IRIS reactor

New concepts based on passive safety presently under study are the Pebble Bed Modular Reactor (PBMR - gas cooled, high temperature, helium operated, direct cycle turbine generators) supported by an international group based in South Africa, the IRIS reactor (a PWR with steam generators integrated in the reactor pressure vessel) and the already mentioned APIOOO. Other concepts still under study but already proposed exist... 

PETROVIC, B., FRANCESCHINI, F., Fuel management options in IRIS reactor for the extended cycle. Nuclear Option in Countries with Small and Medium Electricity Grids (Proc. 5 Inti. Conf, Dubrovnik, Croatia, May 16-20, 2004) HND, Zagreb (2004). 

CARELLI, M.D., et al.. The design and safety features of the IRIS reactor. Nuclear Engineering and Design, 230 (2004), 151-167. 

PETROVIC, B., FRANCESCHINI, F, Fuel management approach in IRIS reactor, LAS-ANS, 2004 (Proc. Int. Conf, Cancun, Mexico, July 11-16, 2004), LAS-ANS. CARELLI, M.D., A global approach to nuclear power renaissance. Nuclear News, 46, No. 10 (2003), 32-42. 

Carelli, M.D., Conway, L.E., Oriani, L., April 06—11,2003a. Safety features of the IRIS reactor. In Nuclear Mathematical and Computational Sciences A Century in Review, a Century Anew. Gatlinhurg, Tennessee. 

Although churn-turbulent flow iri the reactor is usually a worst case (giving rise to the greatest amount of vapour/ liquid disengagement), the relief system can be sized on the basis of homogeneous or bubbly flow if they can be shown to occur. Section... 

Notice again that solving the rate-of-change form of the mass balance requires more inform.ation (here the rate of reaction) and more effort than solving the difference form of the mass balance. However, we also get more information—the amount of each species present as a function of time. In Sec. 2.4, which is optional and more difficult, we consider another, even deeper level of description, where not only is time allowed to vary, but the system is.not spatially homogeneous that is, the composition in the reactor varies from point to point. However, this section is not for the faint-hearted and is best considered after a course iri fluid mechanics. B... 

Heat and mass transfer coefficients can be used to interrogate the importance of external transport phenomena and how to choose reactor size. The latter controls (i) pressure drop, (ii) residence time and thus reactant conversion or flow rate and thus power generated, (iri) the effective reaction rate and thus the process efficiency, (iv) the temperature and (v) whether a system is kinetically controlled and thus ideal for extraction of catalytic kinetics. Another application of Nu and Sh is that a 2D or 3D problem can be reduced to a computationally tractable problem by approximating the transverse transport phenomena using overall transport correlations. Such pseudo-2 D models (also called heterogeneous ID models for catalytic systems) have been used to explore the stability and performance of microbumers with a significantly lower computational effort than CFD models (e.g. [23-25]). 

Integral type pressurized water reactors targeted for near term deployment SMART (the Republic of Korea), IRIS (the International Consortium, led by Westinghouse, USA), CAREM (Argentina), and SCOR (AREVA-CEA, France) ... 

To facilitate the adjustment of safety requirements and regulations, the designers of IRIS have kept informed the IAEA of their activities from an early stage and are planning to have an IAEA safety review. The need of an early involvement of regulators was noted in the presentations on the advanced high temperature gas cooled reactors HTR-PM and PBMR-400. 

Integral design of primary circuit Near-term PWRs SMART, IRIS, CAREM, SCOR, SAKHA-92, ABV, RIT, FBNR Lead or lead-bismuth cooled reactors SVBR-75/100, STAR family , SPINNOR/VSPINNOR Non-conventional designs MARS (RRC Kurchatov Institute ), CHTR, ELENA... 

The technology of barge-mounted NPPs Small PWRs ABV, KLT-40S, VBER, RTF, NIKA-70, an option for IRIS Lead-bismuth cooled reactors an option for SVBR-75/100 Non-conventional designs a floating NPP option is envisaged for MARS... 

Early involvement of regulators in the design development process Near term PWRs IRIS, SMART High temperature gas cooled reactors HTGR, HTR PM... 

Minimization of safety-related costs through design optimization Near-term PWRs SMART, CAREM, IRIS, SAKHA-92, ABV, RIT Small PWR FBNR - fixed bed modular PWR Lead-bismuth cooled modular reactor SVBR-75/100 Non-conventional designs CHTR... 

Once it was established that this new reactor was to be deployed world-wide, it followed that to be readily accepted internationally, it had to be developed internationally, i.e., it had to address international requirements, needs and even cultures. Hence, the IRIS approach, as emphasized by the first letter (International) of its acronym From the very beginning, IRIS was going to be designed and subsequently fabricated, deployed and serviced by an international partnership, where all team members were stakeholders in the project. 

By utilizing the upper head region of the reactor vessel, the IRIS pressurizer provides very large water and steam volume, as compared to plants with a traditional, separate, pressurizer vessel. The IRIS pressurizer has a total volume of 71 m, which includes a steam volume of 49 m. The steam volume is about 1.6 times bigger than the APIOOO pressurizer steam space, while IRIS has less than 1/3 the core power. The large steam volume to power ratio is a key reason why IRIS does not require pressurizer sprays, which are used in current PWRs to prevent the pressurizer safety valves from lifting for any design basis heatup transients. 

Reactor coolant pumps - The IRIS RCPs [12] are of a spool type, which has been used in marine applications, and are being designed and will soon be supplied for chemical plant applications requiring high flow rates and low developed head. The motor and pump consist of two concentric cylinders, where the outer ring is the stationary stator and the... 

Steam generators - The IRIS SGs are once-through, helical-coil tube bundle design with the primary fluid outside the tubes [6]. As shown in Fig. 4, eight steam generator modules are located in the annular space between the core barrel (outside diameter 2.85 m) and the reactor vessel (inside diameter 6.21 m). 

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