Jerry Pournelle RT Category 2, Topic 11 Message 114 Sat Nov 10, 1990 W.MIHALOVITS at 00:56 EST
I've recently been reading a Russian report on Chernobyl written by the man Moscow sent to investigate the accident, Grigority Medvedev. It reveals a lot of things that weren't previously known. Someone asked about the explosion in the core, there were 2 different types of explosions. The control rods were tipped with a graphite end, followed by a meter of empty space (presumably non neutron absorbing material) and then the neutron absorbing material. When the reactor started to go unstable and the operators tripped the plant, the graphite on the tip of the rods caused the reactor to go prompt-critical and a steam explosion occured due to the intense heat . This explosive prevented the rods from fully inserting and shutting down the reactor. Several steam explosions occurred during the accident but it was a hydrogen explosion that destroyed the reactor and the reactor building and started the massive release of contamination.
I've been asked to post a copy of a letter that I've sent some friends on what I've learned about Chernobyl from Medvedev's report and from Russian nuclear expert who have recently been visiting our plant. Please excuse the format
DISCLAIMER (and other excuses)
This the first in my posts on the accident at Chernobyl. Some of this information is from Russian experts who have visited our company recently to see how we do business (on my end, how we train the operators since the inadequacies of the operator's training and plant understanding is one of the underlying causes of the Chernobyl accident), and some is from a report on Chernobyl by Grigority Medvedev. Medvedev participated in the design of Chernobyl, recommended many of the plant's staff, and was sent by Moscow to investigate the accident immediately thereafter. I will sometimes place remarks after "facts" since I have found some of these to be in error or exaggerated. I am relaying this information as I find it, some of it cannot be verified and may be colored by my sources' perceptions
If you find this information too technical or detailed, please let me know. Likewise, if I start sounding like an instructor (occupational hazard: my occupation and your hazard <g>)
For those more interested in Chernobyl now (the affects on the townspeople, workers, etc.) I will cover that, too.
In order to understand how the Chernobyl accident occurred, I think that it's necessary to understand the political climate in the USSR. In 1986, the year that the disaster took place, the soviet union had been operating nuclear power plants for 35 years. Their viewpoint was that fossil fuels would soon run out and that nuclear power was necessary for the USSR to "avoid the wars that would break out in the capitalist nations over fuels."
To facilitate this, they decided to keep the public in ignorance about nuclear power. In a public meeting, the minister on energy and electrification stated "Atomic reactors are ordinary furnaces and the operators controlling them are the stokers." Pravda also supported nuclear power with statements like "Waste from nuclear power engineering, which is potentially very hazardous, is so compact that it can be stored at places isolated from the external atmosphere." It's interesting to note that Chernobyl (and most other Russian plants) had no facilities for storing radioactive wastes. After the accident, one had to be built next to the plant in a highly contaminated area, resulting in high exposure rates to the workers (I don't know the doses received and this may be exaggerated).
Even after the accident, the USSR continues to build more plants, including plans for plants to supplying heating to major cities (located, of course, adjacent to these cities.) One official, publically commenting on the Chernobyl accident, stated "Science requires sacrifices"!
Medvedev states that another reason given for nuclear power (and it's continued importance in the USSR) is to eliminate pollution-causing coal, oil, and gas fired plants. He discounts these reasons because, among other reasons, "Coal plant pollution is local and presents no menace at all". I guess he's never heard of acid rain!
The Soviet Union was so anxious to have nuclear power proceed without question or interference that all news of accidents at nuclear power plants was suppressed. The Three Mile Island accident was discounted as an exaggeration of foreign press (to a great extent, that's true. However, the American nuclear industry learned from this accident and has acted upon what it learned.) Not only was the public kept ignorant but the nuclear profession was, too! Information about all the accidents were kept on a top brass level. I, personally, find this unforgivable. Part of my job is to learn the details of accidents, incidents, and problems at plants throughout the world so we can analyze them and try to ensure that we don't have the same thing happen at work. This information is shared freely (in fact required to be presented to) the operating personnel.
The following is a list of accidents in the Soviet Union preceding Chernobyl.
1971 through 1986 - Beloyarsk AES (Atomic Energy Station) Unit 1. Over a 15 year period there were repeated ruptures and burning of fuel assemblies. This resulted in the release of radioactive nuclides and the overexposure of personnel during subsequent repairs.
1974 - Leningrad Unit 1: Rupture of an intermediate loop (system to transport hot water from the reactor to the steam generators. The steam generators produce the steam to drive the turbine-generators, which produce the electricity.) 3 people killed.
1975 - Partial meltdown. 1.5 million curies of highly radioactive nuclides blown into the atmosphere via a vent pipe.
1977 - Beloyarsk AES Unit 2. Half of the core melted down, took 1 year to repair.
1978 - Unit destroyed by fire when ceiling slab fell on turbine oil reservoir. The control cable burned, resulting in complete loss of reactor control (note: Soviet plants often had the turbine and reactor in the same building. American plants are not only separate physically and electrically with massive missile shields in between, but there are normally 4 independent channels of control and protection that are also completely separate from each other. Should one be destroyed, the others will still work.
1982 - Chernobyl Unit 1: Rupture of central fuel assemblies
1982 - Armenian Unit 1: Turbine building burned. Most operating personnel fled, people flown in from another plant to help the operators that stayed.
1985 - Balakovo Unit 1: Safety valve blew during startup/adjustment operations. 14 people killed by steam.
All of these accidents were results of design flaws or poorly manufactured equipment, procedural violations, or operator error. All could have been prevented or mitigated by properly trained operators.
With the exception of the 2 accidents in 1982, all went unreported. Even operations personnel were not informed and so could not learn from the mistakes. The accidents in '82 were mentioned in passing in an editorial in Pravda.
Sweden and Finland periodically made inquiries to the USSR concerning nuclear accidents since contamination was being carried by the prevailing winds to these countries (I've talked with a Swedish nuclear professional who was one of the first in the free world to know about Chernobyl. The contamination was setting off detectors at his plant!). The soviets denied all information concerning any accidents. A.I. Mayorets, the Minister of Energy and Electrification, ordered the complete ban on information concerning nuclear accidents, as had his predecessor. He also disbanded the main administration for nuclear research and project planning. With no experience or education in nuclear power, he assumed much of the responsibility for the planning of nuclear energy in the USSR.
As I said above, many of the accidents were due to design flaws or equipment failures. The Deputy Chairman of USSR Council of Ministers is to blame for much of this. He would hold AES construction and startup to a deadline regardless of personnel or equipment readiness. Any one opposing him was called a 'hero setting his own deadlines..' and received blemishes on his party record. Consequently, plants were started up with shoddy workmanship, inferior materials, untrained operators, and lacking the necessary safety support equipment.
Supervision of nuclear construction was supervised by A.M. Semenov, a man with hydropower construction experience, only. The Operations Supervisor of all USSR nuclear plants also had no experience or training in nuclear power and had come from a coal fired plant. These men, and many others like them throughout the Russian nuclear industry, were hired because of party standings and personal influence.
The top supervision at Chernobyl were similarly unqualified. The plant manager and chief engineer had experience only with coal fired plants. These men proceeded to fill the departments with cronies from their old plants and ignored warnings about nuclear experience. The chief engineer was transferred to the Balakovo plant and was in charge when the 14 people were killed. It was his violation of procedures and safety practices that resulted in their deaths (officially, the operators were held responsible and were fired and expelled from the party.)
The next chief engineer at Chernobyl (N.M. Fomin) was an electrical engineer from a non-nuclear plant. An experienced reactor specialist had been recommended for the job of chief engineer but was rejected by Moscow because he was only a "tekhnar", an ordinary technician. Fomin was described as a "fierce and exciting manager" and stood well in the party and therefore was given the job. When questioned about his knowledge of nuclear power, he replied that it was a prestigious and ultramodern affair and avoided any real answers.
Towards the end of 1985, Fomin was in a car accident and broke his spine. After his recovery, he returned to work at Chernobyl but seemed to be listless and inattentive. A conference was called to discuss Chernobyl unit 5 due to poor construction progress. At this meeting, concern was expressed over the great number of leaks in the operating units, almost 50 cubic meters of radioactive water per hour. Fittings were not holding and air and drain vent valves were leaking. The manager at Chernobyl (a turbine engineer from a coal fired unit) complained about the problems and stated that it was time for him to move to another job.
The operators at Chernobyl were not much better. Some had previous experience in the nuclear industry but were not really familiar with that particular plant. They did not understand reactor physics or the core's operating characteristics.
In summary, the Soviet's nuclear industry had turned out to be supervised, built, and operated by people with no experience and no training. The few voices of reason were drowned out by party politics and the 'good ole boy' network.
For those who will try to use this as ammo against US nuclear power, I will tell you that these conditions DO NOT EXIST IN THE US! Plants are not built by idiots, started without proper safety equipment, or have untrained, unqualified people in charge or at the controls. *l
Jerry Pournelle RT Category 2, Topic 11 Message 169 Sat Nov 24, 1990 W.MIHALOVITS [Bill M.] at 00:17 EST
This is my second post on Chernobyl. To understand how the accident occurred, I will first give a brief explanation of how the Chernobyl reactor worked, an description of the test that caused the accident, and then the accident itself and the immediate aftermath. Please feel free to ask any questions that you might have.
The Chernobyl reactor was of the RBMK design (don't ask me, I don't speak Russian <g>) The core is a cylinder 14 meters in diameter and 7 meters high. The core is filled with uranium fuel and graphite. Nuclear reactors produce heat by fissioning or splitting the uranium atoms. When a uranium atom is struck by a neutron, one of 2 things can happen; the neutron may simply bounce off the atom, imparting some of it's kinetic energy to it (like a pool ball striking another) or the atom may absorb the neutron. When the atom absorbs the neutron, it may become unstable and split into 2 or more fission products. During this splitting, it releases heat. Multiply that heat by the millions of fissions occurring per second and you have enough to produce the steam needed to drive the turbine generators which produce electricity. Uranium atoms that absorb a neutron without splitting release the excess energy by releasing radiation in the form of neutrons, gammas, or betas.
The fission produces 2 or 3 more neutrons which are necessary to create more fission. Additionally, the fission products radioactively decay, also releasing neutrons. The neutrons produced directly by fission are called 'prompt' neutrons and the ones produced by the decay of fission products are 'delayed' neutrons. This distinction is important in reactor physics because the delayed neutrons are the ones actually used to control the reactor. Should something happen to increase the number of prompt neutrons to the point where the reactor is critical (self sustaining) on prompt neutrons alone, the reactor is said to be prompt critical. This results in power increasing so quickly that the operators cannot control it. Usually so much heat is produced almost instantly that a steam explosion occurs in the reactor.
The neutrons must be slowed or moderated before they can cause fission, neutrons that are moving too fast will more likely bounce off a fuel atom rather than be absorbed by it. The graphite in the RBMK core is the moderator, slowing the neutrons down by giving the neutrons something to bounce off of without being absorbed. (The vast majority of American cores use water as a moderator.) When the neutrons reach a slow enough speed (thermal equilibrium with the fuel) they will be absorbed by any fuel atom that they hit and cause fission.
The reactor can be controlled by changing the moderator so that it slows fewer neutrons down (these neutrons are then either absorbed by nonfuel atoms or leak from the core) or by inserting control rods which absorb the neutrons without causing fission. The rods are typically made of hafnium, silver cadmium, or a combination of both. The rods are inserted from the top of the core, when all rods are fully inserted more neutrons are absorbed than created and the reactor shuts down.
In an RBMK core loaded with fresh fuel, the number of neutrons produced by the fuel exceeds the ability of the rods to absorb neutrons. This is true for all commercial cores and is necessary to overcome neutron 'poisons' (neutron- absorbing fission products) that build up as the core operators. To keep the RBMK core from going critical on its own, some of the fuel assemblies are withdrawn and replaced with stationary control rods (more neutron absorbers). As the core is operated and the neutron poisons build up, the stationary rods are withdrawn and replaced with fuel assemblies. Operating rules at Chernobyl stated that no fewer than 28 - 30 control rods must be inserted in the core. Any fewer than that and conditions may arise where the power cannot be controlled.
In US cores, the fuel rods are fixed and cannot be added or withdrawn during operation. Boron is added to the coolant instead and absorbs the neutrons. Operating rules require that enough boron is present so that under worse case scenarios, the Shutdown Margin (ability to shutdown the core vs the core's ability to produce power) is 1.3:1. In other words, when all control rods are fully inserted (except the one which would have the greatest effect, which is assumed to stick out all the way) we have 30% more shutdown ability than the core has power producing ability.
Water is circulated through the core to remove the heat caused by fission. This water (primary water) goes to steam generators and passes through thousands of inverted U-shaped tubes. Water from the secondary system is sprayed onto those tubes and is turned into steam. The steam then is used to run the turbine generators. The primary water gives up its heat through the U- tubes and is returned to the core to complete the cycle. In this manner, the primary water, which becomes radioactive and carries radioactive contaminates, never comes in direct contact with the water/steam used to drive the turbine generators. Because the primary water also absorbs neutrons, it too controls reactor power. In the RBMK core when the primary water heats up, it will absorb fewer neutrons because hot water is less dense than cool water. Under certain conditions, this can result in the core having a positive power coefficient, as power increases the changes in the core add to the power increase - a positive feedback effect. US cores, using water instead of graphite, usually have a negative power coefficient. The decreased density of the water causes fewer neutrons to be slowed down. As power (and heat) increases, the hotter water moderates fewer neutrons until the power increase stops - a negative feedback. I'm sure that you can see that negative power coefficients are much more stable and safer.
The test that lead to the disaster at Chernobyl was meant to see if the plant could be safely shutdown if the plant were to lose all electrical power. Basically, they were going to see if the turbine generators would produce enough electricity to power the circulating pumps (which remove the core's heat) while the turbine was coasting down to a halt after the reactor was tripped (all control rods fully inserted). This test had been completed successfully on other reactors with a few key differences. On the other plants, the reactors were shutdown first and in a stable condition. The other difference is that the lose of power was only supposed, actual power was still available to the emergency equipment and as a backup to the circulating pumps. At Chernobyl, the engineer proposed starting the test with the reactor critical and actually removing power from the circulating pumps. The emergency diesel generators were disabled and the reserve power supplies disconnected. The idea was to actually deprive the plant of all electrical power.
Additionally, the reactor operators were afraid that if the emergency equipment automatically started as it was designed to do, the cold water that it would inject into the core would cause a thermal shock. Anyone who has had a hot glass shatter under cold water knows what thermal shock can do. To avoid this, the pushbutton which started the safety equipment was disconnected. The control rods would insert but the safety equipment would not start. Automatic starting was also disabled. The test, including set up time, would take about 4 hours. For those 4 hours the core would be without safety equipment.
Many other plants were approached by the engineer but because of the risk involved, no others would do it. When Chernobyl's chief engineer, Fomin (who, as you will recall, had no nuclear training or experience), was asked, he jumped at the chance to have his name associated with such an important test.
In January of 1986, V.P. Bryukhanov, manager of the plant, sent the test to the general designer, Soyuzatomenergo (the part of the USSR Ministry of Power that actually operates the plants) and to the central nuclear review committee for all of the Soviet Union. The general designer and the review committee never approved the test. In fact, they never said anything, they all kept silent. Neither the operating ministry or the plant management seemed concerned by this. The ministry, headed by a man with no nuclear training or experience, had become more of a audit function than an operating one. The bookkeeping and supply departments had grown while the engineering and theory departments diminished to almost nothing. The head of the production department of Soyuzatomenergo (if I gotta wade through all these russian names, you should get a few too!) justified the increasingly frequent emergency situations at nuclear facilities with "Not a single nuclear power plant fully adheres to the operating regulations. This is indeed impossible. Operating experience is constantly making its own corrections and adjustments..." Once again, incompetency and ignorance ruled the day.
At 1 a.m. on April 25, 1986 the operating personnel of Chernobyl unit 4 started to reduce power in preparation for the test. 12 hours later, the number 7 turbine generator was taken off line and power to the circulating pumps transferred to no. 8 turbine generator. At 2 p.m. power to the emergency cooling system was removed to prevent its auto actuation and the 'thermal shock' that the operating crew was so worried about. This was the single biggest mistake made, the emergency cooling equipment would have prevented the steam explosions in the core that caused the release of radioactive particles. The valve to the tank that contained the emergency cooling water was shut and padlocked to prevent anyone from opening it.
Immediately after the safety equipment was disabled, the load dispatcher requested the shutdown be temporarily halted. The load dispatcher coordinates the electrical power output of all generating stations and wanted Chernobyl unit 4 to wait until he had gotten other plants to start up. Operation of the plant continued with the safety equipment disconnected, in violation of operating procedures.
9 hours later, at 11:10 pm, the reduction of power was resumed. The test called for the reactor to be at 700 - 1000 MW of power. But because of the delay in reducing power, neutron poisons started to build up in the core. Because some of the automatic control equipment and instruments were disconnected for the test, the operators were unable to stabilize at this power and reactor power plummeted to 30 MW. The deputy chief engineer started running from one control operator's panel to the next yelling "Dumbbells! You don't know how to do it! Incompetent Failures! You are spoiling the experiment!"
The senior operator and the unit shift chief knew that the reactor was in an unstable condition. They did not fully understand what was occurring in the core and did not know that the core now had a positive reactivity coefficient (positive feedback), but they knew that they could not stay as they were. The deputy chief engineer wanted power returned to 1000 MW for the test. To do so would require reducing the number of control rods in the core to less than minimum allowed by procedure. When the operator and shift chief refused to raise power, the engineer attacked them and ordered them to raise power. Fearing for his job, the senior operator withdrew the control rods and began the power increase. This was 24 minutes before the explosion.
At 1:07 a.m. another circulating pump was started. This was in violation of operation procedure because there was too much coolant flow in the reactor. The senior operator and shift chief looked at the computer which kept track of how many control rods should be inserted. The computer said 28 were needed while only 18 were actually in place. While they mulled this over, the deputy chief engineer strolled up and down telling the other operators "Another 2 or 3 minutes and it will all be done. Cheer up, lads!"
At 1:23:04 the steam control valves to the turbine were shut, starting the coastdown and the experiment. At the same instant, the main circulating pumps filled with steam, reducing cooling flow to the reactor. Reactor power started to increase and at 1:23:40 (36 seconds after the test started) the shift chief decided to trip the reactor. When he pressed the button, the control rods all started to insert into the core. The control rods 8 meters long, a 1 meter graphite tip, 1 meter of neutral material, and then 5 meters of neutron absorbing material. As soon as the graphite tips of the rods entered the core, (graphite, as you will recall, is a moderator and increases power) steam from the circulation pumps also entered the core. Combined with the high temperature of the coolant (and the positive reactivity coefficient) the reactor went prompt-critical. A steam explosion occurred immediately and jammed the control rods, preventing further insertion.
A large chunk of fuel, graphite, and core internal components was ejected from the core. Loud shocks were heard coming from the central hall (the operating area above the reactor) By coincidence, the chief of the reactor shop was entering the central hall just at that moment. In the central hall was a holding tank, containing spent (and highly radioactive) fuel. 2000 350kg blocks formed the floor of the central hall, providing the shielding between the reactor and the central hall. The blocks started jumping up and down as the reactor exploded beneath them. The chief of the reactor shop rushed to tell the control room operators what was happening. He basically threw himself down a 40 meter ladder to get to the operating floor, the elevation that the control room was on. At the same time the hydraulic shocks in the reactor coolant system caused the check valves on the discharge of the circulating pumps to shut, depriving the core of all cooling flow. A steam- zirconium reaction and other chemical and exothermic reactions occurred in the core, giving off hydrogen and oxygen. The zirconium is what the tubes containing the fuel is made of.
Another major steam explosion occurred, rupturing the safety valves on the primary coolant system. Now hydrogen and oxygen began to accumulate in the leaktight containers surrounding the reactor core. At 1:23:58, a series of hydrogen explosions occurred, destroying the reactor and the building. Burning chunks of fuel and graphite went flying everywhere. Some landed on the roof of the turbine hall, setting its asphalt covering on fire.
The upper portion of the core, including about 50 tons of fuel, was vaporized and ejected into the atmosphere by the hydrogen explosions. The debris created a radioactive cloud which moved at an altitude between 1 km and 11 km. The activity of the ejected fuel is estimated to be between 15k - 20k roentgens per hour. Medvedev offers the fact that the atomic bomb dropped on Hiroshima weighed about 4.5 tons for comparison to the 50 tons of fuel ejected into the atmosphere.
The radiation in the area of the plant was initially between 1000 and 1500 roentgens per hour. The nearby city of Pripyat had, for several days, dose rates of 0.5 to 1 roentgen per hour. Had prompt and truthful information been given and action taken, the townspeople would have been spared overexposure to radiation. The effects of this may not be know for many years.
The explosions had ripped away the 130 ton steam generators and had swung the 500 ton slab over the reactor up into the air. The slab fell back onto the reactor in a skewed condition, leaving the core partly uncovered. Roughly half the fuel still remained and graphite in the core was burning intensely.
This post is already 6 pages long. I apologize for the detail but feel that its necessary to understand why the reactor exploded the way that it did. In the next post, I'll discuss the firemen, the fishermen, and others who witnessed the disaster and did not live long thereafter. There are also some interviews with the operators who survived long enough to discuss the accident.
Jerry Pournelle RT Category 2, Topic 11 Message 170 Sat Nov 24, 1990 W.MIHALOVITS [Bill M.] at 00:20 EST
Here is the 3rd post on Chernobyl
About 70 tons of highly radioactive debris was scattered around the site, much of it on the burning turbine building roof. Firemen from the industrial site station responded to fight the fire without knowing the cause. The firemen heard at least 3 separate explosions, there were probably more. The last explosion carried away the reinforced concrete roof, the 50 ton crane and the 250 ton refueling machine and its attached crane. A fireman reported seeing a black fireball erupt over the roof of the turbine building.
Firemen climbed to the roof of the roof of the building to access the damages and another climbed into the remains of the central hall. All knew that they were receiving exposure but were not aware of the dose rate or the consequences. The dose rate at the turbine hall roof was about 20,000 roentgens per hour (r/hr) and the firemen spent a great deal of time up there.
In the control room, confusion reigned. The shift chief kept repeating "I don't know anything! What's happening? We did everything right!" (he kept repeating the latter all the time in the hospital until he died.) The deputy chief engineer ran to the backup control room and pressed the disconnected emergency systems pushbutton and turned off power to the control rod mechanisms to cause them to insert (they could not, they were and still are jammed halfway out). He convinced himself that the reactor was intact, the explosion was a safety control system tank. He looked outside and saw the fire, the debris, and the graphite from the core and still refused to believe that the core was not intact. That is what he reported to emergency personnel arriving and to Moscow.
The shift chief also believed the reactor to be intact and he sent 2 trainees to the turbine hall to manually disconnect the control rods from their drive mechanisms so that they would fall into the core. The explosions had destroyed the lines to the radiation detection instruments, no one knew the level of radiation in the control room or elsewhere. The shift chief did not know he was sending 2 young men to their deaths. The dosimetry department attempted to ascertain the levels with portable instruments. The 1st was a low range meter which read only up to 0.1 r/hr and it was pegged out high. The other instrument, which read up to 1000 r/hr was burned out. The permanent detectors for unit 3 were still operable and read off scale high (I think they had a max of 0.1 r/hr). No other instruments were available expect one in a locker that was buried under rubble.
The trainees worked their way through the rubble to the central hall. They could smell ozone from the intense radiation ionizing the very air and their chests and eyes burned terribly. They saw fire hoses dangling on the reactor side, abandoned by the firemen a few minutes before when the firemen fled as they lost their strength and then consciousness. The trainees could not find anything left of the reactor. They paused in wonder, staring at the blue and red fire coming from the center of the destroyed reactor, receiving fatal doses several times over. They ran back to the control room and reported what they had seen. Both men were sunburned, even under their clothing. They both later died in horrible pain in a Moscow clinic.
The deputy chief engineer, Dyatlov, was still convinced that the reactor was intact. He informed them that they must be wrong, that the hydrogen mixture in the emergency tank ignited and blew the top off the building. "The fire must have been burning debris that fell to the floor. The reactor is intact and needs cooling water."
This caused much time to be wasted and more deaths as people entered the high radiation fields to try to establish cooling water to a nonexistent reactor. This 'information' was repeated all the way back to Moscow, resulting in much confusion and misguided efforts. One man's stupidity and the power that came with his position exacted an awful toll.
Dyatlov then took a tour of the plant with a dosimetrist. Even after seeing all the damage, he refused to believe that the reactor was destroyed. When the dosimetrist informed him that the meters were off scale high at 0.1 r/hr and that the radiation was so high he could smell it, Dyatlov called him names and told him to put the meter "you know where!" By 5 a.m., Dyatlov and the dosimetrist were sunburned and showing signs of radiation sickness and left for medical treatment.
There were 2 operators stationed in a room next to the central hall at the time of the explosion, Kurguz and Genrikh. 4 minutes prior to the explosion Genrikh went into an adjoining room and laid down on a cot to take a short nap. Kurguz sat at his desk and was making an entry in his log when the explosions occurred. The blast blew open the 3 doors between the central hall and the room where Kurguz sat, filling the room with flames and radioactive steam and fuel dust. Kurguz ran through the flames and shut the door. Genrikh jumped off the cot and ran to help his friend, forcing him to lay on the floor where the air was cooler. They waited about 3 minutes until the heat began to recede (the time when the roof was completely open and the flames went up instead of out into the rooms.) Kurguz' face and hands were bleeding badly, his skin hanging by threads. They set off to the control room to report.
Had they taken the most direct (and most dangerous) route, they would have met the 2 trainees sent to investigate the central hall and probably turned them back, saving their lives. As fate would have it, they choose another path. They were met by the deputy chief engineer who, upon seeing the hugh blisters that were already forming on Kurguz, sent them to the medical facility. The 2 operators had received about 600 roentgens each. The medical unit was too far for Kurguz so they went down to the ground floor, broke out a window, and helped him outside to wait for the ambulance that had been called. This turned out to be for the best, the site manager had been so confident in the safety of his 4 units that the medical unit was not open and there were no emergency medical personnel on site.
Other operators rushed to the turbine hall to keep the fire from spreading. They drove wooden plugs into rupture oil lines (upon doing so, one operate sat on the line as if to say "There, take that!" and received a contact burn on his butt), turned off the oil pumps, and manually started the sprinkler system.
The turbine operators were also concerned that the hydrogen used to cool the turbine generators would explode and worked to purge the generators with nitrogen. Had not the operators fought the fires inside the turbine building while the firemen fought them outside and on the roof, the fire would have destroyed the entire turbine building. The roof, along with the firemen on it, would have come crashing down and the fire would have spread to the other units and their reactors. In radiation fields of 500 to 15,000 r/hr they also fought to restore cooling water to the reactor, manually operating valves that were known to take about 4 HOURS to open (they are normally power operated but the explosions had destroyed most of the cables. The equipment still capable of being powered had been deliberately disabled for the test.) By 5 a.m. cooling flow was established to the non-existent reactor core. Since the lines had been torn away with the explosions, the water only soaked the area surrounding the remains of the core, carrying the contamination further and started to short circuit the power lines to the other units. In the soviet plants, the electrical systems are interconnected for 'reliability'. Here, they are kept electrically and physically separate for reliability.. a fire or fault in one unit cannot affect another.
The turbine operators kept calling the control room from a phone near a transformer. Unknown to them a piece of fuel had fallen on the transformer, resulting in a lethal dose to four operators. By 5 a.m., when they had the cooling water re-established, the operators were showing signs of radiation sickness; vomiting, weakness, burning sensations. 4 of the operators received about 350 roentgens and survived. The other 4 received over 1,000 roentgens and did not.
In the last post, I mentioned the reactor shop chief who had observed the blocks jumping up and down over the reactor (Perevozchenko). The explosion occurred before he reached the control room. Without regard for his own safety, he returned to the central hall where the pump operator had been standing his watch. The entire area was gone and fire raged everywhere. The operator had died instantly in the first great explosion. Crawling through this horror, Perevozchenko searched for the operator, stopping to listen for his voice or groans, calling for him. He moved burning pieces of fuel and graphite with his hands, looking to see if the operator was trapped beneath the rubble. Not finding him, he went up to the room where Kurguz and Genrihk had been to search for them. Finally, he headed for the control room to warn them to leave. Perevozchenko, one of the few experienced physicists at Chernobyl, knew that the reactor was destroyed and that the people had to be evacuated. Vomiting almost continuously, losing consciousness for instants, he dragged himself into the control room. When he warned the shift chief (Akimov) that the reactor was destroyed and the people must be led out, Akimov told him that the reactor was safe, he must be confused! Akimov assured him that the firemen would put out the fire and all would be safe, and then sent him off to the medical facility.
Other operators searched the rubble for comrades. In the instrument and monitoring room, trapped beneath a fallen beam and badly burned by steam they found one of the operators. They freed him and carried him on one man's back to the medical facility, only to find the door nailed shut. They sat and waited for help.
The plant manager arrived at the plant at 2:30 a.m.. Akimov informed him that there was a radiation problem but the reactor was intact. The explosion he attributed to the hydrogen in the emergency tank. They were confident that the firemen would soon have everything under control. The manager repeated that report to Moscow.
When the plant's civil defense chief arrived at 3 a.m., he brought his own radiation meter. As he passed through the rubble, he noticed that it was off- scale high at 250 roentgens. He reported this to the plant manager who told him to learn how to use his instrument. There were no levels that high.
At 4:30 a.m. Fomin, the chief engineer arrived and was told the same story that the plant manager had gotten. He was confident that the emergency was under control. After reliefs had arrived, the senior operator who had conducted the test and the shift chief refused to leave, preferring to stay to help. This cost them their lives and gained nothing; they were still operating under the assumption that the reactor was intact. Fomin kept repeating to Moscow and civil defense authorities that the reactor was intact and radiation levels normal. When operators grew ill from the radiation, Fomin simply ordered off duty operators to report and take their places.
The deputy chief of the electrical shop went into the raging turbine hall 3 times to turn off hydrogen flow to the generators. Ordering his younger electricians to stay away, he waded through radioactive water up to his knees to figure out how to restore power to emergency equipment. In the process, the 50 yr old man received over 2500 roentgens. After he was forced to get first aid, where they injected a 'physiological solution' into his vein (any of you medical types care to tell me what they mean? A pain- killer?) he rushed back to the plant where he worked for several more hours. He died a terrible, painful death in Kiev. The unit 3 shift chief ordered his operators to take potassium iodide tablets and to put on breathing masks (one of the major fission products is radioactive iodine. When breathed in, it accumulates in the thyroid and can result in a lethal dose. The potassium iodide tablets saturate the thyroid with iodine so that the radioactive iodine can't be retained.) When he realized that his backup water sources were being used to feed unit 4, he recommended that the unit be shut down. Fomin ordered him to remain operating but he shut it down a short time later. In doing so, he prevented the meltdown of unit 3, the water supplies were soon depleted and unit 3 needed a lot of makeup to compensate for numerous leaks.
****************** This is turning out to be much longer than I had envisioned. I apologize for my longwindedness, but I wanted to show the heroism and stupidity that were displayed. I still have more to cover, especially the firemen and civilians.
Jerry Pournelle RT Category 2, Topic 11 Message 171 Sat Nov 24, 1990 W.MIHALOVITS [Bill M.] at 00:41 EST
Chernobyl post #4
Because the authorities refused, despite overwhelming evidence to the contrary, to believe that the reactor was destroyed no one warned the townspeople of the danger. When the 50 tons of fuel and internals vaporized and blew up into the atmosphere it blew across the town and travelled a great distance. It's path could be traced by the contamination found on the aircraft that had flown through it, on the trains that had passed through it, and by the high levels of contamination along the ground as the heavier particles settled.
At the time of the explosion there were fishermen on the river. Fishing was always good where the warm discharge water re-entered the river. This was about 4 km from unit 4. When the explosion occurred most of the fishermen weren't concerned, they had seen fires at the plant before and the firemen had always handled it. The state had done its job of keeping the public ignorant of nuclear power and its hazards well. Some did leave after suddenly feeling a sudden dryness of the throat, burning in their eyes and an incomprehensible anxiety. In the morning, when the others left, more would take their place and watch the events with curiosity.
Sitting on the bank closest to the plant and directly opposite of the turbine hall were 2 men. One was a local ne'er-do-well while the other was on a business trip from Kharkov. They were catching minnows to use as bait for the big pike. They watched as the firemen climbed to the turbine hall roof and stayed to see them start weaving and collapsing. They saw the deputy chief who climbed up to get a bird's eye view of the reactor (and a fatal dose) so that he could confirm that the reactor was indeed destroyed. They stayed until they had received a dose of over 400 roentgen and became nauseous and dizzy, their eyes burning. Only then did they leave and head back to Pripyat and the medical unit there. From there they went to Moscow where the businessman died.
More men arrived to fish and watch the fire, their ignorance and the authorities reluctance to admit the truth allowed them all to receive considerable exposure.
Valentin Belokon, a pediatrician, was on duty at the medical unit in Pripyat. He was on a call to a patient when they were called from the plant so his assistant went in his stead. At 1:42 a.m. the assistant called to inform the doctor of the situation. The doctor rushed to the plant and had to break down the nailed up door to the medical office. When he got there, the firemen were already showing symptoms of radiation sickness. Belokon did not know the cause of the sickness. He was struck by the firemen's anxiety and their frayed nerves so he injected them with tranquilizers. By the middle of the day more than 100 people had been sent to the medical unit and on-coming personnel had pointed out the graphite that could have come only from the reactor core and still the chief engineer (Fomin) and his deputy (Dyatlov), the plant manager, and the operators refused to believe that the core was no longer intact. Between barked orders, Fomin would weep and hang his head in his hands. Bryukhanov evaded questions from the foreman who asked if there was a problem & should he send the construction workers home from unit 5. The foreman decided that the plant manager was not in control of the situation and sent the workers home at noon.
To be fair, Bryukhanov, the plant manager, had requested permission to evacuate Pripyat but was told "No, don't start a panic." The children were out playing, people were carrying on life as usual. Some noticed particles everywhere, clinging to their clothes and hair. The construction workers went off to work but soon returned, there was an accident at the plant...nothing to be concerned about. The police had blocked access and no one could get through. Some people tried to leave town for various reasons and were turned back by the police, no one could leave.
After lunch trucks came and washed the streets; this wasn't unusual so no one paid much attention, although the sharp-eyed noticed that there was a white foam in the gutters. A group of children rode their bicycles up to the overpass where they could see the plant and watch the fire. The fire was higher than the smokestack and the roaring could be faintly heard even from there. This area was one of the most highly contaminated, the cloud had passed directly over it. The children later developed serious radiation sickness (one recently died from leukemia).
Children were released early from school and warned to stay inside and to clean the house with water. No reason was given but people were now starting to realize that a serious problem was occurring. By evening almost everyone knew that an accident had occurred but since all the stores and other institutions were still open, it must not be so dangerous. A metallic odor was in the air, a sharp taste that one man likened it to testing a battery with your tongue. No one could call the plant, the phones had been disconnected to prevent information leaking out.
The wife of the shift chief (Akimov) grew concerned when her husband didn't come home at the end of his shift. She couldn't get through on the phones and no one could tell her a thing. It was afternoon before she learned that he was in the medical ward. They wouldn't let her see him so she snuck around to a window in his ward. They talked through the window and she could see that his face was a reddish brown. He was excited to see her, kept telling her how much he loved her and his boys. He warned her to go home and keep the children off the street. He seemed in high spirits and this reassured her considerably. That was the last time she saw her husband. There were no funeral services for him or the other operators that died, each was soldered into a zinc lined casket and buried in a new cemetery.
As was a normal habit, many townspeople went to the roof of the local hotel to sunbathe during their lunch hours. They commented on how strong the sun was that day and how they burned quickly and invited their friends to join them on the roof. Later that evening, these people began to vomit and complain of a burning pain. They were taken off to the medical unit and from there to Kiev or Moscow.
Members of the government commission flew in from Moscow. Their mission was to study the accident, repair the damages and get the reactor back on-line as soon as possible. They were all buoyed by the 'knowledge' that the reactor had stood up to this accident and that cooling water was being fed to it. By evening they had arrived and toured the plant. A helicopter and photographer were located to survey the damage from the air. No one had masks, protective clothing, or radiation meters. The pilot did have a dosimeter (a self- contained detection device the size of a pen. You look through it to see a small meter and read your accumulative dose). After only a few minutes over the reactor, the pilot casually announced that they had already received 10 rads. Only at that point, when outside authorities themselves had viewed the damage and had photographs, did they even begin to discuss the POSSIBILITY that the reactor was destroyed. The ones who saw it, knew. The others had to be convinced. The civil defense general was the first to assess the situation correctly and recommend that the trains and busses be stopped, the roads blocked off, and the town and plants evacuated. The civil defense chief told them of the radiation levels he had measured and reported. The medical officer reported that the examinations of the operators and firemen indicated that they had received 3 to 5 times the lethal dose of radiation. Still the head of the government commission, Minister Mayorets, stated that "the danger is clearly being exaggerated" and announced an intermission.
At 7 p.m., almost 18 hours after the accident, the deputy chairman of the USSR Council of Ministers arrived at Chernobyl. He listened to the civil defense people and the dosimetrists and others. Then he turned on Mayorets and forced him to admit that the plant and reactor were destroyed. Now the evacuation and other protective actions were finally ordered. He invited everyone to brainstorm, to come up with ideas on how to extinguish the fire in the reactor.
Water was no good, most of it seemed to evaporate before even coming near the base of the flames. It was here that the idea was born to put out the fire with sand from helicopters.
1100 busses were ordered from Moscow and Kiev for the evacuation, planned for the morning of the 27th. On that morning, civil defense crews toured the town, warning people to prepare for an evacuation that would only last 3 days or so. They were allowed to bring only the bare minimum and many left without money or cherished items. The evacuation began by 2 pm; the busses went up each street and collected people outside of their homes. On the roads leading out of Pripyat the busses got stuck in a human traffic jam. An exodus of the people who were too scared to wait for the busses. The evacuation path followed the same path as the radioactive plume from the damaged plant and more exposure was received from the contaminated dust that was kicked up. Decontamination was never considered for the evacuation vehicles and contamination was tracked to Moscow, Kiev, and many other places.
After the town was emptied, the civil defense crews went to the farms and fields nearby. Many of the people didn't know of the accident. The ones that did had no idea of the danger and some had to be forcibly removed. All livestock was shot, which some may consider conservative but I consider overreaction. No one tried to determine the extent of their contamination until days later and decontamination wasn't considered. About a week after the accident measurements on some pigs that had escaped the slaughter showed about 50 r/hr.
The townspeople had to leave their pets behind. According to G. Medvedev the "radioactive dogs first gobbled up the radioactive cats and then formed packs". These packs reportedly attacked livestock and threatened people. A group of hunters was assembled and in 3 days the last of the dogs had been destroyed (April 29th). That means the hunters were assembled on the 27th, the day of the evacuation. I doubt that the dogs formed packs and attacked people on the first day, especially considering that people didn't start leaving until 2 p.m.. Again, I think that Mr. Medvedev gave the official version and unofficially people overreacted and killed all the 'radioactive' pets. While I'm discussing this, I find it interesting that a nuclear professional would call the animals (and he uses the term on people, cars, etc.) radioactive. They were contaminated, not radioactive. Something radioactive is decaying to a more stable state by emitting radiation. Contamination is radioactive particles in the environment or other places, such as the particles clinging to the pets (contamination tends to have a high static charge and would cling to hair and clothes). This distinction is important to professionals, especially when it comes to treating radiation sickness, and for me casts some doubts on Mr. Medvedev's own qualifications. Within his report he also states that 1 roentgen a year yields a 50% likelihood of mutation, a meaningless statement that sounds like something to scare small childrin.
THE REACTOR FIRE
Although the fires in the turbine building and surrounding areas had been extinguished by 5 a.m., the reactor still burned with a flame taller than the unit's 150 meter smokestack (which is really a ventilation stack designed to discharge any radioactive gaseous releases high into the air for maximum dispersal). Water was ineffective and the firemen only received more exposure when they tried. They decided to drop bags of sand from helicopters to quench the fire. While someone went into the countryside to round up 'recruits' the air force general and 2 deputy chiefs grabbed bags and shovels and headed to a pile of sand near the river. In their "city clothes" and with the general in his uniform they started filling bags with sand. The general would not allow his pilots to help, their hands had to be steady for the dangerous flying that they would do. One of the deputies finally grabbed nearby managers and their assistants and pressed them into work. In the middle of it all, one came up with a list of benefits that they would be awarded for doing this work and insisted on getting it approved.
150 volunteers were brought in from the nearby farms and together they started loading the helicopters. Operations personnel and others familiar with the plant accompanied the pilots to guide them in his 'bombing runs'. Initially the dose rate at the dumping height of 110 meters was 500 r/hr. It increased to 1800 r/hr as the dumping continued, probably due to the amount of contamination that was kicked up each time a load was dropped. The general and the 2 deputy chiefs soon were disabled and sent to Kiev for treatment. The same happened to the first 27 crews working there. It wasn't until the 2nd or 3rd day of dumping that the pilots thought of placing lead sheets under the seats and wearing respirators to reduce their exposure.
The air force general decided to use parachutes strapped beneath the helicopters to hold larger amounts of sand and speed the dumping process. Between April 27th and May 2nd, they dropped over 5,000 tons of material into the reactor.
The government purchased several remote control robots from a West German firm for 1 million gold rubles. These robots were to pick up the fuel and graphite blocks and place them in shielded areas. A good idea, but it failed because the ground was not level enough.
They were lifted to the roofs but became entangled in the abandoned fire hoses. The smaller fuel pieces and graphite blocks were collected by hand, resulting in incredible exposures (the graphite blocks were reading over 2,000 r/hr)
Remote controlled dozers were brought in to clear the area of large graphite blocks and other heavy debris. The russian ones had to be started by hand and men entered high radiation areas to do so. The Japanese ones were started by remote control and became the machine of choice. Millions of rubles had supposedly been spent to develop and build equipment to handle emergencies like this. When the time came to use them, they did not exist. Men were recruited to do this dangerous work with promises of benefits to paid to their families if they died. The divers who were asked to swim through highly contaminated and radioactive water were told that the man who opened the drain valve would, if he died, be given a car, a dacha (summer cottage), apartment, and support of their family for life.
Decontamination was not performed on the vehicles used around the site, resulting in 3 - 5 r/hr dose rates to the occupants. Radiation meters were scarce and most often of too low a range to be useful and there were few respirators. Dosimeters were stolen as souvenirs.
To cool the reactor it is decided to lay pipes beneath its concrete foundation slab, the pipes to carry liquid nitrogen to freeze the area. They tried to blast holes but found that the sandy soil absorbed the denotations with little results. Finally they decided to cut a hole in the wall and feed the pipeline through the building and to the reactor.
Concrete was brought in to seal the reactor to prevent the sand and other debris from being dislodged. The concrete was piped in to reduce exposures. Normal welders were not used to construct the piping because they will be needed to build new nuclear power plants. The military was asked to provide its welders (presumably expendable). In the planning that followed it became commonplace to hear "we will stake 2 or 3 lives on this" as they used up people left and right.
The medical treatment was poorly organized and mostly inadequate and inappropriate. The medical units soon became contaminated since none of the patients had any decontamination performed before being brought in. Decontamination was performed at the clinic but it was done sloppily without a real understanding of what was involved. The doctors and nurses soon became contaminated, as did the beds, halls, chairs, and everything else in sight.
Many patients were given only tranquilizers or pain killers. Although the patients were categorized according to their exposure and likelihood of death with the most severe receiving the most attention, proper care was not always given. To the best of my understanding, the basics of proper care consists of massive blood transfusions (since blood forming organs are the most susceptible to radiation), bone marrow injections (same reason), and antibiotics to fight the inevitable infections. A sterile environment is necessary to cut down on the chance of infection. Yet women from town were brought in to literally swamp the place out in an effort to remove decontamination. These women were brought in without any precautions or change of clothing (many tracked contamination back to the cities and homes). The patients were allowed to wander, especially to smoke, and although they weren't supposed to meet family, many did. One highly contaminated individual refused to have his head shaved and then went back home, resulting in overexposure to his family. Many of the worse exposed men were never given anything beyond a tranquilizer. I also find it interesting that Mr. Medvedev never mentions the medical assistance from other countries.
I won't go into the grisly details of their conditions or deaths, but I will discuss the funerals. 26 people died within the first months, most within the first few days. The 6 firemen received honors and were hailed as heros. The deputy chief of the electrical shop who waded through the radioactive water was posthumously awarded the Order of Lenin, the electrician who worked besides him was awarded nothing. A contractor who was there for pump vibration testing had stayed in the burning turbine hall to assist the operators and received a fatal dose; he was buried without notice. The engineers and operations personnel who were every bit as courageous and heroic as the firemen were not only deprived of the honors they deserved, their graves were desecrated by people who blamed them for the accident. They were never 'officially' blamed but the government had considered placing reprimands on their party records. To the people, this was as good as a condemnation. The photographs on the gravestones were removed and destroyed and the traditional gifts of sausage, candy, flowers, etc., that graced the graves of the firemen were missing or removed.
26 men and women soldered into zinc caskets, most buried without the recognition of their sacrifices and most killed needlessly because of incredible ignorance and denial. 26 souls lost because of politics and cronyism. Gone because a government agency wouldn't admit that a design was flawed and dangerous.
And what of the others? What of the children of Pripyat and their parents? How many more lives will be lost from cancer or other diseases? How many children will never be born because of the sterility and miscarriages caused by the radiation? How many will be born with birth defects? What will be the ultimate price of the stupidity, pride, and politics? We may never know.
This is the last of the planned posts. If I find more information, especially the current condition of the town or its residents, I'll pass that along as I find it. Bill PS: please excuse the misspellings and typos.