Design Basis Threat

What is a Design Basis Threat (DBT)?

IAEA defines a DBT as: "the attributes and characteristics of potential insider and/or external adversaries, who might attempt unauthorized removal or sabotage, against which a physical protection system is designed and evaluated" (NSS-13). A DBT is a statement of the intentions and capabilities of an adversary or adversaries that could be considered a "worst-case credible threat" to a nuclear facility. The DBT is used as a basis for on which relevant nuclear facilities in Australia design and implement physical protection systems in order to defeat an adversary with clearly defined capabilities. DBTs are analogous to design basis accidents on which nuclear safety systems are designed.

Why use a DBT?

The IAEA's document NSS-13 "Recommendations on the Physical Protection of Nuclear Material and Nuclear Facilities" states that a State's physical protection requirements should be based on a design basis threat, especially where malicious acts could cause high radiological consequences.


Australia has used DBTs as an assessment tool since 1990. The historic focus of previous Australian DBTs was Australia's 10 MW High Flux Reactor (HIFAR) and its associated fresh and spent fuel, especially given that the reactor used highly-enriched uranium except in its final few years of operation. By the time of the most recent DBT review initiated in late 2011, all of the HEU fuel from the reactor had been repatriated leaving the new 20 MW LEU-fuelled OPAL reactor as the facility of highest potential radiological consequence.

How was the latest DBT established?

Broadly using the IAEA nuclear security guidance document titled "Design, Use and Maintenance of the Design Basis Threat", ASNO worked with a number of other Australian Government agencies, including the Attorney General's Department, the Australian Security Intelligence Organisation, the Department of Defence, the Australian Radiation Protection and Nuclear Safety Agency, and the Australian Federal Police to review the existing DBT in the context of the current threat environment. The process took about seven months to complete with the Director General of ASNO approving the latest revision in June 2012.

The process took about seven months to complete with the Director General of ASNO approving the DBT in June 2012. A mid-term review of the DBT was conducted in 2017 with a revision issued on 9 June 2017.

Why an unclassified version?

Due to the sensitive information a DBT contains, it is a classified document and only accessible to those closely associated with the protection of nuclear facilities. As a matter of transparency and accountability, to show that Australia's research reactor is protected against high-level threats, ASNO has produced a publicly available version of the DBT. The resultant unclassified version is necessarily general in nature.

Does any other country release an unclassified version of its DBT?

Yes. The United States Nuclear Regulatory Commission publishes an unclassified version of its DBT in its code of federal regulations 10CFR Section 73.1(a).

Further information:

Last Updated: 27 September 2016