Operator error
In the process of preparing and conducting the experiment operations personnel were several irregularities and errors, some of which had no impact, part - predetermined disaster. Immediately after the accident, it is possible to assign almost the entire responsibility for the crash of personnel involved in the experiment, but starting at the end of 1986 were recorded and data on the above unsatisfactory properties of the RBMK. In addition to violations of conditions of normal operation, turn off the elements of the security breach and technological procedures (ie, violations of the document "top level" for nuclear power plants - production schedules), notes and keeping a dangerous process, which can be described as work "on the brink of a foul."
So, initially it was noted that operational staff admitted following the most significant violations:
Reduced operational reactivity margin significantly below the allowable value;
The failure of the reactor power substantially below the planned program;
Inclusion in the work of all the main circulation pumps (MCP) with increased flow through the MCP above regular technical significance;
Lock the shielding of the reactor at a signal stop two turbochargers;
Lock protection on the water level in drum-separators (BS);
Lock protection on the vapor pressure in the BS;
Turn off emergency cooling system.
When working on INSAG-1 IAEA experts, examined the material provided by the Soviet side, and based on oral statements by Soviet specialists (a delegation of Soviet specialists headed Legasov VA, which was not a specialist in reactor plants), expanded the list of violations, expanding its , including unconfirmed documented violations.
In 1991, the Commission GAN, headed by a former employee of Chernobyl Steinberg and included, mostly former employees of the Chernobyl nuclear power plant, has revised some questions about irregularities in the staff noted in INSAG-1. As mentioned above, this work has been included as an attachment in INSAG-7, and is known as the report of the commission Steinberg. According to the commission Steinberg certain violations attributed to the staff, were either not established or could affect the development of the accident:
Simultaneous operation of eight MCP, lock protection on the stop signal two TG do not interfere in effect at the time of the accident instruction. Excess flow through the MCP was confirmed, but it was noted that it did not lead to their failure (so-called cavitation breakdown).
Protection of the pressure in the DS is not disabled, was changed setting its activation (one of the two setpoints can be selected by the operator)
Lock the emergency cooling system (not influenced the course of the accident).
It was confirmed that disabling the protection of the water level in RBCs was a violation, but, according to the commission, it did not affect the development of the accident.
In addition, the commission headed by Steinberg, said that the value of the ISP is not excreted quickly in the MCR. It was necessary to carry out several operations to calculate and get this option, so operational staff can not fail to notice in time to decrease below the permitted values. Noted by the Commission and that the project did not include the ISP as a parameter, which must be provided "security system, not to mention the emergency protection in achieving this parameter limits.
In addition, the commission's view Steinberg, technological protection (in terms of the drum-separators, and others) should not be regarded as unrelated to the reactor directly: "Operations with the values of settings and disabling technological protection and blocking caused or contributed to the accident did not affect its scale. These acts had no relation to emergency protection of the reactor itself (in terms of power, the rate of growth), which staff were not deduced from the work.
Also in the report INSAG-7 was included the commission's report, which included staff VNIIAES and History, Institute of Atomic Energy and other organizations (INSAG-7, it is positioned as a commission, headed by the Director VNIIAES Agobyanom). This report is aimed primarily at the technical aspects of the accident, unlike the commission Steinberg, contains no analysis of the actions of operating personnel. Nevertheless, this report points to the following examples of dangerous work:
Poor, with a modern point of view, the regulation of safety measures in the test program;
High flow coolant through the reactor at low flow rate of feed water, which led to a small subcooling coolant to the boiling temperature at the entrance to the active zone and a low steam content in the core. Commission states that both these factors directly affect the scale has shown in tests effects.
Thus, the most significant errors operational staff should be called:
Interpretation of the alleged test as electric;
Inadequate training programs * tests, including the regulation of safety measures;
Significant deviations from the program in preparation for the experiment and its holding;
Disable security systems, including emergency protection of reactor;
Breach of the normal operation of the reactor in the preparation and conduct of the experiment;
Conducting an experiment on nezaglushennom reactor, located in nereglamentnom condition;