hospital in Vladivostok. The rest of the injured and the bodies of the dead are transferred to ships. The Nerpa proceeds under her own power to port.
4. The boat arrives in port and the injured are flown by helos to hospitals in Fokino.
Il'ya Kramnik, RIA Novosti military commentator.
The incident on the Nerpa which has taken the lives of 20 people has become the biggest event on Russian submarines since the loss of the Kursk in 2000. As with any other event on nuclear submarines, this incident has drawn the attention of the Russian and the world press as well as giving birth to a multitude of rumors and versions.
For now it is difficult to paint an accurate picture since there hasn't been an official investigation yet, but one can get to the approximate root of the incident. To begin with, we have to define our terms and emphasize that the boat was still formally going through sea trials and wasn't accepted into naval service.
There was a catastrophe on K-152 Nerpa. That means an incident leading to the death of people when many people us the word accident which means an incident not leading to deaths. Officially the cause of the incident is the unsanctioned activation of the fire suppression system.
Further we have to deal with equipment that submariners use to fight on board fires. Russian submarines are equipped with two fire suppression systems. The first is a foam system, designed to fight local fires. The second is a chemical compartment flooding system, designed to extinguish large volume fires (except solid rocket fuel and ammunition fires) by means of filling the compartment with freon or its derivatives. Freon bonds with sticks to oxygen in order to put out the fire.
Freon is the most effective way to extinguish a fire, while it is also toxic and breathing it can lead to poisoning and death. This risk is justifiable in the harsh conditions on submarines and some have commented on the availability of individual breathing apparatus.
The compartment flooding system is located in all compartments on the boat except the reactor compartment (there isn't a permanent watch in the reactor compartment and it is protected by stations in the neighboring compartments) and it has two modes: "right there" and "from the neighboring compartment".
The system can be operated directly from the compartment, although on board third generation submarines, experts assert that it can also be activated from the control panel in central control (the "Molybden" system). In any case, activation of the system requires human intervention - all submariners stress that "self activation" is impossible. There is one incident recorded regarding an accidental discharge and it wasn't in the same compartment (the incident on K-77 on 13 Feb 1976) because of a mistake made during the assembly of the system during overhaul (markings on a valve were confused in the factory). But, in any case, the activation of the system can only occur with human intervention.
This system is installed on all boats in the Russian Navy and since there is no evidence that some other kind of, or new, system has been mounted on the K-152, it stands to reason that K-152 carries the standard equipment.
The order to use the system can not only be given from the central command post, but also by the commander of of the compartment on the scene. In accordance with damage control regulations the commander of the compartment has the following rights to use the system:
- when there is no comms with the central command post,
- when it isn't possible to find a fire or when the fire can't be extinguished immediately by other means,
- during a flash fire,
- where there is a fire in the regeneration substances (Russian Navy Blog comment: presumably meaning where there is a fire in substances that produce their own oxygen, like oxygen candles),
- during fires in uninhabited hermetically sealed spaces.
If crew members are caught in a fire and the resulting discharge of the fire suppression system, they have personal breathing devices, the IDA-59 or IDA-59M which allows 10 to 30 minutes of oxygen in a poisonous atmosphere (the amount of time depends on the intensity of breathing - when strenuous work is being done, the oxygen reserve depletes quicker).
The central command post can decide to activate the system in a compartment and issue a corresponding order automatically through the fire alarm system or on the ship wide announcing system. It should be noted that the computerized fire alarm system gives false alarms once in a while, so comms between the affected compartment and the central command post are important. But it is only a fire alarm and generally not a command to activate the fire suppression system.
Having been briefed on the fire suppression system, we can again turn our attention to what happened on K-152. It is known that the boat, which has just been recently constructed, was undergoing trials. There was more than just the Navy crew of 81 on board in connection with the trials. There were a lot of civilian specialists - workers and engineers, a total of 208 on board. It has to be noted that the majority of these people don't have damage control experience or know what to do during a casualty on board a submarine - they just don't learn that, or at a maximum, they have a short theoretical course.
The civilian specialists were part of the sea trials, preparing the boat for transfer to the Navy together with the crew, checking the systems.
So what happened in the bow (torpedo) compartment on K-152? Sifting through the official version produces evidence that none of the injured (21 total) didn't have burns. One can deduce the following: there wasn't a fire on the boat. It's possible that there was a small local fire, leading to smoke in the compartment and a false alarm in the fire alarm system. As a result, either by command from the central command post where they didn't investigate the situation thoroughly, or on the scene - they decided to activate the fire suppression system in the first and second compartments simultaneously.
As a consequence of the discharge, the atmosphere in the first and second compartments became unbreathable, leading to deaths. It must be noted that 36 out of the 41 casualties were civilians which means that they either didn't know how to use their emergency breathing devices or, possible but less likely, there wasn't enough of them to go around in the crowded conditions on the submarine.
Since the truth isn't known yet, the guilty haven't been found yet. But conclusions can already be drawn from the incident. At a minimum, workers and engineers participating in construction and sea trials have to be trained to the same standard of the crew in what to do in the event of a casualty on a submarine, including during a fire and activation of the fire suppression system. Beside that someone has to ask if its necessary to take to sea triple the normal compliment during trials and testing - a crowd like that produces nothing except disorder.
Now it remains to be hoped that some lessons will be learned from this tragedy and that nothing like this happens again. Not on the Nerpa or any other submarine.
U-96 commenter Timofey Sklyankin adds the following:
Like I promised, here is some more detailed information which was received directly from participants in the event and also from representatives of NPO Avrora, the manufacturer of the fire suppression system on board this class of nuclear submarine.
1. Project 971I (I for Import) SSN K-152, factory number 518. The boat was designed for leasing to the Indian Navy through RosOboronEksport and the cost of the contract was about $670M. The boat was conducting sea trials at periscope depth with the factory crew on board, the regular crew and a large number of contractors on board. There were representatives from NPO Avrora on board.
2. Around 2030 there was an unsanctioned activation of the fire suppression system and as a result freon was released into the second compartment (where the central command post is located) and the alarm system activated. According to eyewitnesses who were using their IDAs (a second, the rep from Avrora, managed to get out of the compartment), the alarm was very quiet compared to the usual "roar", which evidently played its own unpleasant role for those sleeping.
3. Before we move on to possible causes, it is worth going over the fire suppression system installed on the Nerpa in detail. The system is controlled by the Molibden-BS, manufactured by NPO Avrora and has the following structure:
In each compartment (designated in Roman numerals) there is a 200 liter freon gas tank (C) and each tank has three exits controlled by electromagnetic valves. One exit leads to the compartment where the tank is located and the other two lead to the neighboring compartments. In this way the second compartment can by supplied with freon from the tanks in the three compartments, which is what happened in this case (according to eyewitnesses, the concentration of freon was so high that droplets formed on the walls and equipment!).
The tanks can be controlled three ways (I will emphasize that none of these methods are automatic):
First, there is the Molibden system (A) in the central command post, located in the second compartment, where the operator or watch stander can decide which tanks to fire into which compartments. This choice is made with a combination of barrel switches. Second, in each compartment there is a Molibden control panel for that compartment (B) which controls the flow of freon from the three tanks into a given compartment. The compartment commander or the watch decides to enter the info on a keyboard, verifies it on a liquid crystal display and then uses the control lever. Third, like I already said, every exit from the tank has a valve which can be opened manually like the "turn of a faucet".
4. Now the most interesting part:
The freon was delivered to the second compartment from all three tanks. Since one can pretty much exclude the possibility of that all three taps were turned by three different people simultaneously in three different compartments and the control panel (A) in the command post is under the control of an operator, one of two things most likely happened.
First version: The choice to empty three tanks of freon into a compartment of sleeping people was entered into the system from the keyboard on control panel (B) located in the second compartment. Since an excessive amount of freon was released, this raises the question of sabotage. This issue will probably be resolved since there is a sub-system of Molibden called Rotor (D), which functions like the black box of an airplane and records all the parameters of the system. This equipment block, as it was explained to me, has already been removed by the FSB and is the object of investigation.
Second version: There was a technical fault in the Molibden system which led to a mistaken activation of the system in the second compartment. The NPO Avrora representatives exclude this possibility. Honestly, I also doubt such a "happy" mistake since the firing of all three tanks into one compartment seems doubtful for now.
In general, we await the expertise of the Rotor system. Taking into account how many procurators are there now (a personal representative of the President himself has taken charge), it wont be soon. I'll keep you updated if I find out anything.