OPERATION RESULTS ON SAFETY SYSTEMS OF TRITIUM PROCESS LABORATORY
IN JAPAN ATOMIC ENERGY RESEARCH INSTITUTE
Masayuki Yamada, Toshihiko Yamanishi, Wataru Shu, Takumi Suzuki, Hirofumi Nakamura, Yoshinori Kawamura,
Yasunori Iwai, Kazuhiro Kobayashi, Kanetsugu Isobe, and Masataka Nishi
Tritium Engineering Laboratory, Japan Atomic Energy Research Institute
Tokai, Ibaraki, 319-1195, JAPAN 81-29-282-6207
ABSTRACT
The TPL (Tritium Process Laboratory) at the JAERI
(Japan Atomic Energy Research Institute) has been the only
facility using over 1 gram of tritium for the fusion research
in Japan. The construction of the building and the safety
systems was completed until 1985. The operations of the
safety systems with tritium have been started from March
1988. The amount of tritium held at the TPL was 19.1
PBq at March 2001. The average tritium concentration in
a stream from a stack of the TPL to environment was
2.3x10-5Bq/cm3; and is 1/200 smaller than that of the
regulation value for the concentration of HTO in the air. A
record for the safety operation of tritium has thus been
accumulated. The failure data of several main components
of the TPL was also obtained giving valuable data of the
tritium operation experience.
1.
INTRODUCTION
The TPL at the JAERI was planed and was constructed
to carry out the R&D for tritium technologies (tritium
processing and tritium safety technologies) of fusion
facilities with over 1 gram of tritium. The construction of
the building of the TPL was completed in 1984; and the
construction of the safety systems was then completed in
1985. The operation of the systems were thus started from
1985 without tritium. The licensing for the tritium
handling was carried out from 1985 to 1987. The
operations of the safety systems with tritium were started
from March 1988 after the transportation of tritium to the
TPL. The TPL has been operated as the only facility using
over 1 gram of tritium for the fusion research in Japan since
19881,2.
The maximum amount of tritium permitted at the TPL
is 22.2 PBq (about 60 g), whereas the holding value of
tritium at the TPL has been in the range of 20 PBq. There
are 11 gloveboxes and 22 hoods to carry out tritium
experiments. A large amount of tritium has thus been
handled at the TPL with no accidental tritium release to
operational rooms of the TPL nor to the environment.
This paper presents the operation results of the safety
systems at the TPL for 15 years, mainly since the starting of
tritium operation (1988).
The maintenance and
improvement works for the systems are reported with the
failure data of main components at the TPL.
II. OUTLINE OF SAFETY SYSTEMS OF TPL
The concept of the safety systems at the TPL is triple
confinement as shown in Fig. 13:
(1) Air Cleanup System (ACS)
(2) Gloveboxes
(3) Glovebox Gas Purification System (GPS)
(4) Effluent Tritium Removal System (ERS)
(5) Dryer Bed Regeneration System (DRS)
The experimental apparatus, the gloveboxes (leak rate = 0.1
vol% at 100 mm Aq), and operation room (leak rate = 1
Vol% at 15 mm Aq) are designed as the primary, the
secondary and tertiary confinement. A detritiation system
is installed for each confinement.
The purpose of the ERS is to remove tritium from the
effluent gas from the experimental apparatus and gas sent
from a negative pressure control system of the glove box
(See Fig. 2). The gases from the apparatus and glove
boxes are stored in a low-pressure vessel (50-70 kPa), and
are sent to a high-pressure vessel (700 kPa) through a
compressor. The tritium in the gases is removed through
two catalytic beds at 773 K (for methane and water) and
two molecular sieve beds.
A dilution and recycle
operations are available as optional modes of the ERS (See
Fig. 3). The GPS is composed of a catalytic bed at 473 K
and the molecular sieve beds; and removes tritium in the
glove boxes by recycle operation. A main function of the
ACS is to clean up tritium released into the operation room.
The system is composed of a catalytic bed at 473 K and the
molecular sieve beds. The gases are processed by a
recycle operation (one-through mode is available.), and are
sent to a stack of TPL. The other function of the ACS is a
local exhaust system temporarily installed for maintenance
of tritium systems. The DRS carries out regeneration of
the molecular sieve beds. The tritium systems at the TPL
Negative pressure control
Operation room (tertiary confinement)
From
experimentala
Experimental
pparatus
apparatus
Configuration of safety systems at TPL
Compresser
From
glove box
Low pressure
vessel
Recycle operation of ERS
Molecular
sieve beds
Catalytic
beds
(773 K)
To stack
High pressure
vessel
Heater
Figure 2
Cooler
Conceptual flow diagram of ERS at TPL
consist of the HVAC (Heat Ventilation and Air Cooling)
system and vacuum pumping systems in addition to the
above safety systems.
An integrated operation time of the ERS with tritium was
107,700 hrs from April 1988 to March 2001, and the rate
of operation reached 94.6%. The rate of operation of the
system never reached 100% because of power cut for the
inspection of electrical apparatus at TPL. For instance,
the rate of operation for the HVAC system was 94.9%
during the same period. Figure 3 shows an amount of
tritium through each fiscal year processed by the ERS and
that released from the ERS to the stack. The ERS
received 4.6x1014 Bq (1.3 g) of tritium from April 1988 to
Amount of tritium processed
(TBq)
III. OPERATION EXPERIENCE OF SAFETY
SYSTEMS OF TPL
100
1
80
0.8
60
0.6
40
0.4
20
0.2
0
Amount of tritium released
from stack (GBq)
Figure 1
0
88 89 90 91 92 93 94 95 96 97 98 99 00
Fiscal year
Figure 3
Amount of tritium for each fiscal year
processed by ERS and that released from
ERS to stack.
1000
Amount of tritium
processed (GBq)
Amount of tritium processed (GBq)
150
100
50
100
10
1
0.1
0.01
92 93 94 95 96 97 98 99 0
0
Fiscal year
88 89 90 91 92 93 94 95 96 97 98 99 00
Fiscal year
Figure 4
Amount of tritium processed by GPS through
each fiscal year.
March 2001. The total amount of tritium released from
the ERS to the stack was 1.6x109 Bq during the same period,
where the total amount of the gas released to the stack was
21981 m3. The detritiation factor of the ERS is calculated
to be 2.8x105, which is 28 times larger than its design value.
The glove box was operated under a negative
pressure for 107739 hrs from April 1988 to March 2001
(94.6% of the rate of operation). The rate of operation of
GPS was 89.5%. Figure 4 shows an amount of tritium
processed by the GPS for each fiscal year. The GPS
received 5.1x1011 Bq of tritium from April 1988 to March
2001. The amount of tritium sent to the GPS is relatively
larger in last 4 years; this is because dismantling work on
the experimental apparatus in the gloveboxes was carried
out due to the progress of the R&D at the TPL.
The ACS was at a stand-by mode almost all the time.
The rate of operation for the stand-by mode was 92.2%.
Whereas, the integrated normal operation hours of the ACS
with tritium was 7851 hrs from April 1992 to March 2001,
and a rate of operation was 6.9%. Figure 5 shows an
amount of tritium processed by the ACS for each fiscal year.
There has been no accidental tritium release into the
operation room of the TPL; the ACS was used as the local
exhaust system for the maintenance of tritium systems
described above.
The ACS received 1.6x1011 Bq of
tritium from April 1992 to March 2001, whereas the total
amount of tritium released from the ACS to the stack was
3.7x107 Bq. A series of dismantling work on experimental
apparatus was carried out by opening the glove box in the
fiscal year of 2000, so that a relatively large amount of
tritium was processed by the ACS.
Table 1 lists the operation results of the DRS. The
molecular sieve beds have been regenerated, and all the
Figure 5
Amount of tritium for each fiscal year
processed by ACS for each fiscal year.
water produced has been stored in the TPL. Since the ERS
has processed high purity tritium from the experimental
apparatus, the tritium concentration in the regeneration
water of the ERS is much higher than that of other systems.
Table 1 Operation results of the DRS
(April 1988-March 2001)
Total amount
Average
of water
concentration of
recovered
tritium
0.11 m3
2.6 GBq/cm3
System
ERS
Number of
regeneration
12
GPS
8
0.13m3
57 MBq/cm3
ACS
45
2.66 m3
1.8 MBq/cm3
Total
65
2.90 m3
The designed detritiation factor for the tritium systems
of ITER is 100. The experience of the TPL well supported
this design value of ITER from the viewpoint of safety
operation.
IV. RESULTS OF TRITIUM WASTE FROM TPL
Three types of tritium waste, gas, water, and solid, are
discarded from the TPL. The gas waste was released from
the stack. Figure 6 shows an amount of tritium released
from the stack for each fiscal year. At the stack, molecular
species of tritium (HT and HTO) are separately measured
with a tritium monitor and a moisture corrector. The total
amount of tritium released from the stack was 11.1x10 10 Bq
(HTO) and 1.2x1010 Bq (HT) from April 1988 to March
2001. The flow rate of the gas stream at the stack is 38800
m3/h, and an average concentration of tritium at the stack
was 25 Bq/ m3. This value is 1/200 smaller than that of
the legal limit in Japan.
25
V. FAILURE DATA OF TRITIUM SYSTEMS AT TPL3
HT
20
15
HTO
10
5
0
88 89 90 91 92 93 94 95 96 97 98 99 00
Fiscal year
Amount of tritium released from stack for
each fiscal year.
Amount of tritium
released (GBq)
10000
80
1000
60
100
40
10
20
1
Amount of waste water
(m3)
Figure 6
0
88 89 90 91 92 93 94 95 96 97 98 99 00
Fiscal year
Figure 7
Amount of tritium released as waste water
for each fiscal year.
Figure 7 shows an amount of tritium released as waste
water for each fiscal year. The total amount of tritium
released as the waste water was 6.6x109 Bq (450 m3) from
April 1988 to March 2001. As mentioned above, the
regeneration water of the molecular sieve beds of the safety
systems are stored at the TPL. A cooling water system of
the TPL is a closed loop. The wastewater of the TPL is
therefore produced from tritium water experiments and
deteritiation works in the TPL.
The wastewater is
temporary stored in vessels at the TPL, and is released to a
pool of the JAERI; after its tritium concentration is
confirmed to be less than the regulation value (60 Bq/cm3).
The amount of tritium released has been still quite low level
(1/20 of that from the stack); the value increases gradually
because of the increase of the dismantling and maintenance
works of the experimental apparatus and the components of
the tritium systems at the TPL. The solid waste is also
The TPL is one of few facilities handling a large
amount of tritium for the fusion R&D in the world. The
data for operation results at the TPL is significant to design
and to evaluate the tritium systems of fusion facilities such
as ITER. For this reason, the following data has been
carefully collected and analyzed: integrated operation time;
integrated number of times of starting operation; failure
reports. Figure 8 shows the number of failure of 21 types
of components in the tritium systems at the TPL from
March 1988 to March 1999. The component types in the
figure expressed by symbols of A-Z are listed in Table 2.
Table 2 shows the frequencies of failures of components
based on the data of Fig. 8.
Nuber of failure
Amount of tritium released (GBq)
produced by the dismantling and maintenance work. The
solid waste is packed into an airtight vessel, and has been
stored in a storage yard in JAERI.
24
22
20
18
16
14
12
10
8
6
4
2
0
Number of failure due to
integrated times of operation
Number of failure due to
integrated operation hours
April 1988March 1999
December
1999
A B C D E F G H I J K LM N O P Q R S Y Z
Figure 8 Number of failure of components in
tritium systems at TPL.
In Fig. 8, the numbers of failure are due to the integrated
times of operation for valves (D, E and F), and those for
compressor (B) and sampling pump (C) are due to both the
integrated times of operation and the integrated operation
hours. For other types of components like tritium process
monitor (H) and cooling water system (O), the numbers of
failure are due to the integrated operation hours. Most of
failures were detected by either the operators checking
discrepancies or the interlock alarm of Central Control
System (CCS). For the failure caused by the integrated
times of operation, the frequency was given by the ratio of
the numbers of failure against the integrated times. In
comparison, the frequency of failure was determined by the
ratio of the number of failures against the integrated
operation hours. Both compressor (B) and sampling pump
(C) have two kinds of the frequency of failure because their
Table 2
A
Frequency of failure of components
(April 1988-March 1999)
Number
Integrated
Component
of
operation
component hours (h)
88110
Blower
5
1764*
B
Compressor
C
Sampling
pump
D
Manual valve
19
307
E
Air drive valve
49
F
Electromagnet
ic valve
62
I
Tritium room
monitor
Tritium
process
monitor
Hygrometer
J
G
H
3
Frequency
of failure
1.0x10-4/hr
0**
5417
38327*
7.4x10-4/hr
5.2x10-5**
679885
4864*
8.8x10-6/hr
3.5x10-3**
3377*
5.9x10-4**
10780*
8.3x10-4**
81840*
4.9x10-5**
7
674520
13
635079
5.9x10-6/hr
2.0x10-5/hr
9
725288
1.2x10-5/hr
Oxygen sensor
7
674520
3.0x10-6/hr
K Glovebox(GB)
10
963600
1
96360
7
636727
Master control
computer
Negative
M
pressure
control of GB
N
Preheater
L
-6
9.3x10 /hr
1.3x10-4/hr
7.9x10-6/hr
5
255629
1.2x10-5/hr
O
Cooling water
system
1
96360
P
Battery
1
96360
1.0x10-5/hr
Q
Heat contoller
3
289080
3.5x10-6/hr
R
Vacuum pump
10
67721
4.4x10-5/hr
S
Flow meter
26
2505360
1.2x10-6/hr
Y
GPS
1
75474
1.3x10-5/hr
Z
Soft ware of
computer
1
96360
1.7x10-4/hr
1.2x10-4/hr
*:Integrated number of times of
starting operation
**:Frequency of failure based on the number of times of
starting operation
failure is due to both the integrated times of operation and
the integrated operation hours. The frequency of failure
ranges from 10-5 to 10-3 for the failure caused by the
integrated times of starting operation, and from 10-6/hr
(around 10-2/year) to 10-3/hr for the failure caused by the
integrated operation hours. These data are significant to
carry out some failure analyses such as FMEA (Failure
Mode Efect Analysis) for the ITER.
VI. CONCLUSION
1) The TPL has been operated with tritium (60 g) since
1988. Experience of the technology handling a large
amount of tritium has been obtained, and no accidental
tritium release has been observed since 1988.
2) The safety systems of the TPL have usually functioned
since 1988. The detritiation factors of the systems were
20-40 times larger than the design values (102-104). The
design values for the safety systems of ITER (102) have
thus been demonstrated.
3) The average concentration of tritium in the gas from the
stack was 25 Bq/cm3 from April 1988 to March 2001,
which is less than 1/200 of regulation value in Japan.
The total amount of tritium released to environment as
wastewater (7 GBq) was 1/20 of that from the stack.
4) Some significant data for the design and evaluation of
tritium systems of fusion facilities have been obtained: the
failure frequency and life of components of the tritium
systems at the TPL; and the maintenance procedure of the
systems.
REFFERENCES
1.
2.
3.
Y. Naruse, Y. Matsuda, and K. Tanaka, “Tritium
Process Laboratory at the JAERI”, Fusion Engineering
and Design, 12, 293 (1990).
T. Hayashi and K. Okuno, “Overview of Tritium Safety
Technology at the Tritium Process Laboratory of
JAERI”, J. of Fusion Enerfy, 12, 21 (1993).
M. Yamada, M. Enoeda, T. Honma et al., “Operation
Experience on Safety System of Tritium Process
Laboratory in Japan Atomic Energy Research Institute”,
28, 1376 (1995).