Chemistry Control - .5

Question 1

Why do we have chemistry operational limits?

Answer 1

Operation outside of these limits will increase corrosion rates that could cause equipment damage/failure

Question 2

How do BWR’s maintain the highest purity water possible?

Answer 2

1. Rely on filtration and demineralization via RWCU and CPS.
2. By controlling purity, we control the amount of free ions in the reactor water thereby providing some control over corrosion rates.

Question 3

What are the chemistry requirements in various opcons?

Answer 3

OpCon Cl- L pH
1 ≤ .2 ppm ≤ 1 5.6 ≤ pH ≤ 8.6
2/3 ≤ .1 ppm ≤ 2 5.6 ≤ pH ≤ 8.6
4/5 ≤ .5 ppm ≤ 10 5.3 ≤ pH ≤ 8.6

Question 4

What are the requirements regarding Dose Equivalent Iodine and why?

Answer 4

Iodine (<.2 uCi/g) – That concentration of I-131 which alone would produce the same thyroid dose as the quantity of isotopic mixture of I-131 thru 135 present in the coolant. (Ensures the resulting two hour thyroid doses at the site boundary will not eceed a small fraction of the 10CFR100 limits following a MSL failure outside of the containment during steady state conditions.

Question 5

What are the requirements for Gross beta/Gamma and why?

Answer 5

(100/E Bar uCi/g) – Weighted average of the sum of the average beta and gamma energies (in Mev) for isotopes, other than iodines, with half-lives gerater than 15 minutes, making up at least 95% of the total non-iodine activity in the coolant. Ensures the 2 hour thyroid and WB doeses resulting from a MSL failure outside of the containment during steady state ops will not exceed small fractions of the 10CFR100 limits.
See Primary Containment Notes for 10CFR100 Thyroid and WB dose limits.