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Graphite Technical Advisory Committee


The Graphite Technical Advisory Committee (GTAC) is a group of independent academic experts and specialist consultants who provide technical assistance to support the Office for Nuclear Regulations (ONR) in carrying out its regulatory duties regarding the UK fleet of graphite moderated nuclear power stations. 

The committee provides independent and authoritative technical advice and expertise to the regulator on the scientific theories supporting the licensee’s graphite core safety cases. The graphite cores change and degrade with age due to irradiation - this is a technically complex area. The availability of such advice is strategically important to ONR, particularly as there are limited international norms to work from in this area as the design of the graphite moderated reactor fleet is unique to the UK.

The committee was established in 2003. It originally provided support to the graphite moderated Magnox and Advanced Gas Cooled Reactor (AGR) nuclear power stations.  The committee is now focussed on supporting the AGR nuclear power stations as the Magnox nuclear power stations have closed, but the experience gained from the earlier stations remains of use.

The committee enhances ONR’s role as an effective regulator of the nuclear industry, and compliments the other research activities it undertakes in the area of graphite degradation.

Terms of reference

The terms of reference for GTAC are to provide a source of independent technical advice to ONR on materials related issues concerning graphite for nuclear reactor applications.

GTAC composition

Chair: Professor Paul Bowen, FR Eng.

Technical Secretary: Provided by the University of Manchester

Independent Members: Seven independent members plus the chairperson.

Organisation and Structure of GTAC

GTAC is managed through a commercial contract with the University of Manchester who provide the necessary organisational and secretarial support to allow the committee to function. 

The committee consists of the chairperson, the ONR lead graphite inspector and the independent members.

The independent members are appointed by agreement between the ONR lead graphite inspector, the GTAC chairperson and the appointee. Selection is based on individual’s academic and professional capabilities, subject expertise, and their independence from the licensee. The chairperson and independent members of the committee are held in high esteem in their fields.

The committee is supported by a technical secretary, and both ONR and the AGR’s licensee may send representatives to committee meetings.

Governance arrangements

The work of GTAC is controlled through main committee meetings that typically take place four times per year. The meetings provide background and briefings on current issues, from both ONR and licensees. It is also the forum in which requests for advice are formally tabled by ONR.

Sub-groups are formed to address the requests for advice.  These sub-groups will meet as necessary between the main committee meetings. They will then report back on their findings to the main committee meetings.

Licensees may send representatives to GTAC meetings who may be direct employees of the licensees or contractors of the licensee who have specific knowledge or relevant input to items on the agenda. 

ONR sends representatives to GTAC meetings to better understand their thinking on the advice they have requested.

Guests may be invited to GTAC meetings, these may be specialists who have been subcontracted to assist GTAC answer specific points, observers from ONR or the licensees or others who may be of assistance to the committee.

Methodology for advice and decisions

The ONR lead graphite inspector formally requests advice from GTAC.  The topics for this advice are based on an understanding of the technical issues that are currently of interest in the licensee’s safety case, and issues which are thought to be of importance as the graphite core safety cases develop further.

The GTAC advice is written up in the form of a response to a question.  This advice is used as appropriate by ONR in assessing the safety cases provided by the licensee, and where that advice is used it is referenced within those assessments.  Significant graphite assessments are published on ONR’s website.

Regulatory decisions and technical guidance remain the responsibility of ONR inspectors.