Erfahrungs- und Forschungsbericht 2012 - Ensi

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Erfahrungs- und Forschungsbericht 2012 - Ensi

Summary

Research into regulatory safety

In the exercise of its regulatory responsibilities for

nuclear facilities, it is essential that ENSI acts upon

the basis of the latest developments in science and

technology. ENSI therefore supports and coordinates

safety research within its regulatory powers.

The results of that research influence directly its

Guidelines, individual decisions and resources. At a

more general level, research projects serve training

purposes and thereby maintain competence within

ENSI and its experts. Finally, the ENSI research programme

contributes to international projects

which Switzerland would be unable to conduct on

its own. International exchange of expertise, so

crucial to nuclear safety, is thereby encouraged.

The ENSI programme «Research into Regulatory

Safety» is divided into seven main areas:

1. Fuels and materials: this research covers the

reactor core and the graded approach to safety

barriers used for the confinement of radioactive

materials. The research into fuel is examining

primarily higher burn ups and safety criteria

for accidents. In 2012, the Halden Reactor Project

and the Studsvik Cladding Integrity Project

had a direct impact on the regulatory activities

of ENSI: Based on test results from accidents involving

a loss of coolant ENSI instructed the operators

of Swiss nuclear power plants to review

whether they were relevant to their own facilities.

In addition, ageing mechanisms affecting

structural materials are crucial to the long-term

operation of existing nuclear power plants. In

2012, the Fracture Mechanics Project was successfully

completed, contributing significantly

to the new ENSI-B01 Guideline on the monitoring

of ageing processes.

2. The OECD Projects on internal events and

damage encourage the international exchange

of experience on accidents and the

component damage that can trigger accidents

or have a detrimental effect. For this purpose,

specialised thematic databases are being created,

e.g. on damage to passive metal components

and on fire damage. These databases will

facilitate a systematic analysis of relevant operating

experience from numerous countries.

The new project CADAK is looking at the lifespan

of classified electrical cables. Long-established

databases are increasingly being used

for the purpose of systematic analyses. For example

in 2012, it was possible to issue overview

reports on high-energy arcs (FIRE Project)

and component reports on centrifugal pumps

and control rod drives (ICDE Project).

3. In addition to damage that may result from

events within nuclear power plants, the safety

analyses also reflect external events. In this

area, ENSI supports primarily international projects

conducting complex experiments and

simulations of aircraft accidents and earthquakes.

Finally, it is involved in some projects

that are especially tailored to conditions in

Switzerland such as the work by the expert

group from the Swiss Seismological Service

(SED) and PLATEX, the new Extreme Events

Platform involving several Swiss Federal authorities.

PLATEX will initially look at issues relating

to flood risks.

4. The effect of operator behaviour on accidents

in nuclear power plants is the focus point of research

into human factors. This relates on the

one hand, to the dependability of operator behaviour

under various conditions. In 2012, a

third nuclear plant in Switzerland was subject

to the methodology developed by the Paul

Scherrer Institute (PSI) in the Human Reliability

Research Project, which identifies and analyses

certain operator errors influencing negatively

the course of an accident. Thus specific proposals

to improve accident procedures were developed.

On the other hand, this research area

also focuses on the influence of the control

room layout on the performance of operating

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ENSI Erfahrungs- und Forschungsbericht 2012

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