Chernobyl accident

The Chernobyl accident occurred on April 26, 1986, at the Chernobyl nuclear power plant (originally named after Vladimir Lenin) in Ukraine (then part of the Soviet Union). It is regarded as the worst accident in the history of nuclear power. Because there was no containment building, a plume of radioactive fallout drifted over parts of the western Soviet Union, Eastern Europe, Scandinavia, UK, and the eastern United States. Large areas of Ukraine, Belarus, and Russia were badly contaminated, resulting in the evacuation and resettlement of roughly 200,000 people. About 60% of the radioactive fallout landed in Belarus.

The accident raised concerns about the safety of the Soviet nuclear power industry, slowing its expansion for a number of years, while forcing the Soviet government to become less secretive. The now-separate countries of Russia, Ukraine, and Belarus have been burdened with continuing and substantial costs for decontamination and health care because of the Chernobyl accident. It is difficult to accurately tally the number of deaths caused by the events at Chernobyl, as most of the expected long-term fatalities, especially those from cancer, have not yet actually occurred, and will be difficult to attribute specifically to the accident. A 2005 IAEA report attributes 56 direct deaths; 47 accident workers and 9 children with thyroid cancer, and estimates that as many as 4,000 people may ultimately die from long term accident-related illnesses. Greenpeace, amongst others, disputes the study's conclusions.

The plant

The Chernobyl station (51°23′14″N, 30°06′41″E) is situated at the settlement of Pripyat, Ukraine, 11 miles (18 km) northwest of the city of Chernobyl, 10 miles (16 km) from the border of Ukraine and Belarus, and about 70 miles (110 km) north of Kiev. The station consisted of four reactors, each capable of producing 1 GW of electric power (3.2 gigawatts of thermal power), and the four together produced about 10% of Ukraine's electricity at the time of the accident. Construction of the plant began in the 1970s, with reactor No. 1 commissioned in 1977, followed by No. 2 (1978), No. 3 (1981), and No. 4 (1983). Two more reactors (No. 5 and No. 6, also capable of producing 1 gigawatt each) were under construction at the time of the accident.

The four plants were designed as a type of reactor called RBMK-1000.

The accident

On Saturday, April 26, 1986, at 1:23:58 a.m. local time, the unit 4 reactor of the Chernobyl power plant—known as Chernobyl-4—suffered a catastrophic steam explosion that resulted in a fire, a series of additional explosions, and a nuclear meltdown.

Causes

There are two conflicting official theories about the cause of the accident. The first was published in August 1986 and effectively placed the blame solely on the power plant operators. The second theory was published in 1991 and attributed the accident to flaws in the RBMK reactor design, specifically the control rods. Both commissions were heavily lobbied by different groups, including the reactor's designers, Chernobyl power plant personnel, and the government. Some independent experts now believe that neither theory is completely correct.

Another important factor contributing to the accident was that the operators were not informed about some problems with the reactor. According to one of them, Anatoli Dyatlov, the designers knew that the reactor was dangerous in some conditions but intentionally concealed this information. Contributing to this was that the plant's management was largely composed of non-RBMK-qualified personnel: the director, V.P. Bryukhanov, had experience and training in a coal-fired power plant. His chief engineer, Nikolai Fomin, also came from a conventional power plant. Anatoli Dyatlov himself, deputy chief engineer of Reactors 3 and 4, only had "some experience with small nuclear reactors", namely small versions of the VVER nuclear reactor that were designed for the Soviet Navy's nuclear submarines.

In particular,

• The reactor had a dangerously large positive void coefficient. Put simply, this means that if bubbles of steam form in the reactor coolant water, the nuclear reaction speeds up, leading to a runaway reaction if there is no other intervention. Even worse, at low power output, this positive void coefficient was not compensated by other factors, which made the reactor unstable and dangerous. That the reactor was dangerous at low power was counter-intuitive and unknown to the crew.

• A more significant flaw of the reactor was in the design of the control rods. In a nuclear reactor, control rods are inserted into the reactor to slow down the reaction. However, in the RBMK reactor design, the control rod end tips were made of graphite, the extenders (the end areas of the control rods above the end tips, measuring 1m in length) were hollow and filled with water, while the balance of the control rod - the truly functional area, absorbing the neutrons and thereby halting the reaction - were made of boron carbide.

For the initial few moments when control rods of this design are inserted into the reactor, coolant was displaced by the graphite ends of the rods. The coolant (water), a neutron absorber, was therefore replaced by graphite, a neutron moderator - that is, a material that enables the nuclear reaction rather than slow the reaction down. For the first few seconds of control rod activation the rods increase the reactor's speed, rather than the desired effect (of decreasing the reaction). This behaviour is rather counter-intuitive and was not known to the reactor operators.

• The operators were careless and violated the procedures, partly due to them being unaware of the reactor's design flaws. Also, several procedural irregularities contributed to the cause of the accident. One was insufficient communication between the safety officers and the operators in charge of an experiment being run that night.

It is important to note that the operators switched off many of the reactor's safety systems, which was prohibited by the published technical guidelines unless the safety systems malfunction.

According to a Government Commission report published in August 1986, operators removed at least 204 control rods from the reactor core (out of a total of 211 for this reactor model), leaving seven. The same guidelines (noted above) prohibit operation of the RBMK-1000 with fewer than 15 rods inside the core zone.

Events

On April 25, 1986, the Unit 4 reactor was scheduled to be shut down for routine maintenance. It had been decided to use this occasion as an opportunity to test the ability of the reactor's turbine generator to generate sufficient electricity to power the reactor's safety systems (in particular, the water pumps) in the event of a loss of external electric power. Reactors such as Chernobyl have a pair of diesel generators available as standby, but these do not activate instantaneously—the reactor was, therefore, to be used to spin up the turbine, at which point the turbine would be disconnected from the reactor and allowed to spin under the force of its own rotational inertia, and the aim of the test was to determine whether the turbines in the rundown phase could sufficiently power the pumps while the generators were starting up. The test was successfully carried out previously on another unit (with all safety provisions active) and the outcome was negative (that is, the turbines generated insufficient power in the rundown phase to power the pumps), but additional improvements were made to the turbines which prompted the need for another test.

The power output of the Chernobyl-4 reactor was to be reduced from its normal capacity of 3.2 GW to 700 MW in order to conduct the test at a safer, low power. However, due to a delay in beginning the experiment the reactor operators reduced the power level too rapidly, and the actual power output fell to 30 MW. As a result, the concentration of the nuclear poison product xenon-135 increased (this product is typically consumed in a reactor under higher power conditions). Though the scale of the power drop was close to the maximum allowed by safety regulations, the crew's management chose not to shut down the reactor and to continue the experiment. Further, it was decided to 'shortcut' the experiment and raise power output only to 200 MW. In order to overcome the neutron absorption of the excess xenon-135, the control rods were pulled out of the reactor somewhat farther than normally allowed under safety regulations. As part of the experiment, at 1:05 AM on April 26, the water pumps which were to be driven by the turbine generator were turned on; the water flow generated by this action exceeded that specified by safety regulations. The water flow increased at 1:19 A.M.—since water also absorbs neutrons, this further increase in the water flow necessitated the removal of the manual control rods, producing a very unstable and dangerous operating condition.

At 1:23:04 A.M., the experiment began. The unstable state of the reactor was not reflected in any way on the control panel, and it does not appear that anyone in the reactor crew was fully aware of danger. Electricity to the water pumps was shut off, and as they were driven by the inertia of the turbine generator the water flow rate decreased. The turbine was disconnected from the reactor, increasing the level of steam in the reactor core. As the coolant heated, pockets of steam formed in the coolant lines. The particular design of the RBMK graphite moderated reactor at Chernobyl has a large positive void coefficient, which means that the power of the reactor increases rapidly in the absence of the neutron-absorbing effect of water, and in this case, the reactor operation becomes progressively less stable and more dangerous. At 1:23:40 A.M. the operators pressed the AZ-5 ("Rapid Emergency Defense 5") button that ordered a " scram"—full insertion of all control rods, including the manual control rods that had been incautiously withdrawn earlier. It is unclear whether it was done as an emergency measure, or simply as a routine method of shutting down the reactor upon the completion of an experiment (the reactor was scheduled to be shut down for routine maintenance). It is usually suggested that the scram was ordered as a response to the unexpected rapid power increase. On the other hand, Anatoly Dyatlov, chief engineer on Chernobyl nuclear station at the time of the accident, writes in his book:

"Prior to 01:23:40, systems of centralized control ... didn't register any parameter changes that could justify the scram. Commission ... gathered and analyzed large amount of materials and, as stated in its report, failed to determine the reason why the scram was ordered. There was no need to look for the reason. The reactor was simply being shut down upon the completion of the experiment."

Due to the slow speed of the control rod insertion mechanism (18–20 seconds to complete), the hollow tips of the rods and the temporary displacement of coolant, the scram caused the reaction rate to increase. Increased energy output caused the deformation of control rod channels. The rods became stuck after being inserted only one-third of the way, and were therefore unable to stop the reaction. By 1:23:47 the reactor jumped to around 30 GW, ten times the normal operational output. The fuel rods began to melt and the steam pressure rapidly increased causing a large steam explosion, displacing and destroying the reactor lid, rupturing the coolant tubes and then blowing a hole in the roof.

To reduce costs, and because of its large size, the reactor was constructed with only partial containment. This allowed the radioactive contaminants to escape into the atmosphere after the steam explosion burst the primary pressure vessel. After part of the roof blew off, the inrush of oxygen—combined with the extremely high temperature of the reactor fuel and graphite moderator—sparked a graphite fire. This fire greatly contributed to the spread of radioactive material and the ultimate contamination of outlying areas.

There is some controversy surrounding the exact sequence of events after 1:22:30 local time due to the inconsistencies between eyewitness accounts and station records. The version that is most commonly agreed upon is described above. According to this theory, the first explosion happened at approximately 1:23:47, seven seconds after the operators ordered the " scram". It is sometimes claimed that the explosion happened 'before' or immediately following the scram (this was the working version of the Soviet committee studying the accident). This distinction is important, because, if the reactor went critical several seconds after the scram, its failure would have to be attributed to the design of the control rods, whereas the explosion at the time of the scram would place the blame on the operators. Indeed, a weak seismic event, similar to a magnitude-2.5 earthquake, was registered at 1:23:39 in the Chernobyl area. This event could have been caused by the explosion or could have been completely coincidental. The situation is complicated by the fact that the "scram" button was pressed more than once, and the person who actually pressed it died two weeks after the accident from radiation poisoning.

Radioactive release (source term)

It is clear that rather than being an event which renders the site dangerous forever, the dose rate at the accident site decreased even before the effect of decontamination is taken into account.

A short report on the release of radioisotopes from the site can be read at the OSTI web site at [2]. A more detailed report can be downloaded from the OECD web site's public library here as a 1.85MB PDF file.

At different times after the accident, different isotopes are responsible for the majority of the external dose. The dose which has been calculated is for a person standing in the open from external gamma irradation. The gamma dose to a person in a shelter or the internal dose is harder to estimate.

Because the fission products page has a detailed discussion of the properties of those fission products which are most irksome in a nuclear accident or waste, no detailed discussion will be made here. Only a short description of the radioisotopes released will be made here.

It is important to note that the release of the radioisotopes from the nuclear fuel was largely controled by their boiling points, and that the majority of the radioactivity present in the core was retained in the reactor.

• All of the noble gases, including ( Kr and Xe) contained within the reactor were released immediately into the atmosphere by the first steam explosion.

• About 55% of the radioactive iodine in the reactor was released, as a mixture of vapour, solid particles and also in the form of organic iodine compounds.

• Cesium and tellurium were released in aerosol form.

Two sizes of particles were released, the small particles were 0.3 to 1.5 micrometer ( aerodynamic diameter) while the large were 10 micrometer in size. The larger particles contained about 80 to 90% of the released non volitle radioisotope (⁹⁵ Zr, ⁹⁵ Nb, ¹⁴⁰ La, ¹⁴⁴ Ce and the transuranium elements { neptunium, plutonium and the minor actinides) embedded in a uranium oxide matrix.

Protection offered by the walls against the external gamma dose

Depending on the nature of a building, the structure can either offer a large degree of protection or a small degree of protection. The best protection would be offered by a room with stone or concrete walls which has no windows. A 20 cm thickness of concrete will offer a protection factor of at least 50. However the doors and windows will allow paths for gamma rays to enter the room. Also the contamination on the roof {and skyshine (scattering off of air molecules)} will cause some radiation to come from above. Hence the best shielding will be offered by a windowless room (or basement) in a multistory building such as a block of flats which has concrete floors. See fallout shelter for details.

Immediate crisis management

The scale of the tragedy was exacerbated by the incompetence of local administration and lack of proper equipment. All but two dosimeters present in 4th reactor building had limits of 1 milliroentgen per second. The remaining two had limits of 1000 R/s; access to one of them was blocked by the explosion, and the other one broke when turned on. Thus the reactor crew could only ascertain that the radiation levels in much of the reactor building were above 4 R/h (true levels were up to 20,000 roentgen per hour in some areas; lethal dose is around 500 roentgen over 5 hours).

This allowed the chief of reactor crew, Alexander Akimov, to assume that the reactor was intact. The evidence of pieces of graphite and reactor fuel lying around the building was ignored, and the readings of another dosimeter brought in by 4:30 A.M. local time were dismissed under the pretext that the new dosimeter must have been defective. Akimov stayed with his crew in the reactor building until morning, trying to pump water into the reactor. None of them wore any protective gear. Most of them, including Akimov himself, died from radiation exposure during the three weeks following the accident.

Shortly after the accident, firefighters arrived to try to extinguish the fires. They were not told how dangerously radioactive the smoke and the debris were. The fire was extinguished by 5 A.M., but many firefighters received high doses of radiation. The government committee, formed to investigate the accident, arrived at Chernobyl in the evening of April 26. By that time two people were dead and fifty-two were hospitalized. During the night of April 26– April 27 — more than 24 hours after the explosion—the committee, faced with ample evidence of extremely high levels of radiation and a number of cases of radiation exposure, had to acknowledge the destruction of the reactor and order the evacuation of the nearby city of Pripyat. In order to reduce baggage, the residents were told that the evacuation would be temporary, lasting approximately three days. As a result, Pripyat is still complete with personal belongings that can never be moved due to radiation. From eyewitness accounts of the firefighters involved before they died, (as reported on the BBC television series Witness) one described his experience of the radiation as "tasting like metal", and feeling a sensation similar to that of pins and needles all over his face.

The water that had hurriedly been pumped into the reactor building in a futile attempt to extinguish the fire had run down underneath the reactor floor to the space underneath. The problem presented by this was the fact that the smouldering fuel and other material on the reactor floor was starting to burn its way through this floor, and was being made worse by materials being dropped from helicopters, which simply acted as a furnace to increase the temperatures further. If this material came into contact with the water, it would have generated a thermal explosion which would have arguably been worse than the initial reactor explosion itself, and would have, by many estimates, rendered land in a radius of hundreds of miles from the plant uninhabitable for at least one hundred years.

In order to prevent this, "liquidators"—members of the army and other workers—were sent in as cleanup staff by the Soviet government. Two of these were sent in wet suits to release the valve to vent the radioactive water, and thus prevent a thermal explosion. These men, just like the other liquidators and firefighters that helped with the cleanup, were not told of the danger they faced. The two men saved millions by releasing the water, yet it is likely they did not even reach the surface again before they died.

The worst of the radioactive debris was collected inside what was left of the reactor. The reactor itself was covered with bags with sand, lead and boric acid thrown off helicopters (some 5,000 tons during the week following the accident). A large concrete sarcophagus was hastily erected to seal off the reactor and its contents.

Immediate results

203 people were hospitalized immediately, of whom 31 died (28 of them died from acute radiation exposure). Most of these were fire and rescue workers trying to bring the accident under control, who were not fully aware of how dangerous the radiation exposure (from the smoke) was (for a discussion of the more important isotopes in fallout see fission products). 135,000 people were evacuated from the area, including 50,000 from the nearby town of Pripyat, Ukraine. Health officials have predicted that over the next 70 years there will be a 2% increase in cancer rates in much of the population which was exposed to the 5–12 (depending on source) E Bq of radioactive contamination released from the reactor. An additional 10 individuals have already died of cancer as a result of the accident.

In January 1993, the IAEA issued a revised analysis of the Chernobyl accident, attributing the main root cause to the reactor's design and not to operator error. The IAEA's 1986 analysis had cited the operators' actions as the principal cause of the accident.

Soviet scientists have reported that the Chernobyl Unit 4 reactor contained about 180-190 metric tons of uranium dioxide fuel and fission products. Estimates of the amount of this material that escaped range from 5 to 30 percent. Because of the intense heat of the fire, much of this was lofted high into the atmosphere (there not being a complete containment building to catch it), where it spread.

Contamination from the Chernobyl accident was not evenly spread across the surrounding countryside, but scattered irregularly depending on weather conditions. Reports from Soviet and Western scientists indicate that Belarus received about 60% of the contamination that fell on the former Soviet Union. But a large area in the Russian Federation south of Bryansk was also contaminated, as were parts of northwestern Ukraine.

The initial evidence in other countries that a major exhaust of radioactive material had occurred came not from Soviet sources, but from Sweden, where on April 27 workers at the Forsmark Nuclear Power Plant (approximately 1100 km from the Chernobyl site) were found to have radioactive particles on their clothes. It was Sweden's search for the source of radioactivity, after they had determined there was no leak at the Swedish plant, that led to the first hint of a serious nuclear problem in the Western Soviet Union.

The effects of the accident

The workers involved in the recovery and cleanup after the accident received high doses of radiation. According to Soviet estimates, between 300,000 and 600,000 people were involved in the cleanup of the 30 km evacuation zone around the reactor, but many of them entered the zone two years after the accident. [3]

Some children in the contaminated areas were exposed to high radiation doses of up to 50 grays (Gy) because of an intake of radioactive iodine-131, a relatively short-lived isotope with a half-life of 8 days, from contaminated milk produced locally. Several studies have found that the incidence of thyroid cancer among children in Belarus, Ukraine and Russia has risen sharply. So far, no increase in leukemia is discernible, but this is expected to be evident in the next few years along with a greater, though not statistically discernible, incidence of other cancers. There has been no substantiated increase attributable to Chernobyl in congenital abnormalities, adverse pregnancy outcomes or any other radiation-induced disease in the general population, either in the contaminated areas or further afield.

Long-term health effects

Right after the accident, the main health concern involved radioactive iodine, with a half-life of eight days. Today, there is concern about contamination of the soil with strontium-90 and caesium-137, which have half-lives of about 30 years. The highest levels of caesium-137 are found in the surface layers of the soil where they are absorbed by plants, insects and mushrooms, entering the local food supply.

Soviet authorities started evacuating people from the area around Chernobyl within 36 hours of the accident. By May 1986, about a month later, all those living within a 30 km (18 mile) radius of the plant—about 116,000 people—had been relocated. This region is often referred to as the Zone of alienation.

The issue of long-term effects of Chernobyl disaster on civilians is very controversial. Over 300,000 people were resettled because of the accident; millions lived and continue to live in the contaminated area. On the other hand, most of those affected received relatively low doses of radiation; there is little evidence of increased mortality, cancers or birth defects among them; and when such evidence is present, existence of a causal link to radioactive contamination is uncertain.

In September 2005, a report by the Chernobyl Forum, comprising a number of agencies including the International Atomic Energy Agency, the World Health Organization, UN bodies and the Governments of Belarus, the Russian Federation and Ukraine, put the total predicted number of deaths due to the accident at 4,000. This predicted death toll includes the fifty workers who died of acute radiation syndrome as a direct result of radiation from the disaster, nine children who died from thyroid cancer and an estimated 3,940 people who could die from cancer as a result of exposure to radiation. (see the World Health Organisation News Release)

Comparison with other disasters

The Chernobyl accident was a unique event, on a scale by itself. It was the first time in the history of commercial nuclear electricity generation that radiation-related fatalities occurred, and was for a long time the only such incident (since then an accident at the Japanese Tokaimura nuclear fuel reprocessing plant on September 30, 1999, resulted in the radiation related death of one worker on December 22 of that same year and another on April 27, 2000).

The Chernobyl incident has also been compared to the Bhopal disaster. On December 3, 1984, a Union Carbide plant in Bhopal, India leaked 40 tons of toxic methyl isocyanate gas, which killed at least 15,000 people, and injured anywhere from 150,000 to 600,000 others.

Other manmade disasters with death tolls exceeding the Chernobyl Disaster include:

• Banqiao Dam, 1975, in China, 171,000 killed.
• Great Smog of 1952, London, England about 12,000 killed.

Chernobyl after the accident

The trouble at the Chernobyl plant itself did not end with the disaster in Reactor No. 4. The damaged reactor was sealed off and 200 metres of concrete were placed between the disaster site and the operational buildings. The Ukrainian government continued to let the three remaining reactors operate because of an energy shortage in the country. A fire broke out in Reactor No. 2 in 1991; the authorities subsequently declared the reactor damaged beyond repair and had it taken offline. Reactor No. 1 was decommissioned in November 1996 as part of a deal between the Ukrainian government and international organizations such as the IAEA to end operations at the plant. In November 2000, Ukrainian President Leonid Kuchma personally turned off the switch to Reactor No. 3 in an official ceremony, effectively shutting down the entire plant.

The need for future repairs

The sarcophagus is not an effective permanent enclosure for the destroyed reactor. Its hasty construction, in many cases conducted remotely with industrial robots, means it is aging badly, and if it collapses, another cloud of radioactive dust could be released. The sarcophagus is so badly damaged that a small earth tremor or severe winds could cause the roof to collapse. A number of plans have been discussed for building a more permanent enclosure. Most of the money donated by foreign countries and contributed by Ukraine has been squandered by inefficient distribution of construction contracts and overall management, or simply stolen.

About 95% of the fuel (about 180 tonnes) in the reactor at the time of the accident remains inside the shelter, with a total radioactivity of nearly 18 million curies (670 PBq). The radioactive material consists of core fragments, dust, and lava-like "fuel-containing materials" (FCM) that flowed through the wrecked reactor building before hardening into a ceramic form. By conservative estimates, there are at least four tons of radioactive dust inside the shelter. However, more recent estimates have strongly questioned the previously held assumptions regarding the quantity of fuel remaining in the reactor. Some estimates now place the total quantity of fuel in the reactor at only about 70% of the original fuel load, however the IAEA maintains that less than 5% of the fuel was lost due to the explosion.

Water continues to leak into the shelter, spreading radioactive materials throughout the wrecked reactor building and potentially into the surrounding groundwater. The basement of the reactor building is slowly filling with water that is contaminated with nuclear fuel and is considered high-level radioactive waste. Though repairs were undertaken to fix some of the most gaping holes that had formed in the roof, it is by no means watertight, and will only continue to deteriorate.

The sarcophagus, while not airtight, does generate a "greenhouse effect" in that it heats up much more readily than it cools down. This is contributing to rising humidity levels inside the shelter. The high humidity inside the shelter continues to erode the concrete and steel of the sarcophagus.

Further, dust is becoming an increasing problem within the shelter. Radioactive particles of varying size, most of similar consistency to ash make up a large portion of the debris inside the shelter. Convection currents compounded with increasing intrusion of outside airflow are increasingly stirring up and suspending the particles in the air inside the shelter. The installation of air filtration systems in 2001 has reduced the problem, but the problem has not been eliminated.

Consequences of further collapse

The present shelter is constructed atop the ruins of the reactor building. The two "Mamouth Beams" that support the roof of the shelter are resting upon the structurally unsound West wall of the reactor building that was damaged by the accident. If the wall of the reactor building and subsequently the roof of the shelter was to collapse tremendous amounts of radioactive dust and particles would be released directly into the atmosphere, resulting in a devastating new release of radiation into the surrounding environment.

A further threat to the shelter is the concrete slab that formed the "Upper Biological Shield" (UBS), and rested atop the reactor prior to the accident. This concrete slab was thrown upwards by the accident and now rests at approximately 15 degrees from vertical. The position of the upper bioshield is considered inherently unsafe, in that only debris is supporting it in a nearly upright position. The collapse of the bioshield would further exacerbate the dust conditions in the shelter, would probably spread some quantity of radioactive materials out of the shelter, and could damage the shelter itself.

The "sarcophagus" was never designed to last for the 100,000 years needed to contain the radioactivity found within the remains of reactor unit 4. While present designs for a new shelter anticipate a lifetime of up to 100 years, that time is miniscule compared to the lifetime of the radioactive materials within the reactor. The construction of a permanent sarcophagus that can entomb the remains of unit 4 permanently will undoubtedly present a daunting challenge to engineers for many generations to come.

The Chernobyl Fund and the Shelter Implementation Plan

The Chernobyl Shelter Fund was established in 1997 at the Denver G7 summit to fund the Shelter Implementation Fund. The Shelter Implementation Plan (SIP) calls for transforming the site into an ecologically safe condition through stabilization of the sarcophagus, followed by construction of a New Safe Confinement (NSC). The original cost estimate for the SIP was $768 million. The SIP is being managed by a consortium of Bechtel, Battelle, and Electricité de France, and conceptual design for the NSC consists of a movable arch, constructed away from the shelter to avoid high radiation, to be slid over the sarcophagus. The NSC will be the largest movable structure ever built. The NSC is expected to be completed in Early 2008.

Chernobyl in the popular consciousness

The Chernobyl accident riveted international attention. Around the world, people read the story and were profoundly affected. As a result, "Chernobyl" has entered the public consciousness in a number of different ways.

Political outcome

The Chernobyl accident was clearly a major disaster, and it received worldwide media attention. The secrecy inherent to Soviet management was blamed for both the accident and the subsequent poor response; the accident, it is argued, hastened the demise of the Soviet Union. Public awareness of the risks of nuclear power increased significantly. Organizations, both pro- and anti-nuclear, have made great efforts to sway public opinion. Casualty figures, reactor safety estimates, and estimates of the risks associated to other reactors differ greatly depending on which position is favored by the author of any given document. For example, the UN scientific committee on the effects of radiation has publicly criticized the UN office on humanitarian affairs with respect to some of its publications. The true facts of the affair are therefore rather difficult to uncover.

Chernobyl and the Bible

Because of a controversial translation of "chernobyl" as wormwood, some people believe that the Chernobyl accident was mentioned in the Bible:

And the third angel sounded, and there fell a great star from heaven, burning as it were a lamp, and it fell upon the third part of the rivers, and upon the fountains of waters; and the name of the star is called Wormwood: and the third part of the waters became wormwood; and many men died of the waters, because they were made bitter. — Revelation 8:10-11

The story appears to have spread to the West with a New York Times article by Serge Schmemann (Chernobyl Fallout: Apocalyptic Tale, July 25, 1986) in which an unnamed "prominent Russian writer" was quoted as claiming the Ukrainian word for wormwood was chernobyl.

The name of the city comes from the Ukrainian word for mugwort (Artemisia vulgaris), which is chornobyl. As a result, chornobyl has been translated by some to simply mean wormwood. This translation is a matter of controversy.

Computer virus

The CIH computer virus was popularly named "the Chernobyl virus" by many in the media, after the fact that the v1.2 variant activated on April 26 of each year: the anniversary of the Chernobyl accident. However, this is simply because of a coincidence with the virus author's birthday.

Impact on popular culture

The story of Star Trek VI: The Undiscovered Country is closely tied to the Chernobyl accident and ultimate peace between the U.S. and Russia. This was played in the Star Trek universe by the having the Klingon Empire experience a similar cataclysmic accident, and having to seek refuge with former enemies, the United Federation of Planets (humans, Vulcans and a variety of other species). This led to doubts about peace on both sides, and how those doubters attempted to destroy the developing peace.

In the 1988 film Scrooged, when the Marley-esque character visits Bill Murray's Scrooge-like character, Murray says the ghostly visitor is just "a hallucination brought on by alcohol, Russian vodka, poisoned by Chernobyl."

In a second season episode of FOX's hit show The X-Files called "The Host," Mulder and Scully encounter the famous Fluke Man, a mutated flukeworm/humanoid hybrid. The creature is later found out to have been created as a result of the Chernobyl accident.