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:
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 defined by: ES(t) = (f Y+P)S HY+P(t) + fI HI(t) Where (f +)S = fraction of total solid fission product energy absorbed in coolant outside core HY+P(t) = total solid fission product energy production rate, ev/sec-MWt fI = fraction of iodine isotope energy absorbed in coolant outside core HI(t) = iodine isotope energy production rate, ev/sec-MWt. The equations for oxygen generation by radiolysis are identical to those above describing hydrogen evolution except that the yield is one-half that of hydro- gen. These equations have been incorporated into the COGAP program. For cal- culational purposes, the reactor decay profiles (H (t) H (t), and H1(t)) specified by the ANS-5.1 draft standard for two-yeXr reactoO operation have been fitted by several finite exponential series expressions and also incorporated into the program. The resulting equations are: H Y(t) = 1022(5.1912e 9 8 x 10t + 0.8743e -6.5 x 10 6t -57x1-7 74x108 -8 .0x1-10) + 0.6557e 7 t + .4098e 7-4 x l0t + .0150e 8 0 x 10 t) H Y+P(t) = 2.0 HY(t) HI2(t) = lZ(O.8l97e U-6 x 10 t + 3279e-11 x 105t + .0574e 1 0 X 10 6 t) where t = time after reactor shutdown, sec. Between 400 and 4 x 107 sec, the equations overpredict the standard curve by 20%. The equations underpredict the standard curve soon after shutdown. However, this does not seriously affect the results due to the short time period involved. The equations are equivalent to the afterheat decay curve in BTP ASB 9-2 over the times of interest for post-accident hydrogen generation. It should also be noted that the COGAP formulation overpredicts the radiolytic hydrogen generation by a small amount due to a "double-counting" of the gamma energy of those fission products assumed to be released from the fuel rods. Hydrogen generation due to aluminimum corrosion is