Recent content by rmattila

  1. rmattila

    What would be the best way to divide a depot tablet?

    The situation is as follows: there is an off label use for quinidine that would require a 10 mg dose. However, the only format available is a 200 mg plastic depot tablet that is very difficult to crush homogeneously. I am not aware of the chemical form quinidine is in at these tablets, and...
  2. rmattila

    Bioinformatics project to help find cure for ALS

    Hello, we (*) are trying to set up a combined neuroscience/information technology project for the following purpose: ALS is a fatal neurological disease that has no known cause or cure and kills its victims within a few years. Our view is that one reason why all drugs have failed in clinical...
  3. rmattila

    Mechanical Nuclear coolant pumps built on turbine to generator shaft?

    Also, in Fukushima the main turbines tripped and the shaft stopped right at the earthquake because the acceleration exceeded the turbine trip level.
  4. rmattila

    Fukushima Japan Earthquake: nuclear plants Fukushima part 2

    As regards the operating license of the reactor pressure vessel, I suppose the practice is about the same in all countries. Pressure vessels in VVER-440 PWR reactors are especially challenging with respect to neutron fluence due to very small diameter of the RPV and a welding seam in the core...
  5. rmattila

    Fukushima Japan Earthquake: nuclear plants Fukushima part 2

    My primary concern at Western plants and Defence-in-depth thinking is that the plant's internal electricity grid appears to be recognized simply as provider of power to the equipment, not as a means for fault propagation. There are several possible failure modes in the plants' busbars, including...
  6. rmattila

    Fukushima Japan Earthquake: nuclear plants Fukushima part 2

    I suppose the criticality issue arises from someone trying to explain the concept of criticality to a listener who has watched too much Ghostbusters, and hence the "if two rods touch each other" meme was born.. Qualitatively, there are three issues that might reduce the margin to criticality...
  7. rmattila

    Fukushima Japan Earthquake: nuclear plants Fukushima part 2

    Just to keep some international perspective, here's my post from two years ago:
  8. rmattila

    Fukushima Japan Earthquake: nuclear plants Fukushima part 2

    In the Fukushima design, the rupture disk is in series with the two closed valves that must first be opened in order for the pressure to work on the disk. If the valves are not opened in time, the containment will develop a leak and the pressure might never reach the disk burst pressure again...
  9. rmattila

    Fukushima Japan Earthquake: nuclear plants Fukushima part 2

    This argument is very difficult for me to follow, as the very idea behind the design in the 80's was to eliminate the need for unreliable decision-making in the case of a severe accident by enabling a completely passive initiation of venting. If your vent lines don't have filters, you probably...
  10. rmattila

    Fukushima Japan Earthquake: nuclear plants Fukushima part 2

    The filtered venting system is designed to conduct the hydrogen from the containment to the stack in a controlled manner. At least in the Finnish and Swedish system this happens completely passively by means of a rupture disk, unlike the Japanese/American hardened vents, which require active...
  11. rmattila

    Fukushima Japan Earthquake: nuclear plants Fukushima part 2

    http://pbadupws.nrc.gov/docs/ML1214/ML12143A336.pdf Some specifics of the Swedish and Swiss filtered vents as seen by the NRC. http://pbadupws.nrc.gov/docs/ML1217/ML12178A670.pdf Report from the fact-finding trip.
  12. rmattila

    Fukushima Japan Earthquake: nuclear plants Fukushima part 2

    See http://tvo.fi/uploads/julkaisut/tiedostot/ydinvoimalayks_ol1_OL2_ENG.pdf page 12 for a picture of the setup. The line connecting the scrubbers to the containment drywell (one of the two) has two manual valves that are kept open, and a rupture disk that will break automatically at certain...
  13. rmattila

    Fukushima Japan Earthquake: nuclear plants Fukushima part 2

    The large gravel bed dry filter is only installed in the poorly situated and now shutdown Barsebäck NPP. Other Nordic BWRs use a compact wet scrubber filtered venting with jet nozzles injecting in NaOH water. The wet scrubber takes 99.9 % of Cs and around 99 % of elemental iodine, but unlike the...
  14. rmattila

    Cold shutdown that doesn't require coolant circulation?

    That design gets pretty close: http://www.rosatom.ru/wps/wcm/connect/spb_aep/site/resources/f3b59380478326aaa785ef9e1277e356/AES-2006_2011_EN_site.pdf [Broken]
  15. rmattila

    Japan Earthquake: nuclear plants

    The NRC voting record on the venting issues: http://www.nrc.gov/reading-rm/doc-collections/commission/cvr/2012/2012-0157vtr.pdf
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