Question

Show all work so I can better understand how to master this topic. I included the constants page, but you may or may not need them. Problem 9 During refueling of a PWR, a control valve for the CVCS (chemical and volume control system) fails to close and a large amount of boric acid (B(OH3), a neutron poison, is released into the primary coolant loop. Fortunately, the reactor operators recognize the issue before restarting and dilute the solution by cycling in pure water. (a) List two other neutron poisons and their sources. b After the chemical shim emptied its contents into the primary coolant loop, the boric acid concentration was 9100 ppm in the reactor's 250m3 coolant system. If the pumps have a volumetric flow rate of 10m3/min, how much time would it take to reduce the concentration down to 3500 ppm? For the sake of this question, ppm is in terms of mass rather than atoms. (c) The reactor operators decide to remove the remaining excess boric acid by burning it away during normal operation. If the only reaction mechanism involving boric acid is its absorption of neutrons, how long would it take to reduce the concentration down to 2500 ppm? Boron-10 absorption cross section is 3840 b. Neutron flux is 1015 n/cmsec. Coolant density is 1.0 g/mL No boric acid is being added during this time. (d) Explain why coolant water used in primary coolant loops must be ultra-pure Conversion that may come in handy: 1 eV=1.60210-19 J 1 amu=931.49MeV N=6.0221023atoms/mol 1tonne=1000 kg 1 Ci=3.7101Bq 1Gy=100rad 1Sv=100 rem Recoverable energy from 1 fission process:190MeV NRC occupational exposure limit:5 rem/y. Potentially useful atomic masses Isotope Atomic mass (u) Proton 1.007276466879 Neutron 1.00866491585 H-1 1.00782503223 H-2 2.01410177812 He-4 4.00260325413 O-16 15.99491461957 U-235 235.043930131 U-238 238.050788423 Radiation Quality Factors Type of Radlation QF X-rays, gamma rays 1 beta particles 1 alpha particles 20 thermal neutrons ( 1 keV) 2 fast neutrons (I MeV 11

Show all work so I can better understand how to master this topic. I included the constants page, but you may or may not need them.
Problem 9
During refueling of a PWR, a control valve for the CVCS (chemical and volume control system) fails to close and a large amount of boric acid (B(OH3), a neutron poison, is released into the primary coolant loop. Fortunately, the reactor operators recognize the issue before restarting and dilute the solution by cycling in pure water.
(a) List two other neutron poisons and their sources.
b After the chemical shim emptied its contents into the primary coolant loop, the boric acid concentration was 9100 ppm in the reactor's 250m3 coolant system. If the pumps have a volumetric flow rate of 10m3/min, how much time would it take to reduce the concentration down to 3500 ppm?
For the sake of this question, ppm is in terms of mass rather than atoms.
(c) The reactor operators decide to remove the remaining excess boric acid by burning it away during normal operation. If the only reaction mechanism involving boric acid is its absorption of neutrons, how long would it take to reduce the concentration down to 2500 ppm?
Boron-10 absorption cross section is 3840 b. Neutron flux is 1015 n/cmsec. Coolant density is 1.0 g/mL No boric acid is being added during this time.
(d) Explain why coolant water used in primary coolant loops must be ultra-pure
Conversion that may come in handy: 1 eV=1.60210-19 J 1 amu=931.49MeV N=6.0221023atoms/mol 1tonne=1000 kg 1 Ci=3.7101Bq 1Gy=100rad 1Sv=100 rem Recoverable energy from 1 fission process:190MeV NRC occupational exposure limit:5 rem/y.
Potentially useful atomic masses
Isotope Atomic mass (u) Proton 1.007276466879 Neutron 1.00866491585
H-1 1.00782503223 H-2 2.01410177812 He-4 4.00260325413 O-16 15.99491461957
U-235 235.043930131 U-238 238.050788423
Radiation Quality Factors
Type of Radlation QF
X-rays, gamma rays 1 beta particles 1
alpha particles 20 thermal neutrons ( 1 keV) 2 fast neutrons (I MeV 11

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