Poor maintenance/lax safety standards & Peroxide is a bad combo.
Very likely if handled incorrectly but fortunately we don't see too many exploding subs these days!
The truth is probably a combo of much of the above. The 90's was a really bad period in Russia's history and a lot of neglect - esp in the navy - took place. But as Alamo said the Kursk was brand new and really a showpiece for the Russian Navy. It also proudly displayed the double headed eagle as a symbol of national pride.
A lot of things happened on that day and many questions are still unanswered. Just looking at the initial rescue effort leaves a lot of questions. The sub was lying on the seabed 108m down which is quite shallow. The Kursk itself is 144 meters long. If they lifted the tail above water the rear escape hatch would have been exposed. There was claims that the rescue hatches were badly damaged and could not be opened, yet it took the Norwegian diving team only 25 minutes to open one of the "damaged" hatches. Hindsight is always easy but a lot of things don't quite add up.
Naval command was convinced that the two American subs were involved in the tragedy. They also knew about the presence of the British sub Splendid. The task force was stacked in such a manner in order to detect spy subs in the area. The investigators on the other hand dismissed the admirals version and excepted the possibility of the exploding peroxide torpedo as the likely cause, long before the Kursk was raised.
Well, the hatch on the stern we can call "damaged", as it was inexisting
The one on the bow was cracked. At least the sealing collar was because I saw it.
I would not exploit the "25min" factor either.
It is not true.
First, the hatch was opened on the second expedition, under the Rubin-Stolt Offshore contract, that took place Aug 17th-22nd from a deck of Seaway Eagle.
The inspection of stern rescue hatch and air valve started on 20th in the morning only. They have tried to open the covering hatch for a whole day, with help of a hydraulic manipulator of the ROV used for inspection, support, and water samples collection (they monitored the radioactivity level for a whole operation). Without much success, and the covering hatch was opened manually at night only, with the help of 500l balloon as I have said previously. They have opened the hatch, only to find out that the rescue shaft was already flooded. The team held a meeting on Aug 21st in the morning, how to proceed, and decided to increase radiation safety measures. They needed a special tool to open the lower hatch, and that was constructed by 10:30 Aug 21st. They finally opened the lower hatch about midday, reporting a big bulge of air coming out of the already flooded 9th compartment.
No idea where the "25min" story came from, but is not true.
Naval command was claiming lot's of things, in need to cover up th emess, but the most informative would be the officially considered scenarios. There were three of them, inspected simultaneously. A collision with underwater object, hitting a WWII mine, or on board weaponry cooking off. All three however consider the hull breach as initial cause trigging the sequence on.
Some misunderstandings emerge, because people are mixing the events.
We must keep in mind, that we talk about several different operations there.
The first one, was a Russian Navy serch&rescue operation, executed Aug12th-Aug17th with the assets of Northern Fleet, involving 22 ships&vessles and 3000 sailors under a direct command of admiral Popow.
The second one, involved Nowvegiand and Brits, with Seaway Eagle, Aug 17th-22nd. This operation, started as a rescue one, was transferred to non-rescue one on the evening of 19th August, in a curse of meeting of the staff with commanding officer, admiral Wericz. That led to the withdrawing of the British personnel and LR5 SAR submersible.
The third one, was performed Oct 2000 from the deck of Regalia platform, belonging to Halliburton Norge. The main task of this mission, was to recover bodies, find documents, and make a close inspection.
The last but not least, a fourth mission, however it can be divided into two phases as well, was lifting of Kursk, after cutting off the whole remains of the 1st compartment. It was a year later, Sep 2001, with help of the Mammoth platform.