Some Technical and Operational Issues Related to the

Transportation of High-burnup SNF and Mixed Oxide Fuels in Russia

25 Sep 2019

Maria Dedova

Vladimir Ipatov

State Atomic Energy Corp. ROSATOM

State atomic energy corporation “Rosatom”

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SNF generation and managing strategies

• Every year in Russia 650-700 tons of SNF is unloaded from NPPs (as electricity is generated at nuclear

power plants with RBMK, VVER and BN reactors).

• There is a capacity either store or to reprocess all generated SNF.

• The increase in the SNF accumulation due to new NPP units commissioning is partly compensated by

decommissioning of the "old" ones

(example, LNPP-2 the first VVER unit is introduced, LNPP- (1) the first RBMK unit is stopped).

The operation of all operating NPPs with VVER-1000 was transferred to the campaign consisting of 3

cycles 18 months each with an average burnup about 50 GW * day / tU.

Leningradskaya NPP-1 Leningradskaya NPP-2

Fuel characteristics on example of VVER spent fuel assemblies

Year of implementation 1998 2003 2006 2006 2010 2022

SFA type ТВСА ТВС-2 ТВСА-

АЛЬФА ТВС-2М

ТВСА-

PLUS ТВС-509

Average enrichment of

replenishment fuel at 235U,% 4.26 4.26 до 4.95 до 4.95 до 4.95 до 4.95

The number of replenishment

fuel assemblies, pcs 42 54 36 60 60 72

Average burnup, MWd/kU 55 55 до 68 до 68 до 68 до 70

Fuel cycle, eff. days 4×

(310-320)

3×

(350-370)

5×

(310-320)

3×

(480-510)

3×

(480-510)

3×

(480-510)

Gamma radiation intensity increase 41%

Neutron radiation intensity increase 146%

SFA residual heat increase 45-55%

Uneven burnup distribution

Data shown for on site wet storage time - 9 years

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Operational constraints in managing higher burnup VVER spent fuel in Russia

The elongated fuel column in modern SFA designs

with higher burnup is the main problem for using

“historical” fleet of transport containers.

Maximum zircaloy cladding temperature of fuel rods

is limited to 350 ° C. It’s a significant limiting factor

for package designers developing casks for SNF

with increased enrichment and burnup and possibly

shorter cooling time and increased capacity.

Package designers are forced to include excessive

conservative solutions in the packaging design,

which negatively affects the competitiveness of both

the packaging itself and its handling processes.

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Document (guide) for analysis of radiation safety during handling

of spent nuclear fuel from VVER and RBMK reactors

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Limitations of document:

- limited possibility of use with foreign

customers;

- maximum burnup of SNF of VVER

reactor is 68 MWd/kU;

- 235U maximum fuel enrichment is limited

to 4.81%;

- lack of SNF parameters for new reactors

such as VVER-1200/1300 / TOI, BN-

600/800 type, etc .;

- lack of data on induced radioactivity;

- lack of data on the axial distribution of

heat, gamma and neutron sources in SFA.

Radiation and Thermophysical Characteristics of Spent Nuclear Fuel from VVER and

RBMK. RB-093-14. – M.: Rostechnadzor, 2014

We would support the creation of a unified and

universally recognized international database on the

characteristics of SNF from various power reactors,

including VVER, RBMK, PWR, etc. An example is

the international library of criticality benchmark

experiments used in nuclear safety analysis.

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• The existing international database of

experimental data on the SNF isotopic

composition includes only 4 SFAs types of

VVER-1000 reactor. It needs further filling

including increased burnup.

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• Cooling surface finning (optimization

by shape, design, material, height and

gaps between fins);

• Advanced polymer-based neutron

protection;

• Insertion of neutron-absorbing

elements (a composite based on boron

carbide) in the structure of cask body.

Technical solutions used in design of transport/storage packagings for SNF

with higher radiation and thermal characteristics

Mixed fuels

In Russia, as applied to VVER, work is underway to develop a fuel cycle on REMIX (plutonium content is

at the level of that of original (reprocessed) SNF).

The nuclear REMIX fuel developed in Russia (REMIX, from regenerated mixture) is obtained from an

undivided mixture of regenerated uranium and plutonium, which is formed during SNF reprocessing with

addition of enriched uranium to the isolated mixture.

MOX and SNUP (SNUP -mixed uranium and plutonium nitrides) are designed under the Proryv

'Breakthrough‘ project on Closure the nuclear fuel cycle.

Any new types of fuel assemblies undergo a full assessment cycle, including testing) in order to justify

safety, including during storage and transportation. At present, fuel assemblies with REMIX (regenerated

mixture) , MOX, and SNUP are irradiated in the nuclear power plants and RR and are studied in material

science laboratories.

Testing of fuel assemblies with REMIX fuel is now underway (NPP and RR)

REMIX FA were loaded into the VVER-1000 reactor core of power unit No. 3 of the Balakovo NPP for life

tests, which should confirm the operability of the new fuel.

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REMIX fuel strategy road map

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2019 2018

R&D on calculated and experimental justification of the operability of REMIX

fuel for VVER-1000/1200 reactors

The main objectives of the 2020 work on the project for

REMIX fuels transport:

Assessment of six experimental REMIX assemblies

transportation in TUK-13 (initially designed for SNF

VVER-1000);

REMIX assemblies will be transported in a packaging

TYK-13 designed for SNF of VVER-1000

Design of a prototype canister and a basket for fuel

assemblies with REMIX fuel to insert TUK-13;

Analysis of transport and technological solutions of the

nuclear fuel handling system during the TVS-2M REMIX

fuel handling operations at NPP

The ultimate goal of the R&D project “Calculation and Experimental

Feasibility of REMIX Fuel 1000/1200” is to justify the feasibility and

safety of the pilot operation of the VVER reactor core with a new type

of regenerated fuel containing a mixture of plutonium and regenerated

uranium (REMIX fuel) extracted during reprocessing ), as well as a

safety justification for the means of transportation and transport and

technological schemes of facilities for the tasks of handling new fuel.

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MOX-fuel on Beloyarskaya NPP

Since the commissioning of Unit 4 of the

Beloyarsk NPP, the BN-800 reactor has been

operating with a hybrid core, which includes fuel

assemblies with both uranium oxide fuel and MOX

fuel.

In accordance with the R&D Program for the BN-

800 core with a full load of MOX fuel starting from

the 8th reloading BN-800 core will be loaded with

MOX fuel only.

After irradiation in the reactor core spent fuel

assemblies are temporary stored in wet storage

stored for at least 3 years or for the period justified

in the certificate of approval for the design of

packaging and transportation and not longer than

10 years in accordance with the requirements of

the technical conditions on fuel assemblies.

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MOX-fuel on BN-800, Beloyarskaya NPP

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• A fuel assembly with MOX fuel differs from a fuel assembly with uranium fuel in attachment unit and

shank design due to remote fuel assembly fabrication procedures for MOX fuel.

• The design and manufacturing technology for fuel rods with tablet MOX fuel were developed by VNIINM

and now MCC and Mayak fabricate fuel assemblies,

• fuel assemblies with vibro-packed MOX fuel were developed by JSC SSC RIAR and is fabricated there.

MOX-fuel on Beloyarskaya NPP, plans on fuel removal

Based on the filling of wet storage and the minimum cooling time for SFAs in it (3 years), it

is scheduled to begin the removal of uranium SFA in 2021.

Spent radial blanket SFA accumulate in wet storage unevenly so it is planed to remove

them when amount is sufficient to load full basket, depending on container parameters.

After uranium SFA are removed from wet storage, removal of SFA with MOX fuel is

planned no later than 2027 to ensure the fulfillment of regulatory requirement for

emergency core unloading at any time.

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Plans on MOX-fuel transport

Spent MOX-fuel is considered to be transported to

reprocessing facility in TUK-11BN cask, that was initially

designed and certified for 35 BN-600 uranium SFA.

Presumably only assemblies with fuel-grade plutonium

will fit with a restriction on number of loaded assemblies.

For spent MOX assemblies containing reactor-grade Pu

a new designed cask is required

The discussion is on to adapt TUK-109T and TUK-140 for

this purpose.

TUK-109T was initially designed and certified for RBMK-

1000 SFA

TUK-140 was initially designed and certified for VVER-

440 SFA

TUK-11BN

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Harmonization between Russian and IAEA transport safety regulations

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Based on recommendations and guides similar national documents are developed

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Regulation of dry container storage in the Russia

“

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• Safety regulations for Transport of Radioactive Materials” (NP-053-16) contain requirements

for packages with RM only in terms of safety during transport.

• There are no specific safety requirements for design of containers for long-term storage of

SNF

• Since VVER SNF is systematically reprocessed, there is no significant experience in the

transportation of dual-purpose TUKs with VVER SNF after long-term storage.

• In short term it is planned to construct a long-term storage site of VVER-1000 spent nuclear

fuel in dual-purpose containers and to develop requirements for dual-purpose or for storage

containers. This work is aiming on foreign market and should become a reference for

countries where Russian designed nuclear power plants are constructed.

Long-term stored AMB reactors SNF removal from reactor site wet

storage at Beloyarskaya NPP

After long-term storage (up to 50 years), spent nuclear fuel of finally shut down AMB-100

and AMB-200 reactors, wet-stored in baskets, was transported in TUK-84/1 for future

reprocessing from the reactor site of Beloyarskaya NPP.

TUK-84/1 is 15-meter-long cylinder weighing 90 tons.

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FMBA (Federal Medical

and Biological Agency)

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Certification procedure for transport packages

Application+

SAR

State Atomic Energy Corporation“Rosatom”

Approved by Head of Nuclear

and Radiation safety and Licensing Department

Approved by Federal

Agencies and Services

Approval of certificate by Deputy Director General

of Rosatom

Certificate of approval for

package design

Federal Environmental, Industrial and

Nuclear Supervision Service

(Rostechnadzor)

Independent experts organization

Expert conclusion Independent Criticality

assessment IPPE, Obninsk

Safety assessment of transport of higher burnup SFA and MOX fuel

Within the framework of certification and examination procedures, PDSR reports are submitted on the

justification of compliance with the design requirements of the requirements of NP-053-16 and SSR-6 to

independent expert organization. Russian regulations NP-053-16 almost completely correspond with the

The requirements for PDSR contents and listed in local document The order of safety expertise for

package designs and transport conditions 1/17-NPA and it does not contain special requirements for

spent nuclear fuel with a higher burnup content or for mixed fuels. The expert organization may require

additional data and confirmations.

When assessing safety, experts adhere to the conservative principles :

For example: Criticality assessment for SNF is performed in assumption that the fuel is fresh and for

mixed fuel all plutonium conservatively considered Pu239.

A new requirement of Russian regulatory body (Rostechnadzor): licensing for all computer codes used

to assess compliance of package design. According to regulator this licensing procedure involves

directing not only verifying data but the software itself to scientifically support organization of regulator.

Which is a problem due to software publisher’s restriction on transferring their copyright-protected

product to third parties.

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New cask designs dedicated to the transport of higher burnup SNF

For mass transportation of SFA VVER-1000 with high burnup, new containers

TUK-141O,

TUK-137D were developed and certified.

For VVER-440 SNF –

TUK-140

Alternative designs are considered.

There is a demand on a new container for spent MOX-fuel. Now it is met by adapting existing

containers for SNF by limiting the number of assemblies loaded.

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TUK family designed by ECNC

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ТУК-141 for VVER-1000 spent nuclear fuel assemblies

The TUK-141 transport packaging set is intended for:

• Safe transportation of spent fuel assemblies of all

modifications of the VVER-1000 reactor from the

territory of the nuclear power plant on public railways

and highways in horizontal position on a special

railway conveyor or trailer;

• Long-term storage of SFA in an upright position in a

container storage or container site for at least 60

years.

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Fuel burnup, max.

- 68 GWd/tU

TUK-141 cask for higher burnup fuel

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(ductile cast iron)

ТУК-141 operational tests

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Drop tests of TUK-140

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TUK-140 with specialized car ТК-Е-140

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Drop test of container body made of ductile cast iron under low temperature

(TUK-128 for RR SNF)

t = - 61,6 С

The tests confirmed brittle fracture resistance

of the ductile iron body at low temperatures.

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TUK-137D for SNF VVER-1000/1200, designed by VNIIEF

Initial enrichment of SFA U-235, %

4,95

Capacity, number of SFA 20

Minimum cooling time, years 9

Long-term storage, years 50

Total weight of the package, tons 120

Height of the TUK with shock absorbers, mm 6 260

Maximum diameter, mm 2 650

Inner cavity diameter, mm 1 510

TUK-137D is intended for transportation and long-term storage

(up to 50 years) SFA with high burnup (up to 68 MWd/kgU)

VVER-1000/1200.

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Drop test of analogue TUK-109T (for RBMK-1000 SNF)

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Drop test of analogue TUK-109T

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Calculation/test comparison for TUK-109T drop tests

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experiment calculation

experiment test

puncture depth 75 mm 76 mm

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Thank you for your attention!

Maria Dedova, Leading specialist

Department of Nuclear and Radiation Safety

+7 (499) 949-22-31

MDDedova@rosatom.ru

www.rosatom.ru

Defense in depth requirement application to transport of higher burnup/MOX

spent fuel

The implementation of the concept of defense in depth based on the use of a system of

physical barriers to the spread of ionizing radiation and radioactive substances into the

environment, systems of technical and organizational measures to protect barriers and

maintain their effectiveness, as well as to protect personnel, the public and the environment,

is provided for in Russian regulatory documentation. The main requirement of the Regulatory

Authority for packaging is to comply with the requirements of regulatory documents

applicable.

All transportation of spent nuclear fuel in the Russian Federation is carried out with the

requirement of defense in depth. There are no specific features for MOX and UO2.

Additional barriers are added if needed, as for example damaged assemblies are transported

in canisters

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Capabilities of the Heat dissipation system

of TUK-137 family designed by VNIIEF

The main factors determining the loading of TUKs are

outer dimension limitation and residual heat release of loaded SNF

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Maximum

TUK diameter,

mm

Outer diameter of the

outer shell, mm

TUK outer surface

area (height 4 m)

square meters

Thermal

Convecti

on, kWt

Thermal

radiatio

n,

kWt

Outer

Surface

temperature.

C

Loaded,

kW