The Wall Street Journal ran an article yesterday that revealed new details of the timeline for the earthquake and tsunami. One interesting detail had to do with the high-pressure coolant-injection system (HPCI), which provides emergency cooling water in the event of a loss-of-power accident:
The HPCI pumps in emergency water from tanks, such as the suppression pool, and injects water into the reactor. The system can operate without electricity because it uses steam from the reactor to power the pumps.
However, Tokyo Electric Power (TEPCO) now thinks that the HPCI may not have functioned as designed due to damage from the earthquake:
The latest questions surrounding the quake’s impact were prompted by data, released Tuesday, showing a sudden plunge March 12 in the pressure inside unit No. 3’s reactor. The sharp drop occurred after workers activated an emergency cooling mechanism known as a high-pressure coolant-injection system, or HPCI, to prevent the overheating of the reactor core.
The pressure plunge prompted speculation that there may have been a rupture in the pipe used for the coolant-injection operation, possibly as a result of the earthquake.
The Nuclear Regulatory Commission needs to assess US nukes in light of earthquake damage and the experience at Fukushima. It now appears that the earthquake alone was sufficient to knock out both offsite power and damage the primary emergency cooling systems.
Here’s a link to the article: http://online.wsj.com/article/SB10001424052702304066504576344633513692862.html