Chemical cleaning Hx's

[radbrat]

Got a couple of Fuel Pool Cooling/Cleaning Hx's that have had a degrading trend in their heat transfer performance. Had a bid for a vendor to perform (proprietary) cleaning and was subsequently told to perform the restoration of the Hx's "inhouse" and a heck of a lot cheaper. Anyone have any tales to tell about:
1) Chemicals used (this is a BWR with HWC and GEZIP, no NMC as yet)
2) Resins used for cleanup and return to service of water

Most likely fouling mechanism is macro (FME introduced over the years through Fuel Pool skimmer tanks), iron oxide, and possible adherent from chemicals used for reactor cavity decon.

Appreciate any help I can get.

[haverty]

hydrolancing not an option?

[JsonD13]

Did you guys check into hydrogen peroxide?  I am not sure of the chemical implications are with that system, but I know it does a darned good job of getting crud moved out.

[mostlyharmless]

Maybe sodium hydroxide.

[radbrat]

Well...cant use h202, it'll mess up the demin beds, Evil Al suggested red flaming nitric acid, but we decided on oxalic  and citric acid(######tm) with some surfactants in low volume. Needed to set up temp demin vessels and a series of particulate filters. What I was looking for was any OE's on similar jobs in the bizness.

[Marlin]

Well...cant use h202, it'll mess up the demin beds, Evil Al suggested red flaming nitric acid, but we decided on oxalic  and citric acid(######tm) with some surfactants in low volume. Needed to set up temp demin vessels and a series of particulate filters. What I was looking for was any OE's on similar jobs in the bizness.

Using hydrogen peroxide was a common practice. Is there something about your resin beds that is different? When ever it was used the resin was normally changed right afterward due to physical and radiological loading anyway.

[haverty]

Well...cant use h202, it'll mess up the demin beds, Evil Al suggested red flaming nitric acid, but we decided on oxalic  and citric acid(######tm) with some surfactants in low volume. Needed to set up temp demin vessels and a series of particulate filters. What I was looking for was any OE's on similar jobs in the bizness.

I've used nitric acid and citric acid to great success cleaning HX's.

[radbrat]

Using hydrogen peroxide was a common practice. Is there something about your resin beds that is different? When ever it was used the resin was normally changed right afterward due to physical and radiological loading anyway.

Hydrogen Peroxide is a common practice where the dilution factor (PWR's for crud bursts) is ginormous. Arent the demin vessels valved out during the H2O2 add? They usually use 10-20 Liters to the system volume, 200k gals? The RCS (particulate) filters are in line during the crud burst? Demin's will react with high concentrations to hydrogen peroxide, anions are very reactive.

I've used nitric acid and citric acid to great success cleaning HX's.

Halfway throught the job and numbers are looking good.

[Marlin]

Hydrogen Peroxide is a common practice where the dilution factor (PWR's for crud bursts) is ginormous. Arent the demin vessels valved out during the H2O2 add? They usually use 10-20 Liters to the system volume, 200k gals? The RCS (particulate) filters are in line during the crud burst? Demin's will react with high concentrations to hydrogen peroxide, anions are very reactive. Halfway throught the job and numbers are looking good.

[haverty]

Halfway throught the job and numbers are looking good.

Cool. How are you doing it, I'm curious. I made a pump rig to continuously recirculate it, as well as taking the thing out and soaking it. (I imagine the scale of HX's you are cleaning is much much larger then what I'm used to, further adding to my curiosity! )

[JsonD13]

Cool. How are you doing it, I'm curious. I made a pump rig to continuously recirculate it, as well as taking the thing out and soaking it. (I imagine the scale of HX's you are cleaning is much much larger then what I'm used to, further adding to my curiosity! )

As well as to mention, radioactive.  Which is something most in the Navy do not get to mess with.

[radbrat]

Cool. How are you doing it, I'm curious. I made a pump rig to continuously recirculate it, as well as taking the thing out and soaking it. (I imagine the scale of HX's you are cleaning is much much larger then what I'm used to, further adding to my curiosity! )

Sent you a PM.