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Increasing European networking around High Temperature Reactors
by Joël Guidez, Head of High Flux Reactor Unit, Westernduinweg 3, Petten, Netherlands
email: guidez@jrc.nl

In the January/February 2001 issue of Nuclear Europe Worldscan, an announcement was made on the creation of a European network of companies with interests in nuclear energy to study High Temperature Reactor Technology (HTR-TN).

In the 1980s, European companies were involved at the highest level in this technology, especially with the operation of the THTR-300 in Germany.

However, after the Chernobyl incident and a global decrease of public acceptance for the nuclear industry, this plant was shut down in 1988, and all HTR-related projects were more or less abandoned.

Comeback of HTR

The comeback of this technology – one of the most promising possibilities for the future – has come from several convergent directions.

Firstly, two new prototype reactors became critical in Japan (HTTR) and in China (HTR10), showing the high level of interest in these countries for this technology.

Secondly, in studies made by the US and Russia on the best way to burn military plutonium, the qualities of HTR in this field, led to the organization of the GTMHR project, which involves the US, Russia, Japan and European companies.

Meanwhile, in South Africa an industrial project, called PBMR was initiated with volunteer planning, also involving US and European companies.

If you add all these points, as well as a renewed interest for nuclear energy due to, for example, the greenhouse effect and the beginning of studies around generation 4, you can begin to understand better the enthusiasm for this technology.

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Modernization of VVERs: Lessons learned by western partners
by Franz Hilbert, Framatome ANP, Hammerbacherstrasse 12-14, Postfach 3220 Germany, Tel: +49 9131 189 2818
email: franz.hilbert@framatome-anp.de

The modernization of an operating nuclear power plant is a much more challenging task than the construction of a new plant.

In fact, it requires the same detailed preparations and skills as are needed for open-heart surgery.

Modernization activities and lessons

The engineers of Siemens nuclear division - now part of Framatome ANP - have been forced more and more to practice such "open-heart surgery"; i.e. to replace components within a fixed time schedule.

Cooperation on projects for VVERs started as early as 1970 with the introduction of Siemens I&C technology at Loviisa in Finland, which was later followed by similar activities at all VVERs, as shown in Figure 1.

Activities for VVERs can be divided into four groups.

Most of such activities have been performed in close cooperation with companies mainly from France, Spain, Belgium, Great Britain, Russia, Czechia, Slovakia and Italy.

The financing has been substantially from the EU (Tacis, Phare, EBRD, Euratom) but also from governmental resources and Western utilities.

The first group includes generic studies as well as material, thermodynamic and seismic analyses; i.e. theoretical recommendations aimed at identifying deviations from current standards.

The second group covers the installation of individual items of equipment to reduce risk, i.e. automated diagnostics systems, remote-controlled tools and nondestructive in-service examinations.

The objective of the third and most expensive group has been to improve safety by upgrading or replacing existing components.

This group includes such fields as radwaste treatment, I&C, fire protection, valves and piping, and emergency power supply.

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 as well as upgrades of operating procedures and training of personnel on plant simulators.

The main lesson that has been learnt with various partners from different cultures is that the success of a modernization project is hardly threatened by issues of a technical nature.

A vital role is played by 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 of standardized procedures, even for simple things.

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Nuclear Safety in Slovenia - the World Smallest Nuclear State
by Marko Cepin, Jožef Stefan Institute, Reactor Engineering Division, Jamova 39, 1000 Ljubljana, Slovenia
email: marko.cepin@ijs.si

The high level of nuclear safety in Slovenia is proved by a number of facts, which emphasize the following:

• The convention on nuclear safety is in force in Slovenia, following its signing and subsequent ratification by parliament several years ago.

• The primary responsibility for nuclear safety is borne by Krško NPP, which is independently supervised by the Slovenian Nuclear Safety Administration (SNSA) on all matters connected with safety.

• The designated technical support organizations, e.g. the Jožef Stefan Institute, independently assist and advise the Krško NPP and the SNSA.

The Jožef Stefan Institute also conducts a postgraduate program of nuclear engineering in collaboration with the faculty for mathematics and physics at the university of Ljubljana.

This integration of university teaching, research, development activities, expertise on nuclear energy, and safety questions ensure high confidence in Krško NPP safety.

Krško NPP was designed, built, and tested in accordance with the US AEC (Atomic Energy Commission, from 1975, NRC - nuclear regulatory commission) design and safety criteria.

The legislation in force in Slovenia required the application of US (as a vendor state) codes and standards in case of specific licensing activities for the Krško NPP.

Krško NPP operates in accordance with the Updated Safety Analysis Report (USAR), which complies with US NRC RG 1.70, standard format and content of safety analysis report for NPPs and IAEA safety series no. 34. It is regularly updated according to a written review procedure and is approved by the regulatory body.

It evolved from the Preliminary SAR, which was issued as a safety assessment made before the construction, and the Final SAR, which was issued before the beginning of operation.

A major plant modernization program with exchange of steam generators, power increase, and safety upgrading took place in 2000 and was subjected to a comprehensive licensing process.