Will a plant-specific full-scope simulator be available for Krsko nuclear power plant operators according to the schedule?

Yes, simulator building is under construction, at the supplier the acceptance tests of the simulator are in progress.

Are there working groups installed in the NPPs or within the operating organisation to deal with Human Factor aspects?

Yes, at NPP Krsko the Independent Safety Engineering Group (ISEG) deals with Human Factor aspects in accordance with Operating Experience Assessment Programme. ISEG is responsible for maintaining surveillance of unit activities to provide independent verification that these activities are performed correctly and that human errors are reduced as much as practical.

Man-machine interface improvement is basically achieved according to US standards, supplemented by recent studies such as PSA and experience feedback. The level of automation is not indicated : is there a rule in this field?

There is no specific rule in this field. However NPP Krsko, in accordance with USA standards and experience, developed the set of plant specific procedures for manageable and automated review of man-machine interface including Root Cause Analysis, Post-trip Review, Operating Experience Assessment Programme or/and Deviation Reporting. From the PRA (on power) point of view, NPP Krsko applied THERP Human Reliability Analysis (Technique for Human Error Rate Prediction) that also takes into account the man-machine interface.

Shutdown situations have particular features concerning human factors : are there specific measures (procedures) relating to shutdown situations?

Using the EPRI-s ORAM method the Shutdown PSA was performed. Based on that procedures were developed for refuelling and maintenance activities planning aiming at better controlling the risk and at avoiding the high-risk configurations. Recently, plant introduced the computer code based on ORAM approach which more effectively supports the risk management in shutdown states.

What are the criteria applied by SNSA to assess the safety culture level of licensee?

There are no established criteria in this field. The suggestion and recommendation of IAEA missions in this field are reasonably implemented and /or followed. IAEA documents in this field are used as a basis for safety culture implementation and evaluations.

Are there in Slovenia any R & D activities in the field of human factors related to nuclear safety? If so, what have been the main findings?

There is only limited financial support for R & D activities in the field of human factors related to nuclear safety.

Slovenian institutes have participated in IAEA programme (IAEA-J4-RC589) with the reports on:

• Methods for analysis of human impact on systems performance and safety

• Mathematical modelling of system performance in relation with selected human performances

An analysis of working places in the NPP Krsko was performed. As a result selection and follow-up criteria for important jobs were defined for general adaptation and accomodation, perception, reaction, personal integrity and stress resistance. 

A research on actual availability, potential availability and performance of operators in the control room of the NPP Krsko resulted in the preparation of curves of availability and performance for day and night shifs. Special mathematical model connecting human performance with the reliability was developed. On the basis of the results organisational changes were suggested. The finding was also that the work complexity in the morning shift should be decreased.

Recently special QA procedure for assuring long-term human availability and fitness for duty for permanent contractor performing construction activities was validated. Effectiveness of the procedure was evaluated by the results of periodical medical and psychological tests and field measurements and by estimation of worker performance.

Which major modifications have been made to the man-machine interface as compared to the original design?

The most important implemented modification directly related to the man-machine interface (MMI) is installation of Process Information System (PIS). In addition to a PIS project a lot of other implemented modifications affected consequently original MMI (see bellow).

Process Information System (PIS) Modification

The largest modification affecting MMI in the Main Control Room (MCR) was installation of PIS which incorporate twelve desktop monitors and four Main Control Boards (MCB) panel mount monitors, screen MMI for monitoring of Process variables, application programmes (Nuclear, Secondary etc.), System parameters trends with history, status of equipment etc. PIS System is using full graphic colour images, user friendly menu and soft-key driven display hierarchy, consistent colouring scheme, dynamic symbols driven by process signals, capabilities to exchange alphanumerical input/output messages with operators, functional - single touch action keyboards, etc.). 

During the preparation of this modification all related requirements issued by US NRC (see bellow) were respected.

Modifications or activities which have consequently changed also man-machine interface in NPP Krsko were:

• Review and correction of labelling or unambiguous identification of all components instruments and controls which are available in the MCR and in the field. 

• Annunciators were modified to implement annunciator free environment.

• Some local control panels were modified with reference to the signal and controls grouping, labelling, and panel colouring scheme.

• Upgrade of MCR environment factor engineering and environment (furniture, carpeting, colouring scheme for the panels and cabinets, air conditioning, and lighting).

• Most trend recorders were changed with the upgraded, which incorporate digital display.

• During the last years several new additional Radiation Monitoring Systems, using new digital display, were installed in MCB. 

During the Outage 1999 installation of Reactor Vessel Level Instrumentation and Inadequate Core Cooling Monitoring System will be implemented. Old Subcooling monitor will be removed and replaced with two (two trains) new analogue indications. In addition indications for Rx vessel level and Tauc high Thermocouple/per train will be added on the MCB. Original incore cabinet will be removed by new designed by Westinghouse (WDPF) equipped with two WESE station for monitoring of Thermocouples and other parameters.

US NRC documents which affected MMI upgrade related modifications in NPP Krsko were:

• NRC NUREG-737, Supl. 1, Clarifications of TMI Action Plan Requirements

• NRC NUREG-700, Guidelines for Control Room Design Reviews

• NRC NUREG-835, Human factors Acceptance Criteria for SPDS

• US RG 1.47, Bypassed and Inoperable Status Indication for Nuclear Power Plant Safety Systems

Does a plant policy on safety culture exist as a written document?

If yes, are managers and workers familiar with it?

Yes, plant policy on safety culture is referenced in a number of top tier documents with a clear statement of NPP Krsko policy on safety, production and responsibilities. This policy is defined in various documents like: Quality Assurance Plan, Plant Management Manual, NPP Krsko Policies and Goals, Company General Employee Training Handbook, Operating Experience Assessment Programme etc. Within these documents, clear statements are made about the policy on safety culture and developed into goals and objectives for each division within NPP Krsko.