Versions of the causes of the accident
At various times, been various versions for reasons of the Chernobyl accident. Experts offered different hypotheses that led to a jump in power. Among the reasons referred to as: the so-called "breakdown" of the circulation pump (violation of their work as a result of cavitation), by exceeding the permissible flow, pipe break large cross-section and others. Also reviewed various scenarios of how specifically developed processes that led to the destruction of the reactor after the jump power, and what happened with the fuel after that. Some versions have been refuted by studies in the following years, others remain valid until now. While there is consensus among experts on the major causes of the accident, some details still remain unclear. The importance of these components is caused estimates ejected during the accident, fuel and radioactive materials into the environment, and consequently, scope of work necessary to eliminate the accident (for example, the construction of the Shelter-2 "). Examination of the causes is complicated, and certain moral aspect: as indicated INSAG, the catastrophe has become possible due to poor safety culture of all organizations of the Soviet Union involved in the nuclear industry, including operating, supervisory, organizations that have developed a reactor and nuclear power plants, as well as organizations that support nuclear power plant operation . Thus, to judge the causes and consequences of the accident have professionals whose organizations (due to the recognition of low safety culture) directly or indirectly bear some responsibility for the accident.
It is quite interesting is the discussion of the root cause of accidental dispersal. Been expressed more than one version:
Cavitation MCP, which triggered off MCP and the intensification of process of steam with the introduction of positive reactivity;
Cavitation in the SAM, which caused supply additional steam in the core with the introduction of positive reactivity;
Disable the MCP to protect themselves, giving rise to an intensification of process of steam with the introduction of positive reactivity;
Firing the emergency protection, caused the introduction of positive reactivity;
The version of the cavitation fluid to the SAM is based on numerical studies, showed that the coolant temperature at the reactor inlet, slightly different from the boiling point (which was done by personnel working at low capacity and excess consumption of coolant through the reactor) may podkipanie coolant in the grooves SAM, and the resulting vapor, drawn coolant flow, could fall into the active zone, substantially changing the field of energy in the most dangerous period of the accident.
Cavitation or deactivate the MCP for self-defense would lead to rapid reductions in coolant flow through the reactor, which, given a suitable front over hot water (owing to the actual cessation of feeding the reactor with water shortly before the accident), could lead to intense vaporization in the reactor core, which provided a "primer "accidental dispersal.
There are suggestions that the explosion is the result of sabotage, for whatever reason, hidden by the authorities. Proponents of this theory, in particular, mention that the destroyed unit was photographed by U.S. satellite, which in their view, was too accurate and at the right time at the desired orbit around the Chernobyl NPP. Like any "conspiracy theory", this version is difficult to disprove, because any evidence that it does not fit, be declared fraudulent. The accident was torn down by the secret object of Chernobyl-2 or the-horizon radar Arc-1 (the object was put out of action due to proximity to nuclear power plants and high levels of radiation after the accident).
Another theory that has received wide recognition, explains the accident local earthquake. The justification cited by earthquake shock, which was fixed at approximately the time of the accident. Supporters of this version claim that the impetus has been registered before, but not at the time of the explosion (this claim is disputed), and strong vibration, which preceded the crash could be caused not by the processes inside the reactor, and earthquake. The reason that the adjacent third block was not injured, they consider the fact that the tests were conducted only on unit 4. Employees of NPP, were on other blocks, no vibration is not felt.
There is a theory that the cause of accidental dispersal click of a button AZ-5 and the beginning of the introduction of control rod and the protection of the active zone. It is stated that in this case one reactivity introduced by the end effect would be enough for emergency dispersal and destruction of a reactor. . Direct calculations denied such developments. However, additional calculations, with the original data, fitted to the worst case, showed the principal feasibility of such a scenario.
According to the version proposed by KP Checherov, the explosion was nuclear in nature. Moreover, the main energy of the explosion is not freed in the pit of the reactor, and in the space of the reactor hall, where the active zone, together with the lid of the reactor was raised by his assumption of reactive power created by steam escaping from the broken channels. This was followed by a nuclear explosion and the subsequent drop in the reactor lid on mine reactor. The ensuing as a result of this attack was interpreted by eyewitnesses as the second explosion. This version has been proposed to explain the lack of fuel inside the "sarcophagus". According to post-accident investigations in the shaft reactor, podreaktornyh and other premises were found not more than 10% of nuclear fuel that was in a reactor. It was found many pieces of zirconium tubes several centimeters long with characteristic lesions - as if they were torn from the inside. However, it is believed that inside the sarcophagus is about 95% of fuel.
Notable among these versions is the version presented by staff Interdisciplinary Scientific-Technical Center "Shelter" National Academy of Sciences of Ukraine, BI Gorbachev. According to this version, the explosion occurred due to the fact that the operators during the lifting power after the failure of learned too many control rods and blocked emergency protection, which prevents them from quickly raise output. At the same time they allegedly failed to notice that the power started to grow, which eventually led to the crackdown prompt reactor.
According to the BI Gorbachev, in regard to the primary source of data used for analysis of all the technical experts, the fraud was committed (in this case he selectively uses these data). And he believes that in fact the chronology and sequence of events of the accident were different. For example, in his chronology of the reactor explosion occurred in 25-30 seconds before pressing the emergency protection (EP-5), but not after 6-10 seconds, according to all the others. Pressing the button AZ-5 BI Gorbachev, combines the accuracy of the second explosion, which transferred them to do so by 10 seconds ago. According to him, this second explosion was the explosion of hydrogen, and it is registered by seismic stations as a weak earthquake.
According to opponents of BI Gorbachev, his version contains inconsistencies, is inconsistent with the physics of processes occurring in a nuclear reactor, and contrary to the recorded facts. On it was repeatedly pointed out, however version is widely used on the Internet.
According to another version, the cause of the explosion could be the artificial fireball that occurred during the electrical tests in 1:23:04, which has penetrated into the reactor core and led him out of the ordinary mode. The author's conjecture asserts that he was able to establish the nature of ball lightning and explain many of its mysterious properties, in particular, the ability to move with great speed. He argues that the fireball could have arisen in a split second to get into steam in the reactor core.