Radioactive Materials Unit
PO Box 64975
St. Paul, MN 55164-0975
Phone: 651-201-4400 • Fax 651-201-3999
PRAIRIE ISLAND NUCLEAR GENERATING PLANT
INDEPENDENT SPENT FUEL STORAGE INSTALLATION
Introduction
This report provides data on radiation levels inside the Xcel Energy, Inc. (XE) Independent Spent Fuel
Storage Installation (ISFSI) at the Prairie Island Nuclear Generating Plant (PINGP) for May 2014. The
data contained in this report were gathered in accordance with agreements between Xcel Energy, Inc.
and the Minnesota Department of Health (MDH).
At the end of May 2014, 35 casks were storing spent fuel inside the Independent Spent Fuel Storage
Installation. The last cask to be moved to the Independent Spent Fuel Storage Installation was placed on
June 25, 2013.
Pressurized Ionization Chamber (PIC) Monitoring
During this reporting period, daily radiation data were collected by the Pressurized Ionization Chamber
system, which was installed in January 1995. The system consists of two ion chambers, computer
memories and modems that are contacted every 15 minutes by the Minnesota Department of Health
computers in St. Paul. The computers automatically page Minnesota Department of Health staff if unusual
radiation levels are detected or if there are communication errors. Pressurized Ionization Chamber No. 1
is located about 100 feet north of the casks and Pressurized Ionization Chamber No. 2 is about 100 feet
south.
Data were collected from May 1, 2014 to May 31, 2014 and are summarized in Table 1 for Pressurized
Ionization Chamber No. 1 and Table 2 for Pressurized Ionization Chamber No. 2. Daily averages are
presented, though data for every 15 minutes are available. A chart showing the daily averages for each
Pressurized Ionization Chamber is also included. Pressurized Ionization Chamber No. 1 did not work in
May. Pressurized Ionization Chamber No. 2 was working properly during the month of May.
Analysis and Comments
Pressurized Ionization Chamber No. 2 readings ranged from 152.8 to 162.0 μR/hr. The normal range of
ambient radiation levels inside the Independent Spent Fuel Storage Installation near the casks (about 100
feet away) has been 150 to 190 μR/hr.
Before any casks were in place, the natural background radiation levels inside the Independent Spent
Fuel Storage Installation ranged from 5 to 15 μR/hr.
Additional monitoring data on radioactivity levels in other media (air, for example) are available in the
annual Minnesota Department of Health "Environmental Radiation Data Report."
For more information, go to: http://www.health.state.mn.us/divs/eh/radiation/monitor/index.html or contact
Brandon Juran at [email protected] or 651-201-4526.
1
Table 1: May 2014 Data Report for Pressurized Ionization Chamber No. 1
Start
Date
Start
Times
End
Times
Dose
(mR)
Intv
Status
2
400v
6v
Avg
(uR/h)
Max
(uR/h)
Min
(uR/h)
Cnt
Table 2: May 2014 Data Report for Pressurized Ionization Chamber No. 2
Start Date
Start
Times
5/1/2014
0:13
5/2/2014
0:13
5/3/2014
0:01
5/4/2014
0:01
5/5/2014
0:13
5/6/2014
0:11
5/7/2014
0:05
5/8/2014
0:09
5/9/2014
0:02
5/10/2014
0:11
5/11/2014
0:09
5/12/2014
0:11
5/13/2014
0:02
5/14/2014
0:11
5/15/2014
0:01
5/16/2014
0:10
5/17/2014
0:11
5/18/2014
0:10
5/19/2014
0:02
5/20/2014
0:13
5/21/2014
0:11
5/22/2014
0:10
5/23/2014
0:11
5/24/2014
0:11
5/25/2014
0:01
5/26/2014
0:11
5/27/2014
0:13
5/28/2014
0:01
5/29/2014
0:29
5/30/2014
0:14
5/31/2014
0:14
5/1/14 to 5/31/14
End
Times
23:59
23:46
23:46
23:59
23:59
23:50
23:56
23:47
23:56
23:56
23:56
23:47
23:56
23:46
23:54
23:56
23:56
23:47
23:58
23:54
23:56
23:54
23:54
23:46
23:56
23:59
23:46
23:26
23:59
23:59
23:56
Dose
(mR)
3.78
3.75
3.74
3.73
3.72
3.73
3.73
3.76
3.75
3.75
3.75
3.77
3.74
3.73
3.74
3.74
3.73
3.72
3.75
3.74
3.73
3.72
3.72
3.71
3.72
3.73
3.74
3.72
3.72
3.71
3.72
115.7
Intv
Status
900
900
900
900
900
900
900
900
900
900
900
900
900
900
900
900
900
900
900
900
900
900
900
900
900
900
900
900
900
900
900
900
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
3
300v
277
278
277
278
279
279
279
279
279
279
280
280
278
278
278
278
279
280
279
280
280
280
280
281
281
282
281
281
281
282
282
279
12v
14.2
14.2
14.2
14.2
14.2
14.2
14.2
14.2
14.2
14.2
14.2
14.2
14.2
14.2
14.2
14.2
14.2
14.2
14.2
14.2
14.2
14.2
14.2
14.2
14.2
14.2
14.2
14.2
14.2
14.2
14.2
14.2
Avg
(uR/h)
157.4
156.2
156.0
155.5
155.2
155.3
155.6
156.6
156.2
156.1
156.3
157.0
156.0
155.6
155.8
155.7
155.4
155.1
156.3
155.7
155.4
155.1
154.8
154.7
154.8
155.3
156.0
154.9
154.8
154.7
154.8
155.6
Max
(uR/h)
159.3
156.9
157.4
156.5
156.2
156.2
161.8
160.4
156.7
157.3
160.1
162.0
157.0
157.1
156.5
156.8
156.7
156.5
159.6
156.5
156.3
156.4
156.5
156.1
156.0
160.3
157.1
156.1
156.2
155.8
155.6
162.0
Min
(uR/h)
155.7
155.5
154.9
154.4
154.2
154.5
154.8
155.6
155.4
155.0
155.0
155.4
155.1
154.3
155.2
154.8
154.2
153.8
152.8
154.2
154.4
153.8
153.6
153.4
153.8
153.7
155.2
153.8
153.5
153.6
154.0
152.8
Cnt
92
94
93
95
95
94
95
94
95
94
95
94
95
93
95
94
94
94
95
94
95
95
94
93
95
94
94
94
94
94
95
2921
2009 - 2014 Daily Average HPIC Readings
200
180
160
140
μR/hr
120
100
PIC 1
80
PIC 2
60
40
20
4/1/2014
1/1/2014
10/1/2013
7/1/2013
4/1/2013
1/1/2013
10/1/2012
7/1/2012
4/1/2012
1/1/2012
10/1/2011
7/1/2011
4/1/2011
1/1/2011
10/1/2010
7/1/2010
4/1/2010
1/1/2010
10/1/2009
7/1/2009
4/1/2009
1/1/2009
0
This chart shows relatively stable readings with an increase in 2013. This increase was due to the
placement of 6 casks to the ISFSI from April to June 2013.
4