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CONTRIBUTION · 13th March 2011
World-Nuclear-News dot org
Efforts to manage Fukushima Daiichi 3

(Thanks to Jupiter for providing this source of quality information)

13 March 2011

FIRST PUBLISHED: 4.03am GMT

UPDATE 1: 9.35am GMT. Information on seawater injection

UPDATE 2: 1.30pm GMT. Issues related to seawater injection, Change of headline from Venting Fukushima Daiichi 3


Operations to relieve pressure in the containment of Fukushima Daiichi 3 have taken place after the failure of a core coolant system. Seawater is being injected to make certain of core cooling, but two separate malfunctions are hampering efforts.

READ MORE AND GET THE ONGOING AND LATEST UPDATES HERE.

The news comes one day after the plant's first reactor was effectively written off as a result of a hydrogen explosion and the move to inject seawater to make certain of cooling the reactor core. Two days ago were the earthquake and tsunami that have proven Japan's worst ever natural disaster.

Now Tepco has reported it has not been able to restart unit 3's high pressure injection system after an automatic stop. This left the reactor without sufficient coolant and obligated Tepco to notify government of an emergency situation.

Preparations for potential pressure relief had already been underway for many hours and Tepco manually vented the containment between 8.41am and 9.20am on March 13.

Noriyuki Shikata, director of global communications in the prime minister's office, said the venting operation was expected to cool the containment, noting that "minute quantities of radioactive materials are released." When this occurred at unit 1, the International Atomic Energy Agency said the emission would be filtered to retain radioactive materials within the containment.

Status of water injection

Injection of fresh water mixed with boron to inhibit nuclear reactions was started as soon as venting had been completed. However, water levels continued to fall and Tepco began an operation to inject seawater into the reactor vessel.

In a media briefing at 8.00pm, chief cabinet secretary Yukio Edano stated that while initially the water level had risen, a gauge indicated that this had leveled off, despite ongoing seawater injection.

The Japan Atomic Industry Forum (JAIF) said that a malfunctioning guage means that water levels cannot be confirmed. Meanwhile, pressure in unit 3 has been gradually rising and this would need to be relieved, Edano said, warning that the vent valve in unit three was showing signs of failure and this was interfering with Tepco's efforts.

Measurements around the unit had not detected increased radiation levels. A twenty kilometer evacuation order is in effect and some 200,000 people have been moved from their homes so far.