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Unit one of the nuclear power plant Isar: the main control room
Source: E.ON Kernkraft GmbH, Kernkraftwerk
Isar (For a larger view, please click on the picture)
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The safety instrumentation and control (I&C) automatically controls and limits safety parameter
values like pressures, temperatures, liquid levels, and neutron flux
densities. In addition, I&C demands safety functions like power
limitation, turbine trip or even reactor trip if the given limits are
exceeded. In the time of plant construction hardwired I&C equipment
was installed based on analogue technology. Today the maintenance and,
if necessary, the redesign of such an equipment require a significant
effort. Thus, the analogue I&C equipment is being replaced with
software-based equipment also in German nuclear power plants beginning
with equipment of lower grade safety significance.
BfS is supporting BMU in setting up the regulatory framework regarding
the requirements on safety related applications of software-based
instrumentation and control (I&C) equipment in nuclear power
plants, in developing methods for demonstrating compliance with the
requirements and in the preparation of federal positions on licensing
issues, especially for I&C functions with high safety importance –
for example the reactor protection system. BfS is initiating and
controlling associated research projects and participates in meetings
of national and international working groups and contributes to their
discussions and progress.
Guidelines, rules and standards
According to the German Atomic Energy Act a license is required for the
application of software-based I&C for safety functions. An
associated regulatory framework is being developed, which particularly
comprises requirements on hardware and software qualification.
International Atomic Energy Agency (IAEA), European Commission (EC),
German Reactor Safety Commission (RSK) have published their
guidelines, and International Electrotechnical Commission (IEC), German
Nuclear Standard Committee (KTA) have issued related standards and
rules. Based on these advanced national and international requirements
a comprehensive framework for the safety demonstration of
software-based I&C is being developed in Germany with BfS
involvement.
Results of international working groups
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Report "Licensing of safety critical software for nuclear reactors"
(For reading the report, please click on the picture)
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A recent example is the report „Licensing of safety critical software
for nuclear reactors. Common positions of seven European nuclear
regulators and authorised technical support organisations. Revision
2010”. This document describes the work of a group of regulator and
safety authorities’ I&C experts from AVN (Belgium), BfS (Germany),
CSN (Spain), ISTec (Germany), NII (United Kingdom), SSM (Sweden), and
STUK (Finland).
The report provides common technical positions on a set of important licensing
issues raised by the design and operation of safety critical software
used in Nuclear Power Plants for the implementation of safety
functions. A revision of the common position and recommended practices
of the European Commission consensus document published in May 2000: “Common position of
nuclear regulators for the licensing of safety critical software for
nuclear reactors (EUR 19265)” is part of this report. Complementary the new report version contains a statement concerning the qualification of software-based field equipment installed outside the central I&C system, like sensors and actuators.
Licensing
of safety critical software for nuclear reactors. Common positions of
seven European nuclear regulators and authorised technical support
organisations Revision 2010 (pdf, 763 kB, not barrier-free)
You can find the at the BfS-Online Repository ("DORIS"). Please always refer to urn:nbn:de:0221-201101244617 as source when quoting.
Research projects concerning software based instrumentation and control important to safety:
Reliability assessment for
software based instrumentation and control important to safety as well
as safety demonstration issues concerning the application of this
technology to nuclear facilities
Based on available operating experience (also covering maintenance) and
upgrading experience of instrumentation and control (I&C) in German
nuclear power plants, the associated requirements of the safety case to
apply software based I&C important to safety in nuclear power
plants are identified and assessed. International information exchange
was taken into account. The listed reports deal with selected
aspects of the reliability analysis.
(German version; English version not available)
- Zusammenstellung von Anforderungen an die Aufzeichnung und Bewertung von Betriebserfahrungen mit rechnergestützter Leittechnik sowie Bewertung von Möglichkeiten zur Ableitung von Zuverlässigkeitsaussagen
Institut für Sicherheitstechnologie, Garching, Mai 2003 (pdf, 1 MB, not barrier-free)
- Anforderungen an Prüfung und Überwachung rechnergestützter Einrichtungen mit Sicherheitsbedeutung während der Inbetriebsetzung und des Betriebes
Institut für Sicherheitstechnologie, Garching, Mai 2003 (pdf, 1 MB, not barrier-free)
- Anforderungen an die Instandhaltung und Modifikation von rechnergestützten Komponenten und Teilsystemen der Sicherheitsleittechnik
Institut für Sicherheitstechnologie, Garching, April 2006 (pdf, 414 kB, not barrier-free)
Compilation of the safety
requirements on interfaces of the peripheral equipment for measurement
and actuation connected to software based instrumentation and control
systems important to safety in nuclear power plants
Modern I&C systems build on bus systems for data communication.
For safety reasons appropriate interfaces are required to connect the
peripheral and central I&C equipment whereby the data communication
and processing equipment shall meet a consistent set of requirements.
By means of two representative bus types the safety properties were
investigated and essessed.
(German version; English version not available)
Safety demonstration for computer-based I&C with components off the shelf for application in NPPs
A structured safety demonstration procedure for software-based I&C is proposed including a systematic link to the detailed I&C specific regulatory framework. Within this systematic the DIN IEC norms are considered particularly – these are international IEC standards endorsed for the application in Germany. The systematic makes also visible the complexity of distinct demonstration objectives. Consequently it may contribute to identify and evaluate uncertainties in applying the requirements.
(German version; English version not available)
- Verfahrensweise zur Anwendung der "Sicherheitsanforderungen für Kernkraftwerke - Software-basierte Leittechnik mit sicherheitstechnischer Bedeutung (Modul 5, Rev. C)"
Institut für Sicherheitstechnologie Garching, ISTec – A – 1018, Juni 2009 (pdf, 453 kB, not barrier-free) - Verfahrensweisen zur Erfüllung der "Sicherheitsanforderungen für Kernkraftwerke: Softwarebasierte Leittechnik mit sicherheitstechnischer Bedeutung"
Ergänzender Bericht zu ISTec - A – 1018, Institut für Sicherheitstechnologie Garching, ISTec – A – 1357, Juni 2009 (pdf, 501 kB, not barrier-free)
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