Reactor Containment & Fuel Storage from UCS; (h/t commenter lobster)

Update: Monday 5:30 pm (EDT): AP reports utility officials say some of the pumps in Unit 2 are damaged and must be replaced. They’re on order.

It’s Monday morning in the US; it’s Monday evening in Japan.

Quick Summary: Over the weekend, hopes of getting the reactors and spent fuel storage pools cooled rose significantly at the Fukushima Daiichi Nuclear Station, although on Monday, new smoke rose from Unit 3 (see NYT photo) forcing another evacuation there. They’re not sure whether there was another explosion (none was heard) nor do they know the source/cause of the smoke.

Rising hopes are attributed to getting power connected to some Units, though cooling systems have not yet been restated, and their improving ability to target sea water spray into the spent fuel storage pools and sustain it for several hours. This appears to be lowering temperatures at the critical hot spots.

In the meantime, they’re finding higher radation levels in surrounding communities, creating concerns about milk, local produce and tap water.

Power to the Units. Over the weekend, plant officials were able to complete laying transmission cables to transmit electric power from the grid to Units 1 and 2; they’re now completing connections to Units 3 and 4. There are reports they were able to connect to terminal/hubs providing power to a central control room between Units 1 and 2.

As of 8:30 am Monday (EDT), they have not attempted to turn on the cooling systems at Units 1 and 2. They’re still testing gauges, water temps, and other equipment to determine water levels and temperatures, and thus which pumping/cooling equipment needs to be tested for restarting. So even though they have power, the normal cooling systems are not yet functioning and we don’t yet know what equipment will work.

As we feared, the New York Times reports this morning (EDT) that workers are finding critical equipment, including a ventilation system, that must be repaired before they can restart the cooling systems at Unit 2. Recall that all four units suffered explosions, but Unit 2 suffered minimal exterior wall/roof collapse, whereas Units 1, 3, and 4 were extensively damaged.

After connecting the transmission line on Sunday, engineers found on Monday that they still did not have enough power to fully run the systems that control the temperature and pressure in the building that houses the reactor, officials from the nuclear safety agency said.

Engineers were also trying to repair the ventilation system in the control room that is used to monitor conditions in the No. 1 and No. 2 units. When that work is completed, possibly on Monday, it will allow the power company, also known as Tepco, to begin cleansing the air in the control room so that workers can eventually re-enter and begin using equipment inside to monitor conditions in the two reactor units.

At the same time, they’ve restored back-up generation at Units 5 and 6. With restored cooling functions, those two reactors and their spent fuel storage pools are out of danger, at least for the moment.

Continued spraying of sea water at Units 3 and 4. With the normal cooling functions still unavailable at units 1-4, they’ve continued spraying water from high-pressure fire hoses. They’ve brought in more crews and equipment, including a large crane that pictures show getting a hose above a reactor building and focusing spray down towards the fourth floor spent fuel pools. The ability to do this remotely (thus limited worker exposure next to the reactor) and to continue for several hours at a time has greatly increased their ability to inject water into the reactor buildings.

On Sunday, there was a report they had determined the spent pool fuel at Unit 4 was full. What accounts for this? Recall that last week, US Nuclear Regulatory Commission officials disagreed with the Japanese by insisting that Unit 4′s spent fuel pool was dry — all the water had either evaporated from the rising heat/boiling (which meant uncovering and damage to fuel and fuel cladding) or had leaked from cracks to the pool walls or floor. [One NHK TV segment interviewed a plant worker who, at the time of the quake, was near one of the pools; he and others were splashed with water as the quake sloshed the storage pool water.] The US claim led to a hypothesis by Union of Concerned Scientists that pool water could also have escaped through a breach in the “gate” that allows transfer of fuel assemblies between the reactor core and the spent fuel pool. [See my previous update].

Now, however, plant officials are claiming the Unit 4 spent fuel pool is full. If true, was it ever damaged or dry? Or is this simply the result of continuing efforts to spray sea water into the pool? Whatever, it’s a good sign that sufficient water is there and temperatures have fallen.

One issue we touched on early last week but haven’t heard much about lately is the corrosive effect of sea water on containment structures and pumping equipment. Remember that the decision to start injecting sea water was interpreted at the time as a decision to give up on any hope of saving the plant for future operation, since the sea water would over time destroy critical equipment. But it was necessary given the need to prevent a wider meltdown and public health hazard.

They have now spent over a week pumping sea water into units 1-4 (and Units 5-6?), both into the cooling systems circulating through the reactors and into the spent fuel storage pools. When does that necessary emergency action become the corrosion that causes the next system breakdown, even if they are able to restore pumps and other cooling mechanisms? And what will they do to prevent this inevitable breakdown?

Increasing concern about area radiation and public health. Dozens of plant workers have now received dangerous levels of radiation, possibly lethal for many of the “Fukushima 50″ who stayed at the plant when others were evacuated. They’ve continued to cycle in new workers, particularly those who can operate the fire trucks and other sea water pumping equipment.

Yesterday, various radiation monitoring systems near Fukushima and another plant were reporting spikes in radiation readings, but it’s unclear what caused this. Another event at Fukushima? Another plant? Rain? Commenter lobster was tracking last night.

Over the weekend, there were reports of officials finding unsafe radiation levels in milk and increased levels in local produce, first spinach and now other foods grown in Fukushima and neighboring prefectures. There is a ban on exporting produce from these areas, and they are continuing to monitor for food contamination. Also, there is warning against drinking tap water in a community about 30 miles away. That signals a spreading public health problem. As of Monday, more than 29,000 people have been evaculated from the area.

The NHK live tv feed (English) has been showing frequent updates on radiation levels at various locations, comparisons with normal exposure levels and recommended precautions.

And it’s been raining in northern Japan. So, for people still there, it’s stay indoors, don’t go out in the rain, avoid contaminated produce and wash everything.

More updates as warranted.

Sources:
NHK World TV

New York Times, New Repairs Delay Work at Crippled Nuclear Plant

New York Times, Status of Each Unit, with timelines

Breakthrough Institute, Situation Report

Union of Concerned Scientists, All Things Nuclear; and Daily Briefings

Radiation dose chart (please note disclaimers)