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 April 2015. 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 April 2015, 38 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
August 12, 2014.
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 April 1, 2015 to April 30, 2015 and are summarized in Table 1. 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 April. Pressurized Ionization Chamber No. 2 was working properly during the month of April.
Analysis and Comments
Pressurized Ionization Chamber No. 2 readings ranged from 153.4 to 160.8 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: April 2015 Data Report for Pressurized Ionization Chamber No. 2
Start Date
4/1/2015
4/2/2015
4/3/2015
4/4/2015
4/5/2015
4/6/2015
4/7/2015
4/8/2015
4/9/2015
4/10/2015
4/11/2015
4/12/2015
4/13/2015
4/14/2015
4/15/2015
4/16/2015
4/17/2015
4/18/2015
4/19/2015
4/20/2015
4/21/2015
4/22/2015
4/23/2015
4/24/2015
4/25/2015
4/26/2015
4/27/2015
4/28/2015
4/29/2015
4/30/2015
4/1/15 to
4/30/15
Start
Times
0:11
0:01
0:11
0:11
0:11
0:11
0:01
0:11
0:01
0:11
0:01
0:11
0:11
0:11
0:11
0:11
0:01
0:11
0:11
0:11
0:11
0:11
0:11
0:01
0:11
0:00
0:11
0:01
0:11
0:11
End
Times
23:46
23:56
23:56
23:56
23:56
23:46
23:56
23:46
23:56
23:46
23:56
23:56
23:56
23:56
23:56
23:46
23:56
23:56
23:56
23:56
23:56
23:56
23:46
23:56
23:46
23:56
23:46
23:56
23:56
23:56
Dose
(mR)
3.75
3.74
3.75
3.75
3.75
3.74
3.75
3.75
3.79
3.76
3.73
3.73
3.73
3.72
3.72
3.71
3.72
3.72
3.75
3.76
3.75
3.74
3.73
3.75
3.72
3.72
3.71
3.72
3.71
3.71
112.0
Intv
Status
300v
12v
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
272
272
268
270
270
269
268
269
269
269
272
274
273
272
273
274
275
274
273
270
269
270
270
270
272
272
273
273
274
274
271
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
0
2
Avg
(uR/h)
156.3
156.0
156.2
156.1
156.2
156.0
156.3
156.2
157.8
156.7
155.6
155.3
155.3
155.1
154.9
154.7
154.9
155.1
156.2
156.8
156.3
155.7
155.4
156.1
155.2
155.0
154.7
155.0
154.7
154.5
155.7
Max
(uR/h)
160.8
158.9
157.0
157.3
157.3
156.7
158.9
156.9
160.7
158.4
157.2
156.4
157.7
156.9
156.3
155.5
156.4
156.6
157.9
158.6
157.0
156.6
157.2
158.1
156.1
156.5
156.3
156.8
156.0
155.7
160.8
Min
(uR/h)
154.3
154.8
155.3
155.1
155.3
155.3
155.4
155.7
156.3
155.0
154.4
154.2
154.2
153.7
153.8
153.8
153.6
153.8
154.8
156.0
155.7
154.5
154.0
155.0
154.2
153.6
153.4
153.7
153.4
153.4
153.4
Cnt
95
95
96
95
94
95
95
94
95
95
95
93
94
96
95
95
95
94
96
93
96
94
94
95
95
96
94
95
96
94
2844
3
1/1/15
4/1/15
10/1/14
7/1/14
1/1/14
4/1/14
10/1/13
7/1/13
1/1/13
4/1/13
10/1/12
7/1/12
4/1/12
1/1/12
10/1/11
7/1/11
1/1/11
4/1/11
10/1/10
7/1/10
1/1/10
4/1/10
10/1/09
7/1/09
1/1/09
4/1/09
10/1/08
7/1/08
4/1/08
1/1/08
μR/hr
2009 - 2015 Daily Average HPIC Readings
200
180
160
140
120
100
PIC 1
80
60
PIC 2
40
20
0