The following is part of a Chinese Global Times article of February 6, 2018 by "Beijing-based naval expert" Li Jie at http://www.globaltimes.cn/content/1088479.shtml :
“...[India's first indigenous nuclear submarine] INS Arihant passed all trials in February 2016 and was commissioned into service in August , making India the sixth country in the world to put a nuclear-armed submarine into operation. That was considered a milestone in the history of Indian Navy's development.
However, it was recently disclosed that the vessel had suffered a mishap after less than two years and not sailed for more than 10 months.
According to the Hindu, INS Arihant's propulsion compartment was damaged after water rushed in when a hatch on the rear side was left open by mistake. Since the accident, the submarine has been undergoing repairs and clean-up. Besides other repair work, many pipes had to be cut open and replaced. "Cleaning-up" of a nuclear submarine is a laborious task that requires a lot of effort, money and time.
The Indian submarine was built at a cost of $2.9 billion. Why did such a silly human error occur so as to damage it? The direct causes seem to be inadequate management, indiscipline and slackness among officers and soldiers of the Indian Navy.
...India has long dreamed of becoming a military power. It hopes to acquire more core defense technologies as soon as possible. However, most of India's weapons are purchased from major military powers including Russia, France, the UK and the US. The sources of India's weaponry and equipment are complicated.
Norms and technical standards that various countries follow to make weapons are different. Coupled with the fact that India is also developing indigenous weapons, it's fair to say that the country's arsenal is a hodgepodge.
SEE WHILE GLOBAL TIMES ARTICLE.
(Illustration by Liu Rui/GT in Chinese Global Times article, February 6, 2018 at http://www.globaltimes.cn/content/1088479.shtml)
All submarine services have accidents, some tragically fatal. China would do well to remember the fate of Chinese Navy’s (PLA-N's) Type 035 Ming submarine No. 361:
In 2003, “all 70 crew members [of 361] died when the submarine's diesel engine used up all the oxygen (because it failed to shut down properly) while the boat was submerged on April 16, 2003. The submarine, which was [extraordinarily] commanded by [a] Commodore Cheng Fuming (程福明), had been taking part in naval exercises east of Inner Changshan Islands in the Bohai Sea of Northeastern China. Along with its normal complement, the crew also included 13 trainee cadets from the Chinese naval academy.
See a less critical Submarine Matters article of January 15, 2018 on INS Arihant's accident.