Pu-238 Dust Mitigation with HEPA filters

GoogleNaut · Guru

Pu-238 Dust Mitigation with HEPA filters

Dusty · Veteran Member

Seems to me from reading through this and other posts concerning Pu238 production that the main problem is that we do not manufacture enough.

If demand and consumption were larger than it would be worthwhile building modern production and processing facitities. Since demand is small, we are having to get by using aging reactors and manufacturing plant.

As for pacemakers (mentioned elsewhere) If I ever needed one i would *far* rather have a Pu one that one with a rechargeable battery. "Death by flat battery" doesnt really appeal

Also, re filters. There are plently of facilities dealing with airborne material that is, pound for pound, far more lethel than Pu238 (and much more dificult to detect, at least the Pu *is* radioactive, so you know where it is) consider Ebola, pnumonic plague etc How do those filters work? (I suspect that biolabs use a mix of filtration and active steralisation-but I dont know for sure)

Dusty

10kBq Jaro · Senior Member

Dusty wrote:

Seems to me from reading through this and other posts concerning Pu238 production that the main problem is that we do not manufacture enough. ....we are having to get by using aging reactors and manufacturing plant.

Right. If we were manufacturing enough, we wouldn't be buying it from the Russians.

Personally, I was pretty upset when DoE decided to permanently shut down its FFTF reactor, which would have been a better producer of Pu-238 (and other isotpes) than ATR, and would have allowed uninterrupted development of advanced fast neutron reactor technology, such as is required as part of the Generation IV nuclear power plant development program. Instead, DoE is paying France top dollar to run some irradiation experiments at its Phoenix fast breeder research reactor. Go figure !

Still, having done this stupid thing, the fact remains that the ATR can certainly be used to produce Pu-238 safely. Being an open-pool type reactor, there is really very little in it that experiences safety-related aging, other than the fuel itself, which gets periodically replaced, as it burns out.

stungun · Veteran Member

Hi all,

RE:Assuming a typical quality HEPA filter has 99.97% efficiency, this means that in general it will pass 0.03% of particulates. So in this worst-worst case with heavy dust suspension:

Well, it is admirable to check out pu-238 filter dispersion, this is the most flawed assumption, Mr GoogleNaut. Given that it is part of the DOE/NRC Bible, I never had the "Faith" required to Believe, so I have asked for proof during my 17 years investigating. The death is in da details...

Let me share the paper I submitted to the Natl Acad of Science panel on "Research needs for TRU waste management" that led to their recommendation for "emission free treatments. I give the NAS icon and quote below the paper.

The short version of the paper below is twofold-

1) The HEPA filters bragged 99.97% filtering efficiency is for 0.3 micron particles AND LARGER. The efficiency for smaller particles is unknown, as is the % of effluent that is actually below 0.3 micron. I cite the Horn experiment where 100% of the pu from a criticality experiment are ALL below 0.3 micron in size.

2) The "alpha recoil" problem is NEVER addressed when DOE states such high efficiency, then reduces effluent figures tri-fold with three filters in a row. In 1970 DOE's McDoweel verified alpha emitters knock themselves loose from filters and creep through at least the 4 HEPA filters in a row he experimented with. Pu-238 should do this 275 times faster than pu-239, but DOE refuses to investigate this SHOW STOPPING problem, despite this NAS advice, and the court ordered Alternative to Incineration panel advice (after my testimony).

I paste the paper below, where the filter flaws come first, but it is followed by my DOE documents on the pu water transport problems, that totally blow away the old DOE promise that pu never moves with water...

To the NAS panel on Development of "Risk-Based" Approaches for Disposition of Transuranic and High-Level Radioactive Waste,
     I needed to share some vital information on HEPA filter problems and plutonium transport in water that effects risk analysis of most alternatives to treating disposal of TRU and high level waste. I am a podiatrist in Twin Falls , Idaho. As a citizen, and as a member of the CDC advisory panel on INEEL, I have gathered some vital documents on HEPA filter problems and Pu transport problems .
I hope your panel will address these issues that DOE is ignoring.
   I will document that, presently, incorrect air releases are used for risk analysis of treatment and retrievable containment structures for TRU waste.
I will also document that leaving TRU waste buried, and also re-burying TRU waste, are using incorrect water transport figures for risk analysis.
   Let me first address the simple solution to the problems first, as your mission also calls to examine "potential alternatives to geologic disposal for disposition of low-hazard waste."
   It is listed as "alternative 5" for INEEL's Record of Decision for the buried TRU in our Pit 9. This alternative simply rebarrels the waste and stores it above ground in retrievable, inspectable buildings.
   For the buried TRU I want to solidify the waste first to avoid airborne plutonium dust. Techniques like injectable cement would greatly reduce the airborne exposure of the present plan to use a backhoe.
   The Pit 9 ROD dismissed alternative 5, claiming it would "pose a potential radiological hazard to the workers, the community, and the environment." When I asked for that risk analysis, they admitted in the ROD they had none because "it was too theoretical to analize." HMMM.
   The TRU incinerator EIS also dismissed a similar alternative A.5 for questionable risk as well. This time (page F-6) , the DOE claims a "geological disaster is expected in the next 55 year time frame." They refused to share that analysis after I questioned why the say the geology at INEEL is safe for bringing in high level spent fuel rods and building 3 new commercial nuclear reactors here ( Nuclear Power 2010.) Perhaps you could shed some light here in Idaho.
   If the data shows we are on a dead end road trying to sweep away this waste, don't be afraid to put on the brakes and just safely contain this waste above ground. CONTAINMENT is the key word. Now to document the detailed problems.
     The HEPA filter issues really effects almost all nuclear projects.
Please contact me for more details if desired, but here is an overview.
   To get an air quality permit, the project has to show they do not
expose the public to more than 10 mrem of radiation from normal
operations (and my memory says that there is a 100 mrem limit to
anticipated accidents).
    The filters are bragged to be 99.97% efficient for 0.3 micron
particles, and more efficient for both smaller and larger particles.
This allows them to calculate a very low rate of release, qualifying
easily for a permit.
   Here are the 2 main areas of filter problems, that remain
unquantified. I have called for testing the filters, in lab, for these
problems, at all so-called Environmental Impact scoping hearings. To
date, these questions have remained unanswered.
   1) Most folks know that the filters can burn, but even if the fire is
contained and put out by sprinklers, that humidity can ruin the filters.
The DOE's May 1999 Defense Nuclear Facilities Safety
Board(DNFSB/TECH-23) had this to say, on page 2-5, " When installed fire
suppression systems are activated to protect systems, structures, and
components inside confinement, the moisture-laden air carried downstream
to the HEPA filters can seriously degrade filter preformance-at a time
when high-efficiency filter performance is crucial." All this is
"despite the fact that water repellents are applied to the medium during
manufacturing." This does not stop the DOE from saying that the 3 HEPA
filters in a row combine for 10 to the minus 9th power filtering
efficiency (99.9999999999%).
    Criticalities (not in report) are also another unquantified
accident, that could be quantified truthfully in lab settings. I have a
great DOE paper from an FL Horn, replicating a criticality with
plutonium. On day one, the particles were between 0.1 micron down to
less than 0.005 micron. Plutonium is a heavy metal, and often a wind
resuspension factor of 1 per million particles is assigned in the EIS.
In this FL Horn experiment, the plutonium particles were so light, that
in this windless closed cell, they floated for 3 days , bouncing around
on the brownian motion of the air molecules! They slowly aggregated and
precipitated, but that was in this closed cell.
   2) "Alpha recoil " is a DOE term, for the ability of alpha emitters,
like plutonium, to "creep " through 4 HEPA filters in a row! Nobody
knows how much plutonium comes out of the last filter. We need to make
the DOE reveal the plutonium releases for normal operations, in a lab.
   The DOE has known of this problem since the 1970's, but has chosen
to ignore it. I have 2 papers from DOE on this. One is from WJ McDowell,
from Oak Ridge. For the 14th ERDA Air Cleaning Conference, he writes a
paper called " Penetration of HEPA filters By Alpha Recoil Aerosols."
He says "Tests at Oak Ridge National Laboratory have confirmed that
alpha-emitting particulate matter does penetrate High-efficiency filter
media, such as that used by HEPA filters...Filter retention efficiencies
drastically lower than the 99.9% quoted for ordinary particulate matter
were observed with Pb-212, Es-253, and Pu-238 sources, indicating that
the phenomenon is common to all of these..."
    It seems as if the alpha particle, from the radioactive decay,
literally knocks the particles loose. As it creeps through any filters
that is in it's way, the DOE thinks that smaller pieces of the
plutonium particles, break off the original particle, increasing the joy
of downwinders.
   Another DOE paper comes from Arthur H Biermann, at Lawrence
Livermore, from Dec,11,1991. His paper is called,"Alpha migration
through Air Filters: A Numerical simulation." He says ," It is obvious
from the review of the literature that evidence exists of the migration
of alpha radionuclide species through high efficiency filter media."
    Both papers have many DOE references, and both call for quantifying
the true releases , in lab experiments. The experiments are do-able,
but, so far, the DOE ain't gonna do it.
     I have asked for Dr Liu, at the University of Minn. to be
commissioned to study these issues. He uses a "total capture" technique
for downstream particle counting. This is key to true efficiency
detection ,or lack of. The present laser counter can detect down to 0.1
microns.
Dr Liu can go to 0.007 micron. Seems the minimal efficiency size goes
down from 0.3 micron, each time particle size detection ability
increases...
      The FL Horn experiment I mentioned replicates a criticality, and
has Pu under the electron microscope. It ranges, on day one, from 0.1
to
LESS THAN 0.005 micron, a bottomless scale! The Pu
particles slowly aggregate, but much was still floating for THREE DAYS
on the brownian motion of the air molecules, in this closed cell
experiment. We need to quantify normal and accident filtering truefully,
for the first
time in nuclear history, and we should use this panel to do it.
    The DOE Beirmann paper mentions, as a theory, that the bigger
pieces of Pu, that get caught in the first filter, may break off smaller
pieces via this alpha recoil. That throws another flaw in the true dose
to the
public during normal operations, over 30 years. This effects all nuclear
facilities,
past and present.
    While the DOE ignores this, a recent study was conducted in the UK.
Y. Yamada et al published "Re-entrainment of 239PuO2 particles captured
on HEPA filter fibres." (Radiation Protection Dosimetry Vol 82 No 1,
pp25-29,1999 ).   While I will present what I think are the shortcomings
of the
Yamada study, they clearly acknowledge the true efficiency of Pu
filtering has NOT been quantified before. However, Yamada reported two
different
resuspension rates. The higher, dust loaded rate was a staggering
resuspension
of 1 particle per hundred per hour!
Firstly, it is significant that the Yamada study on the re-entrainment
of PuO2, detected a PER HOUR rate of Pu resuspension. There is
not supposed to be a PER HOUR rate of resuspension, of any kind. The
DOE permit applications state that 99.97% efficiency is the MINIMUM,
PERIOD.
This qualifies them to claim that the 10 mrem limit to public exposure
will not be exceeded. This appears to be drastically contradicted by
the continual plutonium resuspension rates, especially at higher dust
loading , which replicates historical use of filters left in place for
decades. Note p.28 states," For example, the dispersion rate at twice
dust loading was calculated to have increased by 13 times. It was
confirmed that re-entrainment was strongly affected by dust loading."
   My main criticism is that the experiment only lasted 20 days. The
paper , ironically, does site and acknowledge, the 1976 McDowell
paper I love. That McDowell paper notes that regular testing missed the
alpha creep because of the short duration of their testing. McDowell
left his test up for one year.
    The Yamada test , however, seems to have enough sensitivity to
detect alpha creep, at all flows, even in this limited 20 day
experiment.
   I question their conclusion #1, which dismisses the lower rate of
re-entrainment. They conclude, " Therefore, it was concluded that
plutonium particles captured on fiber filters near the front surface
hardly penetrate the filter."
    I believe their dismissal misses the red flags I see. In a mere 20
day experiment, it is noteworthy that ANY plutonium gained full
penetration of this filter, at this low rate. As McDowell notes, a
longer time frame reveals more alpha creep. This 20 day experiment
is unrealistic, since no where in the DOE are HEPA filters changed
every 20 days. This low rate, short run, underestimates the true, long
term penetration by alpha emitters.
   I noted Yamada's reference 4, the Fliescher study , that supports
the probable fragmentation of smaller plutonium particles, from the
larger
original plutonium particles. This is the Bierman paper's theory , as
well.
   This clearly calls for Dr Liu's ultrasmall, ultrasensitive "total
capture" technique, to capture ALL sizes of particles, to be done over
an extensive period of time, that replicates actual normal use. How
else are we going to determine the true efficiency, of this documented
alpha creep problem?
     Three important points come to mind. 1)Do the other beta and
gamma emitters, that are impacted on the filter, with the alpha
emitters, also leave the filters undetected? Does that not require
further testing?
2) Do more radioactive alpha emitters, like the Pu-238, have even
higher rates of resuspension? Does this not call for more testing?
3) Since this Yamada paper confirms alpha creep, why have the
DOE downstream monitors not detect any whispering of this plutonium,
through the filters? The CDC swears that the monitoring proves their is
no alpha creep "footprint" on the monitors, declaring their faith in the
monitors. I believe the phrase , "below detectable limits", applies to
the downstream monitors, and their inability to reveal the true
exposure to the public, of inhalable alpha emitters.
     The second issue is the recent discoveries by DOE revealing
plutonium transport in water is much easier than previously believed.
This is
also being ignored by the DOE.
The nuclear facilities at the Idaho National Engineering and
Environmental Laboratory have left a legacy of radionuclides,
including plutonium, in shallow land burial. These burial pits have
been flooded, and sit over the Snake River Plain Aquifer. Now, the
Department
of Energy, with the blessing of the State of Idaho, and the
Environmental
Protection Agency, have approved a new shallow land burial pit,
which although it will have 2 plastic liners and monitors, will also
have billions of plutonium particles which remain radioactive for about
240,000 years. Some plutonium particle clean up projects may
simply leave the plutonium buried, but cover it with more dirt and
plastic, called "capping."
     The RWMC has a buried mixture of TRU and alpha low level. I hope
the NAS will address ALL of the plutonium particle waste, not just the
official TRU.
   The standard of 100 nanocuries per gram of waste material was created
in 1984. By raising the definition of TRU tenfold, the DOE
reclassified almost half the waste to low level, allowing the leaving or
reburial on
site. Maybe coincidently, it also saved WIPP from being overfilled
before it
opened. I have transcripts from the meeting that changed the standard.
The
reason given to justify the change was a calculation that the 100 nano
standard
would give an acceptable dose of 500 mrem from animal intrusion and
resuspension
     This definetly ignores the water pathway in Idaho. More important,
it ignores the total quantity of plutonium which will be left over our
water.
    For example, the Pit 9 ROD reburies it's one acre at a seemingly low
limit of 10 nanocuries per gram.   At my request, they finally estimated
that represents 3-4 lbs of plutonium. DOE has always refused to estimate
the
number of inhalable plutonium particles in a pound of Rocky Flats waste,
but I believe billions is a low guess. It is important to think through
the final waste legacy, since we have 88 acres of buried Rocky Flats
waste.
It is estimated that 2700-3200 pounds of plutonium lay in these burial
sites,but the real amount is unknown.
    The new ICDF dump uses the 10 nano curie standard, but for 8 acres
this time.Using the Pit 9 estimate, that's another 24-32 pounds of
plutonium
particles.
How much plutonium would you recommend to rebury over our water? What if
it was your water, and your pregnant wife?
    The final WIPP EIS chooses to leave ALL the buried waste in Idaho.
It alsochooses to leave half the above ground waste that is below 100
nano.
    The 1995 EIS for INEEL says they may open a 200 acre low level alpha
dump on site, and may bring in all the DOE waste, not just ours.
     These decisions to open a new plutonium dump, or cap plutonium
where it has leaked, are only required to try to calculate radiation
doses the public, in a thousand year time frame, if it is below 100
nano/gram.
Unfortunately, as mentioned , the plutonium particles, which are
potentially deadly and cancer causing, if inhaled and embedded in your
lungs, remain
radioactive for over 240,00 years.
     Much of the Snake River Plain Aquifer is pumped to the surface
for irrigation or sprinkle irrigation, which would make the plutonium
available for resuspension and inhalation.
    We have been told for years that plutonium is an actinide, that
binds to clay and rocks, immobilizing the plutonium, protecting the
aquifer.We have been told, even in the unlined plutonium trenches
originally used until 1970, that the aquifer was protected by the
sorption property of plutonium, and the insolubility of plutonium.
    These statements and decisions by the DOE , EPA , and State,
have unfortunately ignored two recent , contradictory DOE studies, that
both show how easily plutonium moves with water. Understanding these
important contradictions is key to protecting Idaho's water supply
and public health for centuries to come.
     These two separate studies actually reveal a double trouble
scenario, because both the soluble forms , and the insoluble forms of
plutonium can move with water.
    The A. B. Kersting study , was done at the Nevada Test Site(1).
This study found that insoluble plutonium had migrated 1.3 km
(roughly one mile) bound to clay as a colloid and was suspended and
floating in this sluggish aquifer, 30 years after being introduced to
the
underground environment.
    This is a profound, and dangerous discovery, that should change
our nearsightedness about plutonium over our aquifer.
    These plutonium colloids ranged in size from greater than one
micron, down to 0.007 microns. The DOE acknowledges that
inhalation of plutonium is the most dangerous pathway of human exposure.
Plutonium colloids in our aquifer would be available for inhalation from
the common use of sprinkle irrigation, and even canal irrigation that
later dries, allowing newly surfaced plutonium to be resuspended in
the wind.
    The fact that these are insoluble particles of plutonium, means that
each particle contains millions of plutonium atoms. That makes
inhalation more dangerous because , while the single strike alpha
disintegration of a single radon gas atom is dangerous, an embedded
plutonium
particle provides a point of perpetual radiation and alpha destruction.
   The Kersting paper notes the old thinking of the DOE, siting the
McDowell-Boyer paper. They say , "It has been argued that
plutonium introduced into the subsurface environment is relatively
immobile owing to its low solubility in ground water and strong sorption
onto
rocks."   Kersting notes there are two previous studies of field
observations contradicting that premise (2, 3).
    I have heard the DOE, CDC, State, and ATSDR verbally dismiss
the Kersting study as "due to the bomb testing." However , Kersting
addresses the issue, stating that in the 40 years of bomb testing,
previous testing only found that "radionuclides were detected at a
maximum of a few hundred metres from the original detonation site.
"Having isolated the specific isotope ratio of the Benham bomb test
debris, there is no doubt of its origin. The Kersting team concludes ,
"The possibility that the Pu from the Benham test site was blasted and
deposited greater than 1.3 km away, in two distinct aquifers
separated by 300 m vertically and 30 m horizontally seems highly
unlikely."
    Most importantly, Kersting concludes," Pu transport models that
only take into account sorption and solubility may therefore
underestimate the extent to which this species is able to migrate in
ground water."
    That is one reason why I say that the DOE, EPA, and State are
ignoring their own contradictory studies. The modeling for Idaho's
future does not include the Kersting study on colloid transport of
insoluble plutonium. While we open new shallow burial sites, and
leave other plutonium where it lies, underestimating this plutonium
transport is not acceptable.
    The second study I will refer to, is from DOE's Los Alamos lab,
by John M. Haschke (4). While Kersting showed the mobility of
insoluble plutonium, Haschke revealed that Pu in our environment can
change oxidation states in the presence of airborne water vapor and
become
very soluble in water, enhancing mobility. This discovery contradicts
the present textbooks, according Dr Madic (5) , who wrote the
accompanying "Perspective" , when the Haschke study was
published in Science. Textbook knowledge had only found Pu02 in the
environment, in oxidation states III and IV. Madic writes how this must
affect how we view everything, from the new plutonium laden MOX nuclear
reactors, to nuclear storage. Madic states," Until now, it was assumed
that plutonium would not be very mobile in the underground geological
environment because of the insolubility of Pu(IV) compounds. But Haschke
et al. demonstrate that water can oxidize Pu02 into Pu02+x, in which
more
than 25% of the plutonium can exist as Pu(VI), an ion that is far more
soluble, and thus mobile, than Pu(IV). This new property will have
important implications for the long term storage of plutonium."
      So when will the DOE, EPA , State, and ATSDR apply this
information to protect our water and our health ? We need above
ground, inspectable and retrievable storage for the billions of
plutonium particles dumped over our water. To ignore these studies is
inexcusable.
    There is one more paper I will quote, from Dr Runde.
I went to the Wolfgang Runde article called "The Chemical Interaction
of Plutonium in the Environment." It is from a Los Alamos conference
on plutonium transport. That can be referenced at
http://lib-www.lanl.gov/pubs/number26.htm
      Runde acknowledges the colloid transport was fast, and concludes,
"What is clear is that transport models to date have underestimated the
extent of colloidal transport on plutonium mobility."
      Let me put his conclusion in context, and quote Dr Runde to a
fuller extent.
    Dr Runde, on page 408 (or 17 of 20 on the computer download) says,
" We are also trying to better understand the sorption/desorption
reactions of actinides with colloids and the actinides' resulting
transport characteristics. This area of environmental migration received
attention with the discovery of plutonium in a borehole at the Nevada
Test Site (Kersting et al. 1999). The plutonium had evidently migrated
1.3 kilometers in only 30 years."
    Runde continues," As discussed in the article by Maureen McGraw, we
now believe that colloid transport was responsible for this remarkably
fast movement of plutonium through the water saturated rock. It is not
clear, however, whether the transport was facilitated by intrinsic
plutonium colloids or natural (clay or zeolite) colloids. What is clear
is that transport models to date have underestimated the extent of
colloidal transport on plutonium mobility."
     The only reference to the uniqueness of bomb testing is the initial
time it takes to reach plutonium exposure to water. Runde notes that
the underground explosion allowed the plutonium to be left in water,
while a waste repository would differ, because the "radionuclides would
be isolated, at least initially, from the hydrogeologic environment.".(p
490 )
    Runde also mentions a new concern for Pu migration, and that is
microbes acting as " mobile colloids. "   While they may act as a
barrier, they may aid transport. Runde says, "As such, they act as
mobile or even self propelled colloids. (p 409, 18/20).
    That is another reason we should simply re-barrel the plutonium
waste, instead of shallow burial.
Runde concludes, " More sophisticated models are needed to account
for all the potential migration paths away from an actinide source.
Theoretical and experimental scientists will be challenged for years by
demands of
developing these models.(p 410, 19/20)
     Gee , I look forward to when they finish the job. Why would we
want to rebury plutonium over our water before they understand
plutonium transport in water?
      I look forward to your reply.
           Sincerely, Dr Peter Rickards DPM
                           2672 E 4000 N, TF, ID 83301

1)A.B. Kersting et al. , Lawrence Livermore National Laboratory,
Nature, vol 397 Jan 7, 1999, p56-59.
2)McDowell-Boyer , Environmental Science Technol. , 26 ,
586-595 (1992)
3)Ryan et al, Physiochem. Eng. Aspects, 107 , 1-56 (1996)
4)JM Haschke et al. ,Science 287, Jan 14 2000
5)C Madic, Science 287 , Jan14, 2000
_______________________________________________________

Here is the NAS recommendation for emission free treatments (page 7 of the
report)
http://books.nap.edu/books/0309084717/html/7.html
In the absence of effective treatment technologies, waste is simply
repackaged to avoid the problem. Repackaging waste in order to meet shipping
requirements is extremely inefficient, may increase volume manyfold, and
presents hazards to workers. Phasing out incineration for the destruction of
organic constituents requires the development of alternative technologies.
Wastes classed as unique or problematic- including reactive materials, gas
cylinders, and tritium-contaminated materials-comprise only about 10 percent
of the inventory. They are often overlooked in site cleanup contracts, but
they deserve special attention for research because some will be difficult
to treat and may eventually become roadblocks to site closure. Application
of biotechnologies for treating wastes has been largely overlooked.

The committee believes that the greatest challenges for the next generation
of treatment technologies lie in developing

a.. emission-free treatment processes,

b.. treatments for problematic or unique wastes, and

c.. methods to ensure the long-term durability of stabilized waste.

Opportunities for basic research lie in chemical treatment, biological
treatment, and waste stabilization. For chemical treatment, understanding
the speciation of inorganic constituents, oxide-substrate interactions, and
mechanisms of gas production and adsorption (especially hydrogen) is
fundamental. In the biological area, research should include enzymatic or
whole-cell approaches that target specific or broad categories of
contaminants, biotransformations for removing mercury and heavy metals,
bioaugmentation or biostimulation to remediate actinide-impacted soils, and
development of hydrogen and methane scavengers. In the stabilization area,
research should address new approaches to stabilizing buried waste prior to
or in the early stages of excavation, smart materials that react with waste
constituents, and very long term barriers against contaminant migration and
methods to prove their longevity.

Public concern about air emissions from incineration has created incentives
for applied research toward large-volume, robust alternatives that are
emission free, as well as to smaller-scale, portable devices that may have
specialized applications. There are also opportunities to develop more
efficient processes that yield smaller or easier-to-manage waste streams
from DOE's ongoing activities (e.g., isotope production, generation of
secondary wastes from high-level waste processing, facility deactivation and
decontamination).

iprimap · Veteran Member

As others have pointed out before, mankind routinely uses other substances that are as deadly if not more so than Pu-238. So all the complaints about Pu-238 hazards are simply that - complaints. Properly contained and handled, I would imagine that Pu-238 is as safe as any of the other hazardous, toxic chemicals, compounds and radioactive substances that mankind uses in medicine, industry and power generation. For example, one rail-road tanker full of chlorine can ruin a small town's day, yet these tankers routinely run up and down the populous Hudson Riverbank in Westchester and Rockland Counties with nary a word of protest.

That being said, if the concern is solely the potential hazards involved in using Pu-238, then why not use a different radio-isotope for RTGs? Wikipedia states the following:

http://en.wikipedia.org/wiki/Radioisotope_thermoelectric_generator

The first two criteria limit the number of possible fuels to less than 30 atomic isotopes within the entire isotope table of elements. Plutonium-238, curium-244 and strontium-90 are the most often cited candidate isotopes, but other isotopes such as polonium-210, promethium-147, caesium-137, cerium-144, ruthenium-106, cobalt-60, curium-242 and thulium isotopes have also been studied. Of the above, 238Pu has the lowest shielding requirements and longest half-life. Only three candidate isotopes meet the last criteria (not all are listed above) and need less than an inch of lead shielding to control unwanted radiation. 238Pu (the best of these three) needs less than 1/10 of a inch, and in many cases no shielding is needed in a 238Pu RTG, as the casing itself is adequate.

238Pu has become the most widely used fuel for RTGs, in the form of plutonium oxide (PuO2).238Pu has a half-life of 87.7 years, reasonable energy density and exceptionally low gamma and neutron radiation levels. Some Russian terrestrial RTGs have used 90Sr; this isotope has a shorter half-life, much lower energy density and produces gamma radiation, but is cheaper. Some prototype RTGs, first built in 1958 by USA Atomic Energy Commission, have used 210Po; this isotope provides phenomenally huge energy density, but has limited use because of its very short half-life and some gamma ray production. A single pound of pure 210Po in the form of a cube would be about 3 inches on a side and emit about 63,500 watts of heat (about 140W/g), easily capable of melting then vaporizing itself. 242Cm and 244Cm have also been studied well, but require heavy shielding from gamma and neutron radiation produced from spontaneous fission.

Americium-241 is a potential candidate isotope with a longer half-life than 238Pu: 241Am has a half-life of 432 years and could hypothetically power a device for centuries. However, the energy density of 241Am is only 1/4 that of 238Pu, and 241Am produces more penetrating radiation through decay chain products than 238Pu and needs about .7 inch worth of lead sheilding. Even so, its shielding requirements in a RTG are second in thickness (greater than) only to 238Pu.

Personally, I would prefer a full-fledged nuclear spacecraft perhaps initially modelled on the NERVA design or something similar. But for robotic missions to the outer solar system where sunlight levels are too low to provide adequate electrical energy from PV cells, RTGs make good sense.

Sorry, Dr. Stungun. Pu-238 is ideal for RTGs. Even should we Americans abandon the use of this radio-isotope, other countries such as Russia and Communist China will not. The genie is forever out of the bottle and no amount of wishing or whining will put him back.

GoogleNaut · Guru

I agree with you Paul, but I also have to admit that micro particle migration through HEPA filters could be a problem. The "off the cuff" calculation I did was very simplistic, and I admitted there was a lot I didn't know--such as the true production rate for dust in pellet fabrication--I can't seem to find much information at all about that. So I made some guesses and some estimates--that's all they are.

Mitigation of the finer particles could concievably be possible by scrubbing them from the air downstream of the HEPA filters by using a combination of electrostatic precipitator and possibly an application of humidty--an aritificial precipitation chamber which uses moisture condensing around even the smallest particles to create a fog which moves the particles downward. Sounds expensive and might not even work. I don't know if it's possible to get every last bit out--probably not.

Years ago, PG&E (Pacific Gas and Electric) which operated a small 55-100 MWe BWR at Humboldt Bay Power Unit No. 3 (decommisioned in 1976) used a 200 ft tall tower to exhaust air from a HEPA filter unit connected to the reactor building. About seven years ago PG&E dismantled the tall stack, reinforced the reactor building, and now uses zero altitude air discharge. I live about two miles away from this plant.

As far as using other isotopes for RTG's--this is certainly possible. However, the overriding power generating capacity of a quantity of isotope is more of a function of the half-life than the actual energy spectrum of the emmitted radiation. For Americium-241 with half-life of 400+ years, the amount of decay heat produced will be approximately 87/432 which is near 1/5 of what Pu-238 generates. So an equivalent RTG will require approximately 5 times the isotope fuel loading that a Pu-238 one would need, to get the same power.

stungun · Veteran Member

A rather sly change of subjects, Mr Iprimap. DOE does it all the time to avoid responding to how provably un-containable pu-238 production is. Do you have any scientific reason to neglect the NAS advice for "emission free treatments" to share with us? Well...neither does DOE!

So it is best to change the subject to chlorine. I am surprised you did not mention your favorite deadly 6 inches of water for another incredulous analogy...

You then refocus the arguement by limiting our choices to other nasty battery sources. Pu-238 IS a neutron emitter too, by the way...

The "other" alternatives, not listed, are better than the choices you listed. Solar space exploration, like Deep Space 1, until TRUE energy breakthroughs are made for clean energy. There is NO RUSH to get a man on mars until we can correct the covered up HEPA containment flaws.

And yes, the russians and chinese need to corral their pu-238, and their blind lust for nuclear domination too. There are international efforts underway. While your agruement that SINCE the russians will do it, we must too, holds little logic. If Putin uses pu-238 and their spacecraft pollute the earth's children, it is just as much of a crime against humanity. We don't need pu-238 for spy satelites, period. Lil' Bushmeister is the guy who is breaking so many international treaties etc, and the guy firing up pu-238 production for "undisclosed national security reasons."

But it will take the citizens of all countries to take back their governments. To paraphrase Einstein, "The forces of the military-industrial complex are so self perpetuating, it will take an educated and informed citizenry to ever stop it."

DOE does it's best to avoid spreading problem information, like HEPA leaks and seismic support bolts falling out. That seems like important stuff to me, and now the NAS...

Lord Flasheart · Member

stungun wrote:

So it is best to change the subject to chlorine. I am surprised you did not mention your favorite deadly 6 inches of water for another incredulous analogy...

Ounces, Stunny, ounces.

Stunny, I'd strongly suggest that you throw all your support into fusion power. Obviously the power produced from fusion reactions is much more than that of fission plants, and quite a few fusion fuels are anuetronic. I'm not saying that fission plants will be out of the picture entirely! We'll still need some radioactive material for medicine and the like. But if you're giving your all for fusion power, you're definitely doing both nukes and anti-nukes a favor, all for the better of Earth.

EDIT: Whoops! I caught a mistake. Aneutronic is spelled like so.

-- Edited by Lord Flasheart at 00:43, 2005-10-10

stungun · Veteran Member

Oh Lordy, Lordy, Lordy, y'all found something to correct! Yes, I was transposing a different pro-nuke analogy I have heard. You are correct, Iprimap has refered to the deadly 6 "ounces" of water when comparing the threat of inhaling pu-238. Though sillier and similar, I stand corrected!

But I did have to look up aneutronic fusion, so I learned sumptin' today! I won't put all my eggs in that basket, but yes, it would help us all. Similarly, I learned from Iprimap's fusion etc post the other day. Y'all can be informative...sometimes...

10kBq Jaro · Senior Member

SG wrote:

"Alpha recoil " is a DOE term, for the ability of alpha emitters, like plutonium, to "creep " through 4 HEPA filters in a row! Nobody knows how much plutonium comes out of the last filter.

This is interesting.

I guess I could believe that an alpha particle, with an atomic mass of 4 AMU (2 protons + 2 neutrons) could give a single plutonium nucleus with 238 AMU mass a pretty decent kick. The energy the alpha carries is only a few MeV -- much less than the ~180MeV typical of the spontaneous fission that causes the fission products of natural uranium inside minerals to recoil, creating recoil TRACKS that can actually be visualised by etching the crystal surface with acid and viewing under a microscope (as part of the common technique called fission track dating).

A cluster of two or three plutonium dioxide (PuO2) molecules would hardly notice the bump from an alpha recoil however, and any sort of dust mote, containing many billions of PuO2 molecules would be totally unaffected. Moreover, a cluster that big would have alphas going off on all sides of its surface in fairly rapid succession, thus resulting in zero net thrust -- the particle wouldn't go anywhere, even if the alphas had much more energy than the little bit they actually do.

Alpha recoil is a much more important phenomenon with gaseous substances (i.e. single atoms or molecules, not dust particles) -- where it has been found, as long as 60 years ago, that high vapour pressure (i.e. low melting point) radioactive materials like Polonium-210 can actually create detectable contamination on surfaces upstream of a light air draft.

But remember that once the Pu-238 decays by emitting an alpha, it is no longer Pu-238: it changes to U-234, with a half-life of 247,000 years -- so the next kick isn't coming for quite a while.

Also, the ejection of alphas by dust particles causes them to gain electrostatic charge ( -2 for each alpha emission). This effect is actually used in a variety of applications, including dust suppression in certain high-tech industries, where the source material used may be Americium-241, as in smoke detectors (but a much larger quantity -- a million times greater or more).

So you'll forgive me if I don't buy your story of plutonium dust creeping through HEPA filters -- although I'm sure it makes a great scare story for anyone who's already terrified of all things nuclear, and especially the so-called "deadliest substance on earth," plutonium.

stungun · Veteran Member

Hi Jaro,

Well, please note the DOE McDowell experiment, and the others I quoted, used elemental multi-atom alpha emitting elements, like pu-239, NOT gases, nor 2-3 atom particles.

So, you are confidently making calculations and statements that are provably untrue, and you are baselessly ignoring the NAS advice. The NAS actually read my evidence. It is a new technique, perhaps, for you, but reading the evidence helps avoid making stuff up to convince yourself it is appropriate to avoid the deadly details.

10kBq Jaro · Senior Member

OK, so which part of my statements are "provably untrue" ? ....that an alpha has 4 AMU mass versus 238 for Pu ? ....that the alpha decay induces a double electrostatic charge on the particle ? ...or what ? ....are you suggesting some sort of "new physics" ?

FYI, I'm NOT very impressed by your submission to the NAS. This is a favourite tactic of all sorts of antinuke types -- I guess it makes them feel important. When I read of characters like Rosalie Bertell taking advantage of such public consultation processes to push her antinuke ideology, it just turns my stomach. But I guess it can't be avoided, because its a "free country." Of course once the submittal is logged into the NAS proceedings, then the antis can use that to cite themselves in impressive-sounding references. What balloney !!!

stungun · Veteran Member

Hi Jaro,

You are mistaking the "submission" of comments to the NAS panels, with the fact that my advice is actually "taken" by the NAS and "printed" in the NAS report as the "NAS" learned opinion. I am not falsely bragging that I testified, which of course, is no big deal. But what i said and wrote is provably true, and they now have the same documented opinion as I do. That is worth bragging about, and serves as the proof, to counter your mis-informed dismissal.

You ask, "OK, so which part of my statements are "provably untrue" ? "

This is not "new physics" as you mock. I gave my reference of the DOE McDowell paper using the actual particles that you declare would be "totally uneffected."

Jaro claimed, "A cluster of two or three plutonium dioxide (PuO2) molecules would hardly notice the bump from an alpha recoil however, and any sort of dust mote, containing many billions of PuO2 molecules would be totally unaffected. Moreover, a cluster that big would have alphas going off on all sides of its surface in fairly rapid succession, thus resulting in zero net thrust -- the particle wouldn't go anywhere, even if the alphas had much more energy than the little bit they actually do. "

10kBq Jaro · Senior Member

As someone once said, "extraordinary claims require extraordinary evidence."

You cite one DoE paper, without providing details. This is not very convincing, as there are thousands of papers written under the aegis of DoE. I could probably find one that discusses UFOs.

But I'm glad you took note of my comment, "A cluster of two or three plutonium dioxide (PuO2) molecules would hardly notice the bump from an alpha recoil however, and any sort of dust mote, containing many billions of PuO2 molecules would be totally unaffected. Moreover, a cluster that big would have alphas going off on all sides of its surface in fairly rapid succession, thus resulting in zero net thrust -- the particle wouldn't go anywhere, even if the alphas had much more energy than the little bit they actually do. "

This is just plain mechanics. Suggesting otherwise constitutes an extraordinary claim, which requires extraordinary evidence. You haven't shown it to us.

stungun · Veteran Member

Hi Jaro,

You are sounding as logical as the Red Queen at the MadHatter's Tea Party. I know it is hard to admit you are wrong, but your denial and dismissal is contradicted by the Natl Acad of Sciences. Take a deep breath, then relax your sphincter, and pull your head out of the dark.

Jaro now insists, "You cite one DoE paper, without providing details. This is not very convincing, as there are thousands of papers written under the aegis of DoE. I could probably find one that discusses UFOs."

So your argument ignores the TWO papers I provided, and the NAS endorsement of the details involved. Instead, you oddly claim you can find a DOE paper on UFO's! Again Jaro, maybe you CAN find a DOE paper on UFO's, but let us know when the NAS publishes your paper's conclusion in agreement. You are just so myopic it is getting funny...

Here is a snip from my paper- try reading it!! "The DOE has known of this problem since the 1970's, but has chosen
to ignore it. I have 2 papers from DOE on this. One is from WJ McDowell,
from Oak Ridge. For the 14th ERDA Air Cleaning Conference, he writes a
paper called " Penetration of HEPA filters By Alpha Recoil Aerosols."
He says "Tests at Oak Ridge National Laboratory have confirmed that
alpha-emitting particulate matter does penetrate High-efficiency filter
media, such as that used by HEPA filters...Filter retention efficiencies
drastically lower than the 99.9% quoted for ordinary particulate matter
were observed with Pb-212, Es-253, and Pu-238 sources, indicating that
the phenomenon is common to all of these..."
    It seems as if the alpha particle, from the radioactive decay,
literally knocks the particles loose. As it creeps through any filters
that is in it's way, the DOE thinks that smaller pieces of the
plutonium particles, break off the original particle, increasing the joy
of downwinders.
   Another DOE paper comes from Arthur H Biermann, at Lawrence
Livermore, from Dec,11,1991. His paper is called,"Alpha migration
through Air Filters: A Numerical simulation." He says ," It is obvious
from the review of the literature that evidence exists of the migration
of alpha radionuclide species through high efficiency filter media."
    Both papers have many DOE references, and both call for quantifying
the true releases , in lab experiments.

10kBq Jaro · Senior Member

Incidentally, it may be of interest that this simple collision mechanics also applies in nuclear reactor operation, in the "moderation" of neutrons propagating the fission chain reaction.

The neutrons born during fission typically have an energy from 0.1 to 4 MeV (roughly same order of magnitude as the alphas in Pu-238 decay). To slow them down effectively - which is an absolute must for thermal neutron reactor operation - requires that the fast neutrons collide with other particles of approximately equal mass. That is why water makes such an excellent neutron moderator: the hydrogen proton has nearly identical mass to the neutron. A lot of momentum is transferred during each neutron-proton collision, and within just a few collisions the energy of the neutron is reduced from ~2 MeV to 0.000,000,002 MeV (or 0.002 eV). If your reactor contains no low-mass moderating material, the neutrons just bounce off other uranium fuel or structural metal atoms, like tennis balls bouncing off a concrete wall. They eventually slow down (if they don't get absorbed first), but only after a great many collisions.

Being electrically charged, the alphas of course don't bounce around for nearly as long. In fact, a thin sheet of paper will stop them, whereas neutrons can pass through a foot of concrete. Beta rays, by comparison, being singly-charged (only) electrons, can penetrate quite a bit deeper than alphas.

Anyway the point is that simple mechanics says that a relatively small particle like an alpha will not propell a dust partice containing a great many heavy Pu and O atoms -- especially not when other alphas on the opposite side of the particle are pushing in the other direction. And the fact remains that even tiny dust particles contain a huge number of atoms....

10kBq Jaro · Senior Member

SG wrote:

Here is a snip from my paper-

You are very good at repeating your previous posts. Congratulations. But why the reluctance to actually add some useful technical information ? It may not be obvious to you, but just citing some obscure DoE paper does little to provide convincing evidence. You are evidently unaware of the fact that science does NOT equal accepting hearsay at face value. Not even if its by NAS, or one of its panels, like BEIR 7.

stungun · Veteran Member

Well, Jaro, despite all your mental masturbation denying HEPA filters allow plutonium particles to creep through multiple HEPA filters, you seem to miss the point that it has already been documented!

AGAIN, from Oak Ridge, with NAS agreement...

"Filter retention efficiencies drastically lower than the 99.9% quoted for ordinary particulate matter were observed with Pb-212, Es-253, and Pu-238 sources, indicating that the phenomenon is common to all of these..."

Ordinary particulate matter Jaro! You know how to read, but I again remind you, you must pull your head out first...

iprimap · Veteran Member

Dr. Stungun,

I agree with your intimation that HEPA filtration is not 100% perfect. But if its efficacy in combination with other control mechanisms is sufficient to ensure that release levels are limited to 15 pico-curies or less to the environment (the US EPA limit - see web page http://www.epa.gov/docs/rpdweb00/radionuclides/plutonium.htm), then surely there is no room for complaint.

The real issue with anti-nuclearists has been that no radioactive containment mechanism is 100% perfect. These activists demand 100% perfection, but such an idealized state is neither achievable nor practical (nor does it even exist in nature). To ensure safety in the use of radioactivity, these activists should embrace what NRC Chairman Nils Diaz calls realistic conservativism. Now I'll grant you that Dr. Diaz wasn't referring to Pu-238 specifically when he gave the following speeches, but what he says about how unrealistic safety expectations are themselves UNSAFE applies equally well to the use of Pu-238 for RTGs, HEPA filters, etc. ad nauseam.

Realism and Conservativism: http://www.nrc.gov/reading-rm/doc-collections/commission/speeches/2003/s-03-023.html

Realistic Conservativism: http://www.nrc.gov/reading-rm/doc-collections/commission/speeches/2003/s-03-009.html

Realistic conservativism is not something that anti-nuclearists embrace for they desire not realism - that would shatter their anti-technology myths and species-suicide intent - and they utterly oppose conservativism when it is they who have to conserve. Ah yes, I know that's a twist on words, but a true twist nevertheless.

While he spoke mainly to the commercial nuclear power crowd, Dr. Diaz's approach of realistic conservativism nonetheless applies equally to commercial nuclear power plants, Pu-238 fueled RTGs, nuclear-propelled submarines and aircraft carriers, and NERVA spacecraft. The US DOE certainly doesn't garner any loyalty from me (big government can never do better what free enterprise can do on its own), but they'll have my support before4 any anti-nuclearist.

I will remind Dr. Stungun of the truth one more time: much to his derision, I have repeatedly cited how even water is not 100% safe. Yet in spite of the fact more people have died from the effects of water than Pu-238, most human beings can safely use water. Few of us have aqua-phobia. Why then the Pu-phobia? Or how about auto-phobia - automobiles kill thousands each year? The list is endless and I suspect that the concern isn't for safety, but rather for public acclaim.

Regards,

Paul

stungun · Veteran Member

Hi Paul,

RE: If HEPA pu-238 releases meet EPA standards "then surely there is no room for complaint."

1) Because the true release of the total pu-238 that whispers through multiple HEPA filters is provably UNKNOWN, it is NOT possible yet, to claim that the EPA limit is not exceeded. Dr. Liu's "total capture" technique could be used to accurately assess it, but DOE has refused.

RE: "These activists demand 100% perfection, but such an idealized state is neither achievable nor practical (nor does it even exist in nature). "

2) It is the NAS that backed my HEPA complaints with a call for "emission free treatments." The NAS obviously disagrees with you that it is unrealistic or not needed.

That makes two, you and Jaro, on this "science" board who dismiss the NAS advice, as their main argument. Claiming the Nat'l Acad of Sciences is an eco-commie plot is hardly a science discussion.

Your main problem is not understanding that, despite HP numbers, inhaling pu-238 is not the same as eating a banana with unavoidable naturally radioactive potassium. Inhaling pu-238 is not the same as getting more scattered background radiation from moving to the mountains. And, ummm, it ain't the same as the threat of 6 inches of deadly water.

You are demonstrating why the DOE has lost debates to me in front of their own scientists. The arguments get laughable and embarrassing, even for nuclear scientists...

10kBq Jaro · Senior Member

SG wrote:

AGAIN, from Oak Ridge, with NAS agreement... "Filter retention efficiencies drastically lower than the 99.9% quoted for ordinary particulate matter....

OK, how can I spell it out for you ? Can you provide SPECIFICS about the filter, its installation ? Was it flawed ? ...did it have gaps around the edges ? how big or how small ? ...has the installation been verified somehow ? ...has atest been performed to verify that the same poor results didn't result with non-radioactive materials, as well as with radioactive ones ? ....how was the test performed and validated ? ....how do they test for non-radiactive particle retention ? ....can they guarantee that their detection method didn't miss a whole lot of non-radioactive dust passing through a faulty filter installation, and then assumed that it worked fine for those but not for radioactive particles ? (Hint: these are valid technical questions)

SG, how would you like me to keep demanding that you answer all the above questions, as you yourself are so fond of doing to others ???

PS. no need to re-copy your own quotes for the umpteenth time -- we already know how you love to see yourself in print.

stungun · Veteran Member

Hey Jaro,

Yes, you have shown your ability to ask questions. I gave you the references. NAS read and accepted them. You have not read them, but have proudly listed a couple kindergarden questions, claiming that proves the NAS is wrong. MMMKAY!

I'll provide another quote from my paper you appear to have never read. DOE's Bierman calls alpha recoil problems "obvious", but, I am sure you will be able to ask a rhetorical question to claim that proves him a eco-commie who just likes to see his name in print...

"Another DOE paper comes from Arthur H Biermann, at Lawrence
Livermore, from Dec,11,1991. His paper is called,"Alpha migration
through Air Filters: A Numerical simulation." He says ," It is obvious from the review of the literature that evidence exists of the migration of alpha radionuclide species through high efficiency filter media."

10kBq Jaro · Senior Member

FYI, I am currently involved in a project for repackaging and storing old research reactor fuel. The new storage cans will have very fine filters in their lids. We do not take the manufacturer's word for any claims of performance. In fact we have to prove to the nuclear regulator that the things will work as advertised. Hence we are building a test rig, at considerable expense (including design, instrumentation, manufacturing, and then the testing itself) with which we will verify the performance of the filters, as well as the closure around them.

You may think I'm asking "kindergarden questions," but I assure you any self-respecting regulator would ask the same questions. Trust me, this is not about hand waving -- common though it may be in YOUR profession.

stungun · Veteran Member

RE: Kindergarden questions

Jaro, the specific questions you asked about the McDowell and Beirman papers are basic, and are OK, but hardly "evidence" to argue against the NAS advice.

For example."Was it flawed ? ...did it have gaps around the edges ? " Ummm, NO!

Jaro's deep question in context, as he wrote them...

"Can you provide SPECIFICS about the filter, its installation ? Was it flawed ? ...did it have gaps around the edges ? how big or how small ? ...has the installation been verified somehow ?" Read the references Einstein... NAS DID! How can you breath with your head so far up there?

10kBq Jaro · Senior Member

Apologies for being such a slow reader.

But I'm certainly glad to have taken the time to do the reading, as its quite informative.

As we all suspected, emissions monitoring of the HEPA filters at existing facilities has shown them to be very effective :

Purification, Pelletization, and Encapsulation—Normal operation releases from purification, pelletization, and encapsulation were based on stack monitoring data from the operations at LANL's Plutonium Facility at TA-55. Plutonium-238 emissions from the LANL Plutonium Facility between 1997 and 2003 ranged between 4.7 × 10-9 to 8.63 × 10-9 curies per year. These emissions from TA-55 of the facility containing the plutonium-238 operations are exhausted through Stack AES-15," which is filtered by four stages of highefficiency particulate air (HEPA) filters, with a control efficiency of 99.95 percent for each stage (LANL 2005a).

....process details at the new INL facility are essentially the same as those at TA-55.

Reference is made to the following web site:

http://www.airquality.lanl.gov/Neshap.htm

Historical Stack Emission Measurements

Laboratory stack emissions measurements, some starting as early as 1994 for some species, are now available. We will continue to add historical data to this collection as time and resources permit.

http://www.airquality.lanl.gov/Stacks/AnnualSourceTerm/AnnualSourceTermAll.htm

Example, for the year 1997:

http://www.airquality.lanl.gov/Stacks/AnnualSourceTerm/1997Data/AnnualSourceTerm55000415.html

1997 Annual Emissions Summary for Radioactive Air Emissions for Sampled Stacks

07/11/2001 TA-55-004 FE-15 RRES-MAQ ESIDNUM: 55000415

Nuclide Emission (Ci)

Am-241 3.99E-08

Pu-238 8.13E-09

Pu-239 6.04E-08

Th-228 4.45E-08

U-238 2.82E-08

_______________________________________

Worker doses due to plutonium-238 purification, pelletization, and encapsulation activities at LANL’s Plutonium Facility at TA-55 were obtained from 12 years (1993 to 2004) exposure data for workers involved in plutonium-238 operations (LANL 2005b). These doses are total measured internal and external radiation dose based on actual worker dosimetry data and by periodic worker biosafety monitoring. This data showed that an average of 79 workers have received 0.243 rem each annually for a collective dose of 19 person-rem per year.

3 During peak plutonium-238 production years, a few workers at the LANL TA-55 Plutonium Facility received total annual doses of up to 2 rem each, which was the worker maximum dose administrative limit.

The new facility at INL, currently in the conceptual design phase, will meet or exceed all safety design features of the REDC and LANL Plutonium Facility. This includes four separate dry HEPA filters for all air exhausted through the stack.

Once again, thanks for suggesting that I do a bit of reading !

-- Edited by 10kBq Jaro at 04:45, 2005-10-12

stungun · Veteran Member

Hi Jaro,

Yes, those are the DOE figures, admitting some leakage, although very little.

The NAS was aware of tiny claims of DOE HEPA figures when they advised for "emission free treatments." I paste a URL for Dr Steve Wing's report on LANL, that differs a little from the DOE version. You will see the unexplained presence at LANL of pu-238 four to twenty times the estimates from DOE. And higher than backgound levels of pu in autopsies of citizens who never worked at LANL. Despite all the DOE figures, this pu creept out of the buildings and into the bodies of local citizens.

What is not discussed is the actual monitoring of alpha emitters is very subjected to the grab samples, and the particle sizes tested for. This is why I call for Dr Liu's "total capture" technique. The DOE can not presently determine the total amount of pu-238 that whispers out of 4 HEPA filters. How did the pu show up outside the building higher than DOE estimates?

http://www.nuclearactive.org/docs/RTKExecSumm.pdf

Your quote on worker's doses is contradicted by the actual March 16, 2000 LANL accident report (Type A accident).

You say...

"During peak plutonium-238 production years, a few workers at the LANL TA-55 Plutonium Facility received total annual doses of up to 2 rem each, which was the worker maximum dose administrative limit."

However, just this one, of several recent accidents, according to the actual accident report, estimated that at least 3 workers exceeded their annual 5 rem dose, and another had a lifetime effected dose of 300 rem. These guys were all put on immediate EDTA chelation therapy too, so their dose would be higher in the old days before EDTA. I only have this report in pdf, but I will try to send that to your website. I was citing page 4. I got it from DOE, but I have not found it on the web...

GoogleNaut · Guru

With all the interest in alpha emitters, I've become interested by the phenomena of "Alpha Recoil Transport" and have been doing some calculations. I was going to post it here, but I think that with five pages or so, it might more appropriate if I did a write up, something like an "Isotope Calculations Primer" which is where I'm headed. If it would be informative, useful, and enlightening I think I will continue to work on it.

Ty Moore
"GoogleNaut"

10kBq Jaro · Senior Member

I think its important to take into account the specific material being used, and its physical properties -- most importantly its vapour pressure, because this may in some cases volatilise a (radiologically) significant amount of the material above the solid phase, which then plates out on the room walls and in the HEPA filters.

For a long-lived radioisotpe, the parameter of concern in this respect is simply the melting point: the closer it is to the room (lab) temperature, the higher the vapour pressure. A familiar example of this type is Polonium-210.

But for relatively shorter-lived radioisotopes, the nuclear decay self-heating of even small pellets can raise their temperature by several hundred degrees (red-hot in the case of Pu-238), which is obviously well above the ambient temperature, hence closer to the materials' melting point, with increased vapour pressure.....

stungun · Veteran Member

Hi Jaro,

While these are good issues to consider, it seems the melting point of pu isotopes is well over 1,000 degrees F. I think even with incineration, the effluent is of a temperature that all pu in the HEPA filter system is in the particulate form...

10kBq Jaro · Senior Member

SG wrote:

While these are good issues to consider, it seems the melting point of pu isotopes is well over 1,000 degrees F. I think even with incineration, the effluent is of a temperature that all pu in the HEPA filter system is in the particulate form...

Claiming that "the effluent is of a temperature that all Pu in the HEPA filter is in particulate form" is definitely wrong. Even cold steel has a certain - admittedly extremely low - vapour pressure, with a small number of iron atoms floating above its exposed surface. The question is only how much, and which effect is dominant, under the various conditions.

Similarily, that the McDowell paper apparently only considers alpha recoil as the exclusive cause of his experimental results is, in my opinion, highly unscientific. Particularly with Pu-238, which self-heats to a high temperature. As I already wrote earlier, I have a hard time believing that alpha recoils can push around million-atom clusters. Single atom alpha recoil in the vapour phase is a far less improbable phenomenon.

McDowell apparently claims to have found such million-atom cluster particles in his HEPA filter. But its one thing to measure radioactivity and see particles, and quite another to conclude that the particles you see under a microscope are in fact the source of that radiation. Its just as easily possible that the radiation is coming from vapour plate-out in the filter, while the microscopic particles are simply some incidental non-radioactive junk. Its not a trivial thing to prove it one way or the other (i.e. you cannot simply put a Geiger counter up to a submicroscopic particle and measure its radioactivity...).

It seems to me that there may actually be an opportunity for performing a truly scientific analysis here, considering all the possibilities and their relative magnitudes in an unbiased way, and publishing a paper in a peer-reviewed journal such as Health Physics or Nuclear Science & Engineering - along the lines of Ty's suggested writeup....

I would caution however, that the above discussion probably has little relevance to the practical use of HEPA filters, as the required monitoring in the downstream exhaust stack ensures that any deterioration in performance -- regardless of the cause -- is simply corrected by changing the filters. Even McDowell says that "regular testing missed the alpha creep because of the short duration of their testing," because he "left his test up for one year." Obviously, if you keep changing your filters on, say, a quarterly basis, then you will never see the HEPA filter deterioarition found by McDowell, regardless of the cause. But it would certainly make for an interesting, purely scientific investigation.