Viacheslav Orlov. At the time of the accident, he worked as deputy operating manager of reactor shop No. 1 (RS-1) at ChNPP Stage I. Then he worked in the regulatory authorities of the USSR and Ukraine. Now retired.
Arkadii Uskov. At the moment of accident, he worked as a chief operating engineer of reactor shop No. 1 at ChNPP Stage 1. Currently, he holds the position of an adviser to the head of the State Agency on Exclusion Zone Management.
30 years have passed since one of the biggest global man-made accidents, which occurred at Chornobyl Nuclear Power Plant (ChNPP). It is still quite difficult to draw an accurate, true and complete picture of the events during the first hours and days of the accident even for those who were at the power plant that day.
The editorial board of Uatom.org (E.B.) has communicated with ChNPP accident liquidators, Viacheslav Orlov and Arkadii Uskov, to share personal memories, feelings, experience, emotions of witnesses and participants of the event with you.
“This is not just an accident at ChNPP, but a global scale catastrophe. When we went to the power plant (on the road past the open switchgear), we saw the ruins of the fourth unit illuminated from below by unnatural yellow-crimson color. There was something surreal about this… We could not believe our eyes”, this was the first impression of Arkadii Uskov of what he saw in the early morning of 26 April 1986. Strong emotions, dozens of questions and thoughts ran in the heads of Viacheslav Orlov and Arkadii Uskov.
E.B. What is your role in mitigation of accident consequences?
Orlov On 26 April, at 4 in the morning, RS-1 deputy manager G. Zavodchikov called me and told about an order of RS-1 manager V. Chugunov for me and A. Uskov to come to the power plant.
I called Arkadii, took the car and we went to the ChNPP.
This is how we get to the power plant that day. This had already been the third priority list of people.
In case of an accident, the dispatcher called the heads of workshops (the so-called automatic alarm system). V. Chugunov (RS-1 manager) with an excellent knowledge of Unit-4 and A. Sitnikov, deputy chief operating engineer of ChNPP Stage I, came there as soon as they heard the alarm. V. Chugunov told that upon the command of V. Briukhanov (ChNPP Director) who has already been in a bunker, he was given the task to find out what happened at Unit-4. V. Chugunov and A. Sitnikov visited almost all places, access to which was possible. The only place they failed to get was the roof, since the door was locked. Unfortunately, despite the fact that they knew the reactor compartment of Unit-4 and were familiar with everything, they could hardly find anything (A. Sitnikov died in the hospital and is buried at the Mitino Cemetery, Moscow. V. Chugunov worked at ChNPP after the accident and is now buried in Slavutych).
After arriving at the station, me and A. Uskov performed a standard walkdown of working places of RS-1 operating personnel. The first and second power units were working at rated power and there were no comments regarding their operation. The radiation safety systems in compartments of these units confirmed the increased radiation background. The personnel were wearing “Lepestok” respirators (masks on the faces). After a while, V. Chugunov who has already stayed at Unit-4 called us and said: “Guys, come to MCR-4, we need your help, because all the others are tired”. It is the usual practice to send engineers, if the situation is unknown. The three of us, me, Arkadii Uskov and Aleksandr Nekhaiev (senior mechanical engineer of RS-1 working shift), went in the direction of Unit-4. Before leaving, we opened an emergency set of individual protective means of RS-1 shift: we took potassium iodide, put plastic shoe covers, gloves and took a mining lamp with us and left all the documents. It was about 7 o’clock in the morning.
We went to the radiation safety monitoring panel to determine dosimetric situation. There we found personnel of the radiation safety shop who emotionally discussed the current situation. At that time, all measuring devices showing doses up to 100 roentgen were checked and remaining radiometers only suited for measuring low-energy radiation and therefore almost all of them went off the scale.
Except for the operators of the shift, A. Sitnikov and V. Chugunov have also been at MCR of Unit 4. The scheme of the repeated forced circulation circuit and some other diagrams lied on the table. A. Sitnikov had already felt bad and sick. Other guys seemed to feel the same. The main task of personnel in emergency conditions is to ensure core cooling. The situation was not clear. Nobody could understand what happened. Specialized devices showed that the load of control and protection system (CPS) pumps, which cooled CPS channels (passing through the core), was normal and meant that the water is pumped. I understood that if the pump is working, then the reactor is intact. However, it turned out that the hydraulic scheme of CPS pumping facility in Unit 4 is different from ours (Stage I): CPS emergency tank and circulation tank (CPS lower tank) are connected by overflow pipe. The pumps when pumping water from the lower tank to the upper tank run some water through the core. When pipes to CPS channels were damaged, the water was pumped to the emergency tank and through the overflow water went to the lower tank. Therefore, the pumps were working, but water did not circulate through the core.
In this situation, it was necessary to ensure water supply to cool the core through the feeding joint from the deaerators of the turbine hall. When the accident occurred, the feeding joint valves operated in automatic mode (to maintain the level in the vapor-liquid separator). At the time of explosion, the electric drives failed (the cables broke down) when the supply valves were closed. We had the task to open the valves at feeding joints to supply water for reactor cooling.
The team that consisted of A. Uskov, V. Orlov, A. Nekhaiev, A. Akimov (ChNPP-4 shift supervisor), L. Toptunov (chief reactor control engineer) started to work. When we have manually opened the valves and heard the sound of water, we came back to the main control room.
When we came back to MCR-4, A. Akimov and L. Toptunov became very ill. They were sent to the first-aid post and then immediately to the hospital. A. Akimov and L. Toptunov died in the hospital. They are buried at the Mitino cemetery. Sasha Nekhaiev went to RS-1 to hand over his shift. He was treated in Moscow, lost both legs and became group 1 disabled.
On the way back, I went to the emergency control room (ECR). It was empty inside. The glass in the windows was broken. ECR was located at elevation 9 and from there one could see the territory of the reactor. When I examined the situation, I saw the plate that fell on the liquid-oxygen transporter, the side wall of the reactor building, ruined piping insulation, air conditioners hanging on wires. The pieces of graphite blocks of the reactor seemed to lay down. As a joke, I asked V. Smagin (ChNPP-4 shift supervisor who took up duty from eight o’clock): “Did these graphite blocks lay here before the accident?” and he answered “Not really, we have cleaned everything to prepare for 1 May”. We did not even want to believe our eyes. It turned out that core components are scattered around the reactor building!..
I then realized that we are in the center of the event whose radius can already be measured as tens of kilometers.
Then, we together with Arkadii, Viktor Smagin and Aleksei Breus (Unit-4 shift that took up duty from eight o’clock) went to open ECCS valves. When all the water from deaerators was pumped to cool the reactor, we came back to RS-1. On our way back, we felt sick. It was obvious that this is because of received radiation dose, so we took a shower in the changing room, changed our cloths and went to the first-aid post. There we received some sort of injection and were sent to the medical unit in Prypiat in the ambulance.
[From the reference on engineering and technical characteristics of Chornobyl NPP design. 19 September 1971. This is the single-circuit NPP. Structurally, the reactor is a cylinder with a diameter of 14.5 m and with a height of 14.75 m located in the concrete well. The core has a diameter of 11.8 m and a height of 7.0 m and consists of 1661 process channels. The process channels are the tubes passing through graphite stack of a special configuration functioning as a moderator of neutrons resulting from nuclear fission reactions. Each process channel has a fuel assembly that consists of two fuel clusters, including two fuel assemblies from 18 fuel rods made of zirconium alloy containing fuel pellets (to 1.8 % by U-235) with enriched uranium dioxide. The general reactor loading is about 204 t. Heat resulting from nuclear fission reaction (the temperature inside the rod with pellets reaches 2300 °С, the temperature at the surface is about 830 °С) is removed by water, which when passing through the process channel (upward) heats to the saturation temperature forming a steam-water mixture containing 17 % of steam. The coolant is pumped through the core by eight reactor coolant pumps with a capacity from 5500 to 12000 m3/h, where at reactor rated power, six RCPs are under operation and two RCPs are on standby. The flow rate of each pump under normal conditions is 8000 m3/h.]
E.B. You have received the high dose in the first hours of the accident and have been transported to the hospital for examination and first aid to treat radioactive exposure. Share your feelings from staying in hospital in such a difficult time.
Orlov. We were examined in the medical unit. All cloths were radioactive, so they were immediately seized. We were sent to the shower, dressed in hospital pajamas, took manganese solution for stomach lavage.
Having woken up after a dropper with saline (in the afternoon of 26 April), we looked out of the window and saw that the cars wash roads in Prypiat with foam. People (residents of Prypiat) are walking through the streets. It was Saturday. In the night from Saturday to Sunday, the emergency medical team from the sixth Clinical Hospital of Moscow came there. The doctors asked everybody, where did they stay and what did they do, and checked other external signs. They preliminary defined the greatest degree of exposure and at night the first group of people was sent to Moscow by the military transport plane.
Uskov. When we stayed in hospital, we wanted to go back to the plant. Everybody were there and we were in the rear! However, the doctors explained what awaited us, and we began to calm down. Radiation is the most democratic striking factor. It spares neither the generals nor the homeless, neither workers nor directors, since everybody is a biological object consisting of 70 % water. Water is known to be ionized. Accordingly, a very different audience stayed in the hospital.
Orlov. On Sunday morning, we were told that we would be sent to Moscow. All were brought to the yard (just in hospital gown). The relatives came to see us off. All of us, nearly 200 people, were put into buses and we passed through Prypiat in Boryspil. Along the roads, there were buses for the evacuation of people from Prypiat.
We were transported immediately to the plane in Borispol without registration. We arrived to the Vnukovo airport and were transferred to the specially prepared buses with seats covered with polyethylene. When we saw this, we felt a little sad that we were considered as radioactively contaminated, because we came from hospital.
During our staying in the hospital, before and after, we constantly discussed the causes of the accident. We also wanted to know when we would come home to Prypiat. However, we did not have any information about the accident.
When we left the hospital, we saw the new asphalt stains. We were told: “Guys, you contaminated everything. The buses are now waste. The plane, probably, as well. Even the new asphalt is put. Everything was changed here, even the curbs you were sitting on!”
E.B. How do you see the further development of the Exclusion Zone 30 years after the Chornobyl accident?
Uskov. The Exclusion Zone has all the conditions to become a place of civilized and safe storage of radioactive waste not only of Chornobyl origin. The management of radioactive waste requires special and constant attention by the government. First of all, this is the creation of efficient system for Exclusion Zone management, sufficient funding (proper using of Radioactive Waste Management Fund), attraction of investments for the implementation of advanced technologies, creation of conditions for fundamental scientific research and arrangement of international scientific fields. In addition to radioactive waste of industrial (energy), scientific and medical origin, there is radioactive waste left after the Chornobyl accident – sites for storage and local disposal (interim storage points). There are RWDS “Buriakivka”, “Khutir Pidlisnyi”, “Stage III”, whose contents need to be transferred to disposal facilities at the Vektor site. We should now think about where to store high-level waste and fragments of damaged fuel, define places to locate storage facilities in deep geological formations (for example, in Western part of the Exclusion Zone, where there are granite massifs of Ukrainian crystalline shield reaching Vilcha (village in Polissia Region of Kyiv Oblast). This part lays in 10-kilometer zone, which in future shall become an area of special industrial use (upon the fact of contamination by transuranic elements and impossibility for residence of the population). The difficulty of task is that the cost for the construction of such a storage facility is very high.
Designs at ChNPP site shall not be limited by moving of NSC over the destroyed Unit-4. Finding solutions for the retrieval of fuel containing materials from the Shelter and funding sources for this unique activity are the most urgent tasks in Ukraine. Each decision is accompanied by significant financial, human and intellectual resources.
I also want to say that the Exclusion Zone should be transferred into the useful area for the economy and energy. The Exclusion Zone is ideal for the further development of renewable energy: there is plenty of territory, the land is cheap, economic conditions are unique…
Uatom.org Editorial Board