NANTeL Chemistry and Water Treatment 3

Question 1

What does elevated specific activity in reactor coolant most likely indicate to a plant chemist?

Accepted Answer

Possible fuel cladding defects allowing fission products into the coolant

Answer

High specific activity in reactor coolant indicates fission products may be leaking through defective fuel cladding into the coolant, which is monitored as a key fuel integrity indicator under 10 CFR 50 Appendix A.

Question 2

Why is iodine-131 (I-131) concentration in reactor coolant a particularly important chemistry surveillance parameter?

Accepted Answer

Elevated I-131 strongly indicates fuel cladding failure since it is a fission product

Answer

I-131 is produced exclusively by fission inside fuel; its presence in coolant above tramp uranium background levels indicates fuel cladding breaches allowing fission gases to enter the primary system.

Question 3

Which instrument type is most commonly used for continuous monitoring of dissolved oxygen in nuclear plant feedwater and coolant systems?

Accepted Answer

Electrochemical cell or optical luminescence dissolved oxygen analyzer

Answer

Electrochemical (polarographic/galvanic) cells and optical luminescence sensors provide continuous, accurate dissolved oxygen readings at the ppb levels critical for nuclear plant corrosion control programs.

Question 4

What information does an E-pH (Pourbaix) diagram provide that is useful to nuclear plant chemists?

Accepted Answer

Thermodynamic stability regions of metals and corrosion products as functions of potential and pH

Answer

Pourbaix diagrams map the thermodynamic stability of metals and their oxides/hydroxides versus electrochemical potential and pH, helping chemists select operating conditions that keep structural materials in their passive or immune regions.

Question 5

What is the primary purpose of depleted zinc oxide (DZO) injection in a nuclear plant chemistry program?

Accepted Answer

To incorporate zinc into oxide films and displace cobalt-60, reducing radiation fields

Answer

Zinc incorporates into the oxide films on reactor coolant system surfaces and displaces radioactive cobalt-60 (from cobalt-59 activation), reducing out-of-core radiation fields and occupational dose.

(NANTeL) National Academy for Nuclear Training e-Learning Practice Test

(NANTeL) National Academy for Nuclear Training e-Learning Practice Test

NANTeL Chemistry and Water Treatment 3