The information on this page relates to foreign nuclear-powered vessels that visit Australian ports.  


Port visits to Australia by naval vessels of allied nations, and reciprocal visits by ships of the Royal Australian Navy, are one of the most visible aspects of the defence cooperation between Australia and other countries in peacetime. These naval vessels may be conventionally or nuclear-powered.

Due to the nature of Nuclear-Powered Vessel (NPV) propulsion plants, special procedures have been adopted to ensure that the safety of the public and environment is maintained during visits by such vessels. 

An interdepartmental government group, known as the Visiting Ships Panel (Nuclear), oversees these visits – more information about that below. This committee has established procedures to ensure the public and the environment’s safety during visits from nuclear-powered vessels. These procedures include conditions of entry to the port, radiation monitoring, and contingency arrangements in the unlikely event of an incident resulting in the release of radiation to the environment.

The radiation monitoring program is designed to detect any radioactivity release to Australian ports, the surrounding environment, and any increase in external radiation levels above those due to natural background radiation.

Radiation monitoring program

The radiation monitoring program has two main objectives:

  1. ensure that the early warning monitoring systems and emergency procedures are in place before any visits and;
  2. provide environmental monitoring after an incident to detect the release of any radiation to the environment

Sensitive, high volume seawater monitoring and analyses is undertaken in the vicinity of the vessel after visits to verify there have been no environmental releases of radiation.

A radiation monitoring system is in place during each nuclear-powered vessel visit to provide early detection of any release of radiation to the environment. This early warning system is complemented by arrangements for notification by the nuclear-powered ship should an incident occur.

The nuclear-powered vessel radiation monitoring program results are published annually by the Department of Defence:

The Reference Incident for nuclear-powered vessels

Much of the Commonwealth Government’s planning for managing potential radiation exposures is based on the ‘Reference Incident’ detailed within the 2000 Reference Accident report. The Reference Incident refers to a hypothetical scenario for a severe accident involving a nuclear-powered vessel, which results in the release of radionuclides from the ship’s nuclear reactor. 

A single incident was chosen to represent an upper bound risk to the surrounding population. This scenario is a loss of coolant accident in a nuclear-powered vessel reactor and the subsequent release of radiation to the environment. 

In the modelled incident, radiation released from the vessel becomes airborne and is transported as a cloud or ‘plume’ through the air. As this radioactive cloud passes the principal method of exposure is through inhalation of radiation and external irradiation. Some of the airborne material will deposit on the ground as the cloud passes and will continue to present a radiation hazard. After the passage of the radioactive cloud, the two principal methods of exposure would be through external irradiation and from ingestion of radiation. Resuspension of surface contamination and the subsequent inhalation would be very small. 

The Reference Incident also predicts that the major component of the release would be radioiodine, with the initial levels of caesium-137 (Cs-137) contamination predicted to be at least an order of magnitude lower than the initial radioiodine levels. Both Cs-137 and radioiodine contamination can move easily into the environment, and this indicates that all foodstuff produced in the affected area, particularly milk would need to be monitored closely to ensure that the radiation dose to members of the public is minimised.

We have published a fact sheet on our website about nuclear-powered vessels as a radiation source on our website.

Visiting Ships Panel (Nuclear) VSPN

The Commonwealth Government has established an interdepartmental standing committee called the Visiting Ships Panel (Nuclear) (VSP(N)) to control arrangements for visits to Australia by nuclear-powered vessels.  

These arrangements are detailed in the Department of Defence’s Defence Operations Manual (OPSMAN1) - Visits to Australia by Nuclear-Powered Warships.

The responsibilities of the VSP(N) are to:

  1. advise the Minister for Defence on proposals for nuclear-powered vessel visits
  2. develop and maintain procedures related to nuclear-powered vessel visits
  3. oversee the implementation of specific arrangements, especially safety requirements, for visits by nuclear-powered vessels
  4. maintain and oversee safety arrangements for visits by nuclear weapons capable vessels
  5. validate/invalidate all nuclear-powered vessel ports on advice from the Technical Working Group of the Visiting Ships Panel (Nuclear).


OPSMAN1 provides detailed information on the conditions, procedures, and the responsibilities for the visits by nuclear-powered vessels to Australian ports. Visits are only permitted to Australian ports that have been assessed and approved as suitable in terms of strict environmental and safety criteria. Conditions of entry to Australian ports by visiting nuclear-powered vessels have been established by the Australian Government. In the event of a reactor-based incident, procedures are in place to remove the affected vessel from the port'

ARPANSA, the Australian Nuclear Science and Technology Organisation (ANSTO) and the Australian Defence Force are the main Commonwealth agencies providing radiological support to the emergency plans. 

The immediate monitoring response to a nuclear-powered vessel incident is provided by local Radiation Monitoring Groups, comprising State radiation health, emergency services personal or navy reservists under the direction of an ANSTO health physicist. ARPANSA provides the early warning system, personal radiation monitors and analyses marine samples. In the event of a nuclear-powered vessel incident, ARPANSA may be also requested to provide additional teams and the Commonwealth Technical Advisor to support the State response through the Commonwealth Disaster Plan. 

The objectives for the conduct of emergency radiation monitoring for nuclear-powered vessel visits are to:

  1. provide accurate and timely data on the level and degree of hazards resulting from the release
  2. provide detail of the physical and chemical characteristics of the hazard
  3. determine the extent and duration of the hazard
  4. assist decision makers on the need to take protective actions based on pre-defined measurement thresholds called operational intervention levels 
  5. confirm the efficiency of remedial measures, such as decontamination procedures
  6. assist in preventing the spread of contamination
  7. provide information for incident classification
  8. provide information for protection of emergency workers

ARPANSA aims to address these objectives in the context of a radiation release associated with a visiting nuclear-powered vessel in an Australian port. The Environmental Monitoring Handbook for Visits by Nuclear Powered Warships Part A Monitoring for Post Accident Recovery (below) provides the recommendations on procedures for sample collection and analysis and the basis for the training of the relevant monitoring teams. More extensive monitoring of affected areas would be conducted following an incident. This could continue for several days, weeks or months, depending on the extent of the release.

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