Secret memo reveals how vulnerable nuclear subs are to Fukushima-style meltdown

With the world watching the Japanese nuclear catastrophe spiral out of control, the UK Ministry of Defense (MOD) inadvertently released secret information about the vulnerabilities of British and US nuclear submarines according to news reports.  The Daily Star reports:

A classified government report into the subs’ ­vulnerabilities has been published online with key parts blacked out to prevent ­sensitive material getting into the wrong hands.

But a massive blunder has meant anyone with basic computer knowledge could reverse the censorship – and read every word of the ­previously “restricted” report.

It reveals how easy it would be to cause a Fukushima-style reactor meltdown in a sub and details the ­capabilities of US vessels.

The report was published on Parliament’s website after a Freedom Of Information request by anti-nuclear ­campaigners.

The MOD document states:

Loss of (reactor) Coolant Accident (LOCA). All pressurised water reactors are potentially vulnerable to a structural failure in the primary circuit, causing a rapid depressurisation and boiling off of most of the cooling water. This results in failure of the fuel cladding, and a release of highly radioactive fission products outside the reactor core. While the further containment provided by the submarine’s pressure hull may contain the majority of this material inside the submarine, some leakage is likely to occur and in any event the radioactive “shine” from the submarine poses a significant risk to life to those in close proximity, and a public safety hazard out to 1.5km from the submarine. Current designs of UK and global civil power plants have systems for safety injection of coolant into the reactor pressure vessel head and passive core cooling systems. US nuclear submarines have similar systems suitably engineered for the submarine environment. UK submarines compare poorly with these benchmarks, with the ability to tolerate only a structural failure equivalent to a 15mm diameter hole, and an assessed higher likelihood of this occurring due to the materials used, the complexity of systems and the number of welds. It is assessed that in the current UK PWR2 plant the initiating structural failure causing a LOCA is twice as likely to occur as in equivalent civil and submarine reactor good practice.


Although the memo rates US subs as safer than UK subs, the possibility of a Fukushima-style meltdown could still contaminate a wide area.  In 1960, Hawai’i had a close call with a nuclear submarine accident when an explosion and fire rocked the USS Sargo while in port:

USS SARGO suffers an explosion and fire in her aft end while docked at Pearl Harbor. The fire starts from a leak in a high-pressure line that was pumping oxygen aboard. The explosion occurs a few moments later. When dock units and boats are unable to bring the fire under control quickly, officers take the SARGO a short distance from the dock and submerge it with the stern hatch open to put out the blaze. The Navy says the ship’s nuclear reactors were sealed off. and there was “absolutely no danger of an explosion from the reactor compartment.” The submarine is extensively damaged and is drydocked taking three months to repair. The SARGO is the first nuclear ship in the Pacific Fleet and was scheduled to take the visiting King and Queen of Thailand on a cruise the next day.

Hawai’i is the homeport for most of the submarines in the Pacific Fleet:

Commander, Submarine Squadron 1 (COMSUBRON One)
USS Bremerton (SSN 698)
USS La Jolla (SSN 701)
USS Charlotte (SSN 766)
USS Greeneville (SSN 772)
USS Texas (SSN 775)
USS Hawaii (SSN 776)

Commander, Submarine Squadron 3 (COMSUBRON Three)
USS Jacksonville (SSN 699)
USS Olympia (SSN 717)
USS Chicago (SSN 721)
USS Key West (SSN 722)
USS Louisville (SSN 724)
USS North Carolina (SSN 777)

Commander, Submarine Squadron 7 (COMSUBRON Seven)

USS Pasadena (SSN 752)
USS Columbus (SSN 762)
USS Santa Fe (SSN 763)
USS Tucson (SSN 770)
USS Columbia (SSN 771)
USS Cheyenne (SSN 773)

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