3 ms·

The pool is for passive secondary cooling if the primary fails. It is outside the containment and is intended to boil off over 30 days if there is a complete b

by baking 7y ago

The pool is for passive secondary cooling if the primary fails. It is outside the containment and is intended to boil off over 30 days if there is a complete blackout. 30 days is all you need for the decay heat because after that air cooling is sufficient.

Animats 7y ago
Not 30 days. 72 hours. "Water inventory in the reactor pool is adequate to cool the NPMs for at least 72 hours without adding water." NRC filing [1], page 41, bottom of page. A NuScale press release does say that. "The system is capable of providing 30 days of cooling without adding water to the pool."[2] The web site hype goes even further: "Should it become necessary, NuScale’s SMR shuts itself down and self-cools for an indefinite period of time, with no operator action required, no additional water, and no AC or DC power needed."[3] But that's not what the NRC filing says. Looks like they make bigger claims when they think they can get away with it. [1] https://www.nrc.gov/docs/ML1924/ML19241A398.pdf https://www.nrc.gov/docs/ML1924/ML19241A398.pdf [2] https://newsroom.nuscalepower.com/sites/nuscalepower.newshq.businesswire.com/files/doc_library/file/nuclear-exchange-sept-2011.pdf https://newsroom.nuscalepower.com/sites/nuscalepower.newshq.... [3] https://www.nuscalepower.com/ https://www.nuscalepower.com/
- baking 7y ago
  That accusation seems a little extreme. The 30 day claim was published in January 2012 in response to the Fukushima accident: https://www.tandfonline.com/doi/abs/10.13182/NT12-A13556 https://www.tandfonline.com/doi/abs/10.13182/NT12-A13556 Also, in "NuScale Technical Report Long-Term Cooling Methodology, dated January 2017, TR-0916-51299" (https://www.nrc.gov/docs/ML1835/ML18355A973.pdf https://www.nrc.gov/docs/ML1835/ML18355A973.pdf) "5.3.4 Long Term Cooling Evaluation Period LTC analysis is limited to three days. This timeframe is considered acceptable because: (1) the most severe conditions will have been captured within the 72 hour window analyzed, and any conditions that could reasonably be expected to occur beyond this time period are thus bounded by the 72 hour calculation, and (2) after 72 hours, operator actions can be credited. When realistic initial operating levels, temperatures, and decay heat are considered, the scope of the LTC analyses bound the expected level decrease in the reactor pool ultimate heat sink over 30 days, for up to twelve modules transferring decay and residual heat to the reactor pool." I read this as that they ran a number of scenarios with extreme initial conditions and at the end of three days all operating characteristics were effectively the same as with typical starting conditions and therefore they expected the 30 day simulations would give the same result no matter what the initial conditions were. I don't think they are hiding anything here.
  - Animats 7y ago
    That's so heavily censored it's hard to tell anything from it.

by baking 7y ago

Animats 7y ago

Not 30 days. 72 hours. "Water inventory in the reactor pool is adequate to cool the NPMs for at least 72 hours without adding water." NRC filing [1], page 41, bottom of page. A NuScale press release does say that. "The system is capable of providing 30 days of cooling without adding water to the pool."[2] The web site hype goes even further: "Should it become necessary, NuScale’s SMR shuts itself down and self-cools for an indefinite period of time, with no operator action required, no additional water, and no AC or DC power needed."[3] But that's not what the NRC filing says. Looks like they make bigger claims when they think they can get away with it. [1] https://www.nrc.gov/docs/ML1924/ML19241A398.pdf https://www.nrc.gov/docs/ML1924/ML19241A398.pdf [2] https://newsroom.nuscalepower.com/sites/nuscalepower.newshq.businesswire.com/files/doc_library/file/nuclear-exchange-sept-2011.pdf https://newsroom.nuscalepower.com/sites/nuscalepower.newshq.... [3] https://www.nuscalepower.com/ https://www.nuscalepower.com/

baking 7y ago
That accusation seems a little extreme. The 30 day claim was published in January 2012 in response to the Fukushima accident: https://www.tandfonline.com/doi/abs/10.13182/NT12-A13556 https://www.tandfonline.com/doi/abs/10.13182/NT12-A13556 Also, in "NuScale Technical Report Long-Term Cooling Methodology, dated January 2017, TR-0916-51299" (https://www.nrc.gov/docs/ML1835/ML18355A973.pdf https://www.nrc.gov/docs/ML1835/ML18355A973.pdf) "5.3.4 Long Term Cooling Evaluation Period LTC analysis is limited to three days. This timeframe is considered acceptable because: (1) the most severe conditions will have been captured within the 72 hour window analyzed, and any conditions that could reasonably be expected to occur beyond this time period are thus bounded by the 72 hour calculation, and (2) after 72 hours, operator actions can be credited. When realistic initial operating levels, temperatures, and decay heat are considered, the scope of the LTC analyses bound the expected level decrease in the reactor pool ultimate heat sink over 30 days, for up to twelve modules transferring decay and residual heat to the reactor pool." I read this as that they ran a number of scenarios with extreme initial conditions and at the end of three days all operating characteristics were effectively the same as with typical starting conditions and therefore they expected the 30 day simulations would give the same result no matter what the initial conditions were. I don't think they are hiding anything here.
- Animats 7y ago
  That's so heavily censored it's hard to tell anything from it.