Based on the Recovery Plan (submitted and published on January 31, 2012) prepared in accordance with the Nuclear Operator Emergency Action Plan, Fukushima Daini Nuclear Power Station is now proceeding with recovery of facilities for maintaining cold shutdown of the station.
We report the recovery progress status at the end of April 2012 as shown below:
1. Progress Status of the Recovery Plan
The recovery work of each unit is proceeding steadily.
- % in the chart shows the progress rate of recovery work as per the Recovery Plan (Up to the permanent installation) as of the end of April, 2012. % in ( ) shows the progress rate of the previous monthly report. See Appendix 1 for details.
- At the internal inspection after the permanent installation, the equipments subject to the Recovery Plan will be tested (for each unit).
Note: For Units 2 and 3, the rate is the same as the previous month because there was no change in each step. However, the recovery tasks are proceeding steadily.
2. Major Progresses Based on the Recovery Plan (April)
Unit 1 power panel (P/C 1C-1) installation
As a substitute for Unit 1 power panel (P/C 1C-1) damaged by the tsunami of Tohoku-Chihou-Taiheiyo-Oki Earthquake, a new power panel was manufactured and installed at the site (the annex of the Reactor Building) on April 19, 2012 [See Appendix 1 & 2]. Function check including withstand voltage test will be conducted on the power panel (P/C 1C-1) and permanent cable installation will be done to provide power supply to the related systems.
Function check of the residual heat removal cooling sea water system (B system)
The electric motor of Unit 1 residual heat removal cooling sea water system (B system) was fixed and the system was temporarily placed on the second floor of the Sea Water Heat Exchanger Building to reduce the impact of recurrent Tsunami. After water-tight work was completed for the building (March 31, 2012), the system was moved back down on the first floor on April 5, 2012. Then on April 12, 2012, the system was tested utilizing temporary power supply and cable, and no problems were found [See Appendix 1 &2]. Permanent cable installation will be done to proceed toward the permanent installation of power supply.
Permanent installation of Unit 4 residual heat removal cooling system, residual heat removal cooling sea water system and emergency diesel generator cooling system
As Unit 4 power panels have been permanently installed (P/C 4C-2 on January 30, 2012, P/C 4D-2 on March 23), these power panels are used as the power supply for Unit 4 residual heat removal cooling system (B system, C system and D system), residual heat removal cooling sea water system (B system, C system and D system) and emergency diesel generator cooling system (B system) from April 26, 2012 onward. Accordingly, the permanent installation of these systems has been completed [See Appendix 1 & 2].
3. Other Major Progresses (April)
Visual inspection of the inside of Unit 3 PCV
Visual inspection of the inside of Unit 3 PCV was completed on April 5, 2012. As we found no leakage of reactor coolant or deformation/damage of equipments and piping inside PCV, it has been concluded that there are no factors hindering the cold shutdown function. Though minor issues were found such as the paint inside PCV partially coming off (due to the temporary temperature rise after the plant shutdown) and rust on the surface of some equipments (due to humidity change), these do not have impact on the cold shutdown function (as informed on April 6, 2012). [See Appendix 3-1]
Inspection of the inside of Unit 4 main exhaust duct
From April 2 to 13, 2012, inspection of the inside of Unit 4 main exhaust duct was done in order to investigate the air leak from the duct occurred on June 8 and July 31, 2011 (Press releases issued on these dates). As a result, no issue was found. In addition, a displacement measurement (to measure the amount of duct deformation) was done on the duct from April 19 to 26, 2012. The measurement result will be evaluated and analyzed. [See Appendix 3]
In accordance with the four points to consider*
specified by the Nuclear Safety Commission when the cancellation of a nuclear emergency situation was declared, TEPCO is committed to continuously pursuing the measures for restoration from nuclear emergency and further reliability improvement.
As for the consideration point 4, the systems subject to the measures were selected at the end of March 2012. We are currently in the process of assessing impact on the selected systems.
1: Fukushima Daini Nuclear Power Station: Progress Status Based on the Recovery Plan (As of the End of April 2012) (PDF 67.4KB)
2: < Photos > Major Progress Statuses Based on the Recovery Plan (April) (PDF 172KB)
3-1: < Photos > Other Major Progresses (April) (PDF 117KB)
3-2: < Photos > Other Major Progresses (April) (PDF 54.5KB)
4: < Photos > Other Topics (PDF 123KB)
* Four points to consider specified by Nuclear Safety Commission
On December 26, 2011, the Nuclear Safety Commission submitted a proposal to the Prime Minster that the cancellation of a nuclear emergency situation of the TEPCO Fukushima Daini Nuclear Power Station is allowed to be declared, along with four points to consider for the issuance of the declaration. On January 11, 2012, the Nuclear and Industrial Safety Agency at the Ministry of Economy, Trade and Industry issued instructions to observe the consideration points when preparing and implementing the Recovery Plan for Fukushima Daini Nuclear Power Station.
1. Part of the facilities at the Fukushima Daini Nuclear Power Station is temporary installation, to which appropriate maintenance should be provided. The dependence rate of the temporary installation should be reduced according to a plan.
2. The safety facilities for part of the residual heat removal systems have not yet been recovered, to which appropriate management should be provided according to the situation until the recovery of these facilities. In preparing for natural disasters and other incidents, all possible measures should be taken to ensure safety.
3. Thorough safety management including the safety of workers should be implemented.
4. Based on the past pressure and temperature records before cold shutdown that showed abnormal values different from those during a regular period, impacts of these elements on the facilities should be considered.