see http://www.simplyinfo.org/?p=5855 for complete article
Simplyinfo crowd-sourced analysis is that earthquakes caused Unit 1 to leak even more radiation in spikes, and that Unit 1 had problems requiring shutting of Isolation Condensor within minutes of automatic activation, radiation was released and detected almost immediately when tsunami waves struck, showing major leakage of radiation BEFORE losing diesel geneators, and complete loss of wather within hour of power loss.
Conclusion:
** These are estimates based on known conditions and observed data **
Simplyinfo crowd-sourced analysis is that earthquakes caused Unit 1 to leak even more radiation in spikes, and that Unit 1 had problems requiring shutting of Isolation Condensor within minutes of automatic activation, radiation was released and detected almost immediately when tsunami waves struck, showing major leakage of radiation BEFORE losing diesel geneators, and complete loss of wather within hour of power loss.
Fukushima Unit1 Group Findings
Unit 1 Group Findings
Earthquake And Corium Issues:
We found an ongoing trend where significant earthquakes of 6.0 or higher that occurred near Fukushima Daiichi caused significant changes in unit 1. On July 31, 2011 there was a 6.4 earthquake. The radiation readings at Drywell B in unit 1 had been below 300 sV/h until the earthquake. After the earthquake radiation readings jumped to 356 sV/h. A 56 sV/h or greater jump.
Other changes were noted along with the radiation increases including temperature and pressure changes at various reactors. These did not have the clear constant pattern that the unit 1 drywell radiation did. The conclusion on the radiation Drywell B spikes at unit 1 are that corium forms a crust as it cools. Our conclusion is something that has not been covered by any known analysis for post core meltdown accidents. Significant earthquakes or major after shocks cause the crust formed over the corium to break open and release radiation which were then sensed by the radiation monitors.
UNIT 1 Started Melting in Only 17 Minutes
Unit 1 Rapid Meltdown Issues:We have looked into the issue surrounding unit 1′s rapid meltdown at length. Unit 1′s core became uncovered (without water) after only 17 minutes where units 2 and 3 took 337 minutes and 315 minutes respectively. What issues went into unit 1′s rapid and unique demise may go back to it’s older design and human intervention that inadvertently made things worse.
- The quake hit at 14:46 on March 11, 2011. Unit 1 successfully went into a seismic SCRAM to put the reactor into emergency shut down.
- NHK reports that at 14:56 the IC (isolation condenser) was manually shut down by workers at unit 1. (10 minutes after scram)
- At 15:27 the tsunami hits.
- At 15:29 the radiation monitor 1 mile from unit 1 detects high levels of radiation. (only 2 minutes after tsunami hits)
- 15:41 the second diesel generator fails causing complete loss of A/C power.(from flooding)
- 16:36 the IC at unit 1 had boiled dry. (less than one hour after power loss)
** These are estimates based on known conditions and observed data **
Note: Initial Condition Assumed at Reactor SCRAM + 10 minutes to Station Blackout
All times are in minutes.
SCRAM = Emergency shut down of a nuclear reactor.
HPCI = High Pressure Coolant Injection
RCIC = Reactor Core Isolation Cooling
SORV = Safety Operated Relief Valve
All times are in minutes.
SCRAM = Emergency shut down of a nuclear reactor.
HPCI = High Pressure Coolant Injection
RCIC = Reactor Core Isolation Cooling
SORV = Safety Operated Relief Valve
| 5/17/2011 ACCIDENT PROGRESSION IN MINUTES | |||
| Event | Case 1 | Case2 | Case3 |
| Station Blackout | Station Blackout | Station Blackout | |
| No HPCI/RCIC | Manual HPCI/RCIC | Normal HPCI/RCIC | |
| NO SORV | Manual SORV | Normal SORV | |
| Core uncovered | 17 | 337 | 315 |
| Start core melt | 57 | 396 | 388 |
| Corium slumps to bottom head | 78 | 453 | 419 |
| RPV bottom head fails | 142 | 543 | 515 |
| Corium starts boil off of water @ concrete containment floor | 142.5 | 543.5 | 515.5 |
| Corium starts melting containment floor | 162 | 544 | 580 |
| Containment failure and leakage starts | 185 | 596 | 601 |
| Drywell and Wetwell electric penetrations start to leak at T=204C – 400F | |||
| Drywell and Wetwell electric penetrations decompose and blow out of containment at T=260C – 500 | |||
Table 1 Accident Progression Timeline
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