radiological conditions

[wlrun3@aol.com]

   ...are these radiological conditions standard in the industry...


      Cavity Decon (50 OW - 5 CW) 4 = 180 mrad/hr/100 cm^2

      SG Channel Head 10 rem/hr GA / 1 hr/60 min = 16.7 mrem/min

      Protected Area Yard = 10 urem/hr

[retired nuke]

I don't know about standard, but none of them would raise my eyebrows if I was to encounter them at an appropriate time.

First S/G I went into was about 3x that hot...

Depending upon the cavity, SFP water chemistry and fuel conditions, I've seen worse in a cavity, seen better...

Seen PA yard from 7-30, depending how close you were to the Turbine....

But those numbers are in a normal range....

[Bonds 25]

While 10 micro rem/hr is very low in general, it seems a little high for a PWR (no turbine shine).  I would say 10 rem/hr at the channel head is a little high for today's standards (of course Ive seen a lot higher) 120 mrad/100cm2 seems about right as far as pre-cavity decon levels go.

[Already Gone]

That explains 11 Rem/hr contact being the hottest CRD pulled while I was covering changeout under vessel.  My very next outage was Quad Cities, 400 Rem/hr.  I did take my hottest smear ever while at Fermi though, RWCU valve inside the steam tunnel....80 Rad/hr/100cm2.  Valve looked like part of a sewer line.

Have I been out of the tech business too long,. or have they come up with a new meter?  The last open window instrument I ever used only went up to 50 R/hr.  How could you get 80 Rad/hr?

[Already Gone]

   ...are these radiological conditions standard in the industry...


      Cavity Decon (50 OW - 5 CW) 4 = 180 mrad/hr/100 cm^2

      SG Channel Head 10 rem/hr GA / 1 hr/60 min = 16.7 mrem/min

      Protected Area Yard = 10 urem/hr

Bill, most of the time that 50 OW would be 50 mRad/100cm2 since it is not common to BCF a smear.  So, based on my fading memory, this is s pretty clean cavity post refuel.  The channel head dose rate is at the low end of the range (considering that they were 50 - 100 R/hr back when I started the business, and 500mR/minute was considered relatively low.)

[Bonds 25]

20 Rad/hr/100cm2 times Beta correction factor (4) equals 80 Rad/hr/100cm2.

[Bonds 25]

I cant remember one plant (Ive been to 18) where a beta correction factor wasnt used on a smear. 

[wlrun3@aol.com]

Bill, most of the time that 50 OW would be 50 mRad/100cm2 since it is not common to BCF a smear.  So, based on my fading memory, this is s pretty clean cavity post refuel.  The channel head dose rate is at the low end of the range (considering that they were 50 - 100 R/hr back when I started the business, and 500mR/minute was considered relatively low.)

   ...troy, you've been gone too long...you continue to be mourned by everybody from salem to prairie...

   ...thankyou for the upfront info on hope creek, by the way...

   ...exelon does the bcf mrad per 100 now and rps expectations are to mrad above
300K...

   ...the smear example was the common mid cavity decon from last limerick...

   ...the bowl dose was GA palisades...

   ...the yard was peach...


   ...it seems that the consolidation and standardization we have been witnessing in the industry has not only affected outage duration, length of runs and general predictability of outages but also radiological conditions...

   ...i am seeing less extremes, either high or low...

   ...the reason for my post was to get a sense of what is now being seen industry wide and, if i am correct, to come to some conclusions about why this is happening...

   ...the days of 50 R bowls and rad smearable cavities looks to be a thing of the past...like pics and scba power entries...

   ...good to hear from you again...hope all is well...

   bill

 

[retired nuke]

I cant remember one plant (Ive been to 18) where a beta correction factor wasnt used on a smear. 

VY

[wlrun3@aol.com]

I cant remember one plant (Ive been to 18) where a beta correction factor wasnt used on a smear. 

   ...House Dad from VY...

   ...is Entergy procedurally consistent in the non mrad smear counting...

   ...how does VY, and Entergy in general, report greater than 500 K...

   ...by the way, thankyou for the help with the iodine at Palisades last outage...

   ...at palisades, with 3 sets of procedures, rp management expectation is at roughly 200 K you use RO2 with Entergy procedure given flat 4 BCF which is also on the meter...reported mrad/hr/100 cm^2...

   ...palisades, outage 3/9 with one rcp impeller swap, has 12 returnees, half short contract techs for outage, and a 3k bonus...

[Already Gone]

I cant remember one plant (Ive been to 18) where a beta correction factor wasnt used on a smear. 

I guess my question is: why?

Who cares what the "dose rate" is on a smear?  The OW reading is proportional to the level of contamination (most plants have a thumbrule for that), so why take the extra and totally meaningless step of converting that to a dose rate (which will also be directly proportional to the level of contamination)?  We all know from experience the the beta reading on a smear bears no relationship at all to the beta dose rate on the component itself, (I'm not exactly sure why or how the reading on a smear can be higher than the direct reading, but it always seems to happen that way.) but is only significant as an indication of the level of contamination.

My next question would be: why would you take a smear on something so contaminated?  Why would you reach your hand into such a valve, only to retrieve a sample of what you already know (or should have known)?  Yeah, okay, maybe you didn't know exactly how many mRads or Rads were going to emanate from that smear... but did it make a difference?  Did you dress the workers any differently or establish any rad. controls any differently for that 20 (or 80 if you prefer) Rad smear than you would if it read 1 or 4 Rad/hr/100cm^2?  Most probably, you (being a competent tech.) already established the maximum level of protection at your disposal before anyone ever loosened a nut on the valve.  So, the question remains:  why would you expose your hands, skin, and eyes to the internals of that valve and drag out a sample of crud - risking the spread of contamination and unnecessary exposure to yourself - just to get an answer that was totally irrelevant?

Let's get real.  We have several modes of operation.
1. <detectable -- no clicks on a frisker  -- the comfort zone.  We all feel confident that the item/area is clean.   NO Protective measures required.

2. <1k ( or whatever your plant's release limit is ) -- the legal zone.  We will remove or relax controls in such an area as long as it is under the general controls of the RCA, or there is no potential for the levels to increase.  We are not totally comfortable here, but are legally justified.  We just take a little extra care in this zone, just not so much to make our lives difficult if we can avoid it.

3.  1k to 100k.  -- The controllable zone.  We keep things as tidy here as we can, but aren't going to make anybody suck rubber.  We keep the levels and spread of contamination under control.  The level of vigilance and frequency of decon is proportional to the contam. level.

4. > 100k .  -- The no-kidding zone.  We treat everything from here up with respect.  We will actually take the time to get this stuff deconned before working on it.

5. >500k -- the "mRad smearable zone"  This is as bad as it gets even if it gets worse.  There is no level of protection greater than the one we use here.  We cover them constantly, hang HEPA hoses in their BZ, remind them to change gloves at regular intervals, pre-stage catch basins, arrange deconner and trash removal support,... etc.  In other words, this is where we do our jobs.  There is no proportionality in this mode.  Once we get above the level where a frisker can be used to count the smears, we have basically reached the plateau.  Since we are not going to treat things any differently at 100mRad/hr/100cm^2 than at 100 Rad, there is no point in distinguishing between the two.  Every tech with a brain knows whee this zone is without taking any smears.  Any piping system that comes directly out of the reactor (RWCU, RHR, RCS, etc.) is going to be in this zone - period.  Taking a smear here is the equivalent of taking a smear inside a S/G bowl or under the Rx head.  There is just no justification for it.

So, why do we take those smears when we should be having the initial decon done first?  Because we loooove to tell war stories.  80 Rad/hr/100cm^2 sounds so impressive, doesn't it?  But I'm waiting for someone to show me the RWCU valve that you were talking about in some plant where it is NOT that contaminated.  Now, THAT will impress me.

[Bonds 25]

I believe is was basically a RWCU drain line that is hardly ever used.  Not quite sure RP supervision or the NRC would of taken the "well its RWCU, so I didnt take a smear to confirm what the contamination levels were inside the valve they breached and were about to repair because I knew it was gonna be >500K dpm/100cm2" excuse.  Plus last I knew, during a valve breach (especially unknown conditions since they havent opened the valve in many, many years) smears must be taken, along with dose rates and air samples. I know Fermi and the plant I currently work at  >500K dpm/100cm2 is not an acceptable entry on surveys.  We were expecting low-mid mrad/100cm2, not RAD, and in a very small confined space (like Fermi's steam tunnel) there is a big difference.  They actually talked about just cutting it out instead of repairing the flapper based on the RAD conditions alone. However they deconned the best they could, fixed the flapper, put the valve back together and it passed testing. In 12 years Ive only seen RAD/100cm2 a hand full of times and nowhere near that level, so it was quite surprising to me to say the least. Ive covered a lot of RWCU work in my years, I was (unfortunately) the "RWCU man" at my plant last outage.  Even direct drain line valves from our RWCU heat exchangers were nowhere near RAD/100cm2 smearable and our plant is nowhere near as "clean" as Fermi. Actually we have one of the highest source levels in the nation. 

[Already Gone]

Well, every reactor has a valve like this.  It's the first check valve coming from the loop - RCWU, RHR, whatever.  Simple answer is that they are all about the same and the contamination inside is not the issue.  What you need to be looking for are things that are inside the valve that it shields before you breach it - little chunks of fuel or blobs of crud with extremely high dose rates.  (Of course, I don't have to tell you this) There is no way that taking a smear helps you to find those.  All it could do is get your hand in contact with them or get them dragged out into the open on your smear and glove.

The NRC???  Since when has the NRC EVER cared what the contamination levels inside a system were?  If it is inside a properly posted and barricaded area, it can be a kiloRad/hr/100cm^2 for all they care.  And supervision are usually the ones who tell you not to f#@!< around taking a smear in there.  If they aren't, then they shouldn't be supervising that job.

The only safe way into one of these messes is to "decon your way in".  You wash everything before you touch it.  This results in the first smear being on the parts as they come out - long after they have been wiped down a bunch of times and sprayed a bunch more with demin water.  Even then, a smear is a waste of time, because you never want to let something that contaminated to get dry.

The regs don't say s#!+ about smearing valves.  They just say that you have to assess the conditions where work will be performed.  In that case, it is perfectly acceptable to asses that they are too contaminated to smear.  You can make that determination based on the contact dose rate on the outside of the valve.  It is pretty fundamental.  But, they stopped teaching fundamentals a few years back and just hoped that 6000 hours of Jr./decon/dosimetry time and an 80% on the NEU would replace actual training.

The survey of course needs to be written with actual levels, but nobody says that it has to be taken on parts that are not yet cleaned.  The real information you need is what is the condition of the material that humans will be exposed to while working on them.  So, you record the dose rates (beta and gamma) as the valve comes apart, and you record the smear levels on the parts at the work bench before Charlie the valve tech. starts brushing, grinding, or hammering on them (or even worse - putting a solvent based chemical on them).  By that time they should be deconned considerably below the Rad/hr smear level.

This is the same principla as every other survey you will ever do.  You meter your way in and smear your way out.  It's the only way to avoid getting a nasty surprise.

I think that we all forget a lot of the time that the function of the job is radiation PROTECTION and not radiation DETECTION.  The detection only makes sense when it serves a purpose.  Smearing the inside of that valve before it is flushed serves no purpose at all.  It just makes for a good story.  Of course, I have taken that smear before.  All of us probably have.  The reason we did was that we didn't think to ask ourselves why we were bothering to do it.

So, what is wrong with injecting some common sense into this and stopping to ask ourselves if it is really necessary to do some things just for the sake of doing them.

[Bonds 25]

Just following what I was told buddy.  It was a very small valve on maybe a 4 inch line, and like I said a drain line that is very rarely ever used. Not your normal RWCU system breach. End of shift breach with niteshift taking over.  You think I should of had them breach the valve, not take a smear and give the niteshift techs a survey without any contamination levels?  The NRC has something called failer to survey, we just went through a finding because a worker got contaminated because a tech didnt survey inside a drum.  Imagine if the workers happened to get contaminated during the valve breach, and I had no contamination levels because I didnt survey knowing the valve was gonna be >500K dpm/100cm2.  I understand the point you are trying to make, and maybe thats how it use to be, however the NRC and even more INPO takes contamination and PCI's very serious right now.  I smear all valves and unknown conditions when they exist, this saves MY ass if anything ever goes wrong.  Saved my job at Ft Calhoun during their PZR instrument line cuts (again RAD/100cm2) during their PZR changeout.  Workers, and myself got small uptakes and contaminated (small area, unknown conditions) and guess what supervision's 1st question was...what were the contamination levels upon breach?  Sometimes is not as easy as 1. breach 2. decon 3. work, especially when you find yourself covering a very uncommon evolution.  However I understand your point, and yes in many situations your method can be done, but right now it seems that being an HP is about covering your ass, because when the shit hits the fan, we are easy targets.

[Already Gone]

Point taken --CYA.  Sigh.  Glad I have a job that I can do without just going through the motions.

[Brett LaVigne]

These levels seem basically normal with the exception of the channel head dose rates. Typically they are below 6 R/hr and more routinely I have seen in the range of 2 - 4 R/Hr.

As far as Beercourts comments on beta correction factors...while your arguments are rational, they really don't matter. Different utilities require different math. Some will have you record only the open window reading as the "mrad/hr/100cm2" and some will have you do the conversion. It really doesn't matter in the end what we think is right, as rent-a-techs we are required to document the information like the utility requires. I recently took a smear during a valve breach that was over 100Rad/hr/100cm2 (corrected). It was reading nearly 1 R/hr gamma and I believed that in that instance, the dose rate was important (on the smear at least). Some plants like to know the beta to gamma ratio because it can be an indicator of different types raioactive stuff in thier system (that was a very technical way of saying it). Generally it is all going to be relative, and who cares, but some plants are just that anal...what ever, where is my paycheck. I think we have strayed a bit from the original question with too much technical mumbo jumbo. The guy just wanted an answer to a simple question.

[wlrun3@aol.com]

   ..." The guy just wanted an answer to a simple question."...

   ...thankyou...

   ...my original idea was to start an ongoing forum topic that could be accessed to find out what the current or recent radiological conditions are or recently were at the critical locations at the 104 reactors in the US...

   ...bowls, canals, cavities, drywells, etc...

[Already Gone]

Different utilities require different math. Some will have you record only the open window reading as the "mrad/hr/100cm2" and some will have you do the conversion. It really doesn't matter in the end what we think is right, as rent-a-techs we are required to document the information like the utility requires.

+Karma for that!

 

I recently took a smear during a valve breach that was over 100Rad/hr/100cm2 (corrected). It was reading nearly 1 R/hr gamma and I believed that in that instance, the dose rate was important (on the smear at least).

Yes, of course.  You wouldn't want that thing laying in an open trash barrel without knowing the level.

 
 

Some plants like to know the beta to gamma ratio because it can be an indicator of different types raioactive stuff in thier system (that was a very technical way of saying it).

There are lots of ways to find that out without trying to count a smear that is too hot to use any of the lab instruments on.  You'll get the same ratio on a much cleaner smear than one that needs its own HRA postings.   Besides they already know their ratio of Beta/Gamma or else they wouldn't be able to calculate the BCF to begin with.  So, correcting a reading assumes a ratio already - unless they just use the default value of 4.  But then, the corrected number is still meaningless because it just adds an unnecessary factor into the business of trying to figure out the level of contamination.

 

Generally it is all going to be relative, and who cares, but some plants are just that anal...what ever, where is my paycheck. I think we have strayed a bit from the original question with too much technical mumbo jumbo. The guy just wanted an answer to a simple question.

We do that a lot here.  It is what keeps the discussion interesting and fun.  We would all do well to remember that this is an informal area to share thoughts and ideas.  It isn't a classroom.  Besides, Radiation Protection is not an exact science anyway.  No matter how many samples or readings we take, it is all based on statistical models that never apply to any one human body in the first place.  Unless you happen to resemble Reference Man - in which case you are biologically incapable of life.

[Marlin]

I hope anyone handling these high smears took into account the difference in the actual to indicated dose for their exposure while evaluating contamination levels, or at least used remote handling gear.

[Dwayne]

OKam back...looking for a job!

[Marvin]

Beercourt, where were you 20 years ago when I was taking those hot smears?  I couldn't agree with you more.  Makes me wonder why we did the things we did for so long and no one asked "why".  There's no telling how much dose my hands have and I'm sure there's more than one tech out there that's wondered what their actual extremity dose is.  It's good to see that there's folks in the industry that are actually beginning to insert conscious thought into the process rather than blindly collecting data for the sake of collecting data.

[RDTroja]

Beercourt, where were you 20 years ago when I was taking those hot smears?  I couldn't agree with you more.  Makes me wonder why we did the things we did for so long and no one asked "why".  There's no telling how much dose my hands have and I'm sure there's more than one tech out there that's wondered what their actual extremity dose is.  It's good to see that there's folks in the industry that are actually beginning to insert conscious thought into the process rather than blindly collecting data for the sake of collecting data.

20 years ago he was probably the last person that had his hand in the valve before you did... or maybe the next one after you. Much of his wisdom comes with the experience (and advancing years) we are all accumulating. We all have been in situations where we put our hands into places they never should have been and wondered what the hell we were doing it for, but we were told we needed the information so we kept doing it. Some of us got smart enough through experience to question the practice or even refuse to do it. Unfortunately very few of the people that were rebellious enough to question the validity of gathering such data were invited to become supervisors (or they were smart enough to refuse the position) so the practice continues.

War Story Alert

Although I did not purposely put myself into the position to get a good story out of it, this happend to me nonetheless. At a certain plant with a bad reputation in NY in 1978 I was sent to the RHR pit (never a more aptly named location) for a survey. There was one working light in the collection of three (four?) rooms and it was giving up quickly, so there was an eerie feeling to the place to begin with. As I moved into the room, I noticed the was oil on the floor... not spots of oil, but oil you could measure with a dipstick. That was my first sign of trouble (not my last.) The G/A dose rate in the 'foyer' section (no pumps or significant piping) was a few hundred mR/hr. Bad sign number two. I leaned down a little and noticed that the dose was higher near the floor than at waist level. Bad sign number three, since there was nothing down there but lots of oil. I decided that I was going to abbreviate my survey to save my dose -- and because walking in half an inch of oil should generally be avoided -- but I figured I should at least get one reading in the room where the pump that was to be worked on was located. As I glided into the room (afraid to pick my foot up for fear of slipping) the needle on the RO-2A was moving toward the 5R mark and I realized I was no longer in control of my motion -- I was moving toward the floor drain near the pump propelled by gravity and lack of friction. I very slowly turned and 'skated' back toward the door and out of the room... survey complete (to my satisfaction, anyway.) When I got to the step-off pad, I took a dose rate on the bottom of my rubber shoecover just for the sake of knowing... it was about 1R/hr, closed window. I threw the shoecovers into the room and went back up the hundred or so stairs to the main level.

At the same time I got to the top of the stairs my supervisor was walking by and I told him if he tried to send me back down there he would be missing one technician from the staff. He told me to calm down (I was calm, but serious) and to go write up my survey. When the house staff asked me where my smear results were, I told them the whole story and they repeated their question. They couldn't grasp how I could say that contamination levels were meaningless down there given the conditions. They were about to tell me to go back and take some smears when my supervisor intervened and got me out of the room before I repeated my previous offer. I stayed and finished the outage and was invited back (foolishly I returned for a very brief stay, but that is another war story.) Apparently there was someone further up the chain of command that realized that the situation called for decon, not smears.

End of War Story

Moral of War Story: Intelligent people confronted with new concepts (e.g. Why do we need to know how many Rem the smears would be?) can usually be persuaded to let go of old ideas. Sometimes the trick is finding intelligent people in charge.

[Brett LaVigne]

I hope anyone handling these high smears took into account the difference in the actual to indicated dose for their exposure while evaluating contamination levels, or at least used remote handling gear.

Here is the field method of counting a smear that you thought was going to be in the mrad range and it turns out to be 1R/hr gamma and 27Rad/hr beta while you are standing in a 400 mr/hr work area.

1. Take the smear
2. walk over to the low dose area (in this case 5 steps away and 150 mr/hr)
3. Lay the smear down and hit it with the meter.
4. Say...Holy crap! that's a really hot smear, better put it in the bag and set it aside.

Total time with smear in hand...bout' 8 - 10 seconds.

It is great to have things in place to minimize dose in a perfectly planned scenario. But when your guys are working in 400 - 600 mr/hr and you get slapped in the face with a smear that is WAY hotter than anticipated, you have to automatically default to the "time" method of reducing exposure. What was amazing to me in this whole thing was that the house wasn't really all that shocked and was ok to proceed as planned. Did I say...planned? These guys showed up with an extra set of pc's and face shields and we did a little pre-job just before walking in to do the job. Did I also mention that this was in the steam tunnel and not the 2nd level of the drywell where you might think from the dose levels? It made me cover the job a bit differently from that point on but we were expected to continue on. It has been years since I have seen levels like that...Ahhhh, it's like being a kid again...It will probably be ok not to see that ever again.

[retired nuke]

   ...House Dad from VY...

   ...is Entergy procedurally consistent in the non mrad smear counting...
count it on appropriate instrument (considering needed MDA, field check, etc) and document what you get.

   ...how does VY, and Entergy in general, report greater than 500 K...
Survey procedure says to document smears counted with a dose rate meter as mRad/hr. I usually go for the RO-20 if the frisker hits 100k, or when I suspect it before I leave the jobsite. Don't want to drag that stuff back to the count room (I've seen it done... )

The survey procedure doesn't specify to use the BCF that is in the instrument procedure...I agree with other posters that it's pretty much not useful to use BCF for smears. It is usefule to use BCF for exposure. I will take a beta survey when I open a system, for exposure / posting for the workers. Use the BCF there.

   ...by the way, thankyou for the help with the iodine at Palisades last outage...
No prob - remember Palisades from '93 fondly

   ...at palisades, with 3 sets of procedures, rp management expectation is at roughly 200 K you use RO2 with Entergy procedure given flat 4 BCF which is also on the meter...reported mrad/hr/100 cm^2...

   ...palisades, outage 3/9 with one rcp impeller swap, has 12 returnees, half short contract techs for outage, and a 3k bonus...
Sounds busy and hot...I remember an RCP impeller swap at CR3 - wrap it, tag it, drive it around the berm on a cherry picker to RW...nightshift of course..

[Marlin]

Here is the field method of counting a smear that you thought was going to be in the mrad range and it turns out to be 1R/hr gamma and 27Rad/hr beta while you are standing in a 400 mr/hr work area.

1. Take the smear
2. walk over to the low dose area (in this case 5 steps away and 150 mr/hr)
3. Lay the smear down and hit it with the meter.
4. Say...Holy crap! that's a really hot smear, better put it in the bag and set it aside.

Total time with smear in hand...bout' 8 - 10 seconds.

It is great to have things in place to minimize dose in a perfectly planned scenario. But when your guys are working in 400 - 600 mr/hr and you get slapped in the face with a smear that is WAY hotter than anticipated, you have to automatically default to the "time" method of reducing exposure. What was amazing to me in this whole thing was that the house wasn't really all that shocked and was ok to proceed as planned. Did I say...planned? These guys showed up with an extra set of pc's and face shields and we did a little pre-job just before walking in to do the job. Did I also mention that this was in the steam tunnel and not the 2nd level of the drywell where you might think from the dose levels? It made me cover the job a bit differently from that point on but we were expected to continue on. It has been years since I have seen levels like that...Ahhhh, it's like being a kid again...It will probably be ok not to see that ever again.

Those little surprises make the job fun as long as you can keep control and don't end up on the wrong side of the table during the post job breifings.