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Sponge Blast Decon
« on: Mar 13, 2006, 10:39 »
Harris will be sponge blasting our Internals Lift Rig (Big tinkertoy...rad smearable...unknown fixed...real tight time for decon) at the end of RFO-13.  Work will be done in the lower cavity inside a tent. Anyone got any experience with blasting highly contaminated objects using this system?


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Re: Sponge Blast Decon
« Reply #1 on: Mar 13, 2006, 12:11 »
Just the ends of some RCS pipes. Much better geometry than a lift rig. Make sure your tent is done right, try to configure a suction device for your worksite HEPA that will allow mobility and maximum entrainment at the blast area, have your HEPAS(affore-mentioned one and one on the tent) and media filters as far away from the work area as possible, set up some constant doserate monitoring on your Hepas and media filters, and somehow monitor inside tent airborne with an alarming instrument. Maybe an AMS-4, but you would need to set it up remotely due to doserates in the cavity. With all that suction in and on the tent,make sure to have plenty of inlet air (filtered) available, and dont forget to trunk the discharges of your Hepas up and out of the cavity. Most of all....... Good Luck.


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Re: Sponge Blast Decon
« Reply #2 on: Mar 14, 2006, 09:49 »
Why do it in the cavity? I would think that FME would be a major concern with the sponge and paint chips. I’ve been to Harris; it would make sense to set up in the head stand area. If you want the paint off I would suggest grit blasting, it’s done to LP turbine rotors all the time.

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Re: Sponge Blast Decon
« Reply #3 on: Mar 14, 2006, 12:27 »
For the love of all that is good and tasty DO NOT let the "tight window" push you into taking any shortcuts.  Most of the time, when a setup like this is going to be used, the simplest things get overlooked.  For example, how many times hve you seen somebody "blast" something only to have it end up just as contaminated along with most of the rest of the building?  You know this happens all the time, and it is absolutely not because the tent or hepas were set up wrong.  The real cause is that they jump right into "blasting" when they should be "washing".  If you have "no time for decon" beforehand, when will you have time to decon the entire building afterward?.
If the rig is "rad smearable", remember that anything you can take off with a smear can also be removed with a rag and some water.  Add a little soap to that and you can do miracles.  Get with your chemical control coordinator to make sure you have a detergent that is approved for use in that area.
Just don't get ahead of yourself and blast away.  While the tent and hepas are being set up, get on that thing with some buckets of soapy water.  One good wash is enough.  After that you'd just be burning dose for little reward.  You will find that the blasting will be more effective and cause you fewer headaches if you wash away what can be washed and then blast what is left.  Most of the airborne/contamination-spread problems are caused by that outer grimy layer of loose contamination.
"To be content with little is hard; to be content with much, impossible." - Marie von Ebner-Eschenbach

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Re: Sponge Blast Decon
« Reply #4 on: Mar 14, 2006, 03:58 »
I like BeerCourts idea.....wiping is good
Is it time for coffee yet?


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Re: Sponge Blast Decon
« Reply #5 on: Mar 14, 2006, 05:34 »
Love the feedback!  More details. . . just to let you know, I'm not of the blast now and clean up later brand of HP.  During drain down the decon starts while it's still wet.  After the lower cavity is drained down the deconners are going to low pressure wash and hit the surface with long-handled doodle bugs and then rinse some more.  I still need feedback reference the sponge blast process.  The manufacturer says that it reduces airborne dust 98% (great unless you are blasting rad smearable or whatever we start with). The video shows the sponge material collecting in the corners like a snow drift and the workers sweeping it up with dust pans for reuse (quit laughing!! I shuddered when I saw that, but it gets better.)  The recycling process consists of dumping the used sponge material into a "shaker" which seperates the sponge + crud into sponge + large crud + fine crud.  Each component drops out of a seperate chute into a bucket (I said quit laughing!!) I think we'll try modified thunder jugs. I don't want to become Technician A in the latest OE where HPs all over the country wonder how you could have been so stupid.  I still need info on airborne and contam on a nasty open object.  This job's going to be a hoot!!


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Re: Sponge Blast Decon
« Reply #6 on: Mar 15, 2006, 01:57 »
I used the sponge jet at Enviro-Scare in the late 90's.  It created more work than it was worth.  Are they still collecting it with snow shovels?  It sounds good from the salesman, but it a F*****g mess to deal with.


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Re: Sponge Blast Decon
« Reply #7 on: May 19, 2006, 06:43 »
RFO-13 at Harris is done.  The sponge blast of the lift rig was done on night shift and lasted 15 minutes before it began to perforate the tent...which as it turned out was a good thing.  The air sample was 1.8 E-6.  The painters HEPA filter read 2.5 mrem/hr.  Management called off the job when prestented with photos from the inside and all the nasty survey data.  Back to the drawing board.

Big cudos for the Hurricane Hood.  Works as as advertised as a body cooling device (wink, wink).  The painter came out clean and body count was negative.

A whopping four square feet of material was removed. Four inches of material in the bottom of the transfer drum read 30 mrem/hr.

Lessons learned:

1.  Never let the painters design a tent.  It fit the lift rig like a glove. Yeah, I know...duh!
2.  Sponge blast is NOT dustless.  The tent walls were mrad in the inside (looked like graphite).
3.  We had prefilters over the HEPA hose inlets inside the tent.  Both were black.  One had a softball sized wad of sponge material imbedded in the prefilter.  The sponge is so light that we may have to set up a small room off the next tent and pull from there to decrease the face velocity.
4.  The material collects like black snow on the floor and we used less than a bag of the stuff (~20 lbs).  It also splatters everywhere.  All horizontal surfaces were coated.  Had to vac all the surafces after the fact.  FME concern next outage.
5.  It did strip the paint!  Stripped surfaces were 50K...unstripped 200mrad.
6.  Decon only helps so much.  The lift rig was used during the outage to place/remove the Temporary Reactor Vessel Cover.  We took the opportunity while it was on the floor to decon accessible areas.  200 mrem/hr decon towels and it still read 30-40 mrem/hr fixed.
7.  The sponge material is electrostatic.  The painter came out covered with dust.  The HP was wearing a face shield and cringed as he wiped him down before cutting him out.  He said it smelled like concrete dust.  I can't print what else he said...

Next outage we'll ask for 7-9 days....use a proper scaffold tent...bigger...probably on the reuel floor...maybe a grated floor to allow the material to fall into a pit for vacing. Probably airlines, but the hurricane hoods are definitely slick.  Oh yeah, one more thing...FEAR THE LIFT RIG!!

My comment when we were deep into this was ..."Beats the hell out of doiong weeklys!"


  • Guest
Re: Sponge Blast Decon
« Reply #8 on: May 22, 2006, 09:47 »
wow who's brother in law owned that company. Dry ice blasting is the best for those applications, anytime you add material to a job (the blasting media) you will have a mess.  The physical process of blasting will tell you (no brains needed) that fine particulate will result.  Prewash areas with a dilute ammonia solution, pressure wash, then blast.


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