This is the Archives and History of Changes, Etc. to Plant-related Parameters page.

Change history etc.

October 5, 2023
September 6, 2023
December 21, 2022
June 23, 2022
  • Maximum and minimum values of “Dust radiation monitor Channel A at the exhaust system for Unit 4 fuel removal cover” from June 1 to June 15 are as follows:Maximum value: 2.88E-07 (Bq/cm3) Minimum value: 5.80E-08 (Bq/cm3)
    Although there are slight fluctuation in the indicated values, we have confirmed that there is no abnormal increase in the indicated values compared to before and after said term and that there are no alarm for high radiation in concerned area.
    *Reference: Data from January 1, 2022 to May 31, 2022
    Maximum value: 5.11E-05 (Bq/cm3) Minimum value: 6.36E-08 (Bq/cm3)
June 1, 2022
  • Due to the review of the records of the operation diary of Units 1 to 4, "Data for every 1 hour / 6 hours (CSV)" (excluding Units 5 to 6) has been updated. (Change List (62.2KB) )
November 26, 2021
  • Due to changes in the implementation plan due to the completion of fuel removal from the Unit 3 spent fuel pool, the spent fuel pool water temperature column in the summary table and the Unit 3 6-hourly data (CSV) will be displayed as "-" from November 26.
November 18, 2021
  • From November 18, 2021 to AM 9:00 - PM 6:00 on November 19, 2021 (scheduled), some columns in Hourly/Six-hourly data (CSV) may be displayed as “-” due to equipment inspection for around 5 hours. (except for data of Units 5 and 6)
July 8, 2021
  • From AM 9:30 to 12:00 on July 9, 2021 (scheduled), some columns in Unit 6 Hourly data (CSV) may be missing due to equipment inspection.During the inspection, the data is measured by alternative meters.
June 17, 2021
  • From June 18 to 28, 2021 (scheduled), some columns in Summary Table and Unit 2 Hourly/Six-hourly data (CSV) will be displayed as “-“ due to equipment inspection.
May 28, 2021
  • From May 31 to June 4, 2021(scheduled), some columns in the Summary Table and the Hourly/Six-hourly data (CSV) of the Unit 3 will be displayed as “-“ due to equipment inspection.
March 26, 2021
  • Temperatures at 3 points (TE-2-3-69L1, TE-2-3-69L2 and TE-2-3-69L3) in the Bottom Head section of the Unit 3 Reactor Pressure Vessel (RPV) were excluded from planned data monitoring. Accordingly, “Temperature measurement points (Figure)” have been updated.
March 17,2021
  • From March 18 to 22, 2021 (scheduled), "Temperature in SFP" in Unit 5 hourly data will be displayed as "-" due to equipment inspection.
February 1,2021
  • Since data collection of equipment (monitors for reactor water level, pressure at reactor pressure vessel and PCV atmospheric radiation) confirmed to be unnecessary for monitoring based on the technical evaluation has been completed in line with the update work of the digital recorder of each unit, data display was changed to blank.
December 31, 2020
  • An error contained in Unit 3,4 six-hourly data (CSV) in the column of Unit 3"airborne radioactive concentrations (dust) at the nitrogen gas injection system to PCV" at 11:00 on December 30, 2020 was corrected on December 30, 2020 (original: 1.55E-06 → corrected: 1.55E-05).
December 7, 2020
  • Of the "Hourly/Six-hourly data (CSV)", value of "Primary Pressure of nitrogen gas injection to PCV" and the name of "Secondary Pressure of nitrogen gas injection to PCV" of the Unit 2 six-hourly data (CSV), were changed due to replacing of monitoring equipment.
    ・Value of "Primary Pressure of nitrogen gas injection to PCV" was changed from "-" to blank.
    ・Name of "Secondary Pressure of nitrogen gas injection to PCV" was changed to "Pressure of nitrogen gas injection to PCV".
November 10, 2020
  • Data for "PCV temperature (TE-16-007)", "PCV temperature (TE-16-008)" and "Water level inside PCV" of the Unit 2 six-hourly data (CSV), which is one of the "Hourly/Six-hourly data (CSV)", will be missing from November 10, 2020 in conjunction with PCV internal investigation and trial removal work.
October 19, 2020
  • Date of releasing one-hourly and six-hourly data (CSV) was changed to the latest measurement day due to a revision of operational procedure.
October 2, 2020
  • Date of releasing one-hourly and six-hourly data (CSV) was changed from the latest measurement day to the next day due to a revision of data disclosure procedure.
October 2, 2020
  • An error contained in Unit 1 six-hourly data (CSV) in the column of "airborne radioactive concentrations (long half-life noble gas) at the nitrogen gas injection system to PCV" at 11:00 on September 30, 2020 was corrected on October 1, 2020 (original: 8.66E-02 → corrected: 9.06E-02).
September 14, 2020
  • Errors contained in Unit 1 six-hourly data (CSV) in the column of “airborne radioactive concentrations (long half-life noble gas) at the nitrogen gas injection system to PCV” for 2017, 2018 and 2019 were corrected. (Change List(37.9KB))
September 8, 2020
  • Errors contained in Unit 1 six-hourly data (CSV) in the column of“airborne radioactive concentrations (long half-life noble gas) at the nitrogen gas injection system to PCV” for 2020 were corrected. (Change List(38.8KB))
April 16, 2020
  • Following changes were made to Every 6 hour Data (CSV) for Unit 1:
    - "Pressure of nitrogen gas injection to PCV" was changed to "Secondary Pressure of nitrogen gas injection to PCV".
    - Data monitoring for Shared pool FPC pump Inlet temperature (A), Shared pool FPC pump Inlet temperature (B) and Primary Pressure of nitrogen gas injection to PCV started.
February 27, 2020
  • Temp(1) (TE-2-3-69L1), Temp(2) (TE-2-3-69L2) and Temp(3) (TE-2-3-69L3) above are displayed as “-“ based on the announcement on November 30, 2017.
December 10, 2019
  • The following changes were made to Every 6 hour Data [CSV] for Unit 2:
    ・"The oxygen concentration of nitrogen gas separation apparatus (A)” was changed to "The nitrogen concentration of nitrogen gas separation apparatus (A)”.
    ・"The oxygen concentration of nitrogen gas separation apparatus (B)” was changed to "The nitrogen concentration of nitrogen gas separation apparatus (B)”.
    ・"The oxygen concentration of nitrogen gas separation apparatus (C)” was changed to "The nitrogen concentration of nitrogen gas separation apparatus (C)”.
November 13, 2019
  • Regarding the Every 6 hour Data [CSV] for Units 1 - 3, the number of decimal places for expressing the figures of the following items was changed to three.
    - Every 6 hour Data [CSV] for Unit 1
    ・Pressure of building inlet nitrogen gas injection
    ・Secondary Pressure of nitrogen gas injection to RPV(A)
    - Every 6 hour Data [CSV] for Unit 2
    ・Primary Pressure of nitrogen gas injection to RPV(A)
    - Every 6 hour Data [CSV] for Unit 3
    ・Pressure of building inlet nitrogen gas injection
    ・Secondary Pressure of nitrogen gas injection to RPV(A)
November 9, 2019
  • With the installation of an additional nitrogen injection line at Unit 3, the following changes were made;
    - Fukushima Daiichi Nuclear Power Station Plant Parameters (accessible by clicking "The newest data" below "Parameters related to the plants at Fukushima Daiichi Nuclear Power Station")
    ・Regarding the "Flow rate of nitrogen gas injection to Reactors" for Unit 3, "RPV" was changed to "RPV-A" and data monitoring for "RPV-B" started.
    - Every 6 hour Data [CSV] for Unit 3
    ・"Flow rate of nitrogen gas injection to RPV" was changed to "Flow rate of nitrogen gas injection to RPV(A)".
    ・"Pressure of nitrogen gas injection to RPV" was changed to "Primary Pressure of nitrogen gas injection to RPV(A)".
    ・"Pressure of nitrogen gas injection" was changed to "Pressure of building inlet nitrogen gas injection". Additionally the unit was changed from kPa to MPa.
    ・Data monitoring for Flow rate of nitrogen gas injection to RPV(B), Secondary Pressure of nitrogen gas injection to RPV(A), Primary Pressure of nitrogen gas injection to RPV(B) and Secondary Pressure of nitrogen gas injection to RPV(B) started.
October 5, 2019
  • With the installation of an additional nitrogen injection line at Unit 2, the following changes were made;
    - Fukushima Daiichi Nuclear Power Station Plant Parameters (accessible by clicking "Newest data" below "Parameters related to the plants at Fukushima Daiichi Nuclear Power Station")
    ・Regarding the "Flow rate of nitrogen gas injection to Reactors" for Unit 2, "RPV" was changed to "RPV-A" and data monitoring for "RPV-B" started.
    - Every 6 hour Data [CSV] for Unit 2
    ・"Flow rate of nitrogen gas injection to RPV" was changed to "Flow rate of nitrogen gas injection to RPV(A)".
    ・"Pressure of nitrogen gas injection to RPV" was changed to "Primary Pressure of nitrogen gas injection to RPV(A)".
    ・"Pressure of nitrogen gas injection" was changed to "Pressure of building inlet nitrogen gas injection". Additionally the unit was changed from kPa to MPa.
    ・Data monitoring for Flow rate of nitrogen gas injection to RPV(B), Secondary Pressure of nitrogen gas injection to RPV(A), Primary Pressure of nitrogen gas injection to RPV(B) and Secondary Pressure of nitrogen gas injection to RPV(B) started.
August 6, 2019
  • With the installation of an additional nitrogen injection line at Unit 1, the following changes were made;
    - Fukushima Daiichi Nuclear Power Station Plant Parameters (accessible by clicking "Newest data" below "Parameters related to the plants at Fukushima Daiichi Nuclear Power Station")
    ・Regarding the "Flow rate of nitrogen gas injection to Reactors" for Unit 1, "RVH" was changed to "RVH-A" and data monitoring for "RVH-B" started.
    - Every 6 hour Data {CSV} for Unit 1
    ・"Flow rate of nitrogen gas injection to RPV" was changed to "Flow rate of nitrogen gas injection to RPV(A)".
    ・"Pressure of nitrogen gas injection to RPV" was changed to "Primary Pressure of nitrogen gas injection to RPV(A)"
    ・Data monitoring for Flow rate of nitrogen gas injection to RPV(B), Secondary Pressure of nitrogen gas injection to RPV(A), Primary Pressure of nitrogen gas injection to RPV(B) and Secondary Pressure of nitrogen gas injection to RPV(B) started.
December 25, 2018
  • "Location of water gauges installed in the Primary Containment Vessels" were updated.
May 14, 2018
  • Following items ended their listing:
    - summary table for parameters related to the plants as of 5:00am - charts for parameters related to the temparature
March 26, 2018
  • Following data were added to the Unit 2 data set obtained every 6 hours (csv): The oxygen concentration of nitrogen gas separation apparatus (A) and The oxygen concentration of nitrogen gas separation apparatus (B) and The oxygen concentration of nitrogen gas separation apparatus (C).
December 1, 2017
  • Temperatures at 3 points (TE-2-3-69L1, TE-2-3-69L2 and TE-2-3-69L3) in the Bottom Head section of the Unit 3 Reactor Pressure Vessel (RPV)were excluded from planned data monitoring.
    Accordingly, "The most recent measuring instrument status based on data obtained every hour and every 6 hours (CSV)" and the "Temperature measurement points (Figure)" have been updated.
November 30, 2017
  • deficiencies were found in parts of the cables leading inside the pedestal below the Unit 3 Reactor Pressure Vessel (RPV), for three of the nine thermometers installed at the bottom section. Those three thermometers are considered to be broken because they were unable to measure the temperature there. Therefore, thermometers (temperature (1), temperature (2) and temperature (3) as above) have been excluded for monitoring the operational limit of being within 80 degrees at the RPV bottom section, as defined by Article 18 (Reactor water injection system) of the Specifications for Specified Nuclear Facility in Implementation Plan III. Monitoring is being carried out by the remaining six thermometers.
October 23, 2017
  • "The latest statuses of measurement instruments according to the data obtained every hour and every 6 hours (CSV)"was updated.
August 30, 2017
  • Unit 3 PCV temperature gauges (TE-16-002,TE-16-004) were selected as monitoring equipment.
    Data sampling started on August 30, 2017.
    Accordingly, "Temperature measurement point maps" have been updated.
July 19, 2017
  • Nitrogen gas injection into Unit 1 RPV started using the jet pump instrumentation rack line.
    Accordingly, data recording of the flow rate and the pressure on this line has been started in addition to the existing line.
July 10, 2017
  • Data recording of Unit3 PCV temperatures (TE-16-002,TE-16-004) were excluded as the monitoring objects.
    Accordingly, "Temperature measurement points map" has been updated.
May 12, 2017
  • Data recording of PCV temperatures (TE-1625T5, TE-1625T7) started on May 12 because they were selected as the monitoring objects.
    Accordingly, "Temperature measurement point maps" have been updated.
  • "Location of water gauges installed in the Primary Containment Vessels"has been updated due to the reinstallation of water gauges.
March 30, 2017
  • Real- time data of "Temperature at the RPV lowest point","Temperature in the PCV", "Amounts of water injection into the reactor", "Radioactive material concentration in the PCV" and "Hydrogen concentration in the PCV" were newly released.
March 2, 2017
  • Unit 1 PCV temperature gauges (TE-1625T3, TE-1625T6) have been missing since March 2, 2017 because they were excluded from the monitoring thermometer under the implementation plan.
January 25, 2017
  • As operations to reduce core injection water into Unit 1 (Step 3) began, new data were added to "Temperatures in the Primary Containment Vessels when the amounts of core injection water are reduced (data obtained for 24 hours after the operation)."
January 5, 2017
  • As operations to reduce core injection water into Unit 1 (Step 2) began, new data were added to "Temperatures in the Primary Containment Vessels when the amounts of core injection water are reduced (data obtained for 24 hours after the operation)."
December 15, 2016
  • As operations to reduce core injection water into Unit 1 began, information about the “Temperatures in the Primary Containment Vessels when the amounts of core injection water are reduced (data obtained for 24 hours after the operation)” was also added to the page.
December 14, 2016
  • Data of water levels inside Unit 1 PCV were newly added to the data set obtained every 6 hours (CSV).
  • Data of water levels inside Unit 2 PCV were newly added to the data set obtained every 6 hours (CSV).
  • Data of water levels inside Unit 3 PCV were newly added to the data set obtained every 6 hours (CSV).
  • Along with the additional data, information about the “Location of water gauges installed in the Primary Containment Vessels” was posted on the page.
December 1, 2016
  • Following data were added to the Unit 1 data set obtained every 6 hours (csv): airborne radioactive concentrations (dust and long half-life noble gas) and surface radiation of filter units at the nitrogen gas injection system to Unit 1 PCV and an area monitor of the Units 1-2 central control room.
  • Following data were added to the Unit 2 data set obtained every 6 hours (csv): airborne radioactive concentrations (dust and long half-life noble gas) and surface radiation of filter units at the nitrogen gas injection system to Unit 2 PCV and dust concentrations in the exhaust gas from the Unit 2 reactor building.
  • Following data were added to the Units 3-4 data set obtained every 6 hours (csv): airborne radioactive concentrations (dust and long half-life noble gas) and surface radiation of filter units at the nitrogen gas injection system to Unit 3 PCV, No. 31 area monitor of the Units 3-4 central control room, and dust radiation monitor Channel A at the exhaust system for Unit 4 fuel removal cover.
  • "The latest statuses of measurement instruments according to the data obtained every hour and every 6 hours (CSV)" were updated.
January 27, 2016
  • Data sampling at Unit 2 SUPPLY AIR D/W COOLER HVH2-16C (TE-16-114H#1) and SUPPLY AIR D/W COOLER HVH2-16E (TE-16-114K#1) stopped because they were excluded from the reference thermometers.
  • Data sampling at Unit 2 SUPPLY AIR D/W COOLER HVH2-16C (TE-16-114H#2) and SUPPLY AIR D/W COOLER HVH2-16E (TE-16-114K#2) started because they were selected as the monitored thermometers.
  • Data sampling at Unit 3 PCV thermometer (TE-16-002) and PCV thermometer (TE-16-004) started because they were selected as the monitored thermometers. For the above reasons, “The latest statuses of measurement instruments according to the data obtained every hour and every 6 hours (CSV)” and the “Measuring points of temperature (Figure)” were updated.
June 4, 2015
  • Unit 1 PCV temperature gauges (TE-1625T3,T1625T6) were selected as monitoring equipment.
    Data sampling started on June 4, 2015.
April 23, 2015
  • Unit 2 RPV temperature (TE-2-3-69R) was selected as monitoring temperature.
    Data sampling started on April 23, 2015.
    Accordingly, "temperature measurement point (figures)" and "latest status of the indicators in hourly/every six hours data (CSV)" have been updated.
April 23, 2015
  • Unit 2 RPV temperature (TE-2-3-69R) was selected as monitoring temperature.
    Data sampling started on April 23, 2015.
    Accordingly, "temperature measurement point (figures)" and "latest status of the indicators in hourly/every six hours data (CSV)" have been updated.
April 23, 2015
  • Unit 2 RPV temperature (TE-2-3-69R) was selected as monitoring temperature.
    Data sampling started on April 23, 2015.
    Accordingly, "temperature measurement point (figures)" and "latest status of the indicators in hourly/every six hours data (CSV)" have been updated.
April 7, 2015
  • The measurement values of Unit 1 PCV temperature (TE-1625T3,TE-1625T6) were excluded from the monitoring thermometer; therefore, we have updated "temperature measurement points (figures).
  • "Unit 1 Primary containment vessel's pressure indicator PT-1601-69 has been replaced to monitoring subsidiary indicator. From April 7th, 2015, midnight, on a 6 hourly data (CSV) primary containment vessel's pressure indicator PT-1632C was changed to PT-1601-69 and has been started the data samplings. Therefore, we have been updated the "latest status of indicators."
March 4, 2015
  • Unit has been changed from MPa to kPa due to the change in pressure gauge at Unit 2 Reactor Pressure Vessel, after the trend of reading was evaluated to be inappropriate for monitoring.
July 17, 2014
  • The "Measuring points of temperature (Figure)" has been updated due to the restoration of the monitoring thermometer at the points inside Unit 2 PCV (TE-16-007,TE-16-008).
May 17, 2014
  • From 23:00 on May 16, 2014, obtaining data from the reactor pressure vessel pressure gauge (PT-1632C) has been started, instead of primary containment vessel pressure gauge (PT-1601-69) at Unit 1 for the every 6 hour data (CSV). The primary containment vessel pressure gauge (PT-1601-69) has been excluded from the monitoring backup equipment.
    "The latest statuses of measurement instruments according to the data obtained every hour and every 6 hours" has been updated due to this change.
May 15, 2014
  • "Measuring points of temperature (Figure)" has been updated, since Unit 2 PCV temperature (TE-16-007,TE-16-008) is no longer a monitoring object specified by the Implementation Plan.
Apr 9, 2014
  • April 9.2014 "Measuring points of temperature (Figure)" and "the latest statuses of measurement instruments according to the data obtained every 6 hours (CSV)" were updated, since Unit 1 PCV temperature (TE-1625T3) has become a monitoring object specified by the Implementation Plan.
Apr 4, 2014
  • "Measuring points of temperature (Figure)" and "the latest statuses of measurement instruments according to the data obtained every 6 hours (CSV)" has updated, since Unit 1 PCV temperature (TE-1625T3) is no longer a monitoring object specified by the Implementation Plan.
Feb 20, 2014
  • The temperature of RPV of Unit 2 (TE-2-3-69R) excluded from instruments to be monitored under the operational safety regulation. 'The temperature measurement points (figure)' and 'the latest situation of the gauge in the data obtained every hour/six hours (CSV)' was updated accordingly.
Oct 2, 2013
  • Since a thermormeter was additionally installed inside the Unit 2 PCV, data recording of Unit 2 PCV temperature (TE-16-007 and TE-16-008) provided in "Data (Every 6 hour) CSV" was started at 5:00 AM on October 2, 2013. In addition, "Parameters related to temperature (Graph)" and "Measuring points of temperature (Figure)" was renewed.
  • We have corrected the name of the instrument (TE-2-3-69F1, TE-2-3-69F2 and TE-2-3-69F3) provided in "Data (Every 6 hour) CSV" and "Measuring points of temperature (Figure)" at Unit 2.
  • Since Unit 6 reactor was opened, data recording of Unit 6 reactor water level provided in "Data (Every hour) CSV" was started by using the "reactor water level open vessel" at 4:00 PM on September 20, 2013. In addition, "Stoppage range of reactor water level" has no longer been displayed (left as blank) since 4:00 PM on September 20, 2013.
Apr 9, 2013
  • After 5:00 AM on April 9, 2013, the data obtained by an alternative instrument RPV BELLOWS SEAL AREA(TE-16-114N#1) replacing Unit 2 RPV BELLOWS SEAL AREA (TE-16-114R#2) has been provided in the data obtained every 6 hours (CSV).
Mar 4, 2013
  • After 0:00 AM on March 4, 2013, the data of instruments judged to be "failed" included in the data obtained every hour/six hours (CSV) is no longer displayed (left as blank) as they are no longer used for evaluation and their reliability is low.
  • As for the data of Unit 2 SUPPORT SKIRT TOP (TE-2-3-69K1) included in the data obtained every six hours (CSV), the data of the alternative Unit 2 SUPPORT SKIRT TOP (TE-2-3-69K2) is provided instead after 5:00 AM on March 4, 2013.
  • The data of the PCV temperatures (TE-16-114W#1), (TE-16-114W#2)on March 4, 2013 are not displayed (left as blanks) in the data obtained every 6 hours (CSV) acquired at 11:00 AM on March 4 and later since the instruments were removed for the investigation of the inside of the PCV and permanent thermometer installation. The temperature measurement points (figure) have been updated accordingly.
Feb 18, 2013
  • As for the parameters related to Unit 1 water level, pressure and temperature obtained every hour (CSV), the data on reactor injection water flow rate (CS) as of 12:00 AM(Midnight) on January 23, 2012 has been corrected.
Jan 17, 2013
  • A document on the latest statuses of measurement instruments has been added (with the format of data obtained every hour and every 6 hours (CSV) changed).
Dec 4, 2012
  • The format of Unit 1 data obtained every 6 hours (csv) has been changed (click here for examples) and the temperature measurement points (figure) have been updated.
Nov 20, 2012
  • The data acquired at 1:35 and 12:25 on March 16, 2011 has been added to Unit 2 Parameters Related to Water Level and Pressure (CSV, graph)
Nov 14, 2012
  • The year in the "Parameters related to temperature" (CSV) for Units 1-3 in the 2011, 2012 archive has been corrected from 2012 to 2011.
DecNov 8, 2012ember
  • Unit 3 spent fuel pool water temperature and FPC skimmer surge tank water level as of 11:00 on November 7 on the Parameters Related to Plants (overview chart) have been corrected to match the note.
Nov 6, 2012
  • Format being changed and measuring points of temperature (Figure)
Nov 5, 2012
  • According to the data additions and corrections made to the past parameters related to the plants, the water level, pressure, temperature data of March 2011 was updated and the amounts of water injection into Units 1-3 reactors and the complementary document on the fire fighting pump flowmeter reading data (posted on June 13, 2011) have been replaced.(Go here for details on the changes made)
Sep 8, 2012
  • Thermometers of safety regulations of Unit2 has been deleted since it was excluded from instruments to be monitored under the Safety Regulation.
Aug 14, 2012
  • Format being changed since the data of 11:00 am, August 14, 2012.
Jul 12, 2012
  • Format being changed since the data of 5:00 am, July 12, 2012.
May 28, 2012
  • Data was corrected as we found that the wiring for the digital recorder of Unit 1 safety valve thermometer was done incorrectly.
Jan 19, 2012
  • Regarding the temperature data of Unit 1 as of 12:00 PM, January 18, the data table value on PDF page 3 was incorrect (we had uploaded the temperature data of Unit 2) from 3:00 PM, January 18 to 9:40 AM, January 19.
Nov 29, 2011
  • Incorrect data for pressure at Primary Containment Vessel of Unit 1 at Fukushima Daiichi Nuclear Power Station (Brief Overview)
Nov 11, 2011
  • Correction of pressure data of plant parameters in primary containment vessel D/W of Unit 2 in Fukushima Daiichi Nuclear Power Station
Jun 13, 2011
  • Correction of parameters related to the plants in Fukushima Daiichi Nuclear Power Station

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