Enviro Monitoring vs. Personnel Monitoring

[number41]

Question:  Anybody here work at a site (DOE or Commercial) that has personnel leave their TLD's in a common badge rack on site vs. taking them home?

If your site has employees leave their TLD's at work, why do they do that?  I'm considering that if a plant can build a shielded badge rack for personnel TLD's, then personnel exposure can be dropped by leaving the TLD in the rack at the end of the day.  Our quarterly background runs around 10-15 mRem for the environmental TLD's. By leaving the TLD's in the shielded cabinet, we can cut the exposure personnel currently receive at home, but that is recorded as program exposure..  My rough calculations seem to show that my site could save 8-10 Rem/yr exposure collectively if we were successful.

Any thoughts about the legality and feasibility of this? 

[alphadude]

well.. isnt the purpose to monitor site dose...the risk of loss is so much higher when you take them home.

[number41]

Well, you'd think so..................but I just started here and it seems ridiculous to me that we miss our Exposure goals every year (or so I hear) when a relatively cheap solution would be to do what I have suggested.

[kp88]

Well, you'd think so..................but I just started here and it seems ridiculous to me that we miss our Exposure goals every year (or so I hear) when a relatively cheap solution would be to do what I have suggested.

If you shield your personnel dosimeters, you have to shield your background dosimeters also.  You don't really gain anything here.

[JsonD13]

What the good ol Nav did at p-type was subtract the enviro TLD reading from every personnel dosimeter (they were left on site).  This supposedly allowed for only NNPP dose.  The trick would be that your enviro TLD used for subtraction would have to not be affected by your site, which could be accomplished by having a TLD placed near the fenced area and one placed at the property line (provided there is some good distance between the two).  Then a simple statistical comparison between the two (have to be able to statistically say that both of those TLDs are not affected by your source term) at each read would be sufficient enough to prove that a person is getting that dose from natural circumstances and not the plant. 

I don't know your plant, but if you guys are overshooting your goals, and it hasnt been explained away like this, I'm betting that you are more than just 8-10 man-rem over.

Jason

[RDTroja]

As kp88 noted, each location where dosimeters are stored on site has to have a 'control' TLD for subtracting out background, so it doesn't matter where you store them when they are not in the possession of the owner. Your RCA has to be configured with a minimum (below regulatory concern) dose rate at the borders, so anywhere outside the RCA is fair game (even higher dose areas would work as long as you subtract out the control dosimeter.) Taking the dosimeters home means the potential for loss and unintentional ("I wasn't supposed to wear my TLD for my cancer treatment?") or even malicious ("I wonder how much dose I can rack up sending this thing through the airport x-ray machine") non-occupational exposure that the plant now has to take credit for. Also, taking it home without a control badge guarantees you get to take credit for the non-occupational background unless you can verify that the background levels at each person's house are the same as at the plant. Radon, anyone?

I have seen it done both ways. Personally, I like leaving it at the plant because I can't leave it at home with my badge and keys that way. And no one has to bug me about bringing it in for change out (I don't go into the RCA that much anymore.)

[Khak-Hater]

I haven't worked anywhere in the last ten years that required you to turn in your TLD at the end of the day.  I think PGDP was the last place, and turning in you TLD was part of turning in your Security Badge.  They quit the practice [of turning in either] while I was still there. 

Background TLDs aren't perfect (i.e., the practice of subtracting a Background TLD from each personal TLD exposure reading), since the true background dose for each personal TLD is going to change as that person moves around the plant [or world outside the plant], but it is a commonly accepted practice that is "close enough" and accepted by both the NRC and DOE regulators.  I've run HP Programs under a variety of regulatory jurisdictions and never had any question of that methodology (i.e., the background subtract) by a regulator.

Now lets get to the real problem of this post, which is trying to make an ALARA program look better [on paper] by being clever with your dosimetry administration.  This is the problem of setting cumulative ALARA goals in "Person-Rem" when your overall exposure is down in the weeds.  This kind of bean counting is a discredit to both Health Physics and our industry as a whole.  ALARA is about taking any reasonable precautions to prevent an actual person from getting an actual occupational exposure that is unnecessary.  Whether you record that an individual worker or group of workers has gotten an extra 30 to 60 mrem per year from background radiation (i.e., even if you didn't background subtract) should be inconsequential.  If we really believed that these levels of exposure were a concern, we'd try to teach people to live a more ALARA lifestyle at home.

Sermon over,

MGM

[spentfuel]

Question:  Anybody here work at a site (DOE or Commercial) that has personnel leave their TLD's in a common badge rack on site vs. taking them home?

YES

If your site has employees leave their TLD's at work, why do they do that? 

Because of concern about dose from medical procedures Rad shipments etc, and forgeting to bring it in or loosing it at home or somewhere else

I'm considering that if a plant can build a shielded badge rack for personnel TLD's, then personnel exposure can be dropped by leaving the TLD in the rack at the end of the day. 

As mentioned no need for shielding, control TLD's are used here to subtract the background dose when the TLD is in storgage not when its in use

Our quarterly background runs around 10-15 mRem for the environmental TLD's. By leaving the TLD's in the shielded cabinet, we can cut the exposure personnel currently receive at home, but that is recorded as program exposure..  My rough calculations seem to show that my site could save 8-10 Rem/yr exposure collectively if we were successful.

Again useing control TLD's appropriatly negates the need for shielding.  You will cut collective dose by storing them onsite instead of peeps taking them home.

Any thoughts about the legality and feasibility of this? 

See my comments in bold Most utilitys require TLD'S to be left at site.  May also be part of dosimetry prossesors requirements perhaps associated with NVLAP.

Hope that helps

sf

[number41]

Now lets get to the real problem of this post, which is trying to make an ALARA program look better [on paper] by being clever with your dosimetry administration.  This is the problem of setting cumulative ALARA goals in "Person-Rem" when your overall exposure is down in the weeds.  This kind of bean counting is a discredit to both Health Physics and our industry as a whole.  ALARA is about taking any reasonable precautions to prevent an actual person from getting an actual occupational exposure that is unnecessary.  Whether you record that an individual worker or group of workers has gotten an extra 30 to 60 mrem per year from background radiation (i.e., even if you didn't background subtract) should be inconsequential.  If we really believed that these levels of exposure were a concern, we'd try to teach people to live a more ALARA lifestyle at home.

Well, I can't say that I agree with very much you said.  Maybe it's because there's no room for subtleties on a chat board, but your "holier than thou" attitude automatically turns me off.   What I'm saying is that our site collectively records nearly 25 person-REM per year in background exposure that people pick-up at their homes.  That is nearly 10 percent of our yearly goal blown by people sitting on their couch drinking beer.  You can play the "professional HP" card all you want, but I don't know any business that would knowingly allow their employees to waste 10% of any company asset.  I will agree that ALARA is something that needs to be internalized by the site, but as far as I'm concerned, if you aren't willing to realize that nearly 30% of the American population dies of cancer and you need to do everything within reason to reduce your dose, then have fun explaining that to your family when you're dying of cancer.

Now, back to the question at hand.  If I understand correctly:
1.  The dose collected on our Enviro TLD's can be subtracted from the dose collected by personnel TLD's stored on site.
2.  Some sites (including prototype) store personnel TLD's in badge racks

Sounds like we could store our TLD's at work in a shielded rack and not subtract background.  Or we could store the TLD's in a non shielded rack and subtract background.  Either way, the recorded exposure for each person would be quite a bit lower than if they take their TLD's home.  Does this sound right to anybody or am I totally misunderstanding the way background is corrected?  Thanks for the help guys.

[kp88]

Now, back to the question at hand.  If I understand correctly:
1.  The dose collected on our Enviro TLD's can be subtracted from the dose collected by personnel TLD's stored on site.
2.  Some sites (including prototype) store personnel TLD's in badge racks

Yes, you've got to subtract out some sort of background/control dose.  Plus, a TLD is going to read something immediately after it's annealed.  There's no way to zero one out.  Don't even assign a dose if the TLD reads less than five mrem or so.

[UncaBuffalo]

Sounds like we could store our TLD's at work in a shielded rack and not subtract background.  Or we could store the TLD's in a non shielded rack and subtract background.  Either way, the recorded exposure for each person would be quite a bit lower than if they take their TLD's home.   Does this sound right to anybody or am I totally misunderstanding the way background is corrected?  Thanks for the help guys.

I don't think that follows...if the plant is letting you take the TLD to the house, they have proven to their own satisfaction that the background is the same at plant & house. 

As kp88 noted, each location where dosimeters are stored on site has to have a 'control' TLD for subtracting out background, so it doesn't matter where you store them when they are not in the possession of the owner. Your RCA has to be configured with a minimum (below regulatory concern) dose rate at the borders, so anywhere outside the RCA is fair game (even higher dose areas would work as long as you subtract out the control dosimeter.) Taking the dosimeters home means the potential for loss and unintentional ("I wasn't supposed to wear my TLD for my cancer treatment?") or even malicious ("I wonder how much dose I can rack up sending this thing through the airport x-ray machine") non-occupational exposure that the plant now has to take credit for. Also, taking it home without a control badge guarantees you get to take credit for the non-occupational background unless you can verify that the background levels at each person's house are the same as at the plant. Radon, anyone?

As RDTroja notes, there are variations (Radon, etc) in background...but a plant that sends the TLD home with the worker has decided it's statistically insignificant.

(I've also seen instances where TLDs came back to the plant lower than if they had stayed on site...think closed-automobile in the desert sun...)

[RDTroja]

Now, back to the question at hand.  If I understand correctly:
1.  The dose collected on our Enviro TLD's can be subtracted from the dose collected by personnel TLD's stored on site.
2.  Some sites (including prototype) store personnel TLD's in badge racks

Sounds like we could store our TLD's at work in a shielded rack and not subtract background.  Or we could store the TLD's in a non shielded rack and subtract background.  Either way, the recorded exposure for each person would be quite a bit lower than if they take their TLD's home.  Does this sound right to anybody or am I totally misunderstanding the way background is corrected?  Thanks for the help guys.

1. Subtracting background has got to be more efficient, accurate, and cost-effective than shielding. I would not even consider shielding -- there is no need.
2. Without any actual research on the subject I would feel very safe saying the majority (probably > 2/3) of plants keep their TLDs on site.

[Khak-Hater]

Ah McLovin, I believe that perhaps you were slightly confused about a few things.  So, let's discuss further.

First:

but your "holier than thou" attitude automatically turns me off.

I wasn't at all trying to turn you on.  I'm pretty sure there are other forums better suited to that end.

Second:

I don't know any business that would knowingly allow their employees to waste 10% of any company asset.

"Person-Rem" is not a company asset. It is an arbitrary indicator of how well you're practicing ALARA.  Upper Management and auditors love stats, charts, and graphs.  They can't show how conscientiously each of your rad workers and HPs actually practice ALARA in the field, so they love numerical indicators like "person-rem," uptakes, and skin [or personnel] contamination events. Personally, I've seen some really poor RadCon programs with great charts and graphs, as well as some very good ones with poor charts and graphs.  My question is, "What are you emphasizing in your program?".

Third:

I will agree that ALARA is something that needs to be internalized by the site, but as far as I'm concerned, if you aren't willing to realize that nearly 30% of the American population dies of cancer and you need to do everything within reason to reduce your dose, 

I challenge you to put your money where your mouth is.  How well have you monitored the background radiation dose hazards that you and your family receive from natural and other nonoccupational sources?  Personal radiation dose from unlicensed radiation sources can be decreased by over 100 mrem per year in many cases just based upon simple lifestyle changes.  Have you given these any thought?  As a Health Physicist have you made any lifestyle changes for yourself or family, or suggested any to your friends or community?  Exactly how dedicated are you to ALARA? 

I know it sounds like I'm trying to give you a hard time on this, but what I'm really trying to do is provide some perspective.  I simply don't know any experienced dosimetrist or HP program managers who would try to make their ALARA numbers look better by playing games with their TLD racks or background [control] TLDs.  It's a one time reduction that you'll simply factor into your ALARA budget for next year.  The best that it could accomplish is to allow you to put a bullet on your performance eval that you reduced your cumulative dose by some percentage [for a single year, and without any real improvement to your program].

Lastly, something that I failed to mention in my original response is that there are two significant organizational advantages to programatically racking your TLDs each day:
(a) to ease with collection of TLDs for processing; and
(b) to allow for the bizare draconian practice of "pulling someone's TLD" as a form of access control.
The first can be a significant time savings for some programs.  The second always struck me as a somewhat childish way of controlling access (e.g., I don't trust you to obey a direct order to stay out of an area, so I'm taking your TLD away to make sure that you do).

Best of luck to you man,

MGM

[Evilpixie]

We keep our TLDs onsite; we keep control badges on the racks and they are averaged and subtracted as the others have mentioned.  We did a study to determine if it was better to let them go home with peops or if it was better to make them put them in a rack before they went home.  We decided to keep them onsite.  For our site it's a better practice.  We have better accountability for where someone received exposure (ie. we can say that they got it here with more certainty than if we did not keep the TLDs onsite)(we also reduce the chances of someone having their TLD "read" by leaving it on the dash of their car when offsite), we don't have to chase peops down to collect the badges, and a significantly smaller number of badges is lost. 

We don't look at keeping the badges onsite as being part of an ALARA program... it's an administrative practice that supports it.  Dosimetry is one of the things used to prove that a site's ALARA program is effective.  Ensuring that the dosimetry used accurately portrays the amount of dose personnel receive is important to support that program.  Our decision was that keeping them onsite supported this better than if we didn't control them in such a fashion.

Regulators support doing it either way just as long as you have documented justification for your decision... and they agree with your findings, natcherly! 

[number41]

EvilPixie (and others), thanks for the actual useful input.  Like I said, I'm just looking for a way to help us meet goal THIS YEAR.  Obviously, this is not a permanent fix, but I'm doing what I can to suggest solutions for the real problem.  I'm an SRO (candidate) for now, but as a former Navy RCT I feel like I have at least a base knowledge that can help solve some of the problems that my site is having in the ALARA department.  I'm not sure yet if we actually subtract our background or just write it off as inconsequential, but I'm doing the research, and realistically, the important part is that I'm learning more every day about the people at the site and how the organization works.  I really feel like I can make a difference here, so I think that exploring every option is worth a few minutes of my time.  So, for those of you that continue to be helpful, my sincere "THANKS."  For those of you who continue to drag us all down by spewing negativity at every opportunity, all I can say is that I can't wait to be your boss.  Peace ya'll!

[JustinHEMI05]

Wow, Bro, you need to stow that attitude. That last sentence was completely unnecessary and shows that you have a very unrealistic view of your place in commercial nuclear power. An ex-Navy SRO candidate is about as from being someone's boss as you can get. If you haven't figured it out yet, this is a small community and almost everyone in this community knows someone at each site, considering a vast majority of them have been to many sites and move around a lot. To make a statement like that, geez, I am just at a loss for words at this point.

I appreciate what you are trying to do, but really, try not to be a douche while doing it. If you bring that attitude into your quals when you get on crew, you are going to be screwed.

Justin

[number41]

Actually, if you read the whole post, you will see that (once again) I came here to ask an honest question about something.  And (once again) you'll see that someone took the opportunity to treat me like a total jerk just because I'm a nub.  I've never come here looking to make people angry or set the world against me with regards to getting qualified at a plant.  However, I also must say that as far as anybody (besides you and a few others) know, I already could be someone's boss here.  Which is all the more reason why I feel people should just either answer a question or butt-out.  I don't come here to make friends or be the target for other people's problems, but I don't care if I'm talking to Jesus Christ; I'm not going to let someone talk to me like I'm a complete idiot just because I don't have all the answers.  Maybe that's why you can see all of the piss and vinegar I've been spewing in the recent posts............because everytime I come here to ask an honest question, someone acts this way.  End rant......Anyway, how's license class going?

[JustinHEMI05]

Class is going fine. Hard, but fine. I sometimes wish I was in an NLO class because it would be far X infinity easier had I been coming through the commercial "pipeline." And that is my point, stop worrying about dosimetry racks and go get in the plant. Go get dirty, go take some rounds, go participate in some evolutions and tests, go find every nook and cranny. There is enough to see and do that you should be busy the entire time you are there. If you are not and you have time to worry about dosimetry racks, you are effing up. Trust me. Worry about that stuff later.

Justin

[HydroDave63]

but your "holier than thou" attitude automatically turns me off. 

ditto

[SloGlo]

i've bin on sights where dosimeters were racked @ da end of shift in shielded 'n in unshielded racks.  alla sites had racks, boxes, a box two leave yer dosimeters in at da end of shift.  nebber did a job were ya were supposed too take it home at da enda da day. 

[Khak-Hater]

My apologies "McLovin,"

I was slightly confused about your professional position when I responded to your question.

However, I also must say that as far as anybody (besides you and a few others) know, I already could be someone's boss here.

Silly me, I DID think that you were someone's boss, or maybe even someone who knew something about dosimetry or were responsible for its administration.  I definitely thought that you were an HP.  After all, why would I think that someone who's supposed to be in Operations quals would be wasting time that he could spend learning the plant, dreaming up solutions to other people's problems or programs.  Are you avoiding the task at hand?  Did the HPs ask for your help on this issue?  Are you such a super-genius that you have the mental capacity to master learning your plant, while simultaneously solving everyone else's problems [along with leaping buildings in a single bound]? 

Just kidding, I know that you're just trying to help.  One ship, one crew, right?  It's just that I didn't guess your circumstances prior to my response.

It wasn't my intention to respond to you like you were an idiot.  I assumed that you were a peer, and responded as such [much like we HPs will banter over the Linear No-Threshold risk model, opposed and against].  Now that I have a better understanding who you are, and what your intentions were, I realize my mistake.  Next time, I'll try to look at it from all angles prior to launching into a sermon, that, while on topic, is inappropriate material for the intended recipient.

My most sincere apologies,

mgm

[alphadude]

gee its a little chilly in here... get a task force together.. assess why your bkg is so high... STAR your dosimetry procedures..ensure bkg subtract is used,  make a plan and go for it..   giving people dosimetry to take home is ok in some situations. you will have some weird readings, the dog ate it, medical high doses, getting cooked in the sun on the dash, going thru airport x ray (a few percent occurrence) etc. you can change the culture and get better control of the tld but it will take a year or two.  high dose individuals should have their tld watched a little closer than most.

[kp88]

gee its a little chilly in here... get a task force together.. assess why your bkg is so high... STAR your dosimetry procedures..ensure bkg subtract is used,  make a plan and go for it..   giving people dosimetry to take home is ok in some situations. you will have some weird readings, the dog ate it, medical high doses, getting cooked in the sun on the dash, going thru airport x ray (a few percent occurrence) etc. you can change the culture and get better control of the tld but it will take a year or two.  high dose individuals should have their tld watched a little closer than most.

We take our TLDs home.  I don't think that our loss rates are any higher than when we kept them on site.  TLDs aren't great chew toys, but, it does happen.

[SloGlo]

We take our TLDs home. 

yinz are still using tlds?  ya gotta sear yer cotton threads bee four putting dem inna self reeders two?  aye usta hate gitting dat carbon on my fingers. 

[number41]

Sorry everyone for getting so worked-up.  I'm just high-strung! (justin can attest to that.)  Anyway, I finally found-out that our TLD's are corrected for background already, so my idea of leaving them at work in shielded racks wouldn't have been exactly legal anyway.  As for why an OPS nub is rooting around in HP's "bidness" is this:  I'm stuck working as an engineer for a couple of more months while waiting for license class.  Due to an unfortunate turn of events, I'm not working on shift while waiting for class, but that's supposed to change.  Anyway, this whole idea was just something that I thought of one day sitting around the house with nothing to do.  So, thanks for the help guys, and as always, hope I didn't pi$$ anybody off too bad!