The secret of VVER upgrade success

30 March 2001

The success of VVER modernisation projects mainly depends on understanding cultural differences and being able to accept different philosophies and traditions.

Modernising an operating power plant is far more challenging than constructing a new one. Upgrading VVER plants has therefore been one of the most difficult tasks facing the nuclear industry in recent years. The nuclear division of Siemens’ Power Generation Group (KWU) – now part of Framatome ANP – has learnt many lessons from executing such projects, mainly over the last decade, in all countries with VVER plants.

At first glance it would always seem easier to modify existing equipment than to manufacture new components. However in practice it is much easier, and more satisfying, to produce a new piece of equipment based on an already existing design than, for example, to try to make an existing component work differently.

Activities and Lessons Learnt

Siemens have found that successful modernisation of plants equipped with pressurised water reactors of Russian design (VVERs) depends on a number of factors that have arisen during the course of many projects at various plants and within different cultures. In this context modernisation is used as a synonym for modification, backfitting, upgrading, reconstruction, harmonisation, life extension or whatever term one happens to prefer for projects involving studies, the implementation of improvements and/or the replacement of equipment.

The key lesson from all of these activities is that the success of a modernisation project is hardly threatened by issues of a technical nature. Instead, what really plays a decisive role is whether tasks and people can be managed effectively using efficient paths of communication.

Although this sounds perfectly obvious and logical, it nevertheless requires a high degree of professionalism. A vital role is played by “soft”, or non-technical, issues such as cultural backgrounds, the spirit of a project, the ability to stick to decisions once taken, the locations at which work is performed, and the existence or lack of standardised procedures, even for simple things. If a project management is not in the habit of constantly focusing on such factors, technical and commercial solutions can not be implemented. Siemens applies its experience acquired from managing several complex projects in a way that is specifically tailored to the needs of its national partners.

Siemens’ VVER projects

Siemens’ co-operation on VVER projects started in 1970 with the introduction of Siemens I&C technology at Loviisa in Finland, which was later followed by similar activities at many other VVERs. Then, in the 1990s, two situations resulting from German reunification enabled Siemens to familiarise itself very quickly with Russian technology. Firstly, there was an immediate need to analyse VVER plants located in its own country. Secondly, reunification also provided an opportunity to employ native German speakers who had studied in Moscow and were experts on VVER technology.

Activities for VVERs can be divided into four groups.

The initial stage involving conceptual studies and theoretical recommendations makes up the first group. This includes a wide variety of generic studies as well as material, thermodynamic and seismic analyses aimed at identifying deficiencies and deviations from current standards.

The second group covers the installation of equipment and components to reduce risk. Damage can be detected early on by modern remote-controlled tools and software for nondestructive in-service examinations. Training courses for maintenance personnel as well as the promotion of partnerships and meetings between eastern and western plant operators also belong to this more practically oriented group of activities.

The objective of the third and most expensive group has been to improve safety by upgrading and/or replacing existing components. Depending on national financial, geological and technological resources, this group includes such fields of activity as radwaste treatment, I&C, fire protection, valves and piping, emergency power supply and equipment for controlling the effects of natural and man-made hazards.

Finally, the fourth group is related to the mitigation of beyond-design events. These activities include hardware backfits such as hydrogen recombiners and filtered containment venting systems. Also in this category are software upgrades such as the generation of detailed operating procedures and the training of personnel on plant simulators.

Roughly half of all of these activities have been performed by Siemens in close co-operation with companies based mainly in France, Spain, Belgium, the United Kingdom, Russia, Slovakia and Italy. The projects were executed either within a consortium, by a joint venture or with Siemens acting as a subcontractor. Most of the financing for these activities came from the EU (TACIS, PHARE, EBRD and EURATOM) but some funds were also provided by governmental agencies and western utilities.

Project phases

As regards the third and most effective group of activities it is essential to first look at some historical facts.

One of the main challenges in any VVER modernisation project results from the different approaches to previous technical projects in free market economies and in centrally planned economies. In free markets people were used to project phases such as conceptual design, basic and detailed engineering to clear tender specifications, and a subsequent bid evaluation phase.

However, in planned economies the suppliers were already fixed from the start. Their local know-how was incorporated into the projects from an early stage without any need for competition and was mostly based on a uniform Russian design. Therefore, following only a very short phase for defining the overall task of the project , the task definition phase, the national general designer (known as Energoprojekt or EGP in almost all of the eastern European countries) started on the next phase of the project – the so-called introductory phase – which comprised detailed engineering work with direct involvement of the various national suppliers. The degree of detail required during this phase for licensing and state planning purposes was similar to that of the detailed engineering phase in market economies.

Component manufacturers could easily go ahead and invest in detailed design work because they were sure to be awarded the corresponding supply contracts. Western suppliers, on the other hand, are naturally hesitant to generate detailed designs at the bid preparation stage. The original Russian approach sometimes used the term technical project to denote a phase which covered both the introductory phase and a large portion of the subsequent implementation phase. This meant that there was practically only one phase covering the entire range of activities from task definition to implementation.

Another aspect to be taken into consideration is that VVER licensing requirements and contract award procedures were based for many decades on the construction of new plants using well-known designs. What is needed now is adaptation of codes and standards as well as preparation of all engineering disciplines involved to meet the special requirements associated with the modernisation of individual parts of a power plant. This is all the more challenging since such projects also sometimes entail new man-machine interfaces which have to be accepted by the plant operators, who have been accustomed to using the same procedures and equipment for decades.

In order to overcome such cultural differences, it is also important to agree in advance on the content and relevance of project documents. For example, during the conceptual planning phase, a two-month time schedule for installation detailed right down to individual hours and prepared five years beforehand cannot possibly be seen as binding.

The first of the three project phases customary in the West, the planning phase, is much more finely structured and allows for various stages of bidding in order to arrive at an optimum solution. An understanding of the need for a professionally elaborated basic engineering phase is still very rare among VVER utilities. They are hesitant to invest between 10% and 20% of their total budget for the project just in planning and in the preparation of specifications for international competition. Siemens is convinced that the planning phase of a modernisation project is not the time to try to save money. Any attempt to cut down on expenditure at this stage is sure to lead to problems that will end up costing much more to rectify than the amount of money initially “saved”. In the end, investing in the planning phase turns out to be comparatively cheap since it provides greater flexibility and helps in assessing and, if necessary, improving how the remaining 80% to 90% of the overall project budget should be spent.

Models for co-operation

The success of a modernisation project does not depend only on concurring views about the scope of the individual project phases. It is also essential to agree on a suitable contractual model. The main parameters for selecting a co-operation model are the risks that can be borne by the customer and the extent to which national specialists can be involved. These factors have to be carefully analysed for each project, not only as regards plant design and project management but also with respect to financing, manufacture and installation. Once this has been done, efforts should be concentrated on defining a realistic scheme for splitting the work between the partners involved. The last step comprises working out a feasible plan for distributing the commercial risks among the individual partners and the customer.

The Figure shows examples of contractual models that have been accepted by Siemens for various modernisation projects based on different national circumstances. In practice, most projects turned out to be a mixture of two basic models. In one of these, the customer signs just one contract with a general contractor or a consortium (symbolised by a thick circle in the Figure), without bothering about interfaces and detailed schedules. In the other model, the customer awards multiple contracts and manages the scope and sequence of individual tasks himself. At first glance, this multiple-contract model would seem to be less expensive for a utility because it would be able to select the cheapest bidder for each individual task. On the other hand, none of the contractors would provide an overall guarantee for the final level of plant availability and safety. In cases in which the customer lacks experience or his consultants are not assigned adequate responsibility, the gaps arising between individual tasks will lead to frustration on the part of those involved and finally to a considerable delay in the start of commercial operation.

The implemented projects have therefore comprised a mixture of these two models and have been heavily dependent on the utility’s management skills. In this connection it is important to emphasise that taking over responsibility for project management is not only a question of available manpower. Being responsible for management of the project also means assuming overall responsibility and bearing all risks and financial consequences arising from mistakes, deficiencies or unforeseen problems for which the subcontractors are not responsible.

Therefore one of the main prerequisites for selecting a suitable co-operation model for a modernisation project is to conduct a thorough basic engineering phase which correctly identifies all interdependencies existing between small and large improvements in the plant. Describing around 80% of these interdependencies may appear fine, but even 90% is in no way sufficient. Interdependencies which have not been identified will result in errors, deviations, delays and additional effort. This underscores the fact that technical issues hardly threaten the success of a modernisation project with international partners.

In most of our consortiums and joint ventures with national partners for VVER plants we ended up having to adapt the way we had split up the work in order to comply with the schedule originally agreed with the utility. It is the cultural differences that require continuous attention and adaptation, regardless of the size of project – especially when a plant has been operating smoothly for several decades. Although appropriate involvement of national specialists is indispensable, a successful project nevertheless requires a joint understanding of all issues along with a sound contractual basis.

Digital I&C for VVERs

In the 1990s the positive experience gained in Finland with the application of Siemens' safety-related and operational I&C for VVERs was able to be repeated at Slovakia's Mochovce 1&2. These units’ good performance is proof that eastern and western equipment and engineers have been able to form a useful synergy for ensuring safe and reliable operation of power plants designed many decades ago. During this time Siemens also performed numerous studies and partial I&C replacements at plants built both by Siemens and by other vendors.

Based on this broad experience the next challenge was to instal digital I&C in VVER-440 plants of the first and second generations: namely, at Bohunice V1, 1&2 (Model 230) and at Paks 1-4 (Model 213). The contracts for these projects were all awarded in 1996. Two of these units have been successfully operating with their new digital safety I&C for more than one year now. Another two went back on line last summer. Paks 3 and 4 will be restarted with their new digital I&C in 2001 and 2002.

All plant startups were trouble-free and no major problems have been encountered during subsequent operation thanks to the fact that the following six prerequisites – which apply to all such projects – were met by the specialists involved:

1. Product development in co-operation with operators and authorities

An essential factor here has been the adaptability of both the configuration and the hardware of our digital safety I&C platform TELEPERM XS (TXS) to VVERs. The TXS platform, which was developed more or less independently of any specific type of reactor technology, has thus passed its first practical test.

2. Description of full scope of work

A clear description of the full scope of work that covers all aspects involved in implementing TXS at an existing plant is indispensable. This work does not just consist of replacing cabinets. Apart from various physical requirements such as dimensions and weights, consideration must also be given to sources of power supply, to environmental and seismic conditions, and to electromagnetic compatibility. A new redundancy concept could result in modifications having to be made to the building structure. Also, parallel operation of the old and new I&C for a certain period of time might require the provision of additional power supplies and systems for heat removal.

3. Concept for sensors and signal sharing

Maintenance work and thus maintenance costs can be considerably reduced by cutting down on the number of sensors. This entails having an intelligent concept for the sharing of signals. Also, the space available for installing new cables in addition to the existing ones might be limited.

4. Generic qualification

Licensing effort has been able to be minimised through generic qualification of I&C equipment, for example by the US Nuclear Regulatory Commission (NRC), and through type-testing of both hardware and software based on international licensing requirements. Factory acceptance tests then ensure that all features required for a specific plant are provided.

5. Replacement within a short period of time

Replacement of I&C within a short and clearly defined period of time is guaranteed by a detailed schedule for execution prepared through close co-operation between experienced professionals. For example, cable connections have to be prepared in advance as far as possible. Also, planning of the comprehensive factory acceptance tests must incorporate adequate reserves in order that the tests can be finished in time.

6. Optimised training programmes

Finally, the plant’s operating and maintenance personnel have to accept the digital I&C. Involvement during the engineering phase, easy-to-use data processing and documentation tools as well as on-the-job training during installation and startup ensure that the new equipment will be operated and maintained carefully and properly.
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