Chinese Nuclear Submarine Crew Poisoned By Hydrogen Sulphide

[toucana]

Persistent rumours that the PLAN (Peoples Liberation Army Navy) of Communist China had a nuclear submarine disaster in late August of this year have reappeared recently with new details.

https://www.youtube.com/watch?v=3X2BjWnq9R8

According to this update, a CCP type 093 nuclear submarine #417 became trapped in one of the Chinese navy’s own anti-submarine underwater boom defense systems in the Yellow Sea, near the mainland Chinese coastal city of Shantou, to the southwest of Taiwan.

According to a Twitter/X post by @Luoxiangzy on 19th October, the incident occurred at 8.30 a.m. on Monday August 21. The submarine #417 had sailed from Qingdao naval base and was carrying out an underwater survey mission when it became trapped by a chain-boom intended to deter intrusions by US navy submarines.

The ship’s captain Colonel Xue Yongpeng despatched a diver with oxy-acetylene cutting gear to free the submarine, but when the diver returned and attempted to re-enter the vessel by knocking on the escape hatch, he received no response. The diver then violated regulations by surfacing, and was promptly rescued by two frigates that were on patrol nearby. The surface vessels asked for support from the Lianyungang Baitabu Air Base, but rescue operations were delayed by heavy thunderstorms in the area.

An airpump was subsequently flown out to the scene by helicopter, and divers successfully connected an airline to the submarine, but too late. When the vessel was subsequently brought to the surface and opened up, the 55 crewmen onboard were all dead. Forensic autopsy subsequently disclosed that they had died from hydrogen sulphide poisoning.

The hydrogen sulphide (H2S) probably came from a malfunction in the charging and venting system of the submarine’s heavy duty lead acid battery system which typically uses lead alloy plates in an electrolyte solution of 35% sulphuric acid and 65% water. (Some newer submarines use Lithium cells instead).

https://ehs.umass.edu/sites/default/files/Battery%20SOP.pdf

According to the Chinese accident report, the vessel was not fitted with a hydrogen sulphide monitor alarm. The gas is invisible, flammable and highly toxic, and while it can normally be detected at low concentrations by its revolting “rotten eggs” smell, it quickly induces anosmia or loss of smell in higher concentrations.

The Chinese CCP leader Xi Jinping who was attending a BRICS Summit in South Africa abruptly cancelled a keynote speech after being briefed on the disaster. His planned speech to the Business Forum on 22 August was given by Wang Wentao the Minister of Commerce instead.

Edited November 2, 2023 by toucana
fixed typo in 'Sulphide' (2nd last para)

[John Cuthber]

24 minutes ago, toucana said:

The hydrogen sulphide (H2S) probably came from a malfunction in the charging and venting system of the submarine’s heavy duty lead acid battery system which typically uses lead alloy plates in an electrolyte solution of 35% sulphuric acid and 65% water.

That does not make much sense.

[toucana]

5 minutes ago, John Cuthber said:

That does not make much sense.

From the second article cited in my OP:

"In addition, overcharging a lead acid battery can produce hydrogen sulfide gas. This gas is colorless, poisonous, flammable, and has an odor similar to rotten eggs or natural gas. The gas is heavier than air and will accumulate at the bottom of poorly ventilated spaces."

https://ehs.umass.edu/sites/default/files/Battery SOP.pdf

see also:

"Under normal operating conditions, the gasses evolved are hydrogen (H) and oxygen (O). However, under extreme conditions other gasses may be produced such as hydrogen sulphide (H2S). Some strange gasses are also given off in very small quantities such as carbon dioxide (CO2). This document only considers the evolution of hydrogen, oxygen and hydrogen sulphide."

https://www.blueboxbatteries.co.uk/blog/industrial-battery-gassing-37

I also came across one news report from USA where people were found dead in a car. It was initially thought they had suffered from carbon monoxide poisoning, but forensic tests showed they had  died from hydrogen sulphide poisoning from a lead acid car battery that had been shorted out by a defective starter motor.

 

And here is an exhaustive academic study commissioned by the US Navy in a 2002 review of SEAL (Submarine Escape Action Levels) for hydrogen sulphide contamination in submarines, which discusses trigger thresholds for emergency action to be taken in response to the detection of levels as low as 10 to 15 PPM of this gas:

https://nap.nationalacademies.org/read/10242/chapter/9

[exchemist]

3 hours ago, toucana said:

Persistent rumours that the PLAN (Peoples Liberation Army Navy) of Communist China had a nuclear submarine disaster in late August of this year have reappeared recently with new details.

https://www.youtube.com/watch?v=3X2BjWnq9R8

According to this update, a CCP type 093 nuclear submarine #417 became trapped in one of the Chinese navy’s own anti-submarine underwater boom defense systems in the Yellow Sea, near the mainland Chinese coastal city of Shantou, to the southwest of Taiwan.

According to a Twitter/X post by @Luoxiangzy on 19th October, the incident occurred at 8.30 a.m. on Monday August 21. The submarine #417 had sailed from Qingdao naval base and was carrying out an underwater survey mission when it became trapped by a chain-boom intended to deter intrusions by US navy submarines.

The ship’s captain Colonel Xue Yongpeng despatched a diver with oxy-acetylene cutting gear to free the submarine, but when the diver returned and attempted to re-enter the vessel by knocking on the escape hatch, he received no response. The diver then violated regulations by surfacing, and was promptly rescued by two frigates that were on patrol nearby. The surface vessels asked for support from the Lianyungang Baitabu Air Base, but rescue operations were delayed by heavy thunderstorms in the area.

An airpump was subsequently flown out to the scene by helicopter, and divers successfully connected an airline to the submarine, but too late. When the vessel was subsequently brought to the surface and opened up, the 55 crewmen onboard were all dead. Forensic autopsy subsequently disclosed that they had died from hydrogen sulphide poisoning.

The hydrogen sulphide (H2S) probably came from a malfunction in the charging and venting system of the submarine’s heavy duty lead acid battery system which typically uses lead alloy plates in an electrolyte solution of 35% sulphuric acid and 65% water. (Some newer submarines use Lithium cells instead).

https://ehs.umass.edu/sites/default/files/Battery%20SOP.pdf

According to the Chinese accident report, the vessel was not fitted with a hydrogen sulphide monitor alarm. The gas is invisible, flammable and highly toxic, and while it can normally be detected at low concentrations by its revolting “rotten eggs” smell, it quickly induces anosmia or loss of smell in higher concentrations.

The Chinese CCP leader Xi Jinping who was attending a BRICS Summit in South Africa abruptly cancelled a keynote speech after being briefed on the disaster. His planned speech to the Business Forum on 22 August was given by Wang Wentao the Minister of Commerce instead.

But why would a nuke have banks of lead acid batteries? Surely that would be in diesel electric subs. If it had been one of those, it would be discharging the batteries while submerged. To grossly overcharge them enough to generate H2S it would need to be on the surface with the engine running.

So I’m a bit suspicious of this story. Especially since it seems to come from YouTube. Is there any corroboration from a reliable source?

Edited November 2, 2023 by exchemist

[John Cuthber]

2 hours ago, toucana said:

From the second article cited in my OP:

"In addition, overcharging a lead acid battery can produce hydrogen sulfide gas. This gas is colorless, poisonous, flammable, and has an odor similar to rotten eggs or natural gas. The gas is heavier than air and will accumulate at the bottom of poorly ventilated spaces."

https://ehs.umass.edu/sites/default/files/Battery SOP.pdf

see also:

"Under normal operating conditions, the gasses evolved are hydrogen (H) and oxygen (O). However, under extreme conditions other gasses may be produced such as hydrogen sulphide (H2S). Some strange gasses are also given off in very small quantities such as carbon dioxide (CO2). This document only considers the evolution of hydrogen, oxygen and hydrogen sulphide."

https://www.blueboxbatteries.co.uk/blog/industrial-battery-gassing-37

I also came across one news report from USA where people were found dead in a car. It was initially thought they had suffered from carbon monoxide poisoning, but forensic tests showed they had  died from hydrogen sulphide poisoning from a lead acid car battery that had been shorted out by a defective starter motor.

 

And here is an exhaustive academic study commissioned by the US Navy in a 2002 review of SEAL (Submarine Escape Action Levels) for hydrogen sulphide contamination in submarines, which discusses trigger thresholds for emergency action to be taken in response to the detection of levels as low as 10 to 15 PPM of this gas:

https://nap.nationalacademies.org/read/10242/chapter/9

If your batteries are nearly on fire you will get some H₂S.
The academic book doesn't seem to mention batteries.

I'm reminded of the  story of the Kursk, where the official news said lots of things...

 

[studiot]

The action of charging lead-acid batteries leads to an increase in the strength of the sulphuric acid.

The reaction between hydrogen sulphide and sulphuric acid is well studied and leads to the release of sulphur dioxide (and elemental sulphur).

So why would a large enough quantity of hydrogen sulphide be released in this way ?

https://harvest.usask.ca/bitstream/handle/10388/etd-12202010-111342/PatriciaThesis.pdf?isAllowed=y&sequence=1

 

I agree with Cuthber and Exchemist and noting that the source is youTube which has become heavily contaminated with disinformation these days I am highly skeptical of the reports.

 

 

[StringJunky]

Could H2S have evolved from leaking human-waste tanks?

[TheVat]

I would guess such leaks tend to get fixed before they are that extreme, due to the intense odor.  At low concentration, H2S is very noticeable.  The whole story doesn't pass the...sniff test.

[sethoflagos]

25 minutes ago, StringJunky said:

Could H2S have evolved from leaking human-waste tanks?

Another possibility might be from opening a buoyancy tank that had been sealed for long enough for SRBs to poison its air contents. 

During my apprenticeship in the paper industry we had several fatal incidents due to personnel entry into poorly ventilated secondary water tanks without appropriate breathing apparatus. Concentrations as low as 0.1% v/v are often immediately lethal. It doesn't take much in a confined space.  

[toucana]

2 hours ago, exchemist said:

But why would a nuke have banks of lead acid batteries? Surely that would be in diesel electric subs. If it had been one of those, it would be discharging the batteries while submerged. To grossly overcharge them enough to generate H2S it would need to be on the surface with the engine running.

So I’m a bit suspicious of this story. Especially since it seems to come from YouTube. Is there any corroboration from a reliable source?

 Nuclear submarines do indeed have very large banks of lead acid batteries weighing over 2000lbs, with an energy storage capacity of up to 2.6MWh.  These batteries are often the main propulsive power system in such submarines - the PWR nuclear reactor is used via a heat exchanger to produce steam to run turbo-electrical generators that feed the main battery system which in turn feeds the main electrical propulsion motors. You can find a detailed account here :  http://large.stanford.edu/courses/2013/ph241/ditiangkin1/

Versions of this story first appeared in the UK Times newspaper on 4 October, although the earlier reports attributed the crew deaths to a failure of the oxygen system, rather than hydrogen sulphide exposure in particular.

https://www.ndtv.com/world-news/chinese-nuclear-submarine-suffers-catastrophic-failure-what-we-know-4451948#

https://www.thetimes.co.uk/article/china-kills-own-sailors-with-trap-set-for-us-and-british-vessels-75wdfkc2p  (pay-walled)

[swansont]

14 minutes ago, toucana said:

These batteries are often the main propulsive power system in such submarines - the PWR nuclear reactor is used via a heat exchanger to produce steam to run turbo-electrical generators that feed the main battery system which in turn feeds the main electrical propulsion motors

Batteries are a storage medium. The power comes from the reactor under normal operations.

Batteries will supply a limited amount of power in case the reactor is scrammed. 2.6 MWh is not a lot of energy when considering a reactor that produces a full power of ~100 MW.

[mistermack]

I'm pretty sure that the generators would directly drive the motor, not via the batteries. Batteries don't last long if you keep charging and discharging. They would be just for emergency power, I would say. Maybe the section got flooded, and seawater got into the batteries. 

During the world wars, submarine poisonings were common when leaks happened, often from depth charge damage. But without checking, I seem to remember that it was chlorine gas that they dreaded back in those days. Maybe from the salt in sea-water, or maybe the batteries used hydrochloric acid. 

It seems a big coincidence that the sub got tangled at the same time as a gas leak. Maybe the crew died, and the sub just kept on trucking till it hit something. 

[toucana]

7 minutes ago, swansont said:

Batteries are a storage medium. The power comes from the reactor.

Batteries will supply a limited amount of power in case the reactor is scrammed. 2.6 MWh is not a lot compared to a reactor that produces a full power of ~100 MW.

What the article I cited actually says is  - "Electricity generated from its nuclear rector is the main source of electrical and propulsion power for the submarine, but a battery, as a source of power, is required during emergency operations"

I suspect that what might have happened here is that the submarine used maximum emergency power to try and free itself when the vessel became trapped by an underwater boom, and that they may have overloaded their electrical systems and shorted out or damaged a battery badly creating an H2S hazard.

[exchemist]

55 minutes ago, toucana said:

 Nuclear submarines do indeed have very large banks of lead acid batteries weighing over 2000lbs, with an energy storage capacity of up to 2.6MWh.  These batteries are often the main propulsive power system in such submarines - the PWR nuclear reactor is used via a heat exchanger to produce steam to run turbo-electrical generators that feed the main battery system which in turn feeds the main electrical propulsion motors. You can find a detailed account here :  http://large.stanford.edu/courses/2013/ph241/ditiangkin1/

Versions of this story first appeared in the UK Times newspaper on 4 October, although the earlier reports attributed the crew deaths to a failure of the oxygen system, rather than hydrogen sulphide exposure in particular.

https://www.ndtv.com/world-news/chinese-nuclear-submarine-suffers-catastrophic-failure-what-we-know-4451948#

https://www.thetimes.co.uk/article/china-kills-own-sailors-with-trap-set-for-us-and-british-vessels-75wdfkc2p  (pay-walled)

This sounds very doubtful.  "If the incident has occurred, the global silence is perplexing. A nuclear submarine sinking should lead to global attention because a nuclear reactor leak due to damage can have serious consequences, including water contamination," a submarine expert told the EurAsian Times."

This report was on 4th October. There has been nothing since. If it were true, surely all manner of organisations would be up in arms about contamination risk etc. 

Failure of the oxygen system after a mere 6hrs seems most improbable. Nukes are designed to complete entire tours, lasting weeks, without the need to surface.  

[StringJunky]

10 minutes ago, exchemist said:

This sounds very doubtful.  "If the incident has occurred, the global silence is perplexing. A nuclear submarine sinking should lead to global attention because a nuclear reactor leak due to damage can have serious consequences, including water contamination," a submarine expert told the EurAsian Times."

This report was on 4th October. There has been nothing since. If it were true, surely all manner of organisations would be up in arms about contamination risk etc. 

Failure of the oxygen system after a mere 6hrs seems most improbable. Nukes are designed to complete entire tours, lasting weeks, without the need to surface.  

This is a Chinese vessel though, so we don't know if they are kitted out to the same principles as NATO's.

[toucana]

2 minutes ago, exchemist said:

This sounds very doubtful.  "If the incident has occurred, the global silence is perplexing. A nuclear submarine sinking should lead to global attention because a nuclear reactor leak due to damage can have serious consequences, including water contamination," a submarine expert told the EurAsian Times."

This report was on 4th October. There has been nothing since. If it were true, surely all manner of organisations would be up in arms about contamination risk etc. 

Failure of the oxygen system after a mere 6hrs seems most improbable. Nukes are designed to complete entire tours, lasting weeks, without the need to surface.  

From what I can gather, the submarine was subsequently freed and brought back to the surface again by rescue vessels. It was then taken back to the Qingdao naval base by PLAN salvage tenders - so there was never any issue with a loss of reactor containment, or release of radiation into the sea. This wasn't a deep water incident, it happened in relatively shallow coastal waters near Shantou city on the coast of Guangdong province.

It is indeed correct to say that the oxygen system of a nuclear submarine itself would not fail or run out in a matter of just 8 hours or so - which renders it even more likely that some other incident occurred -  such as a major battery fire or explosion that released toxic fumes and killed the crew.

One detail in the reports that caught my eye was that key items of rescue equipment (such as the large air pump used) had to be flown down from Lianyungang Baitabu air-base which is a long way to the north on the Jiangsu coast, nor far from the main Qingdao naval base. It seems that the Chinese navy simply did not have all the resources needed to handle this incident on hand, which led to some considerable delay.

Part of the radio-silence on this incident by China is probably motivated by extreme embarrassment at the ineptitude of the PLAN. Dissident sources say the Chinese leader Xi Jinping ordered a complete news blackout, and was said to have been furious when details of the accident began circulating  on Chinese language social media, and were subsequently leaked to the UK press by British intelligence.

[exchemist]

29 minutes ago, toucana said:

From what I can gather, the submarine was subsequently freed and brought back to the surface again by rescue vessels. It was then taken back to the Qingdao naval base by PLAN salvage tenders - so there was never any issue with a loss of reactor containment, or release of radiation into the sea. This wasn't a deep water incident, it happened in relatively shallow coastal waters near Shantou city on the coast of Guangdong province.

It is indeed correct to say that the oxygen system of a nuclear submarine itself would not fail or run out in a matter of just 8 hours or so - which renders it even more likely that some other incident occurred -  such as a major battery fire or explosion that released toxic fumes and killed the crew.

One detail in the reports that caught my eye was that key items of rescue equipment (such as the large air pump used) had to be flown down from Lianyungang Baitabu air-base which is a long way to the north on the Jiangsu coast, nor far from the main Qingdao naval base. It seems that the Chinese navy simply did not have all the resources needed to handle this incident on hand, which led to some considerable delay.

Part of the radio-silence on this incident by China is probably motivated by extreme embarrassment at the ineptitude of the PLAN. Dissident sources say the Chinese leader Xi Jinping ordered a complete news blackout, and was said to have been furious when details of the accident began circulating  on Chinese language social media, and were subsequently leaked to the UK press by British intelligence.

OK that makes sense. If they recovered the sub there might be no hooha.

[mistermack]

1 hour ago, toucana said:

I suspect that what might have happened here is that the submarine used maximum emergency power to try and free itself when the vessel became trapped by an underwater boom, and that they may have overloaded their electrical systems and shorted out or damaged a battery badly creating an H2S hazard.

That's an interesting thought, but I don't think so. If you wanted maximum power, you would probably use direct power from generators, rather than the much weaker battery power. 

Maybe getting caught up flipped the sub upside down, causing acid leak. 

[toucana]

3 minutes ago, mistermack said:

That's an interesting thought, but I don't think so. If you wanted maximum power, you would probably use direct power from generators, rather than the much weaker battery power. 

Maybe getting caught up flipped the sub upside down, causing acid leak. 

Accidents in subs often involve a 'cascade' of adverse events - as happened when the USS Thresher was lost during deep diving tests in April 1963. A high pressure leak in a salt water intake pipe shorted out a major electrical DB, which led to an unwanted reactor SCRAM. Ice crystals then formed in a key air valve system when they tried to blow the ballast tanks, leading to the total loss of the vessel and crew.

I suspect that some similar event cascade took place here. I agree that the crew probably tried to use direct generator power initially, the reactor may then have unexpectedly scrammed, forcing them to switch to emergency battery power - or there may have been some unintended feed-back charging loop that overloaded the batteries.

 

[mistermack]

Given the history of batteries on submarines, it's amazing that something like this could still happen. A modern design should surely recognise the risk, and put the batteries behind a bulkhead, with airtight doors in and out? And an electronic air quality detector, to be checked before entry?  On a boat of that sort of cost and sophistication, you would expect that sort of thing at the minimum.

[toucana]

9 minutes ago, mistermack said:

Given the history of batteries on submarines, it's amazing that something like this could still happen. A modern design should surely recognise the risk, and put the batteries behind a bulkhead, with airtight doors in and out? And an electronic air quality detector, to be checked before entry?  On a boat of that sort of cost and sophistication, you would expect that sort of thing at the minimum.

One of the problems faced by China and other Asian nations who wish to design and build submarine fleets of their own, is that critical elements of the key technologies required are embargoed by the USA and other NATO powers. So the Chinese have to do their own R&D, and find their own solutions to the construction challenges involved.

The video I cited in my OP went into this in more detail, and it included the technical drawing shown below. Now this is actually a prototype Taiwanese submarine, not a Chinese one, and it's a conventional diesel electric patrol boat, not a nuclear sub - but the key point is the colour of the keys in the graphics. All the items with red colour flags are highly embargoed items of technology (sonar and torpedo systems in particular ). Green flags are items that Taiwan can produce itself, and all the other flags are technologies that have to be sourced from abroad- It rather shows up the scale of the challenge facing them.

[swansont]

2 hours ago, toucana said:

What the article I cited actually says is  - "Electricity generated from its nuclear rector is the main source of electrical and propulsion power for the submarine, but a battery, as a source of power, is required during emergency operations"

I suspect that what might have happened here is that the submarine used maximum emergency power to try and free itself when the vessel became trapped by an underwater boom, and that they may have overloaded their electrical systems and shorted out or damaged a battery badly creating an H2S hazard.

I don’t know in detail how Chinese submarines work, but I doubt the battery runs the main propulsion system. That requires a lot of power, and is likely run directly from a steam turbine. The battery might run a motor used in emergencies, when main propulsion is unavailable, capable of a few knots.

If the primary propeller(s) became fouled, the emergency propulsion might be engaged, which likely has its own propeller.

44 minutes ago, mistermack said:

Given the history of batteries on submarines, it's amazing that something like this could still happen. A modern design should surely recognise the risk, and put the batteries behind a bulkhead, with airtight doors in and out? And an electronic air quality detector, to be checked before entry?  On a boat of that sort of cost and sophistication, you would expect that sort of thing at the minimum.

Different cultures place different emphasis on safety, and space is usually at a premium on a sub. And mistakes can be made. The US has safeguards and procedures put in place only after incidents revealed flaws, because sometimes they reveal flaws that don’t show up under normal ops, and are situations that you wouldn’t test for because it would be too dangerous to do so.

e.g. There were significant changes made after the Thresher was lost in the 60s.

https://www.usni.org/magazines/proceedings/2020/october/reflections-loss-thresher#:~:text=After the Thresher disaster%2C the,quick actuation in an emergency.

[toucana]

9 minutes ago, swansont said:

I don’t know in detail how Chinese submarines work, but I doubt the battery runs the main propulsion system. That requires a lot of power, and is likely run directly from a steam turbine. The battery might run a motor used in emergencies, when main propulsion is unavailable, capable of a few knots.

If the primary propeller(s) became fouled, the emergency propulsion might be engaged, which likely has its own propeller.

Chinese submarines use turbo-electric transmission systems to drive their propellors.

"The Russian, U.S. and British navies rely on direct steam turbine propulsion, while French and Chinese ships use the turbine to generate electricity for propulsion (turbo-electric transmission)"   https://en.wikipedia.org/wiki/Nuclear_marine_propulsion

One reason for using electric motors in the main propulsion system is to lower the acoustic noise profile of the vessel for silent running during operations.