1989
Start of the second resettlement phase. About 100 000 people have to leave their villages in the severely contaminated territories of Belarus, Ukraine and Russia.
26 January: Politburo unexpectedly announced a new campaign (concentrated on Belarus) to cope with the consequences of the disaster.
February: The first maps highlighting radiation fallout from Chernobyl are published in the Soviet press.
23 February: First visit of Soviet president Michael Gorbatchov to Chernobyl. He spends one hour at the site.
May: Norway: According to the Isotope Lab of the Agricultural University of Norway, 95% of radioactive elements are still present in upper soil layers and weathering processes within the next few years may increase the uptake of the Chernobyl fallout in the food chain (major grazing areas for livestock and domestic reindeer have been particular affected).
23 May: Decision not to complete the two units under construction. Construction work on Block 5 & 6 resumed on Oct 10, 1986, and already halted on April 24 1987
26 October. Tass reports that during the following year 100,000 people will be evacuated from contaminated areas in Belarus.
 

1990
Collaboration between Western scientists and experts from Belarus, Ukraine and Russia begins. A delegation of German scientists visits the Chernobyl nuclear power station and the affected regions.
April: According to Yuri Shtcherbak, vice-chairman of the Supreme Soviet Commission on Environment & Nuclear Energy said some US320 billion will be needed to handle the consequences of Chernobyl in the next 10 years.
14 April: A serious case of radiophobia: In a dutch village a woman was found who lived wrapped in large amounts of plastics in a plastic tent inside the living-room since the accident. The woman lived in her parents house and had not leave the house since April 1986
26 April: a marathon broadcast of 24 hours to raise awareness and money for Chernobyl victims. On soviet national televison Telethon Chernobyl on Channel 3 collects about US$100 million.
19 August: IAEA claims the sarcophagus is due to high temperatures and radiation no longer reliable. A new catastrophe cannot be ruled out
September. Computer data stolen in Minsk and destroyed about health situation and radiation levels from over 670,000 people living in the eastern part of Belarus. Also contamination details from 20,000 settlements were on the disks.
21 September. The IAEA and the Governments of the Soviet Union, the Belarussian and Ukrainian SSR sign a framework agreement on the international consequences of the accident. “The Chernobyl area affords” according to the IAEA press release, “unique possibilities for carrying out scientific research under post-accident conditions, including some areas where radiation levels have subsides but are still above normal background levels.”