Skip to comments.Japan:N-reactor cooling failed before tsunami
Posted on 05/18/2011 7:26:07 AM PDT by TigerLikesRooster
N-reactor cooling failed before tsunami
The Yomiuri Shimbun
An emergency cooling system of the No. 1 reactor at the Fukushima No. 1 nuclear power plant malfunctioned after the March 11 earthquake and before the tsunami hit, data released by plant operator Tokyo Electric Power Co. have revealed.
According to a large cache of data concerning plant operations from March 11 to 14 released Monday by TEPCO, the No. 1 reactor's isolation condenser, which operates on direct-current power, began to malfunction shortly after the Great East Japan Earthquake struck the Tohoku and Kanto regions.
According to the data, the No. 1 reactor was put into emergency shutdown immediately after the earthquake when control rods were inserted into the reactor core. The isolation condenser was then automatically activated at 2:52 p.m., initiating cooling and pressure reduction inside the reactor.
However, around 3 p.m., only about 10 minutes after it began operating, the isolation condenser stopped functioning temporarily, and then went on and off intermittently as valves between the condenser and the pressure containment vessel were opened and closed, according to operation records.
According to TEPCO, the pressure within the reactor fluctuated violently immediately after the earthquake. The cause of these fluctuations is not known, but TEPCO suspects workers manually suspended the condenser to stabilize the pressure.
(Excerpt) Read more at yomiuri.co.jp ...
“TEPCO suspects workers manually suspended the condenser to stabilize the pressure.”
What the heck does that mean, in the context of N-plant operations? Isolated the condenser (valved it off)? Something else entirely?
My guess, leaving fully competent opinion for others, is that the earthquake mechanically damaged the reactor core.
I just can’t see an alternative with the cooling condenser being shut off due to massive containment pressure changes ten minutes after the neutron absorbing shutoff rods were inserted. If the core were undamaged the shutdown process would have proceeded at that point in time as it had in previous emergency shutdown safety drills, that is, “normally”. It is as if the core fuel element tubes had changed their effective surface area and/or separation distance, or that the neutron flux absorber rods did not insert properly.
One hopes someone with more background than I will satisfy my curiosity -