Archive for January, 2017

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Chernobyl Unit 4, November 2016

January 19, 2017

Please select any photo in the galleries for a larger version and descriptive caption.
In November 2016, the massive New Safe Confinement arch slid over Unit 4 of the Chernobyl Nuclear Power Plant, and the old “Sarcophagus” that had defined the appearance of the damaged unit for 30 years receded from view.  Over the last three years, the iconic ventilation chimney shared by Units 3 and 4 has been disassembled as well, and now rests in pieces in various places (including the deck of No. 5 turbogenerator).  Inside the unit, work continues to finish the Perimeter Closure Project–the effort to hermetically seal off the east and west boundaries of the New Safe Confinement from the rest of the power plant.  Floor by floor, barriers are going up.  The memorial to Valery Khodemchuk, the first victim of the 1986 accident whose remains have never been recovered, has been removed from its old location at the northwest end of the chemical treatment and ventilation block, and will be reinstalled somewhere else once the project is finished.  The photos in the second gallery show the state of the Arch and the Local Zone around Unit 4 only several days before the Arch began its movement, and are certainly among the last photos of the old Unit 4 exterior we have come to know and love.

I was honored to have Bionerd along for this trip, and her video record of the visit inside Unit 4 is on YouTube here:

Finally, here is a gallery showing the Arch of the New Safe Confinement and some of the “Local Zone” surrounding Unit 4.

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Chernobyl Unit 2, November 2016 (Part 2)

January 18, 2017

Please select any photo in the galleries for a larger version and descriptive caption.

The reactor hall and control room of Unit 2 at the Chernobyl Nuclear Power Plant are documented in these photo galleries and companion video.

Room 612/2 (Central Hall); Room 804/2 (Refueling Machine Control Room)

The RBMK reactor design features an ability for online refueling: withdrawal and insertion of fuel bundles while the reactor is at power.  The charge face with its 2000-some channel covers is sited above the reactor within a massive “central hall” that is built like a hot cell, with concrete entryway mazes and leaded-glass windows for refueling operators.  The dominant piece of equipment is, of course, the crane-mounted RZM (refueling machine).  Also in the central hall are two spent-fuel basins, fresh fuel and instrumentation storage hangers, and metal plate covers for accessing the upper steamwater pipelines from the reactor and the peripheral ionization chambers.  Unit 1 and 2’s central halls are on the +20.2m elevation, typical of first-generation RBMK plants, while the later Unit 3 and 4 central halls are on +35.5m.  The chief reason for this is the introduction of a steam-suppressing pool and “Accident Localization System” below the reactor in the later design.  Unit 2 has been offline since a turbine hall fire in 1991, and is defueled and dry (all spent fuel is in the ISF-1 facility).  The spent fuel pools in the reactor hall are also dry, but are currently being used to store fuel support stringers.  Measured exposure rates in the reactor hall range from surprisingly low (3 mR/h on uncovered fuel channels on the “pyatak” or reactor lid) to surprisingly high (2 R/h close to a point source-maybe a fuel flea?-on a fuel stringer).  Like other RBMK reactors, including Unit 3 at Chernobyl, ChNPP-2 participated in transmutation doping of silicon for the Soviet semiconductor industry.  A single channel ordinarily used for the control and protection system was assigned for this application.

Video (via YouTube)

Room G364/2 (Unit 2 Control Room)

The control room, like all others at RBMK plants, is situated nominally at +10m elevation in the “deaerator stack” abutting the turbine hall.  The tray-type deaerators themselves, and reactor steam and feedwater piping, are in compartments directly above the control rooms, leading to some interesting hypothetical accident scenarios whereby radioactive water might invade the control rooms from above.  At ChNPP, the Unit 2 control room has a notable radiation “hot spot” above T Desk at the west end, possibly due to contamination in the steamwater piping compartment upstairs.

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Chernobyl Unit 2, November 2016 (Part I)

January 17, 2017

Please select any photo in the gallery for a larger version and descriptive caption.

This photo gallery documents the main circulation pumps and the repair/transport corridor in Unit 2 at the Chernobyl Nuclear Power Plant as they appeared in mid-November 2016.  Unit 2 operated until a fire damaged the No. 4 generator and the unit’s feedwater machinery in October of 1991, after which the unit was permanently shut down.  It is an example of the earliest variant of the RBMK plant design, following the model of the Leningrad units.  The main circulation pumps in these earlier units are aligned on an axis perpendicular to the turbines and on the +1.0m elevation, whereas in the later generation of RBMK units (e.g. ChNPP Units 3-4), the pump engines are on the +12.5m elevation and aligned parallel with the turbines so that twinned units could share the same MCP engine halls and associated cranes.  The earlier-generation units are smaller than the later generation, mainly because they lack a steam-condensing “accident localization system” beneath the reactor.

Locations shown in the photo gallery may be identified on the following plan of the +1m elevation in the Unit 2 reactor building, taken from plant safety documentation:

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