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 2013. 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 2013, 31 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
April 23, 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 April 1, 2013 to April 30, 2013 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 only worked a
few days in April. Pressurized Ionization Chamber No. 2 was working properly during the month of April.
Analysis and Comments
Pressurized Ionization Chamber No. 1 readings ranged from 104.9 to 122.5 μR/hr. Pressurized Ionization
Chamber No. 2 readings ranged from 120.9 to 135.6 μR/hr. The readings are within the normal ranges of
ambient radiation levels inside the Independent Spent Fuel Storage Installation near the casks (about 100
feet away): 100 to 160 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/environdatareport.html or contact Brandon Juran
at [email protected] or 651-201-4526.
1
Table 1 April 2013 Data Report for
Pressurized Ionization Chamber No. 1
Start
Times
Date
Start End
======== ===== =====
4/15/13 17:27 21:42
4/16/13 0:11 23:59
4/17/13 0:06 5:45
4/21/13 3:08 16:56
======== ===== =====
4/15/13 to 4/21/13
Dose
(mR)
=====
2.88
2.89
2.90
2.91
=====
11.58
Intv
====
900
900
900
900
====
900
Status 400v
===== =====
0000
405
0000
405
0000
405
0000
405
===== =====
0000
405
2
6v
======
6.90
6.84
6.70
6.76
======
6.81
Avg
(μR/h)
======
119.8
120.6
120.8
121.3
======
120.7
Max
(μR/h)
======
121.8
121.3
121.3
122.5
======
122.5
Min
(μR/h)
======
118.5
113.9
111.2
104.9
======
104.9
Cnt
===
18
102
41
23
===
184
Table 2 April 2013 Data Report for
Pressurized Ionization Chamber No. 2
Start
Times
Date
Start End
======== ===== =====
4/1/13
0:01 23:57
4/2/13
0:11 23:56
4/3/13
0:11 23:57
4/4/13
0:11 23:56
4/5/13
0:27 23:58
4/6/13
0:13 23:46
4/7/13
0:01 23:46
4/8/13
0:01 23:57
4/9/13
0:11 23:56
4/10/13 0:11 23:56
4/11/13 0:11 23:46
4/12/13 0:01 23:54
4/13/13 0:11 23:57
4/14/13 0:12 23:56
4/15/13 0:11 23:51
4/16/13 0:11 23:59
4/17/13 0:14 23:57
4/18/13 0:12 23:59
4/19/13 0:16 23:57
4/20/13 0:11 23:56
4/21/13 0:09 23:46
4/22/13 0:01 23:57
4/23/13 0:12 23:56
4/24/13 0:11 23:59
4/25/13 0:14 23:56
4/26/13 0:11 23:56
4/27/13 0:11 23:46
4/28/13 0:01 23:57
4/29/13 0:26 23:56
4/30/13 0:10 23:59
======== ===== =====
4/1/13 to 4/30/13
Dose
(mR)
=====
2.94
2.93
2.93
2.94
2.96
2.96
2.95
2.97
2.99
3.05
3.03
3.03
3.02
3.06
3.00
3.01
3.04
3.07
3.07
3.04
3.05
3.09
3.19
3.17
3.09
3.05
3.04
3.04
3.03
3.03
=====
90.78
Intv
====
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
Status 300v
===== =====
0000
284
0000
284
0000
285
0000
286
0000
285
0000
286
0000
286
0000
286
0000
286
0000
285
0000
285
0000
285
0000
285
0000
285
0000
285
0000
286
0000
285
0000
285
0000
284
0000
285
0000
286
0000
285
0000
285
0000
285
0000
286
0000
287
0000
288
0000
288
0000
288
0000
288
===== =====
0000
286
3
12v
======
14.27
14.27
14.27
14.26
14.27
14.26
14.26
14.26
14.26
14.27
14.26
14.26
14.26
14.26
14.26
14.26
14.26
14.26
14.26
14.26
14.26
14.26
14.26
14.26
14.26
14.25
14.25
14.24
14.25
14.25
======
14.26
Avg
(μR/h)
======
122.3
122.2
122.2
122.5
123.3
123.3
123.1
123.9
124.7
126.9
126.4
126.1
126.0
127.3
125.2
125.5
126.6
127.9
128.0
126.5
127.2
128.7
133.0
132.2
128.7
127.1
126.5
126.6
126.4
126.2
======
126.1
Max
(μR/h)
======
123.1
123.2
123.5
125.4
124.2
124.4
124.3
126.1
128.4
130.0
128.8
127.0
127.0
129.9
126.3
126.4
128.7
129.9
129.7
127.7
129.8
135.6
135.3
135.6
129.7
130.9
127.8
129.6
127.7
127.1
======
135.6
Min
(μR/h) Cnt
====== ===
121.3
95
121.2
95
120.9
94
121.2
95
122.5
94
122.8
94
122.4
95
122.7
95
123.2
95
125.0
94
124.3
94
125.1
95
125.1
95
125.4
94
121.1
95
124.7
94
125.2
94
126.6
95
126.2
94
125.2
95
126.0
94
126.6
95
127.9
94
127.0
94
127.5
95
125.1
94
125.6
94
124.2
96
125.7
94
125.1
94
====== ===
120.9 2835
1/1/2009
2/1/2009
3/1/2009
4/1/2009
5/1/2009
6/1/2009
7/1/2009
8/1/2009
9/1/2009
10/1/2009
11/1/2009
12/1/2009
1/1/2010
2/1/2010
3/1/2010
4/1/2010
5/1/2010
6/1/2010
7/1/2010
8/1/2010
9/1/2010
10/1/2010
11/1/2010
12/1/2010
1/1/2011
2/1/2011
3/1/2011
4/1/2011
5/1/2011
6/1/2011
7/1/2011
8/1/2011
9/1/2011
10/1/2011
11/1/2011
12/1/2011
1/1/2012
2/1/2012
3/1/2012
4/1/2012
5/1/2012
6/1/2012
7/1/2012
8/1/2012
9/1/2012
10/1/2012
11/1/2012
12/1/2012
1/1/2013
2/1/2013
3/1/2013
4/1/2013
μR/hr
2009 - 2013 Daily Average HPIC Readings
160
140
120
100
80
PIC 1
60
PIC 2
40
20
0
4