Fuel Cycle Strategies and Options for the Management of Spent Nuclear Fuel and Radioactive Waste

for Countries Embarking on the Use of Nuclear Power

Troyes, France, 14-18 Nov 2016

Spent Nuclear Fuel Management

N. Ivanov (niivanov@npp.bg)

Kozloduy NPP Plc., Bulgaria

1

KNPP OVERVIEW – Units

Kozloduy NPP is situated at the Danuberiver, 200km north from Sofia.

WWER-440 Units

Unit 1 – WWER-440 / B230, commissionedin 1974, shut down at 31.12.2002.

Unit 2 – WWER-440 / B230, commissionedin 1975, shut down at 31.12.2002.

Unit 3 – WWER-440 / B230, commissionedin 1980, shut down at 31.12.2006.

Unit 4 – WWER-440 / B230, commissionedin 1982, shut down at 31.12.2006.

WWER-1000 Units

Unit 5 – WWER-1000/B320, commissionedin 1988, in operation, 23th fuel cycle.

Unit 6 – WWER-1000/B320, commissionedin 1991, in operation, 22th fuel cycle.

2

KNPP OVERVIEW – Units

The WWER-440 units 1-4 are currently under the decommissioningstage and the Nuclear fuel and Core design Department is involved inone of the most important tasks – Induced activity and dose ratescalculations of the structures, components and materials into andsurrounding the reactor core.

The WWER-1000 units are operational and after the program formodernization and overhauling of Unit 5 and Unit 6 is completed it isexpected to prolong their “life” for another 30 years. Unit 5 will receiveits license for a period of 10 years in 2017. In November 2016, the newlylicensed fuel TVSA-12 was loaded in Unit-6. Using this fuel assemblywhich is based on the TVSA fuel assembly will reduce the generatedspent nuclear fuel by up to 10% annually.

3

KNPP - Structure for managing the NFC

Head of Production

Directorate

Chief engineer

Electricity

Production

Head of

Exploitation

Division

Head of

Engineering

Division

Nuclear fuel and

Core design

Department

Reactor-physics

technology section

Nuclear fuel

cycle section

Reactor-physics

calculations section

Spent Fuel Storage

Department

4

KNPP - Structure for managing the NFC

The main tasks of Nuclear fuel and Core design Department:

NFC section is concerned mainly with quality and delivery of the fresh fuelfor the NPP and the transportation of the spent nuclear fuel for its reprocessing,

Reactor-physics calculation section works in the field of neutron physicscharacteristics calculations; core design and reloading calculations; fuel cyclesoptimizations; residual heat and activity calculations (for example spent fuelassemblies, the activity distribution in stainless steel components: protective tubeunit, baffle and barrel).

The main tasks of Reactor-physics technology (RPT) section: fuel loading;fresh and spent fuel in-site movement; nuclear safety surveillance; reactivitycontrol during the start-up physics tests at HZP states, at power increasing anddecreasing states; In-core monitoring system surveillance; Smart fuel data basemaintenance.

Both sections, NFC and RPT observe (as a part of the quality assuranceprogram) the construction process of the fresh fuel assemblies at the manufacturerplant.

At KNPP, Core design department and Reactor-physics technology are indifferent branches. The aim is to ensure a mutual check-up of the refuellingpattern.

5

KNPP –At-reactor pools

Reactor pools at Unit 5 and Unit 6

The full capacity pool 5 – 612 fuelassemblies (at least 163 has to be free whenthe rector is operational).

The full capacity pool 6 – 611 fuelassemblies (at least 163 has to be free whenthe rector is operational).

The nuclear safety is ensured by thedesigned assembly pitch.

The cooling system have to maintainthe water temperature <50°C.

6

KNPP – Wet Storage Facility

Wet Storage Facility (WSF) – for theWWER-440 and WWER-1000 spent fuel –commissioned 1990.

The full WSF capacity – 224 baskets (168 inuse, 56 reserve).

The baskets with the spent fuel are stored inthe chemical desalted water.

Each WWER-440 basket contains 30assemblies with maximum allowed: residual heat15kW and activity 1.73 E+17 Bq.

Each WWER-1000 basket contains 12assemblies with maximum allowed: residual heat20kW and activity 2.41 E+17 Bq.

The nuclear safety is ensured by thedesigned assembly pitch.

The cooling system have to maintain thewater temperature <45°C.

7

KNPP – Dry Storage Facility

Dry Storage Facility (DSF) – for the WWER-440 spent fuel with capacityof 78 containers – commissioned 2011.

In January 2016, the facility has received its first 10 years license. Thetransferring of the spent fuel WWER-440 assemblies has begun.

By the end of 2016, 8 CONSTOR 440/84 loaded with spent fuel assembliesare stored in DSF.

It is expected that by the end of 2026, all the WWER0-440 assemblies willbe stored in the DSF.

8

KNPP STRUCTURE – The Nuclear Fuel Department

• CONSTOR440/84 – 84 assemblies with

maximum allowed: residual heat 20.3kW and

activity 2.3 E+17 Bq.

• Maximum dose rate at the surface of

container is Pγ+n ~ 40-200 µSv/h (middle of

the upper lid). In the terms of reference the

maximum allowed value was 2000 µSv/h

• Maximum surface temperature 90°C.

• Storage term – 50 years.

9

KNPP - Generated Spent Fuel by the end of 2016

•10 160 WWER-440 Fuel Assemblies

• 2 246 WWER-1000 Fuel Assemblies

•Total: ~2150 tHM

10

•3 096 WWER-440 Fuel Assemblies

- 2424 - stored in the Interim WSF

- 672 - stored in the Interim DSF

•1 287 WWER-1000 Fuel Assemblies

- 651 stored in the at-reactor pools

- 636 stored in the Interim WSF

•Total ~ 920 tHM

KNPP - Spent Fuel stored on site by the end of 2016

11

TUK-6 /for WWER-440 SNF/ TUK-13 /for WWER-1000 SNF/

KNPP - SNF Transport Equipment – WSF

12

- 7064 WWER-440 Fuel Assemblies

- 959 WWER-1000 Fuel Assemblies

~ 1260 t HM

1979 – 2016

~ 57% of the generated SNF

was sent for reprocessing in Russia

KNPP – Spent Fuel Shipment for Reprocessing

13

KNPP – SNF Road Transport Equipment

•During transportation a special convoy is arranged, including the vehicle with

the container, fire fighting machine, ambulance, radiation monitoring, security

and police vehicles.

14

KNPP – SNF Inland water Transport Equipment

For SNF shipment along the Danube River a special dumb-barge is used

with a capacity of 8 containers TUK-6 or TUK-13.

•The barge is equipped with passive and powered cooling systems; 2 diesel

generators, decontamination system; radiation monitoring system; containers

parameters control system and other equipment.

15

Main Goals and Principles

To ensure adequate protection to public and environment.

•SNF and RW Management have to ensure that no excessive burdenwill be transferred to the future generations.

•Generation of radioactive waste to be kept to the lowest possible level.

•National responsibility, including application of the principle of themain responsibility of the license holder.

•The National Strategy for Safe Management of SNF and RW assumesannual transportation of 50tHM SNF from Kozloduy NPP fortechnological storage and reprocessing;

•An interim spent fuel wet storage facility (WSF) is in operation on site.The designed capacity of the WSF is 168 baskets (~ 2000 WWER-1000SFA);

• A long-term spent fuel dry storage facility for WWER-440 wascommissioned (funded jointly by the EBRD and Kozloduy NPP).

Strategy for Safe Management of SNF and RW

16

The option Transportation for reprocessing

of 50tHM SNF for reprocessing annually:

is based on approved technologies;

complies with the principle

not to burden the future generations;

is technically implementable;

is financially secured;

Other options:

allows taking interim decisions as:

storing the SNF on site in the existing WSF and the DSF

for WWER-440 until reprocessing or disposal.

Plans for building DSF for the WWER-1000 fuel.

KNPP – Optimal strategy for the SNF Management

17

Defining back-end fuel strategy we should consider that: Spent Fuel should be safely stored until reprocessing or disposal. The safety of SF should be ensured at all times: during storage period, extended storage

periods and transportation after non defined storage period…That is why for Interim Storage we need

Dual Purpose Casks – Transport / Storage / Transport

Strategy for SF management should be re-examined with respect to the

various options available:

• Availability of reprocessing and/or disposal technology;

• Design of the Front End – Fuel Cycle Design should offer reliableBack End solutions and/or fuel leasing option.

• Storage option assures safely storing until spent fuel reprocessing or disposal.The presence of operating Wet and Dry Spent Fuel Storage Facilities, where the assembliesfrom both types of reactors are stored, provide safe effective and flexible managementof Nuclear Fuel Cycle back-end.

• Reprocessing SNF provides long term strategic flexibility and confidence, saves naturalresources, reduces the volume of high-level waste to be disposed.

KNPP - SNF Management Conclusions

18

THANK YOU

FOR YOUR

ATTENTION!