Method for preparing spent nuclear fuel for dry storage

1. A method of preparing spent nuclear fuel for dry storage drying comprising:

a) flowing a non-reactive gas through a cavity containing spent nuclear fuel;

b) repetitively measuring dew point temperature of the non-reactive gas exiting the cavity;

c) upon the dew point temperature of the non-reactive gas exiting the cavity being measured to be at or below a predetermined dew point temperature, activating a timer;

d) running the timer for a predetermined period of time to ensure a dryness level of the cavity;

e) discontinuing the flow of the non-reactive gas after lapse of the timer; and

f) sealing the cavity.

2. The method according to claim 1 , wherein step (a) comprises flowing the non-reactive gas through the cavity containing the spent nuclear fuel at a predetermined flow rate.

3. The method according to claim 2 , wherein the predetermined time is based on the predetermined flow rate and volume of the cavity.

4. The method according to claim 3 , wherein the predetermined flow rate is chosen so that the volume of the cavity is turned over 25 to 50 times per hour.

5. The method according to claim 1 , wherein the predetermined dew point temperature is selected to correspond to a desired vapor pressure within the cavity.

6. The method according to claim 1 , wherein the predetermined dew point temperature is in a range of approximately 20 to 26° F., and the predetermined time is in a range of approximately 25 to 35 minutes.

7. The method according to claim 6 , wherein the predetermined dew point temperature is approximately 22.9° F. and the predetermined time is approximately 30 minutes.

8. The method according to claim 1 , wherein after step b) drying the non-reactive gas with a chiller.

9. The method according to claim 1 , wherein the non-reactive gas is nitrogen, carbon dioxide, light hydrocarbon gases, or a noble gas selected from the group consisting of helium, argon, neon, radon, krypton, and xenon.

10. The method according to claim 9 , wherein the non-reactive gas is helium.

11. The method according to claim 1 , wherein the predetermined dew-point temperature is selected to correspond to a vapor pressure of 3 Torr or less in the cavity.

12. The method according to claim 1 , further comprising drying the non-reactive gas that exits the cavity with a drying apparatus after step b).

13. The method according to claim 12 , further comprising re-circulating the dried non-reactive gas back through the cavity after drying the non-reactive gas in a closed flow loop.

14. A method of preparing spent nuclear fuel for dry storage drying comprising:

a) flowing a non-reactive gas through a cavity containing spent nuclear fuel;

b) repetitively measuring dew point temperature of the non-reactive gas exiting the cavity;

c) drying the non-reactive gas that exits the cavity with a moisture removal apparatus after the dew point temperature is measured;

d) re-circulating the dried non-reactive gas back through the cavity after drying the non-reactive gas in a closed flow loop;

e) upon the dew point temperature of the non-reactive gas exiting the cavity being measured to be at or below a predetermined dew point temperature, activating a timer;

f) running the timer for a predetermined period of time to ensure a dryness level of the cavity;

g) discontinuing the flow of the non-reactive gas; and

h) sealing the cavity.

15. The method according to claim 14 , wherein the moisture removal apparatus is a chiller.

16. The method according to claim 14 , wherein step d) is performed using a recirculation pump downstream of the moisture removal apparatus in the closed flow loop.

17. The method according to claim 16 , further comprising a gas reservoir fluidly coupled in a serial flow arrangement in the closed flow loop downstream of the recirculation pump, wherein the recirculation pump forcible flows the non-reactive gas through the gas reservoir.

18. The method according to claim 17 , further comprising a gas supply pump fluidly coupled in a serial flow arrangement in the close flow loop downstream of the gas reservoir, wherein activating the gas supply pump and the recirculation pump results in the non-reactive gas being drawn from the helium reservoir and flowed through the closed-loop fluid.

19. The method according to claim 17 , further comprising a flow rate valve arranged in the closed flow loop between the gas reservoir and the cavity, the flow rate valve configured and operable to control a flow rate of the non-reactive gas circulating through the closed flow loop, and wherein the predetermined time is based on a predetermined flow rate and volume of the cavity.

20. A method of preparing spent nuclear fuel for dry storage drying comprising:

a) flowing a non-reactive gas through a cavity containing spent nuclear fuel;

b) repetitively measuring dew point temperature of the non-reactive gas exiting the cavity;

c) drying the non-reactive gas that exits the cavity after the dew point temperature is measured;

d) re-circulating the dried non-reactive gas back through the cavity after drying the non-reactive gas in a closed flow loop; and

e) upon the dew point temperature of the non-reactive gas exiting the cavity being measured to be at or below a predetermined dew point temperature, running a timer for a predetermined period of time to ensure a dryness level of the cavity.