Next-generation nuclear reactors may not be safer: French watchdog

[kristopher]

14. You are quite the character

IRSN's presser:

On the basis of its examination, IRSN considers the SFR system to be the only one of the various nuclear systems considered by GIF to have reached a degree of maturity compatible with the construction of a Generation IV reactor prototype during the first half of the 21st century; such a realization, however, requires the completion of studies and technological developments mostly already identified.

The main advantage of SFR technology in terms of safety is the use of low-pressure liquid coolant. The normal operating temperature of this coolant is significantly lower than its boiling point (margin of about 300°C), allowing a grace period of several hours during loss-of-cooling events. The advantage gained from the high boiling point of sodium, however, must be weighed against the fact that the structural integrity of the reactor cannot be guaranteed near this temperature.

The use of sodium also comes with a number of drawbacks due to its high reactivity with water and air. While it seems possible for SFR technology to guarantee a safety level at least equivalent to that targeted generation III pressurised-water reactors, IRSN is unable to determine whether it could significantly exceed this level....

...The feasibility of the system, however, has yet to be determined; it will chiefly depend on the development of fuels and materials capable of withstanding high temperatures, the currently considered operating temperature of around 1000°C being close to the transformation temperature of materials commonly used in the nuclear industry.

...No operating experience feedback from the other four systems studied can be put to direct use. The technological difficulties involved rule out any industrial deployment of these systems within the time frame considered.

...At the present stage of development, IRSN does not notice evidence that leads to conclude that the systems under review are likely to offer a significantly improved level of safety compared with Generation III reactors, except perhaps for the VHTR, whose feasibility is however not acquired.

http://www.irsn.fr/EN/newsroom/News/Pages/20150427_Generation-IV-nuclear-energy-systems-safety-potential-overview.aspx

If you have specific quotes from the report that contradict their press release or my reading of it, then post those quotes.

To get you started, here is the conclusion from the preface of the report.

Conclusion

IRSN draws attention to the fact that the review of the Generation IV nuclear systems selected by GIF primarily focused on their intrinsic qualities in order to determine their “safety potential”. The safety of these facilities will ultimately depend on the design and operating provisions implemented. Whatever the case, the assessments made will have to be reviewed once the systems have made further progress and new knowledge has been acquired. This is particularly true if the deployment of Generation IV reactors is delayed and postponed until the end of the century. Similarly, current assessments of these systems could be reconsidered due to the emergence of new, more realistic nuclear power scenarios that take into account industrial conditions and make allowance for the decommissioning of present and future reactors. A well-balanced safety and radiation protection assessment of these systems is impossible at present owing to deployment time frames, which can be very different, significant gaps in degrees of maturity, and the fact that the state of knowledge varies considerably according to the system. Consequently, the indications given in the IRSN report should be viewed with caution.

At the present stage of development, IRSN does not have all the necessary data to determine whether the systems under review are likely to offer a significantly improved level of safety compared with Generation III reactors, except perhaps for the VHTR, which is a low-power reactor. For this reason, the VHTR does not seem compatible with the objective - if confirmed - of renewing the existing nuclear power reactor fleet and, in any case,could not be constructed in the short term given the temperatures involved.

Much more research is still required to corroborate this general standpoint. For example, few studies are available on the behaviour of these systems under severe accident conditions.

IRSN also stresses that the Generation IV systems selected by GIF are intended for different national conditions. The selected systems can be associated with different fuel management modes (e.g. open or closed cycles, plutonium breeding or burning) and are therefore not all suited to the energy context in France. Some criteria such as sustainable and optimised management of natural resources and waste, which are particularly associated with fast reactors, are not necessarily compatible with a significant improvement in reactor safety. This is largely because of high operating temperatures and the toxicity and corrosive nature of most coolants considered.

Regarding SFRs, and possibly GFRs and LFRs, IRSN restates its position on research into minor actinide transmutation, namely that this option offers only a very slight advantage in terms of inventory reduction and geological waste repository footprint when set against the induced safety and radiation protection constraints for fuel cycle facilities, reactors and transport. On this point, ASN has recently announced that minor actinide transmutation would not be a deciding factor in the choice of a future reactor system.

Lastly, it should be borne in mind that any industrial deployment of a Generation IV reactor system in France will be linked to its advantages, not only regarding reactor fleet operation and safety, but also in terms of the coherence and performance of the associated fuel cycle. This concerns all aspects relating to safety, radiation protection, material management and efforts made to minimise the quantities of radioactive waste generated, without overlooking the overall economic competitiveness of the nuclear system. Ultimately, the choice of system must be made as part of an integrated approach, based on studies that cover multiple criteria and all the aspects mentioned above.

The discussion has both generic and Franco-centric elements.

http://www.irsn.fr/EN/newsroom/News/Documents/IRSN_Report-GenIV_04-2015.pdf