Reactor 3 – essentially the same ECCS pipe valve failures as the rest.

http://fukushima.ans.org/report/accident-analysis

American Nuclear Society Fukushima Diiachi ANS report

II.B.3. Fukushima Daiichi Unit 3
The situation at Unit 3 followed closely that of Unit 2, except that the RCIC system ran for only 20+ hours. However, the DC power supply for the HPCI system was not damaged, so the HPCI system started up and was run for an additional 15 hours. The operation of the HPCI system apparently also had the side benefit of reducing the RPV pressure because of the steam consumption by the HPCI turbine (seven times larger than that of the RCIC system).
After the HPCI system stopped, the RPV repressurized. Depressurization of the RPV to allow low-pressure pumps to add water was not started for 7 hours, and the RPV did not receive any water for that time. As with Unit 2, there were problems with power for the solenoid valves and the pressurized nitrogen needed for SRV operation. The water level decreased to below the fuel level, and significant core damage and hydrogen production occurred. Fire engines began alternative water injection (freshwater containing boron) into the reactor at ~9:25 a.m. on March 13. Later, the injection was changed to seawater; however, the water level in the RPV never recovered as expected, indicating a leak in the RPV or attached piping.
As with Unit 2, the containment pressure rise from decay heating was slower than expected, indicating the presence of a leak. In parallel with RPV depressurization, containment venting to decrease the PCV pressure was begun. Because of trouble with the solenoid valves and pressurized nitrogen supply, vent operations had to be done several times. Subsequently, at 11:01 a.m. on March 14, a hydrogen explosion5 occurred in the upper part of the reactor building. The source of the hydrogen is thought to be from leaks in the containment boundary. Longer term, the containment pressure has remained low.

There is enough there to damn the political, regulatory and corporate assurances from 1967 to the present time. All aspects of the feared events (first expressed in secret within the AEC) occurred. Loss of cooling, loss of coolant, inability to control emergency cooling, over heat, hydrogen, over pressure, unable to feed in water due to pressure, contain breach, meltdown.

All of this was argued at length and those with a view that the designs were insufficient were not listened to.

The ANS attitude regarding the DC power supply is insufficient. Perhaps in the US the facility to re connect to the grid would in every event take less than 8 hours. Patently that expectation is an American belief. And it let to a fundamentally flawed design being sold to Japan in the 1960s. And they have been time bombs waiting for a trigger ever since.

US reactors may or may not suffer the same triggers. Noone knows. Certainly not nuclear specialists who consider 8 hours battery life sufficient for components as critical as those which supply power to the ECCS and other soleniods so as to enable operation of the ECCS water pipes.

One hopes the USA does not suffer the same triggers as occurred in Japan. But if it does, it may have precious little time to consider the question: If the reactors power the grid, why is it that the reactor cannot power intrinsically and in an inviolate fashion, solenoid switches for the ECCS valves?

It is not hard. thermo couple, STB, steam turbine DC current.

In the meantime, the quick fix ordered by the NRC is the stationing of portable diesel powered electric generators at each site.

They have had since 1967 to comply with the relevant regulations regarding an integrated ECCS which must operate in an inviolate fashion for the period demanded by the nature of the decay heat generated by the longest live radio isotopes created in the core. Para 5 NRC acceptance criteria for Emergency Core Cooling Systems.

Whatever bentness and dishonesty the industry leaders in Japan came up with, it cannot in my view beat the design they were sold, lock and barrel. A design which gave a time limit, a count down to disaster.

The reality of the ECCS vulnerablity has been fudged from the start.

There will be plenty of people who won’t be that the ECCS in those reactors are NORMALLY
fitted with limited life battery power. When the batteries die, the ECCS dies. Yet the ECCS
and associated circuits are the last line of defense against containment breach and meltdown.
(Ergen, AEC, Task Force into Emergency Cooling Systems, 1967).

2 Responses to “Reactor 3 – essentially the same ECCS pipe valve failures as the rest.”

  1. CaptD Says:

    I think it is important to double check the “fault tree” in every reactor because it will not only tell us much about how they were affected by the earthquake but point out problems where the logs don’t match the data, something TEPCO is World Famous for doing.

  2. Plastic Valves Says:

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