ML16340A068
| ML16340A068 | |
| Person / Time | |
|---|---|
| Site: | Rhode Island Atomic Energy Commission |
| Issue date: | 02/04/2010 |
| From: | Edward Helvenston NRC/NRR/DPR/PRLB |
| To: | |
| Helvenston E | |
| References | |
| Download: ML16340A068 (2) | |
Text
RI Atomic Energy Commission Safety Analysis Report RI Nuclear Science Center Appendix A 1
2 3
4 5
6 7
21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 Nitrogen-16 The Nitrogen-16 activity acquired by the coolant depends upon the flow pattern of the coolant and its residence times within and without the neutron flux. The figure shows a simplified coolant flow loop. The residence time within the neutron flux is denoted as ti. The residence time without the neutron flux is dominated by the stay time in the delay tank and is denoted td.
8 9
10 11 12 13 14 15 16 17 18 19 20 Reactor Core Heat Exchanger Delay Tank ti td Consider a unit volume of water leaving the reactor. If its Nitrogen-16 activity at this point is,
then at time td later, when it re-enters the reactor, its activity will have decayed to e-t where is the radionuclides decay constant and t is equal to td.
In passing through the reactor, the Nitrogen-16 continues to decay, (i.e. e-t) where is the radionuclides decay constant and t is equal to ti.
In the reactor, the unit volume is exposed to an average flux av and acquires in the time ti the additional activity act av(1-e-t), where act is the average macroscopic activation cross section in the flux av. If T is the total of ti and td, the total activity leaving the reactor is e-T+ act av(1-e-t).
At equilibrium, after the coolant has made many passes around the circuit, the total activity is equal to or = e-T+ act av(1-e-t).
Argon-41 Argon-41 is produced by activation of natural argon (a normal trace element in atmospheric air). Argon-41 decays to Potassium-41 with a half-life of 100 minutes (0.076 days) by the emission of a 1.2-MeV beta particle and a 1.3-MeV gamma ray.
Argon-41 production is dependent upon the dissolved air in the reactor coolant. Since the amount of dissolved air in the coolant is variable depending upon the air influx from the various beam tubes, empirical data was selected over calculations. We used historic Argon-41 release rates and the Comply Code to determine off-site dose equivalents associated with its release.
Revision 0
-1 2/4/10
RI Atomic Energy Commission Safety Analysis Report RI Nuclear Science Center Revision 0
-2 2/4/10 1
Argon-41 Releases - 1997-2002 0
5 10 15 20 25 30 35 40 January March May July September November January March May July September November January March May July September November January March May July September November January March May July September November January March May July Month Curies 2
3 Estimated Offsite Argon-41 Dose Equivalents - 1997-2002 0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 January March May July September November January March May July September November January March May July September November January March May July September November January March May July September November January March May July Month mrem 4