添付資料 2
ワークショップの OHP 集

Impact of C-14 on the Safety Assessment ofRadioactive Waste Disposal

Oct. 27-28, 2003
Workshop on C-14 Release and Transport in Repository Environments
Wettingen, Switzerland

Osamu Tochiyama (Tohoku University)
Hiromi Tanabe, Satoru Kaneko(Radioactive Waste Management Funding and Research Center)1

Radioactive Waste Categories and Disposal Concepts in Japan
Waste
Category
廃棄物分類
Industrial waste
Waste from
nuclearpower plants

Reuse/
RecycleConcrete Debris

Operational Waste

Controlled

High-level
waste

Disposal

High-βγ Waste
Activated waste
TRU waste
Hull & End-piece

Concrete pit disposal
GroundSurface50〜100m

Low-Level Waste

Waste
containing
TRU

Controlled disposal
Trench disposal
severalmeters

Non-radioactive
waste

Very Low-Level
Waste
Decommissioning
waste

Waste from
reprocessing
plants

Disposal
Method
処分方法

Isolated
Disposal

HomoMisgeneous cellaneous
solid
solidified
waste
waste
Intermediate
depth
disposal

Over 300m

Geologicaldisposal
2

Total inventory of C-14 for each type of waste
Controlled disposal
Trench disposal

Disposal
Method
処分方法
Concrete pit disposal

Ground Surface

severalmetersC-14 Total
inventory(Bq)50〜100m

MisHomogeneous cellaneous
solid
solidified
waste
waste
Intermediate
depth
disposal
Over 300m

Geologicaldisposal

Low
level
waste

3.7E+10Highβγwaste

3.5E+15

TRU
waste

1.1E+153

Important C-14 containing TRU wastes

30-40 mmcladding hulls (zircaloy)
endpieces (SUS, Inconel)
Dose evaluation of C-14 contained in TRU wastes

4Outline of the performance assessment of TRU waste disposal
B io s p h e reRiver water scenario
・Drinking water・Crops・Stock farm products
・Marine products, etc.

EBS

NBS
Waste and Filler

BufferPore
water

Release
model

EDZ
Pore
water

Pore
water

Mixing celｌ

Diffusion

hulls, end pieces;
Congruent leaching model

Geological Media

Sorption

Sorption

Precipitation

Precipitation

Diffusion/
Advection

Sorption

Others;Mixing model①Sedimentary; Homogeneous porus model②Crystalline; Simgle fracture model

buffer (bentonite)backfillfiller (mortar)
buffer (bentonite)

structure

host
rock

waste form

Waste emplacement
area (uniform)(Waste+filler+Structure)

premise of the EBS
the EBS considered in the section of“Performance Assessment”

host
rock

Multi-barrier concept of
TRU waste disposal

5Transport parameters for the assessment
base dataoxide film
inventory matrix without oxidefilmvariation data

1.3E+14 Bq
4.9E+14 Bq
referencecase1)

constant
release2)

decreasing
release2)oxide film

instant release

400 y200,000 y

matrix without oxide
film

7600 y22,000 y

6.8E+8 yhydraulic conductivity for NBS

1E-9 m/s

1E-10 m/s, 1E-8 m/s, 1E-7 m/s

distribution coefficient of C-14
for cement and rock

0.1 ml/g

10 mg/l, 100 ml/g, 500 ml/g

leaching
period1) 「Progress Report on Disposal Concept for TRU Waste in Japan」2000.3
62) 「A Study on Chemical Forms and Migration Behavior of Radionuclide in Hull Waste」ICEM’99

C-14 leaching rate of each case
1E+03

Reference case(oxide film),(instanse release)

1E+02
1E+01
1E+00

Constant release case(oxide film)，(400y)
Reference case
Hull (without oxide film) ，(7600y)leaching rate [mol/y]

1E-01

Constant release case
Hull (without oxide film)，(22,000y)

1E-02
1E-03

Decreasing release case(oxide film)，(200,000y)

1E-04
1E-05
1E-06
1E-07
1E-08
1E+00

Reference case
Constant release case
Decreasing release case

1E+01

1E+02

1E+03
time [y]

1E+04

1E+05

1E+06

7

Dose evaluation of the case considering the variationof rock hydraulic conductivity and leaching period (1/2）- oxide film 1E-04

Rock hydraulic conductivity : 1E-9m/s
Kd = 0.1 ml/g

1E-04

Rock hydraulic conductivity : 1E-10m/s
Kd = 0.1 ml/g

1E-05

1E-05

1E-06

dose rate [Sv/y]dose rate [Sv/y]dose equivalent limit for exempt wastes or shallow underground disposal
Reference case(instant release)

1E-07

Constant release case (400y)
1E-08

Decreasing release case(200,000y)

1E-06

Constant release case (400y)
1E-08

Decreasing release case(200,000y)

1E-09

1E-09

1E-10
1E+00

1E-10
1E+00

1E+01

1E+02

1E+03

time [y]Reference case(instant release)

1E-07

1E+04

1E+05

1E+06

1E+01

1E+02

1E+03

1E+04

1E+05

time [y]oxide film: K < 1E-9 m/s → dose << 10 µSv/y

8

1E+06

Dose evaluation of the case considering the variationof rock hydraulic conductivity and leaching period (2/2）- oxide film Rock hydraulic conductivity : 1E-8m/s

1E-04

Rock hydraulic conductivity : 1E-7m/s

1E-04

Kd = 0.1 ml/g

Kd = 0.1 ml/g

Reference case (instant release)
1E-05

Constant release case(400y)

Reference case(instant release)

1E-06

dose rate [Sv/y]dose rate [Sv/y]

1E-05

Constant release case (400y)
1E-07

Decreasing release case(200,000y)

1E-08

1E-06

Decreasing release case(200,000y)
1E-07

1E-08

1E-09

1E-09

1E-10
1E+00

1E-10
1E+00

1E+01

1E+02

1E+03

1E+04

1E+05

1E+06

1E+01

1E+02

time [y]oxide film: K ≥ 1E-7 m/s → dose > 10 µSv/y

1E+03

1E+04

1E+05

time [y]91E+06

Dose evaluation of the case considering the variationof rock hydraulic conductivity and leaching period (1/2）- matrix without oxide film 1E-04

1E-04

Rock hydraulic conductivity : 1E-9m/s

Rock hydraulic conductivity : 1E-10m/s

Kd = 0.1 ml/g

Kd = 0.1 ml/g
1E-05

1E-06

1E-07

dose rate [Sv/y]dose rate [Sv/y]

1E-05

Reference case
(7600y)Constant release case
(22,000y)

1E-08

1E-09

1E-10
1E+00

Decreasing release case
(6.8E+8y)

1E+01

1E+02

1E+03

time [y]1E-06

Reference case
(7600y)1E-07

Constant release case
(22,000y)

1E-08

1E-09

Decreasing release case
(6.8E+8y)
1E+04

1E+05

1E+06

1E-10
1E+00

1E+01

1E+02

1E+03

1E+04

1E+05

time [y]matrix: K < 1E-9 m/s → dose << 10 µSv/y

10

1E+06

Dose evaluation of the case considering the variationof rock hydraulic conductivity and leaching period (2/2）- matrix without oxide film 1E-04

1E-04

Rock hydraulic conductivity : 1E-7m/s

Rock hydraulic conductivity : 1E-8m/s
1E-05

1E-05

Constant release case
(22,000y)

1E-06

1E-07

Reference case
(7600y)1E-06
dose rate [Sv/y]dose rate [Sv/y]Reference case (7600y)

Constant release case
(22,000y)

1E-08

1E-07

Decreasing release case
(6.8E+8y)

1E-08

Decreasing release case
(6.8E+8y)
1E-09

1E-10
1E+00

1E-09

1E+01

1E+02

1E+03

1E+04

1E+05

1E+06

1E-10
1E+00

1E+01

1E+02

time [y]matrix: K ≥ 1E-7 m/s → dose ≅ 10 µSv/y

1E+03

1E+04

1E+05

ｔｉｍｅ [y]

11

1E+06

Dose evaluation of the case considering the variationof rock hydraulic conductivity and leaching period- oxide film plus matrix 1E-04

1E-04

Rock hydraulic conductivity : 1E-10m/s

1E-05

1E-05

1E-06

1E-06

dose rate [Sv/y]dose rate [Sv/y]Rock hydraulic conductivity : 1E-9m/s

Reference case 01
Constant release
case02

1E-07

1E-08

Decreasing release case03

Reference case 10
1E-07

Constant release
case11
1E-08

Decreasing releasecase 12

1E-09

1E-09

1E-10
1E+00

1E-10
1E+00

1E+01

1E+02

1E+03

time [y]

1E+04

1E+05

1E+06

1E+01

1E+02

1E+03

1E+04

1E+05

time [y]oxide film + matrix: K < 1E-9 m/s → dose << 10 µSv/y

12

1E+06

Dose evaluation of the case considering the variationof rock hydraulic conductivity and leaching period (2/2）- oxide film plus matrix 1E-04

1E-04

Rock hydraulic conductivity : 1E-7m/s
Reference case 04

Rock hydraulic conductivity : 1E-8m/s
1E-05

1E-05

1E-06

1E-07

Constant release
case05Constant release
case08dose rate [Sv/y]dose rate [Sv/y]Reference case 07

Decreasing releasecase 09

1E-08

1E-09

1E-10
1E+00

1E-06

Decreasing releasecase 06

1E-07

1E-08

1E-09

1E+01

1E+02

1E+03

time [y]

1E+04

1E+05

1E+06

1E-10
1E+00

1E+01

1E+02

1E+03

1E+04

1E+05

time [y]oxide film + matrix: K ≥ 1E-7 m/s → dose > 10 µSv/y

13

1E+06

Dose evaluation of the case considering the variationof distribution coefficient for cement- oxide film plus matrix 1E-04

Rock hydraulic conductivity : 1E-9m/s

1E-04

Rock hydraulic conductivity : 1E-7m/s
leaching period : reference caseleaching period: reference case
1E-05

Reference case 04
Kd : 0.1ｍｌ/g

1E-05

Reference case 01
Kd : 0.1ｍｌ/g

1E-06

1E-07

dose rate [Sv/y]dose rate [Sv/y]Reference case 16
Kd : 10ｍｌ/g

Reference case 13
Kd : 10ｍｌ/g
Reference case 14
Kd : 100ｍｌ/g

1E-08

1E-06

1E-07

Reference case 17
Kd : 100ｍｌ/g
Reference case 18
Kd : 500ｍｌ/g

1E-08

Reference case 15
Kd :500ｍｌ/g
1E-09

1E-10
1E+00

1E-09

1E+01

1E+02

1E+03

time [y]

1E+04

1E+05

1E+06

1E-10
1E+00

1E+01

1E+02

1E+03

1E+04

1E+05

1E+06

time [y]Kd : 0.1 ml/g → higher → dose → lower

14

Dose evaluation of each case (Sv/y)- oxide film plus matrix Leaching period (years)
Hull
Hull
(without(oxide film)oxide film)
case01 Instant release
7,600

Rock hydraulicconductivity for
NBS
(m/s)

Distribution
coefficient for
Cement(C-14)(m/g)(ml/g)

1.00E-09

Allradionuclide(Sv/y)

C-14(Sv/y)

1.9E-07

1.7E-07

1.0E-07

9.2E-08

case02400

22,000

case03200,000

6.80E+08

1.1E-08

7.9E-09

case04 Instant release

7,600

1.9E-05

1.8E-05

case05400

22,0001.6E-05

1.5E-05

case06200,000

6.80E+08

9.4E-078.2E-07

2.2E-06

2.1E-06

1.2E-06

1.2E-06

1.00E-07
Base data
0.1

case07 Instant release

7,600

case08400

22,000

case09200,000

6.80E+08

1.2E-07

1.0E-07

case10 Instant release

7,600

9.1E-08

8.2E-08

case11400

22,0005.1E-08

4.5E-08

case12200,000

6.80E+08

5.7E-09

3.8E-0910

9.7E-08

7.8E-08100

3.4E-08

1.3E-08500

2.5E-08

2.7E-09

1.00E-08

1.00E-10

case13
case14 Instant release
case157,600

1.00E-09＊）■：Reference case , ■：Constant release case , ■：Decreasing release case

15

Conclusion
1. C-14 is one of the dominant nuclide affecting dose from TRU orhigh βγ wastes.
2. Safe disposal of C-14 containing waste is expected to be
applicable for a wide range of geological condition in Japan, evenwhen the target dose constraint is set to 10 µSv/y.
3. Fairly inferior geological condition (hydraulic conductivity > 10-7m/s) may give the resultant dose higher than 10 µSv/y.
4. The above disadvantage can be overcome when we can set morefavorable values for other parameters (leaching rates,
distribution coefficients) by knowing the mechanism controllingthese parameters.
5. Researches for more reliable migration data and more realistictransport models of C-14 are necessary for the safe disposal ofradioactive wastes.
16

Behaviour of 14C in the Opalinus Clay
Safety Case
L.H. Johnson and B. Schwyn
Workshop on C-14 Release and Transport in
Repository Environments
October 27 - 28, 2003
Wettingen, Switzerland

2004/8/12

1

C-14 Workshop

Scope• Background on the Opalinus Clay study• Waste Types and EBS• Assumptions regarding chemical form of 14C in different
waste types (SF, HLW and ILW)

• Release of 14C from the various wastes• Treatment of solubility and sorption of released 14C• Results of various transport calculations• Summary and research needs

2004/8/12

2

C-14 Workshop

Repository in Opalinus Clay

2004/8/12

3

C-14 Workshop

Geological sequence at Benken and isolation concept

Repository depth - 650 m
Thickness of Opalinus Clay - 100 to
130 m
Hydraulic conductivity - 2 x 10-14 m/s

2004/8/12

4

C-14 WorkshopSF and HLW canisters

2004/8/12

5

C-14 Workshop

ILW containers and emplacement geometry

LC2-MA-25

Emplacement containers for ILW

WA-BNF-2 /7

WA-BNF- 4

LC2-MA-20

WA-COG-2

WA-COG-4/6

20

2400

2438

20

20

2000

2438

WA-COG- 6

252438

2004/8/12

6

C-14 Workshop

25

25

2438

Assumptions regarding chemical form and release of 14C from SF and HLW• Spent fuel• Oxide matrix - Concentration of 25 ppm N is assumed for calculations of
14C inventory. Chemical state uncertain (oxycarbide?) and 14C is assumed

to be released in inorganic form. Rapid release of 10 % is pessimisticallyassumed based on U.S. and Canadian leaching data.

• Zircaloy - 80 ppm N assumed for calculations of 14C inventory. Chemical
state of 14C is probably carbide, leading to release of organic 14C upon
corrosion. Rapid release of 20 % of 14C in Zircaloy is assumed.
Remainder is released slowly as Zircaloy corrodes (10 nm/a).

• Steel and Ni-alloy assembly components - up to 800 ppm N present• HLW• 14C inventory about 1000x lower than for SF. Assumed to be inorganic,
with no instant release fraction

2004/8/12

7

C-14 Workshop

Release of 14C from SF
14

10

C Release from Used CANDU Fuel

1

10 0

No relationship to fission gas
release (C form is non-volatile)

Avg 2.7 +/- 1.6

Stroes-Gascoyne et al. 1994

10 -1

14

C Release (% Total Inventory)

Releases range from 1 to 6 %Xe GapXe Gap + Grain Boundary

10 -2
10 -2

10 -1

10 0

Stable Xe Release (% Total Inventory)
2004/8/12

8

C-14 Workshop

10 1

Assumptions regarding chemical form and release of 14C from ILW• Variety of reprocessing waste types from BNFL and COGEMA• About half of the 14C in the wastes is assumed to be organic(principally that present in Zircaloy hulls and ends wastes).

• In the release model, all of the 14C in all waste types is assumed
to be released 100 years after repository closure, i.e. no credit
for the corrosion resistance of any of the wastes.

2004/8/12

9

C-14 Workshop

Retention processes considered in safety assessment

2004/8/12

10

C-14 Workshop

Diffusion of 14C through bentonite and Opalinus Clay
Opalinus Clay"Kd" of 14Cinorg:
0.001 m3 kg-1
Kd of 14Corg = 0• Inorganic 14C• Isotopic dilution with 0.27% of
the calcite present• Transformed into a pseudo
sorption value "Kd"

• Opalinus Clay
CaCO3:[CO3]porewater:

16 wt.%
2.7 mol m-3• Bentonite

Bentonite"Kd" of 14Cinorg:
6 × 10-5 m3 kg-1
Kd of 14Corg = 0

CaCO3:[CO3]porewater:

0.7 wt.%
2.8 mol m-3• Organic 14C• No retention assigned becauseof unknown structure

2004/8/12

11

C-14 Workshop

Sorption of 14C in cementitious ILW tunnel

O p a lin u s C la y
"K d " o f 1 4 C in o rg :0 .0 0 1 m 3 k g -1
K d o f 1 4 C o rg = 0

C o -p re c ip ita tio n o f
14
C in o rg w ith C a C O 3 a t
th e in te rfa c e ?

• Inorganic 14C• Isotopic dilution with 1% of thecalcite present in cement• Expressed as shared solubility
1% of CaCO3 in cement:
4 × 10-4 mol kg-1
[CO3]porewater:

IL W tu n n e l
m ix in g ta n k

C em ent
14

C in o rg :s h a re d s o lu b ility
K d o f 1 4 C o rg = 0

2004/8/12

12

C-14 Workshop

2 × 10-4 mol L-1• Organic 14C• No retention assigned because of
unknown structureKey results
SF

Deterministic analyses
Reference Case results
SF - Main dose contributors are 129I
36Cl, 14C (org) and 79Se
HLW - Main dose contributors are
129I, 36Cl and 79Se
ILW - Main dose contributors are
129I, 36Cl, 14C (org) and 79Se

HLW

Max. doses are ~100x below
regulatory limit

ILW

2004/8/12

13

C-14 Workshop

Release of radionuclides from ILW - reference case2004/8/12

14

C-14 Workshop

Organisation of assessment cases
Scenarios
Reference Scenario - Releaseof RN's in solution throughhost rockRelease of volatile 14C alonggas pathway
RN release affected byhuman action'What if?' cases (no scientificbasis but to test systemrobustness)

System options
Biosphere uncertainty
2004/8/12

15

C-14 Workshop

Conceptualisations Parameters
Diffusion & advection
NF alternatives
Geo alternatives
Role of access tunnels
Gas & convergence effects
Through host rockAffected by accessseveral sets
several sets
several sets
several sets
several sets
several sets
several setsborehole (near hit, direct hit)
abstraction deep groundwaterabandoned repository
high water flow
discontinuities with flow
several phenomena
gas- induced
instantaneous release volatile
14
C
poor NF/Geo/flow
more wastes
other ILW waste form
SF canister
alternative geomorphologies
alternative climates

several sets
several sets
several sets
several sets
several sets
several sets
several sets
several sets

several sets

Assessment case for instantaneous transport of 14C
It is assumed that 14C that is released in organic form
from SF or ILW can be converted to a volatile form (e.g.
methane) and be transported with H2 formed bycorrosion. Transport through the Opalinus Clay is
assumed to be instantaneous. The case is hypotheticaland meant to illustrate the robustness of the systemwith respect to uncertainties.
The results show that doses would be similar to thereference case.

2004/8/12

16

C-14 Workshop

Summary• Conservative assumptions regarding 14C release andtransport lead to organic 14C being one of the main dose
contributors in calculations.

• Because of its relatively short half-life, any significant
sorption would eliminate the dose contribution in Opalinus
Clay host rock.

• It is clearly important to gain an improved understanding of
the chemical form of released 14C and its sorption
characterisitics.

• By inference, the need for better data on 14C behaviour ismore important for host rocks with a confinement capacitythat is lower than that of Opalinus Clay.

2004/8/12

17

C-14 WorkshopThe Study for The Chemical Forms of
C-14 Released from Activated Metals
October 27-28, 2003
JNFL
RWMC
MHI
NDC
TOSHIBAContents
1. Objective
2. Experimental Procedure
3. The Results of Ｌｅａｃｈｉｎｇ Test (No.1)
4. The Results of Leaching Test (No.2〜7)
5. Discussion
6. Conclusion
7. Summary1１．Objective• The distribution coefficients of C-14 for barrier materials, e.g.
cement, bentonite and so on, would be low, if the form of C-14 ismainly organic. The distribution coefficient for C-14 released
from activated metal would depend on the chemical form
• In this study, the chemical forms of C-14 released from activatedmetals at a disposal site were investigated.
Bentonite

Waste

Backfill

Chemical form：influences to flow rate of
C-14, and Kd-values
Refer to the distributionof C-14

Release Rate：Dependent on Corrosion Rate of Material
Refer to the Distribution of C-14

2

２．Procedure (Material)

Investigation on chemical forms：activated stainless steel
Investigation on generation of carbon compounds from somematerials：Fe3C、ZrC etc
No.

Material

Carbon in Metal
CarbideSolute1

Activated Stainless Steel

△*

2
3

Ｆｅ３Ｃ

Pearlite○○

4
5

Carbon Steel

○

6
7

ＺｒＣ
Ｚｒ

Martensite○△○*
Carbon 1wt%△○

Carbon １wt％△
* The part of C-14 nuclides generated byneutron activation of N-14 would becarbide.
3

CarbideSolute２．Procedure (Conditions etc)
① Materials

7 materials including activated sample② Atmosphere Anaerobic alkaline condition③ pH

pH12〜pH８④ LeachingTime

１〜15 months⑤ Analytical
MethodActivated Sample ：high performanceliquid chromatography+ liquid scintillation analyzer
Cold Samples：high performance liquid
chromatography or GC-MS
4

2．Experimental Method (Objects for Detection)

Gas Phase ・The concentration ratio of
each organic compound ingas phase
Liquid Phase・The concentration ratio
for TOC in total carbon in
the solution
・The concentration ratio of
each organic compounds in
the TOC in the solution
5

３．The Results of Ｌｅａｃｈｉｎｇ Test(No.1) (1/2)
・The ratio of organic and inorganic C-14 in gas and liquid
phase

Material

Org. in Gas
Phase
LiquidActivated
Stainless SteelNot Measured

Org.

66〜75%

Phase Inorg.

25〜34%

6

３． The Results of Ｌｅａｃｈｉｎｇ Test(No.1) (2/2)
・Organic carbon in liquid phaseNo.

1Material

Activated
StainlessSteel

The ratio of organic carbon compounds in liquid phase （％）

pH *

10

FormicAcid

AceticAcid

Acetaldehyde

Formaldehyde

Metha
nol

Ethanol

PropanolUnknown

10

43

N.D

9

10

6

N.D

22

● The concentration ratio for TOC in total carbon in

the solution is 66%〜75%* pH１０ Simulated Groundwater

7４．The Results of Leaching Test (No.2〜7)(1/2)
・The ratio of organic/inorganiccarbon in liquid and gas phase

Solid

Carbon
Steel

Zr

Fe3C

ZrC

Carbon in Each Phase

Organics in Gas Phase〜0.01%

Not
Not〜0.01% Measured Measured

70〜85%

55〜85% 55〜65%

88〜90%

Inorganic 15〜30%

15〜45% 35〜45%

10〜12%(Organics)
Carbon in
Liquid Phase

Organics

8

４．The Results of Leaching Test (No.2〜7)(2/2)
・The ratio of each organic carbon compound in the liquid phase
Solid

pH for thesolution *The Ratio of Organic Carbon Compounds For Liquid Phase （％）
FormicAcid

AceticAcid

Acetaldehyde

Formaldehyde

Metha
nol

Etha
nol

Propa
nol

Unknown

8

51

49

N.D

N.D

N.D

N.D

N.D

−

12.5

52

48

N.D

N.D

N.D

N.D

N.D

−

Pearlite

10

23

77

D

D

D

D

N.D

−

Carbon
Steel

8

36

45

N.D

12

N.D

7

N.D

−

12.5

20

71

N.D

6

N.D

3

N.D

−

Martensite

10

14

26

9

N.D

12

33

6

−

ＺｒＣ

8

3

97

N.D

N.D

N.D

N.D

N.D

−

12.5

6

94

N.D

N.D

N.D

N.D

N.D

−

8

17

33

N.D

20

N.D

30

N.D

−

12.5

9

56

N.D

16

3

16

N.D

−

Ｆｅ３Ｃ

Ｚｒ

• pH１０ Simulated Groundwater 、pH8and pH12.5:sodium hydroxide Solution• D：Detected Slightly

ND: Not Detected9５．Conclusion (1/2)
〈Gas Phase〉
・ The experiments with cold samples (No.2 〜7) indicate a slight
concentration of organic carbon in gas phase.

〈Liquid Phase〉
・ The experiments with hot samples (No.1) indicate the ratio of organic C-14
released from activated metal in liquid phase is 66〜75% (The ratio for
inorganic C-14 is 23〜34%).
・ From carbides and non- activated metals→Generated organic carbon compounds might be not only carboxylic acid but
also alcohols owing to increasing the ratio of solute carbon in metallic
phase→The ratio of acetic acid concentration from ZrC is higher than that from
Fe3C.
10

５． Conclusion (2/2)• The organic compounds of each material
Material

pＨ

The ratio of each organic compound

Fe3C

12.5

100

Pearlite

10

100

Carbon Steel

12.5

91

Activated
Stainless10

Martensite

10

ZrC

12.5

Zr

12.5

53

6 3

9

40

9

16

22

51
100

0%

10%

Carboxylic

20%

30%

Aldehyde40%

Alcohol

19

16
17

65

50%

60%

70%

80%

90%

100%

unknown

There are no differences in the kinds of organic carbon from the metals.

11

６．Discussion (1/2)
The chemical forms released from metals would be
dependent on the chemical condition in the metallic
phase.
① Generated organic carbon compounds might becarboxylic acid for carbides（hydrolysis for
carbides）.
②Generated organic carbon compounds might be
not only carboxylic acid but also alcohols owing
to increasing the ratio of solute carbon inmetallic phase（Fischer-Tropsch reaction）.
12

６．Discussion (2/2)
①

+
2OH →

H
H

C

C

H

OH

O

② CO＋（2n+1）H2 → CnH2n+2 ＋ nH2O
⇒CO+2H2→CH3OH････ Fischer-Tropsch Reaction 13

７．Summary
・The ratio for organic C-14 released from activated metal in liquid phase is 66〜
75% (The ratio for inorganic C-14 is 23〜34%).There is slight concentrationof organic carbon in gas phase from carbides and non- activated metals.
・ Generated organic carbon compounds might be carboxylic acids for carbides.
Increasing the ratio of solute carbon in metallic phase would cause thegeneration of not only carboxylic acid but also alcohols .
・There are no differences in the kinds of organic carbon from the metals.
・Future Study
The investigation on generation of organic forms of C-14 from activated metals
i.e.. The leaching experiment for activated Zirconium alloy or non-activatedstainless steel.

14

Methods for measuring 14C on
spent ion exchange resins – a review
Kristina Stenström and Åsa Magnusson
Div of Nuclear Physics
Lund University, Sweden

14C in reactor coolant

BWR: mainly 14CO2/carbonates
PWR: mainly CO, hydrocarbons (formaldehyde,
formic acid, acetaldehyde, methanol, ethanol,
acetone and acetic acid)
14C on ion exchange resins

Many different opinions in the literature…
Varying results…
14C needs to be measured!

Acid stripping
Author (year)
Aitolla and Olsson (1980)

carbonateorganic

Combustion
speciation

total

X

X

X

Speranzini and Buckley (1981)
Nott (1982)

X

Salonen/Snellman (1981-1985)

X

X

Bleier (1983)

X

Martin (1986)

X

Chang et al (1989)

X

Martin et al (1993)

X

X

Moir et al (1994)

X

X

Vance et al (1995)

X

X

Supercritical fluid extraction – Dias and Krasznai (1996)
Microbial treatment (total 14C) – Tusa (1989)

X

Acid stripping in generalGasflow inGas
flow out

IX sample(a few g)
PurifierCO+ carrier2+ acidAeratedMagnetic stirring
Ultrasonic probe
Flowing acid
etc…

CO2
Absorbtion(NaOH orLSC cocktail)

Water trap
Ice trap
HCl trap
etc…

LSC>1 trap
Various designs

Aittola and Olsson (1980)
30 mlkonc. HCl
Air

Water
trap
Resin sample (~4 mg)
1. Na2CO3
2. NaHCO3+NaOH•••

2×250 ml 5M
NaOH

30 ml
saturated
Ca(OH)2

Recovery (14C-labelled standard) :1) 33%-49% 2) 85%
Precipitate as BaCO3 (modified in test 2))
No info about reproducibility, interference ormemory effectStrippingcolumn withresin

Nott (1982)

Acid
pump

Spray trap

Air
inlet

Ultrasonicprobe andgenerator

HCl (2.0-3.0 M)
magnetic stirring

VacuumPump

Exhaustto fumehood

0.5-2.0 M NaOH Fritted glass disc(first two 250 ml; third
150 ml)•Recovery: Range (91.8 - 102.1)% Mean (97.4 ± 3.6)%•No info about memory effect•Potential problem of interfering radionuclides

Salonen/Snellman (1981, 1982, 1985)
Molecular
sieve
Flow
meter

Silicagel

6M HCl
CuO-catalyzer at 800 °C

Flow
meter

Air
bottleSample vial
2M
SafetyNaOHNaOH flask
NaHCO3 carrier(NaOH)
Magnetic stirring

•
•
•
•
•
•
•

2M
NaOH

Recovery: 93% with minor variations
Precipitate as BaCO3
No memory effectNo interference from other radionuclides
Catalyst efficiency?
CO/hydrocarbons are easily lost
Drying the resin evaporates 14C

Safetyflask(NaOH)Pump

SDEC-FranceChang et al (1989)(HCl, NaCl, Na2CO3 or
NaOH)
Air

VacuumPump

Batch reactor withmagnetic stirring

Water trap
(5% HCl)

2 M NaOH
traps•Best results with aerated agitated HCl•Recovery: (98.5-100)%•No interfering radionuclides in the NaOH (but in watertrap) and no memory effect•Real samples: remaining 0.5% removed with K2S2O8

Combustion in generalGasflow in
IX sample(a few g)infurnace
Oxygen, air
Catalyst
Various tempGasflow out

Purifier

CO2
Absorbtion(NaOH orLSC cocktail)

Water trap
Ice trap
HCl trap
etc…

LSC>1 trap
Various designs

Speranzini and Buckley (1981)
Furnace(400-900 ºC)

Stainlesssteel tube

CuO-catalyzer
at 250 °C

Air
VacuumPump

Ceramic
boat
Cooling water

Condenser HCl trap
(1 M, 100 ml)

NaOH traps(2 M, 100 ml)•Recovery: (93-98)%•Ion exchanged carbonates are not thermally stable:
CaCO3 + SO2 + ½ O2 → CaSO4 + CO2
Reaction rate increases in the presence of CaCl2

Martin et al (1993): Combustion
Electric tube
furnaceAir

Pt on Al andCuO
wire catalysts

0.5 g
sample ina nickelboat

Vacuum
valve

Flow
meter

Ice trapsGas
dryingtube

Bubblers filled withcarbon-specific LSC
cocktail•740 °C for 30 minutes•Recovery: (63±9)%•Not clear how well optimized

To vacuumMartin et al (1993): Acid stripping
Room airand acid orbase

Vacuumcontrol valve

To vacuum
Flow
meter

Flask and bubbler
containing resin sample

Bubblers filledwithcarbon-specific
LSC cocktail•Recovery: (85±7)% (combustion (63±9)%)•No memory effect•60Co does not interfere

Moir et al (1994)•Anion/cation separation by a sugar solution•Parr bomb combustion for total 14C•Acid stripping for 14C/carbonates•Recoveries:
acid stripping (93±5)%
Parr bomb combustion (100±10)%•No cross-contamination or memory effect•Sugar separation ⇒ microbial activity?

Vance et al (1995)
Acid stripping (inorganic 14C)
6 M H2SO4
purification traps
Ca(OH)2/methanol trap
purification of CaCO3 precipitate
Combustion (total 14C)

No information about recovery etc.

What do we want to do?
•

Organic/inorganic fraction

Author (year)

Acid regeneration
carbonate

Aitolla and Olsson (1980)

organic

Combustion
speciation

total

X

X

X

Speranzini and Buckley (1981)
Nott (1982)

X

Salonen/Snellman (1981-1985)

X

Bleier (1983)

X
X

Martin (1986)

X

X

Chang et al (1989)

X

Martin et al (1993)

X

X

Moir et al (1994)

X

X

Vance et al (1995)

X

XStudy on Photocatalytic Decomposition ofOrganic C-14
in Waste Packages
October 27-28, 2003
RWMC
(Radioactive Waste Management Funding and Research Center)

Kobe Steel, Ltd.
1

1. Expected Performance and Tasks of Waste Packages

Characteristics of organic C-14

Barrier of waste packages

・Long half-life (5730 years)●Corrosion resistance・Low adsorption to clay, rock●Restriction of water permeability/nuclide release・Low propensity to precipitate
Barrier of infilling material●Decomposition oforganic C-14 by photocatalysts

Difficult to reduce organic C-14
release by present barriermaterials

Improvement of distribution
coefficient by decomposition＜Objectives of this study＞
・ Evaluation of corrosion resistance of package material (local corrosion, bending/welding parts)◎ Evaluation of photocatalytic effect for decomposition of organic C-142

(1) Reactions on Photocatalysts
TiO
2 Particle
TiO2粒子
-ray
β線

CH3OH

H2O

h+
e-

CH3OH
・OH CH3OH
・O2CO2
H2O
O2

Valence
Band

Band Gap of TiO2

γ線
-ray

Schematic model of photoelectrochemical reactions
TiO2+hνÆ TiO2+ e-+h+
Reduction

Oxidation① e-+O2Æ・O2-(Aerated)② 2e-+2H2OÆH2+2OH-(Deaerated)

Conduction Band① h++H2OÆ・OH+H+② h+Æhtrap+

Potential-pH equilibrium diagram
ｆor the system carbon-water at 25℃

3

(2) Application of Photocatalysts to Waste Packages

Infill photocatalysts in waste packages

Repository

Photocatalytic decomposition

Waste Packagesof organic C-14

Retention of C-14 by sorption(Improve Distribution Coefficient)

CH3OH

Photocatalysts

Improve barrier performance
Waste Package

by infilling4(3) Studies with UV
Decomposition test of methanol by TiO2 with UV
Decomposition rate [%]30
TiO2 (100 ppm)
TiO2 (1000 ppm)
Fe2O3, MnO2, V2O5

25
20
15

1) TiO2 can decompose methanol.

UV energy：8000-10000 mW/m2
UV source：black light
Wave length：360 nm

10
5
0
0

5

10
15
Time [hr]25

UV Source：Black light
Wave length：360 nm

3) TiO2 can act with low energy
UV.
Æ Improved Quantum efficiency

100

After 10,000 years

Decompositon rate [ppm/20hr]

UV Source：D2, Xe lamp
Wave length：360 nm

202) The decomposition proceedswith time.

10
1
0.1
0.01

Linearization

Possibility of photocatalysts
with low energy radiation

0.001
0.1

1

10
UV energy

100
1000[mW/m2]

10000

5

(4) C-14 in Waste Packages<Dimensions>
Disposal
5.0E+11 Bq

Waste package:1.4 x 1.4 x 1.4 m
Canister:φ0.43 x 1.34 mH x 9Canister x 9

C-14 inventory
in a canister
5.5E+10 Bq/canister*1)

C-14 Inventory [Bq/package]

6.0E+11After 1,000 years
4.4E+11 Bq

5.0E+11
4.0E+11After 10,000 years
1.5E+11 Bq

3.0E+112.0E+11
1.0E+110.0E+00(1) C-14 in oxide film: 20%*2)

Compressed hull waste
Leach immediately(2) C-14 in base material: 80%

Leach with corrosion gradually（image sample）

0

2,000

4,000

6,000

8,000

10,00012,000Time [year]

C-14 concentrationin waste package
10-5 mol/L order*3)*1) RWMC, Development of radioactive wastes treatment system (1998).
*2) Noma et al., Study for TRU waste disposal system (2000).
*3) Specific activity of C-14: 2.31TBq/mol, filling factor of packages: 60%．

6

2. Objectives- Photocatalysts oxidize organics by converting
photon energy to electro-chemical energy.
- Activation of photocatalysts by γ- rays has
been reported.
1) Activation by low energy radiation in repository conditions
2) Decomposition of suggested organic matters

Evaluate technical possibility of
Decomposition of organic C-14 byphotocatalysts with β- rays
7

3. Materials- Photocatalysts :Anatase TiO2 sintered on titanium plate (Kobe Steel,ltd.)high photoactivity, stable physically and chemically- Organic matters :A: 12.7
B: 8.0

A: 0.7
B: 0.5

C-14 labeled Methanol (ICN Biochemicals)20

C-14 labeled Formaldehyde (ICN Biochemicals)
C-14 labeled Formic Acid (American radiolabeled chemicals)
Micro grooves on
surface

Cross section

Crystal structure(<100 nm)TiO2 surface

TiO2 layer

Titanium84. Methods
Prepare test solution

Install photocatalysts and test solution

Seal glass vials
Photocatalyst

Place in container for shielding

β- ray irradiation

Container for shielding9

5. Conditions(1) Temp: Room temperature(2) Solution pH: pH11 (NaOH)(3) Organic matters: Methanol
Formaldehyde
Formic acid(4) Radioactive concentration: 25 MBq/L(5) Organics concentration: 1.2 - 1.4×10-5 mol/L(6) Surface area/water volume : 1.27 cm2/ml(7) Irradiation time

: 10, 20, 40, 80 days

(8) Analysis: Radioactive concentration（Liquid Scintillation Counter）
106. Procedure for Analysis
Decomposition of organics by photocatalyst

Decomposition products (14CO32+) in solution
Separate 14CO32+ (carbonate precipitation)

Deposit (inorganic C-14)

Filtrate (organic C-14)

LSC

LSC

Evaluate decomposition of organic C-14
11

7. Results - Methanol

Radioactive consentration [MBq/L]

Variation of CR (radioactive concentration) in methanol solution
30
Total C-14 (w/ TiO2)

25
20

Organic C-14 (w/ TiO2)

15

Inorganic C-14 (w/ TiO2)

10

Total C-14 (w/o TiO2)

5
0
0

10

20

30 40 50
Time [day]

60

70

80

- CR of inorganic C-14 increased.（decomposition rate: 20%/80days）- CR of organic C-14 decreased.
Æ 90 % of organic C-14 removed by 60 days.
- CR of total C-14 (w/o TiO2) not changed. Å No evaporation of C-14

12

8. Decomposition Reaction of Methanol<Proposed decomposition reaction of methanol*5)>
CH3＋ TiO2

CH3

CH2

CH2

O

O

O

TiO2

TiO2

TiO2 TiO2OH

CO2 ＋ TiO2

OH

adsorption

Oxidation

Oxidation

Oxidation

desorption(1) Adsorbed onto TiO2, then decomposed→ Removed organic C-14 in solution could contain“adsorbed” and “decomposed” C-14
(2) Oxidized to CO2, then desorbed.
→ “Adsorbed” C-14 would be finally decomposed*5) Yamagata et al.: Bull. Chem. Soc. Jpn., Vol.62, No.4,
pp.1004-1010 (1989).

13

9. Results – Effect of Organic Forms<Removal rate of organic C-14>

Decomposed
Others (Adsorbed, etc)

Organic C-14 removal [%]

100

95%

Methanol（80 days)

80

19.9

75.2
90%

60

Formaldehyde（75 days）

Methanol

40

98%

Formaldehyde
20

23.2

66.5

Formic acid（75 days）

Formic acid

7.9

90.0

0
0

10

20

30
40 50
Time [day]

60

70

80

0

20
40
60
80
Organic C-14 removal [%]100

・Clarified decomposition of 3 organics by TiO2
・Removal rate (“adsorbed”+ “decomposed”)
Formaldehyde < Methanol < Formic Acid
14

10. Application to Waste Packages
Installation of Photocatalysts
Infill photocatalyst particles in waste packages.
<Conditions>-Infill TiO2 particle (φ2 mm)- Filling factor : 60%

Surface area/water volume：

Waste
Package

Canister

TiO2 particles

35 times as the experiments

1511. Conclusions- Clarified decomposition of organic C-14
by photocatalysts irradiated with β- rays
- Decomposition rate of organic C-14 (75 - 80days)
Methanol: 20%

Formaldehyde: 67%

Formic Acid

: 8%

- Confirmed possibility of decomposition of organic C-14
in waste packages

1612. Future Tasks
1. Performance of photocatalysts in repository- Reaction mechanism (sorption, decomposition)- Performance in reduced condition- Effect of components in ground water (Ca2+, other organics, etc.)

2. Reliability of photocatalysts- Durability of photocatalysts- Resistance to ionized radiation, heat

3. Effect to environment- Effect of H2 gas generated by photocatalytic water decomposition- Effect to corrosion of waste package materials and metal wastes

4. Others- Productivity, cost
- Handling, infilling method17

Appendix

18

Results – Decomposition Rate with Time
<Decomposition reaction of methanol>

Description as a Langmuir formula*6)

k 1 K [ CH 3 OH ]1−
[ CH 3 OH ] =dt
1 + K [ CH 3 OH ](k1:rate constant、K:equilibrium constant)<Residual organic C-14 in methanol solution>
Residual Organic C-14 [%]CH3OH+2H2O Æ H2CO3+3H2

100

10

1

0.1
0

Organic C-14 can reduced to
1/1000 by 110 days

50

100
Time [day]

150

200

＊6) Jian Chen et al., Water Research, Vol.33, No.5,
pp.1173-1180, 1999

19

Application to Waste Packages
Reaction in Waste Package

Underground repository
Waste Package
Proposed formula−Waste
packagesk K [ C − 14 ]1
[ C − 14 ] = 1
dt
1 + K [ C − 14 ](k1:rate constant、K:equilibrium constant)

Consider surface area
FillerConcrete pit

Buffer material

Flow rate of groundwater
would be very slow inside ofbentonite layer.

Organic C-14

Condition in waste package
would be assumed to be static.

20

Application to Waste Package
Installation of Photocatalysts-2

Place photocatalytic plates in waste packages.
<Conditions>- Install TiO2 plate- Infill quartz sand(Filling factor: 60%)
Canister

Surface area/water volume：

Waste
Package

TiO2 plates

1/4 as the experiments
21

Application to Waste Package
Evaluation
Evaluation on results of methanol experiments<Time required to reduce organic C-14 to 1/1000>
Case−1）TiO2 particles

4 daysCase−2）TiO2 plates

485 days
Released organic C-14 can be reduced
in a shorter period by photocatalysts.

22

Fundamental study of C-14 chemical
form under irradiated condition
NAGRA/RWMC Workshop on C-14, Oct. 27-28, 2003

JNFL
Japan Nuclear Fuel Ltd.

RWMCRadioactive Waste Management
Funding and Research Center

Hitachi Ltd.

Outline
1. Introduction
2. Basic decomposition model
3. Application to actual disposal system
4. Evaluation of C-14 chemical form
5. Conclusion

1

2

BackgroundLow molecular weight of organic C-14

Activated metal- zirconium alloy- steel alloy

corrosion- formic acid, acetic acid- formaldehyde- methanol, ethanol

Due to low sorption abilities of organic C-14, it is very important toevaluate the long-term stability of organic forms¾An inorganic form is more stable thermodynamicallyin the disposal condition (pH=12.5, Eh= -600mV).

¾In this study, irradiation effect was investigated.

Energy level¾However, high energy is required to decompose
an organic matter.

Energy barrier
Organic
InorganicOutline
1. Introduction
2. Decomposition model
3. Application to actual disposal system
4. Evaluation of C-14 chemical form
5. Conclusion4Decomposition model
Direct decomposition
Organic C-14

CO32-

Indirect decomposition
H2O

OH･

OH･ + Organic C-14 → CO32-

Indirect decomposition is a dominant process in a low organic concentration.
Decomposition model¾Decomposition reactions of organic matters should be described as follows.
¾Firstly, the validity of this model was investigated by a simple irradiation test.
Formic acid

HCOOH + 2OH･ → CO2↑+ H2OFormaldehyde

HCHO + 4OH･ → CO2↑+ 3H2O

Methanol

CH3OH + 6OH･ → CO2↑+ 5H2O

Acetic acid

CH3COOH + 8OH･ → CO2↑+ 6H2O

Ethanol

C2H5OH + 12OH･ → CO2↑+ 9H2O

5

Irradiation test
Co-60
sourceGamma
irradiation

6

Organic C-14 solution(Conc. = 10-4mol/L): experiment (filled): calculation (clear)100

Decomposition ratio (%)

メタノール
Methanol
ギ酸
Formic acid80

The experimental results agreed withthe calculated results obtained by anabsorbed energy and G-value*.

ホルムアルデヒド
Formaldehyde

Ethanol
エタノール
60

Acetic acid酢酸
計算結果は白抜き

Dose rate: 100Gy/h*G-value : OH radical number which is generated,

40

when the water absorbed 100eV.
20

0
1E+0

1E+1

1E+2

1E+3

Absorbed dose (Gy)

1E+4

Outline
1. Introduction
2. Decomposition model
3. Application to actual disposal system
4. Evaluation of C-14 chemical form
5. Conclusion

7

8

Actual conditions
Waste package (4.6m3): Gamma ray

Activated metal

Organic C-14 concentration

MortarIrradiation conditions

zConcentration of C-14 in activated metal

zDose rate by Nb-94

zCorrosion ratezAmount of water in a waste package

zSurface areazG-value of OH radical

zThe ratio of organic form
zPorosity in a waste package

Leaching rate of Organic C-14

Generation rate of OH radical

9

Estimation
Waste package (4.6m3): Gamma ray

Activated metal

MortarLeaching rate of Organic C-14

Generation rate of OH radical

6.6×10-9 mol/L/y

4.7×10-6 mol/L/y*1: Calculated from the surface area of metal,
corrosion rate, porosity, etc.

*2: Calculated by the dose rate of Nb-94
8mol of OH radicals are necessary inorder to decompose the 1mol acetic acid.

Organic C-14 becomes almost inorganic,
when 1% of OH radical is consumed forthe decomposition.

Theoretical maximum decomposition rate

5.9×10-7 mol/L/yIrradiation conditions
The value evaluated in the experiment
Decomposition efficiency**: The ratio of OH radicals used for the decomposition of organic C-14

Task

z Concentration dependencez Dose rate dependence

Irradiation conditions
Item

Conditions

Dose rate

2×10-1 - 2×102 Gy/h(Actual dose rate: 10-3 - 10-2Gy/h)Organic
C-14 Conc.

10-7 - 10-5 mol/L(Actual concentration: 10-7 -10-5 mol/L)

10

11

Experimental conditions
Irradiation condition
Dose rate: 2×10-1 - 2×102 Gy/hAbsorbed dose: 3 - 3000 Gy
Co-60
sourceGamma
radiation

20mL

z C-14 form
Acetic acid, Methanolz Concentration
10-7 - 10-5mol/L
zTemp.
zAtmospherezSolution

Addition of carrier and HCl+Ar purge

C-14
Analyses

C-14
Analyses

Total C-14

Organic C-14

* Irradiation factor : Theoretical dosenecessary for 100% decomposition

Decomposition=
Ratio(%)

Decomposition=
Efficiency(%)

25℃
Anaerobic(3%-H2 gas)
Alkaline solution(pH=10)
Actual groundwater
Total
C-14

Organic
C-14
Total C-14

Decomposition Ratio(%)
Irradiation factor*

12Appearance
Irradiation

Irradiated samples*

Inorganic C-14 separation

NaHCO3 Irradiated
未処理
ﾊﾞﾌﾞﾘﾝｸﾞ Addition
HCl
Additionpurge
添加of HCl添加
of carrier

sample*101 - 104Gy

13

Experimental resultsz The decomposition efficiency increased in proportion to theorganic C-14 concentration.
zThe dose rate dependence was not observed in this study.
Dose rate dependence
Decomposition efficiency (%)

Decomposition efficiency (%)

Concentration dependence100

C-14 form ：Acetic acid
Dose rate ：2×100 - 2×102 Gy/h
10

1

0.1
1E-9

1E-8

1E-7

1E-6

1E-5

Organic C-14 concentration (mol/L)

1E-4

100

C-14 form ：Acetic acidConc.
: 10-6mol/L
10Actualdose rate

This study

1

0.1
1E-3

1E-2

1E-1

1E+0

Dose rate (Gy/h)

1E+1

1E+2

Effects of C-14 form and groundwater 14
zThe effect of chemical form and groundwater composition
was very small.

100

Effect of Groundwater

C-14 form ：Acetic acid, Methanol
Dose rate ：2×100 - 2×102 Gy/h

Decomposition efficiency (%)

Decomposition efficiency (%)

Effect of organic form

10

酢酸C-14
Acetic acid
1

0.1
1E-9

ﾒﾀﾉｰﾙC-14
Methanol

1E-8

1E-7

1E-6

1E-5

Organic C-14 concentration (mol/L)

1E-4

100

10

C-14 form ：Acetic acid
Dose rate ：2×100 - 2×102 Gy/hAlkaline
C-14 solution(pH=10)
酢酸
Actualgroundwater
C-14
ﾒﾀﾉｰﾙ

1

0.1
1E-9

1E-8

1E-7

1E-6

1E-5

Organic C-14 concentration (mol/L)

1E-4

15

Discussion
Experimental results

Reaction of OH radical

The decomposition efficiency increased
in proportion to the organic C-14
concentration.

Generation of OH・
H 2O

OH・

Decomposition efficiency (%)

Previous study
100

Acetic acid
Methanol
Rokkasho groundwater

Decomposition

Competitive reaction

OH・ + Org. C-14
→ Inorg.C-14

OH・ + X → H2O
X : Competitive material

10

Competition model
1

0.1
1E-9

zThe decomposition efficiency should be
dependent on the organic C-14 concentration.
zThis model agrees with the experimental result.
1E-8

1E-7

1E-6

1E-5

1E-4

1E-3

Organic C-14 concentration (mol/L)
It is considered that the decomposition
efficiency is not dependent on dose rate.

Outline
1. Introduction
2. Decomposition model
3. Application to actual disposal system
4. Evaluation of C-14 chemical form
5. Conclusion

16

Evaluation of chemical form
Generation
Generation

Waste package (4.6m3)

17

Decomposition
Decomposition&&migration
migration● Chemical form
● Dose rate
● Staying time ina waste package● Leaching rate

Evaluation of organic C-14 concentration in the waste package(t − dt )dt⎧⎫⎫⎪ ⎛ 1 ⎞ T
1
1⎪⎛1⎞ T ⎪ ⎛
⎞ ⎧⎪
(
)
(
)
×
−
⋅
×
−
⋅
⋅
⋅
⋅
Cn = ⎨Cn −1 + G ⋅ dt ⋅ ⎜ ⎟
dt
D
dt
C
E
1
1
⎜
⎟
⎬
⎨
⎬× ⎜ ⎟temp
UC
2⎪⎪⎭ ⎝ 2 ⎠
⎝ ⎠
⎠ ⎩
temp
⎪⎩
⎪⎭ ⎝

Cn: Organic C-14 conc. (mol/L)

U: Staying time of Organic C-14 in waste package(y)G: Organic C-14 leaching rate (mol/L/y)

D: Theoretical maximum decomposition rate(mol/L/y)

T: Half life of C-14(5730y)

E: Decomposition efficiency(mol-1･L)

18

Estimated results
It was found that the rate of an organic form might fall sharply byconsidering the irradiation effect.
Calculated results in case1

1E-4

1E-5

1E-6

1E-7
放射線分解なし
no radiolysis
放射線分解あり◆ radiolysis
◆

1E-8

1E-9
10

100

C-14 form
Dose rate
Leaching rate
Staying time

Acetic acid
2×10-3 Gy/h
6.6×10-9mol/L/y
18000 y1000

Time (y)10000

Organic C-14 conc.(mol/L)

Organic C-14 conc.(mol/L)

C-14 form
Dose rate
Leaching rate
Staying time

Calculated results in case2
Acetic acid
2×10-3 Gy/h
6.6×10-9mol/L/y
1800 y

1E-4

1E-5

1E-6

1E-7
放射線分解なし
no radiolysis
放射線分解あり◆ radiolysis
◆

1E-8

1E-9
10

100

1000

Time (y)10000Future work

19

1. The effect of competitive substance
The effect on the decomposition efficiency must be evaluatedon the substance which coexists in the actual disposal condition.
2. The effect of low dose rate
The effect of low dose rate must be theoretically examined,
since to simulate the low dose rate experimentally is difficult.
3. Evaluation of C-14 staying time in the waste package
C-14 staying time should be evaluated considering the waste
package design.

Forschungszentrum Karlsruhein der Helmholtz-Gemeinschaft

Interactions of Carbon in a Repository
Environment
Workshop on 14C Release and Transport in Repository Environments
Wettingen, Switzerland - Oct. 27-28, 2003

B. Kienzler, V. Metz, M. Kelm,
Forschungszentrum Karlsruhe, Institut für Nukleare Entsorgung (INE)
C. Nebelung, L. Baraniak
Forschungszentrum Rossendorf, Institut für Radiochemie14C disposal in Germany•

14N(n,p)14C
17O(n,α)14C
14C specific activity:•

Zircalloy cladding
UO2, moderator (H2O):

σ = 1.48 barn
σ = 0.183 barn
1.65x1011 Bq g-1
14N:
17O:

max. 65 ppm
0.038%•

Zircalloy per ton heavy metal: 520kg(GKN I), 550kg(GKNII)
14N ~ 2 mol / t HM
17O ~ 3.2 mol / t HM•

LWR:
370 - 390 GBq / (GWe yr)
installed nuclear power in Germany:
22 GWephase-out, total life-time:
32 yrs.
Total 14C inventory in a disposal:
2.8x105 GBq
1700 g (120 mol)•pebble bed HTR (total 5x1012 Bq), LLW, tracers…..

Behaviour of 14C loaded waste•

Zircalloy: (Kaneko 2002), ZrC
Release: DOC from carbides ~2 x DIC•

HTR fuel:14CO2, depending on O2
total release < 2%•

ERAM: Al-carbides from 14C production•

14C labelled organic material: biodegradation depending on→ methane- pH- electron acceptors (O2, NO3-, Fe3+, SO42-, CO2)
CH2O + O2
CH2O + 4/5 NO3 + 4/5 H+
CH2O + 8 H+ + 4 Fe(OH)3
CH2O + ½ CO2→ CO2 + H2O→ CO2 + 2/5 N2 + 7/5 H2O→ CO2 + 11 H2O + 4 Fe2+
→ CO2 + ½ CH4∆G°=-502.4 kJ mol-1∆G°=-476.9 kJ mol-1∆G°=-116.0 kJ mol-1∆G°=-92.9 kJ mol-1

Recent Experimental
Investigations
for FB Asse
ERAM

SolidsSolutions
Inactive conditioning
min. 6 weeks
Separation
Solids - Solutions

Steps for conditioning-solids- solutions

Conditoned Solid

Condit. Solution

Active conditioning
conditioned solution+
radioactive tracer(min. 6 weeks)

standard solution II

Sorption experiments (batch)Standard solution II+ conditioned solid (min. 0.5 years)

14Methane Sorption
Solids:sorel concrete

Solutions: MgCl2-rich brine

Monitoring the CH4/Ar ratio
Result:
CH4/Ar ratio constant within a deviation of 5%® Total methane sorption onto sorel phases
below 0.2 mmol CH4/kg solid material

14Carbonate Solubility / Sorption
Solids:salt concrete
sorel concrete“Grauer Salzton”

pHsalt concrete
sorel concrete
Grauer Salzton

Solutions: MgCl2-rich brine
NaCl brine

NaCl
10.6
9
7.3

MgCl2
6
6.7
5.7

Solubility

NaCl
2.5x10-5 - 1.2x10-4 mol/l

MgCl2
1.6x10-3 - 6.7x10-3 mol/l

SorptionA − A V0
Rs = 0⋅Am

NaCl
Rs ~ 3000 ml/g

MgCl2
Rs = 2.3 ml/g to 11 ml/g

Asse Salt Mine+200 m13 emplacement rooms≈1300 drums intermediate-level waste• ≈125000 drums low-level waste• ≈1015 Bq total RN inventory
mainly An: ≈120 t U, ≈80 t Th, ≈12 kg Pu• intrusion of MgCl2-rich brine expected• >30000 t Portland cement (OPC)• > 670 t NO3• 2800 t organic carbon ⇒ degradation
to CO2, inorganic carbon (DIC), e.g.

sea level-400 mC6H10O5 + 4.8H+ + 4.8NO3- = 7.4H2O + 6CO2 + 2.4N2

affecting geochemical environment⇒ affecting radionuclide release-800 mbrine

Quasi-closed system modeling approach
NATURAL OPEN SYSTEMEMPLACEMENT ROOM
GASES

rate

CO2, H2eq.

ACCESS GALLERYSOLUTION
rate

ions,
complexes,
rate
colloids
eq.

SECONDARYSOLID PHASES

pure solids,
solid solutions

QUASI-CLOSED MODEL SYSTEM

Reaction of cement in Q-brine + DIC input

reaction-10.47 kg cement (kg H2O)

reaction-10.40 kg DIC (kg H2O)

10

Ca
1

14
13

Mg

12

-1

11

0.1

10
9

pH

8

1E-3

7
6

1E-4

5
4

1E-5

C

3

1E-6
0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8
-1

progress
Zi / kg reactant(kg(kg
HHO) -1
kg reaction
cement (kgH2O)-1kg DIC
2 2O)

2
0.9

pH
6

6.5

7

7.5

8

8.5

-5

-4

-3

-2

-3

log (Am mol-1 kg H2O)

0.01

pHEQ3/6

concentration / mol (kg H2O)

2

-4
-5
-6
-7
-8
-7

-6

log (CO32- mol-1 kg H2O)

-1

Recommended buffer material

Mg-depot provided by K-UTEC GmbH• ≈69 wt.% brucite + Mg-oxychloride• ≈25 wt.% halite• ≈ 6 wt.% accessory minerals
3µm

Mg-depot (SEM: Klaus Spieler, INE)

INE recommendation to FB Asse:brucite + Mg-oxychloride“Mg depot”
1µm

brucite (SEM: INE)

10µm

Mg-oxychloride (SEM: INE)

studying effectivness• buffering pH• limiting [CO3--]• resulting in low [An]Reaction of cement + Mg-depot in Q-brine + DIC input

10

pH
6

reaction-10.40 kg DIC (kg H2O)

Ca
1

14
13

7

7.5

8

8.5

-5

-4

-3

-2

-4
-5
-6
-7
-8
-7

Mg

12

-1

-6

log (CO32- mol-1 kg H2O)

11

0.1

10
9

0.01

pH

8

1E-3

7

pHEQ3/6

concentration / mol (kg H2O)

6.5

-3

log (Am mol-1 kg H2O)

reaction
0.71 kg cement (kg H2O)-1
1.96 kg Mg-Depot (kg H2O)-1

2

6
1E-4

5
4

1E-5

C

3

1E-6
0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7 0.1
0.8

0.9
1.1
0.2 1.0
0.3 0.42
1.2
1.3 0.7
1.4
0.5 0.6-1

progressO)H2O)-1
kg reaction
cement (kgH2O)-1 Zi / kg reactantkg(kgDICH(kg2

Magnesite
precipitation-1

Reaction of cement + Mg-depot in Q-brine + DIC input

10

pH
6

reaction-10.40 kg DIC (kg H2O)

Ca
1

14
13

7.5

7

8

8.5

-3

-2

Am

-4
-5
-6
-7
-8
-7

Mg

12

-1

-6

-5

-4

-1

log (CO32- mol-1 kg H2O)

11

0.1

10
-2

8

1E-3

7
6

1E-4

-1

pH

log [Pu(IV) mol kg H2O]

9

0.01

pHEQ3/6

concentration / mol (kg H2O)

6.5

-3

log (Am mol-1 kg H2O)

reaction
0.71 kg cement (kg H2O)-1
1.96 kg Mg-Depot (kg H2O)-1

2

Pu

-4

1
10-2

-6

10-3.5
-8

10-5

-10

0

5
-12

4

1E-5

C

0.1

0.2

0.3

0.4

0.5

4

6

8
+

-log [H ]

3

1E-6
0.0

2

0.6

0.7 0.1
0.8

0.9
1.1
0.2 1.0
0.3 0.42
1.2
1.3 0.7
1.4
0.5 0.6-1

progressO)H2O)-1
kg reaction
cement (kgH2O)-1 Zi / kg reactantkg(kgDICH(kg
2

(...)

10

12

Autoclave experiment: formation of carbonates

100

haliteDIC

magnesite

150

Q-brineMg-hydroxocarbonate200

Mg-hydroxocarbonate

intensity

250

Mg-oxychloride
magnesite
halitemagnesite

Mg-oxychloride
Mg-hydroxocarbonate
halite300

magnesite

Mg-depot

350

autoclave experimentMg-depot in Q-brine<17 bar CO2:
formation of magnesite
besides metastable
Mg-hydroxo-carbonates

50
0
0

10

20

30

40
2θ

50

60

70

80

Improving thermodynamic data for brucite / Mg-oxychloride
10.5

Equilibrium pHEQ3/6 values in
MgCl2 solutions saturated with
Brc, Mg-Oxy (25°C)

log K°s (Mg-Oxy) = 26.0 ± 0.2

Brc
Mg(OH)2(cr)9.5

pH(EQ3/6)

log K°s(Brc) = 17.1 ± 0.2

10.0

9.0

solid lines: calculatedwith improved databasesolid transformation

8.5
8.0

dotted lines: calculatedwith thermodynamic data of
EQ3/6, GWB, CHESS,SUPCRT92 ... databases

Mg-OxyMg2(OH)3Cl.4 H2O(s)

7.5
7.0
0

1

2

3

4

5

mMgCl2 (mol (kg H2O)-1)
Altmaier, M., Metz, V., Neck, V., Müller, R. & Fanghänel, Th.: Geochim Cosmochim. Acta (in press)

6

Pu solubility
pHEQ3/6
5

6

7

8

9

10

11

12

13

-1

log ([Pu] mol kg H2O)

00
Pu(VI)

-2

-2
Pu(V)

-4

-4
Pu(III)

-6

-6

-8

-8

Puges

Pu(IV) coll.
Pu(IVam/Vaq)-10

Pu(IVam/Vaq/VIaq)-10

Pu(IV)

-12
5

6

7

8

9

10
+

- log [H ]

11

12

13

-12
14

Summary and Conclusions


14C load from irradiated zircalloy and spent fuel some from THTR andorganic tracers.
Release during storage of THTR spent fuel by contact with air and gamma
radiation generating CO2.

In rock salt, dissolved carbonate species sorb onto carbonate containing
solids by isotopic exchange.

In cement dominated systems, high distribution coefficient between DIC and
DOC is observed (>1000 ml g-1).

Interaction of CO2 gas with Mg bearing material: formation of magnesite andmagnesium-hydroxo-carbonate.



Weak sorption of 14CO32- onto salt concrete in MgCl2-rich brine. Sorel
phases reduce dissolved 14C by more than 100 during 0.5 yr.



Sorption of methane onto solids could not be verified.

Study on Chemical Behavior of
Organic C-14 under Alkaline
Condition
October 27-28, 2003
JNFL
RWMC
TOSHIBA

1

Contents
1.Background
2.Objective
3.Experimental Procedure
4.Results
5.Summary
6.Future Study

2

1.Background
2.2
2
1.8
1.6
1.4
1.2
1
0.8
0.6
0.4
0.2
0
-0.2
-0.4
-0.6
-0.8
-1
-1.2
-1.4
-1.6
-1.8

H2C2O6?
H2CO4?
logPCO2=0

CO2

b

H2CO3

-2

Zr+++

-4 -6

HCO3-

logC=0
a

CO3--

C

③

logCH4=0

CH3OH

CH4
②
0

2

4

6

8

10

12

1.4
1.2
1
0.8
0.6
0.4
0.2
0
-0.2
-0.4
-0.6
-0.8
-1
-1.2
-1.4
-1.6
-1.8
14 -2
-2.2
-2.4
-2.6

Zr2O7?
ZrO3?
Zr2O5?

b

ZrO++

-4

-6

①

Zr
0

2

：Disposal

ZrO2･2H2Oa

0 -2

HZrO3=

4

6

8

10

12

14

①Low Eh value around the surface of activated metals
caused corrosion reaction②In this condition, are organic carbons(C-14:released frommetal) stable ?
③In disposal condition, is inorganic carbon stable ?
The Change of C-14 species from activated metals
in disposal condition32.Objective
The study on the change of the chemical forms
from activated metals in disposal condition.
-The disposal facility made from cement materials
etc.is alkaline and in a reduced condition.

4

3.Procedure（１／２）（1）Leaching Test of Organic C-14 from Activated Metal Waste(Test No.1)
The Leaching for
Cutting Powderof Activated
Metal
・The Leaching・Simulated
・pH 10・Anaerobic（3％H2／97%N 2）
・Leaching
1 monthThe Leaching test

・Leaching
1 MonthChemical Form

Removal of Co-60

・The Cation exchange forremoval of Co-60
to avoid the radiolysis
・pH adjustment

・High performanceliquid chromatography
・Total organic carbon andinorganic carbon
analｙsis
・Time
1,3,6,12 Monthｓ after theremoval of Co-60

5

3.Procedure（2／2）（2）Immersing Test of Organic Compounds in Alkaline Condition(Test No.2)
Preserve in
Alkaline Solution

・The Chemicals
Formic Acid
Acetic Acid
Formaldehyde
Acetaldehyde
Methanol
Ethanol・pH

ChemicalAnalysis・Total organic carbon andinorganic carbon
analysis・Time
1〜15 monthｓ

64.Results（1／２）（1）Test No.1
The change in the ratio for each organic to to totalorganic carbon

The change in the ratio of organic carbon
The Ratios of Each Organics(%)

Organic Carbon Ratio/The Organic
Cabon Ratio at the start

100%

80%

60%

40%

20%

50

40
CH3COOH
HCOOH
HCHO

30

C2H5OH
CH3OH
Unknown

20

10

0%

0

1

3

6

12

Time (month）

Time

0
0

3

6

9

12

Time (month）

The Ratio of Organics in Total Carbon
Data of Measurement The Data nomalized

0 month

74.9%

100%

1month

74.6%

99.6%

3 month

66.2%

88.4%

6 month

71.6%

95.6%

12 months

67.3%

90.0%

7

4.Result（２／２）（1）Test No.2

The change in concentration of organics

100%
90%

The Residual Ratio（％）

80%
70%
60%
50%
40%

Methanol(pH8)30%

Methanol(pH12.5)

20%Ethanol(pH8)10%

Ethanol(pH12.5)

0%
0

2

4

Added Organics
Carboxylic Acid
Aldehyde
Alcohol68
10
Time（Month）

12

14

16

18

The Residual Ratio (after 14 months)
pH 8

pH 12.5

Formic Acid

88%

71%

Acetic Acid

91%

84%

Formaldehyde

90%

80%

Acetaldehyde

90%

77%

Methanol90%

73%

Ethanol

88%

72%

8

100%
90%
80%

Residual Ratio（％）

70%
60%
50%
40%

Formic acid pH8
蟻酸(pH8)還元剤なし

30%

Formic acid pH12.5
蟻酸(pH12.5)還元剤なし

20%

Acetic acid pH8酢酸(pH8)還元剤なし

10%

Acetic acid pH12.5
酢酸(pH12.5)還元剤なし

0%
0

2

4

6

8

10
Time（Month）

12

14

16

18

20

9

100%
90%
80%

Residual Ratio（％）

70%
60%
50%
40%
Formaldehyde pH8ﾎﾙﾑｱﾙﾃﾞﾋﾄﾞ(pH8)還元剤なし
ﾎﾙﾑｱﾙﾃﾞﾋﾄﾞ(pH12.5)還元剤なし
Formaldehyde pH12.5
ｱｾﾄｱﾙﾃﾞﾋﾄﾞ(pH8)還元剤なし
Acetaldehyde pH8
ｱｾﾄｱﾙﾃﾞﾋﾄﾞ(pH12.5)還元剤なし

30%
20%

Acetaldehyde pH12.5

10%
0%
0

2

4

6

8

10
Time（Month）

12

14

16

18

20

10

5.Summary
The organic C-14 released from the activatedmetals might change to inorganic carbon in thedisposal condition (alkaline,reduced)
In the higher pH Condition, the rate of change toinorganic carbon might be faster.
The organic carbon might change to inorganiccarbon slowly.
116.Future Study
We are going to study the hydrolysis reaction fororganic C-14 in alkaline condition and velocity ofthis reaction.
If the hydrolysis of organic C-14 in alkalinecondition occurred at a disposal site, it would bepossible to rationalize engineering of disposal
facility.

12

Investigations of Distribution
Coefficients for C-14 from ActivatedOctober 27-28, 2003
JNFL
RWMC
MHI
NDC
HITACHI Ltd.
TOSHIBAContents
1. Objective
2. Experimental Procedure
3. Results
4. Discussion
5. Summary

１．Objective• Because the C-14 released from the activated metals
mainly forms organic compounds that weakly sorb on
engineering barriers, effective absorption materials fororganic C-14 or oxidation to inorganic C-14 are required forrationalization of engineering for disposal facilities.
• The distribution coefficients of cements for C-14 released
from activated metal were measured in this study.
For other types of materials suitable for engineering barriers,
the distribution coefficient experiments were carried out inthis study too.

２．Procedure (1/3)(1) The conditions for the distribution coefficientmeasurements for C-14 from activated metal① Activated Materials(a) Activated Zirconium Alloy（ｈuｌｌｓ）（Metallic sample and the sample
covered with zirconium oxide）(b) Activated stainless steel（without surface oxides）② Liquid Phase

Simulated Groundwater（Anaerobic alkaline condition）③ Cement

OPC and mixed cements (OPC:BFS=1/9)④ Solid Liquid Ratio

1g/10ml

ＯＰＣ：Ordinary Portland Cement
Mixed Cement ; OPC:BFS=1/9 BFS;Blast Furnace Slag

２． Procedure (2/3)(2) The Method of the distribution coefficientmeasurements for C-14 from activated metals
The Cutting Powderof Activated StainlessSteel 100g
Simulated Groundwater
1000mlAtmosphere：
3%H2+N2
Temp.：
Room Temp.

Glove Box for Settling
Atmosphere：3%H2+N2
Temp.：Room Temp.
Settling Time：Max 12 Months•Leaching 1 MonthIon Exchange for
Co-60 Removal

Each Solution for Experiments
・The concentrations of organic andinorganic C-14 were measured
individually.
・Calculation Kd values fromthese data

・Cement：OPC
・Cement：OPC

Solid Liquid Separation

Glove Box Kd values
Atmosphere：3%H2+N2
Temp.：Room Temp.
Time：７Days２． Procedure (3/3)(3) The Measurements for Kd values of organic C-14 foreffective materials① Materials and Organics
Materials

Organic Carbons

Notes

20 Type5 types of organiccarbon compounds
spiked with C-14

* Based on the analysis for
activated stainless steel
leaching experiment② Solid Liquid Ratio ： 1g/10ml

３．Result (1/4)(1) The measurements for Kd values of C-14 from
activated metals① Activated Zirconium Alloy “Organic C-14”(ml/g)
CementOPC

Mixed
cementRun NoMetallic
SampleSample covered
with Zirconium
Oxide

Ave.

1

1.9

5.8

−

2

4.6

2.5

−

Ave.

3.3

4.2

3.7

1

3.6

3.6

−

2

2.7

8.8

−

Ave.

3.2

6.2

4.7

The concentration of inorganic C-14 was under the detection limit. 6

３． Result(2/4)(1) The measurements for Kd values of C-14 from
activated metals(ml/g)②Activated Stainless Steel
Item

RUN A

RUN B

Ave.

Leaching Time

11Months

1 Months-

Settling Time

0 Month0 Month1Month3 Months

6 Months

12 Months

Ave.

-

The Ratio for TOC(C-14)

37%

74.9%

74.6%

66.2%

71.6%

67.3%

-

-

Inorg.

580

245

486

1060

873

870

707

686

Org.

7.5

9.3

5.8

3.5

5.9

2.9

5.5

5.8

Total

35

15

11

10

12

9.1

11.4

15.4

Inorg.

90

-

-

-

-

-

-

-

Org.

12

-

-

-

-

-

-

-

Total

33

-

-

-

-

-

-

-

CementOPC
Mixed
Cement7

３． Result(3/4)(2) The experiments on effective materials for organic C-14 sorption① selecting materials with high Kd values using acetic acid-C-14(ml/g)
Materials

Minerals in
CementNaturalMinerals

Artificial
MineralsAcetic Acid

CSHgel 0.65

0.9

CSHgel 0.90

0.8

CSHgel 1.65

0.7

Ettringite

7.3

Monosulphate

0.8

Tobermolite

1

Hydrotalcite（OH Type）

14.1

Illite5.9

Acid Clay

39.1

MgO

1.8

Al2O3

2.1

TiO2

0.6

ZrO2

1.5

Fumic Acid

<0.1

Coal

4.3

Halloysite

64.9

Ferric Oxides

0.1

Bismuth Phosphate

0.3

Charcoal

19.7

Asphalt

0.2

8

３． Result(4/4)(2) The experiments for effective materials for each organic carbon
compounds sorption
ml/g②Kd values experiments
Oraganic Carbon Compounds
Materials

Acetic Acid

Formic Acid

Formaldehyde

Methanol

Ethanol

Ettringite

7.3

16

6

0.4

Hydrotalciteト

14

21

7

0.4

Illite

5.9

0.1

3.8

1.2

8.4

Japanese Acid
Clay

39

7

3.2

0.5

13

Halloysite

65

15

3.8

0.3

12

Charcoal

20

11

43

2.5

17
9

４．Discussion① The Kd value of cement for inorganic C-14 released
form activated stainless steel is 1060ml/g〜245ml/g,
and that for organic is 9.3ml/g〜3.5ml/g.
② There are no differences between the organic C-14 fromthe activated zirconium alloy and that from the activatedstainless steel.
③ The Kd value of OPC for organic C-14 is the same asthat for mixed cement.
④ Several minerals are effective for organic carbon
sorption. Regarding their use as engineering barriers,
further investigation is required.
10

５．Summary¾ The cement Kd values for C-14 from activatedzirconium alloy and activated stainless steel were
measured in this study.
¾ Preparation of a Kd values database for someorganic carbons, e.g. carboxylic acids and alcohols,
and inorganic carbon would be important for setting
up the C-14 in the activated metals.

11

Migration of C-14 in Activated Metals underAnaerobic Alkaline Condition
October 27-28, 2003
The Kansai Electric Power Co.
Chubu Electric Power Co.
RWMC
TOSHIBAMHI
NDC
NAGRA / RWMC Workshop on C-14

1

Migration of C-14 in Activated Metals under Anaerobic Alkaline Condition

1. Objective
2. Corrosion Test
3. C-14 Leaching Test
4. Discussion
5. Conclusion

NAGRA / RWMC Workshop on C-14

2

Objective– For the safety assessment of radionuclide migration, it is necessary
to access not excessively conservatively but actually.
– C-14 is considered an important nuclide for the safety assessment of ageological repository facility.
– It is the aim of this investigation to provide data relevant to design themodel of C-14 migration mechanism, by dual determinations ofleaching rate and corrosion rate.

NAGRA / RWMC Workshop on C-14

3

Corrosion Test -ConditionMaterial
Of Specimen• Zirconium Alloy• Stainless Steel• Nickel Alloy

Shapeof Specimen• Plate as Flag

Glass Tube

Specimen Flag

Epoxy Resin

Surfaceon Specimen• Elimination of Oxide-Film by Polishing

Environmentof Test• Anaerobic Alkaline Condition

Methodof Measurement

Lead• Polarization Resistance Measurement& Best-fit Curve Calculation

NAGRA / RWMC Workshop on C-14

4

Corrosion Test
-Method of Corrosion Rate Measurement- Polarization Resistance Measurement
Possible to measure the small
corrosion current over a long periodof time- Best-fit Curve Calculation
Possible to obtain the corrosion 3%H -N
parameters by graphical analysis ofpolarization curve- Reference Electrode use same Material
for Working Electrode
Possible to keep the experiment Pt as Countercondition easy by using a simple Electrodeexperimental setup
2

Personal
ComputerPotentiostat/Galvanostat
3%H2-N2

2

Sample as ReferenceElectrode

Sample as Working
Electrode

NAGRA / RWMC Workshop on C-14

5

Corrosion Test
-Comparison with Alternate Methods1.0E-1

Corrosion Depth ( µ m)

ANOTHER WAY MEASUREMENTPOLARIZATION RESISTANCEMEASUREMENT

1.0E-2

1.0E-3
Ag ALLOYSTAINLESS STEEL

Corrosion Test -Results : Corrosion RateCorrosion Rate (μm/y)

1.0E+0−−●−：Stainless● − ：Stainless SteelSteel− ▲ − ：Inconel Alloy−−▲−：Nickel■ − ：Zilcaloy Alloy−■−：Zirconium Alloy

1.0E-1

1.0E-2

1.0E-3
0

2

4

6

8

10

12

Test Period (Month)
NAGRA / RWMC Workshop on C-14

7

C-14 Leaching Test -ConditionMaterial of Specimen • Activated Zirconium Alloy• Activated Stainless Steel• Activated Nickel Alloy
Shape of Specimen• Activated Zirconium Alloy
Tube• Activated Stainless Steel / Activated Nickel Alloy
Plate

Surface on Specimen • Elimination of Oxide-Film by Polishing
Environment of Test

Specimen• Anaerobic Alkaline Condition

Test Solution
Test Solution

Immersion
1 ~ 11.5 months

NAGRA / RWMC Workshop on C-14

Analyze
Quantity of C-14

8

C-14 Leaching Test -ResultsActivated Zirconium Alloy

Bq/Unit

Test Period (Month)

5.5

9

11.5

-

1.1×101

1.5×101

1.6×101

Activated Stainless Steel
Test Period (Month)

Bq/Unit1

3

6High Irradiated

8.7×10-1

7.9×10-1

1.9×100

Low Irradiated4.3×10-1

2.0×100

ND

Activated Nickel Alloy

Bq/Unit

Test Period (Month)

1

3

6

11

-

ND

ND

ND

2.9×10-1

NAGRA / RWMC Workshop on C-14

9

Discussion -Zirconium AlloyLeaching Test Result ≈ Calculated value from Corrosion Test Results● ：Leaching：Hull Specimen(Result of Leaching Test)●
Test−−−：HullSpecimen(Calculated Result by Corrosion Rate)−−：Corrosion
Test

2

C-14 Leaching Rate (/cm )1.0E-04
1.0E-05
1.0E-06
1.0E-07
1.0E-08
1.0E-09
0

2

4

6

8

10

12

Test Period (Month)
NAGRA / RWMC Workshop on C-14

10

Discussion -Stainless SteelLow IrradiatedHigh Irradiated: Leaching Test Result ≈ Calculated value from Corrosion Test Results: Leaching Test Result < Calculated value from Corrosion Test Results●
StainlessSpecimen(Result ofSteel
Leaching
Test)● ：High-irradiated：Leaching Test
( HighSteelirradiated
StainlessSpecimen)−−：High-irradiated
Stainless
SteelSpecimen(Calculated
ResultbyCorrosion−−：Corrosion Test ( High irradiated Stainless Steel Specimen )Rate)▲ ：Leaching Test ( Low irradiated Stainless Steel Specimen )▲：Low-irradiatedTest
StainlessSpecimenStainless(Result of Leaching
Test)−−：Corrosion( LowSteelirradiatedSteel Specimen)
Low irradiated Stainless Steel Specimen (Calculated Result by Corrosion Rate)2

C-14 Leaching Rate (/cm )1.0E-03
1.0E-04
1.0E-05
1.0E-06
1.0E-07
1.0E-08
0

2

4

6

8

10

12

Test Period (Month)
NAGRA / RWMC Workshop on C-14

11

Discussion -Nickel AlloyLeaching Test Result ≈ Calculated value from Corrosion Test Results●●：Inconel
Alloy Specimen：Leaching
Test (Result of Leaching Test)−−：Inconel
Alloy Specimen−−：Corrosion
Test(Calculated Result by Corrosion Rate)2

C-14 Leaching Rate (/cm )1.0E-04
1.0E-05
1.0E-06
1.0E-07
1.0E-08
1.0E-09
0

2

4

6

8

10

12

Test Period (Month)
NAGRA / RWMC Workshop on C-14

12

Conclusion
The C-14 leaching test and the corrosion test have been
carried out to design the model of C-14 migration
mechanism.
– The C-14 leaching test results coincide approximately
with the leaching rate calculated from corrosion rates.

Our plans for the near future are:
– The estimation about the influence of fluctuation in
disposal environment parameters for C-14 migration
behavior.

NAGRA / RWMC Workshop on C-14

13

Modelling the Partitioning andTransport of C-14 in a Microbially
Active LLW Site
Joe Small
Nuclear Sciences and Technology Services (NSTS)

NAGRA C-14 Workshop 28th October, 2003

File ref:Page 1

Introductionz Carbon is a key reactive element in LLW

resultingfrom its organic content and the microbiologicaland geochemical processes that occur in thesurface and near-surface.

z Realistic assessment of C-14 release from LLW

requires consideration of the various organic andinorganic reactions that occur in the near-field thatinvolve carbon.

File ref:Page 2Aims
z Presentation of a mechanistic based modelling

approach to consider the partitioning of C-14
among reactive carbon species.
z Discussion of isotope fractionation effects.
z Discuss how such models are used in performanceassessment calculation of the Drigg LLW site, UK.

File ref:Page 3

The Drigg site
Drigg
Trenches(1959-1995)

Vault 8(1988 - present)

File ref:Page 4

Drigg LLW & C-14
z Drigg LLW comprises organic (cellulosic) and ironwaste and has the potential for gas generation andgeneration of anaerobic conditions.
z The form of the C-14 inventory in LLW is, ingeneral, poorly constrained and may be distributed
among activation products in steel and concreteand graphite as well as being associated withreactive cellulose waste.
z For the Drigg PCSC it is assumed, conservatively,

to consider C-14 present in the form of cellulose.

File ref:Page 5

Fate of C-14 in LLW

Through processes of LLW waste degradation C-14
has the potential to be redistributed to various
phases e.g.
– Carbonate phases (primarily associated with cement
grout)–Residual organic matter (microbial biomass)–Gases CO2, CH4–Aqueous species HCO3-, CH3COO-, complex organics

File ref:Page 6

Modelling the Drigg
near-field
BNFL-NSTS has developed the GRM reactivetransport code to model biogeochemical processes of
LLW degradation.
The GRM code couples various process:• Microbial processes of organic degradation and mediation of redox
reactions• Metal corrosion• Chemical speciation, mineral precipitation and dissolution• Gas exchange and reaction• Radionuclide sorption• Radioactive decay• Groundwater flow

The GRM code includes specific subroutines that follow thereaction and transport of C-14
File ref:Page 7

The GRM-DRINK model
Reaction-transport
calculation are performed
using a finite difference
grid
Reactive calculations are
performed in a each of
the 63 cells representing
the Trenches and Vaults
to determine chemical
conditions
The model outputs anaqueous and gaseous
source term ofradionuclides including
C-14
File ref:Page 8Model Results:
pH variation - trench cells
9.0
8.5
8.0

Groundwater pH

7.5

pH

7.0
6.5
6.0
5.5
5.0
4.5
4.0
10

100

1000

10000

Time, years
File ref:Page 9Model Results:
Redox variation - trench cells
64Groundwater pe

pe

2

0

-2

-4

-6
10

100

1000

10000

Time, years
File ref:Page 10

Model Results:
acetate - trench cells
4.E-02
3.E-02

Acetate, mol/l

3.E-02
2.E-02
2.E-02
1.E-02
5.E-030.E+00
10

100

1000

10000

100000Time, years
File ref:Page 11Model Results:
Calcite - vault cells
1.E+02

Calcite mol/l

1.E+01

1.E+00

1.E-01

1.E-02

1.E-03
10

100

1000

10000

100000Time, years
File ref:Page 12

C-14 partitioning
For each reaction involving carbon, C-14
released from the reactants is redistributed into
the product species.
z The C-14 content of each species is followed as a fractionof the total moles of carbon present in that species.
z The C-14 fraction of each product species is recalculated ateach reaction as a average for that species in eachcalculation cell

File ref:Page 13Model Results:
C-14 aqueous - trench cells
1.E-08
1.E-09Aqueous considers
HCO3- & CH3COOspecies

1.E-10C-14 aqueous mol/l

1.E-11
1.E-12
1.E-13
1.E-14
1.E-15
1.E-16
1.E-17
1.E-18
1.E-19
1.E-20
10

100

1000

10000

100000Time, years
File ref:Page 14

C-14 gas moles

Model Results:
C-14 gaseous - trench cells
1.E+00
1.E-01
1.E-02
1.E-03
1.E-04
1.E-05
1.E-06
1.E-07
1.E-08
1.E-09
1.E-101.E-11
1.E-12
1.E-13
1.E-14
1.E-15
1.E-16

Gases considers both
CO2 & CH4

10

100

1000

10000

100000Time, years
File ref:Page 15

Model Results:
C-14 solid - trench cells
1.E+00
1.E-01

C-14 solid moles

1.E-02
1.E-03
1.E-04

Solid C-14 includes:• disposed cellulose waste,• carbonate minerals and• biomass

1.E-05
1.E-06
1.E-07
1.E-08
10

100

1000

10000

100000Time, years
File ref:Page 16

Model Results:
C-14 solid - vault cells
1.E+01
1.E+00C-14 solid moles

1.E-01
1.E-02
1.E-03

Secondary carbonate formed in the
cement grout immobilises C-14

1.E-04
1.E-05
1.E-06
1.E-07
1.E-08
10

100

1000

10000

100000Time, years
File ref:Page 17

C-14 modelled redistribution - single trench cell
1.E-01

C-14 released

1.E-02

Cellulose

Biomass

1.E-03

Carbonatemineralsmoles C14

1.E-04

Aqueous1.E-05
1.E-06

1.E-07

Gaseous1.E-08

1.E-09

1.E-10
1

10

100

1000

10000

100000Time, years
File ref:Page 18

C-14 modelled redistribution - single vault cell
1.E-01

C-14 released
Cellulose

1.E-02

Carbonate minerals

1.E-03

Biomass

moles C14

1.E-04

Aqueous1.E-05
1.E-06

1.E-07

1.E-08Gaseous1.E-09

1.E-10
1

10

100

1000

10000

100000Time, years
File ref:Page 19

Isotope fractionation
The fractionation of C-14 and C-12 during biogeochemical
processes has the potential to influence the partitioning of C-14
during waste degradation.
C-13/C-12 fractionation is extensively researched and is an
important geochemical tool. Fractionation results from slightdifferences in the strength of chemical bonds of C-12, C-13
and C-14.
Fractionation affects both inorganic and biological processes
and there is the potential to deplete or enrich C-14 inproducts of LLW degradation.

File ref:Page 20

Consideration of isotope fractionation
The extent of isotopic fractionation between two phases (A&B)
is given by the fractionation factor α.
13
Phase

File ref:Fractionation Factor (α)

CO2 gas (reference)

1.0

Dissolved Carbonate

1.1

Acetate0.8

Microbial Biomass

0.9

Carbonate Minerals

1.2

C A /12C A
α A− B = 13 12
CB / CB

Estimated values of α for
C-14/C-12 for reactions
between species in the
GRM model

Page 21

Effect of fractionation
1.00E-02
CO2
CO3With fractionation

ACET
BIO

kmol C-14 in whole site

1.00E-03

MIN

No fractionation

LOST

1.00E-04

1.00E-05

1.00E-06
10

100

1000

10000

100000Time, years
File ref:Page 22

Summaryz In LLW microbial and geochemical processes influence thereactions of carbon and hence the release and transport ofC-14
z A modelling approach has been developed to examine thepartitioning and release of C-14 from LLW through thegaseous and aqueous pathways
z Isotope fractionation effects have been considered andhave been shown to be insignificant
z The model has been used to provide a cautious-realistic

assessment of C-14 release for the Drigg safety case whichshows that around 80% of the C-14 inventory is immobilisedby chemical processes within the near-field
File ref:Page 23

Modelling the generation of C-14
containing gases
Sarah Vines
October 2003

NirexNirex is the UK waste management organisation,
providing options for the long-term management ofradioactive materials

Phased Geological Long-term Management ConceptAssessments of gas generation for• Providing packaging advice to waste producers• Modelling the operational period of a repository• Modelling the post-closure period of a repository

C-14
C-14 has the potential to be a
key radionuclide in the gas pathway

So far only C-14 in organic
waste considered ingas assessments

Wastes containing C-14 in the1998 UK inventory• Irradiated steel, 1670 TBq (Hydrocarbons?)• Irradiated Zircaloy, 21 TBq (“Organic form”?)• Irradiated Magnox, 29 TBq (acetylene?)• Irradiated uranium, 4.7 TBq (methane etc?)• Irradiated aluminium, <7 TBq (methane?)• Irradiated graphite, 1800 TBq (dissolved CO2?)• Barium carbonate, 205 TBq (no gas release)• Organic molecules, 670 TBq (CO2 or CH4)

Further work on sources of C-14
• Graphite experiments ongoing– Alkaline leaching of graphite, with gas
measurement• Metal carbides– Data presented here?
– Monitoring of Magnox wastes during packaging

New model of gas generation (SMOGG)
Considers release of C-14 in gas from• Corrosion of irradiated metal• Leaching of irradiated graphite• Microbial degradation of organic molecules

Conditions• Water– Initial amount specified by the user
– Additional water from diffusion & resaturation– Eventually becomes unlimited• Oxygen– aerobic during transport and storage– becoming anaerobic post closure• Temperature– Profile set by the userCorrosion
Rate of C-14 release(methane)Acute / chronic
corrosion rate

Temp effect on
corrosion rate

Waste metal
sphere radius

Aerobic / anaerobic
corrosion rate

Mass of C-14

Distribution of
C-14

Microbial degradation of organic waste Reaction scheme
Cellulose

Cellulose

Soluble cellulose

Stopped

Glucose /small molecules

ISA

Aerobic or
N2 / SO42-

Reactive

Anaerobic

CO2

H2

CH4

Microbial degradation (2)Kinetic modelRates of cellulose
degradation
Rate of glucose / ISA
degradation

Amount of nitrate &sulphate present

C-14 in small
molecules

Graphite leaching
Rate of C-14 release(CO2)

Mass ofgraphite

Activityof C-14

Initialrelease rate

Carbonation

Fraction of CO2 removed
by carbonation

Radiological consequences
CO2

Methanecarbonation
Release inbuildings
Risk depends on:
Release area
Consumption by microbes in soil
Tolerable release rate is 2.4 10-3 TBq/year,
to surface area 10,000m3

ReleaseoutdoorsComparison with GAMMON• Comparison of new model with GAMMON• GAMMON represents complex microbial
reactions - difficult to validate• C-14 from microbial degradation only (bothGAMMON and SMOGG)• SMOGG calculates more CH4 and less CO2

Repository Operation and Closure Timing andConditions, GAMMON & SMOGG Models
Stage

Year

Temp (oC)Wateravailability

Oxygenavailability

Emplacement

2040 - 2090

35

Pore space incontainers
initially water
filledAerobic

Care andmaintenance2090 - 2140

35

Continue

Aerobic

Backfilling andclosure2140-2150

80 for 5 years
50 for 5 years

Continue

Aerobic

Post-closure

2150 -

50 for 100 years
35 subsequently

Resaturates allpore space

Oxygen present
at closure isconsumed

Comparison of SMOGG and GAMMON Active Gas Generation
Rates, on Basis of Unshielded Intermediate Level Waste
Inventory from 2003 Update of Generic Documents

H-3 (SM OGG)

1E+14

To tal C-14 (SM OGG)
1E+12

Rn-2 2 2 (SM OGG)
Kr-8 1 (SM OGG)

1E+10

Kr-8 5 (SM OGG)
Ar-3 9 (SM OGG)

1E+0 8

Ar-4 2 (SM OGG)
1E+0 6

HT (GAM M ON)
C14 H4 (GAM M ON)

1E+0 4Rn-2 2 2 (a) (GAM M ON)
Rn-2 2 2 (b ) (GAM M ON)

1E+0 2

C14 O2 (GAM M ON)

1E+0 02 0 4 0 2 14 0 2 2 4 0 2 3 4 0 2 4 4 0 2 54 0 2 6 4 0 2 74 0 2 8 4 0 2 9 4 0 3 0 4 0
Y e a rs

14 CO2 (SM OGG)
14 CH4 (SM OGG)

Summary & Key issues• Potential sources of C-14 have been
identified• A model has been developed, which cancalculate a source term
• Key unresolved issues– C-14 release from irradiated materials– Carbonation– Data– Differences in software output

添付資料 3
T.Yamaguchi, S.Tanuma, H.Tanabe,
et al.,“A Study on Chemical Forms andMigration Behavior of Radio
nuclidesin Hull wastes,”

Radioactive Waste Management andEnvironmental Remediation(ICEM 1999),
Nagoya, Japan, (1999).

Radioactive Waste Management and Environmental Remediation — ASME 1999

A STUDY ON CHEMICAL FORMS AND MIGRATION BEHAVIOR OF RADIONUCLIDES IN HULL WASTES
Takashi Yamaguchi and Susumu Tanuma
Kansai Electric Power Co.
Isamu Yasutomi, Tadashi Nakayama and Hiromi Tanabe
Radioactive Waste Management Center
Kiyomichi Katsurai, Wataru Kawamura and Kazuto Maeda
Mitsubishi Heavy Industries Ltd.
Hideo Kitao and Moriyuki Saigusa
Nuclear Development Co.
ABSTRACT
A hot test using real hull was conducted, to evaluate chemical forms, migration behavior and other propertiesof C-14 and nuclides in the hull waste, with large contributions to a dose equivalent to TRU waste disposal. As aresult of hull specimen without oxide film radioactive inventory analysis, the inventory of C-14 was 9.9 x
104Bq/35mm sample (3.0 x 104 Bq/g), roughly matching ORIGEN 2 calculation results. The leaching test results
showed that the chemical forms of C-14 leached from the hull are organic and that the oxide film influences leaching speed. A study of a C-14 leaching model, based on leaching test results and reference data show a possibility ofleaching from the oxide film diffusing out. There is also a possibility of film formation after corrosion and diffusion inside the film for the leaching from base material. On the basis of this leaching scenario, an evaluation of theleaching period of C-14 was conducted.
Keywords: TRU waste disposal, hull waste, C-14, chemical form, inventory, distribution coefficient.
INTRODUCTION
In TRU waste disposal, C-14 and Cl-36 in hull waste areconsidered nuclides which contribute substantially to radiation
exposure. C-14 in particular, is considered an important nuclide
with considerable influence on disposal notion, and stability andeconomy in disposal.
However, observational data on the leaching rate of C-14 inhull waste and its distribution coefficient in barrier material havenot been obtained, resulting in a rather conservative parametersetting in safety evaluation. For this reason, the possibility of C14 or Cl-36 becoming a dominant nuclide in safety assessmentand exerting influence on the current disposal concept is now
being examined.
The purpose of this study was to contribute to the establishment of an optimum disposal concept by obtaining and evaluating
data on hull waste radiation, its leaching behavior and the distribution coefficient for cement which is an engineered barrier material.
TEST DESCRIPTIONS
Fabrication of Hull Specimens
Most of C-14 in zircaloy is generated as an activation product of nitrogen, contained as an impurity in zircaloy. [14N (n,p)
14C] There is no difference in this generation mechanism according to the type of light water reactor, so the hull specimen for the
hot test in this research was prepared from PWR spent fuel(burn-up: 47.9GWd/t).
In our hull specimen preparation method, the treatment
method of spent fuel was similar to the one in a reprocessing
plant, but there was no dissolution of fuel pellet, which was firsteliminated by a mechanical process, followed by the dissolution
and cleaning of a small amount of attached pellet powder in thesame dissolution conditions as in a reprocessing plant.
In this study, the following three types of specimen, wereprepared to examine differences in radioactive inventory andleaching behavior between zircaloy base material and oxide film:

1) Hull specimen 2) Hull specimen without oxide film 3) Oxide
film (separation treatment from hull specimen) The hull specimen
without oxide film was prepared by mechanical scraping, and theoxide film was prepared by compressing the hull specimen.
Radioactive Inventory Analysis
For conducting the analysis of radioactive inventory in hull,
the whole hull specimen was dissolved by acid, and an analysis
of nuclides in the solution and the off-gas was carried out. The
following three types of specimen were analyzed: 1) Hull specimen 2) Hull specimen without oxide film 3) Oxide film. Afterthe solution undergoes refining treatment and sodium hydrate,
which is the off-gas trap, the measurement of C-14 and Cl-36 is
conducted by beta liquid scintillation counting. The measurement of gamma-ray nuclide was conducted by a gamma spectrometry of the solution.
Leaching Test of C-14 in an Environment Simulatinga Disposal Environment
For the C-14 leaching test, the following two types of tests
were planned: 1) Short-term test focusing on grasping theleached C-14 chemical form, and 2) Long-term test focusing onleached volume. The composition of the test solution was decided from the calculation results using the geochemical calculation
code PHREEQE (2, 3) by assuming a reaction between concreteand sea-water-derived groundwater, which is considered to provide conditions for the most advanced corrosion of hull. In the
short-term test, the specimen was compressed in order toincrease the surface area to volume ratio with the purpose ofaccelerating the leaching process. This was based on the prediction that the nuclide leaching behavior from the hull waste differs from the leaching from oxide film and the leaching fromhull base material. A test was conducted on two types of specimen, the hull specimen and hull specimen without oxide film.
The test conditions are shown in Table I.

Yamaguchi

STUDY ON CHEMICAL FORMS OF RADIONUCLIDES IN HULL WASTESTABLE I
Test Parameters of the Leaching Test

Figure 1 shows the conceptual plan of the leaching test. A
stainless steel container was placed in a hot cell and the hull
specimen was put in the test container. After displacement byargon was conducted in the test container, reductant cement
equilibrium simulated groundwater prepared outside the hot cell
was poured into the test container through a tube. With the conditions of the immersion environment simulating those ofgroundwater environment, the test container was left to standand stored for a certain period of time.
From reference (4) and (5) concerning the chemical formsof C-14 released from zircaloy, there is a possibility that theleached C-14 may exist in the chemical forms of CO 2 andCO/CH4 in gas phase. Therefore, a wet analysis was conductedto judge whether the C-14 in liquid phase is organic or inorganic, as shown in the analysis flow in Fig. 2.
In this method of analysis, inorganic carbon in the sample
solution is brought into contact with inorganic acid to form carbon dioxide and discharged for a measurement as inorganic carbon. Next, oxidizing agent is added to the remaining sample tooxidize and discharge all carbon as carbon dioxide for its measurement as organic carbon. For the C-14 in gas phase, the following method was employed for separation and recovery. C-14
in CO2 form is first absorbed into sodium hydroxide solution,then C-14 in CO form is converted into CO2 by a catalyst and isabsorbed into a sodium hydroxide solution. Finally, C-14 in CH4
form is burned for conversion into CO2 and absorbed into thesodium hydroxide solution.
Obtaining Test of the Barrier Material’sDistribution Coefficient
To examine the migration behavior of leached C-14 in engineered material, an obtaining test of the distribution coefficientfor two types of cement barrier material using the leached solution obtained in the leaching test was conducted. In order to simulate the disposal environment, the test was conducted inside a
glove box controlled by argon gas-displaced atmosphere. 1L
leaching solutions were poured into polypropylene bottles, andafter the oxidation-reduction potential was lowered by iron powder, 100g of material was added and the solutions were left tostand for 7 days. After the immersing test, the solids and liquids
were separated by filtering, and an analysis of C-14 in the filtered liquid was conducted using wet analysis. The test conditions are shown in Table II.

TEST RESULTS
Radioactive Inventory
Table III shows the inventory analysis results. The volumeof C-14 in the hull specimen was 1.2 x 105Bq/35mm sample (3.2
x 104Bq/g), which matched the total of the volumes separately
analyzed for the hull specimen without oxide film and the oxidefilm, thus achieving mass balance. The C-14 volume in the oxide
film was approximately 17%.
Cl-36 was detected with a concentration lower than that of
C-14 by three digits. Among other radionuclides, the gamma
nuclides of Co-60, Cs-134, Cs-137, Eu-154, Ru-106/Rh-106 andSb-125 were detected.
Leaching Test of C-14 in a Simulated Disposal Environment
Table IV shows the results of the short-term leaching test.
The leached C-14 was not detected in the chemical form of CO2,
CO or CH4 in the gas phase, most of it in organic forms weredetected in the liquid phase. Thus, most of the leached C-14
must was presumed as organic compounds in the liquid phase.
Filtering the leached liquid with an anion filter showed that mostof the C-14 exists in the filtered liquid and that, as a result of
this, there is a possibility of C-14 existing as a substance otherthan organic acid. However, the concentration of the leached C14 was too small, with 0.1 Bq/ml, to identify the chemical
species.
Figure 3 shows the results of the long-term leaching testwith the volume of C-14 leached against time. Similar to theshort-term test, C-14 was detected in the liquid phase not in thegas phase and, most of it in organic forms. The volume of C-14
leached from a hull specimen without oxide film was one digit
less compared to C-14 leached from the hull specimen, showing
an obvious difference of the existence or absence of oxide film.
The rate at which the volume was leached decreased with time.
The leached nuclides that were detected included Co-60, Cs-134,
Cs-137, Eu-154, Ru-106/Rh-106 and Sb-125 aside from C-14,
but Cl-36 was not detected.
Conducting a Measurement Test for theDistribution Coefficient of Material
Table V shows the concentration of C-14 in the solutions
before and after the test and the distribution coefficient obtained
from the result. The distribution coefficient is expressed in thefollowing equation.

STUDY ON CHEMICAL FORMS OF RADIONUCLIDES IN HULL WASTESYamaguchi

Fig. 1. Leaching test outline diagram.

Fig. 2. Leaching test sample analysis flow.
TABLE II
Test Conditions for Obtaining Distribution Coefficient DataDISCUSSION

Kd=(Co/Ce-1) V/W
The symbols stand for the following:
Kd : distribution coefficient
Co : initial concentration of C-14 (Bq/ml)
Ce : concentration of C-14 after the test (Bq/ml)V: test solution volume (ml)W : barrier weight (g)For the distribution coefficient of C-14 for material, values
were in the range of 1.9~8.8 ml/g. There was no significant difference in distribution coefficient according to the type of material between OPC cement and 1/9 (OPC/BFS) cement. There wasalso no significant difference in the liquid leached from the hull
specimen and the hull specimen without the oxide film.

C-14 Inventory
Table VI shows the C-14 analysis values obtained as a resultof inventory analysis and C-14 calculation results by ORIGEN2. In the ORIGEN-2 calculation, the value of the impurity nitrogen, from which C-14 was generated, was calculated by thenitrogen concentration according to JIS chemical composition
standard (6) of zircaloy. It value is considered to be the maximum value of nitrogen. As a result, the values calculated fromJIS chemical composition standard values were approximately
two times as much as the inventory analysis values, and can beconsidered as conservative values in the inventory evaluation of
C-14 in hull. If the analysis value of nitrogen in zircaloy is used
to ORIGEN-2 calculation, it is estmated that the calculation
result more match the inventory result.

Yamaguchi

STUDY ON CHEMICAL FORMS OF RADIONUCLIDES IN HULL WASTESTABLE III
Inventory Analysis Results

TABLE IV
Results of the Short-term Test

Fig. 3. Change of C-14 depending on time in the long-term leaching test.
TABLE V
Results of the Distribution Coefficient Measurement Test

Chemical forms of C-14 in the Leached Liquid
The results of the leaching test, confirmed that most of the C14 released from the hull and existing in the leached liquid are inorganic forms. From a thermodynamic viewpoint, the disposal
environment has reduction atmosphere conditions with oxidationreduction potential at approximately -300mV, further it is estimated that the oxidation-reduction potential is even lower in thephase boundary in which the corrosion of zircaloy occurs, a

region where methane and methanol exist in stable forms according to the Pourbaix chart (7). Adding to this condition, there ismuch hydrogen generated from reduction condition corrosion ofZr (i.e. Zr + 2H2) → ZrO2 + 2H2). The ratio of the released number of atoms of C to H from one atom of Zr may be estimated to
be about 1 : 103 if the concentration of C in zircaloy metal is270ppm according to JIS specification. Thus, there is a high possibility that the released C-14 exist as those organic matters.

STUDY ON CHEMICAL FORMS OF RADIONUCLIDES IN HULL WASTESYamaguchi

TABLE VI
Comparison of Analysis Results with ORIGEN-2 Calculation Results

The chemical forms of C-14 in the hull is not clear, there isa possibility that it may exist in graphite or carbon compounds
forms including ZrC (zircaloy carbide). These forms are generally stable. However, there is a report that hydrocarbon compounds linking multiple carbon atoms are generated from ironcarbide in an iron / water system containing carbon (8), which
implies the possibility of carbon compounds that are containedin a metal becoming organic matters when released from themetal in a metal / water system.
The chemical forms of C-14 leached from the hull is important in determining the retention functions of the nuclide in thebarrier material.
Although the chemical species of the leached C-14 could
not be identified due to its low concentration, obtaining data
concerning the identification of its chemical species, generation
mechanism and migration in a disposal environment is considered important for the near future.
Study of the Concept of the Leaching Model
From the long-term leaching test results, the rates of leaching were evaluated for C-14 and other nuclides, resulting in a
grasp of the leaching trend of each nuclide. Figures 4 show thechange depending on time of the rate of leaching from hull specimen and from hull specimen without oxide film for eachnuclide.

The leaching rate of each nuclide is defined as follows:
R=A1/A0
R : leaching rate (-)
A1 : leached nuclide (Bq)
A0 : nuclide in hull (Bq)
Although no major difference is observed in the leaching rate
for each nuclide, leaching rate values are different for eachnuclide, which is true in hull specimen and hull specimen without
oxide film alike. Fission products (FP nuclides) such as Cs-134
and Cs-137 show a higher leaching rate than C-14, which can be
attributed to the uneven distribution due to implantation of FP
nuclides into the hull or the dissolution of nuclides attached onoxide film. On the other hand, leaching rates are lower for activation products (AP nuclides) such as Co-60 or Sb-125 than for C14. Their incorporation into the film of zirconium oxide generated with corrosion of zircaloy is a possible cause for this.
Because there were differences in leaching behavior, the‘scenario’ of C-14 from its existence inside the hull to leaching
was sorted out by identifying processes including the following
as individual scenarios: 1) diffusion in base material 2) diffusionin oxide film 3) congruent dissolution with oxide film 4) corrosion of base material → formation of oxide film 5) desorption of
attached substances From these scenarios, the leaching scenario

Fig. 4. Change depending on time of the leaching rate.

Yamaguchi

STUDY ON CHEMICAL FORMS OF RADIONUCLIDES IN HULL WASTES

of C-14 was examined, with the oxide film and base material as
the source for generation.
Using reference data (9), (10), (11) and (12), a trial calculation of the leaching volumes in these scenarios was performed
and the calculation results were compared with the long-termleaching test results, to evaluate the validity of these scenarios.
For the diffusion coefficient, temperature correction was made toreference data for conversion to values at room temperature.
Table VII shows the results of studying the validity of the leaching scenario. For the hull specimen, the degree of corrosion
influence was small, implying a possibility of the influence ofdiffusion and attached substances. The evaluation using diffusion coefficients from the reference materials by Smith, et al. (9)matched well with the test results. For the hull specimen without
oxide film, it became clear that the influence of the corrosion
scenario is extensive.
Inventory analysis results confirmed that the C-14 volume
had the same concentration as in the base material that exists inthe oxide film, there is a possibility of a mechanism in which C14 is not released immediately by corrosion but is incorporated
into the film and released by diffusion.
Based on the results of the long-term leaching test and astudy of the leaching model, the period required for all the C-14
in hull to be leached out was calculated. The results of the longterm leaching test were classified, according to the leachingvalue curve, to initial and at-equilibrium states for the purposeof evaluation. From the leaching model, it was assumed thatleaching conforms with 1/2 square-law of time for an evaluationof the base material and oxide film. From these results, it wasevaluated that a minimum period of 20,000 years or longer isrequired for all of C-14 to be released from the hull. As C-14
has a half-life of 5,730 years, it became clear that there is a pos-sibility that introducing the hull leaching model may reduce thedose equivalent of C-14. The challenge for the near future
includes obtaining test data for establishing the C-14 leachingmodel for leaching from the hull.
SUMMARY OF THE RESULTS AND CONCLUSION
1) Hull specimen was prepared from spent fuel to conduct
inventory analysis of C-14 and C1-36 and to immerse
the hull specimen in the test solution simulating groundwater for a measurement of the leaching rate and chemical forms of C-14. By using the leached solution, anabtaining test of distribution coeffieient was carried out.
2) Results of the inventory analysis of C-14 showed that
C-14 volume in hull specimen was 1.2 x 105 Bq/35mm
sample (3.2 x 104 Bq/g) and C-14 volume in oxide film
was 17%.
3) Two types of leaching tests were conducted. The shortterm leaching test and the long-term leaching test.
Most of the leached C-14 detected in the leached solution is in organic form, pointing to the need for future
research to understand its generating mechanism andmigration in barrier material. The results of the longterm leaching test made it clear that the existence orabsence of oxide film has a considerable influence onleached volume.
4) By a comparison of the leaching test results data andthe leached volume calculated from reference data, it
was assumed, as the scenarios of C-14 leaching fromthe hull, that there is a possibility of diffusion for theleaching from oxide film and a possibility of film formation after corrosion and diffusion inside the film forthe leaching from base material.

TABLE VII
Examination of the Validity of C-14 Leaching Scenarios

STUDY ON CHEMICAL FORMS OF RADIONUCLIDES IN HULL WASTES
5) Based on this leaching model, it was calculated that theperiod required to leaching all the C-14 from the hull
waste is 20,000 years or longer. This made clear the
possibility that by introducing a leaching model, a dose
equivalent of C-14 in hull waste may be reduced.
ACKNOWLEDGEMENT
This research was funded by the Japanese electric utilities
and Japan Nuclear Fuel Limited.
REFERENCES
1. PNC, ‘Technical Report of Research and Development in
High-Level Waste Geological Disposal, 1991 Report’
2. A. ATKINSON et al., ‘Evolution of pH in a Rodwaste
Repository: Experimental Simulation of Cement Leaching,’
DOE/RW/89/025
3. E.J. REARDON, ‘Problems and Approaches to thePrediction of the Chemical Composition in Cement/Water
System’
4. LOIS et al., ‘Investigations Into the Chemical Status of C14 After Leaching of Cladding Material From Spent PWR

Yamaguchi

and BWR Fuel Rods in a Salt Solution,’ SIEMENS
U9414/88/001 (Apr.1988)
5. JAERI-M, 83-035
6. JIS H 4751 (1990)
7. MARCEL POURBAIX, ‘Atlas of Electrochemical
Equilibria in Aqueous Solutions’
8. BAOLIN DENG et al., ‘Hydrocarbon Formation in Metallic
Iron/Water System,’ Environ.Sc.Technol., 1997, 31.11851190
9. H.D. SMITH et al., ‘An Investigation of Thermal Release of
Carbon 14 From PWR Zircaloy Spent Fuel Cladding,’
Journal of Nuclear Materials, 200(1993) 128-137
10. Japan Metal Society, ‘Metal Data Book,’ 1984
11. C.M. HANSSON, ‘The Corrosion of Zircaloy — 2 inAnaerobic Synthetic Cement Pore Solution,’ SKB/KBS
Technical Report, 84-13 (Dec.1984)
12. G. PLANTE et al., ‘Etudes de Corrosion des Materiaux deConteneuers Pour le Stockage des Dechets Radioactifs enSites Granitiques,’ Communautes Europeennes, EUR8762FR (1984)

添付資料 4
S.Kaneko, H.Tanabe, M.sasoh, et al.,“A Study on the Chemical Forms andMigration Behavior of Carbon-14
Leached from the Simulated Hull
Waste in the Underground condition,”Mat. Res. Soc. Symp. Proc. Vol.757,
p.621-p.626, (2003).

2002 MRS FALL MEETING
December 2-6 BOSTON, MA
A Study on the Chemical Forms and Migration Behavior of Carbon-14 Leached from theSimulated Hull Waste in the Underground condition
Satoru Kaneko*, Hiromi Tanabe*, Michitaka Sasoh**, Ryota Takahashi**, Takayuki Shibano**,Shinji Tateyama***Radioactive Waste Management Funding and Research Center, 2-8-10 Toranomon Minato-ku,
Tokyo 204-0001, JAPAN**Toshiba Corporation, 4-1 Ukishima-cho Kawasaki-ku, Kawasaki, 210, JAPANABSTRACTThe chemical forms of carbon leaching from carbon-containing Zr and Fe-based metallic
materials have been investigated to improve the estimation of the contribution of C-14 in theperformance assessment of TRU waste disposal. Both organic and inorganic carbons wereidentified in the leached solution with carbon containing zirconium and steel, and theconcentrations of total carbon (organic plus inorganic) in the leached solutions increased withtime. The carbon concentrations in the leached solution for both metallic samples were higher athigher pH. With High Performance Liquid Chromatography (HPLC), organic carbons wereidentified to be low-molecular weight alcohols, carboxylic acids and aldehydes.
To explore the chemical state of carbon in the matrix materials, the leaching experiments
were carried out also for ZrC, Fe3C, the powder mixtures of carbon and zirconium, and of carbon
and iron. The low-molecular weight organic carbons were detected only in the case of carbides(ZrC and Fe3C). The chemical forms of carbon in the zirconium alloy were suggested to be
carbide or carbon by H.D.Smith[1]. The present result suggests that the chemical forms of carbon
in zirconium or iron are mainly in the form of carbide.
In the interest of performance assessment, the distribution coefficients of the organiccarbon species identified in the leached solution for cement were obtained. As expected, some ofthem were shown to be larger than the values assumed in the performance assessment of Progress
Report on Disposal Concept for TRU Waste in Japan[2].
INTRODUCTION

In the performance assessment of transuranic (TRU) waste disposal, from the Nuclear
Fuel Reprocessing Facility, carbon-14 (C-14) in the hull (zircaloy cladding waste) and end pieces
has been so far estimated to considerably contribute to the radiation exposure to the public[2]. In
this performance assessment, however, the estimation is based on the fairly conservatively
1

2002 MRS FALL MEETING
December 2-6 BOSTON, MA
selected parameters for C-14, since the chemical forms of C-14 leaching from the hull areunknown[3]. For the performance assessment to be more realistic, the chemical forms of C-14
leaching from the hull should be identified. For example, the distribution coefficients of C-14 forbarrier materials, example cement, bentonite and so on, would be low, if the form of C-14 ismainly organic. Thus, the chemical forms of carbon leaching from carbon-containing Zr andFe-based metallic materials have been investigated to improve the estimation of the contributionof C-14 in the performance assessment of TRU waste disposal. To support the discussion for the
speciation of C-14 in the leached solution, the leaching experiments were also carried out for ZrC,
Fe3C, the powder mixtures of carbon and zirconium, and of carbon and iron. Based on this result,the distribution coefficients of some organic carbon species identified in the leached solution for
cement were carried out in this study.
EXPERIMENT
Table 1: HPLC measurement System
Measurement conditions

Leaching experiment

ColumnRspax KC-811*2

Mobile phase

１ｍM HClO4

In the leaching experiments, zirconium
Flow rate
0.8ml/minpowder (carbon content: 0.02wt.%) and carbon steel
Column temperature
40℃
cutting powder (carbon content: 0.12wt.%) were used
UV detector
to simulate hull and end pieces[4]. These kinds ofWavelength
210nm
metallic powder were immersed in solutions of the
Response
SLOW
pH adjusted to 8 or 12.5 using NaOH (sodium
Output0.001AU/mVRI detectorhydroxide) solution. The liquid-to-solid ratio of
Polarity＋
experimental samples is 1ml/g. These samples were
Response
SLOW
kept in a glove box under reducing atmosphere.
Output0.5*10-6RIU/10mV
Sampling of the solutions was conducted at regular
Injection
100µｌintervals, and the concentrations of total carbon,
organic carbon and inorganic carbon were measured
using a continuous total organic carbon analyzer (TOC analyzer SHIMADZU Co. Ltd. Model
5000 A)[5]. High performance liquid chromatography (HPLC) was also carried out for thesolution samples to identify the organic carbon compounds. The conditions and the equipments
for the HPLC analysis are shown in Table 1.
To examine the mechanism of the releasing process of carbon compounds fromzircaloy and steel, the leaching experiments were also conducted with using ZrC, Fe3C, themixture of carbon powder and Zr powder, the mixture of carbon powder and Fe powder as thesolid phase. The experimental conditions, pH and liquid-to-solid ratio and the surrounding2

2002 MRS FALL MEETING
December 2-6 BOSTON, MA
atmosphere were the same as in the leaching experiment for metallic powder.
Sorption ExperimentHydrated ordinary portland
Table 2: Measurement conditions of distribution coefficient values
cement was used in the experiment
Solid phase
OPC
to obtain the sorption distribution
Liquid phase
Purified water
coefficeints of the organic carbon
Solid particle diameter
250 micrometer or lessspecies identified in the leached
Liquid-to-solid ratio
10ml/gsolution for cement. After pH of
The organic
Methanol、Ethanol、Formaldehyde、
the solution was adjusted tomaterials covered
Formic acid、Acetic acidaround12.5
withsodiumConcentration ofhydroxide, the solutions were10ppm
organic materials
contacted with the powdered
Temperature
Room temperature
hydrated
cement(<250
micrometer) at a ratio of 40 cm3 toReducing atmosphere (in a glove
Atmosphere
4 g. After 100 days the solutions
box of 3%nitrogen-hydrogen)were
filteredthrough0.45-micrometer
filter.
All
operations for this experiment were performed inside glovebox. The detailed parameters for theexperimental condition are listed in Table 2.
RESUTS & DISCUSSION

The changes over time in the concentration of organic and inorganic carbon in theleaching experiments for carbon steel and zirconium powder are shown in Figures 1 and 2
respectively. It is clear from these figures that the carbon concentration became constant for after
approximately five months of leaching in the solution. In both leaching experiments of carbon
steel and zirconium, the existence of inorganic carbon species were confirmed as well as organiccarbon. Also, regarding the leaching tendency of carbon, it was discovered that the higher the pH,
the greater the amount of carbon leached into solution.
Figure 3 shows the changes over time in carbon concentration, total organic carbon
concentration and inorganic carbon concentration for ZrC and Fe3C.
Similarly to the cases of carbon steel and zirconium, the results indicate that the
inorganic carbon exists as well as organic carbon, and that the amount of carbon leached into
solution is greater at higher pH.
3

2002 MRS FALL MEETING
December 2-6 BOSTON, MA
In the Liquid Chromatograms(HPLC), organic carbon species were identified as
low-molecular weight alcohols, carboxylic acids and aldehydes. The identified carboxylic acids
were formic acid (HCOOH) and acetic acid (CH3COOH) from HPLC, and the aldehyde wasformaldehyde (HCHO). Methanol (CH3OH) and ethanol (C2H5OH) were confirmed.
40

40

Carbon steel cutting powder (pH8)

Carbon steel cutting powder (pH8)35

Carbon steel cutting powder (pH12.5)

Carbon steel cutting powder (pH12.5)

30

Zr powder (pH12.5)

Zr powder (pH8)30

Zr powder (pH8)

Zr powder (pH12.5)

25

IC concentration (ppm)

TOC concentration (ppm)

35

20
15

25

20

15

10

10

5

5

0

0
0

2

4

6

8

10

12

14

16

0

18

2

4

6

8
10
Reaching time （month）

12

14

16

Reaching time （month）

Figure1: The total organic carbon concentration

Figure2:The inorganic carbon concentrationleached from Zr and Carbon steel

leached from Zr and Carbon steel

250

250

ｐＨ：８．０(1month)

ｐＨ：８．０(1month)

ｐＨ：１２．５(1month)

ｐＨ：１２．５(1month)

ＴＯＣ concentration (ppm)

ｐＨ：８．０(3months)

ｐＨ：１２．５(3months)

150

100

200

ｐＨ：８．０(3months)

ｐＨ：１２．５(3months)
ＩＣ Concentration (ppm)

200

150

100

50

50

0

0
ZｒC

Fe3C

C
Sample

Zｒ+C

ZｒC

Fe+C

Total organic carbon concentaration from carbaides

Fe3C

C
Sample

Zｒ+C

Fe+C

Inorganic carbon concentaration from carbaides

Figure 3: The carbon concentration leached from carbides

From the leaching experiments for ZrC, Fe3C, the mixture of carbon powder and Zr
powder, the mixture of carbon powder and Fe powder, the low molecular weight organic carbon
was detected only in the case of carbide (ZrC and Fe3C). Figure 4 and 5 show the results ofidentification by HPLC for leaching experiments of metallic powders and carbides. These figures4

18

2002 MRS FALL MEETING
December 2-6 BOSTON, MA
confirm that most of the organic carbon obtained from the leaching tests of the metal samples andcarbides were carboxylic acids.

1
Ratio of Organics
Compounds

Ratio of Organics
Compounds

1

0.5

0

CarbonSteel(ｐH8)

Fe3C(ｐH8)

Fe+C(ｐH8)

CarbonFe3C(ｐH12.5) Fe+C(ｐH12.5)
Steel(ｐH12.5)

0.5

0 Zr Powder(ｐH8)

Leaching Condition (Fe)Calboxylic Acids

Aldehydes

Alcohols

ZrC(pH8)

Zr+C(ｐH8)

Zr Powder(ｐH12.5)

ZrC(ｐH12.5)

Zr+C(ｐH12.5)

Leaching Condition (Zr)e.t.c

Calboxylic Acids

Aldehydes

Alcohols

e.t.c

Figure 4: The Ratio of Organics Compounds in

Figure5: The Ratio of Organics Compounds in Leaching

Leaching Solution for Carbon Steel, Fe3C

Solution for Zirconium ,ZrC and The Mixture of Zirconium

and the mixture of Iron and Carbon

and Carbon

Although the chemical forms of the carbon contained in metals are still unknown, H. D.
Smith et al. suggested that carbon exists in the form of carbides or atomic carbon in zircaloy. If
the carbon in metallic matrix is carbide, it is thought that the generation of organics in theleaching solution causes from carbides reaction with water such as hydrolysis of zirconium
carbide. In the case of atomic carbon, the organic carbon species should result from the reductionof carbon with oxidizing metal to its oxides. In the present study, when considering the fact thatthe main organic carbon compounds obtained from the leaching experiments of metal samples arecarboxylic acids and that most of the organic carbon compounds whose existence is confirmed in
the leaching experiments of carbides are carboxylic acids, it is implied that one of the chemical
forms of carbon in metals could be carbide.
Sorption experiment was conducted for some organics to cement materials. We used the fiveorganic carbon compounds (methanol, ethanol, formaldehyde, formic acid and acetic acid) fromthe leaching experiments. The distribution coefficients of the organic compounds for cement are
shown in Table 3. The distribution coefficient is calculated using the following formula.
The distribution coefficient =(C0-Cf)／Cf)・V/ｍ
C0：The concentration of organic compound in initial liquid phase
Cf：The concentration of organic compound in fainal liquid phase5

2002 MRS FALL MEETING
December 2-6 BOSTON, MA
m：Solid quantity〔g〕、V：Liquid volume〔L〕
These distribution coefficient values of around 10ml/g for the distribution coefficients oforganic carbon compounds are larger than the values used in the performance assessment in the
Progress Report on the Disposal Concept of TRU Waste in Japan, where the conservative values
were selected due to the insufficient knowledge on the carbon speciation.
Table 3: The Distribution coefficient values of Organic Compounds for
Ordinary Portland Cement
Organic Compound

Distribution coefficient (ml/g)

Methanol

7.2

Ethanol

12

Formaldehyde

10

ormic acid

4.1

Acetic acid

9.5

CONCLUSIONSThe leaching experiments of C-14 with carbon-containing Zr and Fe-based metallic
materials have been carried out under reducing condition. Main compounds of the organic carbon
leached from metals are carboxylic acids. According to the comparison of the result with thoseobserved in the leaching experiment with ZrC, Fe3C, the powder mixtures of carbon andzirconium, and of carbon and iron, the chemical form of carbon in the metal matrices may bemainly carbides. Furthermore, it was confirmed that the cement distribution coefficients of theorganic carbon compounds identified in the leached solutions from the metals were confirmed tobe higher than those currently used in the Japanese performance assessment of TRU waste
disposal
REFERENCES
1.

H.D.Smith, D.L.Baldwin, An Investigation of Thermal Release of Carbon-14 from PWR
Zircaloy Spent Fuel Cladding, Journal of Nuclear Material 200(1993)128-137

2.
3.

JNC.FEPC, Progress Report on Disposal Concept for TRU Waste in Japan, (Mar.2000)
T.Yamaguchi, S.Tanuma, A Study on Chemical forms and Migration Behavior of62002 MRS FALL MEETING
December 2-6 BOSTON, MA
Radionuclides in HULL Waste, ISEM1999
4. Methods for determination of carbon in zirconium and zirconium alloys, JIS,H1663,1988
5. Testing methods for total organic carbon in highly purified water, JIS,K0551,1994

7【問合せ先】〒１０５−０００１ 東京都港区虎ノ門２丁目８番１０号（第１５森ビル４階）
財団法人 原子力環境整備促進・資金管理センター（原環センター）
電話 03-3504-1081 ファックス 03-3504-1297
Radioactive Waste Management Funding and Research Center(RWMC)
No.15. Mori Bldg, 2-8-10, Toranomon, Minato-ku, Tokyo, 105-0001, Japan