While most discussion of the AUKUS Agreement has focussed on the geopolitical implications for Australia’s standing in the world, the escalation of the risk of war and the crippling cost of the nuclear submarine purchases when less expensive and more sensible non-nuclear options are available, little has been said of the risk to the civilian population posed by these nuclear-powered submarines (or other nuclear-powered naval vessels) in Australia’s home ports.
Perhaps we citizens only enter the calculations as ‘collateral damage’. Any such necessarily technical discussion is hampered by military secrecy. Some information has been released officially, but most is from generalised inference, or conjecture, and so subject to uncertainty. However, in this important matter, it is worth attempting to join the dots….
News from the war in Ukraine includes, almost every other night, a report on the situation around the Zaporizhzhia Nuclear Power Plant, the largest in Europe. Though no longer continuing to generate power for Ukraine, it is always at risk of being shelled or bombed by one side or the other, and regularly just avoiding reactor cooling water pump failure from damaged power transmission lines or lack of diesel fuel for their backup generators for the pumps. How long this situation will continue remains to be seen. And now, after the breaching of the Kakhovka Dam, it is estimated just three months of water for cooling remains.
The consequences of the catastrophic failure of a nuclear reactor are well known to both the Ukrainians and the Russians. To the Northwest of Zaporizhzhia, and just 100 kilometres North of Kyiv, lies the Chernobyl Reactor No. 4, which, on 26 April 1986, underwent meltdown after a coolant and moderator failure, exploded, and caught fire. Radioactive material and fission products were ejected into the air, spreading across the immediate countryside and into Northern Europe. Radioactive rain was reported on the mountains of Wales and Scotland, in the Alps, and contamination in reindeer herds in Northern Sweden. The principal radiological contaminant of concern across this vast area was Caesium-137, one of many fission products and representing some 6% of fission reactor spent fuel. Just 27 kg of Caesium-137, it is calculated, caused this contamination. Some 150,000 square kilometres of Ukraine, Belarus and Russia were initially contaminated. Of course, at the time of the accident, all this was part of the Soviet Union. To this day, 2600 square kilometres around the plant are considered unsafe for human habitation, or agriculture, and will remain so for between 300 and 3000 years! The Reactor used 2% enriched Uranium fuel.
Although the loss of life at Chernobyl was a small fraction of the 100,000 deaths from one of the only two uses of nuclear weapons in war, on Hiroshima in 1945, Chernobyl created 400 times more radioactive pollution. The Hiroshima bomb, “Little Boy”, contained 64 kg of enriched Uranium, though less than 2% actually underwent nuclear fission. The bomb was detonated 500 metres above ground (‘airburst’), and the fatalities were the result of blast, heat, and irradiation, in a city centre. Chernobyl occurred at ground level and so ejected debris upwards initially, followed by smoke columns from subsequent fires. The 31 deaths at Chernobyl were plant operators and, of course, firemen. The G7, the AUKUS Partners and the Quad just met at ‘ground zero’ in a rebuilt Hiroshima City, 78 years after the bombing.
The US Navy nuclear powered warships, including the ‘Virginia’ Class submarines that Australia would buy under the AUKUS Agreement, principally use Highly Enriched Uranium (HEU) reactors. The Uranium is enriched to above 93% fissionable Uranium-235. It is weapons grade material and has in part been sourced from decommissioned nuclear weapons. The submarine reactors are intended to last for the ‘Life of Ship’ (LOS), up to 33 years, without needing refuelling. Low Enriched Uranium reactors need fuel replacement every 5 to 10 years, when, importantly, the containment pressure vessel around the reactor is physically inspected for flaws and deterioration. This is not done for the HEU, LOS reactors.
The S9G nuclear reactor in the Virginia Class submarines is rated at 210 Mega Watts thermal (MWt). This is the heat energy generated by the fissionning of Uranium-235 (U-235), which heats the Pressurised Water around the reactor core, that then heats and boils separate water to create the steam, that drives the turbines, that drive the propulsors (ducted propellers), and also generate electrical power for shipboard use. The fissionning of each kilogram of U-235 generates 940 MW days of heat, so for a 210MWt reactor at full power, 1 kg of U-235 would be needed every (940 ÷ 210 =) 4.5 days. In one year, at full power, (210 x 365 ÷ 940 =) 81.5 kg of U-235 would be required. Along with other decay products from the U-235 (Strontium-90, Iodine-131, Xenon-133 etc.), as noted earlier some 6% (or 4.9 kg) would be Caesium-137. The ‘neutron poisons’ also created are balanced out by ‘burnable’ neutron poisons incorporated into the core when new, to maintain reactor function over the years. So far, simple nuclear physics and thermodynamics.
Operationally, one surmises, the submarine reactor will infrequently run at full power. Actual annual production of Caesium-137 may lie between, say, 0.8 kg for 1/6th capacity operation on average for the whole year, and 2.45 kg at half capacity for the year. As the reactor is designed to not need refuelling for the ‘Life of the Ship’, the Cs-137 would continuously accumulate inside the reactor fuel elements. At the lower bound of 1/6th operation, there would be approaching 27 kg of Cs-137 in the core after 33 years, allowing for the decay of some of the Caesiun-137, given its half-life of 30.05 years. At the upper bound, it would take about 13 years for 27 kg of Caesium-137 to accumulate.
Visiting nuclear-powered submarines, from the US or UK, would be similar. Visiting US nuclear-powered aircraft carriers, each with two A1B reactors each of 700MWt, may have 27 kg of Cs-137 in their reactor cores after just two years of operation.
Visiting ships may stay in Australian ports for days or even weeks. Australian submarines will be in port not only between deployments, but also for maintenance, for months and years. The US Navy appears to have about 40 Virginia Class Subs, with some 18 undergoing long-stay maintenance, or about half. We might expect the same. So, at any one time, the AUKUS plan would see naval nuclear reactors, US, or UK, or Australian, or all, in Adelaide, and/or Fremantle, and/or Port Kembla. While peacetime only presents the risk of a nuclear accident, wartime would see these important military assets easily detectable – and targetable – while in port. In the event of a nuclear war, this may be just one of our worries. In a conventional, non-nuclear conflict, the story may be very different. The situation of the Zaporizhzhia civilian reactors in Ukraine is most instructive. However, as legitimate military targets, would such restraint be shown towards the reactors in the submarines? What would be the impact of a conventional cruise or hypersonic or ballistic missile warhead on the pressure hull and reactor containment vessel (and plumbing) of a nuclear-powered submarine?
Should just 27 kg of the Caesium-137 in the naval reactor cores be released into the air through an explosion (as at Chernobyl) in an accident or deliberate attack, what would be the outcome? In Fremantle, especially if the ‘Fremantle Doctor’ was blowing, would sections of Fremantle and Perth become unsafe for human habitation? In Port Kembla, especially if a ‘Southery Buster’ came through, the Illawarra and, depending on the particular weather conditions, would parts of the South of Sydney become unsuitable for human habitation? For Port Adelaide, especially if a NW change came through, would the Adelaide coastal strip from Gawler to Aldinga become unsuitable for human habitation?
Imagine the number of “single mums doing it tough” who would have to be relocated to emergency accommodation – somewhere! Imagine all that social housing rendered uninhabitable! Even if we ‘won’ the war.
This is a real possibility if we have nuclear reactors in surface ships or submarines in our ports, or in our ship building and maintenance facilities.
Douglas McCarty
Douglas McCarty, now retired, was formerly a Civil Engineer in Structural Design and Construction, a Secondary School Teacher of Physics, General Science and Mathematics, and a University Tutor in Education at Flinders University. He is a rank-and-file member of the Australian Labor Party.