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
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