Australian Submarine Reactors: Inspection & Maintenance

Australia's Prime Minister Morrison has sold the AUKUS submarine nuclear reactor concept as being a "sealed system" that therefore does not need complex Australian maintenance.

A January 14, 2022 comment from French Anonymous runs in the face of this, where Anonymous says:

"One the most critical element in a N plant is the steam generator (having pressurized water heated by the [Zirconium] Zr cladding on one side and steam for the turbine on the other side). Because it is a critical safety barrier it needs to be changed typically every 10 years in civilian plants. This is why in the US design it is located outside the reactor."

Anonymous has further advised: "Even diesel /non Nuclear submarines undergo typically 2 years long minimum complete overall maintenance at least every 10 years typically. Short maintenance periods of 4 to 8 months occurs in between."

Background

Artwork courtesy via Wikimedia Commons.
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This 2019 Stanford University website by Dylan Woodhead briefly describes how a submarine pressurised water reactor (PWR) works:

"The nuclear reactors on submarines [above] work just like every other nuclear reactor, but instead of producing electricity they work as a heat engine. The uranium fission releases energy that is used to heat up water. The water is heated in the reactor [see pink in artwork] and pressurized to prevent boiling but is then used to heat up a separate secondary system [gray] that produces steam. This steam then acts like any other steam engine and is used to drive turbines that power the propellers and the electric generator. The steam condenses to water and returns back [light blue] to the steam generator."

Pete Comment

1.  This means Australian nuclear engineers will need to regularly inspect the submarine  pressurised water reactor to prevent the escape of radiation and water/steam leaks. Starting from an Australian position of no nuclear submarine maintainers major maintenance may take far longer than 2 years for Australia's first nuclear submarines.

2.  Even so-called "sealed" submarine reactors need so much expert at-sea and in-port monitoring and maintenance that an essential qualification for US nuclear submarine commanders is years of experience as at-sea nuclear engineers. 

3.  Australia appears to be choosing the UK Royal Navy as the main AUKUS submarine builder and sponsor navy. But the UK reactor safety system appears to have a poorer record than the more thorough and expensive US reactor safety regulatory system. The UK's outgoing Trafalgar-class nuclear submarines have experienced the following leak problems:

"In 1998, [HMS] Trenchant experienced a steam leak, forcing the crew to shut down the nuclear reactor. In 2000 a leak in the PWR1 reactor primary cooling circuit was discovered on [HMS] Tireless, forcing her to proceed to Gibraltar on diesel power.^[17] The fault was found to be due to thermal fatigue cracks, requiring the other Trafalgar-class boats, and some of the remaining Swiftsure-class boats, to be urgently inspected and if necessary modified.^[17]"

"In 2013 the [UK] Defence Nuclear Safety Regulator [of "nuclear hazards"] reported that the reactor systems were suffering increasing technical problems due to ageing, requiring effective management. An example was that [HMS] Tireless had had a small radioactive coolant leak for eight days in February 2013.^[18]"

4.  Apparently less than 10 postgraduate nuclear engineers a year are trained in Australia for defence and civilian roles. This is expected to escalate into 100s of Australians needing to be trained yearly to meet submarine reactor inspection and maintenance safety needs.