material research on advanced types of nuclear fuelatf concepts atf fuels doped pellets (cr 2 o 3,...

Material research on advanced types of nuclear fuel

Martin Ševeček, Radomír Řeháček, Stanislav Linhart, Josef Běláč

Jaderné dny 2019, 14. 5. 2019, Plzeň

CONTENT

1. Advanced Nuclear Fuels - ATF a) Fuels with increased resistance

b) Objectives of ATF

c) Programs around the world

d) ATF coatings developing within ALVEL projects

2. Testing of material samples of Zr based alloys a) MCA and POMA projects

b) Objectives of the program

c) Schedule

Jaderné dny 2019, 14. 5. 2019, Plzeň 2

FUEL WITH INCREASED RESISTANCE

All current reactors use combinations of UO2+Zr based alloys

Wide experience and know-how

Developed industrial capacity

Very good behavior (corrosion, hydrogen, high temperature behavior)

Main Negative - Serious Accidents (Hydrogen Generation, Huge Heat from Steam chemical Reaction, Accelerated Degradation) = Fukushima, Three Mile Island

The development of new types of nuclear fuels was initiated by the US Congress following the Fukushima-Daiichi accident

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Objectives of ATF

The main goal is to give the operator more time in case of accident to manage it

At the same time, new types of fuel haven´t to negatively affect reactor operation in other modes (particularly at nominal operation)

It must be also economic, industrially manufactured and compatible with current devices and processes (transport, storage…)


ATF CONCEPTS

ATF Fuels Doped pellets (Cr2O3, Al2O3 ..) High density fuel - silicates, nitrides,

carbides, metal(UN, U2Si3, U2SI5, UC) FCM (Triso analogue)

ATF cladding materials Modification of Zr based alloys

Coatings surface adjustment (ODS)

advanced materials FeCrAl (AISI) Mo-alloys SiC – duplex, triplex

ATF non-fuel components ATCR – Control Rods SiC channel box - BWR


WORLDWIDE PROGRAMS

USA – world leader - WEC (USi+Cr CS; USi+SiC/SiC), GE (FeCrAl, Armor coating), AREVA (Cr PVD + Cr-UO2; SiC/SiC) + support for universities and national labs LTR/LTA – 2018 – FeCrAl-BWR; 2019 – Cr coatings+doped pellets; 2022 – SiC/SiC

France – financed mainly from the US program (Framatome)

Korea – own ambitious program – CrAl coatings + microcell pellets

China – develops almost all published concepts

Russia – started with a greater extent only in 2018 – Cr coatings; 42HNM

+ dozens of smaller groups from all over the world, including the Czech Republic

4. - 6. 4. 2018 Martin Ševeček: ATF - Aktuální stav vývoje 6 Jaderné dny 2019, 14. 5. 2019, Plzeň

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NRC – SCHEDULE LTA/LTR (ONLY THE US)


FRAMATOME – RADIATION

IMAGO – Switzerland – without fuel Vogtle – first ATF files with fuel GOCHROM – Switzerland 4 others in the US research reactors

DEVELOPMENT OF ATF COATINGS IN ALVEL (1)

Focused on modifying current fuel coatings Alloys currently use in VVER reactors are cover with protective coatings of Cr,

CrAl, CrN, TiN and CrN + Cr, which are applied by unique technologies The protective layers are very thin, they can be combined and have different

functions Corrosion protection Prevent individual component interaction Improving mechanical properties or increasing abrasion resistance

Protective layers were selected based on many limitations, e.g.: Low neutron absorption High Temperature Resistance (Melting, Steam Reaction) Material resistance during operation (approx. 320 ° C, aggressive chemical

environment)


DEVELOPMENT OF ATF COATINGS IN ALVEL (2)

In collaboration with FS and FJFI CTU in Prague, coatings are applied to pre-manufactured samples

Samples are tested at UJP Prague for resistance against corrosion and especially resistance to simulated emergency conditions

Application technology and composition of protective layers are continually modified to achieve increased durability and to improve the basic characteristics

Tests are performed on non-irradiated material

The final product will be irradiated in research reactors in the Czech Republic or Russia


PROJECT OF IRRADIATION OF MATERIAL SAMPLES (MCA) AT NPP TEMELÍN

Main project goal: Examine the radiation growth and other mechanical and

material parameters of the coverage samples depending on the neutron fluency received in the VVER-1000 reactor under operating conditions

Other project goal:

support for the advanced fuel licensing process

ensuring correlation between real reactor conditions and experiments conducted in research reactors

A significant part of the project is implemented in the Czech Republic

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DESCRIPTION OF MCA

Název parametru Hodnota

Rozměry souboru pro zkoumání materiálu (průměr × výška), mm

144 × 2647

Počet ampulí pro zkoumání materiálu, ks

6

Délka ampule pro zkoumání materiálu (oddělená část), mm

287

Průměr ampule pro zkoumání materiálu, mm

9,1

Hmotnost souboru pro zkoumání materiálu, kg

8

Stanovená délka životnosti, let 6

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Material Ampoule Content: Fluency Monitors (Fe-54, Cu-63, Nb), samples of advanced types of Zr based alloys


DESCRIPTION OF POMA (1)

POMA + base



POMA – principle of operation



POMA Benefits:

simple activity principle

robust construction

compatibility with AZ fuel files

the device uses only gravitational energy

separation of ampoules is purely mechanical (without remote power or operator)


MCA PROJECT – TOTAL SUMMARY

Duration of the whole project: 2012 – 2024

6 irradiation cycles, until the last MCA is exported

POMA – all PKV / KV tests were completed and trial operation too

The MCA imitator was produced to test POMA before cutting irradiated samples

Every year:

export of one MCA from AZ (after U1C16 will be exported 4psc of MCA), the rest of the MCA goes to another batch

cutting the ampoules using POMA (MCA M1 and M2 were cut off 4/2019)

transporting ampoules in transport container to UJV for analysis


MCA PROJECT - ANALYSIS

Analysis of reference samples and development of methodologies: Development of methodologies and analysis of reference (inactive) samples of

Zr based alloys for future comparison of irradiated material against reference Measurement of geometry (length) of reference samples Micro structural analysis, micro hardness, SEM metallographic Electron microscopy (TEM), degree of recrystallization, grain size, Determination of dislocation type, statistical evaluation of grains Analysis of irradiated samples:

Ampoules cutting, removing irradiated samples and fluence monitors Material analysis (same as on reference samples) Determination of neutron fluence based on fluence monitor activities (Fe, Cu, Nb) RAO storage

Cooperation with UJV Řež and CVŘ


Analysis of reference samples (1)

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HR – TEM phase analysis

Dislocation

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Analysis of reference samples (2)

Grain size and type analysis Recrystallization degree

analysis

CONCLUSION / SUMMARY

ATFs – "the hottest" theme of nuclear energy in recent years

Most activities are initiated and funded by the US, Other countries have gradually joined because of the competition (Korea, Russia, China, Japan)

Dozens of alternative concepts in smaller countries and research groups, including ALVEL, are under development

MCA Project: In April 2019 – the first two sets were separated and transfered to hot cells in ÚJV Řež

The project entered the material analysis phase of irradiated material



THANK YOU FOR YOUR ATTENTION

WWW.ALVEL.EU/EN/

material research on advanced types of nuclear fuelatf concepts atf fuels doped pellets (cr 2 o 3,...

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