sign in sign up
<<
Home , Asahikawa, Ashibetsu, Bibai, Iwamizawa, Kushiro (town), Nayoro

External Dose Data

External Exposure due to Natural Radiation

[National Institute of Radiological Sciences) surveymeter were used for measurement of given A field survey of exposure rates due to natural stations and their readings are compared for drawing a radiation has been conducted throughout the Hokkai­ relationship between them. do district of during June 1971. Practically the direct reading of the thsurveymeter The situation of the district in Japan is were reduced into the reading of the plastic chamber shown in Figure 1. Distribution of observed locations corresponding to it from the relationship of linear in the district is indicated in Figure 2. In each location, proportion. Systematic error at culiblation (60Co) and from one to five sites containing at least 5 stations uading error (random) of the pfastic chamber were were made there. A total of 81 sites were measured. respectively within ±6 % (maximum over all error) and Observations were made using a spherical ioniza­ within ±3.5 % (standard error for 6jLtR/hr). Reading error tion chamber and several scientillation surveymeters. error of the survey-meter is about ±3%. (standard error The spherical plastic ionization chamber of which inner for 6juR/hr) diameter and wall thickness are respectively 200 mm Measurements in open bare field were made at one and 3 mm (acrylate) has adequate sensitivity for field meter above the ground and outdoor gamma-rays survey. The chamber was used as a standard of exposure rates (juR/hr) were due to cosmic rays as well apparatus, but it is difficult to observe all locations as terrestrial radiation, so that it may be considered only by the apparatus, so that a surveymeter with a that the contribution of fallout due to artificial origin Nal (Tl) Y'

x 2" l\lal(T1) scintillator and the other with tion in each location are shown in Table 1, and a 3"

Table 1. Gamma-ray Exposure Rates due to Natural Radiation in each Location of the Hokkaido district - June 1971 by S. Abe, K. Arai, Y. Inoue and K. Fujimoto (National Institute of Radiological Sciences)

Exposure Rate Number of Sites Sub- Apparatus* Prefecture Location (MR/hr) measured in each Location

Soya 1 Soya-misaki 6.9 C 2 8.6 C 3 Hamatombetsu 6.6 C 4 Esashi 9.3 C Rumoi 5 Teshio 9.0 A, C 1 6 Rumoi 7.9 C 1 I shikari 7 Hamamasu 7.8 C 2 8 7.9 C 5 9 Shikotsu-ko 6.3 A, C 1 10 Chitose 6.3 C 1

(1) Sub- Exposure Rate Apparatus* Number of Sites Prefecture Location (nR/hr) measured in each Location

Sorachi 11 Takikawa 9.5 C 1 12 9.2 C 1 13 9.5 C 1 14 Asbibetsu 8.6 C 1 Shiribeshi 15 7.3 C 3 16 Kyowa, Tomari 9.3 C 6 17 Shimamaki 8.4 C 1 18 Kutchan 7.6 C Hiyama 19 Kitahiyama 9.5 c 20 Esashi 8.0 c Oshima 21 Matsumae 9.8 A, C 22 Kikonai 8.3 C 23 7.8 C 24 Mori 5.3 C 25 Yakumo 7.1 C 26 Oshamambe 8.2 C Iburi 27 Abuta 5.4 c 28 7.0 A, C 29 6.1 C 30 9.3 C 31 Mukawa 6.0 c Hidaka 32 Shizunai 8.0 c 33 Urakawa 9.2 c i l 34 Erimo 8.6 c Tokachi 35 Kamishihoro 7.9 c 36 Shintoku 9.2 c 37 8.4 A, C '•;. 38 Sarabetsu 6.6 C 39 Hiroo 8.2 C 40 Ashoro 8.1 C 41 Akan 5.9 A, C 42 Onbetsu 6.6 C 43 Kushiro 7.5 A, C 44 Akkeshi 8.9 C 45 Teshikaga 5.5 C Nemuro 46 Shibetsu 5.0 C 47 Nemuro 7.2 C 48 Okoppe 9.0 C 49 Mombetsu 8.1 A, C 50 Rubeshibe 9.3 C 51 6.9 C 52 Abashiri 7.1 A, C Kam&awa 53 Otoineppu 8.0 A, C 54 8.9 C 55 10.8 A, C 3 56 Furano 9.2 A, C 57 Kamikawa 11.0 C * A: Spherical Ionization Chamber C: Surveymeite r with l"6 x 1" Nal (Tl) Scintillator

(2) Table 2 Population Exposure due to Natural Radiation in Each Sub-district of the Hokkaido District by S. Abe, K. Arai, Y. Inoue and K. Fujimoto (National Institute of Radiological Sciences)

Exposure Rate ± Standard Deviation Population* Number District itiR/hv) (X 1,000) of Sites East 7.4 ± 0.8 764 14 Central 9.4 ±1.2 1,860 29 South 7.7 ± 0.9 2,561 39 Hokkaido 8.3 ± 1.3 5,184 81 Fig. 1 1970 National Census

Figure 1 : The Situation of Hokkaido District in Japan

140" 145'E

(3) CA -^

0 3 V~x' o Figur e 2 Distribution of Observed Locations \ r^ \ 4 5 1 1. Soya-misaki 25. Yakumo \~ s 2. Wakkanai 26. Oshamambe \° •' 3 Hamatonbetsu 27. Abuta 1 I 28. Muroran 1 /1 s 4. Esashi \ V \ 48 5. Teshio 29. NoboribBtsu 1 (^ / 6. Rumci 30. Tomakomai I 7 ~_l / •s Hamamasu 31. Mukawa / 54 / 8. Sapporo 31 Shizunai % i ; o i b« 9. Shikotsu-ko 33. Urakawa /i \ 10. Chitobe 34. Erimo 1 J 1 / ( 1 35. Kamishiboro f r * / • 1. Takikawa •• 12. Bibai 36. Shintoku \ / /-/-i' 1 13. Iwamizawa 37. Obihiro # • Hi 52 / i 1 1 i 14. 38. SarabBtsu 6 1 1 ) o\ v_y 15. Otaru 39. Hiroo O f i <. .. 7/ IB. Kyowa, 1 oma n 40. Ashor 0 • i 1 17. Shimamaki 41. Akan / '-, 55 50 ^ 51 / * 18. Kuchian ) o K O ° f\ 19. Kitahiyanu / O -'~\ / / i 46 V, Esashi /u. 1 O V Matsumas 7*\ 11 / 4 21. \ O 22. Mkonai /o \\ 14 / 45\ Hakodate y 23. 35 47^ Mori / o \ 1 '^'9 ° I \ 24. 1 n 12 /'o 56 ; * \ "A 40 ,- * \ C / p> 15 \ % • ( 36 O J 1 13 \ 1 n --'" ••"• O'v / * 8 / / 1 / 4 1 1 1 t 1 ,—• ' o \ 43 1 \ t # 16 •% t .• 1 37 42^- 1 1 1 \ i° K O/ J^ N 17 ( 10 i / / / 9 O y i I o 1 1 / \ 38 ^J, * 1 S" \ ^1 • 1 / 30 N U 1\ -«• 26/ 27 29 0/ L 42 Onbetsu 51. Kitaml i—is i [ / \ 32 Kushiro V 28 > /39 43. 52. Abashiri 'o ^* i 44. Akkeshi 52, Otoineppu (25 \y o 45. Teshikaga 54. Nayoro / 0 s *? \ 33 ( 46. Shibetsu 55. Asahikawa 1 N. "A\ i N \ \24 D 47. Nemuro 56. Furano 1 t 48. Okoppe 57. Kamikawa ( r^ V 34 j 49. Monbetsu \ o/ 50. Rubeshibe 20 1 V 1 \ / 23 . / 22 J ^0 > / c

\21 \t ) / / J^A \