02.05.2020

Chernobyl Robots (Part-3)

Special transport robot - 1


During the liquidation of the accident at the Chernobyl nuclear power plant with the help of robots, about 15,000 m2 of various premises of the station, roofs of buildings and the territory of the Chernobyl NPP were examined. Also, thanks to robots, about 5000 m2 of the station itself was cleaned. Service robots was assigned to the operators of the Central Research Institute of the RTK (Central Research Institute of Robotics and Cybernetics). Robotics carried out work on the territory of the Chernobyl NPP from June 1986 to February 1987. After that, all the robots that remained in the work were transferred to the leadership of the Chernobyl NPP, and for their operation there were several employees of the Central Scientific Research Institute of the RTK who transferred to the special service created for these works.
In the third part of the “Chernobyl robots” we will tell you about the same moon rover that performed work on cleaning the Chernobyl roof. Specialized Transport Robot STR-1. The lunar rover was developed in less than 4 months and was already put into operation at the station on September 1, 1986.


Why, after all, a lunar rover? STR-1 owes its history to a team of engineers led by Kemurdzhian Alexander Leonovich. At the beginning of the 70s, the team created devices for studying the surface of the moon - Lunokhod-1, in 1970, and Lunokhod-2 in 1973. In fact, the complex was created in a very short time by the efforts of dozens of organizations and enterprises, a complete list of which is not possible in a short form. The main participants in the cooperation were three enterprises.
- VNII NPP, Moscow (director ZA Aganbegyan) - data on the architecture of the buildings of the third block, the operating conditions of equipment on its roofs, the development and manufacture of the working body - a dozer blade with a lifting-lowering mechanism.
- IFTP, Moscow (director L.N. Lupichev) - development and creation of a television and radio complex, organization of work on a contractual basis.
- VNIITRANSMASH, Leningrad (director P.P. Isakov) - the general ideology of the complex, the creation and experimental development of the STR, transport cradle and technological equipment.

A great contribution to the creation of the complex was made by the Leningrad enterprises Proletarsky Zavod, NPO Istok, NPO Elektronmash, GOI, Television Research Institute and others. Traction electric motors were supplied by Pskov, television cameras - Novgorod, charger (charger) - Dnepropetrovsk. Specialists of the Kiev Institute of Automation participated in the creation and testing of the radio complex. Broad cooperation made it possible to create the whole complex, exclusively, on a domestic scientific and production base. When creating the STR, the scientific and technical backlog accumulated in VNIITRANSMASH in the process of carrying out R&D on planetary rovers was used. The timing of creation can be judged by the following chronology of events.

 

- May 12, 1986 - participation of the First Deputy Director of VNIITRANSMASH E.K. Potemkin and Deputy Director - Chief Designer A.L. Kemurdzhiana at a meeting of representatives of the military-industrial complex enterprises in Chernobyl, dedicated to the technical support of medical facilities.
- July 1986 - completion of the production of two samples of the STR self-propelled chassis, completion of the bench and running tests of the chassis, sending the STR to Moscow for complex tests at the VNII NPP with simulated working conditions on the roofs.
- August 8, 1986 - the arrival of specialists from VNIITRANSMASH, IFTP, VNII NPP and NPO Istochnik for practical work and delivery to Chernobyl of the equipment of the complex (the head of the 1st crew of the STR operation - PS Sologub).
- August 20, 1986 - landing of the STR complex on the roof of the central hall (CZ) and in the secure console rooms of the 3rd power unit.
- September 1, 1986 - the beginning of the work of the second crew for the operation of the STR (head of the brigade M.I. Malenkov).


When designing this robot for liquidation of the consequences of the Chernobyl accident, technical solutions for the design of the self-propelled chassis were selected based on the requirements of high throughput in the rubble, autonomy in power supply, stability when overcoming obstacles, reliability, high maneuverability, the ability to deactivate the chassis with chemical solutions and mechanical methods, resistance of selected materials and components to radioactive radiation and decontamination. As a result, the self-propelled chassis was a six-wheeled vehicle with individual wheel drives and brakes, an independent long-travel link suspension of each wheel and a longitudinal arrangement of elastic elements - titanium torsion bars. The wheels were made in the form of sealed rigid metal toroidal shells with lugs of various patterns for extreme and medium wheels. The autonomy of the STR was ensured by the use of two silver-zinc batteries. The absence of cable connections between the STR and stationary control and power supply equipment made it possible for the robot to turn confidently “in place” with a radius of zero — all this ensured the robot’s high maneuverability and greatly simplified the landing of the complex on the roof.
But, despite such a short time in the development of the robot, it was possible to implement the following fundamental approaches:


• designing a self-propelled chassis, first of all, a running gear and an individual electromechanical traction drive, especially for the conditions of operation of the STR on roofs;
• experimental verification of new technical solutions in the process of bench tests of assemblies and running tests of STR;
• Minimizing the number of operations in which people are involved.

In the construction of the STR, three components can be distinguished, which were worked out autonomously:


• self-propelled chassis with devices, blocks and devices that provide movement.
• airborne television and radio complex (RTK).
•    working body.


The first stage of practical operation is the delivery of the complex to the roof. Initially, the Libcher crane developed at NIKIMT was used to deliver the robot to the roof.
After a crane accident, MI-8 helicopters with external suspension were used to deliver and evacuate all equipment to and from the roof. But due to the fact that at the beginning of October 1986, the MI-8 helicopter crashed at the Chernobyl nuclear power plant, resulting in human casualties, helicopter flights over the station were prohibited. At the same time, the number of operations that could be performed only by humans increased - designation of a place for landing robots, slinging of an automatic lock of an external suspension, docking and undocking of cables from a charger to a transport cradle. Transport overloads also increased. However, during all these operations, there were no state of emergency or STP failures during or after transportation.
During operation, the robots cleared the debris and decontaminated, conducted radiation reconnaissance and visual inspection of the territories using on-board cameras on the roof of the central hall (zone K), at the site near the ventilation pipe (zone M), at elevations of 70.93 m (zone L) and 50.02 m (zones B and C). All these zones have some common elements, namely metal perimeter fences installed on concrete beams, fire pipelines laid along the perimeter at a height of 0.5 m, lightning protection buses.
The nature of blockages on all roofs was determined by the heterogeneity of the materials that made it up and the high temperatures associated with the explosion and fire. As a result, the roofing-bitumen layers of the roof melted, which incorporated fragments of graphite masonry, fragments of fuel cartridges and other metal and concrete fragments of structures. As a result, such conditions hindered the movement in the rubble. Nevertheless, both samples of the STR never stopped moving due to loss of patency.


The radiation situation in various zones was radically different and significantly changed during the work. The maximum exposure dose rate (EDR) of x-ray and gamma radiation in zone B, which was completely cleared with the help of STR, was 2800–3100 x-rays per hour. At the site near the pipe (zone M), devices with a dose scale of up to 10,000 x-rays per hour went off the scale. Up to 70% of EDRs produced hard gamma radiation with an energy of 3.3 MeV. No STP failures due to radioactive radiation were observed.
But in general, failures in the operation of the STR on the roof, of course, were. Most of them accounted for the radio and television complex, which, as noted, was assembled on the basis of serial components that are unprotected from exposure to radiation. On the self-propelled chassis, there was, in fact, only one serious failure. As a result of the start-stop mode of movement and thermal overloads, the windings were disconnected from the brushes of the collector of the electric motor of one motor wheel. Specialists of the operation crews eliminated all failures on their own, without involving military personnel. According to the LPA headquarters at the Chernobyl nuclear power plant, the bare costs for servicing the STR-1 complex were minimal and related only to regular operations listed above.


According to the headquarters for medical facilities at the Chernobyl nuclear power plant, the use of the robotic complex STR-1 allowed us to exclude the involvement of more than 1000 people in work in hazardous areas. Thanks to the moon rover in zone B, more than 90 tons of radioactive materials were removed from the roofs, which reduced the DER by two orders of magnitude. Maintaining people's health - this was the main result of the operation of the STR-1 robotic complex.

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