opportunities economy issues, innovative concepts, multi ...changingthe licensingrequirementsand...

A review of SMRs regarding safety features, economy issues, innovative concepts, multi-

purpose utilizations, and technological tradeoffs

Afshin Hedayat, Ph.D., Reactor and Nuclear Safety School, Nuclear Science and Technology Research Institute (NSTRI), Atomic

Energy Organization of Iran (AEOI), end of North Karegar street, P.O. Box 14395-836, Tehran, IranEMAIL ADDRESSES: [email protected]; [email protected]

INPRO Dialogue Forum

on“O

pportunities and Challenges in Small M

odular Reactors”Ulsan, Republic of Koria

12-5 Jula

y 2019

In The Name of God, The Merciful

This presentation introduces main results and outcomes

of the review, briefly A complete description is presented in the paper

via corresponding and relevant references

2IN

PRO

Dialogue Forum

on“O

pportunities and Challenges in Sm

all Modular R

eactors”U

lsan, Republic of K

oria

2-5 Julay

2019

Light Water Cooled PWRThe Most Interesting Case

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2-5 Julay2019Ulsan, Republic of Koria

Heavy Water Cooled PWRs4

2-5 Julay 2019Ulsan, Republic of Koria

Gas Cooled Fast SMRs5


Liquid Metal Fast SMRs 6


iPWRs : integral Pressurized Water Reactors

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Ulsan, Republic of Koria

Natural Convection

ForcedConvection 2-5 Julay

2019

Safety Features Enhanced Passive Safety Features

Improved safety by design by means of the optimization of PSA (Probabilistic Safetyassessment) and the elimination of the major accident roots particularly LBLOCA

Less dependency on active safety systems particularly during relevant Design BasisAccident (DBA) such as SBO and LOFA

Improved Inherently Safety Features

Improved defense in depth

Strengthen against Design Extension Conditions (DECs) even Severe Accidents

Contain less radio-active source terms per each module

Higher availability, reliability, and flexibility regarding modular operations

smaller CDF (Core Damage Frequency)

Smaller LERF: Large Early Release Frequency

Smaller and more restricted EPZ (Emergency Planning Zone) 2-5 Julay 2019


8

Economy Issues


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Advantages :

Economy of Scale through compacted and integrated concepts and objects

Lower initial investment

Feasible and profitable Return of Investment (ROI)

Modular and more flexible operation and maintenance

Longer Refueling Cycles and removing soluble burnable poisons (some designs)

Providing multi-utilization industrial applications via Non-electrical heating loops

Providing marine and other remote small power resources

Disadvantages:

Economy of power for developed industrial countries

Changing the licensing requirements and site selection rules for developed countries

Marketing and commercializing weakness

2-5 Julay2019

Innovative Concepts

Integral primary cooling systems & pressurizer Self-pressurizer system Replacing the pump with natural convection Omitting Acid Boric from the RCS Multi-layered strengthen or coated fuels On-line refueling plans (some plans) internal control rod drive mechanism Advanced materials Hybrid plans with green technologies High-tech space applications (Kilopower)


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2-5 Julay2019

Multi-applicable SMRs(particularly suitable for VHTR)

Electricity Generation (all types – differentefficiencies)

Brackish or even sea water desalination (lowtemperature)

Restricted regional heating (low temperature)

Pulp manufacturing (medium temperature)

Oil, Gas, and Petrochemical industries (mediumor high temperature)

Other Industrial (i.e. Iron and Cement)manufacturing (medium or high temperature)

Hydrogen Generation (high temperature)

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2-5 Julay2019

Some particular technological tradeoffs and challenges for iPWRs:

More simplified Fuel Management could be feasible to be used; Stable and sustainable working conditions of the reactor dynamics for normal

operations or even after some small deviations; Some unstable domain after large deviations but only for a fully passive and

integral self-pressurized system; Required some design criteria, some active parts, or particular startup and

load following procedures (for a fully passive and integral self-pressurizer); High Irradiation stress on the reactor core, pressure vessel, and internal I&C; Required comprehensive stability and safety analyses against transients

(anticipated and even unknown), Design Basis Accidents (DBA), and DesignExtension Conditions (DEC); they also need new codes and standards.

2-5 Julay2019


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More Simplified Fuel Management is availableOne Batch

Three Batch (based on the expert rules)2-5 Julay

2019


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For more details, please see: A. Hedayat, (2019), Developing and analyzing long-term fuel management strategies foran advanced Small Modular PWR, Nuclear Engineering and Design, V. 313, pp. 190-213.

BOC EOC(but it should be optimized)

BOC EOCPower Distributions of the Equilibrium Cycle

Stable and sustainable working conditions of the reactor dynamics (i.e. natural circulation, self-pressurization, and inherently safety features)

During normal operations or even after small deviations 2-5 Julay2019


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For more details please follow : A.F. Pilehvar , M.H. Esteki , A. Hedayat, G.R. Ansarifar, (2018). Self-pressurization analysis ofthe natural circulation integral nuclear reactor using a new dynamic model. Nuclear Engineering and Technology, V. 50, pp.654-664.

Stability map (based on the flashing point) due to the reactor power, riser height, and friction factors

by means of the Routh-Hurwitz criterion2-5 Julay

2019


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A new submitted paper: A.F. Pilehvar , M.H. Esteki , G.R. Ansarifar, A. Hedayat, (2019). Stability analysis of anaturalcirculation integrated self-pressurized waterreactor by means of the Routh-Hurwitzcriterion.

The results of the stability maps show that, a reduction in the chimney height leads to instability of the system, likewise, the system remains stable if a minimum mass flow rate is guaranteed.

Right Side :

Such a fully passive system is suitable for

operational conditions not start up procedures

Left Side :

The More friction losses, The higher chimney

The beginning point of flashing at different Power and friction

losses coefficient

The beginning point of flashing at different friction losses coefficient

and chimney height

Larger Leakage, Higher IrradiationHigher Irradiation Stress on the internal I&C and

pressure vessel 2-5 Julay

2019


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For more details, please see: A.Erfanini, A.Hedayat, S.M. Mirvakili, (2016), Neutronic study of a new generation of the small modular pressurized water reactor usingMonte-Carlo simulation, Progress in Nuclear Energy, V. 93, pp. 218-230.

Fully integral Self-pressurizerMay need some active parts (at least heaters)

During power transients (power excursions)2-5 Julay

2019


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For more details, please see: S. K.Moghanaki and A.Hedayat, (2018). Simulation and conceptual analyses of a stable natural corecooling system in an integrated small modular PWR, Nuclear Engineering and Design, V. 332, pp. 357-373.

Without any active part With a 100 KW heater for a 100 MW iPWR

Outstanding & Feasible Stationary ConceptsRegarding safety features, economy issues, innovative concepts, multi-purpose

utilizations, and technological challenges

CAREM 25 (Argentina)SMART (South Koria)ACP100+ (China)MASLWR, NuScale (USA)IRIS (International)

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2-5 Julay2019


General Conclusions

New passive safety systems and inherently safety features that integrated withinthe SMRs are enhanced the safety of the next PWRs (iPWRs) if necessary activesafety systems don’t be forgotten. There are some maturing stationary actionplans such as CAREM, NuScale, ACP100+, and SMART that could be feasible tobe used for developing countries or even new comers in nuclear reactor industry.

Advanced economy issues such as ROI recommend the SMRs, if sometroublesome items will be solved (e.g. they need new codes and standards, orreducing off-site emergency planning to be constructed and developed closer tothe small cities or at least near the industrial regions).

SMRs are highly flexible and robust concepts for advanced innovative energysystems from marine to high-tech space applications.


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General Conclusions

There are a lot of attracting potential applications by means of multi-utilizations,and hybrid designs of sustainable and renewable energies, or even industrial smartgrid systems. Anyway industrial instabilities or un-availabilities should be fullyinvestigated. Using advanced hybrid energy systems and locally integrated smartmanagement systems could be good solutions for the future.

There are many tradeoffs or even advantages to be considered for SMRs such asone-batch type refueling patterns as well as very good potential capacities of thesmall and modular components.

There might be still some technological challenges to take a completetechnological readiness of new iPWRs; particularly due to using natural convectiondriven force; it restricts the design domain, structural design, or even may causesome instabilities during transients; using some stand-by active safety systemsinstead of the fully self-pressurized systems could be a good solution.Furthermore, the higher neutron fluence and leakage should not be forgotten.


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Thank you very much for your time and attention

2-5 Julay

2019

Ulsan, Rep

ublic o

f Koria

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opportunities economy issues, innovative concepts, multi ...changingthe licensingrequirementsand...

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