issues for increasing burnup - international atomic …€¦ · · 2014-04-084 p.blanpain –...

BU FUEL1 P.Blanpain – IAEA/TWG-FPT- Vienna – April 2013

Issues for Increasing Burnup

Patrick Blanpain

TWGFPT, Vienna, April 24 – 26, 2013


ContentCountry Reports AnalysisIssues for Increasing Burnup

Burnup trends for various types of fuels [Ref.6]


Country Reports

Answers from 24 countries

PWR, BWR, VVER, PHWR

Data: 2010 to 2013 Japan: data before March 2011. Update available on the XL file Germany: proprietary information

Unit: Batch avg. discharge BU (MWd/kg) Assembly Avg. discharge BU (USA)


BU analysis – PWR

Y

YY

MOX

No inf.Germany

Opt Zirlo488 EFPD14x144.539 – 56*USAM51817x174.044UK

Duplex D41215x154.9557 - 58SwitzerlandM51215x154.143 - 51Sweden

Zirlo1817x174.750Spain

M51215x154.451NetherlandZirlo15 - 1717x17, 16X164.538 - 46Korea

Zirlo,MDA,NDA

1314x144.840 - 51Japan

M51817x174.545 - 55FranceM51817x174.545.0ChinaM51316x164.035.6 – 47.3BrazilM51817x174.647.9 - 50.5Belgium

Cladding**

Cycle length (m)

FA array**% U5**BU range

Country

* Assembly avg. ** Data corresponding to the highest burnups


BU analysis – BWR

Y

Y

MOX

No inf.Germany

Zy-2650 EFPD10 x 104.2039.1 – 49.9*USA

Zy2/Liner1210 x 104.2553 - 55Switzerland

Zy2/Liner1210 x 103.8543 - 45Sweden

No inf.Spain

Zy2139 x 93.746Japan

Zy2186 x 64.721India

Zy21210 x 103.5842 - 44Finland

CladdingCycle length (m)

FA array% U5BU rangeCountry

* Assembly avg


BU analysis – VVER

E110121274.1142.7 – 48.9Ukraine

E11011hex4.8748Slovakia

E110121274.2541.6 - 52Russian Federation

E110123494.2040.0Hungary

E11012hex4.3742.9Finland

E110121274.3829 - 52Czech Republic

E11012hex4.1042China

Zr 1% Nb123314.2548.8Bulgaria

CladdingCycle length (m)

FA array% U5BU RangeCountry


BU analysis – PHWR

Zy-4On-line19/37NU7.0India

On-lineRomania

Zy-41537NU7.2Korea

On-line37NU7.2China

On-line28/37NUCanada

Zy-4On-line36/37NU – 0.857.3 – 10.5Argentina

CladdingCycle lenght

Array% U5BU RangeCountry


Burnup analysis (1)

PWRs Average batch discharge burnups are currently in the range of 40 – 58 GWd/tM Highest batch discharge BU (58) reported by Switzerland. Batch average disch. BU 65 in 2016

U5 enrichments in the range of 4 – 5%

BWRs Average batch discharge burnups are currently in the range of 40 – 55 GWd/tM Highest batch discharge BU (55) reported by Switzerland. U5 enrichments in the range of 3.60 – 4.25%

VVERs Average batch discharge burnups are currently in the range of 40 – 52 GWd/tM Highest batch discharge BU (52) reported by Russian Federation.

PHWRs PHWR reactors are refuelled continuously on-power Burnup around 7 GWd/tM


BU analysis (2)– PHWR

PHWR reactors are refuelled continuously on-powerArgentina Embalse with natural uranium and Atucha-1 with slightly enriched

uranium (0.85%) since year 2000. The average fuel discharge burnupsachieved in 2010 were 10563 MWd/tU at Atucha-1 and 7292 MWd/tU at Embalse.

Romania The average fuel discharge burnup achieved in 2010 was 169.8 MWh/kgU

at Unit 1 and 180.1 MWh/kgU at Unit 2


BU analysis (3) - MOX

Some countries have chosen the option of reprocessing spent fuel. Thus, resulting in a certain quantity of fissile Pu, which can be used together with UO2 to manufacture so called mixed-oxide fuel (MOX), as well as some amount of reprocessed uranium. Also, theoption of using weapons grade high enriched uranium and plutonium has been considered.

MOX fuel: France, Germany and Japan No more MOX fuel in Belgian and Swiss reactors Four WG MOX assemblies recently irradiated in USA (Catawba PWR)


BU analysis (4) - Trends in Germany

There is no generic licensing burnup limit for German plants. According to the reports on safety technical boundary conditionsthe situation is (rod averaged max.burnup): PWR:

UO2: between 71 and 80 MWd/kgU MOX: between 53 and 76 MWd/kgHM

BWR: UO2: 82 MWd/kgU MOX: 75 MWd/kg HM

[Ref.6]

[P-B. Hoffmann,

Personal Communication]


BU analysis (5) – Trends in USA

The average burnup at discharge from US PWRs are currently in the range of 40-56 GWd/tM and from US BWRs in the range of 40-50 GWd/tM. The PWRs have levelled off and the BWR are still increasing slightly approaching the NRC regulatory limit of 62.5GWd/tM peak rod.

[Ref. 4]


BU analysis (6) – Trends in France

MOX Since 2007, the “MOX Parity” fuel management is now deployed in 22

French 900 MWe NPPs and allows 4 one-year cycles of insertion, and the same assembly discharge burnup for UO2 and MOX fuel (enrichment of UO2 is 3.7% U-235 and the average Pu content of the MOX assemblies is equivalent to 3.7% U-235).

Burnups The need for very high burnup limits is somewhat alleviated in France by

the use of fuel recycle technology. High burnups degrade the isotopic composition and “quality” of reprocessed fuels.

A limit of 62 GWd/tM has been licensed for the “GALICE” fuel management in the 1 300 MWe NPPs, which has been implemented in only one NPP, to gather in-reactor feedback.


Issues for Increasing Burnup

A trend towards increasing the discharge burnup of nuclear fuel has been a feature of the operation of all types of nuclear power plant for many years. The increase of fuel burnup, and a concurrent increase in fuel duty, has been implemented in response to the economic challenge to reduce costs associated with nuclear power. Increased dwell allows smaller fuel inventories, and reduced spent fuel arisings. It is also possible to design longer fuel cycles in the reactor, which can mean higher availability and capacity factors. However, there are also increased costs associated with high burnup, for example, increased enrichment, poison loadings, which can decrease efficiency and also meeting new challenges to fuel integrity and performance.

In addition to potential technical issues, the two major constraints to achieving higher burnup are the regulatory limits and the 5% limit on U235 enrichment. The regulatory limits are set to ensure sufficient margins towards the fuel design criteria.


Enrichment

Depending on the assumptions, enrichment > 5% required for > 60 GWd/tM

[Ref. 2]


Economics

Depending on the assumptions, fuel cycle costs estimates tend to increase with burnup beyond 55 – 70 GWd/tM


LWR Fuel Burnup Limits

Potential limiting factors: Pellet cladding interaction Rod pressure Corrosion (oxide layer) Hydrogen pickup (cladding embrittlement) …

What is the burnup limit? Examples of 100 GWd/tM reported Possibility to tweak current UO2 pellet fuel system to > 75 GWd/tM More importantly, what are the margins?


Development Needed for High Burnup

Fuel performance Fission gas release Swelling / PCI Cladding behavior High burnup structure (HBS) Off-normal behavior not well known (RIA, ATWS, LOCA)

Criticality limits Enrichment plants Fuel fabrication plants Transportation Reactor storage racks

Spent fuel Storage Transportation

Cladding properties


Off- Normal Behavior: LOCA


Off-Normal Behavior: LOCA

or

The US-NRC – Studsvik Tests


CONSEQUENCES:P. Clifford / US-NRC – Regulatory – (Proposal

at LOCA Workshop in Lyon, May 2012)

Fuel dispersal:“Possible near-term action plan:

Interim requirements consisting of prescriptive limits on population of burst fuel rods.

- LOCA:- Less than 10% burst rods.- No burst rods above 45 GWd/MTU.- Non-LOCA:- No burst rods (No DNB failures in high burnup fuel rods above system pressure).

Fuel design and/or fuel management changes may be necessary to comply with interim requirements.

Moratorium on fuel rod burnup extensions and fuel design changes which promote fuel dispersal.”

NOT IMPLEMENTED in the current US-NRC LOCA RULEMAKING


Summary

Burnups approaching the regulatory limits and the 5% enrichment limit

Economic advantage does not appear to be great

Still some room for improvement in burnup performance

New nuclear infrastructure required beyond ~ 65 GWd/tM

Significant R&D / qualification effort still needed (off-normal behavior)


References

1. IAEA / TWGFPT Country Reports2. “Very High Burn-ups in Light Water Reactors” OECD 2006 NEA

N°62243. IAEA TM on High Burnup Fuel Experience and Economics. Sofia

26 – 28 September 20064. “High Burnup Fuel Design Issues and Consequences” A.N.T.

International, October 20125. “Nuclear Fuel Safety Criteria Technical Review” OECD 2012, NEA

N°70726. “Impact of High Burnup Uranium Oxide and Mixed Uranium–

plutonium Oxide Water Reactor Fuel on Spent Fuel Management”IAEA Nuclear Energy Series N° NF-T-3.8, 2011

Presentation title – Presenter/ref. - 24 April 2013 - p.24

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Presentation title – Presenter/ref. - 24 April 2013 - p.24

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