IAEA-CN-114/B-1
The Results of Russian Nuclear Civil Ships RP Operation and the
Experience of their Specified Lifetime Extension
V.I. Kostin1, Yu.K. Panov1, V.I. Polunichev1, O.A. Yakovlev1,
M.M. Kashka2, N.V. Mantula2
1
OKB Mechanical Engineering (OKBM),
Nizhny Novgorod, Russia
2
JSC "МSCO"
Murmansk, Russia
Abstract. The report presents the state of Russian nuclear fleet, gives short results of the nuclear ship reactor
plants operation and the main causes influencing the damageability and residual life time of the most loaded
units and elements of the systems and equipment. A list of modes decreasing the damaging thermocyclic effects
upon RP elements is presented. Reactor plants state after the development of primarily determined reliability
indices is analyzed, the practice of systems and equipment service life extension without factory repair is
described. The results of the complex “Program of the Nuclear Ships NSSP Life Time Extension to 150000
hours and Service Life Extension to 30 years” (further called “Program …”) are presented; in accordance with
this program OKBM and MMP together with the other organizations realize the measures provided in the
“Program…”, first of all at the nuclear ice breakers “Arctika” and “Taimir”.
Introduction
Of the built nine nuclear ships seven are operated now, the nuclear ice-breaker “Lenin” is
altered into a museum and the nuclear ice-breaker “Sibir” has a long-term closedown. The
other ice-breakers are operated and with the existing now model of RP application they will
reach the specified service life of 100 000 hours in 2004 –2009.
Table 1 – Operating time of nuclear ships RPs
Ship name
"Arctika"
"Sibir"
"Rossia"
"Sovetskiy
Soyuz"
"Jamal"
"Taimir"
"Vaigach"
"Sevmorput"
Average RP
The year of operating
putting into time a year
operation (thousand
of hours)*
RP
RP operating time
operating RP service
100 000 hours
time before life before
01.01.04, 01.01.04, The year of Service
(years)
(thousand
life,
operating
of hours)
(years)
time end
RP operating time
150 000 hours /
175 000 hours
The year of
operating
time end
Service
life,
(years)
1977
1985
6.22
6.88
95
96
19
18
2006***
18
2004 /
2006
2012 / -
1989
6.58
78
14
2007
18
2015 / -
25 / -
1992
1989
1990
1988
6.2
6.77
6.53
6.53
65
95
87
86
11
14
13
15
2009
2004
2006
2006
16
15
15
18
2018 / 2012 / 2014 / 2014 / -
29 / 22 / 23 / 25 / -
1975
5.95
146
29
**
1990
15
29 / 32
26 / -
Note:* - The time of temporary ship closedown was not taken into account.
**
- The operation of the ice-breaker “Sibir” was interrupted in 1992.
***
- Ice-breaker “Rossia” will be removed from operation before 2005.
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IAEA-CN-114/B-1
1 Operation results
Altogether 15 reactors of OK-900 and KLT-40 type, the total operating time of which is 265
reactor-years are operated in Russian nuclear fleet.
It should be noted that nuclear ice-breakers operation was more intensive, than it was first
agreed in the performance specification for the RP because more than (85-90)% of time they
operate in the ice under the conditions of high shock and vibration loads. Main RP equipment
operated intensively and rapidly spent the life time, the periods of uninterrupted operation
often lasted more than 10 months a year (table 2).
Table 2 – Main operational data of nuclear ice-breakers and RPs before 01.01.04.
Ice-breaker
RP
operating
time,
hours.
Reactor
power
generation
TW·hour.
Average
reactor
power,
%Nnom
Р1
Р2
Р1
"Rossiya"
Р2
"Sovetskiy Р1
Souyz"
Р2
Р1
"Yamal"
Р2
"Taimir"
Р
"Vaigach"
Р
"Sevmorput" Р
145508
146026
96016
95506
77541
77084
65439
65024
95059
87298
85515
9.521
8.641
6.519
6.473
4.971
5.082
3.893
4.478
7.492
7.435
4.574
0.38
0.35
0.40
0.40
0.37
0.39
0.35
0.40
0.46
0.50
0.40
"Arctika"
Number
of the
performed
core
refuelings
7
6
3
3
3
3
2
2
5
4
3
The passed way
(miles)
Includin
In total
g in the
ice
Number
of the
conducted
ships
954767
845067
3061
601242
540193
1555
406160
344456
698
384066
326713
828
531849
452578
314517
485089
394403
118476
1371
1064
-
The designing organizations together with the operating organization (JSC “MMP’) worked at
the perfection of individual RP elements and their operation conditions.
Large work on the increase of the cores reliability have been performed.
The first core sets mounted at the nuclear ice-breaker “Lenin” in 1970 at (0,9-1,1) ×106
MW/hr power output have practically reached the extreme state as for leak-tightness and the
latest core sets successfully work out (1,9-2,6) ×106 MW/hr energy supply with practically
leak-tight FE claddings. Some RP cores of nuclear ice-breakers exceeded specified energy
supply without any features of loss of tightness owing to the reactor operation at the reduced
average coolant temperature. Basing on operation experience a commercial core was
developed, which is successfully operated at nuclear ships.
During the whole period of nuclear ships operation there were no cases of their preschedule
return from navigation to the port of destination because of RP failures. Though some
equipment and systems had failures including small leaks from the primary circuit into the
auxiliary circuits, there were no incidents with fission reaction control failure, uncontrolled
radioactivity distribution and respectively people overirradiation.
Qualified operation of the plant by the personnel using the hardware and parametric
diagnostics available at the ship and constant author supervision helped to reveal the failures
and malfunctions in proper time and to prevent their development and transition into the
accident beforehand. The activities directed to RP safety increase were performed in the
course of operation. For example, beginning from “Rossia” ice-breaker a new design of
compensating group drive has been used. This design provides “self-movement” and has a
step motor, developing larger forces than at the ice-breakers “Lenin”, “Arctica” and “Sibir”.
Besides all CG drives have the possibility of CG working member insertion into the core
with the help of manual drive.
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IAEA-CN-114/B-1
To provide the guaranteed reactor transfer into subcritical state a system of liquid absorber
injection into the reactor was introduced at those ice-breakers where it was absent.
At the beginning of the ice-breakers operation the design of check valves fastening in the
guide devices of the circulation primary circuit pump was improved and then they were
substituted by the modernized ones.
60 steam generators were and are operated. The results of nuclear ships RP operation have
demonstrated their reliable work. By the present time the specified lifetime and service life of
all nuclear ships steam generators except the ice-breakers “Sovetskiy Sojuz” and “Yamal”
have spent.
At the operation beyond the bounds of the specified service life there was a considerable
number of failures connected with the loss of intercircuit leak-tightness of tube system and
with the necessity to disconnect some sections.
JSC "ММP" made a decision to substitute tube systems at the ships where steam generators
had spent their specified lifetime and had a considerable number of plugged sections.
To reveal the reasons of steam generators failures in January 2002 the tube system of the icebreaker “Sibir” was cut-out and dismounted.
In 2003 the tube system of the ice-breaker “Vaigach” was substituted.
To reveal the place and the reasons of steam generator failures FSUE “Atomflot” began to
fabricate specimens made of the tube systems of the ice-breakers “Vaigach” and “Sibir”, after
it TSNII KM “Prometei” should perform laboratory investigations.
The most dangerous are the failures connected with the primary circuit leaks which happened
after the working out of the specified lifetime and were an object of special attention of the
specialists. The performed metallographic investigations of the elements cut out from the
equipment of the ice-breaker “Lenin” primary circuit and the results of the operation
conditions analysis have shown that the main factors influencing the damageability and the
residual lifetime are:
- thermocyclic loads;
- radiation effect;
- pressure increase above the allowable value.
The main reasons of the abovementioned loads are:
- unstationary RP operation modes;
- unregulated mass-exchange of cold and hot coolant with large temperature drop and small
flowrates;
- unregulated mixing of coolant flows;
- cyclic mass-exchange of hot and cold coolants, stratification of the flows in the tubes with
high temperature gradient;
- unstable SG operation at low power levels.
Due to thermocycling there were damages in the communications of pressure compensation
system, in-reactor header and the others (see fig.1). These failures became an object of
profound theoretical and experimental investigations of the equipment work at the operated
and experimental plants.
The investigation of thermocycling processes of the individual RP equipment systems
allowed the development and introduction of operation modes decreasing the damageability
of the most loaded RP units and elements at the operation beyond the bounds of the specified
lifetime at OK-900A and KLT-40 plants:
-to decrease the stresses in the elements and units of the reactor, SG and other equipment the
rate of primary coolant heating and cooling is decreased from 100ºС/hour до 20ºС/hour;
-to avoid unstable thermohydraulic operation of SG at low power levels at the primary coolant
heating feed water supply to SG in different temperature ranges is provided by special
algorithm and RP operation in power modes is provided at Nnom (15 - 100 %);
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IAEA-CN-114/B-1
-to decrease the number of cold water throws to the heated SG piping the quantity of the
circulation primary circuit pump transitions from high speed to low speed and back is limited;
-to decrease the number of CG connections and quantity of thermocycles per pressure
compensation system the rate of RP power change was lowered from
1%Nnom/s to
0,1%Nnom/s, number of power changes was decreased, the mode of interconnected control of
RP and STP was excluded, the upkeep of the average primary coolant temperature is provided
remotely in the expended limits by some definite algorithm;
-to decrease the thermocycles of the filter cooler the disconnection of purification and cooling
system is provided only at the cooled down system.
Figure 2 –Schematic diagram of the ice-breaker “Taimir” primary circuit system.
After the ice-breaker “Lenin” removal from operation there were a lot of works connected
with cutting out of the specimens and investigation of the reactor vessel material, material of
the weld between the tube system and steam generator vessel, filter cooler, circulating
primary circuit plant, circulation cool down plant, one of biological shield units and the
others.
The dominating component of the reactor vessel life duration is its radiation life time. The
activities on the irradiation and investigation of specimens materials cut out from the icebreaker “Lenin” RP reactor vessel and the additional specimens of materials of which the
other vessels of the ice-breakers reactors have been manufactured, are continued.
The correspondence of real radiational embrittlement of the reactor vessel materials to the
prediction accessments was analysed. Evaluating calculations of radiation life time of the
reactor vessels for 150000 hours and for 175000 hours were performed and primary coolant
temperatures were determined at the performance of hydraulic tests taking into account the
real content of admixtures in the reactor vessels materials.
Circulating primary circuit pump which had 130000 hours operating time was dismounted at
the ice-breaker “Arctica”, the specimens cut out from the most loaded units and details were
investigated, the units and details deterioration was analysed, the conclusions on the
subsequent circulating primary circuit pump serviceability were made.
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Primary circuit valve DN50, which had 142500 hours operating time was dismounted at the
ice-breaker “Arctika”, the specimens cut out from the most loaded units and details of the
valve were inspected and their metal investigations were performed. The results confirmed the
valve serviceability and the possibility to prolong its life time and analogous valves life time.
The reactor head, circulating cool down pump, pressure compensation system pipelines
elements of the ice-breaker “Arctika” have been revised.
2 The Practice of RP Equipment and Systems Operation Time Extension
Primarily specified life time of the replaceable RP equipment was 50- 60 thousand hours at
the service life of 20-25 years and the specified life of main equipment vessels was 100
thousand hours.
The performed investigations and inspections of the main equipment of “Lenin” (performed
after its removal from operation with the operating life of 110 thousand hours) and “Arctika”
(performed at the operating life of 143 thousand hours) ice-breakers lead to the conclusion
that there are considerable potential possibilities for the increase of the specified life time.
The inspection has shown that after 131 hours of operation the circulating primary circuit
pump remained completely serviceable. In particular there was no evident wear at the bearing
supports; electric, mechanical and hydraulic characteristics had their design values.
The same situation was with EP actuator and CG actuator drives, primary circuit valves,
circulating reactor pump, DCO-2 devices and with other RP equipment.
Metal investigations of main nozzles, of the reactor vessel metal in the area of the core, of the
weld in the bottom area did not reveal considerable changes of materials properties or any
other developing damages. It helped to develop the substantiated method of stage by stage
extension of the vessels and replaceable parts of RP systems and equipment operation time to
100000 hours without factory repair.
Operation time of the operated nuclear ships RP systems and equipment was prolonged stage
by stage by (1-1.5) thousand hours, but not more than for one navigation (~5- 6 thousand
hours) basing on positive results of examinations, inspections, calculational substantiation and
performance of repairs in accordance with the developed programs.
The results of nuclear ships operation during the prolonged period demonstrated high
reliability of RP equipment and systems, large design margins. In this connection by the
instructions of Russian government OKBM has developed “The Program of Nuclear Ships
NSSP Equipment and Systems Lifetime Extension to 150000 Hours and Service Life
Extension to 30 Years”.
Besides in 2001 close corporation "TSNIIMF" developed a common program of extension
“Nuclear Ice-breakers”. The purpose of the program was to determine the necessary efforts
for inspection, substantiation and repair of the main equipment and structures of nuclear ships
which extend their operation time.
At present OKBM and public corporation “MMP” together with other organizations and
enterprises realize the measures provided by the specified programs.
3 The Results of “The Program…” Realization
In accordance with the requirements of the specified program the following was done:
a) methods and means for nondestructive inspection of the technical state (accumulated
operation damages and defects) of the equipment and pipelines metal and welds have been
created; the accessories and inspection devices for the investigation of RP equipment
elements and pipelines have been purchased and developed;
b) complex inspection and examination of NPP systems and equipment important for safety
using nondestructive inspection methods, safety systems with the exposure of reliability
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IAEA-CN-114/B-1
indices, determination of the elements which spent their life time and should be replaced and
the elements the life time of which may be extended for some definite time, is performed;
c) acquisition and systematization of certification data on real mechanical properties of the
main and welding materials and on the deviations which took place at the fabrication of
equipment at the manufacturer plants was performed;
d) acquisition and systematization of information and the analysis of operation experience of
the systems, equipment and RP as a whole with the development of actual and predictable
models of the systems, equipment and RP is performed;
d) malfunctions and failures which took place at NPP operation are analysed and
recommendations for their exclusion during the extended period are developed;
e) metal investigations of the specimens and elements cut out of dismounted RP equipment,
valves and pipelines (vessels, removable reactor block, pressure compensation system,
circulating primary circuit pump and circulating cool down pump, filter cooler, biological
shield pipelines of "Lenin" ice-breaker, “Vaigach” and “Sibir” ice-breakers SG tube systems,
circulating primary circuit pump, reactor cover, valves, pipelines of “Arctika” ice-breaker
pressure compensation system );
ж) calculational analysis of damageability and assessment of the residual life time of RP
systems and equipment, including:
1) calculations of the defects development dynamics which were revealed after cutting
out and investigation of the details and units of RP systems and equipment;
2) calculations for the substantiation of the concept “leak before break” adaptability to
the primary circuit pipeline;
3) calculations for the residual life time substantiation.
з) safety shortage is revealed, recommendations on its removal are made, compensating
measures are proposed;
и) in addition to standard operation modes technical and organizational measures and
proposals directed to the mitigation of the influence upon RP pipelines equipment units and
elements loading are developed;
к) the programs of the life time control which allow the correcting of NPP equipment and
systems important for safety operation models are developed. In case when real operation
models considerably differ from the predicted ones the design substantiation of the
subsequent operation of RP systems and equipment will be performed and if necessary
additional recommendations and conditions for the decrease of the units loading, which limit
the life time and service life, are given.
Complex investigation of NPP and positive results of R&D performed by specially developed
“Program of the Ice-breaker “Arctika” NSSP Life Time Extension to 175 000 Hours and
Service Life Extension to 32 Years” allow the manufacturer plants the performance of some
activities including ones for safety shortage removal and the substantiation of the possibility
of RP and the ice-breaker as a whole operation time extension. In August 2003 mooring and
sea trials of the ice-breaker “Arctika” RP were performed. Basing on the results of systems
and equipment testing, including newly mounted ones it was determined that RP and its main
characteristics correspond to the design values and “The Decision on the Ice-breaker
“Arctika” RP Equipment and Systems Life Time Elongation to 175 000 Hours and Service
Life Elongation to 32 Years” was made. Renovated ice-breaker “Arctica” is the first ship
among Russian nuclear ice-breakers for which the activities on life time extension are under
performance now.
The activities on the ice-breaker “Taimir” RP service time extension have been begun. In
2003 the removable reactor block and the core which have spent its life time were substituted.
The activities on central primary circuit pump, CPS CM drives and primary circuit valves
certification were performed. By the middle of 2004 RP service life will be about 100 000
hours and the ice-breaker will return from Arctic for the performing of the other activities
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necessary for RP service life extension to 150 000 hours. The termination of activities for the
substantiation of the ice-breaker “Taimir” service life extension is planned to the 1-st quarter
of 2005.
The following ice-breakers coming to the necessity of RP service life extension are “Rossia”
(2005) and “Vaigach” (2006).
The extension of the operated and removed from operation nuclear ships life time has large
economical efficiency. By the estimation of experts real and planned expenses for the
performance of the repair (including vessel, pipeline, electrotechnical and other activities) in
the period from 2000 to 2005 for the extension of seven nuclear ice-breakers service life will
be about 1.5 billion roubles, that is about 20% of the cost of one universal two-draught
nuclear ship construction (about 280 million US dollars). The total planned service life of the
nuclear ships outside the limits of the initially specified life time will be about 55 icebreaker/years, it is equivalent to the complete service life of two newly constructed nuclear
ships. It should be also taken into account that for the designing and construction of the head
ice-breaker of new generation at the least 7-8 years are needed.
4 Conclusion
The construction of the latest to date commercial ice-breaker “50 Let Pobedy” of “Rossiya”
type will be completed not earlier than year 2005 (at the condition of enough financing). That
is why we have to talk about the coming shortage of Russian ice-breakers, which can lead to
the decrease of navigation period in Arctic.
Positive results of the activities on “The Program…” allow the extension of the operated icebreakers service life to 2015. By this time it will be possible to build the ice-breakers of new
generation which will solve the problems of freight service in Arctic and together with the
available Russian ice-breakers confirm the priority of our country in the area of nuclear civil
ship building.
7