CANDU & H3

[Sun Dog]

hey guys
just came back from the outage at Point Lepreau
what a great CLEAN place to work......i hardly picked up anything working there almost 4 weeks.....anyways i was in the RB every day for about 9-10 hours in the resparaitor and my final dose was like 25 mRem......by the way its that clean that we are aloud to wear out regurlar clothes in there.....anyways very good place and great people there

I doubt focus is still around, but maybe somebody else could shed a little light on his dated post...

How can a place be considered "a great CLEAN place to work"  if for four weeks you are "in the RB every day for about 9-10 hours in the resparaitor (sic)"?  What activity would require that level of protection in a plant "that clean that we are aloud to wear out regurlar clothes in there (sic)"?

[stormgoalie]

I doubt focus is still around, but maybe somebody else could shed a little light on his dated post...

How can a place be considered "a great CLEAN place to work"  if for four weeks you are "in the RB every day for about 9-10 hours in the resparaitor (sic)"?  What activity would require that level of protection in a plant "that clean that we are aloud to wear out regurlar clothes in there (sic)"?

Because the respirator was for H3 and not airborne particulate.  We have accessible areas inside of our containment buildings at Pickering that have no loose contamination, but have low level H3 so you need a respirator......

[Rennhack]

Because the respirator was for H3 and not airborne particulate.  We have accessible areas inside of our containment buildings at Pickering that have no loose contamination, but have low level H3 so you need a respirator......

Are these "supplied-air respirators" or the standard negative pressure Air-purifying respirators?  Or one of those weird "Tritium Bottle Respirators"?

[stormgoalie]

Are these "supplied-air respirators" or the standard negative pressure Air-purifying respirators?  Or one of those weird "Tritium Bottle Respirators"?

Here we use a negative pressure, half mask, air purifying respirator with a specific cartridge that is wetted prior to use to absorb H3 present in atmosphere.  This is only used at lower levels as ~50% of your H3 exposure is through the skin, at high levels we use an air supplied plastic suit with a hood...

[Motown homey]

Do you really have H3 in concentrations significant enough to require respiratory protection in clean areas of the plant?  If the concentration is that high, have you tried using an Hydrogen scrubber to decrease it?

[Sun Dog]

Here we use a negative pressure, half mask, air purifying respirator with a specific cartridge that is wetted prior to use to absorb H3 present in atmosphere.  This is only used at lower levels as ~50% of your H3 exposure is through the skin, at high levels we use an air supplied plastic suit with a hood...

Please have patience with me.  I am ignorant about the ways of commercial power north of the border.

What is the filter media in this "special cartridge"?  Did the manufacturer designed the cartridge to be wetted?  What is it wetted with?  Do you assign a PF for this respirator/cartridge combo?  If you do, how do you account for the evaporation of the wetting agent, and the reduced effectiveness of the cartridge?  Do you have a bioassay program to assess tritium intake/exposure?  Why the half-face?  Why not a FF (since by your estimate 50% of tritium exposure is by skin absorption)?  What other protective equipment is required (gloves, coveralls, etc.)?

[Already Gone]

Please have patience with me.  I am ignorant about the ways of commercial power north of the border.

What is the filter media in this "special cartridge"?  Did the manufacturer designed the cartridge to be wetted?  What is it wetted with?  Do you assign a PF for this respirator/cartridge combo?  If you do, how do you account for the evaporation of the wetting agent, and the reduced effectiveness of the cartridge?  Do you have a bioassay program to assess tritium intake/exposure?  Why the half-face?  Why not a FF (since by your estimate 50% of tritium exposure is by skin absorption)?  What other protective equipment is required (gloves, coveralls, etc.)?

I don't remember what the medium was, but I seem to remember  PF of 2.  I do not recall ever wetting the cartridge, but it came in a sealed foil package and was only good for about 4 hours.  The bioassay was what you might expect.  It was a bin full of plastic bottles in every washroom.  If your REP required it, you would go once a day, scan the barcode on your TLD, take the barcode sticker from the scanner and put it on the lid of a new plastic bottle, provide about 100ml of last night's Labbatt's, and leave the labeled bottle in the rack.  Then someone from Health Physics (separate from Rad Protection) would collect all the trolleys of bottles to the lab and LSC your dose for the day.
FF was not really an option.  Unless the H3 levels were really low or the trip really short, we wore the air-fed suit.  Considering heat stress, it was a better option.
I don't know how much things have changed since I left, but some areas could be entered in tyveks over street clothes.  The use of an air suit, or work in certain areas required that you strip, put on plant-supplied socks, underwear, coveralls, yellow workboots -- all that BEFORE dressing out.  On the way out, you passed through about 6 different monitors, stripped, showered, put on your own clothes and shoes, and went through two more monitors to get to the clean zone.  You had two lockers -- one for your yellow boots and dirty side stuff, and the other for your street clothes.

CANDU plants are very low dose, low contamination (other than Tritium) and definitely different from a LWR.  98% of my dose was from H3.

http://www.nukeworker.com/study/hp/CANDU_RP_study_info.pdf

[Rennhack]

If you would like to read more about the US DOE approach, read this:

DOE HDBK-1105-2002 Radiological Training for Tritium Facilities

[mostlyharmless]

Here at srs, at one of the few tritium factories in the country,plastic suites are the norm. If not then street clothes are good. Lots and lots of bioasseys. The hazard is low compared to most that we encounter. The tritium good practice handbook Renhack suggests is good. If you really want to know I will contact folks who deal with tritium,both elemental and oxide( it makes all the difference) every day and get back with you.

[retread]

SunDog, why did you change your avatar?  The cute pug was the only reason you had any positive karma.  You're in for it now!!

[stormgoalie]

Please have patience with me.  I am ignorant about the ways of commercial power north of the border.

What is the filter media in this "special cartridge"?  Did the manufacturer designed the cartridge to be wetted?  What is it wetted with?  Do you assign a PF for this respirator/cartridge combo?  If you do, how do you account for the evaporation of the wetting agent, and the reduced effectiveness of the cartridge?  Do you have a bioassay program to assess tritium intake/exposure?  Why the half-face?  Why not a FF (since by your estimate 50% of tritium exposure is by skin absorption)?  What other protective equipment is required (gloves, coveralls, etc.)?

We used to have a cartridge, the one Beercourt is referencing, that was made, pre-wetted, by MSA. Our new cartridge is made by Mitchell and is a plastic shell with a corrugated paper in a spiral pattern that you have to wet prior to use with potable water. This cartridge was specifically designed for our use.  We have a usage time limit, but they can be re-wetted to take care of evaporative loss. Yes we have a urine bioassay program and all personnel are assigned a specific frequency based on the probability of exposure.  Also, most of our REP's that are used in an H3 environment have a bioassay requirement at end of shift.  There is no benefit to a full face respirator to based on the dose gained by the time added while wearing the respirator. In our "free released" areas inside containment, the only places in the plant where one can encounter a tritiated atmosphere in street clothes, have no RPPE requirements per se.  Of course in there are other forms of contamination present anti-c's etc. are worn as needed.

[stormgoalie]

Do you really have H3 in concentrations significant enough to require respiratory protection in clean areas of the plant?  If the concentration is that high, have you tried using an Hydrogen scrubber to decrease it?

Inside containment we do have driers that lower the H3 concentrations, but anything above 1 MPCa or ~1 DAC as they both equate to ~2.5 mRem/hr internal exposure requires respiratory protection.  Biggest thing to remember is that we only encounter H3 under normal circumstance inside containment and NOT outside of containment in the hallways.

[Rennhack]

http://www.nukeworker.com/study/hp/CANDU_RP_study_info.pdf

Troy,

The file you linked to is damaged, and I can't find an undamaged version to replace it.  Do you know where I could get an undamaged version?

[hatrai07]

Agree with most of what Beercourt said except that Candu is low dose.  At my station, the dose is very high (over 100 rem /unit) with less than 10% dose attributed to H3

[mostlyharmless]

The reactors at srs were heavy water moderated , so every line break associated with primary has tritium associated with it. As I understand it there is no practical way to significantly reduce tritium emission during job coverage,it is, after all, hydrogen and behaves the same way,so its just redirected and monitored. Plastic suites only go so far. If tritiated water splashes on your suite you have a short period of time to remove the splash and the suite. The bioassay becomes more like a job coverage tool.
The real time air monitors are big ion chambers,the air gets sucked through and the week beta interacts inside. Their are handheld monitors as well. And the bubbling of air through a scent. cocktail.
I'm glad this came up,H3 is not something a lot of us get to work with. I would like to know more about how the candu hp handle it.

[mostlyharmless]

Along with H3 control I also would like to know how individual fuel bundles are removed with the reator on line ,how is this covered?

[stormgoalie]

WOW, this thread is going to become a good teaching session on H3 .

As far as how we monitor H3 concentrations we have several methods:

1) Remote Area Tritium Monitors (RATM's) which are essentially a flow through, gamma and noble gas compensated, series of ion chambers that read out directly on a reader board outside of containment or locally on the instrument.

2) Semi-portable Tritium Monitors (SPATM's): Essentially a portable instrument inside a housing that is moveable to where we need it.

3) Portable instruments

4) Passive air samples which are counted in a Scintillation counter.

Being wetted by tritiated water carries the same hazards as mentioned in a previous post so as part of our REP we address the hazard by requiring double plastics when the possibility exists of coming into direct contact with the water.  We also have very stringent bioassay requirements to assist us in monitoring workers with results usually available with 24hrs of exposure and less if we suspect a wetting/uptake has taken place.

As for coverage for re-fueling that's easy, none.  It is all done remotely and the refueling machines and their associated vaults are access controlled with no entry during fueling operations.

[Marlin]

   I have had to package H3 contaminated waste from DOE facilities that you might think would have none. Temperature and pressure changes seem to make it airborne from the water and oil that it was bound to. I had to be careful to seal the containers well for shipment to prevent "offgassing" during handling at the landfill. During demolition of many older buildings H3 exit signs (15 to 30 curies) are encountered.

[stormgoalie]

   I have had to package H3 contaminated waste from DOE facilities that you might think would have none. Temperature and pressure changes seem to make it airborne from the water and oil that it was bound to. I had to be careful to seal the containers well for shipment to prevent "offgassing" during handling at the landfill. During demolition of many older buildings H3 exit signs (15 to 30 curies) are encountered.

We do perform H3 smears on metals that come out of areas that have a tritiated atmosphere should Health Physics require them.  Interesting to bag up something, monitor it with a portable H3 meter, see nothing, come back a couple of days later, and viola H3 has reared its head.....

Remember disposing of many many H3 Exit signs when working at the Lazy H.....

[mostlyharmless]

Sounds like H3 monitoring is similar to srs. H3 is a difficult thing to handle. As for refueling, no leaky fuel? Is it moved through air? I have a report (will share when I make a file out of it) of the assessment and cleanup of a melted fuel bundle after a delay during movement. The release was about 85K curies. A lot of the clean up done remotely. I work in this area routinely. I find it incredable that this is so. Thanks for the posts,anything more on the CANDU is much appreciated.  MH

[stormgoalie]

Sounds like H3 monitoring is similar to srs. H3 is a difficult thing to handle. As for refueling, no leaky fuel? Is it moved through air? I have a report (will share when I make a file out of it) of the assessment and cleanup of a melted fuel bundle after a delay during movement. The release was about 85K curies. A lot of the clean up done remotely. I work in this area routinely. I find it incredable that this is so. Thanks for the posts,anything more on the CANDU is much appreciated.  MH

Good questions! Firstly no it is not moved through air, well at least most of the time.  The fueling machine becomes a part of the PHT system when locked on channel.  Once loaded with spent fuel it has an onboard fuel cooling system that is also tied into a remote heat exchanger to cool the fuel while it sits in the machine.  It is then unloaded into a conveyor system with water sprayers that cool it until it is under water in the transfer tunnel and then in the IFB.  As I am not a fuel handling expert I may be a bit off in the details, but the basics are correct

[Rennhack]

I know this is off topic and everything, and I'm sure some one will call me a troll...

But I never realized that The Queen of England is also the Queen of Canada, as well as 15 other countries.

[RDTroja]

I know this is off topic and everything, and I'm sure some one will call me a troll...

But I never realized that The Queen of England is also the Queen of Canada, as well as 15 other countries.

Slept through a lot of your school years? 

All you have to do is look at Canadian Money... Her picture is all over it.

[Marlin]

I know this is off topic and everything, and I'm sure some one will call me a troll...

But I never realized that The Queen of England is also the Queen of Canada, as well as 15 other countries.

OK      



Did I ever say   for all the   s

[Rennhack]

Slept through a lot of your school years? 

1. I got D's and F's in school.
2. I don't remember those years.
3. I went to a Lutheran School, the only thing they instructed us about was the Lutheran God, and a little about the Catholic God.  Nothing about Canada, that I remember, except the names of the provinces, and their capitols.  Which I also don't remember.

Speaking of Canada... did you guys see my posting about i3?

[Rennhack]

SunDog, why did you change your avatar?  The cute pug was the only reason you had any positive karma.  You're in for it now!!

He changed it because he is our resident TiT (Troll-in-Training).  Don't you keep up with these things?

[Already Gone]

Troy,

The file you linked to is damaged, and I can't find an undamaged version to replace it.  Do you know where I could get an undamaged version?

Did you get that fixed yet?

[mostlyharmless]

Sounds similar to haw it was done hee. Keep in mind these were target assemblies and the reactors were built in the early 50s. Are the candadians still using natural enrichment fuel?
Today I read about a technique for driving off H3 from contaminated soil and concrete. You enclose it and heat it up to ~200 degrees F and bake it for about a weak then sample for H3 to confirm removal. The H3 is released to atmosphere.
We need an off topic monkey,similar to the trunk monkey. Nascar help us. Not,repeat not ,calling you a monkey.

[retread]

He changed it because he is our resident TiT (Troll-in-Training).  Don't you keep up with these things?

Sorry, not in the clique yet.  Trying though.

[Sun Dog]

He changed it because he is our resident TiT (Troll-in-Training).  Don't you keep up with these things?

Got what I got the hard way
And I'll make it better each and every day
So sonny don't you fret
Cause you ain't seen nothing yet


I'm a troll man
I'm a troll man

[Rennhack]

Did you get that fixed yet?

I probably won't be able to fix it till this weekend.

[stormgoalie]

Sounds similar to haw it was done hee. Keep in mind these were target assemblies and the reactors were built in the early 50s. Are the candadians still using natural enrichment fuel?

Yep, still using Unat for most fuel.  The Bruce plants are now using a new, slightly enriched, fuel bundle to enhance control due to the positive void coefficient that the CANDU design has.  The new generation of CANDU plants will actually us a light water HT system, D2O Moderator system, and slightly enriched fuel to enhance performance and provide better safety margins.  Will also have the great byproduct of reducing our H3 exposure as well

[stormgoalie]

I know this is off topic and everything, and I'm sure some one will call me a troll...

But I never realized that The Queen of England is also the Queen of Canada, as well as 15 other countries.

She even has a representative in Canadian government, the Governor General, who is the personal represetative of the Queen.  Here is a better explanation: http://en.wikipedia.org/wiki/Governor_General_of_Canada