Ionactive Consulting Blog

OK, so it has been a long time again since the last blog post. Been even busier than before - I will highlight some of the interesting radiation related topics in a later post.

Spent Saturday at the Woodcote Steam Rally near reading. What a fabulous event for all the family - whether you are into steam engines, classic cars, fairground rides, beer festivals or animals there is something for everyone.

I think the highlight for my sons Alex (6) and Ben (3) was a helicopter ride - I was amazed how calm but excited they were about it - handled the event really well with smiles all around. Not sure same could be said for mum watching the three of us take off into the sky - but her smiles returned as soon as we were safely back on the ground!


Here we have Alex and Ben undertaking a few last minute safety checks.




And we are off !




Alex takes the co-pilot position and attends to the navigation:




Ben takes the back seat with Dad - the headphones a tad too big I think!



Amazing trip indeed - all 6 minutes of it!

Oh, and not once did I consider the cosmic radiation dose rate at height - although at 1000-2000 feet I was not going to see much difference from ground level background anyway!

 

Work Rate

Not been keeping this blog up to date as much as I would like - it is not that it is a bind or pain, rather it is because I feel quite exhausted much of the time and simply do not have the energy to write. Part of this is to do with the rate of work - it is true that the last 6 months or so have been slower than I would have liked (despite the economy apparently being on the way up), but recently it has gone mad and work has arrived all in one go. Whilst this is welcome it does mean that the weeks / months are now a whirl of travel, assessments, critical examinations, training and similar. Training is really growing and this always takes a lot of preparation time.

I'm not sure if this sudden surge has been caused by clients all deciding they need advice / training at the same time, or if this is indicative of a release of resource after perhaps keeping the belts tightened for the last year or so. Compliance work (i.e statutory Radiation Protection Adviser related) has not relented, but I think discretionary spend (i.e certain training, radiation project related work and similar) has in part taken the back burner.

Indeed, we have slowed the pace of our site radiation protection resource - particularly our radiation protection animations. However, I am pleased to report that things are moving again and we recently released some new ‘linac bunker' related training material (featured below). We have new stuff in the pipeline including industrial radiography bunker animations and some resource on recent industrial radiography accidents (more news about this to be released in this blog soon).

Risk Perception



Regular readers of this resource will know I am quite interested in risk perception - something that is very evident when working with ionising radiation. It has interested me somewhat in the unfolding events regarding volcanic ash. I have had my own travel plans disrupted by ash and have closely followed the media and its reporting style. I recall there have been two specific stages where the allowable concentration of ash has been increased - I believe the current limit is 4mg of ash per cubic metre of air. Whilst there is obvious public concern, I have been interested to observe that there appears to be a general acceptance of these levels by the public - I guess they want to ensure they can still go on their summer holidays!?



The interesting thing to note is their acceptance of the regulatory authorities' view that the level of ash is ‘safe'. I wonder if the same acceptance would be afforded if the nuclear industry were to suggest doubling of their emissions from major establishments (on the basis that the new levels were ‘safe'). I am sure there would be a swift backlash - and I cannot help thinking that this is partly because those that protest are not ‘immediately affected' by the limit rise (unlikely 1000's of holiday makers who are potentially affected by ash concentration limits).

This comparison between ash limits and radiation limits can be extended to consider the ‘science' behind those limits. My understanding is that the ash limits (at the extreme end) are based on ‘deterministic evidence' (i.e. where evidence has shown that certain concentrations have shut down jet engines). At the lower end the limits have been set based on ‘discussions' between airlines and their engine manufactures. There certainly has not been enough time to carry out a rigorous analysis of the ash concentration in order to define a limit that comes under the concept of ‘as low as reasonably achievable'. However, despite rigorous analysis of similar concepts related specifically to ionising radiation exposure, there appears to be no improvement in the general public's view with respect to radiation safety. It seems that volcanic ash will always be more palatable than ionising radiation exposure (despite average natural exposures being significantly larger than average occupational exposures!).

If the Icelandic volcano was to really start spewing its content, I wonder how far ash concentration acceptance would go before the general public said ‘enough was enough'. I believe it might be subject to the concept of Stochastic Effect (and therefore related to an acceptable risk ...). Or ... would it be related to Deterministic Effects and related to a threshold effect (we know that 2000 mg of ash per cubic meter of air WILL stop jet enginers!).

Observations on the Chernobyl Disaster and LNT



On a similar risk theme I came across this paper ‘Observations on the Chernobyl Disaster and LNT' by Zbigniew Jaworowski (Central Laboratory for Radiological Protection - Poland). For those that have a problem with the LNT (linear nonthreshold hypothesis), this paper is a dream and is clearly well written with succinct descriptions of the evidence. The abstract is as follows:

The Chernobyl accident was probably the worst possible catastrophe of a nuclear power station. It was the only such catastrophe since the advent of nuclear power 55 years ago. It resulted in a total meltdown of the reactor core, a vast emission of radionuclides, and early deaths of only 31 persons. Its enormous political, economic, social and psychological impact was mainly due to deeply rooted fear of radiation induced by the linear nonthreshold hypothesis (LNT) assumption. It was a historic event that provided invaluable lessons for nuclear industry and risk philosophy. One of them is demonstration that counted per electricity units produced, early Chernobyl fatalities amounted to 0.86 death/GWe-year), and they were 47 times lower than from hydroelectric stations (~40 deaths/GWe-year). The accident demonstrated that using the LNT assumption as a basis for protection measures and radiation dose limitations was counterproductive, and lead to sufferings and pauperization of millions of inhabitants of contaminated areas. The projections of thousands of late cancer deaths based on LNT, are in conflict with observations that in comparison with general population of Russia, a 15% to 30% deficit of solid cancer mortality was found among the Russian emergency workers, and a 5% deficit solid cancer incidence among the population of most contaminated areas.

The paper can be downloaded from the following link: Chernobyl & LET

(The above link will take you to the main page, to read the paper just enter 'Zbigniew Jaworowski' in the search box and then download the paper for free). 

The paper is hosted by the International Dose-Response Society website - this website deals with hormesis (a dose-response relationship characterized by low-dose stimulation and high-dose inhibition).

I am not an advocate of hormesis in ionising radiation exposure (not enough data) and I do not think LNT can be dismissed out of hand (there is plenty of evidence over many decades to suggest that this relationship is plausible). Furthermore, international recommendations and local legislation applies dose limits that must not be ignored - over time these may be amended but for now they are the law.

Medical Radiotherapy Bay - Training Resource



As noted above we have finally got some of our new linac radiotherapy bay resource released. This resource was originally conceived as part of a bespoke radiation protection course incorporating a shielding design module. What you see below is a 3-d walk through ‘a typical' radiotherapy bay - key features included are the shielding design (primary and secondary), active signage, last person out and confirm buttons, emergency stops and cameras.

To compliment this training we have also included some resource by the OU which shows an actual guided tour though a similar bunker.

 

The OU resource which is clearly related is shown below:



Cosmic Radiation and Se-75

Some of you might think I have a hang-up regarding cosmic radiation since I have written about this on several occasions - I do not. I accept it exists and that the UK Ionising Radiations Regulations 1999 (IRR99) does not include it as an occupational hazard. However, despite using cosmic radiation exposure as a comparator when looking at occupational exposures, there is nothing quite like sitting ‘in it' and taking some measurements to really reinforce the point.

I am aware that the monitors I use are not ideal but it is interesting to note that since I have been taking measurements the values have been consistent across a range of detector types (NaI, ion chamber and GM) - and they are similar to reported values too.



So, I set off yesterday for a 1 hour flight and recorded a peak dose rate of 6 micro Sv/h and 37,000 feet. Taking into account the climb and descent, my EPD accumulated value of 3 micro Sv was about right.

Upon arriving at the client site we rigged up a 10 Ci (370GBq) Se-75 source for some scatter profile measurements for a new open top industrial radiography bay (this bay is massive in plan and 5m high). Part of this process involved ‘stressing the bay' - this is my slang for setting up unusual and rare (and indeed normally non-compliant) situations to provide dose estimates to a critical person outside the bay. Instantaneous dose rates ranged from 1- 10 micro Sv / h (this varied with height and with distance from the bay external shielding wall). At ground level maximum dose rates were 5 micro Sv/h - similar to that experienced at 36,000 (but of much lower energy).

The average length of the shots was 11 seconds - therefore whilst the instantaneous dose rates were higher than background, the value of microSv-in-any-one-hour was much lower. Indeed, at ground level we determined that at full pelt the bay could not be used more than 30 times in any one hour - leading to an accumulated exposure time of about 9% of one hour. Therefore the possible accumulated dose in that hour was 0.45 micro Sv, or about 15% of that received during the one hour flight - this of course can be written as 0.45-microSv-in-any-one-hour. This itself over estimates the exposure by some margin since the instantaneous dose rates described above were worse case rather than those achieved by following best practice.

Explaining these findings to workers on the shop floor who have been watching the measurements needs to be undertaken with care. Using the comparison with flying can be helpful but the ‘unseen' radiation is not always taken as read. Hence the measurements and pictures taken as I fly - showing pictures of instruments in use during a flight, and which can be compared with those used in the bay assessment, can be quite a powerful training tool!

Radioactive Sweets

Oh Yes - fancy Barium Black Cherry, Plutonium Pear, Radium Raspberry Lemonade, Strontium Strawberry, or Uranium Yellowcake? Here they are:



Words fail me - but you can find out more at this link: http://tinyurl.com/2ww8uxg

And finally

My friend outside my office!

 

 

This is taken from the IAEA event log.

The Incident - Contamination of Six Workers (26/05/2010)

(Note: the incident was reported to IAEA 28/04/2010)

 

(France). Six workers participating in the task of unblocking a high activity radioactive source of cobalt-60 (1.25 TBq) were contaminated in Feursmetal premises (Feurs, Loire). The Co-60 source was blocked since May 7 in the guide tube of a gammagraphy device which was located in a hot cell of the Feursmetal company. A first recovery operation was carried out unsuccessfully, on 10 May, under the responsibility of Feursmetal and with the assistance of technical teams of the device manufacturer Cegelec. ASN conducted an initial inspection on 12 May to verify the adequate implementation of provisions for radiation protection. On 26 May, a second operation was carried out by Feursmetal and Cegelec with the support of the French Institute for Radiation Protection and Nuclear Safety (IRSN) which provided specific robots to retrieve and secure the radioactive source. The guide tube section in which the source was blocked had been cut on both sides by the robot but, during this operation, the source was damaged and its content spread. This damage was detected when the robot came out of the hot cell for and triggered the contamination survey. The 6 workers (2 IRSN, 2 CEGELEC and 2 FEURSMETAL) in charge of the recovery operation were contaminated. The workers were treated by the specialized medical unit of the EDF St. Albans NPP for proximity reasons and this unit confirmed their internal contamination (anthropogammametry result : contamination between 50kBq and 100kBq). The level of contamination will be specified by the ongoing radio toxicological analysis, after doses reconstructions. Two inspectors from ASN are on site since May 26 evening. ASN has provisionally classified this incident at level 2 on the INES scale.

The incident log can be read at the following link: IAEA News (You may need to log in as a guest).

Ionactive Comment

Wow something has really gone wrong with this job. Co-60 sources used in industrial radiography are ‘special form' material which means they are robust in all reasonably foreseeable events (i.e. will not disperse their content).

Co-60 sources will normally be constructed using cobalt metal pellets confined within a welded titanium and stainless steel capsule (probably double or triple welded capsules). Therefore in order to create some level of contamination the robot noted in the above incident report must have chopped the source directly.

Even then, I am surprised that a personal intake of contamination has occurred - even a chopped source would, in my view, result in several mangled pieces and perhaps some level of tiny filings or similar (depending how the cut was made). These would generally be insoluble and not directly respirable - even if taken into the body by ingestion I would probably expect them to go through and out the otherside (where they would of course deliver a local dose on their way).

The actual levels of contamination (kBq range) seem quite modest which is also interesting given the specific activity of the source material (i.e. even a very small piece of source would be expected to be highly active).

As always we have limited information - but the fact that the Co-60 source was catastrophically breached, and that this contamination was transferred to the workers reveals a significant breakdown in work controls and planning.

Also, by my simple calculations, the dose rate from a 1.2 TBq unshielded Co-60 source would be about 368 mSv/h at 1m, dropping to 14.5 mSv/h at 5m. Using 5cm of portable local lead shielding would drop these to 26.5 mSv/h (1m) and about 1mSv/h (5m). OK, so these dose rates are still significant from an occupational worker point of view, but I wonder if working on a larger piece of the guide tube outside the cell would have been better? At least then a cut could be made which would not have damaged the source?!

This is taken from the IAEA event log.

The Incident - Member of the Public Overexposure (20/04/2010)

(Note: the incident was reported to IAEA 23/04/2010)

 

(USA). The potentially overexposed individual may have spent a significant amount of time visiting his fiancée who was receiving a temporary implant of Cs-137 and Ir-192 seeds via low dose-rate remote afterloader brachytherapy on April 16-18, 2010. The licensee instructed the patient's visitor to visit no longer than 2 hours in a 24-hour period and to stay behind the bedside shield during these visitations. On Tuesday, April 20, 2010, the Assistant Nurse Manager informed the licensee that the visitor claimed to have spent the night in the bed with the patient on two consecutive nights. Nursing Management personnel are in the process of interviewing staff members that were involved directly with the care of the implant patient to verify that the visitor was in the room overnight with the patient. A preliminary and conservative dose estimate for the visitor is 60 mSv (6 rem) whole body exposure, based on a 16-hour stay time (8 hours each night for two nights) and an estimated distance of 15.2 cm (6 inches) from the sources. Investigation of the event continues.

The incident log can be read at the following link: IAEA News (You may need to log in as a guest).

Ionactive Comment

Hmm - perhaps the wrong source of ‘hot' date?!

The mind boggles I guess when determining the visitor source distance of 6 inches (the report does not specify the area of treatment).

No data regarding the sources is given but they might vary between about 400 MBq and 3.7 GBq for Cs-137 (Ir-192 probably about the same).

I said I would never do politics on this blog. But then again I have done cooking curries, progressive rock music, and theft analysis as well as radiation protection - so why not politics?

Actually, I'm not so interested in this up and coming UK election. I was interested to begin with, and I will vote, but I have lost a degree of faith in politics, the media and the electorate. Firstly, let us be clear that this is a race to the wining line and everyone wants to come first (although since this is not proportional representation it is not a simple linear race with the ‘popular vote' deciding the outcome). Therefore, no one party is going to say to the ‘people' we are totally *$&£^$ (insert appropriate word).

It rather annoys me when the media (TV interviews and the press) continually pester the politicians with questions like ‘tell us what you are really going to do after the election' or ‘what real cuts are you going to introduce' or ‘are you NOT going to increase VAT'. Do they really think they are going to get a straight (and indeed honest) answer?

The same can be said for radio interviews. I am amazed how many people (particularly members of the public) come on the radio to specify their own particular requirements or support for one party (be it NHS, schools, energy or green issues) without considering the bigger picture. Indeed, in one interview there was I believe a Labour supporter who stated ‘I will be voting for Gordon Brown again, since Labour came to power there has been such an improvement in the NHS where I work, we have a nice new clean building and lots more staff etc etc'.

The thing is - where does this person think the money has come from - does it grow on trees? Do they not realise that times have changed (perhaps for good?). It is very easy at this point to bash the bankers (I do like everyone else) and blame them for the lack of money and significant debt in the economy. However, when many (like me) have lived through 10 years of house price rises, reasonable standard of living, nice car (etc) did the population really care what the bankers were doing (right or wrong)? I do concede that there were also people much worse off than myself during that period, but then again, many also made an absolute mint way beyond my wildest dreams.

What worries me about this election is that many are blinded with regards the bigger picture. There have been many hints of ‘hard times ahead' - and each party has blamed the other for the possibility of excessive cuts (which might stall economic repair) or scaremongering. But if you look a little deeper you will see that all the cuts thus far discussed by any of the main contenders are completely and utterly trivial - a total drop in the ocean - insignificant - tiny - etc. When you look at the situation in that context I think you can then see that the individual party manifestos begin to blur together - yes each will say something slightly different about TV licensees for the aged, new jobs for young persons, help for small businesses, things for ‘hard working family', trident and so on. But this is where the point of this blog (and indeed it conclusion) begins. In my view none of these ‘little matters' really matter when looking at the big picture - and that is - we as a country are totally and utterly up to our necks in debt. The majority of the electorate in my view is not going to be dominated over the next few years by the ‘little matters' that one particularly party states in their manifesto. Instead, we are all going to be dominated by something that no party can avoid - and it matters not if there is a hung parliament either - CUTS and increases in direct and in-direct tax.

Of course no party could go into this election and be bold and tell the whole story - but I get a little frustrated that there is so much debate (and indeed excitement ?!) when the end game is going to be the same for every individual in the UK. What if one party had said - we will cut jobs, raise basic rate of income tax to 26% in the pound, raise higher rate of tax for 60p in the pound... etc

I am an optimist so do not belong to the ‘tin hat brigade'. However, I think you only have to look to Greece to see the results of ‘difficult' cuts. I think there will be difficult times ahead with everyone having to consider a rethink of their expectations, rights and standard of living.

So for a radiation related site, you might have expected a comment on all things nuclear? Well, I am generally pro-nuclear but concede the industry has not been at its best in the past. However, I do not even think nuclear issues and energy would sway me one way or the other - I still nuclear issues - as important as they are - are small when compared to the massive changes that are going to take place post - election.

Who am I going to vote for - good question!