Table 2: Unit 2 Reactor: Fukushima Daiichi Nuclear Power Plant - 11 May 2011

TABLE 2. UNIT 2 REACTOR: FUKUSHIMA DAIICHI NUCLEAR POWER PLANT: 11 MAY 2011 ASSESSMENT OF STATUS IN TERMS OF FUNDAMENTAL SAFETY FUNCTIONS FOR ACHIEVING A SAFE STATE Necessary safety function and TEPCO Roadmap Observation Evaluation of safe state conditions countermeasures Reactor is subcritical and sub-criticality - No power spike or power increase ACHIEVED No additional Control of Reactivity is demonstrated and maintained - No significant neutron flux measured and reported Caution: countermeasures reported - Short lived fission products are not reported at the - Continue detection of neutrons moment (e.g. La-140) and short-lived isotopes Stable cooling shall be assured - Reactor vessel temperature is: (115.1 °C at NOT ACHIEVED Nos 1, 3, 4, 7, 8, 9, 13, 14, - Keep the coolant temperature feedwater nozzle, reactor pressure vessel Establishment of a long term closed- 16 and 17 Residual heat removal sufficiently below the boiling point pressure ≤ 1.0 atm based on available loop heat removal circuit is advised at atmospheric pressure measurements) - Cover the damaged core adequately - Water level of reactor core is below about with water −1500 mm (A) and −2100 mm (B) from the top - Off-site and back-up power supply of active core shall be available - Off-site power supply and backup power from - Achievement of long term closed- portable diesel generators are available loop heat removal capability - Fresh water injection is provided; however, closed-loop heat removal is not yet established - Containment is leak-tight - Containment is believed to be damaged: latest NOT ACHIEVED Nos 2, 6, 11 and 15 - Containment pressure is maintained measurements show the containment pressure to - Measures to make the Containment below design limits be around atmospheric containment leak-tight should integrity - Hydrogen explosion to be - Containment probably damaged following be pursued prevented. hydrogen explosion at this unit at 21:14 UTC on - Pressure and H2 concentration of 14 March 2011 the containment to be further monitored - Reactor pressure vessel (including - Reactor pressure vessel is assumed to be NOT ACHIEVED Nos 5, 10, 29–46, 50, 54 radioactive material connected systems) should not leak; leaking, most probably through connected Construction of a cover above the and 55 or if so the leakage shall be recirculation system (pump seal loss of coolant reactor building has to be pursued Confining confined within allowable limits accident) - Leakages from the containment - Containment is believed to be damaged: latest should be prevented or controlled, measurements show the containment pressure or shall be confined and reactor pressure vessel pressure to be around atmospheric[Type text]

Necessary safety function and TEPCO Roadmap Observation Evaluation of safe state conditions countermeasures - No additional releases shall be - Intermittent releases have been observed NOT ACHIEVED Nos 12, 47–49, 51–53, 55– anticipated - Radiation monitors are available Measures to prevent radioactive 63Limiting effects of releases - Radiation monitoring measurements - White smoke is observed emanating releases and leaking of water with The transfer of stagnant shall be available continuously from the reactor building high level radioactivity to the water from the turbine - Samples of water in the turbine building floor environment should be further building to the radioactive area show high radioactivity releases from the pursued waste treatment facilities is reactor and the containment to the environment continuing Work to block the trench pit to prevent release of water with high level radioactivity to the environment is ongoing

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Table 2: Unit 2 Reactor: Fukushima Daiichi Nuclear Power Plant - 11 May 2011

by International Atomic Energy Agency on May 13, 2011

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Table 2: Unit 2 Reactor: Fukushima Daiichi Nuclear Power Plant - 11 May 2011 Presentation Transcript