Inspection report  
Licence holder ANSTO Opal Reactor
Location inspected Lucas Heights
Licence number F0157
Date of inspection 15 and 16 September 2022
Report number R22/08751

An inspection was conducted as part of ARPANSA’s baseline inspection program to assess compliance with the Australian Radiation Protection and Nuclear Safety Act 1998 (the Act), the Australian Radiation Protection and Nuclear Safety Regulations 2018 (the Regulations), and conditions of source licence F0157. 

The scope of the inspection included an assessment of ANSTO Opal Reactor's performance at Lucas Heights against the Performance Objectives and Criteria (POC) in the following areas:  Configuration management; inspection, testing and maintenance, and cross-cutting areas of culture for safety, human performance and performance improvements. The inspection consisted of a review of records, interviews, and physical inspection of the facility. 


The OPAL facility is a 20 MW multipurpose research reactor that provides a variety of benefits to the community including production of radioisotopes for nuclear medicine and neutron scattering research. The main codes and standards applicable to this facility are those that appear in section 59 of the Regulations plus AS 2243.4:2018 Safety in laboratories ionizing radiation.


The configuration management, inspection, testing and maintenance areas were found well managed. The reactor operation remained within the constraints of safety case with appropriate safety margins. Modifications to the safety related systems and general maintenance of the facility were observed to be appropriately managed and well documented. The licence holder was found to be in compliance with the Act, the Regulations, and licence conditions. 

However, three areas for improvement were identified. 

Configuration management

Several event investigations were reviewed and progress of actions arising from them were checked. OPAL event GRC 11580 involving contamination of two members of the OPAL maintenance team was inspected in detail. While the Heavy Water Upgrade System was being prepared for a valve replacement, two technicians inadvertently broke a seal of a valve whilst investigating if it could be opened manually rather than electrically. The hands of the technicians were splashed with a small amount of tritiated heavy water and elevated tritium levels were detected in the air within the room. The investigation was comprehensive and identified several lessons learnt and nine actions to prevent similar incidents occurring in the future.   

A check of all actions addressing the recommendations showed that almost all have been completed. Some administrative measures and installation of a protective glove dispenser in the area remain pending. The action prioritisation appeared appropriate and the most important actions, such as the improvement of instructions and training had been completed and a replacement tritium monitor/alarm had been purchased and was due for installation.

As reported to ARPANSA under event GRC 11932, the licence holder applied Surveillance Requirement SR 3.0.3 of the OPAL Operating Limits and Conditions (OLC) in November 2021. Surveillance requirements are usually a calibration, operational test, or measurement to ensure that a reactor system is functioning correctly and which, in turn, ensures that the reactor is working within its ‘safe working envelop’ as defined by the safety case. This clause allows the operator, under certain conditions, to extend the period of a surveillance requirement if it was unknowingly missed without declaring a non-conformance with the OLC. Meeting all OLCs and their surveillance requirements are important licensing requirements.  ANSTO has systems in place to prevent that, which have helped ensure that the use of SR 3.0.3 is rare event (four occasions in 16 years). All use of SR 3.0.3 is reported to ARPANSA and its frequency of use is also an internal safety performance indicator. In this case, SR 3.0.3 was invoked when the 35-day surveillance requirement to carry out chemical tests of the reactor pool water was missed by 2 weeks. It was found that SR 3.0.3 was used for genuine reasons when, due to a staff absence, responsibility for the work was transferred to alternative personnel that did not appreciate the full testing practice usually undertaken. Once identified, the missed surveillance requirements were immediately conducted, and precautions have been taken to prevent its recurrence. The incident highlighted the need for effective work instructions which reflect actual practice and the need to avoid an over reliance on any single person to conduct tasks.  

Any abnormal events or near misses that occur at the facility are logged in the organisation-wide electronic GRC system. The system allows event tracking and management including event categorisation, triaging and records the investigation result. ANSTO has established and maintained a good reporting practice at OPAL. Although some events have been found open for several months, they have been appropriately sorted and all events with safety implications have been acted on within a reasonable time frame. In reviewing the OPAL GRC listing, it was noted that the OPAL leadership had raised positive events where workers had taken proactive, conservative actions as a way of recognising good/safe behaviours.

The event management system allocates the following event categories: safety, environmental, quality, operations, and security. The process follows several organisation level protocols (e.g. AI-6865 and AI-6869) and OPAL instruction OI-02. It was observed that some events examined were not categorised as ‘safety events’ despite having safety implications. ANSTO explained that event categories are chosen based on the dominant type of the event that may not always fully describe nature of the events. The category is determined by the event notifier and the system does not support changing the event category throughout the process if it is later found miscategorised. It is noted that events are managed and investigated not based on their category but on the risk matrix described by the corporate document AG-2395. ANSTO acknowledged shortfalls of the GRC system such as inability of assign multiple categories to an event and a project to upgrade and replace the system is underway. Appropriate categorisation of incidents with safety implications is considered to be important to corporate oversight and organisational learning for safety. Above OPAL, ANSTO has overarching organisation business units with responsibility for workplace health and safety, radiation protection and nuclear safety.  The proper categorisation of the safety incidents is important for data analysis and trending both within the OPAL business unit and further afield. Categorising safety incidents as operational incidents, which was observed, may impede these functions. It was identified that the guidance to users on how to select event category should be improved and the appropriate categorisation of safety events should be proactively monitored by Management. ANSTO should also ensure that the process of categorising safety events is not a disincentive compared with other event categories. This forms an area for improvement.

Outstanding Interlock/Inhibition/Bypass Permits are registered and listed in the Shift Manager Logbook. Several entries were examined and reasons for the permits questioned. The licence holder provided evidence justifying the permits. Some of the entries were logged years ago. Projects exist to address the matters but due to low safety significance the projects have not been completed.  

The inspection involved a walk around the facility. The inspectors visited the reactor hall where a hot cell entry was under preparation. The team sighted the safe work method and environmental statement prepared and signed by all participants. Several pieces of clear plastic were sighted in the reactor hall. Clear plastic, if it enters the reactor pool, may be difficult to see in the water and has a potential to impede cooling of the reactor fuel if it is drawn into the pool cooling circuit. Whilst none of the plastic was within the restricted zone around the pool (according to OPAL instruction OI-22) some were loose and had not been disposed of as required by the instruction. It was recognised that the reactor was preparing for a periodic maintenance shutdown and several work activities were going on. However, the care for loose items near the pool vicinity should be maintained particularly during high activity times and housekeeping practice could be improved. This is an area for improvement.

Inspection, testing and maintenance (ITM)

Maintenance aspects of event GRC 11580 (also discussed above) were examined. The valve that was due to be replaced was part of the original Heavy Water Upgrade System design and was the only one of its kind at OPAL. ANSTO’s intention was to replace the valve with a more suitable and familiar design. The documentation for the valve was not complete and therefore the technicians were not familiar with the design. As a consequence, in removing what looked to be a plastic cover, they inadvertently broke into the heavy water circuit, briefly releasing a spray of water. The lack of information available to the technicians, at that time, was not a common problem and the Inspectors did not identify any systemic shortfall. Since then, the valve and all other valve of similar design have been replaced in the reactor facility. 

The event investigation identified that both technicians did not fully appreciate hazards associated with contamination with tritiated heavy water and did not have sufficient knowledge on how to manage the hazards. A similar contributor - shortfall in the hazard/consequence awareness - was also identified in other events, such as GRC 10362. Although that event was not directly related to maintenance, this common finding is raised now as an opportunity for improvement. 

A selection of maintenance related events was examined. The implementation of actions arising from the investigations was found generally timely and no major issues were identified. 

The last inspection identified an area for improvement that related to consideration of independent assessment of the OPAL ITM program. The licence holder indicated that there is no specific plan for a systematic independent review. However, the maintenance is scrutinised during Periodic Safety and Security Review (PSSR) of the OPAL reactor that is required every 10 years. In addition, the OPAL maintenance team participate in frequent peer fora (e.g. Bluescope Steel, Sydney Water, Transport NSW) during which maintenance programs are discussed and operational experience shared. Moreover, maintenance is also an integral part of the periodic cooperation between research reactor operators in South Africa, the Netherlands and ANSTO. These arrangements are considered useful for the OPAL maintenance and are deemed to acceptably address the IAEA guidance. 

The OPAL maintenance backlog for safety category 1 and 2 components was inspected. Items of the backlog with the highest potential to affect safety were selected for in-depth scrutiny. All those items were presented with sufficient evidence providing clear explanation for the respective maintenance delay. No items in the backlog were found to adversely affect safety. It is noted that this maintenance backlog list contained fewer items compared to previous inspections and this represents improvement. Only a few items were found to be more than 9 months overdue and all of them well documented and justified.


The licence holder was found to be in compliance with the requirements of the Act, the Regulations, and licence conditions. 

The inspection revealed the following areas for improvement:

  1. The categorisation of events to ensure that those with safety implications are labelled as “safety” rather than alternatives, e.g. Operational
  2. General housekeeping practice in the reactor hall.
  3. Worker awareness of task related hazards and their potential health consequence.

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