how was blamed ater chernobyl event occur

As an AI language model, I don't have personal opinions or emotions but here is a brief answer to your question.

The blame for the Chernobyl event primarily falls on human error and design flaws of the RBMK nuclear reactor. The reactor was undergoing a safety test when the operators made a fatal mistake that caused a steam explosion and subsequent fire. The test should have been conducted during maintenance shutdown of the plant but the reactor was still operational, which was a significant oversight.

Furthermore, the design of the reactor was inherently unstable, which made it prone to accidents. The plant's management and Soviet government also failed to implement adequate safety measures and protocols.

The operators and engineers directly involved in the test were held responsible and faced legal consequences for their actions. The Soviet government also took steps to improve nuclear safety in the aftermath of the disaster.