sick puppies…

This is a band.  http://en.wikipedia.org/wiki/Sick_Puppies  I’ve heard it on the radio a few times.  They actually sound very good….

But we’ve also got one of these in the house at the moment.  Little Stella it seems is susceptible to getting bladder infections.  We are on round 3 of antibiotics after another visit to the vets on Saturday morning and we’re trying to encourage lots of water drinking to flush everything out.  This involves – among other things – drinking Bovril and eating ice cubes.  Fortunately (?), It doesn’t seem to have affected her energy levels though…. 😉

We have had some lovely spring weather here but apparently rain is on the way. 

Work has still been very slow for me so I’m having to have a serious think about what to do about that…. It’s been quiet since I started but I managed to keep occupied up until Christmas.  I can’t really say the same for this year.  If it stays this way for much longer, I’ll have forgotten what radiation is…..

On that note, I was getting asked quite a lot of questions at work about what has happened at the reactor in Japan and was asked to put into context the radiation levels that are being banded around in the media.  Here is the information I pulled together which a few people have been interested in. There is lots more stuff available on the internet.  A couple of the more “reliable” sites I’ve found are:

http://www.ionactive.co.uk/blog.html
http://www.world-nuclear-news.org/

All –  
I have been asked a few questions the past couple of days from people trying to put into perspective what is happening at the reactors at Fukushima.  It might be worth giving a bit of context – from my perspective – to what’s happening.  I have to admit, I have found it very difficult from the news to get a really good feel for what’s really going on…  The information generally leaves us radiation “geeks” with lots of unanswered questions.  

One of the key things I’ve noticed is that there often isn’t a distinction made between internal radiation (airborne activity/contamination) and external radiation in the reports that are coming out. 

  • External radiation is a hazard to the workers on the plant and will have little effect on the people outside the site fence. 
  • Internal radiation could become a hazard when airborne activity from the release from the plant is breathed in.  Eating or drinking contaminated foodstuffs or contamination getting deposited on surfaces (including clothing) and then later getting disturbed and inhaled or ingested also could result in intake into the body. 

In an emergency situation, the public is given advice on sheltering and evacuation which at Fukushima has affected ~200,000 people.  This advice will be given based on current and predicted wind direction, weather conditions and the calculated radioactive source term of the release.  These measures are in place to protect against the potential for internal dose.  Later on further countermeasures such as restrictions on eating locally produced foods and drinking the milk, decontamination of roads and houses or complete relocation of people may need to be applied.  I couldn’t begin to speculate on the extent of the long term countermeasures that may be required here.

Here are some of the specific things that I have read on the World Nuclear News’ reports of the event:

External radiation 

  • “One worker received a radiation dose of 106 mSv.” This dose is too low to cause immediate, deterministic effects but is 5 times greater than the UK’s legal dose limit.  As a result of this dose, this worker will have a less than 1% increased risk of getting a fatal cancer. 
  • “Radiation levels on the edge of the plant compound briefly spiked at 8.217 mSv/hr but later fell to about a third that.” The dose received after one hour at the maximum level would be equivalent to about a year’s dose received living in Cornwall. 
  • “Radiation levels at the plant site between units 3 and 4 reached a peak of some 400 mSv/hr.” – Within a couple of hours exposure at these levels, operators would begin to experience  the deterministic effects of radiation.  This might include feelings of nausea. 

Internal radiation
It is a bit harder to figure out what’s going on here.  The prevailing wind direction appears to be out to sea but there are also reports that “radiation in Tokyo is 10 times normal”.  This is still very low levels and would have no detrimental health effects to people living there.  Instruments that measure radiation are very sensitive and can detect radiation at levels much, much lower than could cause any effect on health. 

  • “Out of about 100 residents evacuated from Futaba by buses, nine people were found to have been exposed.”  This will be due to airborne activity from the releases from the plant and the resulting contamination.  They may have had to remove items of clothing or cleaned themselves to remove contamination from their skin.  Urine sampling may also be undertaken to determine if any significant internal dose has been received by these people.  It is worth emphasising that modern radiation instruments are very sensitive and can detect radiation at levels well below those that would cause health effects.  

There has also been reporting of radiation levels reducing dramatically following maximum “peaks”.  Some of the isotopes that will have been released from Fukushima have very short half lives and decay away very quickly (i.e. seconds).  By the time the plume blows cross the site boundary, the activity from these will have reduced significantly. 

In the UK, the legal annual whole body dose limit is 20 mSv.  Our lifetime risk of getting a fatal cancer is between 25030%.  Exposure to 1000 mSv of radiation is estimated to increase that risk by around 5%.

This graphic might help to put things in perspective….