Radiation protection/ effects of radiation

[Astronuc]

FYI -
Consolidated Guidance: 10 CFR Part 20 — Standards for Protection Against Radiation (NUREG-1736)
http://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1736/


I expect there are lots of questions about radiation effects and radation protection. So please post questions or information here.


FYI - http://www.new.ans.org/pi/resources/dosechart/

Health Physics Society - http://www.hps.org/
http://hps.org/fukushima/

 

[Reno Deano]

Some current thoughts on the radiological protection aspects of the Japanese reactor accidents:

INEL: http://www.idahostatesman.com/2011/03/17/1568997/inl-chief-looks-past-hysteria.html#"

IAEA: http://www.iaea.org/press/"

World Nuclear News: http://www.world-nuclear-news.org/RS_Progress_by_on-site_workers_1703111.html"

I will try and answer questions regarding radiation protection activities and risks associated with the recovery operations at the Japanese plants, as best as I can do. ASTRONUC is a very good mentor and source of information also.

Dean Chaney, CHP
37 Years in the Nuclear Industry (Navy, DOE, NRC, Reactort/Facility Decommissioning Consultant)

Remember I am get old and details in my mind are fading.

 

[TCups]

Could you provide some general comments on the quality of radiation radioactive contamination pertinent to the Fukushima events? I am not sure about the relationship of Sieverts and absorbed dosages of alpha, beta, gamma. Comparing exposure from nuclear accidents to absorbed dosage from diagnostic X-ray photons is apples to oranges, isn't it? Internal (ingested) exposure of radionuclides is a whole different set of risks and radiation injury than exposure to external x-ray and gamma radiation. It seems to me that most don't understand the difference and implications.

 

[Reno Deano]

Here is a video released yesterday involving one of the most highly respected radiation exposure and health experts (Dr. Marvin Goldman, UC Davis University of California in Dixion, CA), concerning the detection on radionuclides in California and the release of radioactivity from the Japanese reactor plants:

http://www.kcra.com/video/27184378/detail.html"

Dean Chaney, CHP

 

[javadave]

Here is a video released yesterday involving one of the most highly respected radiation exposure and health experts (Dr. Marvin Goldman, UC Davis University of California in Dixion, CA), concerning the detection on radionuclides in California and the release of radioactivity from the Japanese reactor plants:

http://www.kcra.com/video/27184378/detail.html"

Dean Chaney, CHP

I thought the spent fuel pools were the biggest concern at this point, yet he doesn't even mention those.

 

[Reno Deano]

This IAEA release backs up the premise that core fission products of any significant magnitude (other than Iodine) have not been release from the reactor vessels. Iodine and other Halogens are a fuel rod gap release product that is routinely released from a BWRs into their off-gas system for decay/filtration and release via the tall stacks seen in the pictures. Since the off-gas system were inoperable during to plant black out, venting was by natural convection through the secondary containment. Since the weather shield and pressure control vents/louvers in the top of the containment were not open, the radioactive gases, including a significant amount of hydrogen accumulated in the space and exploded. This action release the radioactive gases into the local atmosphere on and off-site of the reactors. More than likely the spent fuel pools are the current major source of radionuclide's and gases being released from the plants.

http://www.iaea.org/press/"

Dean Chaney, CHP

 

[Reno Deano]

Could you provide some general comments on the quality of radiation radioactive contamination pertinent to the Fukushima events? I am not sure about the relationship of Sieverts and absorbed dosages of alpha, beta, gamma. Comparing exposure from nuclear accidents to absorbed dosage from diagnostic X-ray photons is apples to oranges, isn't it? Internal (ingested) exposure of radionuclides is a whole different set of risks and radiation injury than exposure to external x-ray and gamma radiation. It seems to me that most don't understand the difference and implications.

You question is very scientifically broad and difficult to put into layman's terms for the audience. However, Sieverts is absorbed dose in tissue (dose equivalent). See the difficulty, now I have to explain dose equivalent, which is a away of equating whole body exposure and internal exposure. Biological damage is primarily based on the rate and time of exposure (dose) and the organ of exposure. Dose rate alone cannot determine the true biological effects, and then not all doses produced the same effects per person. The same effects are generally noted only at extremely highl levels of dose equivalents (several Sieverts). However, the spent fuel process/weapons plant worker in Russia also should latent effects not expected for their ultra-high exposres to highly radioactive effluents from the plants. Dr. Marvin Goldman has written some papers on these cases.

For the most part, reporting agencies report dose equivalents for external gamma exposure to the whole body. All emergency action levels are based on external gamma radiation exposure and specific radionuclide concentrations in the air.

Unless you are within a highly contaminated zone with irradiated reactor wear products or areas coated with residual reactor coolant containing fission fragments, Alpha and beta exposure is less of a concern, and then only to the largest body organ (skin) and eyes. Any internal uptakes of such radioisotopes will be evaluated as Dose Equivalent then.

Sieverts are equivalent to REMs (Roentgen Equivalent Man) and Grays are equivalent to RADs (dose to materials). A quality factor is used to convert Grays to Sieverts.

The levels of radiation reported offisite are not significant in the big picture of personal radiation exposure or expected to produce any long range harmful effects to the public.

Those within the confines of the plant will be exposed to the radionuclides boiled off from the spent fuel pool, gamma shine from the spent fuel elements coming directly out of the pools (all combine pools), coolant waters with in pipes that also contain fission fragments from the degraded core, etc. Their dose equivalent (direct gamma exposure and uptake of various radionuclides (should be minimal due to the use respiratory equipment) are combine to control their exposures during emergency work.

When working in such an atmosphere of radionuclide gunk, the use of good respiratory equipment and protective clothing all controls to focus on whole body absorbed gamma dose to control overall dose to responders. It gets very sticky if uptakes and encountered and then directly dependent on the specific radionuclide.

Sorry about not getting into radiation biology, but it is very difficult subject and only worthy of non-hypothetical and very specific situations. Our cells are assaulted every minute of the day by high and low energy penetrating radiations, since time immortal. Some populated areas of the Earth have background radiation levels (airborne Radon and terrestrial gamma) 10 time higher averages than found in most US population centers.

Typical Radiation Protection Information:

http://www.nrc.gov/about-nrc/radiation/rad-health-effects.html"

More Detail Radiation Exposure infomation from HPS:

http://www.umich.edu/~radinfo/introduction/needtoknow/lstpart2-3.htm"

Dean Chaney, CHP

 

[TCups]

Is it generally correct that the population at large, outside of a reasonable perimeter from the accident site, need not worry about gamma radiation, but instead, should worry about contact with airborne (or otherwise transported from the accident site) radioactive contaminants (in dust and foodstuffs) with a relatively long half-life, with either alpha or beta ionizing radiation, and in particular, ingesting or breathing same?

 

[Astronuc]

Japan cites radiation in milk, spinach near plant
http://news.yahoo.com/s/ap/as_japan_earthquake

Fukushima water tested above safe limit 2 days ago (on March 17)
http://news.yahoo.com/s/ap/20110319/ap_on_re_as/as_japan_earthquake_water

The original source of the milk and spinach will have to be identified and tested.

While the levels are low, such that they may not threaten health, they are nevertheless above normal limits, and the radioiodine should not be there (obviously).

 

[Bob S]

FYI -
Consolidated Guidance: 10 CFR Part 20 — Standards for Protection Against Radiation (NUREG-1736)
http://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1736/

This page (see attachment) from the above 10 CFR 20 states the annual occupational dose limits in rems (with Sieverts shown as an alternate). Why not just use rems?

Medical radiologists are now using cGy (centiGray) instead of rads. 1 cGy = 1 rad. Makes things easy. Why don't we introduce a new quantity cSv (centiSieverts). 1 cSv = 1 rem. Then we can get back to the universal rads and rems that have served us well for half a century.

Bob S

 

[Reno Deano]

Thoughts concerning contaminated food stuffs. Non-technical thoughts: The Japanese island was bombed with a dirty and a hydrogen nuke in the forties (I believe). Much of the debris has been washed into the oceans surrounding the island over the ensuing years. Now a Tsunami has washed over the land. I wonder what their baseline values have been previously for environmental monitoring, considering the past radionuclide contamination of the island areas. The current levels of iodine is definitely from the reactor plant venting, but the uptake is curiously very fast for plants. Must be surface contamination values. As for iodine in the milk it could be cross contamination from handling of the milk at the source and not the cows uptake. I am pretty sure there is a lot of residual cesium on land and off shore of Japan.

Any thoughts on the rise in off site plant and milk contamination, even though it is minute?

 

[Reno Deano]

I was wonder where the NRC got the 50 mile evacuation recommendation from! It was not from real data but typical Hypothetical computer calcs.

Talk about doom and gloom being foisted on the public:

http://www.nrc.gov/reading-rm/doc-collections/news/2011/11-050_Attchmt.pdf"

Sure would like to see actual airborne radionuclide concentrations measured.

 

[minerva]

I was wonder where the NRC got the 50 mile evacuation recommendation from! It was not from real data but typical Hypothetical computer calcs.

Talk about doom and gloom being foisted on the public:

http://www.nrc.gov/reading-rm/doc-collections/news/2011/11-050_Attchmt.pdf"

Sure would like to see actual airborne radionuclide concentrations measured.

KEK in Tsukuba is measuring and reporting airborne radionuclide concentrations.

http://www.kek.jp/quake/radmonitor/GeMonitor2-e.html

(Air samples from a high volume air sampler, with the filters analysed via gamma spectroscopy with a HPGe detector.)

Most of those fission products are present at nanobecquerels per cubic centimeter.

You can see how the amount of the very short lived fission product ¹³²Te has been decaying over time, which does indicate that yes, it really is fission-products entering the atmosphere from the Fukushima reactor.

It's definitely from an actual reactor and not from the used fuel pool because used fuel in the pool doesn't contain the short-lived fission products, they have all decayed away.

 

[Reno Deano]

Here is a some what up-to-date comprehensive paper on the Nuclear Fuel Cycle and Radiation Exposures from the IAEA:

http://www.world-nuclear.org/info/inf05.html"

Dean Chaney, CHP

 

[Astronuc]

How many mR/hr (alpha,beta,gamma,or x ray) could be considered unsafe for continuous exposure?
http://www.hps.org/publicinformation/ate/q349.html

Toxicity of uranium

Uranium, as you know, is a heavy naturally occurring metal that is found just about everywhere in nature. Although radioactive, it has a very low specific activity (i.e., the amount of radioactivity per gram) and thus, being a heavy metal, is considerably more hazardous from the standpoint of chemical toxicity. Indeed, for natural uranium the chemical toxicity is the overriding consideration and is approximately the same as the chemical toxicity of lead.
. . . .

http://www.hps.org/publicinformation/ate/q450.html

Health effects of uranium
http://www.hps.org/publicinformation/ate/q754.html

Effects of Alpha emitters
http://hps.org/publicinformation/ate/cat57.html

Effects of Pu
http://hps.org/publicinformation/ate/q1339.html
http://hps.org/publicinformation/ate/q1053.html

 

[Astronuc]

From the Centers for Disease Control and Prevention, some useful information.

Emergency Preparedness and Response / Radiation

http://www.bt.cdc.gov/radiation/