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August 12, 1993

V.N. Shcherbin, Ukrainian Academy of Sciences, 'Concerning the Situation at the 4th Unit'

This document was made possible with support from Carnegie Corporation of New York (CCNY)

[bilingual Russian-Ukrainian letterhead of the Ukrainian Academy of Sciences' Interdepartmental Scientific and Technical Center]

"Ukrytie [Cover]"

[to] V. N. Vasil'chenko, the acting Director General of the PO [Production Association] ChAEhS


Translator's note: Although "ukrytie" means "cover" it refers to what is usually called the "sarcophagus"


12 August 1993 Nº 1109/638

in reply to Nº 60-3075 of 30 July 1993


[concerning the situation at the 4th unit]


In our opinion, the main reasons for the unfavorable situation which has developed are the high humidity of the atmospheric air and the disruption of the process of natural ventilation of the facility's premises.


As a result of a slowing of the movement of atmospheric air inside the facility it is deeply cooled and the dewpoint is reached long before the air leaves the facility. This leads to a condensation of atmospheric moisture on all surfaces, including the surface of TSM [possibly toplivosoderzhashchie materialy] "fuel-containing materials"] and the surfaces of load-bearing structures. In the process a danger of their volumetric humidification actually arises.


The heightened quantity of atmospheric precipitation is increasing this year, but it is not a determining factor of this process. The danger from such humidification of TSM and structural materials has a multi-faceted nature. This might lead:


- to a reduction of the subcriticality of the TSM and any other accumulations of nuclear fuel;


- to a washing-away of neutron-absorbing additives from places where nuclear fuel is concentrated;


- to an uncontrolled shifting and an accumulation of fissionable materials in unknown places (the concentration of uranium and transuranic elements in the waters of the Ukrytie facility quadrupled during this period and reached 15 milligrams/liter for uranium);


- to an increase of a mechanical destruction of the TSM and structural materials due to their freezing during winter;


- toward an increase of the leaching [vynos] of radioactive substances into groundwater;


- toward the system monitoring equipment and the Ukrytie facility technological safety support systems going out of commission, especially the electrical equipment (the latter circumstance increases the danger of a conflagration inside the facility).


[faded Ukrainian-language stamp

dated 12 August 199[[3]]


The danger increases of a worsening of the radiation situation in the premises of the Ukrytie facility as a consequence of an uncontrolled formation of a new sources of gamma-, beta-, and alpha-rays and a growth of a concentration radioactive aerosolsin the air of the industrial spaces. [Three question marks were handwritten to the right of the underlined portion]


In order to avert a further worsening of the safety condition of the Ukrytie facility it is necessary for the urgent adoption of the following measures:


- an operating organization according to a program coordinated with the oversight bodies and organization of a science director, putting all ventilation and heating systems of the facility to work in order to avert the condensation of moisture and the production of the humidity drying of TSM and structural materials,


- put in operation an installation to clean the water of the facility of uranium, plutonium, and fission product (initially, mobile, subsequently - fixed),


- under the supervision of Ukraine Goskomatom [the State Atomic Committee of Ukraine] a commission [komissionno - SIC] [should] investigate the reasons for the unfavorable situation which has developed at the Ukrytie facility with the working out of the necessary measures to improve it,


- put into the practice of work of holding joint operating conferences about the Ukrytie facility no less than once every two weeks under the supervision of the Director General (chief engineer) of PO ChAEhS and the Director General (Deputy Director General for Science) of MNTTs [the Interdepartmental Scientific and Technical Center] Ukrytie.


Deputy Director General [signature]   V. N. Shcherbin


Shcherbina 5-19-01

SI-5 12 August 1993


An outline of the reasons for the deterioration of the 4th block, largely owing to ventilation problems causing condensation to form, which freezes during winter and causes decay that can lead to the washing of nuclear particles into the surrounding atmosphere/groundwater. The report also proposes several emergency measures, such as improving ventilation systems, cleaning water from the block, and setting up of an investigation.


Document Information


Archive of the Ukrainian National Chornobyl Museum. Contributed by Anna Korolevska and Adam Higginbotham. Originally obtained from the Archive of the Chernobyl Nuclear Power Plant. Translated by Gary Goldberg.


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