Albedo Dosimeters for Environmental Neutron Monitoring
Results of External Radiation Monitoring Dosimeters
Direct Environmental Penetrating Radiation
Quarterly Dose Summaries:
First Quarter - 2002 January 15, 2002 - April 2, 2002
Dosimeter Number
TLD Reading E7(1)
TLD Reading E8(1)
Neutron Dose (mrem)(2) Dosimeter in Field Continuously
Neutron Dose (mrem)(2) Dosimeter in Field Only When Road Open
Comment
1,1
38.91
69.63
3.9
1,2
38.61
70.12
4.0
2,1
47.16
78.71
4.0
2,2
45.98
79.87
4.4
3,1
45.19
139.38
13.1
3,2
45.32
150.09
14.6
4,1
37.40
48.78
1.1
4,2
37.43
50.07
1.3
5,1
36.14
47.45
1.1
5,2
37.95
51.17
1.4
6,1
43.53
70.29
3.3
6,2
42.35
72.96
3.9
7,1
40.53
87.01
6.2
7,2
40.87
86.66
6.1
8,1
38.62
49.65
1.1
9,1
34.76
44.32
0.9
Footnotes
(1)137Cs equivalent response, i.e., adjusted for reader correction and individual chip correction factors. (2) For DOELAP pure neutron irradiation catagories, the reported LANL 8823 detection limit is approximately 2 mrem.
First Quarter - 2001 January 12, 2001 - April 11, 2001
Dosimeter Number
TLD Reading E7(1)
TLD Reading E8(1)
Neutron Dose (mrem)(2) Dosimeter in Field Continuously
Neutron Dose (mrem)(2) Dosimeter in Field Only When Road Open
Comment
1,1
38.70
65.47
2.9
1,2
38.29
72.20
3.7
2,1
39.06
44.75
-0.2
2,2
39.05
46.29
0.0
3,1
44.29
157.54
15.2
3,2
44.30
141.10
13.0
4,1
37.24
44.88
0.1
4,2
36.15
46.96
0.4
5,1
38.12
42.91
-0.3
5,2
38.97
47.83
0.1
6,1
45.14
71.17
2.6
6,2
45.83
69.88
2.5
7,1
40.70
79.96
4.7
7,2
40.66
81.16
4.9
8,1
34.52
40.02
-0.5
9,1
35.83
43.1
0.1
10,1
12.9
11,1
107.5
12,1
121.7
Footnotes
(1)137Cs equivalent response, i.e., adjusted for reader correction and individual chip correction factors. (2) For DOELAP pure neutron irradiation catagories, the reported LANL 8823 detection limit is approximately 2 mrem.
Second Quarter - 2001 April 11, 2001 - June 20, 2001
Dosimeter Number
TLD Reading E7(1)
TLD Reading E8(1)
Neutron Dose (mrem)(2) Dosimeter in Field Continuously
Neutron Dose (mrem)(2) Dosimeter in Field Only When Road Open
Comment
1,1
28.16
47.68
2.0
1,2
28.65
46.43
1.8
2,1
30.54
37.17
0.2
2,2
31.71
38.30
0.2
3,1
35.08
98.82
8.5
3,2
32.30
89.57
7.5
4,1
28.94
36.03
0.2
4,2
32.53
40.27
0.3
5,1
28.83
37.43
0.5
5,2
28.91
36.63
0.3
6,1
31.46
45.20
1.2
6,2
30.68
42.13
0.9
7,1
34.51
63.02
3.3
7,2
30.72
58.22
3.2
8,1
28.12
35.08
0.3
9,1
27.16
34.27
0.2
10,1
13.0
11,1
77.1
12,1
131.3
Footnotes
(1)137Cs equivalent response, i.e., adjusted for reader correction and individual chip correction factors. (2) For DOELAP pure neutron irradiation catagories, the reported LANL 8823 detection limit is approximately 2 mrem.
Third Quarter - 2001 June 20, 2001 - October 15, 2001
Dosimeter Number
TLD Reading E7(1)
TLD Reading E8(1)
Neutron Dose (mrem)(2) Dosimeter in Field Continuously
Neutron Dose (mrem)(2) Dosimeter in Field Only When Road Open
Comment
1,1
50.88
113.60
8.0
1,2
48.26
109.38
7.8
2,1
52.79
64.69
0.7
2,2
51.18
64.65
0.9
3,1
60.87
301.29
33.8
3,2
64.16
295.28
32.4
4,1
46.97
57.66
0.5
4,2
43.83
55.89
0.7
5,1
45.16
57.19
0.7
5,2
45.08
54.31
0.3
6,1
50.49
106.49
7.1
6,2
51.13
99.60
6.0
7,1
52.46
151.46
13.3
7,2
46.27
59.03
0.8
Invalid result due to damaged phosphor
8,1
44.77
56.16
0.6
9,1
38.68
51.10
0.7
10,1
26.7
11,1
163.2
12,1
171.6
Footnotes
(1)137Cs equivalent response, i.e., adjusted for reader correction and individual chip correction factors. (2) For DOELAP pure neutron irradiation catagories, the reported LANL 8823 detection limit is approximately 2 mrem.
Fourth Quarter - 2001 October 15, 2001 - January 15, 2002
Dosimeter Number
TLD Reading E7(1)
TLD Reading E8(1)
Neutron Dose (mrem)(2) Dosimeter in Field Continuously
Neutron Dose (mrem)(2) Dosimeter in Field Only When Road Open
Comment
1,1
40.8
68.86
3.6
1,2
42.48
66.06
2.9
2,1
47.32
114.94
9.3
2,2
48.48
116.8
9.4
3,1
46.66
124.86
10.8
3,2
49.62
125.51
10.4
4,1
39.03
51.34
1.3
4,2
42.15
53.44
1.1
5,1
39.43
47.8
0.7
5,2
41.48
51.7
1.0
6,1
49.2
75.58
3.3
6,2
48.66
73.18
3.1
7,1
42.16
78.66
4.8
7,2
57.95
99.92
5.6
8,1
47.77
58.27
1.0
9,1
37.89
48.87
1.1
10,1
5.1
11,1
32.2
12,1
14.8
Footnotes
(1)137Cs equivalent response, i.e., adjusted for reader correction and individual chip correction factors. (2) For DOELAP pure neutron irradiation catagories, the reported LANL 8823 detection limit is approximately 2 mrem.
First Quarter - 2000 January 19, 2000 - April 12, 2000
Badge ID
TLD Reading E7
TLD Reading E8
Neutron Dose (mrem) Dosimeter in Field Continuously(1)
1,1
46.32
61.04
0.5
1,2
47.13
63.24
0.7
2,1
50.19
79.25
2.6
2,2
51.34
70.35
1.2
3,1
47.41
65.57
1.0
3,2
46.13
64.37
1.0
4,1
45.65
67.99
1.7
4,2
49.96
77.90
2.5
5,1
44.78
58.99
0.5
5,2
42.01
60.51
1.1
6,1
48.94
67.78
1.1
6,2
49.90
73.76
1.9
7,1
45.90
57.29
0.1
7,2
49.41
64.25
0.6
8,1
45.22
54.74
-0.2
8,2
39.42
56.15
0.8
9,1
26.80
35.42
-0.1
Footnotes
(1) Pajarito Road was not closed for radiation protection purposes during this monitoring period.
Second Quarter - 2000 April 12, 2000 - July 17, 2000
Badge ID
TLD Reading(1) E7
TLD Reading(1) E8
Neutron Dose (mrem)(2) Dosimeter in Field Continuously
1,1
32.26
39.77
0.4
1,2
34.15
41.13
0.3
2,1
39.32
50.09
0.8
2,2
35.80
47.03
0.9
3,1
34.17
46.54
1.1
3,2
33.68
46.85
1.2
4,1
36.08
48.27
1.0
4,2
37.54
52.19
1.4
5,1
35.38
46.35
0.8
5,2
34.85
44.70
0.7
6,1
37.93
51.77
1.3
6,2
43.94
55.03
0.9
7,1
37.92
46.30
0.5
7,2
35.43
46.31
0.8
8,1
32.57
41.58
0.6
8,2
28.04
38.60
0.8
9,1
16.31
19.26
-0.5
Pajarito Road was not closed for radiation protection purposes during this monitoring period.
Footnotes
(1) Adjusted light readings, with fading correction, TLD reader correction factor and individual chip correction. (2) Initial studies give a detection limit for neutron dose of approximately 2 mrem.
Third Quarter - 2000 July 17, 2000 - October 18, 2000
Badge ID
TLD Reading(1) E7
TLD Reading(1) E8
Neutron Dose (mrem)(2) Dosimeter in Field Continuously
Neutron Dose (mrem)(2) Dosimeter in Field Only When Road Open
1,1
40.16
83.36
4.9
1,2
34.19
62.09
2.3
2,2
41.76
59.48
1.2
2,1
38.48
54.05
0.5
3,2
45.07
164.72
16.0
3,1
38.01
137.87
12.7
4,1
41.77
69.63
1.9
4,2
36.68
57.76
1.3
5,1
38.98
49.28
0.1
5,2
32.00
41.17
-0.5
6,2
49.25
80.38
3.1
6,1
38.03
63.63
2.8
7,1
42.97
104.90
7.6
7,2
35.14
82.77
5.1
8,1
33.47
46.79
0.3
8,2
32.91
44.42
0.3
9,1
18.73
26.31
-0.1
Footnotes
(1) Adjusted light readings, with fading correction, TLD reader correction factor and individual chip correction. (2) Initial studies give a detection limit for neutron dose of approximately 2 mrem.
Fourth Quarter - 2000 October 18, 2000 - January 12, 2001
Badge ID
TLD Reading(1) E7
TLD Reading(1) E8
Neutron Dose (mrem)(2) Dosimeter in Field Continuously
Neutron Dose (mrem)(2) Dosimeter in Field Only When Road Open
1,1
35.77
58.01
2.1
1,2
34.63
46.42
0.6
2,1
39.69
63.74
2.3
2,2
38.88
58.53
1.7
3,1
38.12
77.10
4.5
3,2
39.31
109.90
9.1
4,1
35.06
44.56
0.2
4,2
32.91
41.08
0.0
5,1
33.71
41.49
0.0
5,2
34.02
42.08
0.0
6,1
45.00
54.23
0.2
6,2
41.68
57.70
1.2
7,1
38.59
75.62
4.2
7,2
38.19
59.49
1.9
8,1
40.66
49.62
0.4
8,2
33.17
40.63
0.0
9,1
17.65
23.80
0.0
Footnotes
(1)137Cs equivalent response, i.e., adjusted for reader correction and individual chip correction factors. (2) For DOELAP pure neutron irradiation catagories, the reported LANL 8823 detection limit is approximately 2 mrem.
First Quarter - 1999 January 29, 1999 - April 19, 1999
Dosimeter #
TLD Reading E7(1)
TLD Reading E8(1)
Neutron Dose (mrem)(2) Dosimeter in Field Continuously
Neutron Dose (mrem)(2) Dosimeter in Field Only When Road Open
Comment
1,1
35.05
58.71
2.3
Pajarito Road was not closed for radiation protection purposes during this monitoring period.
1,2
34.31
64.01
3.1
2,1
40.09
51.58
0.6
2,2
38.88
54.50
1.2
3,1
38.97
142.00
13.9
3,2
39.16
124.96
11.4
4,1
34.72
50.59
1.2
4,2
35.22
51.28
1.2
5,1
35.85
53.25
1.5
5,2
34.51
41.06
-0.2
6,1
45.94
59.70
1.0
6,2
44.65
72.71
2.9
7,1
37.05
80.09
5.2
7,2
37.86
75.40
4.4
8,1
33.26
44.55
0.6
9,1
31.06
40.96
0.6
Footnotes
(1)137Cs equivalent response, i.e., adjusted for reader correction and individual chip correction factors. (2) For DOELAP pure neutron irradiation catagories, the reported LANL 8823 detection limit is approximately 2 mrem.
Second Quarter - 1999 April 19, 1999 - July 15, 1999
Dosimeter #
TLD Reading E7(1)
TLD Reading E8(1)
Neutron Dose (mrem)(2) Dosimeter in Field Continuously
Neutron Dose (mrem)(2) Dosimeter in Field Only When Road Open
Comment
1,1
35.96
47.35
0.8
Pajarito Road was not closed for radiation protection purposes during this monitoring period.
1,2
34.62
48.96
1.2
2,1
37.26
63.60
3.1
2,2
40.56
66.95
3.1
3,1
35.68
54.61
1.9
3,2
34.83
57.56
2.4
4,1
35.67
54.59
1.8
4,2
32.69
43.46
0.8
5,1
32.01
44.59
1.0
5,2
33.85
43.32
0.5
6,1
47.15
64.63
1.7
6,2
36.66
51.15
1.3
7,1
31.85
48.02
1.5
7,2
32.29
47.54
1.3
8,1
32.55
41.81
0.5
9,1
27.11
34.33
0.1
Footnotes
(1)137Cs equivalent response, i.e., adjusted for reader correction and individual chip correction factors. (2) For DOELAP pure neutron irradiation catagories, the reported LANL 8823 detection limit is approximately 2 mrem.
Third Quarter - 1999 July 15, 1999 - October 19, 1999
Dosimeter #
TLD Reading E7(1)
TLD Reading E8(1)
Neutron Dose (mrem)(2) Dosimeter in Field Continuously
Neutron Dose (mrem)(2) Dosimeter in Field Only When Road Open
Comment
1,1
38.49
76.35
4.6
Pajarito Road was not closed for radiation protection purposes during this monitoring period.
1,2
38.86
74.65
4.4
2,1
6.03
68.31
8.3
Dosimeter was water-damaged, and TLD E7 had a very incomplete glow curve, accounting for the low E7 reading.
2,2
43.68
63.61
2.1
3,1
49.89
164.43
15.7
Dosimeter had a white residue.
3,2
45.20
139.54
12.8
4,1
37.76
63.89
2.9
4,2
36.40
56.84
2.1
5,1
39.37
49.00
0.6
5,2
35.16
47.71
1.0
6,1
38.86
72.86
4.1
6,2
40.19
70.79
3.5
7,1
38.16
95.23
7.5
7,2
38.48
93.84
7.3
8,1
35.25
47.73
1.0
9,1
31.11
42.77
0.8
Footnotes
(1)137Cs equivalent response, i.e., adjusted for reader correction and individual chip correction factors. (2) For DOELAP pure neutron irradiation catagories, the reported LANL 8823 detection limit is approximately 2 mrem.
Fourth Quarter - 1999 October 19, 1999 - January 19, 2000
Dosimeter #
TLD Reading E7(1)
TLD Reading E8(1)
Neutron Dose (mrem)(2) Dosimeter in Field Continuously
Neutron Dose (mrem)(2) Dosimeter in Field Only When Road Open
Comment
1,1
39.24
55.93
2.5
Pajarito Road was not closed for radiation protection purposes during this monitoring period.
1,2
38.80
54.28
2.3
2,1
40.79
70.11
4.4
2,2
44.05
72.14
4.1
3,1
43.70
77.92
5.0
3,2
43.87
75.89
4.6
4,1
36.42
53.53
2.5
4,2
39.92
57.09
2.5
5,1
36.79
48.98
1.9
5,2
33.64
47.39
2.1
6,1
44.58
65.43
3.1
6,2
43.25
65.36
3.1
7,1
38.51
59.06
2.9
7,2
37.43
59.57
3.1
8,1
33.89
47.15
1.9
9,1
32.70
49.08
2.3
Footnotes
(1)137Cs equivalent response, i.e., adjusted for reader correction and individual chip correction factors. (2) For DOELAP pure neutron irradiation catagories, the reported LANL 8823 detection limit is approximately 2 mrem.
First Quarter - 1998 January 16, 1998 - April 20, 1998
Dosimeter #
TLD Reading E7(1)
TLD Reading E8(1)
Neutron Dose (mrem)(2) Dosimeter in Field Continuously
Neutron Dose (mrem)(2) Dosimeter in Field Only When Road Open
Comment
1,1
36.13
49.89
1.5
Pajarito Road was not closed for radiation protection purposes during this monitoring period.
1,2
36.37
54.05
1.9
2,1
40.00
60.59
2.3
2,2
38.51
63.19
2.9
3,1
35.47
73.39
5.0
3,2
34.57
80.08
6.0
4,1
31.69
43.51
1.0
4,2
32.60
39.70
0.4
5,1
32.67
40.29
0.4
5,2
31.62
42.67
1.0
6,1
37.62
51.33
1.5
6,2
38.81
50.55
1.0
7,1
32.86
52.26
2.3
7,2
32.18
54.41
2.7
8,1
32.11
40.10
0.6
9,1
30.55
40.78
0.8
Footnotes
(1)137Cs equivalent response, i.e., adjusted for reader correction and individual chip correction factors. (2) For DOELAP pure neutron irradiation catagories, the reported LANL 8823 detection limit is approximately 2 mrem.
Second Quarter - 1998 April 20, 1998 - July 16, 1998
Dosimeter #
TLD Reading E7(1)
TLD Reading E8(1)
Neutron Dose (mrem)(2) Dosimeter in Field Continuously
Neutron Dose (mrem)(2) Dosimeter in Field Only When Road Open
Comment
1,1
37.95
51.07
0.8
1,2
38.27
47.87
0.4
2,1
41.24
78.23
4.4
2,2
42.32
72.84
3.3
3,1
38.87
57.20
1.7
3,2
37.71
48.45
0.6
4,1
39.96
73.86
3.9
4,2
38.33
60.09
2.1
5,1
37.05
48.10
0.6
5,2
37.58
47.96
0.4
6,1
41.35
59.55
1.7
6,2
42.67
63.30
2.1
7,1
40.32
54.98
1.0
7,2
36.86
46.11
0.4
8,1
38.57
49.81
0.1
9,1
Dosimeter lost.
Footnotes
(1)137Cs equivalent response, i.e., adjusted for reader correction and individual chip correction factors. (2) For DOELAP pure neutron irradiation catagories, the reported LANL 8823 detection limit is approximately 2 mrem.
Third Quarter - 1998 July 16, 1998 - October 15, 1998
Dosimeter #
TLD Reading E7(1)
TLD Reading E8(1)
Neutron Dose (mrem)(2) Dosimeter in Field Continuously
Neutron Dose (mrem)(2) Dosimeter in Field Only When Road Open
Comment
1,1
32.33
50.58
2.1
Pajarito Road was not closed for radiation protection purposes during this monitoring period.
1,2
36.27
53.51
1.9
2,1
33.12
47.04
1.5
2,2
35.00
55.01
2.3
3,1
32.76
63.25
3.7
3,2
31.23
60.40
3.5
4,1
32.63
80.53
6.2
4,2
33.82
47.11
1.2
5,1
38.91
59.01
2.3
5,2
40.36
65.29
3.1
6,1
40.66
65.71
3.1
6,2
30.11
41.15
1.0
7,1
37.16
46.61
0.8
7,2
30.48
39.73
0.6
8,1
36.35
90.59
7.3
9,1
Dosimeter lost.
Footnotes
(1)137Cs equivalent response, i.e., adjusted for reader correction and individual chip correction factors. (2) For DOELAP pure neutron irradiation catagories, the reported LANL 8823 detection limit is approximately 2 mrem.
Fourth Quarter - 1998 October 15, 1998 - January 29, 1999
Dosimeter #
TLD Reading E7(1)
TLD Reading E8(1)
Neutron Dose (mrem)(2) Dosimeter in Field Continuously
Neutron Dose (mrem)(2) Dosimeter in Field Only When Road Open
Comment
1,1
41.75
45.89
-0.2
Pajarito Road was not closed for radiation protection purposes during this monitoring period.
1,2
41.02
55.04
1.2
2,1
46.01
101.48
7.3
2,2
45.01
95.07
6.4
3,1
43.87
56.04
1.0
3,2
41.53
49.33
0.4
4,1
40.63
48.59
0.2
4,2
40.00
49.91
0.6
5,1
38.39
43.39
0.0
5,2
39.77
43.73
-0.2
6,1
46.68
54.06
0.2
6,2
46.75
60.09
1.0
7,1
43.47
50.95
0.2
7,2
43.37
49.10
0.2
8,1
38.28
44.85
0.0
9,1
37.85
42.83
0.0
Footnotes
(1)137Cs equivalent response, i.e., adjusted for reader correction and individual chip correction factors. (2) For DOELAP pure neutron irradiation catagories, the reported LANL 8823 detection limit is approximately 2 mrem.
Second Quarter - 1997 May 16, 1997 - July 12, 1997
Dosimeter #
TLD Reading E7(1)
TLD Reading E8(1)
Neutron Dose (mrem)(2) Dosimeter in Field Continuously
Neutron Dose (mrem)(2) Dosimeter in Field Only When Road Open
Comment
1,1
18.53
32.85
2.1
Pajarito Road was not closed for radiation protection purposes during this monitoring period.
1,2
19.49
32.41
1.9
2,1
19.67
52.51
4.8
2,2
21.25
48.27
3.9
3,1
19.04
60.69
6.0
3,2
20.97
60.49
5.8
4,1
17.45
22.05
0.6
4,2
18.16
23.19
0.8
5,1
17.97
22.38
0.6
5,2
17.94
23.01
0.8
6,1
18.96
30.52
1.7
6,2
20.64
33.12
1.9
7,1
18.00
36.77
2.7
7,2
17.77
38.27
2.9
8,1
15.54
20.27
0.6
9,1
Dosimeter lost.
Footnotes
(1)137Cs equivalent response, i.e., adjusted for reader correction and individual chip correction factors. (2) For DOELAP pure neutron irradiation catagories, the reported LANL 8823 detection limit is approximately 2 mrem.
Third Quarter - 1997 July 12, 1997 - October 3, 1997
Dosimeter #
TLD Reading E7(1)
TLD Reading E8(1)
Neutron Dose (mrem)(2) Dosimeter in Field Continuously
Neutron Dose (mrem)(2) Dosimeter in Field Only When Road Open
Comment
1,1
27.30
61.50
4.4
Pajarito Road was not closed for radiation protection purposes during this monitoring period.
1,2
28.90
65.21
4.8
2,1
31.24
58.05
3.3
2,2
31.09
63.43
4.1
3,1
33.33
150.43
16.4
3,2
31.90
153.47
17.0
4,1
27.48
70.07
5.6
4,2
28.51
68.68
5.2
5,1
24.73
33.80
0.8
5,2
24.33
32.41
0.6
6,1
32.29
77.65
6.0
6,2
33.03
76.50
5.8
7,1
27.93
79.70
7.0
7,2
28.84
84.01
7.5
8,1
25.20
33.85
0.6
9,1
25.23
31.31
0.4
Footnotes
(1)137Cs equivalent response, i.e., adjusted for reader correction and individual chip correction factors. (2) For DOELAP pure neutron irradiation catagories, the reported LANL 8823 detection limit is approximately 2 mrem.
Fourth Quarter - 1997 October 3, 1997 - January 16, 1998
Dosimeter #
TLD Reading E7(1)
TLD Reading E8(1)
Neutron Dose (mrem)(2) Dosimeter in Field Continuously
Neutron Dose (mrem)(2) Dosimeter in Field Only When Road Open
Comment
1,1
36.91
208.15
24.2
1,2
30.80
58.08
3.3
2,1
38.41
60.25
2.7
2,2
41.28
53.04
1.2
3,1
59.67
623.76
81.2
3,2
38.28
138.47
13.9
4,1
27.00
44.16
1.9
4,2
27.36
41.49
1.5
5,1
29.86
39.64
0.8
5,2
25.88
40.21
1.5
6,1
41.95
246.93
29.2
6,2
43.59
57.23
1.5
7,1
42.14
316.96
39.4
7,2
34.56
72.34
5.0
8,1
40.38
41.04
-0.4
9,1
Dosimeter lost.
Footnotes
(1)137Cs equivalent response, i.e., adjusted for reader correction and individual chip correction factors. (2) For DOELAP pure neutron irradiation catagories, the reported LANL 8823 detection limit is approximately 2 mrem.
History
The Consent Decree between the Department of Energy (DOE) and the Concerned Citizen's for Nuclear Safety (CCNS) required that seven albedo TLDs be placed on the north, south, and east sides of TA-18. The albedo TLDs were operated for a period of five years, from 1997-Q2 through 2002-Q1.
The albedo dosimeters are sited at the following locations:
Location/Description
Dosimeter #
Dosimeter #
NEWNET Kappa site
1,1
1,2
Entrance to TA-36
2,1
2,2
Personnel gate at TA-18 parking lot
3,1
3,2
P2 booster station at TA-54 entrance
4,1
4,2
Entrance to TA-51
5,1
5,2
Half way up Pajarito hill west of TA-18 entrance
6,1
6,2
Pajarito road entrance to TA-18
7,1
7,2
TA-49 (background)
8,1
Santa Fe (background)
9,1
TA-3-130 North fence
10,1
TA-3-130 inner east fence
11,1
TA-3-130 inner south fence
12,1
The LANL 8823 personnel dosimeters that are used are accredited for personnel dosimetry for all the radiation categories described here under the Department of Energy Laboratory Accreditation Program (DOELAP). Sixteen albedo TLD dosimeters were emplaced to determine neutron radiation levels. The dosimeters are designed to measure external radiation when worn by workers or other individuals that may receive a radiation dose, and so they are calibrated to include backscatter from the body. This was taken into account for environmental monitoring by placing these dosimeters on 20 cm x 20 cm x 15 cm Lucite phantoms.
Two dosimeters are located at stations 1-7. On a normal, routine basis, these locations have no restrictions in terms of public access. However, some operations at TA-18 can produce a dose of more than 1 mrem at Pajarito Road or at the TA-36 road to Kappa Site. A few times a year, when large operations are conducted, these roads are closed to public access. During road closures, one dosimeter at each station is taken out of the field and placed in a vault. Thus, we have one measurement that represents the full calendar quarter and one measurement that represents the time period during the calendar quarter when a member of the public could be present.
Each dosimeter contains eight TLD chips, and are made of different materials according to what they are intended to measure. TLD E8 is LiF and is enriched in the isotope Li-6 that makes it more sensitive to thermal neutrons. TLD E7 is also LiF, but depleted in Li-6 making it relatively insensitive to thermal neutrons.
The dosimeter holder has different filters over the various TLDs to alter their responses to different types and energies of radiation. The TLD pair E7 and E8 with the opening on the back of the cadmium box is the albedo dosimeter.
The dosimeter is designed to internally provide an estimate of the neutron correction factor (NCF), which is the ratio of the true neutron dose to the corrected albedo reading in dosimeter E8. This is used when individuals are exposed to a number of different neutron fields with different energy spectra in their work assignments. For monitoring at TA-18, however, the monitoring locations exhibit fairly similar thermalized spectra. For situations such as this, it is more accurate to measure the neutron correction factor directly. The measurements are discussed in the memorandum ENV-MAQ:00-322. As a result, a neutron correction factor of 0.145 is used in the TA-18 neutron dose calculation, as discussed below.
The tables present the light readings from each dosimeter, after being adjusted for fading (when required), the reader corrections, and individual chip correction factors.
The background radiation signal that the dosimeters would receive while they were not in the field has been subtracted in determining the neutron doses. The light readings for TLDs E7 and E8 were corrected using empirical formulas. For TLD E7, the added signal that this TLD would receive from background radiation is 1.84 + 0.16 * (number of days of exposure). The corresponding formula for TLD E8 is 2.872 + 0.265 * (number of days of exposure).
The procedure used to calculate the neutron dose is to determine the albedo response. TLDs E7 and E8 were first corrected for the radiation they received while not in the field, as described above. TLD E8, which is sensitive to thermal neutron radiation and photon radiation, was corrected for background photon radiation by subtracting E7 (which is only sensitive to photon radiation) from E8, to form the net (neutron) signal in E8, called E8N. The value E8N was then multiplied by the neutron correction factor to obtain the neutron dose.
Environment 