Japan: Videotape from 1995 Monju reactor leak

The infamous Monju fast-breeder reactor leak of 1995, an accident that long ago earned itself a place in the history of nuclear power in Japan, has returned one more time to haunt government and industry officials with images they had hoped they would never see again.

Named after the Buddhist divinity of wisdom, Monju, located in Japan's Fukui prefecture, is Japan's only fast-breeder reactor. Unlike conventional reactors, fast-breeder reactors, which “breed” plutonium, use sodium rather than water as a coolant. This type of coolant creates a potentially hazardous situation as sodium is highly corrosive and reacts violently with both water and air.

On December 8th, 1995, 700 kg of molten sodium leaked from the secondary cooling circuit of the Monju reactor, resulting in a fire that made headlines across the country. Although the accident itself did not result in a radiation leak, many argue that the sodium spill itself came very close to detonating Monju, a catastrophe which would have spilled plutonium into the environment.

Following the fire, officials at the government-owned Power Reactor and Nuclear Fuel Development Corporation (PNC), operators of Monju, first played down the extent of damage at the reactor and denied the existence of a videotape showing the sodium spill. Later, they released still shots only, showing things like intact pipes and clean floors and claiming that there had only been “a minor leakage in the secondary sodium loop [that had] caused some fumes”. While short videos were released, these were edited to hide the full extent of the damage. Further complicating the story, the deputy general manager of the general affairs department at the PNC, Shigeo Nishimura, 49, jumped to his death the day after a news conference where he and other officials revealed the extent of the cover-up.

Starting from September of last year, Nishimura's family brought the story back to light in a trial against the PNC at Japan's High Court. It is in this context that a never-before-seen video (the so-called “2 o'clock video”), described in a 1996 New York Times article as “show[ing] men in silver space suits exploring the room in which sodium compounds hung from the air ducts like icicles”, has finally come out, released on YouTube by a group called News for the People in Japan (NPJ) and also posted by blogger tokyodo-2005 at his blog. Japanese subtitles have been translated to English and posted at dotSUB, as well as embedded in this article below.

The opening lines in the video provide some background:

「動燃が隠したもんじゅナトリウム漏れ事故直後の映像 いわゆる2時ビデオ」

Video taken just after the sodium leak accident at Monju, hidden by the PNC – the so-called 2 o'clock video
Just after the accident, the PNC sent employees to the site to film the leak.
However, due to the graphic nature of the footage, the PNC hid it.
The PNC explained that they hid it because “it has no value”.


With your own eyes, we want you to judge why the PNC hid the video.
This video was not only hidden at Monju (Fukui Prefecture), it was also discovered later that there was another copy hidden at the head office.
An employee who had to lie at the press conference committed suicide right afterwards.
What was it that drove him to commit suicide… Think about this.

Snapshot from Monju leak video

Snapshot from video showing pile of sodium under the leak.

In his blog entry, tokyodo-2005 goes into more detail about the video:


A trial hearing for the case was held the other day, and two major facts were claimed by Nishimura's side.



One is the truth of the “2-o'clock video”, about which the PNC had to keep lying.



A small mountain of leaked sodium is clearly captured [in the video], and it seems obvious why the PNC wanted to hide it. Because this was hidden, they had no choice but to keep telling lies one after another, and as these lies were revealed, voices demanding the closure of the reactor grew louder. At the court hearing, the truth of the video — the video which became the core of the lies, and which the PNC had no choice but to hide — was revealed.

Snapshot from Monju leak video showing pile of sodium

Snapshot from video showing pile of sodium

事故が起きたのは、平成7年12月8日、ビデオが撮影されたのはそれから6時間後の9日午前2時、ダビングされたビデオが本 社に持ち込まれたのがその日の午後9時半。居合わせた社員はこれを視聴している。

The accident happened on December 8, 1995, and the video was filmed 6 hours later at 2 a.m. on December 9. A copy of the video was brought to the head office on the same day at 9:30 p.m. All the employees present watched this video.



Here, Nishimura was supposed to say that they found out about the 2-o'clock video having been brought to the head office on December 25, but instead for some reason he said it happened on January 10.[…]



Nishimura must have no choice but to silence his own tongue. As in the will mentioned at the beginning of this entry, he made it out so that everything was his mistake when he committed suicide.


Monju is soon going to be reopened. Has their habit of covering up — which pushed Nishimura to suidide — been improved? At least, I don't seen [any evidence of an] attitude of attempting to reveal everything in court and reflect on what happened…. Nishimura might have saved Monju with his death, but I don't think he would want any other victims to follow his path.

More information about the re-opening of Monju can be found in this article at World Nuclear News.

[This article was co-written by Hanako Tokita.]

[Update (Jan. 28): More background to the trial mentioned in the article in this 2004 Japan Times article.]


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