Saturday, June 4, 2011

Could Small Be Beautiful?

When I was compiling my list of reactors being marketed as of early 2011, I ignored a number of small designs that I felt were unlikely to be built.  There are more than a few such proposals, with many of them coming from various state-owned design bureaus in Russia.  During the early days of nuclear power, in the 1950s and 1960s, various national governments put money into building small reactors of interesting designs.  Some of those include Hallam, Piqua, Fort St. Vrain, Niederaichbach, Jülich, and the Steam-Generating Heavy Water Reactor.  None of these worked well enough to be cost-effective, and the nuclear power industry has come to be dominated by large light water reactors.

More recently, governments have been supporting research and development of small reactors, but only two examples of one model from Russia have been built.  Some private corporations are also working on new reactor designs with their own funds, but none have completed licensing.  Generically, these new designs are called SMRs, which stands either for small modular reactors or, less often, small and medium reactors.  The International Atomic Energy Agency defines small reactors as less than 300 MWe, and medium reactors as 300-700 MWe.  The word modular refers to how proponents see these reactors as being deployed, which would be at power plants with 4 to 20 units.

The main appeal of these reactors is the capital cost of any one of them.  Large nuclear reactors have a long history of enormous cost overruns on the initial estimates, which are also enormous.  The 1600 MWe European Pressurized Reactor (EPR) currently being built at Olkiluoto in Finland was sold as a turnkey contract for €3.3B, but cost overruns have pushed the price to over €6B - so far.  SMR proponents are projecting costs of their reactors from $50M to $1B, depending on the design.  But almost all of the designs haven't reached the final detailed design stage, so it is possible (and quite likely) that the estimates could turn out to be as wrong as ones for large reactors.  However, even if the estimates are wrong, the smaller reactors would be less risky for utilities to build because an overrun with any one reactor wouldn't threaten to bankrupt the company.

According to proponents, there are several other positive aspects to SMRs, though they don't all have the same ones.  For most, the smaller size would allow large sections to be mass manufactured off-site in controlled factory conditions, with only final assembly done on site.  This has the potential (in theory) to improve quality assurance over large reactors, which are largely custom built on-site of essentially one-off parts.  Some designs are small enough that they would be delivered as pre-fueled packages and then sent back to the factor when the fuel is exhausted.  That could significantly reduce the amount of waste generated at the power plant site, eliminate complicated on-site refueling operations, and potentially reduce the chances of fuel theft or proliferation.  It would not eliminate the chance of accidents or theft during transit, however, though the latter would be difficult.  Most of the designs call for the reactors to be housed underground, which basically eliminates the chance of damage from missiles or airplanes.  However, the crisis at Fukushima Dai-ichi has shown that backup systems can be critical.  Some of the new designs still require active cooling by a backup system after shutdown, and most leave these systems exposed.  Finally, depending on the size, some of the new reactors could be deployed in rural or remote locations where only a moderate amount of power is needed and a large reactor would overwhelm the local grid.

The main question about these designs is whether or not they would, when deployed en mass, end up being safer.  Clearly, if there was an accident with any one reactor, it would make less of a mess than a larger reactor would.  But I doubt whether 1000 reactors each of 100 MWe would be monitored and inspected as carefully as a set of 100 reactors of 1000 MWe.  That means each small reactor deployed has to have a radically lower probability of having its containment breached to make up for poorer monitoring and greater numbers.  Some of the designs may actually be that much safer, but until a plant goes through a rigorous licensing process, we have no way of knowing how good any of them are.

Most of the reactors listed below were pulled from two documents from the IAEA (1, 2), with others coming from Wikipedia or general web surfing.  Because there are so many of them, I may have missed a few.  I've classified some reactors as "abandoned" in the status field if I was unable to find them on the originating organization's website, though the lack of public information doesn't necessarily mean a project has been ended.  The converse is true as well.

By neutron speed, there are:
By major type, there are:

4SSodium-cooled fast reactor3010JapanToshiba Power SystemsUS pre-licensingfactory
4S-LMRSodium-cooled fast reactor13550JapanCRIEPIconceptfactory
ABV-6Pressurized water reactor6012RussiaOKBMconcepton-site
ACACIAHigh temperature gas-cooled reactor6023NetherlandsNRGabandonedon-site
AFPR-100Light water reactor300100USAPNNLabandonedfactory
AFR-300Sodium-cooled fast reactor800300USAANLconcepton-site
AHTRMolten salt-cooled reactor600300USAORNL / UCBconcepton-site
AHWRheavy water-moderated boiling water reactor260100IndiaNPCILdetailed designon-site
ARC-100Sodium-cooled fast reactor920300USAAdvanced Reactor Conceptsconcepton-site
BGR-300Gas-cooled fast reactor300130RussiaRRC Kurchatovconceptfactory
BMN-170Sodium-cooled fast reactor400170RussiaOKBMabandonedon-site
BN GT-300Sodium-cooled fast reactor730300RussiaIPPEconcepton-site
BRESTLead-cooled fast reactor?300RussiaNIKIETconcepton-site
CAREMLight water reactor10027ArgentinaINVAP / CNEAArgentina pre-licensingon-site
CCRBoiling water reactor900300JapanToshiba Power Systemsabandonedon-site
CHTRLead-buismuth-cooled fast reactor0.10.02IndiaBARCconceptfactory
DRXPressurized water reactor0.750.15JapanJAERIabandonedon-site
ELENA NTEPLight water reactor3.30.07RussiaRRC Kurchatovabandonedfactory
EM2Gas-cooled fast reactor500240USAGeneral Atomicsconceptfactory
ENHSLead-cooled fast reactor12550USALLNL / UCBconceptfactory
FBNRPressurized water reactor13440BrazilFURGSconceptfactory
GT-MHRHigh temperature gas-cooled reactor600287USAGeneral Atomicsconcepton-site
GTHTR-300High temperature gas-cooled reactor600274JapanJAERIabandonedon-site
HTGRHigh temperature gas-cooled reactor220100JapanFirst Atomic Power Industry Groupconcepton-site
HTR-PMHigh temperature gas-cooled reactor380160ChinaCNNCprototype
IRISPressurized water reactor?335USAWestinghouse (Toshiba)US pre-licensingon-site
ISISPressurized water reactor650200ItalyAnsaldo Nucleareabandonedon-site
KALIMERLead-cooled fast reactor392150KoreaKAERIconcepton-site
KAMADOLight water reactor1000300JapanCRIEPIabandonedon-site
KLT-40SPressurized water reactor15035RussiaOKBM/ Atomstroyexportproductionon-site
LSPRLead-cooled fast reactor15053JapanRLNR-TITabandonedfactory
MARSMolten salt-cooled reactor166RussiaRRC Kurchatovabandonedfactory
MARSPressurized water reactor600150ItalyU. of Rome / ENEAabandonedon-site
MASLWRPressurized water reactor15045USANuScaleUS pre-licensingfactory
MBRU-12Sodium-cooled fast reactor4812RussiaOKBMabandonedfactory
MDPSodium-cooled fast reactor840325JapanCRIEPIabandonedon-site
mPowerPressurized water reactor400125USABabcock & WilcoxUS pre-licensingon-site
MRXPressurized water reactor100
MSBWRBoiling water reactor?50USAGE / Purdueabandonedon-site
MSR-FUJIMolten salt reactor450200JapanITHMSIconceptcontinuous
NP-300Pressurized water reactor?300FranceAreva NPabandonedon-site
Package ReactorLight water reactor25?JapanHitachi / Mitsubishiabandonedon-site
PBMRHigh temperature gas-cooled reactor400165South AfricaPBMR (ESKOM)abandoned after starting US pre-licensingon-site
PEACER-300Lead-cooled fast reactor850300KoreaSeoul Nat. U.concepton-site
PFPWR-50Light water reactor50n/aJapanHokkaido U.conceptfactory
Power ModuleLead-bismuth-cooled fast reactor7525USAHyperion Power GenerationUS pre-licensingfactory
PRISMLead-cooled fast reactor840311USAGE-HitachiUS pre-licensingon-site
PSRDLight water reactor10031JapanJAEAconceptfactory
PWBWRLead-cooled fast reactor450150JapanRLNR-TITabandonedon-site
RAPIDLithium-cooled fast reactor101.2JapanCRIEPIabandonedfactory
RBEC-MLead-cooled fast reactor900340RussiaRRC Kurchatovabandonedon-site
RMWRBoiling water reactor955330JapanHitachi / JAERIconcepton-site
RUTA-70Light water reactor70n/aRussiaNIKIET / IPPEconcepton-site
SMARTPressurized water reactor33090KoreaKAERIKorea licenseon-site
SPINNORLead-cooled fast reactor5520IndonesiaITBconceptfactory
SSTARLead-cooled fast reactor4520USAANL / LLNL /
STAR-H2Lead-cooled fast reactor400n/aUSAANL / OrSU
/ TA&M / OhSU
STAR-LMLead-bismuth-cooled fast reactor400178USAANLconceptfactory
SVBR-75/100Lead-cooled fast reactor280100RussiaIPPE / OKB Gidropressconceptfactory
TPSLight water reactor 64 16USAGeneral Atomicsabandonedon-site
UNITHERMPressurized water reactor207RussiaNIKIETconceptfactory
V-SPINNORLead-cooled fast reactor176IndonesiaITBconceptfactory
VBER-300Pressurized water reactor850295RussiaOKBMconcepton-site
VK-300Boiling water reactor750250RussiaNIKIETconcepton-site
VKR-MTLight water reactor890300RussiaRRC Kurchatovabandonedfactory

Note: I'll probably edit this post frequently as I find more information.

Added 2011/06/08: The Union of Concerned Scientists has provided some testimony to Congress on SMRs.

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