All Chornobyl NPP facilities in the exclusion zone remain under the aggressor’s control.

On 9 March 2022 at 11:22, the last power supply line on the site was lost. There is no possibility to communicate with personnel directly on site. Regulatory control over nuclear and radiation safety at the Chornobyl site and in the exclusion zone, as well as control of nuclear materials at the ChNPP, has been completely lost.

Restoration of electricity supply and, accordingly, communication with the operational personnel of the Chornobyl NPP are not currently possible because of hostilities in the area where high-voltage lines are damaged.

Prior to the loss of communication, all spent nuclear fuel of the Chornobyl NPP was stored in two interim spent fuel storage facilities (ISFs):

• ISF-1 (wet storage facility)
• ISF-2 (dry cask storage facility).

There is no nuclear fuel at Chornobyl NPP Units 1, 2, 3.

Scheduled transport of spent fuel from ISF-1 to ISF-2 was suspended before the Russian troops captured the site.

The actual situation on the site is currently unknown.

According to the information available to SNRIU after loss of power, the emergency diesel generators have been turned on to supply power to systems important to safety of the facilities, including ISF-1, ISF-2 and New Safe Confinement over the Shelter (Shelter NSC).

In case of failure-free operation, the amount of diesel fuel for diesel generators will be sufficient for 48 hours since the instant the external power is lost.

Potential threats at the Chornobyl NPP facilities in case of loss of emergency power supply

ISF -1 

As of 10 March 2022, 19,442 spent fuel assemblies are placed at ISF-1. The decay heat is removed from the nuclear fuel by circulation of the coolant (water) in the cooling pool. This function requires power supply.

In case of total blackout, including loss of emergency power supply, ISF-1 personnel will lose the possibility  of:

• remote monitoring of the radiological situation in the storage facility rooms;
• remote control of the water level and temperature in the cooling pool;
• makeup of the cooling pool and its water treatment;
• fire alarm monitoring;
• maintenance of required temperature in ISF-1 rooms.

When water temperature in the cooling pool reaches 40 °С because of intensive evaporation, this will lead to conditions in which instrumentation may fail and it will be very complicated for the personnel to take measures to control potential emergencies and accidents. The radiological situation at ISF-1 will also significantly deteriorate and the personnel will be subjected to additional doses.

Also, according to the design, if the ventilation system becomes inoperable and compensatory measures cannot be taken, explosive concentrations of hydrogen may be generated through radiolysis.

ISF -2

Spent nuclear fuel is stored at ISF-2 according to the passive principle.

In case of total blackout, including loss of emergency power supply, the ISF-2 personnel will lose the possibility of:

• remote monitoring of the radiological situation in the storage facility rooms and site;
• maintenance of required temperature in ISF-2 rooms;
• fire alarm monitoring.

Shelter NSC:

Total blackout of the Shelter NSC, including loss of emergency power, will cause:

loss of automated monitoring over the parameters that characterize nuclear and radiation safety and condition of unstable structures destroyed in the April 1986 accident at Unit 4;

inactivation of safety-significant ventilation systems and integrated control system;

inability to use safety-significant systems that are on standby in normal operation, such as the neutron absorber introduction system, liquid radioactive waste management system and fire protection system.

Therefore, long-term loss of power at the Chornobyl NPP, together with the limited capabilities of the operating personnel, who are now physically and psychologically exhausted because of the impossibility to change shift and the constant presence of armed occupants, will lead to loss of control over the safety parameters and inability to effectively respond to internal and external initiating events, such as fires if they occur, which in turn can lead to severe radiation effects.

In addition, after loss of emergency power supply, the ventilation and air conditioning systems will stop their operation in rooms of all radiologically hazardous facilities of the Chornobyl NPP; this will cause additional doses to personnel, including those during walkdowns and mitigation of potential accident consequences.

Radioactive contamination on the Chornobyl NPP site and in the exclusion zone will increase as well because the occupant fails to comply with radiation safety requirements and strict access control procedures.