本レポートは独立行政法人日本原子力研究開発機構が不定期に発行する成果報告書です。 本レポートの入手並びに著作権利用に関するお問い合わせは、下記あてにお問い合わせ下さい。 なお、本レポートの全文は日本原子力研究開発機構ホームページ（http://www.jaea.go.jp） より発信されています。

独立行政法人日本原子力研究開発機構 研究技術情報部 研究技術情報課 〒319-1195 茨城県那珂郡東海村白方白根 2 番地 4 電話 029-282-6387, Fax 029-282-5920, E-mail:ird-support@jaea.go.jp

This report is issued irregularly by Japan Atomic Energy Agency Inquiries about availability and/or copyright of this report should be addressed to Intellectual Resources Section, Intellectual Resources Department, Japan Atomic Energy Agency 2-4 Shirakata Shirane, Tokai-mura, Naka-gun, Ibaraki-ken 319-1195 Japan Tel +81-29-282-6387, Fax +81-29-282-5920, E-mail:ird-support@jaea.go.jp

© Japan Atomic Energy Agency, 2008

2008 8 7

17

1

100kg

10

Ge

1

Bq/cps Ge cps

(Bq)

(Bq)

100kg Bq/g

1

319-1195 2-4

*1 ( )

*2

�����������������������

�

100kg

2

1/10

EGS5

�����������������������

�

Clearance Assessment for Building Concrete through Bulk In-situ -spectrometry

(Contract Research)

Shingo MAEDA*1, Takahiro HIRANO*2, Taro SHIMADA and Shinichi NAKAYAMA

Nuclear Facility Safety Research Unit

Nuclear Safety Research Center

Japan Atomic Energy Agency

Tokai-mura, Naka-gun, Ibaraki-ken

Received August 7, 2008

The regulation for the clearance of radioactive material from the regulatory control under the "Law for

the Regulations of Nuclear Sources Material, Nuclear Fuel Material and Reactors" requires that the weight

“unit” (clearance unit) of the material to be evaluated be in the order of “tons”, and that measurement

should be carried out for the part of the material of around 100kg. This 100 kg is referred to as

“measurement unit” here. The second requirement is to ensure radioactive contamination shows uniformity

on the surface of the concrete, that is, the concentrations of radionuclides in the "measurement unit do not

exceed the values of ten times of the clearance levels".

Bulk in-situ -spectrometry has been established to measure a large surface for the purpose of clearance.

This measurement is effective for a slightly and uniformly contaminated surface such as a room surrounded

by concrete walls. The time-consuming scoping scanning survey for the entire surface is essential to ensure

the slight and uniform contamination prior to the bulk in-situ measurement. However, the scoping scanning

survey is omissible if the following conservative procedure is acceptable.

1) Radioactive point source is assumed to be situated at the furthest point within the clearance unit from

the radioactivity detector.

2) The radioactivity conversion factor, Bq/cps, is known which depends on the distance from the center

edge of detector to the furthest point.

3) The count rate, cps, for the material of interest can be obtained by in-situ Ge detector.

4) Radioactivity, Bq, from the counting rate, cps, can be calculated by using the radioactivity conversion

factors, Bq/cps.

This study was conducted during 2001 through 2006 under contract with Ministry of Economy, Trade and Industry.

*1 KONOIKE CONSTRUCTION CO., LTD.

*2 HOKKO ELECTRONICS CO., LTD.

�����������������������

�

�����������������������

5) The radioactive concentration, Bq/g, is evaluated by dividing the radioactivity 4) by the "measurement

unit" of 100kg.

This procedure could certainly produce a conservative value, because the radioactive contamination

assessed conservatively through 1) above is divided by not 1 ton but a smaller weight of 100 kg. If the

value obtained by this procedure is lower than the regulated clearance level, the material of interest can be

cleared without the prior scoping scanning survey.

Since the procedure deals with very low radioactive concentration, the applicability was tested in a

real-sized concrete-wall room through measurement using portable Ge detector and numerical analysis by

Monte Carlo Code (EGS5), to ensure that the measurement can be completed within a reasonable surface

area and period of measuring time.

Keywords: Clearance, Building Concrete, Portable Germanium Detector, Bulk In-situ -spectrometry, EGS5

�����������������������

�

1 1

2 3

2.1 3

2.2 3

2.3. 6

3 9

3.1 9

3.2 9

4 11

4.1 11

4.1.1 11

4.1.2 13

4.2 14

4.3 Ge 14

5 15

16

16

�����������������������

�

Contents

1. Introduction ········································································································································· 1

2. Background of this study ····················································································································· 3

2.1 Outline of bulk in-situ -spectrometry······························································································ 3

2.2 Previous study································································································································· 3

2.3 Current regulation for clearance of material from regulatory control ··············································· 6

3. Fundamental concept of proposed method of bulk in-situ -spectrometry for building concrete ·········· 9

3.1Issues of bulk in-situ -spectrometry······························································································· 9

3.2 Fundamental concept of proposed method of bulk in-situ -spectrometry for building concrete ···· 9

4. Study of the method of bulk in-situ -spectrometry············································································ 11

4.1 Applicability assessment of the method to actual facility······························································· 11

4.1.1 Effects of judgmental value of clearance and dimension of the room to measurement time ······ 11

4.1.2 Effects of natural radionuclide concentration to measurement time ·········································· 13

4.2 Important reminder for application of this method ········································································ 14

4.3 Efficient measurement using in-situ Ge semiconductor detector ···················································· 14

5. Concluding remarks··························································································································· 15

Acknowledgement································································································································· 16

Reference ·············································································································································· 16

�����������������������

�

2.1

2.2 Ge

4.1

4.2 EGS5

4.3

4.4

4.5

4.6 ) 60Co(1173.2keV)

2.1

2.2

2.3

2.4

2.5

3.1

4.1

4.2 60Co

4.3 60Co(1173.2keV)

4.4 60Co(1173.2keV)

4.5 EGS 60Co(1173.2keV)

4.6 EGS 60Co(1332.5keV)

4.7 EGS 60Co(1173.2keV)

4.8 Ge

2.1 45°

2.2

4.1 1

4.2 2

�����������������������

�

Tables Figures and Photos Captions

Table 2.1 Standards and specifications of measurement equipment

Table 2.2 Test condition for characterization of directions of in-situ Ge detector

Table 4.1 Dimension and structure of area room

Table 4.2 Radioactivity conversion factors for types of rooms

Table 4.3 List of calculated measurement time and efficiency

Table 4.4 Concentration of natural radionuclides existing in building concrete

Table 4.5 Natural radionuclides used for calculation

Table 4.6 Comparison of minimum counting rate between max and average of concentration60Co(1173.2keV)

Fig. 2.1 Schematic view of bulk in-situ -spectrometry for building concrete

Fig. 2.2 Composition of equipment

Fig. 2.3 Schematic view of characterization test for direction dependence of detector

Fig. 2.4 Results of test for direction dependence

Fig. 2.5 Flow chart for selection of measurement method for secondary contamination (for large area)

Fig. 3.1 One example of clearance judgment’s flow chart

Fig. 4.1 Ex-area for melting test in the Backend Technique Development Building

Fig. 4.2 Temporal change of minimum detection counting rate for 60Co

Fig. 4.3 Measurement time for each type of room in case of focusing on 60Co(1173.2keV)

Fig. 4.4 Measurement efficiency for each type of room in case of focusing on 60Co(1173.2keV)

Fig. 4.5 Comparison of experimental data and calculation results, 60Co(1173.2keV)

Fig. 4.6 Comparison of experimental data and calculation results, 60Co(1332.5keV)

Fig. 4.7 Comparison of calculated results between max and average concentration of natural radionuclides, 60Co(1173.2keV)

Fig. 4.8 Schematic view of measurement method for in-site Ge detector

Photo 2.1 Conditions of characterization test for direction dependence of detector (45° in source positional

angle)

Photo 2.2 Conditions of characterization test for direction dependence of detector (installation of

radioactive source)

Photo 4.1 Conditions of measurement for background (No. 1)

Photo 4.2 Conditions of measurement for background (No. 2)

�����������������������

�

- 1 -

1.

17 51) 11

112

61 2 41)(

)

( ) 18 6

9

2000

19 4 107

5 107

2)

1 3)

90%

4)5)6) Ge

�����������������������

���

Ge

�����������������������

���

2.

2.1

(1)

Ge

2.1

2 2

Ge

(2) Ge

Ge60Co 2.1

2.2 2.2

2.3 Ge 1m

0 15

180 60Co

2.1 2.2

0 60Co 60Co60Co 1173.2keV 1332.5keV 2.4

0 60Co 0 150

2 90% Ge

150 60Co

Ge

2.2

(1) ( )

2005

4)

NUPEC DIN

�����������������������

���

- 4 -

-NUPEC DIN

2.5

Ge

100cm2 1m2

( )7) NUPEC

NUPEC

5cm

(2) ( ) (NUPEC)

NUPEC

8 125

Ge

0.1Bq/cm2 100cm2 30Bq/100cm2

1m 1m (Bq/cm2) (Bq/g)

5mm 10mm 2

1kBq/m2 0.1Bq/g 0.05Bq/g60Co 137Cs

0.1Bq/g 4)

50mm

NUPEC 5

10137Cs

�����������������������

���

- 5 -

1m 1m 1m 1m137Cs

1m 1m

5m 5m 5m 150m2

0.01kBq(60Co)/m2 1.5

1m 1m

1kBq(60Co)/m2 15

30Bq/100cm2

10cm 10cm

5)

120% Ge

(3) ( )

NUPEC 13

7)

Ge

15m 4.5m 5.8m

)/())//((

)( gBqRgBqcps

cps

R 32cps/(Bq/g)60Co 0.1Bq/g

3.2cps 40K

2.0cps 60Co

3.2cps

�����������������������

���

- 6 -

Ge 120%

12.8cps/(0.4Bq/g)for 60Co

32cps/[Bq/g] ( =12.8 0.4 )

60Co 60Co 0.39Bq/g

1/2 0.19Bq/g

12.48cps

12.48 2=6.2cps

1000 0.064cps 0.002Bq/g (=0.064cps 32cps/(Bq/g))

3

110m2

0.064cps

0.064cps<6.2cps

2.3

1.

17 5 11

�����������������������

���

- 7 -

NISA 18 1

6

NISA

NISA 6 2

6 2

6 2

6 61 2 2

2

NISA

2. 6 2

6 2

100kg

10

1

1

1 IAEA RS-G-1.7

10

1

100kg

10

1

10

�����������������������

���

- 8 -

10

2

NISA 1

100kg 1

1/10 100kg

100kg

10 1 10

100kg

2.2

3. 6 3

(1) 6 3

5cm

5cm 100kg

2.3g/cm3 8696cm2 90cm

1 =1000kg 86956cm2 295cm

�����������������������

���

3.

3.1

2.3

Ge

2 Ge 1

3.2

Bq/g

Bq/cps Bq/g/cps

1

Bq/cps cps

Bq

Bq/g Bq

NISA 100kg

(D) (C)

D/C 1

�����������������������

���

cps Bq

100kg

100kg

100kg NISA

1 100kg

1/10

1

3.1

Ge

�����������������������

����

4.

3.

EGS5

40K

2 EGS5

Ge

60Co

4.1

4.1.1

(1)

2.3

NISA 10t 1

3m

10ton

2.3g/cm3 2.3 t 5cm

4.1

(2)60Co

4.1

4.1 4.2

300 60Co

�����������������������

����

1173.2keV 1332.5keV

Cooper 8)

4.2

1173.2keV 1332.5keV

509.0d t995.1N:keV5.1332

498.0d t514.2N:keV2.1173

Nd (cps) t (sec) 1173.2keV

1332.5keV40K( 1460.6keV) 1332.5keV

1173.2keV60Co

1173.2keV

(3) EGS5 Bq/cps60Co 4.1 2m 7m Ge

EGS5 (Bq/cps)

4.2 2.1 60Co

(4)60Co 10 60Co (0.1Bq/g)

1/10 1

1 60Co

NISA 100kg

100kg (3)

(Bq/cps) (2)60Co

�����������������������

����

4.3

1173.2keV 4.3 4.4

24 0.07Bq/g

7m

0.05Bq/g 7m 6m

0.02Bq/g 2

4.1.2

EGS5

2.2 NUPEC

4.4

EGS5 60Co

3 60Co

4.560Co

4.5 4.6 1173.2keV 1332.5keV

60Co(1173.2keV) 4.7 4.6

�����������������������

����

/ 2 2

24

4.2

4.3 Ge

1

4.8 1

�����������������������

����

5.

- (1)

(2)

2 Ge 1

-

EGS5

60Co 7m 7m 3m

12

- EGS560Co

- Ge

Ge

�����������������������

����

- 16 -

1) 2006 2005 11

2) ( )

16 12 9

3) ( )

16 9 14

4) ( ) 2005 2005 6

5) ( ) -

4 15

6) ( ) 2006

10

7) ( ) 13

( 1 ) -

14 3

8) Cooper, J. A. Nucl. Instr. Methods 82 p.273 1970

�����������������������

����

2.1

Ge CANBERRA

GC30187935SL-7 S/N:01027469FWHM@1.33MeV 1.8keV FWHM@122keV 1.0keV

/ 58 130%

SEIKOEG&G

MCA 7600 ( LCD

) CPU

PHA ( Ge )5kV POS/NEG 0~5000V( 100 A)PC USB

EPSON

Endeavor NT6000

2

2.2 Ge

ls s

Co-60 36,220Bq 1m 0° 180°(15° 600

ls ;

s ( 0°

�����������������������

����

4.1

× lsmax(m) (t)

2m (2m×2m)×3m 2.06 1.8

3m (3m×3m)×3m 2.60 3.1

4m (4m×4m)×3m 3.20 4.6

5m (5m×5m)×3m 3.84 6.3

6m (6m×6m)×3m 4.50 8.3

7m (7m×7m)×3m 5.17 10.5

lsmax(m)

4.2 EGS5

2m 1.29E+05 1.35E+05 1.42E+05 1.54E+05

3m 2.03E+05 2.22E+05 2.26E+05 2.41E+05

4m 3.06E+05 - 3.39E+05 -

5m 4.38E+05 - 4.91E+05 -

6m 6.02E+05 - 6.72E+05 -

7m 8.03E+05 8.58E+05 9.01E+05 8.57E+05

60Co(1332.5keV)

(Bq/cps)60Co(1173keV)

�����������������������

����

4.3

60Co(1173keV) 60Co(1332.5keV) 60Co(1173keV) 60Co(1332.5keV) 60Co(1173keV) 60Co(1332.5keV)2m 16 7.76E-03 7.02E-03 3.05E+01 1.76E+01 0.52 0.913m 27 4.92E-03 4.43E-03 7.61E+01 4.35E+01 0.35 0.624m 40 3.26E-03 2.95E-03 1.74E+02 9.66E+01 0.23 0.415m 55 2.28E-03 2.04E-03 3.57E+02 2.00E+02 0.15 0.286m 72 1.66E-03 1.49E-03 6.74E+02 3.70E+02 0.11 0.197m 91 1.25E-03 1.11E-03 1.20E+03 6.58E+02 0.08 0.142m 16 1.55E-02 1.40E-02 7.59E+00 4.51E+00 2.11 3.553m 27 9.85E-03 8.85E-03 1.89E+01 1.12E+01 1.43 2.424m 40 6.53E-03 5.90E-03 4.32E+01 2.48E+01 0.93 1.625m 55 4.56E-03 4.07E-03 8.87E+01 5.12E+01 0.62 1.076m 72 3.32E-03 2.97E-03 1.68E+02 9.50E+01 0.43 0.767m 91 2.49E-03 2.22E-03 2.99E+02 1.69E+02 0.30 0.542m 16 2.33E-02 2.11E-02 3.36E+00 2.03E+00 4.76 7.873m 27 1.48E-02 1.33E-02 8.39E+00 5.03E+00 3.22 5.374m 40 9.79E-03 8.85E-03 1.91E+01 1.12E+01 2.09 3.585m 55 6.84E-03 6.11E-03 3.93E+01 2.31E+01 1.40 2.386m 72 4.99E-03 4.46E-03 7.42E+01 4.28E+01 0.97 1.687m 91 3.74E-03 3.33E-03 1.32E+02 7.61E+01 0.69 1.202m 16 3.10E-02 2.81E-02 1.89E+00 1.15E+00 8.47 13.853m 27 1.97E-02 1.77E-02 4.71E+00 2.86E+00 5.74 9.444m 40 1.31E-02 1.18E-02 1.07E+01 6.34E+00 3.72 6.305m 55 9.12E-03 8.14E-03 2.21E+01 1.31E+01 2.49 4.196m 72 6.65E-03 5.95E-03 4.16E+01 2.43E+01 1.73 2.967m 91 4.98E-03 4.44E-03 7.43E+01 4.32E+01 1.23 2.102m 16 3.88E-02 3.51E-02 1.21E+00 7.45E-01 13.27 21.473m 27 2.46E-02 2.21E-02 3.01E+00 1.84E+00 8.98 14.634m 40 1.63E-02 1.47E-02 6.87E+00 4.09E+00 5.83 9.775m 55 1.14E-02 1.02E-02 1.41E+01 8.48E+00 3.90 6.496m 72 8.31E-03 7.44E-03 2.66E+01 1.57E+01 2.71 4.587m 91 6.23E-03 5.55E-03 4.75E+01 2.79E+01 1.92 3.262m 16 4.65E-02 4.21E-02 8.36E-01 5.21E-01 19.13 30.723m 27 2.95E-02 2.66E-02 2.08E+00 1.29E+00 12.95 20.944m 40 1.96E-02 1.77E-02 4.76E+00 2.86E+00 8.40 13.985m 55 1.37E-02 1.22E-02 9.77E+00 5.92E+00 5.63 9.286m 72 9.97E-03 8.92E-03 1.85E+01 1.10E+01 3.90 6.567m 91 7.48E-03 6.66E-03 3.29E+01 1.95E+01 2.77 4.672m 16 5.43E-02 4.91E-02 6.14E-01 3.85E-01 26.07 41.583m 27 3.45E-02 3.10E-02 1.53E+00 9.53E-01 17.65 28.344m 40 2.28E-02 2.06E-02 3.49E+00 2.11E+00 11.45 18.925m 55 1.60E-02 1.43E-02 7.17E+00 4.38E+00 7.67 12.576m 72 1.16E-02 1.04E-02 1.35E+01 8.11E+00 5.32 8.887m 91 8.72E-03 7.77E-03 2.41E+01 1.44E+01 3.77 6.322m 16 6.21E-02 5.62E-02 4.69E-01 2.96E-01 34.09 54.043m 27 3.94E-02 3.54E-02 1.17E+00 7.33E-01 23.08 36.834m 40 2.61E-02 2.36E-02 2.67E+00 1.63E+00 14.97 24.595m 55 1.82E-02 1.63E-02 5.48E+00 3.37E+00 10.03 16.336m 72 1.33E-02 1.19E-02 1.04E+01 6.24E+00 6.95 11.547m 91 9.97E-03 8.88E-03 1.85E+01 1.11E+01 4.93 8.212m 16 6.98E-02 6.32E-02 3.71E-01 2.35E-01 43.18 68.113m 27 4.43E-02 3.98E-02 9.23E-01 5.82E-01 29.24 46.424m 40 2.94E-02 2.65E-02 2.11E+00 1.29E+00 18.97 30.995m 55 2.05E-02 1.83E-02 4.33E+00 2.67E+00 12.71 20.586m 72 1.50E-02 1.34E-02 8.17E+00 4.95E+00 8.81 14.547m 91 1.12E-02 9.99E-03 1.46E+01 8.79E+00 6.24 10.352m 16 7.76E-02 7.02E-02 3.00E-01 1.91E-01 53.36 83.763m 27 4.92E-02 4.43E-02 7.47E-01 4.73E-01 36.13 57.094m 40 3.26E-02 2.95E-02 1.71E+00 1.05E+00 23.43 38.125m 55 2.28E-02 2.04E-02 3.50E+00 2.17E+00 15.70 25.326m 72 1.66E-02 1.49E-02 6.62E+00 4.03E+00 10.88 17.897m 91 1.25E-02 1.11E-02 1.18E+01 7.15E+00 7.71 12.73

(m2/h)(m2)

0.08

0.09

(Bq/g)

0.01

0.02

0.03

0.1

0.04

0.05

0.06

0.07

�����������������������

����

4.4

40K 0.61 1.22

238U 0.052 0.081

232Th 0.022 0.048

(Bq/g)

�����������������������

����

4.5

E(MeV)40K 1.4608 0.107 1238U 226Ra 0.18599 0.0328 1

214P 0.05323 0.0105 0.99980.24198 0.0684 0.99980.29521 0.179 0.99980.35192 0.343 0.99980.78591 0.0102 0.9998

214Bi 0.60931 0.426 0.9990.76836 0.0464 0.9990.80617 0.0115 0.9990.93406 0.0295 0.9991.12029 0.139 0.9991.15519 0.016 0.9991.23811 0.0551 0.9991.28096 0.0141 0.9991.37765 0.0378 0.9991.40105 0.0133 0.9991.40798 0.0236 0.9991.50923 0.0204 0.9991.66128 0.0107 0.9991.7296 0.0268 0.999

1.76449 0.146 0.9991.84742 0.0193 0.9992.11855 0.0108 0.9992.20419 0.0459 0.9992.44778 0.0141 0.999

232T 228Ac 0.1291 0.0293 10.2094 0.0455 10.2703 0.0377 1

0.328 0.0366 10.3384 0.12 1

0.463 0.0464 10.7948 0.0484 10.9111 0.29 10.9646 0.0545 10.9689 0.1746 11.5879 0.0371 1

212Pb 0.23862 0.431 10.30009 0.033 1

212Bi 0.03986 0.0113 10.72717 0.0666 10.78542 0.0112 11.62056 0.0156 1

208T 0.27735 0.0679 0.360.51072 0.216 0.360.58314 0.858 0.360.76313 0.0164 0.360.86037 0.12 0.362.6145 0.998 0.36

*

�����������������������

����

4.6 60Co(1173.2keV)

60Co(1173keV) 60Co( ) 60Co( )

2m 7.76E-03 2.73E+01 5.43E+01 1.993m 4.92E-03 6.44E+01 1.30E+02 2.024m 3.26E-03 1.40E+02 2.85E+02 2.045m 2.28E-03 2.74E+02 5.67E+02 2.076m 1.66E-03 4.98E+02 1.04E+03 2.097m 1.25E-03 8.57E+02 1.80E+03 2.112m 1.55E-02 7.41E+00 1.44E+01 1.943m 9.85E-03 1.75E+01 3.44E+01 1.974m 6.53E-03 3.79E+01 7.57E+01 2.005m 4.56E-03 7.43E+01 1.50E+02 2.026m 3.32E-03 1.35E+02 2.75E+02 2.047m 2.49E-03 2.32E+02 4.78E+02 2.062m 2.33E-02 3.45E+00 6.63E+00 1.923m 1.48E-02 8.13E+00 1.58E+01 1.954m 9.79E-03 1.76E+01 3.48E+01 1.975m 6.84E-03 3.46E+01 6.91E+01 2.006m 4.99E-03 6.29E+01 1.27E+02 2.027m 3.74E-03 1.08E+02 2.20E+02 2.032m 3.10E-02 2.01E+00 3.82E+00 1.903m 1.97E-02 4.73E+00 9.12E+00 1.934m 1.31E-02 1.03E+01 2.01E+01 1.955m 9.12E-03 2.01E+01 3.98E+01 1.986m 6.65E-03 3.66E+01 7.30E+01 2.007m 4.98E-03 6.29E+01 1.27E+02 2.022m 3.88E-02 1.32E+00 2.49E+00 1.893m 2.46E-02 3.11E+00 5.95E+00 1.924m 1.63E-02 6.74E+00 1.31E+01 1.945m 1.14E-02 1.32E+01 2.60E+01 1.966m 8.31E-03 2.40E+01 4.76E+01 1.987m 6.23E-03 4.13E+01 8.27E+01 2.002m 4.65E-02 9.36E-01 1.76E+00 1.883m 2.95E-02 2.20E+00 4.20E+00 1.904m 1.96E-02 4.78E+00 9.23E+00 1.935m 1.37E-02 9.39E+00 1.83E+01 1.956m 9.97E-03 1.70E+01 3.36E+01 1.977m 7.48E-03 2.93E+01 5.83E+01 1.992m 5.43E-02 7.00E-01 1.31E+00 1.873m 3.45E-02 1.65E+00 3.12E+00 1.904m 2.28E-02 3.58E+00 6.87E+00 1.925m 1.60E-02 7.02E+00 1.36E+01 1.946m 1.16E-02 1.27E+01 2.50E+01 1.967m 8.72E-03 2.19E+01 4.34E+01 1.982m 6.21E-02 5.44E-01 1.01E+00 1.863m 3.94E-02 1.28E+00 2.42E+00 1.894m 2.61E-02 2.78E+00 5.32E+00 1.915m 1.82E-02 5.46E+00 1.06E+01 1.936m 1.33E-02 9.91E+00 1.94E+01 1.957m 9.97E-03 1.71E+01 3.36E+01 1.972m 6.98E-02 4.36E-01 8.08E-01 1.853m 4.43E-02 1.03E+00 1.93E+00 1.884m 2.94E-02 2.23E+00 4.24E+00 1.905m 2.05E-02 4.37E+00 8.43E+00 1.936m 1.50E-02 7.94E+00 1.55E+01 1.957m 1.12E-02 1.37E+01 2.68E+01 1.962m 7.76E-02 3.57E-01 6.60E-01 1.853m 4.92E-02 8.42E-01 1.58E+00 1.874m 3.26E-02 1.83E+00 3.47E+00 1.905m 2.28E-02 3.59E+00 6.89E+00 1.926m 1.66E-02 6.51E+00 1.26E+01 1.947m 1.25E-02 1.12E+01 2.19E+01 1.96

0.1

0.04

0.05

0.06

0.07

0.08

0.09

(Bq/g)

0.01

0.02

0.03

�����������������������

����

(a) 1 (b) 2 )

2.1

2.2

Ge

GeGe

�����������������������

����

2.3

2.4

6600CCoo

030

60

120

180150

901m

Ge

�����������������������

����

2.5

�����������������������

����

100kg =

OK

1000kg or

OK

D/C <1

D/C <1

Yes

Yes

Yes

No

No

No

Ge

3.1

�����������������������

����

4.1

y = 1.995 x -0.509

y = 2.514 x -0.498

00.010.020.030.040.050.060.070.080.090.1

0.110.120.130.140.150.160.17

0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 11000 12000 13000 14000

(cps

)

1173keV

1332.5keV

4.2 60Co

(a) 1 (b) ( )

�����������������������

����

�����������������

���

�����������������

0.1

1.0

10.0

100.0

1000.0

10000.0

h

0.01Bq/g0.02Bq/g0.03Bq/g0.04Bq/g0.05Bq/g0.06Bq/g0.07Bq/g0.08Bq/g0.09Bq/g0.10Bq/g

4.3 60Co(1173.2keV)

10

0.0

10.0

20.0

30.0

40.0

50.0

60.0

m2 /h

0.01Bq/g0.02Bq/g0.03Bq/g0.04Bq/g0.05Bq/g0.06Bq/g0.07Bq/g0.08Bq/g0.09Bq/g0.10Bq/g

4.4 60Co(1173.2keV)

10

�����������������������

����

�����������������

���

�����������������

60Co 1173keV)

y = 3.477x -0.531

y = 2.514x -0.498

0.001

0.01

0.1

1

0 2000 4000 6000 8000 10000 12000 14000 16000 18000 20000

(cps

)

60Co(1173.2keV)

4.5 EGS ( )

60Co 1332.5keV)

y = 1.995x -0.509

y = 2.602x -0.548

0.001

0.01

0.1

1

0 2000 4000 6000 8000 10000 12000 14000 16000 18000 20000

(cps

)

60Co(1332.5keV)

4.6 EGS ( )

�����������������������

����

60Co 1173keV)

y = 4.491x -0.522

y = 3.477 x -0.531

0.001

0.01

0.1

1

0 2000 4000 6000 8000 10000 12000 14000 16000 18000 20000

(cps

)

60Co(1173.2keV)

4.7 EGS

�����������������������

����

4.8 Ge

�����������������������

����

2.1 45

2.2

�����������������������

����

4.1 1

4.2 2

�����������������

���

�����������������

この印刷物は再生紙を使用しています