Air Sampling Problem in an Alpha Facility

[SmearedNeutron]

The facility I work at has recently experienced an air sampling event that we are having difficulty agreeing upon how to handle. A grab sample was taken on a filter and counted in a SAC-4. Initial indication was that the area should be posted ARA per our procedure. (Radon can always be a factor, as you well know, so the sample was held for a decay count.) Upon decay count, the sample was well below ARA limits. However, the technician counting the sample felt that the rate of decay was TOO great to be attributed to radon, so a 2360 with a 43-93 was used to investigate the sample envelope. Upon placing the probe in the envelope, activity was detected. A smear was then taken of the interior of the envelope and activity was also detected on the smear. The smear was held for decay counts, but has failed to decay after weeks of counting.

Have you ever had your activity jump from the sample filter to the sample envelope?

Is this still an air sample, or is it a now a smear?

How would you handle this?

[Marlin]

However, the technician counting the sample felt that the rate of decay was TOO great to be attributed to radon,

Based on what experience at your facility or the range of decay rates for Radon/Thoron?

Upon placing the probe in the envelope, activity was detected. A smear was then taken of the interior of the envelope and activity was also detected on the smear. The smear was held for decay counts, but has failed to decay after weeks of counting.

Have you monitored clean envelopes for possible contamination.

Do you have, or have access to alpha spectroscopy... silly question there are lots of labs you can send it to.

Have you ever had your activity jump from the sample filter to the sample envelope?

Minimal unless you have overloaded your sample media.

Is this still an air sample, or is it a now a smear?

Radioactive material, a sample implies a small part of a whole that is representative of the whole.

How would you handle this?

Nukeworker is a good start I am sure you will get a couple of more responses.

[tolstoy]

The facility I work at has recently experienced an air sampling event that we are having difficulty agreeing upon how to handle. A grab sample was taken on a filter and counted in a SAC-4. Initial indication was that the area should be posted ARA per our procedure. (Radon can always be a factor, as you well know, so the sample was held for a decay count.) Upon decay count, the sample was well below ARA limits. However, the technician counting the sample felt that the rate of decay was TOO great to be attributed to radon, so a 2360 with a 43-93 was used to investigate the sample envelope. Upon placing the probe in the envelope, activity was detected. A smear was then taken of the interior of the envelope and activity was also detected on the smear. The smear was held for decay counts, but has failed to decay after weeks of counting.

Have you ever had your activity jump from the sample filter to the sample envelope?

Is this still an air sample, or is it a now a smear?

How would you handle this?

Was back-up air sampling performed? How close was the actual decayed activity to a calculated decay?

If air activity isn't conclusive I would focus in Marlin's question about the envelopes...

[Jason9x]

What isotopes are you working with?

[SmearedNeutron]

What isotopes are you working with?

Pu-239 & Am-241

Was back-up air sampling performed?

There was an alpha CAM running just a few feet away that did not alarm, though the CAM had a higher DAC setting than the air sample calculated out to be. There were no lapels running, as the RWP did not require them for the work being performed in that area.

How close was the actual decayed activity to a calculated decay?

There has been really no perceivable decay following the first 24 hours, which was minimal. Successive counts have fluctuated up and down a few dpm.

Based on what experience at your facility or the range of decay rates for Radon/Thoron?

The technician counting the sample has 20+ years experience and more than 5 in this facility.... primarily counting air samples. Historically, we have been able to see appreciable decay within 1-2 hours (complete radon decay within 24), but not a complete loss of activity, as was the case here.

Have you monitored clean envelopes for possible contamination.

Do you have, or have access to alpha spectroscopy... silly question there are lots of labs you can send it to.

No, not in the past. However, the sample envelopes in question are surveyed to <20/<100 prior to removal from CA into RBA for counting. (The envelopes also start out in a clean area and are taken to the job location and normally kept uncontaminated for the duration of the job by placing them out of the way)

It just so happened that the on-site alpha spec went down that day and has yet to be fully analyzed.

Minimal unless you have overloaded your sample media.

Sample loading was by no means extreme, short run time and only about 500dpm total activity.

Hope the added information helps.

Thank you for the responses, I hope to see more.

[SloGlo]

inn my limited experience, aye have scene little cross contamination from a/s media two envelope container  
 that sayed, eye have had r.a.m. from sample media transfer too container surfaces, most often with highly energetic isotopes and containers witch easily obtain a charge, like a polystyrene.  
   sew, watt is yore enevelope's construct?

it wood a peer that yew now have an a/s sample and a sample of easily removed r.a.m. from the transference container.

eye would handle it with tweezers.

[Marlin]

Pu-239 & Am-241

Raffinate lines with other isotopes?

There was an alpha CAM running just a few feet away that did not alarm, though the CAM had a higher DAC setting than the air sample calculated out to be. There were no lapels running, as the RWP did not require them for the work being performed in that area.

Is the CAM a fixed filter CAM that can be analyzed?

There has been really no perceivable decay following the first 24 hours, which was minimal. Successive counts have fluctuated up and down a few dpm.

That would leave out thoron with an ~10 hour half life.

The technician counting the sample has 20+ years experience and more than 5 in this facility.... primarily counting air samples. Historically, we have been able to see appreciable decay within 1-2 hours (complete radon decay within 24), but not a complete loss of activity, as was the case here.

I hate to ask with a tech having that much experience but is there a possibility of cross contamination.

No, not in the past. However, the sample envelopes in question are surveyed to <20/<100 prior to removal from CA into RBA for counting. (The envelopes also start out in a clean area and are taken to the job location and normally kept uncontaminated for the duration of the job by placing them out of the way)

In line with the cross contamination question was he the only one in the area?

It just so happened that the on-site alpha spec went down that day and has yet to be fully analyzed.

Murphy's Law  

Sample loading was by no means extreme, short run time and only about 500dpm total activity.

Millipore filters? With such a low activity it seems unlikely that there would be a significant transfer of activity to the envelope unless like SloGlo said you have an envelope with a static charge.

Probably problem solved when you get your spectroscopy unit back up.  

[SloGlo]

The technician counting the sample has 20+ years experience and more than 5 in this facility.... primarily counting air samples. Historically, we have been able to see appreciable decay within 1-2 hours (complete radon decay within 24), but not a complete loss of activity, as was the case here.

sew, the a/s filter lost all of it's  activity in 24 ours.
their was activity in the envelope after this time frame had past.
the activity in the envelope has knot decayed a dpm in the time since.

due aye have this correct?

[GLW]

you type envelope and we all get a certain picture in our heads,...

what is your envelope, and where are you procuring them from,...

radioactive cross contamination is rife, the world over,...

Occam's Razor,...

rule out or indict the envelopes,...

then come back with more,...

[SmearedNeutron]

you type envelope and we all get a certain picture in our heads,...

what is your envelope, and where are you procuring them from,...

I'll have to get back to you on the source, but the envelopes are of a heavy "card stock" variety, somewhat orangish-yellow in color with a square shape.

sew, the a/s filter lost all of it's  activity in 24 ours.
their was activity in the envelope after this time frame had past.
the activity in the envelope has knot decayed a dpm in the time since.

due aye have this correct?

Sorta. The a/s filter was counted again 2 hours later and "lost all its activity". There was activity in the envelope after this time period and that activity was smearable. That smeared activity has not decayed since.

eye would handle it with tweezers.

We do. Always.

[SmearedNeutron]

Raffinate lines with other isotopes?

Pretty pure at this point. Buttons were produced here.

Is the CAM a fixed filter CAM that can be analyzed?

Yes.

I hate to ask with a tech having that much experience but is there a possibility of cross contamination.

Tech A taking sample is not Tech B counting sample. Tech taking sample has considerably less experience than Tech counting sample. Cross contamination is a possibility (and leading theory amongst people of a higher pay grade than I), but I believe the sampling tech to be competent to prevent CC, just as I have faith in the counting tech and their experience with these issues. (I should say now, I am not Tech A or B... I am Tech Z, just trying to assemble the puzzle as well.)

In line with the cross contamination question was he the only one in the area?

Murphy's Law   

No.

Yes.

Millipore filters? With such a low activity it seems unlikely that there would be a significant transfer of activity to the envelope unless like SloGlo said you have an envelope with a static charge.]

Versapore, actually.

--------------

Bottom line, I'm on the fence. Could be cross-contam,  could be a real ARA. I'm just looking to broaden the idea input base at the best place I know.

[GLW]

Tech A taking sample is not Tech B counting sample. Tech taking sample has considerably less experience than Tech counting sample. Cross contamination is a possibility (and leading theory amongst people of a higher pay grade than I), but I believe the sampling tech to be competent to prevent CC, just as I have faith in the counting tech and their experience with these issues. (I should say now, I am not Tech A or B... I am Tech Z, just trying to assemble the puzzle as well.)

it does look like tech A is the "source",....

problem is how?

where did Tech A acquire the envelope?

why would a ready for issue envelope have contamination inside it?

it's not that easy to dam near impossible to inadvertantly cross contaminate the interior of an envelope through standard handling methods,...

you have to intentionally load something into the envelope,...

so, my 10,000 foot view is:

Tech A grabbed an envelope from somewhere other than normal protocol for reasons known only to Tech A,...

turns out that was a FUBAR move,...

and now Tech A refuses to budge on the envelope origin backstory for reasons known only to Tech A,...

everybody has done something that seemed easy enough but, because of the implaccable, unforgiving nature of radionuclides, it turns out that the most inane of reasons for doing things "just so" is buried in thousands of man-years of operating experience and was learned the hard way long ago,...

it is also why we throw away so much stuff that looks clean and pristine but is not proven clean and pristine; the man hours to prove it are far more expensive than trashing the suspect product and buying new product, even with a SAM only two buildings away,...

it would be so much easier for everybody to document this as a HU area for improvement and move on,...

without that, this becomes a monotonous "chase down all the possibilities and rule them out" paper chase,...

and it's holiday season,...

then again,...the world is rife with cross contamination in new product issues nowadays,...

[Marlin]

Bottom line, I'm on the fence. Could be cross-contam,  could be a real ARA. I'm just looking to broaden the idea input base at the best place I know.

  Transuranics can be highly mobile in loose contamintion, I would bet on cross contamination. Does not sound like a big problem if there is no significant assigned DAC hours only a poser for future consideration.

[GLW]

  Transuranics can be highly mobile in loose contamintion, I would bet on cross contamination. Does not sound like a big problem if there is no significant assigned DAC hours only a poser for future consideration.

eeeyup, and facilities with TU have standard methods and protocols to circumvent that high mobility,...

and sometimes those methods and protocols are carrying the force of procedural compliance,...

which can change the dichotomy from boot to the head and don't do another bonehead, to X days off, letters in the file, blah, blah, blah,...

it's a sadder world sometimes and anymore,...

[SloGlo]

Sorta. The a/s filter was counted again 2 hours later and "lost all its activity". There was activity in the envelope after this time period and that activity was smearable. That smeared activity has not decayed since.

.when the envelope interior was smeared, was any r.a.m. remaining on the envelope interior walls?

[SmearedNeutron]

.when the envelope interior was smeared, was any r.a.m. remaining on the envelope interior walls?

Yes, there was still about 100 dpm in the envelope.

[SmearedNeutron]

eeeyup, and facilities with TU have standard methods and protocols to circumvent that high mobility,...

and sometimes those methods and protocols are carrying the force of procedural compliance,...

which can change the dichotomy from boot to the head and don't do another bonehead, to X days off, letters in the file, blah, blah, blah,...

it's a sadder world sometimes and anymore,...

What if, just "what if".... individuals on this same job, in the same non-ARA, had positive fecal samples in the previous weeks or months from working off-air?

[SloGlo]

sew, when yew say

Sample loading was by no means extreme, short run time and only about 500dpm total activity.

the reference is to the initial a/s count, the smear count, the post 24 our decay count.... ?

[SmearedNeutron]

sew, when yew say

Sample loading was by no means extreme, short run time and only about 500dpm total activity.

the reference is to the initial a/s count, the smear count, the post 24 our decay count.... ?

SloGlo, I'm just gunna sai eet. Ewe can spell nicer. Eye've saw eet. Ewe ain't no eediot, so please stop typing like one.

That said, the initial count was about 5 DAC, whereas the count 2 hours later was less than 0.01. That is what piqued the counting techs interest.

The problem comes in where the tech finds the activity in the envelope and is able to smear it.

The smear does not decay.

Is it a smear or an air sample now?

[GLW]

What if, just "what if".... individuals on this same job, in the same non-ARA, had positive fecal samples in the previous weeks or months from working off-air?

....it would be so much easier for everybody to document this as a HU area for improvement and move on,...

without that, this becomes a monotonous "chase down all the possibilities and rule them out" paper chase,...

and it's holiday season,...

then again,...the world is rife with cross contamination in new product issues nowadays,...

Tech A is unknowingly bringing stuff in from off-site?!?!?!?

some clothing or stores locker somewhere on-site is contaminated when it should not be?!?!?!?

"what ifs" can suck, they can also be the answer,...

they really suck during holiday season,....

[SloGlo]

SloGlo, I'm just gunna sai eet. Ewe can spell nicer. Eye've saw eet. Ewe ain't no eediot, so please stop typing like one.

That said, the initial count was about 5 DAC, whereas the count 2 hours later was less than 0.01. That is what piqued the counting techs interest.

The problem comes in where the tech finds the activity in the envelope and is able to smear it.

The smear does not decay.

Is it a smear or an air sample now?

aisle worry about spelling and sin tax when internet hooligans quit beating on udders about it.


yins got too media fore counting purposes,  (1) clean a/s (2) a smear with unreported activity level.
ya all sew got r.a.m. in an envelope to dispose as procedure dictates.

[SmearedNeutron]

aisle worry about spelling and sin tax when internet hooligans quit beating on udders about it.


yins got too media fore counting purposes,  (1) clean a/s (2) a smear with unreported activity level.
ya all sew got r.a.m. in an envelope to dispose as procedure dictates.

Yes.

[SmearedNeutron]

Tech A is unknowingly bringing stuff in from off-site?!?!?!?

some clothing or stores locker somewhere on-site is contaminated when it should not be?!?!?!?

"what ifs" can suck, they can also be the answer,...

they really suck during holiday season,....

Lines 1 &2 I doubt.

3 & 4 I agree with wholeheartedly.

[SloGlo]

Yes.

weird that unreported activity is a caws four concern.

[SmearedNeutron]

It was reported.

And ignored.

That is the cause of my concern.

[SloGlo]

aye meant unreported hear this hear thread.

with cloudy provided data, isle say yew have two streams of material in that group.

has any buddy cross hatched the smear oar the envelope interior two determine size of activity?

[Marlin]

It was reported.

And ignored.

That is the cause of my concern.

Do you believe there is a continued risk?

Do you believe that there has been an unmonitored exposure or release of material?

Do you believe there may be a potential for over exposure?

  If no to to these questions this is an anomaly that you should be aware of but not grow an ulcer over. Cross contamination does seem to be the most likely answer, put it on your spectroscopy unit when it's back on line, take a back up sample, check applicable bio assays, and analyze the CAM filter. I am probably giving you advice you have already done. You mentioned fecal samples so I assume you are dealing with insolubles.

[SmearedNeutron]

It's okay.

Air monitoring has been discontinued in this area.

All is fine.

[OldHP]

Sounds like it might have been a heavily concreted (or stoned) area, since you never described the facility.  At my last, hopefully not my last, I could pull AS sounding like doomsday on first counting.  They went to watch in 12, to nothing in 24, and bkg in 36!  We ran the final, record, count at 48!

Other sites with environmental AS we ran the last count at 14 days!