SV: [ RadSafe ] Vermont Yankee leaking tritium --- time to panic(?)

Fri Feb 5 01:35:02 CST 2010

Hi,

About tritium economy... Speaking at least for a BWR. There are three major sources of tritium in a nuclear reactor:

- Neutron capture in deuterium (lots of it, but low cross section, ca 5E+6 Bq/MWt/month) and neutron capture in Li (not as much of it, but high cross section). About 1 ppb of Li in your reactor coolant would give you similar amounts of the tho activation paths.

- Ternary fission in the fuel (2E+10 Bq/MWt/month). This can reach the coolant only during fuel failures but the release tends to be very small.

- Neutron capture in B and Li in control rods. 3.5E+9 Bq/MWt/month, mostly from the rods that are actually used in the core. Leaking control rods cause notable increases of tritium in the coolant.

Most of the tritium that is released, is released to water, the rest to the air. The choice is between higher releases or a build-up of tritium in the coolant (concentration goes down as water is replaced). Heavy water reactors tend to have enormous tritium inventories due to more deuterium that can be activated, plus they save water more carefully. A typical release to the environment would be 2E+7 Bq/MWt/month of which perhaps 80-90% goes to air. All numbers are of course very sensitive to varying amounts of control rod damage, Li concentration and water economy.

All numbers are from an overview of BWR tritium production ordered by ABB Atom in the late 1990s (ALARA Engineering 99-0030R). There is an updated version or that report around as well.

Mattias Olsson
Forsmark NPP, Sweden

-----Ursprungligt meddelande-----
Från: radsafe-bounces at radlab.nl [mailto:radsafe-bounces at radlab.nl] För JOHN.RICH at sargentlundy.com
Skickat: den 2 februari 2010 18:12
Till: Brennan, Mike (DOH)
Kopia: radsafe at radlab.nl; radsafe-bounces at radlab.nl
Ämne: RE: [ RadSafe ] Vermont Yankee leaking tritium --- time to panic(?)

MIke, 

I'm working with an old man's memory here, but I think the major tritium 
removal mechanism at PWRs is spent fuel pool evaporation.  PWRs generate a 
fair amount of tritium (lithium chemistry??), they just dispose of it in a 
a variety of ways. The point being that except for heavy water reactors 
(where they save the water), eventually a fair amount of tritium is 
generated and disposed of.   Not that this is a threat to health and 
safety (after all the preferred cure is to drink lots of good beer), but 
it isn't restricted to BWRs. 

BTW, I never seriously looked at the BWR tritium "economy."   Anybody else 
want to weigh in on this?

 - - jmr

John Rich
312-269-3768

From:
"Brennan, Mike  (DOH)" <Mike.Brennan at DOH.WA.GOV>
To:
<radsafe at radlab.nl>
Date:
02/02/2010 11:01 AM
Subject:
RE: [ RadSafe ] Vermont Yankee leaking tritium --- time to panic(?)

I admit to being prejudiced by my Navy experience in favor of PWRs, but tritium leaking into the environment is one of the reasons I don't care for BWRs.  When you move coolant all over the place, it is a lot easier for some to get away. 

-----Original Message-----
From: radsafe-bounces at radlab.nl [mailto:radsafe-bounces at radlab.nl] On Behalf Of Steven Dapra
Sent: Monday, February 01, 2010 5:31 PM
To: radsafe at radlab.nl
Subject: [ RadSafe ] Vermont Yankee leaking tritium --- time to panic(?)

Feb. 1

http://news.yahoo.com/s/ap/20100201/ap_on_bi_ge/us_leaking_nuclear_plant
s

Steven Dapra

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