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

1. 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
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2. 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 63
Limiting 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

5. [Type text]