A plume of radioactive particles extending into the stratosphere from the Fukushima Daiichi reactor complex makes a mockery of claims that Japan’s nuclear crisis isn’t comparable to the Chernobyl disaster in 1986.

The stream of nuclear contaminants are being driven by an intense heat source consistent with exposed fuel rods burning in air, the process that inevitably leads to meltdown unless massive and prompt intervention is successful.

These radioactive clouds are now mixing with higher altitude air currents and being dispersed more widely across northern Asia and the north Pacific.

They are being tracked by the international Volcanic Ash Advisory Centre in London, which is authorised by the International Atomic Energy Agency to alert airlines and airports to accidental releases of nuclear contamination.

The VAAC this morning issued 10 nuclear emergency flight information regional advisories (FIRs) to enable airlines to route flights well clear of the hazard along air corridors across northern Asia, southern China including Hong Kong,  all of Japan and Korea and the high latitude or sub-polar routes that are used to connect North America to dozens of Asia-Pacific cities.

Qantas either has or will soon re-route its Narita  flights to achieve a minimum time turnaround at the main Tokyo airport and return via Hong Kong, where there will be a crew change.

This change will avoid overnight stops by crews in Japan for occupational health and logistical reasons, but the airline is closely monitoring the changing situation and all travellers (and on all airlines) are advised to check for late changes to the northern Asia flights.

There is a line of six nuclear reactors at the Fukushima plant, four of which have now experienced one or more large explosions with the remaining two that had been taken off line before the earthquake and tsunami of last Friday now heating up to levels so dangerous Tokyo Electric is considering breaking down the reactor block walls to allow a build-up of hydrogen gas to escape.

Exasperation with the quality of information coming out of the Japanese nuclear authority, the government and the Tokyo Electric company led to harsh words from the French nuclear authority this morning.

It said  the Daiichi accident could be classed as a level 6 event on the scale of one to 7. The Chernobyl calamity in 1986 began as a level 6 event and was then elevated to level 7, which until now consist of the only level 6 and level 7 events recorded.

An official was quoted as saying “Tokyo has all but lost control over the situation”.

This morning the Japan nuclear authority insisted that level 4, an event with purely local effects, was the appropriate level,  which is clearly not what the normally ultra-tactful International Atomic Energy Agency thought when it directed the VAAC to issue the warnings to airlines, and also to the airports at which any aircraft exposed to radiation must be thoroughly decontaminated under international conventions.

The major European and China  flag carriers have variously cancelled services to Japan or re-routed flights to ensure that flight crew do not overnight in Tokyo, similar to the action that Qantas is about to take.

The quality of information from the Japanese has descended into farce, with simultaneous claims that  radiation levels are harmful  in the Chernobyl-sized exclusion zone but did not constitute a threat to health. This follows the patently dishonest misuse of radiation exposure metrics used for the first 3½ days of the crisis, which understated the real levels by 1000 or three orders of magnitude.

The US think tank, the Institute for Science and International Security, said the situation at Daiichi had worsened considerably and was now closer to a level 6 event and “may unfortunately reach a level 7”.