Fukushima Daiishi Nuclear Plant update March 18, about 8 PM Tokyo time. 
Taken from NHK World English. and other sources as cited. 

Japan Self-Defence Force photograph dated March 16 of Reactor 3 damage
 

The New York Times is reporting that Japan has raised its assessment of the severity of the crisis. Until now, they rated it a 4 on the 7 level international scale of nuclear accidents. It has been increased to a 5. What does this mean? They now admit this accident is no longer of local significance. For comparison, the Three Mile Island incident was rated as a 5 on this scale and Chernobyl topped it out at a 7.

It is now acknowledged that the spent fuel pool at reactor 4 is damaged and leaking, a possibility raised in this blog earlier this week, making it very difficult or impossible to refill the pool with water.

Efforts to spray water on reactor 3, the most dangerous of the six reactors at the site, continue.
Seven fire trucks are now spraying that reactor.

One truck is beginning to spray the reactor 1 spent fuel tank as the water level is falling to a dangerous level.

Reactor 2 continues to emit steam, indicating that the pool water level is too low or, that the spent rods have gotten too hot.

Reactors 5 and 6 spent fuel tank temperature are rising now and the situation is being monitored. But they are not deemed an immediate threat.

It is said that TEPCO has restored electric power to the plant complex but there is no word if they have successfully restored the cooling pumps to service. It is unknown if the pumps were damaged by the tsunami, the earthquake or the various explosions at the site and if some or all of the pumps even can be restored to service.

Many people in the areas most affected by the earthquake are reporting various illnesses related to lack of heat and food. It is unknown if these illnesses are related to exposure to radiation.

It must be remembered that these efforts to apply water to the spent fuel pools have no relation to, or effect on, any possible partial or full meltdowns of fuel in the reactors themselves.

RTT News reported that International Atomic Energy Agency (IAEA) chief Yukiya Amano has arrived in Tokyo to confer with Japan's Foreign Minister Takeaki Matsumoto about the crisis. Amano stated that Japanes authorities have agreed to provide a transparent account of events. I take that to mean that they have not provided a transparent account heretofore.

After his meeting with Japan's Prime Minister Naoto Kan, Amano said this about the battle to stabilize the nuclear plants. "This is a very grave and serious accident so it is important that the international community, including the IAEA, handles this jointly. Especially cooling (the reactors) is extremely important, so I think it is a race against time."

TEPCO now states that an outside power source has been brought to the plant but that they have not yet successfully connected that power to the cooling systems (the suppression pumps) of the plants. It is unknown what systems will even function once electricity has been supplied. TEPCO states that this effort is hampered by very high radiation levels in the work area. It is hoped that the suppression pump for plant 2 can be put back in service Saturday. The high levels of radiation is the biggest problem facing workers attempting to repair the inoperative cooling systems.

The IAEA reported in its website that Japan on Thursday night at 9:15 PM EDT (Friday morning Japan time),  altered the INES (The International Nuclear and Radiological Event Scale) ratings of the events at Fukushima Daiishi  as follows:
Core damage reactors 2&3  -Rating 5
Loss of cooling water of spent fuel pool at reactor 4  -Rating 5
Loss of cooling functions at reactors 1,2, &4    -Rating 3

Most of the control functions of the reactor have been made inoperable due to the fact that they were submerged in seawater during the tsunami. Workers are limited to working only 20 minutes at a time in the control rooms of the reactors. The highest radiation is in reactors 3&4. That is the reason it takes three days to restore power to the cooling functions of each reactor. Control functions must be replaced. It will  not be known if the suppression pumps have been damaged until they are actually used. Or if they can be fixed or need to be replaced.