FGR-13 and H-3

["Pilt, Aadu" <Aadu.Pilt@jus.gov.on.ca>]

Radsafers:

There has been much discussion of the "evils" of FGR-13 and how it
purports to give risk coefficients "per Bq ingested/inhaled/exposed".

Well, I'm not convinced that this is any different from the approach
taken by the IAEA etc. in the Basic Safety Standards.

In fact, I find the two documents (at least for ingested tritium in
water) to be identical.

I take the Ontario Drinking Water Objective of 7000 Bq/L as a starting
point. (The actual concentration of tritium in water is of the order of
10 Bq/L; the highest observed in Ontario recently has been 1500 Bq/L for
a day or two following an accidental discharge to Lake Ontario.

7000 Bq/L at 2 L/day for 1 year is 5.0E+06 Bq/y.

The BSS suggest a DCF of 2.0E-11 Sv/Bq; thus one year's consumption is
0.1mSv (and that is of course where the 7000 Bq/L came from in the first
place).

Taking an IAEA risk coefficient of 5.0E-02/Sv, we get a yearly risk of
5.0E-06.

Now we go to your FGR-13.

This gives a mortality risk coefficient for tritium of 9.44E-13/Bq --
call it 1.0E-12/Bq.

Multiplying this by the 5.0E+06 Bq/y we get (ta-da!!) a risk of 5.0E-06
per year.

So I conclude that all FGR-13 does is multiply the IAEA dose conversion
factors by the IAEA risk coefficient (for all intents and purposes). We
do this all the time anyway. What's the big deal?

Dr A A Pilt
Emergency Measures Ontario

aadu.pilt@jus.gov.on.ca