Concreting proceeds at Baltic NPP

Changes to control and instrumentation (C&I) system architecture, including:
-Addition of a non computerised C&I safety back up system;
-Introduction of one way network communication from the protection system to lower classified systems; and
-Introduction of Class 1 displays and manual controls and indications in the main control room and remote shutdown station.

Additional reactor protection system trip signals, such as:
-A high neutron flux trip
-A high axial offset trip
-A hot leg high pressure trip
-A reactor coolant pump low speed trip.

Automation of certain actions such as:
- Activation of the emergency boration system in the event of a steam line break;
- Isolation of pipework in the event of leaks to prevent flooding; and
- Actuation of the emergency feedwater system on detection of low steam generator pressure.

Improvements to the spent fuel cooling pond, including:
- Removal of several penetrations and openings in the spent fuel pool to increase the robustness of the structure
- Installation of protection (such as penetration covers, secondary containments etc) to prevent leaks from spent fuel pond penetrations;
- Improvements to the cooling water supply systems to the spent fuel cooling pond; and Changes to SFP fuel handling procedures.

Upgrade of the safety classification of numerous structures, systems and components (SSCs) that are important to safety including:
-Parts of the C&I systems;
-The primary circuit safety injection accumulators;
-The Ultimate Diesel Generators (UDG);
-The electrical earth system;
-The actuation signals for:
- Starting the UDGs;
-Starting the Primary Depressurisation System (PDS);
-Closing the diverse full load Main Feedwater Isolation Valves;
-Actuation of the Emergency Boration System (EBS).

Other modifications that provide additional diversity, defence in depth, or other safety improvements such as
-Provision of additional diversification in the electrical power supplies to key components to reduce the probability of common cause failure;
-Modification of the primary circuit pipework to facilitate through life inspection; Strengthening part of the civil structure to improve protection against potential
dropped loads near the reactor primary circuit;
-Upgrading the heating and ventilation support systems which play an important role in cooling essential safety systems such as C&I;
-Providing a diverse heating and ventilation system;
-Upgrading the control systems for the main and diverse heating and ventilation
systems;
-Improvements to the system for detecting small steam generator tube leaks; and
-Reassessment of the irradiation embrittlement surveillance scheme to take account of the effects of the heavy reflector inside the UK EPR reactor pressure vessel.

Post-Fukushima reviews:
Directly as a result of the Fukushima lessons learnt review, EDF and AREVA identified five design change proposals, covering 16 resilience enhancements, that include the following:
-Improved flood protection for emergency electrical supplies (both AC and DC); -Extension of the capability and autonomy of emergency electrical supplies (both AC
and DC);
-Identified connection points for proposed mobile diesel generators;
-Addition of SFP instrumentation into the severe accident management C&I systems;
-Identification of a reserve ultimate water supply: and
-Delivery of water via mobile pumps for SFP make up and containment pressure control.