ScribbleLive

@dean It might be worth exploring the idea of getting some of the various nuclear issue groups on board with this. It is a simple idea that could change lots of problems. There are lots of these localized groups trying to deal with issues at specific NPP's that the NRC is not properly addressing. I wonder if a petition would have any teeth to send to congress?

@ lilly we should study it and become familiar with current work first, my initial thoughts are,, higher power means higher flux levels and higher flux levels mean higher flux affects on the shroud which could result in premature cracking etc.. and the reactor vessel wall fluence values would increase which could accelerate potential issues.

The nuclear properties of fuel cladding material must also be satisfactory. For thermal reactors, it is important that the material have a reasonably small absorption cross section for neutrons. Only four elements and their alloys have low thermal-neutron absorption cross sections and reasonably high melting points: aluminum, beryllium, magnesium, and zirconium. Of these, aluminum, magnesium, and zirconium are or have been utilized in fuel-element cladding.

Aluminum, such as the 1100 type, which is relatively pure (greater than 99%), has been used in low power, water-cooled research, training, and materials testing reactors in which the operating temperatures are below 100°C. Magnesium, in the form of the alloy magnox, serves as cladding for the uranium metal fuel in carbon-dioxide cooled, graphite-moderated power reactors in the United Kingdom. The alloy zircaloy, whose major constituent is zirconium, is widely used as the fuel-rod cladding in water-cooled power reactors. The alloys in common use as cladding material are zircaloy-2 and zircaloy-4, both of which have mechanical properties and corrosion resistance superior to those of zirconium itself. Although beryllium is suitable for use as cladding, it is not used due to its high cost and poor mechanical properties.

The choice of cladding material for fast reactors is less dependent upon the neutron absorption cross section than for thermal reactors. The essential requirements for these materials are high melting point, retention of satisfactory physical and mechanical properties, a low swelling rate when irradiated by large fluences of fast neutrons, and good corrosion resistance, especially to molten sodium. At present, stainless steel is the preferred fuel cladding material for sodium-cooled fast breeder reactors (LMFBRs). For such reactors, the capture cross section is not as important as for thermal neutron reactors.

@dean It sounds like a bit of an experiment even if the aspects have been researched on paper, to try them in a commercial NPP without extensive actual testing first.

@ lilly.. they do test these in testing conditions first and that is another point, using a NPP for a test platform on new fuel design is WRONG in my view... they put an element in with the new mods and see how it performs, they calculate how it's supposed to behave but they never use a TEST REACTOR to proof test the system..STRIKE TWO..

one of the reports talked about a fuel pellet container and NRC intervention was needed to decide what to do with the pellets, how long to store them in the container before removing.. photo's indicated the over heating of the container bottom and sides when it was lifted out

@dean right. I think I read that GE fuels has a test reactor but that doesn't mean every fuel mfg does or uses them. JAEA might have info on fuel experimentation or maybe Japan fuels? If the LEU is made domestically in Japan and they were tinkering with different cladding that would be good to know.
There is a public meeting on Cooper about procedural and whatnot type changes there. I think there may also be a meeting about the longer fuel cycle. It would be useful to get technical details on how/why they are going to make the fuel cycle longer. It is a Mark 1 unit. Ooh I just thought of something. We were looking at fuel cycles in Japan at one point when we were documenting the mOX inventories. I wonder if Japan was on a 18 or 24 month fuel cycle. Smoss or Elaine might remember otherwise I could go diving into old notes.

I thought Japan had the shorter fuel cycles

Fuel Cladding Failure Experience
Numerous fuel cladding failures from various causes have been reported over the years. For example, the water flowing through the reactor core has caused fuel rods to sway back and forth. In this situation, the fuel rods vibrate against the grid (shown in Figure 2) and damage the cladding. At other plants, debris in the reactor water, such as metal flakes from rusted piping, has lodged against the grid. The friction from the vibration of this debris damaged the cladding. Another failure mode results when fuel pellets expand faster than the fuel rod cladding (see Figure 1) as their temperatures increase. The expanding pellets stretch the cladding, sometimes until it cracks or splits. Finally, the welds holding the upper and lower end plugs to the fuel rod cladding (see Figure 1) have sometimes been defective, causing pinhole leaks or even cracks to form. Other failure modes have been experienced too. Many, if not all, nuclear plants have experienced fuel cladding failures during their lifetimes. Few plants have shut down early to remove failed fuel rods. @ lilly.. I have been involved on some of the testing with this

Smoss established 18mo fuel cycle for MOX at Fuku houseoffoust.com

Not sure on the LEU reactors

older plants didn't have a 2:3 logic system which allows the maintenance on 1 channel while the logic then goes to 2:2... instrument upgrades were made to install these plant protective systems... thus.. if the older japan reactors didn't have the upgrades they would be forced to shutdown so that calibrations and maintenance could be done... now, one thing they could do is just change the periodicity on calibrations which is risky

IAEA released the report on decontamination remediation for Japan www.iaea.org

@dean Official comments on unit 3 claim the MOX had nothing to do with the epic explosion. Knowing the issues with the MOX fuel it has to have a role, degraded cladding when they started then a major accident

I say BOGUS on that official comment,, first thing bad about MOX is how it behaves in severe accident conditions

there is a radiation mapping release here for the 12th www.mofa.go.jp

@elainekirk If you find more from MEXT that has details of the survey in Akita prefecture let me know. They finished the survey there. Curious how it compares to local detecting

Out to go stimulate the economy - back in a few hours

@elainekirk it's strange indeed.

some dozen bottles of radium hidden there for decades sure would be more dangerous than some cesium since march, especially for the people living in the house. *shiver*

@elainekirk it was empty ?