Document: NUREG-0800
Document ID: 936f16a2-5593-4498-8533-ddca55910376
Document Type: srp
Title: COMBUSTIBLE GAS CONTROL IN CONTAINMENT
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0523/ML052340704.pdf
Revision Date: 2023-06
Chapter: 6
Section ID: 6.2.5
CFR Part: 
CFR Title: 

Content:
nts, with the oxygen generated following a LOCA. The extent of zirconium-water reaction and associated hydrogen production depends strongly upon the course of events assumed for the accident. Analyti- cally the reaction can be described by: Zr + 2H20 T ZrO2 + 2H2 1 lb Zr - 0.043956 lb H2 1 lb Zr - 0.021978 lb-mole H2. Therefore, one pound of reacted zirconium will produce 0.021978 pound-moles of free hydrogen. Assuming the perfect gas relationship, this is equivalent to 8.4866 scf/lb Zr: v = MRT V = 0.021978(10.71)(530) V = 8.4866 scf/lb Zr. 6.2.5-11 Rev. 2 - July 1981 The total amount of hydrogen produced is based on the amount of reacted zircon- ium, as determined by the assumptions given in Branch Technical Position CSB 6-2. The computer program, to maintain a degree of generality, allows the reaction percentage to be specified as an input quantity. The expression used is: WG = (.022)(WZr)(fO) where WG = pound moles of hydrogen generated WZr = weight of zirconium fuel element clad fMW = zirconium-water reaction fraction. The rate of gas production from radiolysis depends upon the power decay profile and the amount of fission products released to the coolant. The radiolytic hydrogen production rate at time (t) is given by: p GCEC (t) + GSESMt SH(t) = TG E 0 t where SH(t) = hydrogen production rate, lb-mole/sec P = operating reactor power level, MWt B = conversion factor, 454 gm-mole/lb-mole N = Avogadro's number, 6;023 x 1023 molecules/gm-mole Gc = radiolytic hydrogen yield in core, molecules/100 ev Ec(t) = gamma ray fission product energy absorbed by core coolant, ev/sec-MWt G = radiolytic hydrogen yield in solution, molecules E5(t) = energy absorbed in coolant outside core due to fission products dissolved in coolant, ev/sec-MWt. quantity E C(t) is defined by: E c) = fq)c Hq() The c where (fy)c = HY(t) = fraction of fission product gamma energy absorbed by coolant in core region gamma energy production rate, e 6.2.5-12 Rev. 2 - July 1981 Similarly, Es(t) is