No. It was not the lack of interlocks. It was the basic design of the reactor. It is nothing like Western reactors - part of it being designed to use hundreds and hundreds of small pipes, able to be welded by pretty well any old welder, instead of properly coded welders for the job. The design was known to a) increase power output as the control rods were inserted, b) take too long to insert the rods and c) a single failure could cause damage to nearby channels, defeating the concept of being safe with two failures (Western licensing would have required more anyway).
Plus the Soviet Union did not even require any containment around the reactor.
They knew it was unsafe, but did nothing about it. After Chernobyl, they did make some changes to improve safety - making the basic design safer. Changes that they could have done years earlier, but no-one dared to speak out against higher power.
UK companies in the nuclear industry have a policy that anyone - no matter if they a Nuclear Safety Engineer or a humble labourer, can stop any job at any time if they think that there is danger ... even if that job is nothing to do with them, but they are just passing by and see something.
At the time it took place, it was not authorised at higher levels IIRC, only locally and the test began despite being far outside the parameters stated as required for the test and well into the danger zone - so it
*was* unauthorised.As an example of the differences here. To change a single set-point requires access via a password or key protected control; which in turn requires documentation declaring what change is proposed, the reason for it, potential consequences, etc., which is then assessed by multiple disciplines onsite, in offsite design offices and possibly by the ONR to ascertain the effects of the change. Only then would it be authorised and actioned - with a full update of all the existing, relevant documentation. Then when changed, the change would need to be observed, checked and recorded.
60 years ago, things would have been different, but these days everything is *very* tightly controlled.