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.