More on the Fukushima Reactors

Tales from the Nuclear Age

Copyright © 2011 by Charles Glassmire

 __________________________________________________________

Apr. 7, 2011

More on the Fukushima Reactors

Why is this situation taking so long to control?

          The situation is complicated. Working in a radioactive contaminated site requires caution and constant supervision. In the United States, all worker activity in a radiation zone is regulated by the Nuclear Regulatory Commission (NRC).

(Note: For an account of high radiation work see my earlier blog post in June of 2010, on the Army’s SL-1 reactor incident. Several workers lost their lives in the initial excursion there but this was not a “commercial power” incident since the experimental reactor was operated by the U.S. Army.)

          The NRC has established specific exposure limits for U.S. commercial power radiation workers which must not be exceeded on a yearly basis. If a worker receives a short term dose above the weekly limit, Federal law requires that worker to be removed from all radiation work and placed elsewhere until his exposed time limit passes. The law requires the company to keep detailed exposure records for each worker on a daily basis, and these are periodically inspected. Health Physicists are put in charge of the repair work and specifically limit the amount of exposure each day to keep each worker under his limit for that day.

          Each U.S. worker is required to wear a pocket instrument called a “dosimeter” which is the size of a fountain pen and measures the accumulated exposure to the workers body while in the radiation zone. When he emerges from the zone, the amount of exposure is recorded on his chart. The Health Physicist has legal control of the workers and determines who works, how long they work and who is put on temporary leave to allow the body to recover. New personnel are rotated into the work if too many workers are removed for exposure limits. So the entire work force is maintained below the annual limits which are set at a safe level to show no body harm.

 What about Personnel at Fukushima?

          So to Fukushima: I do not know the relevant Japanese legal requirements on the reactor operator TEPCO, but if the situation reported by the media is accurate, TEPCO seems to be operating under a much less stringent set of rules. In Japan, workers are not necessarily provided with a personal dosimeter. In the weeks before this post, CNN reported that all workers had been evacuated from the site except for a volunteer crew of 50, who remained on the site to do all the work. Its reported their work conditions were sparse, sleeping on metal floors, receiving very little food etc. Some reporters even hinted at a “suicide” group who has chosen to die to save their country. This seems more than a bit exaggerated.

How did the contaminated workers happen?

          What we do know is that only three have encountered serious radiation damage after mistakenly wading through highly radioactive water. These were hospitalized and, while their legs have received damage, there are no reports of their imminent death. In fact, a few days ago the three were released from the hospital. (At this dose level there is also the possibility of cancer onset later in life, but their whole body dose has not been published.) This is the reported extent of endangered human life to date. Three persons injured.

          This incident should not have happened, and seems to be a serious misjudgment by management at the site. These men should not have entered unknown (5 inch deep) water without a prior Geiger Counter check, and should have been equipped with dosimeters – which they were apparently not given.

 What’s the situation now?

          The government and TEPCO are not releasing much information to the press. Reactors 1 thru 4 have probably been ruined by salt corrosion from the sea water. They cannot be restarted safely. The spent fuel cooling pools have been exposed to the air from the Hydrogen explosions and then hundreds of tons of water poured in to cool the rods. The result is that draining water and steam are moving isotopes from these spent fuel rods out through the open roofs into the surrounding area, and down into the underground maintenance tunnels underneath the reactor buildings. This is most likely the source of the amounts of radiation being found on the grounds. No levels are given except for statements like “1000 times background”.       This is not meaningful since background levels of radiation vary considerably around the world. The media, in ominous terms, treats each new announcement of local ground contamination as “… a possible meltdown…”. In reality much of this probably originates from the spent fuel storage rooms since the roofs are blown off, and not from a containment breach. Ultimately reactors 1 thru 4 will have to be buried in borated cement. The land area will be declared a contaminated zone for many years.

          Reactors 5 and 6 seem to have been shut down and suffered few problems from the tsunami. These might be capable of restart sometime in the future, but not until safeguards have been increased, this accident thoroughly analyzed, and power sources protected against tsunami and catastrophic earthquake. 

 Has there been a “Meltdown” as the press keeps suggesting?

          First lets determine what we mean by the term. It has been often misused by the media. The classic description of a meltdown has probably come from the motion picture “The China Syndrome” which was ironically released about the time of the Three Mile Island accident. This movie “explained” that the fuel in a reactor could melt into a puddle and then burn its way through the bottom of the reactor containment and continue melting through the ground until it got to China! An emotionally scary concept which made a lucrative movie! This, even in the absolute worst case could not happen since the core of the planet is already molten with red heat and would absorb such a silly idea. Three Mile Island did have partial fuel melting but did not breach its containment vessel  – i.e. no meltdown.

          In theory it is possible for a mass of fuel to melt its way through the bottom of the (3 inch thick) steel containment, then out of the reactor room (3 feet of concrete) and into the ground below. This is precisely the accident that reactors are designed to prohibit.

          Every new discovery of radiation outside of the reactor is decried as evidence of a “meltdown”. There likely has been partial melting of the fuel rods inside the containment vessels, due to the high temperatures created inside. However I have heard no evidence that there has been a breach of containment in any of the BWR’s 1 to 4. Yes there is radiation being spread from the open fuel storage rooms above the reactors and from controlled venting of the pressure inside the containment vessels. This is of course a very serious situation; but it is just not a complete meltdown.

 Where is the seawater contamination coming from?

          On April 2nd, it was announced that a 9 inch crack has been discovered in a maintenance pool for reactor number 2 which was draining high level water into the sea. The following day this was described as a “5 inch crack”? The opening was located in a 20 foot long pipe in a flooded underground tunnel below the reactor containment. This was probably damage caused by the earth tremor. Workers recently entered the underground tunnel, and working in darkness, have located the crack and filled it with liquid glass and hardener. Latest news says this crack has now been successfully plugged and no further release into the sea is occurring.

          Seawater radiation levels were quoted as “millions of times higher than the legal limit…” .  The next day it became “ten’s of thousands of times…”? This very high radiation reading was most likely from Iodine 131, one of the most radioactive products of fission; it is a major isotope component of reactor fission products (about 3% by weight.) This radiation level will dissipate quickly as 131 I  has a half life of only 8 days i.e. every eight days half the amount present changes into inert Xenon. In the next 8 days half of the remaining again disappears et cetera. So we should expect these levels in the sea to dissipate quickly. In addition, the hugh volume of the sea is diluting the remaining effluent and mixing it into the vast areas of the ocean, which will also reduce its intensity ultimately to background level.

          Sea life can accumulate the Iodine it swallows from the sea and can become a health hazard to the thyroid if eaten. Here Potassium Iodide pills (the “Iodine pills” you hear about) could be taken by persons to safeguard against uptake*. It should be noted that radioactive 131I is often administered medically for treatment of thyroid adenomas, and Graves disease. Hopefully regulations will prohibit fishing in the local area for quite some time. Fish markets should check their products for traces before sale…  

(to be continued …)

___________________________________________________

* In an emergency, don’t expect the government to give you these pills. There just ain’t enough to go around. Potassium Iodide pills (Thyrosafe) can be purchased at low cost in the U.S. from a website:   

              http://www.KI4U.com

 

Advertisements

2 Responses to “More on the Fukushima Reactors”

  1. Ellie K Says:

    This is a very sane and balanced assessment of the situation as of the date it was written (8 April 2011). What a relief to hear that ridiculous “China Syndrome” movie based myth put to rest!

    (Was Jane Fonda in that movie?)

    Regardless of how one feels about nuclear power, that silly movie irked me for years, as the fuel rods could not possibly burn a tunnel straight through to somewhere, not even China. Yet it is lodged forever in our popular culture, being such a dramatic image.

    One can be pro- or against nuclear energy and use facts to support one’s viewpoint, rather than perpetuating “China Syndrome” stories.

    Also, everyone can’t be an expert in everything. For several days in late March, radio-active isotopes I 131 was being confused with I 137, where the former has half-life so much shorter than the latter. Meanwhile, others in the press or Twitter-verse were confusing I137 with the Cs137 of Chernobyl (although there was that too, later, I think), and confusion was rampant.

    This is a nice post. Quite unbiased and balanced. I just finished writing an article on a similar topic myself!

  2. My Blog Says:

    whoah this weblog is fantastic i love studying your posts.
    Stay up the good work! You understand, many individuals
    are hunting around for this information, you could help them greatly.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s


%d bloggers like this: