Processes
Life Cycle of a Nuclear Facility and Licensing
The scope and content of the services provided by TÜV NORD Nuclear in the field of nuclear safety is determined by the licensing environment and varies with the individual stages in the life cycle of a nuclear facility.
The stages in the life cycle of a nuclear facility encompass
- Planning,
- Product Realisation: Construction & Erection,
- Product Realisation: Commissioning (TQC),
- Operation,
- Decommissioning.
Typically, the life cycle stages are accompanied by a respective licence
- to construct,
- to commission,
- to operate,
- to implement a "large-scale" plant modification or
- to decommission.
From the legal perspective, licensing is a prerequisite for any action to be taken in the construction & and erection, commissioning, operation and decommissioning stages of a nuclear facility. Only in the planning stage, licensing is not directly related to the actions taken; however, in this stage the ensuing licensing stages in the life cycle are prepared. This means that licensing and the related activities accompany a nuclear facility throughout its entire life cycle.
The detailed regulatory requirements to be considered during the life cycle of a nuclear facility depend on the licensing environment which is specific for each country. However, the principal features of the processes governing the life cycle follow a generic logic, which is in such a way universal that it can be applied to any nuclear facility. This means that it is equally applicable e.g. to nuclear power plants, facilities of the nuclear fuel cycle or repositories for the final disposal of radioactive waste. The generic logic governs the actions to be taken both in full-scale activities – e.g. the erection of a nuclear facility – or in partial activities – e.g. modifications of the plant design or components.
Any stage in licensing is split into two distinct phases: The application for a licence and its implementation. The application phase aims at a licence being granted, whereas the objective of the implementation phase is to enforce the scope and content of the licence, once it has been granted. This implies that during a specific licensing stage in the life cycle of a nuclear facility, granting a licence is kind of a milestone. Usually, safety assessment is allocated to the application phase and is therefore a pre-licence activity, whereas reviews and inspections are typical topics of the implementation phase and accordingly are understood as typical post-licence activities.
TÜV NORD Nuclear Competences in Safety Assessment
Safety assessment, reviews and inspections are integral parts of licensing and require specific competences. These activities are performed under the responsibility of the regulator, of the licensee or – in parallel – of both of these parties, depending on the licensing environment in the respective country.
TÜV NORD Nuclear offers integral or partial safety assessment, review and inspection services in all stages of the life cycle on behalf of the regulator or the licensee. On behalf of the plant supplier, TÜV NORD Nuclear offers engineering services, which are not necessarily directly related to licensing. The aforementioned TÜV NORD Nuclear activities are performed under the terms of appropriate safety and quality management systems.
The expertise of the staff at TÜV NORD Nuclear is covering the whole range of competences and experience required to perform the full scope of safety assessment and reviews. TÜV NORD Nuclear has access to all tools which are required for performing safety assessment and reviews. Among these are e.g.
- the computer codes used for assessing the safety analyses,
- the respective codes for performing probabilistic safety analyses,
- the computer codes used for performing stress and fatigue analyses,
- the codes for evaluating the neutronic and thermo-hydraulic core design as well as the thermo-mechanical fuel design and
- the statistical data bases for evaluating the operation records as part of the periodic safety reassessment.
The inspections are performed by adequately trained and experienced independent inspectors and extend to all areas which are relevant for the safety of a nuclear facility during all stages of its life cycle. TÜV NORD Nuclear cooperates with a TÜV NORD subsidiary specialised on the application of the ASME Code. In total, the TÜV NORD Nuclear inspectors are familiar with the applicable codes and standards due to their frequent involvement in inspection tasks and are ready to adapt to new challenges.
By means of a stringent project management, specific care is taken that during all stages of the life cycle the interfaces between the different engineering and scientific disciplines involved in the activities are identified reliably and considered to the necessary extent in the specific tasks.
The TÜV NORD Nuclear competence reflects the experience gained by today more than 550 experts in the licensing of 12 nuclear power plants in Germany, research reactors and numerous facilities in the nuclear fuel cycle. Apart from this, TÜV NORD Nuclear is crediting its experience gained in various licensing and supervision activities abroad. The operational record of the plants under the supervision of TÜV NORD Nuclear amounts to more than 300 operational years. This figure includes the TÜV NORD Nuclear contribution to both German and international projects.
Safety Assessment, Reviews and Inspections
Safety assessment establishes the safety-related technical and procedural framework to be considered when the li-censed measures and steps will be implemented. Furthermore, it aims at verifying that the full scope of the applicable safety requirements is actually considered in the application for the licence and will be transferred appropriately into the implementation phase. This includes credibility that it will actually be possible to design, construct, commission and operate etc. as per the licence in the ensuing implementation stage.
If such expectation cannot be confirmed from the outset, e .g for design changes initiated by the licensee licensing con-ditions imposed by the regulator will ensure that such basically unintended deficiencies will be removed. The information to be evaluated in safety assessment is submitted in the Safety Case and Supporting Documents. The Safety Case supplements the formal application for a licence and aims at justifying the application.
The term reviews and inspections stands for all licence-related actions taken after the licence has been granted. The focus of these actions is to verify that the procedural and technical scope as stated in the licence is fully considered in the implementation phase. This can be achieved by either applying analytical tools in the review part or by performing shop inspections, on-site inspection during construction & erection or operation supervision etc. The information which serves as a basis for the reviews and inspections is provided by the licensee in appropriate documents, like e.g. detail design documents, inspection plans, operation records etc. Non-achievement of the applicable requirements is not acceptable. In such situation, corrective actions, like redesign, rework etc. would be initiated.
