5.3.2 Operation limits and conditions

It was already the former ČSKAE that required limits and conditions for operation (L&C) as part of the safety report. L&C are in place for all nuclear installations in the Slovak Republic, whose format and content follow IAEA and US NRC guidelines. Every limiting condition containes:

• Objective,
• Wording,
• Validity (to what mode of the nuclear installation it applies),
• Activities of the operating staff upon the limit conditions being not met,
• Requirements on control - set the frequency, type and extent of controls and tests of systems and equipment.

L&C were issued for NPP Bohunice V-1 units prior to their commissioning in 1978, they had been reviewed by a variety of research institutions, including VÚJE. L&C for WWER-440/230 units were issued in mid-1980s, revised according to the IAEA guide (SG - O3) with using the format of Westinghouse and US NRC guidelines for PWR units. Having been approved by the regulator, they came into force in 1988.

L&C for NPP Bohunice V-1 unit operation were amended in 1995 to make three separate documents (their content and form following IAEA and US NRC guides):

• Limits and conditions for the operation of NPP Bohunice V-1 unit 1,
• Limits and conditions for the operation of NPP Bohunice V-1 unit 2,
• Limits and conditions for the operation of the interim spent fuel storage facility

L&C was amended in January 2001 that became part of the Safety Report After Gradual Upgrading. The documents were submitted to ÚJD for review.


L&C for NPP Bohunice V-2 units were developed according to IAEA guide (50 - SG - O3) and US NRC guide (for PWR units) as soon as the nuclear installation was commissioned. In March 1998, amended L&C were issued, being split into two separate documents:

• Limits and conditions for the operation of NPP V-2 unit 3,
• Limits and conditions for the operation of NPP V-2 unit 4.

The amended L&C were reviewed by the regulator and approved according to the regulations during 1998 and 1999.

Limits and conditions of safe operation of NPP Mochovce were developed and reviewed within the Pre-operation Safety Report. ÚJD approved the draft L&C in April 1998. L&C follow IAEA and US NRC guidelines. Their formal structure is the same as L&C for the operation of NPP Bohunice units, with limit conditions added, based on specific design of NPP Mochovce. The document was amended in 1999 and 2000, being split into two separate documents:

• Limits and conditions of safe operation of NPP Mochovce unit 1,
• Limits and conditions of safe operation of NPP Mochovce unit 2

Limits and conditions of the operation of the interim spent fuel storage facility (ISFSF) were developed in accordance with the Safety Report. Since the early days of the deposition of spent fuel until 1995, L&C used to be organizational part of L&C for the operation of NPP V-1 units. In January 1998, L&C were amended by the operator, they were reviewed by ÚJD and approved in July 1998 for the period of the ISFSF upgrading until January 2000. Following the completed upgrading, new L&C were developed as part of the Safety Report After the Upgrading. L&C were developed in accordance with IAEA and US NRC guidelines, reviewed by ÚJD and approved in January 2000.

Limits and conditions for the operation of the National Repository of RAW (RÚ RAW) were developed as part of the Safety Report. Formally, their structure follows IAEA and US NRC guidelines. They were reviewed by ÚJD and approved in July 1999.

Limits and conditions for the operation of the Bohunice RAW Processing Center were developed as part of the Safety Report, based on IAEA and US NRC guidelines. L&C are linked to limits and conditions for the operation of RÚ RAW. Formally, they have been drafted in accordance with L&C for all other the other nuclear installations in the Slovak Republic. L&C were reviewed by ÚJD and approved in July 2000.

The adherence to limits and conditions is continuously monitored by the operating staff and, on a daily basis, by the staff of technical support.

Prior to setting the unit on a lower sequential number mode, the operating staff have to verify such transition based on checklists that are part of operating documents. The verification verifies whether all limits and conditions applicable to the transition mode are met. Shift engineer does not approve such a transition unless the meeting of all L&C has been verified .

The responsibilities of individual employees and/or divisions of operator to notify regulatory bodies of the occurrence of a „L&C Violated“ situation is laid down in also the quality assurance directive „Management of Events at Nuclear Installations“ that basically contains three levels of notification:

• The regulatory body must be notified by phone within 8 hours; responsible is the shift engineer on duty;
• operator has to send the regulatory body, within 72 hours, a preliminary report on the event;
• within 30 days, operator has to present a report on L&C violation, along with an analysis reviewed by the Failure Commission.

If there is a need to amend L&C, an annex to the regulation is drafted with the corresponding reasoning, and such a change becomes effective upon being approved by the regulatory body.

Operator’s nuclear safety supervision departments draft periodical quarterly and annual reports on the status of nuclear safety; the reports are presented to the power plant management. As part of the reports, also the whole area of L&C is evaluated. The parameters include numbers of changes made in L&C, allowed draw dawn of the time during which limit conditions have not been met, duration of safety systems being not available, and L&C violation, if any.