Last edited on 2011-03-29 03:36:54 by stolfi
Jorge Stolfi
2011-03-23 02:40
The following plots show the partial evolution of physical quantities in the Fukushima Daiichi reactors #1, #2, and #3, during a the march/2011 incident. Note that the incident started on 2011-03-11 (friday), two days before the start of the plots.
This quantity is the water level inside the (inner) reactor pressure vessel, in millimeters, measured from the top of the fuel elements. Negative values mean that the fuel is partly out of the water. The "B" reading is used in preference to "A".
This quantity is the absolute pressure in the inner reactor pressure vessel, in kilopascals (kPa). The "B" reading is used in preference to "A" or "C". Note that 101 kPa is approximately 1 bar (one atmosphere) i.e. the pressure inside the core is the same as that of air outside the building.
This quantity is the absolute pressure (kPa) in the "drywell", the outer pear-shaped steel container that surrounds the reactor. A value of 101 kPa means the same as outside air pressure.
This quantity is the absolute pressure (kPa) in the suppression container, the torus (donut) shaped chamber below the drywell container. A value of 101 kPa means the same as outside air pressure.
This quantity is the temperature (Celsius) of the reactor's (inner) pressure vessel, taken at the injection nozzles. Note:The value is multiplied by 10 for clarity. The upper limit of the sensor's range (400 C) was exceeded on some occasions.
This quantity is the temperature (Celsius) at the bottom of the reactor's (inner) pressure vessel. Note:The value is multiplied by 10 for clarity. The upper limit of the sensor's range (400 C) was exceeded on some occasions.
The water level and pressure data through 2011-03-17 come from the NIRS PDF document titled 'Condition of the plants of the unit 1-3 at FI site', fetched from the Nuclear Information and Resource Service site on 2011-03-22. That site attributes the data to the Citizens' Nuclear Information Center in Tokyo.
Core pressures in that document were relative to atmospheric pressure, so they were incremented by 101 kPa to match the other pressures (all absolute).
The temperature readings from 2011-03-19 06:30 to 2011-03-22 15:30 were obtained from a scanned worksheet presumably prepared by TEPCO. After 2011-03-22 the data weer taken from the NISA bulletins (see above).
Data from 2011-03-22 onwards (water level, pressure, and temperature) come from theNuclear and Industrial Safety Agency (NISA) News Releases, either the English version or the Japanese version.
For further information please contact the document authors.
The water level and pressure data were entered by hand into a separate text file fo each reactor, namely data-un1.txt, data-un2.txt, and data-un3.txt. The emperature data was placed in separate text files heat-un1.txt, heat-un2.txt, and heat-un3.txt.
Values that were missing in the original documents are encoded as "99999" in these files. Entries that were marked "down scale" are encoded as "88888". (It seems that many of these may be "over scale" instead.) Missing and out-of-scale values appear as gaps in the plots.
The core pressure of reactor #1 on 2011-03-16 6:00 was given as "0.62 MPa" in the NIRS table. That must be a typo. I have corrected (hopefully) the value to "0.162 MPa".
A few other values in the original source documents are so different from their neighbors (both before and after them) that they must be errors too. However it is not clear which are the correct values:
The plots were created by a gnuplot-based Linux shell script.
IMORTANT: These plots, scripts, and data files are provided "as is", for the reader's convenience, with no guarantee whatsoever. There may be errors in the original document and/or in my processing of it.
This page is not an official document of the State University of Campinas (UNICAMP). Neither me nor UNICAMP should be held responsible for any damages that may result from the use of this information. Corrections and suggestions are welcome.
