| Thanks for the response. I had previously gone though the Oklo COLA, which is indeed hundreds of pages. But quantity is not always quality. I have seen the same types of submissions from other reactor proponents, and they are far more detailed, comprehensive, and informative and they are mostly at earlier stages of NRC engagement in pre-application discussions. As an example, I can't find a basic dimensioned or labeled reactor drawing or system diagram in Oklo's COLA. As far as the COLA illustrates, the Aurora design consists of an A-Frame drawing and a cylindrical vessel in a dugout. The safety analysis provided are generally simplified, rarely showing uncertainties or limitations of the analysis. See the NuScale or GE-Hitachi designs in pre-application or even the Transformational Challenge Reactor (TCR) as an example of a well documented research thrust that has not even begun the regulatory process if it ever will: https://tcr.ornl.gov/publications/ As far as spent fuel goes, the EBR II fuel that Oklo plans to use took decades to reprocess at a cost much greater than 0, which Oklo is not paying for. EBR II is not a civilian power generating reactor like all LWRs and BWRs currently in operation. Perhaps one day, reprocessing spent fuel will be cost effective. But today, it is a totally unnecessary activity as there's plenty of uranium and spent fuel storage is not an issue. I think telling congress that Aurora will consume spent fuel from today's reactors is false and disingenuous, both because it is extremely expensive to do so and because it is not particularly useful. Aurora is ostensibly a tiny fast reactor, though I have to guess at this as there are no dimensioned figures in the COLA. Neutron leakage is going to be big and burnup low. This might be why Aurora is limited to 1% burnup. Maybe Oklo plans to make much larger reactors in the future, which have very different safety characteristics but can achieve higher burnup. It's curious that of the 70+ reactors in development, there are no fast spectrum and tiny reactors except for Oklo. There are fast reactors like TerraPower Natrium but they 200x larger than Aurora. The calculation for tons / GWe-yr is as below assuming a 33% efficient power cycle (reasonable given the low temperatures of the heat pipes, but maybe the sCO2 is really good). GWe-yr is a unit of energy. 1.5 MWe * 20 yr means you are producing 4.5 MWth for 20 years, and must have fissioned 35 kg of Uranium (you get 200 MeV per U fission which is 2.6 MWyr / kg U). If 1% burnup is assumed, as indicated, Aurora is using 3500 kg or 3.5 tons of HALEU. I think this would change a bit depending on the spectrum. 3 tons HALEU / (1.5 MWe * 20 yr) * (1000 MW / 1 GW) = 100 ton HALUE / GWe-yr |
- you don't see these detailed core schematics with analyses because in our design they are designated export controlled (ECI) as I mentioned. It doesn't mean that they aren't in there or that they haven't been extensively performed and documented.
- the endeavor (and cost) of downblending EBR-II fuel over many years has been based on the national and state nonproliferation agreements to downblend this high enriched used fuel from EBR-II. Don't confuse that endeavor with processing used, low-enriched fuel from existing plants. In the one case, the downblending work was being performed for many years in the interest of downblending before storing as waste (except now, instead, it can be used to produce clean power and demonstrate a FOAK fission plant). In the other case, recycling existing waste, we are already working with DOE (and starting NRC interactions) about deploying recycling existing nuclear waste for fuel. I can tell you it's incredibly cost effective for a fast reactor to utilize the TRU in existing low-enriched waste and that is our goal for not just feel-good reasons but also for economic reasons. It is not false nor disingenuous.
It's true that the burnup is far less than would be ultimately most economically efficient. The FOAK was intended to serve as a bit of an MVP as I already mentioned. But it's key that larger doesn't mean less safety. The fundamentals of the safety in this case lie in how the fuel has inherent shutdown characteristics, which were proven true of EBR-II (at 65 MWth) even as it's true of Aurora (<10MWth). Many different plants have different mechanisms of safety at various size ranges!
Thanks for engaging and your thoughtful responses.