US Navy Nuclear Propulsion Plant Operator explains when a submarine reactor can be run at higher than 100% (and why the 105% on the reactor ordered in The Hunt for Red October movie would not be worth any risk to the ship and crew)

US Navy Nuclear Propulsion Plant Operator explains when a submarine reactor can be run at higher than 100% (and why the 105% on the reactor ordered in The Hunt for Red October movie would not be worth any risk to the ship and crew)

By Dario Leone
Mar 3 2023
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Parameters for authorizing operating a US Navy submarine reactor plant above practicable design limits is well defined by NAVSEA 08 (which is the Naval branch of the Department of Energy).

The Hunt for Red October is a compelling and exciting Cold War thriller.

The movie premiered on Mar. 2, 1990 and starred Alec Baldwin, former Royal Navy sailor Sean Connery, and US Marine Scott Glenn. The film was based on the novel by Tom Clancy published by the Naval Institute Press. The Naval Institute had never published original fiction but decided to take a chance on the unknown Clancy who was working as an insurance agent at the time. The novel became a national bestseller and the film earned a worldwide gross of over $200 million.

Every submarine geek has seen the movie and every submarine geek recalls when after Red October fails to appear for the exercise Captain Viktor Tupolev (the Commander of The Konovalov, a Soviet Alfa class submarine) orders:

“Go to 105% on the reactor.”

Can a nuclear submarine reactor be run at higher than 100% like Tupolev does with the Konovalov to chase the Red October?

‘The answer is yes,’ E Franc, former US Navy Nuclear Propulsion Plant Operator (1988–1995), says on Quora.

‘Here’s the thing… on American subs, the captain has done every other officer’s job on the boat to get to that job; sub captains are extremely knowledgeable and competent technicians. (They usually lack people skills, however. The burden of the job simply destroys their personalities. I worked for submarine and surface commanders and by far sub commanders were the most difficult; so much so that if I were to encounter a former sub commander out and about on the town, I would excuse myself ASAP. We would not get along. I’ve been out 25 years and it hasn’t happened yet!) So, the captain is WELL aware of the precise design criteria of the plant and would not have to consult with the engineer concerning a decision like that. Also, sub captains have Eyes Only documents to which they, and only they, are privileged. One of these docs is the actual capacity of the power plant and how to utilize that capacity if needed. Design operating safety margins (not test margins or max pressure and temperature margins) are usually 110–115% of actual practicable operating parameters simply to avoid stressing equipment. THESE SPECS ARE KNOWN BY THE CREW: THESE ARE NOT WHAT THE CAPTAIN IS PRIVY TO.’

US Navy Nuclear Propulsion Plant Operator explains when a submarine reactor can be run at higher than 100% (and why the 105% on the reactor ordered in The Hunt for Red October movie would not be worth any risk to the ship and crew)
Captain Viktor Tupolev, the Commander of The Konovalov, a Soviet Alfa class submarine featured in The Hunt for Red October movie

He continues;

‘Now, if a captain of any nuclear-powered vessel of the American Navy were to order operation of a power plant to these classified parameters it had better be for a DAMN good reason or said captain will most certainly be relieved of command post haste. We are talking extreme time of war kind of stuff. The good news for the boat skippers is that the parameters for authorizing operating a reactor plant above practicable design limits is well defined by NAVSEA 08 (which is the Naval branch of the Department of Energy).

‘All that being said, going to, “One hundred and five on the reactor” would not have achieved enough extra speed to be worth any risk to the ship and crew. The skipper would have ordered a specific turn speed of the main shaft with a “do not exceed 105%” order. For example, “All ahead flank so many turns, do not exceed xxx%.” This is because water temperature and depth will make a big difference concerning how many turns you get for such and such level of power. Colder water is denser and makes for more resistance on the screw and therefore more power to achieve a given number of turns on the screw. However, due to the higher density of the water, slightly more distance is achieved per turn. There are charts to accommodate this. Also, at such high underwater speed, the sub would have made so much noise that EVERYBODY in the Atlantic would know exactly where that sub was and where to go to avoid it, especially Red October, and the Alpha could not have heard anything due to the flow noise, especially Red October.’

Franc concludes;

‘That stuff was not in the book (Tom Clancy knew better) but it made for great drama. Still one of my favorite movies.’

Photo credit: Paramaount Pictures and U.S. Navy

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Dario Leone

Dario Leone

Dario Leone is an aviation, defense and military writer. He is the Founder and Editor of “The Aviation Geek Club” one of the world’s most read military aviation blogs. His writing has appeared in The National Interest and other news media. He has reported from Europe and flown Super Puma and Cougar helicopters with the Swiss Air Force.
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