Chernobyl Nuclear Accident Congressional Hearings Transcript

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3.0 OPERATIONS PROJECT AREAS
Operations Project Area 3.1—Decommissioning Power Plant
This project area addresses all of the activities required for the decommissioning
of the operable reactors at the Chernobyl site. This will require the removal of fissionable
components of the units, removal and disposal of contaminated items, decontamination
to the extent possible of on-site facilities and equipment, and the
placement of all items in a safe configuration.
The sub-projects described below must, in general, be accomplished sequentially,
since the start of one may require the successful completion of the other.
Sub-projects
3.1.1 Prepare Written Decommissioning and Decontamination Plan
A plan and schedule for the decommissioning of the reactors will be prepared for
the review and approval by MinChernobyl. The plan will contain the standards to
be met by the decommissioning activities and the schedule will contain options for
delays in the decontamination should this appear desirable.
3.1.2 Interim Safety Measures
Safety measures to be in place during the decommissioning phase will be identified
and implemented. These will include, but not be limited to:
• Establishment of a site-wide monitoring and surveillance system;
• Provision of fire protection systems or supplement existing systems during decommissioning;
• Provision of additional ventilation to accommodate radioactivity which may be
released during decommissioning and decontamination;
• Review of structural and foundation capacity of long-term viability; and,
• Shutting off and sealing all passageways and openings not in use to restrict possible
release of radioactivity.
3.1.3 Decommission Reactors
In order to proceed with the decommissioning and decontamination of the three
operable reactors at the Chernobyl site, it is first required that they be placed in a
non-critical configuration, and that it be assured that they cannot be restarted. Initially,
this is achieved by the insertion of poison control elements, but modifications
to the control system and eventual removal of fuel is also required.
3.1.4 Reactor Cool-Down
Following reactor shutdown, it will be necessary to maintain coolant circulation
to remove the decay heat residual. The length of time this is required depends on
the fuel loading, fuel burn-up and recent operating history of the reactor. Cool-down
progress is monitored by temperatures in the reactor, but may vary within individual
fuel elements. For this reason, calculations of heat generation as well as measurements
will be employed.
3.1.5 Remove Fuel
Following the reactor cool-down period, removal of the fuel from the reactor
vessel can be accomplished. This operation will be completely remote and will be
accomplished with the existing fuel handling equipment. The fuel will then be
either placed in additional cooling or packaged for disposition. The decision will
depend on the fuel conditions at the time of cool-down and the facilities available to
receive the spent fuel.
3.1.6 Liquid Decontamination
With fuel removed from the reactor, decontamination of the coolant loops can proceed.
This will first require sampling for radioactive and other pollutants, then
treatment. Treatments may include filtration, precipitation, ion exchange or evaporation.
The goal is to dispose of the water completely, leaving only residues to be
disposed of as radioactive waste.
3.1.7 Cleanup and Dismantle Facility and Equipment
AVith the reactor facility empty of fuel and liquid, disassembly of equipment and
facilities can be accomplished. Detailed monitoring of each item will be required to
determine the proper safe procedure for decommissioning and the proper disposal
method. Material which can be decontaminated for reuse will be treated accordingly.
Equipment such as control room components and electrical generators will be
examined for possible reuse. Activities related to the cleanup of Unit 4 will be surveyed
for possible synergism.
3.1.8 Containment