Friday morning update.... it's Earth Day

Plant data from Fukushima Daiichi remains fairly constant, with the reactor plants showing continued slow cooling. In fact, it's been released that the latest NRC consideration of the situation is that it is "stable, but fragile." This of course refers to both the potential for either loss of cooling to the cores, or else further possibly sudden release of contamination to the environment, which most likely would be a release of contaminated water.

TEPCO continues to pump water out of No. 2 plant, as reported everywhere, and intends to double pumping capacity within about a week.

As Earth Day 2011 progresses, we also find in the headlines in Japan the stories that the remaining reactor plants at Kashiwazaki Kariwa, the largest nuclear generating station in the world, will not be allowed to restart until the Fukushima situation is resolved (being stopped apparently by local government) and we also see the hint that Fukushima Daini will not be allowed to restart until certain safety guarantees are made (this stoppage by the prefecture's governor.) TEPCO certainly has its hands full, and will be very short of power come the summer if all of these reactor plants are kept shut down.

Having said that, it is of course imperative, given Fukushima Daini's closeness to the now highly-active earthquake zone off the northeast coast, that TEPCO perform major modifications to the plants at that site and improve tsunami protection before those plants can be allowed to restart. The case against idle reactors at Kashiwazaki Kariwa, where some reactors have never shut down (there are seven on site) is much less easy to make considering that it's on the opposite coast.

Also, given that it's Earth Day, we might expect a horde of articles to appear today against nuclear energy in the United States. The more informed authors might target boiling water reactors. However, it's important to note the modifications and alterations made to all US BWR plants that use Mark I containments, as delineated by the NRC site and given some analysis by your author:

1. In 1979, backup safety systems were separated. This means that backup systems like diesel generators were made fully and totally independent in all aspects. This might include ensuring completely separate water cooling for the diesels, it might include totally separate buses the diesels power, and even separated locations. What this step did was eliminate the chances that a problem in one backup safety system could have a negative effect on the operability of another.

2. In 1980, control rooms were reconfigured to improve operability and analysis of information by plant operators.

3. In 1980, the suppression chambers were strengthened. It had been recognized that the strength of the torus section of the Mark I containment could be considered a weak point of the design, regarding ability to hold structural integrity against severe accidents and a backfitting / rebuilding program was performed to strengthen this portion of the physical containment. (This might have helped Fukushima Daiichi No. 2, whose suppression chamber is damaged.)

4. In 1988, more batteries were added at all stations to protect against SBO or Station Blackout. As readers here now know, longer battery life delays core damage if there are no sources of AC or DC available either offsite or from EDG power.

5. In 1992, vents were added to vent the primary containment directly to atmosphere if necessary. These vent pipes, with valves in the vent path to maintain primary containment integrity while still allowing a direct vent path through a high point stack if necessary, are intended to vent hydrogen directly to atmosphere instead of allowing it to build up inside the primary and possibly leak to spaces in the reactor building. (This might have aided No. 1, 2 and 3 plants at Fukushima Daiichi.)

6. In 2002, plants added another spare portable diesel generator and water pump. The need for this is obvious, given the events at Fukushima Daiichi. These have been present at US plants now for a number of years.

We can see then that there are many things that might be considered superior points in the construction and operation of US BWR plants as compared to those at Fukushima Daiichi, and in fact these are just a few of the differences. The nuclear power establishment in this country has learned from past accidents and incidents, and many many reactor-years of operation in a number of programs. We need to all keep this in mind as Earth Day 2011 progresses, and the environmental voices begin to rise in volume.

Just six months ago, nuclear energy was one of the darlings of the green movement and environmentalists and climatologists in many places the world over. We must thus also remember that what's happening in Japan is the 'worst case' scenario, in which a major natural disaster overwhelms all active and passive core safety protections. Knowing the differences here in the USA compared with Japan, we can.. and should.. rest very comfortably at night.

10:00 AM Eastern Friday 4/22
ATOMIC POWER REVIEW