Due to the news published in the media and wide public discussions of the potential risks of “an uncontrolled release of nuclear energy” from the fuel-containing materials located inside the Shelter after the NSC was put into the design position, we communicate the following.
Following installation of the NSC Arch into its design position over the Shelter, certain IAMS sensors were tracking increase of neutron activity in the accumulations of fuel-containing materials (FCM) located in room 305/2 in subreactor slab melting area. This situation had been predicted by the ISPNPP before the NSC Arch was slid over, and was taking place due to drying of overmoistened environment of black lava-like FCM (LFCM) layer which is located higher (at elev. +9.00 ÷ + 9.70) than potentially nuclear-hazardous FCM (NFCM). ISPNPP experts predict that the NFCM will be further constantly contributing to the neutron activity level registered by the IAMS sensors. The total neutron activity will continue to slightly rise due to decrease of water content in LFCM layer located above the NFCM, until an optimal ratio of water and fuel is achieved. Should the environment be further dried, the neutron flux density is predicted to be slightly decreased or there will be abnormally long period of constant values of neutron flux density.
On April 29, the OSCE representatives, namely Ambassador Henrik Villadsen, the OSCE Project Co-ordinator in Ukraine, and Deputy Chief Monitor of the OSCE Special Monitoring Mission Mark Etherington visited Chornobyl NPP with a technical tour.
On the 26th of April, as part of the events dedicated to the 35th anniversary of the accident, the former residents of Prypiat planted more than 200 rose bushes.