Last edited on 2011-04-04 05:43:12 by stolfi

Plots of reactor data - Fukushima Daiichi - Units #1--#3

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, after the march/2011 earthquake and tsunami. Note that the incident started on 2011-03-11 (friday).

Plots

Reactor 1 Reactor 2 Reactor 3
plot: reactor 1 plot: reactor 2 plot: reactor 3

Quantities

Core pressure

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. Note also that the tic spacing in the top half of the plot is 10 times that of the bottom half.

Drywell pressure

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.

Torus pressure

This quantity is the absolute pressure (kPa) in the surge suppression chamber, the torus (donut) shaped chamber below the drywell container. A value of 101 kPa means the same as outside air pressure.

Core noz. temperature

This quantity is the temperature (Celsius) of the reactor's (inner) pressure vessel, taken at the injection nozzles. The upper limit of the sensor's range (400 C) was exceeded on some occasions.

Core bot. temperature

This quantity is the temperature (Celsius) at the bottom of the reactor's (inner) pressure vessel. The upper limit of the sensor's range (400 C) was exceeded on some occasions.

Drywell radiation

This quantity is the radiation level (Sievert per hour) in the drywell, as measured by the CAMS instrument. Note:The scale is logarithmic.

Water level

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".

Water injection rate

This quantity is the rate at which water was pumped into the (inner) reactor pressure vessel, in liters per minute. Some of it was saltwater, some freshwater; some was injected through the fire extinguisher lines, some through the water feed line.

Data sources

Some values of core pressure, drywell pressure, and water level of reactor #1 (only) between 2011-03-11 22:00 and 2011-03-12 15:28 were eyeballed from a graph found on a Physics Forum post by user "Fred".

The water level and pressure data from 2011-03-12 15:30 through 2011-03-17 were taken from a PDF document titled 'Condition of the plants of the unit 1-3 at FI site', fetched from the Nuclear Information and Resource Service (NIRS) site on 2011-03-22. That site attributes the data to the Citizens' Nuclear Information Center in Tokyo. Core pressures in that document were gauge readings relative to atmospheric pressure ("MPa g"), 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.

Data from 2011-03-22 onwards (water level, injection rate, pressure, and temperature) come from the Nuclear and Industrial Safety Agency (NISA) News Releases, either the English version or the Japanese version.

For further information please contact the document authors.

Data files

The data was copied by hand from the source documents into a separate text file fo each reactor, namely:

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.

Corrections

Some data were almost certainly typos and were corrected (hopefully) as follows:

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 what are the correct values:

Plotting

The plots were created by a gnuplot-based Linux shell script.

Disclaimer

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 its author (me) nor UNICAMP should be held responsible for any damages that may result from the use of this information. Corrections and suggestions are welcome.