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 February 2012.
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 February 2012, 29 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
December 17, 2010.
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 February 1, 2012 to February 29, 2012 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 was not working in February. Pressurized Ionization Chamber No. 2 was working properly during the
month of February except for February 6 through 11.
Analysis and Comments
Pressurized Ionization Chamber No. 2 readings ranged from 124.1 to 130.6 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 February 2012 Data Report for
Pressurized Ionization Chamber No. 1 Start
Times
Date
Start End
======== ===== =====
======== ===== =====
Dose
(mR)
=====
=====
Intv Status 400v
==== ===== =====
==== ===== =====
2
Avg
Max
Min 6v
(μR/h) (μR/h) (μR/h) Cnt
====== ====== ====== ====== === ====== ====== ====== ====== === Table 2 February 2012 Data Report for
Pressurized Ionization Chamber No. 2
Start
Times
Date
Start End
======== ===== =====
2/1/12
0:12 23:57
2/2/12
0:12 23:46
2/3/12
0:01 23:46
2/4/12
0:01 23:56
2/5/12
0:11 1:26
2/12/12 3:47 23:59
2/13/12 0:02 23:47
2/14/12 0:02 23:57
2/15/12 0:02 23:59
2/16/12 0:14 23:46
2/17/12 0:01 23:57
2/18/12 0:12 23:59
2/19/12 0:14 23:57
2/20/12 0:12 23:56
2/21/12 0:11 23:46
2/22/12 0:01 23:56
2/23/12 0:11 23:46
2/24/12 0:11 23:46
2/25/12 0:01 23:46
2/26/12 0:01 23:46
2/27/12 0:01 23:56
2/28/12 0:11 23:56
2/29/12 0:11 23:27
======== ===== =====
2/1/12 to 2/29/12
Dose
(mR)
=====
3.06
3.06
3.05
3.06
3.06
3.04
3.05
3.05
3.05
3.04
3.04
3.03
3.03
3.03
3.05
3.04
3.03
3.03
3.02
3.01
3.00
3.04
3.06
=====
69.92
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
Status 300v
===== =====
0000
289
0000
290
0000
290
0000
290
0000
290
0000
290
0000
290
0000
290
0000
289
0000
290
0000
290
0000
290
0000
289
0000
290
0000
290
0000
290
0000
290
0000
289
0000
289
0000
289
0000
289
0000
289
0000
289
===== =====
0000
290
3
12v
======
13.17
13.09
13.13
13.12
13.15
13.16
13.18
13.39
13.68
13.79
13.61
13.56
13.73
13.56
13.84
14.14
13.93
13.95
13.93
13.87
13.91
14.12
13.96
======
13.59
Avg
(μR/h)
======
127.6
127.5
127.1
127.7
127.4
126.5
127.1
127.0
127.2
126.6
126.5
126.1
126.3
126.1
127.2
126.6
126.2
126.1
126.0
125.5
125.0
126.7
127.5
======
126.7
Max
(μR/h)
======
128.5
128.1
127.8
128.7
127.6
127.4
128.1
127.9
128.6
127.7
127.4
127.0
127.8
128.5
129.0
127.7
127.0
127.0
126.7
126.2
125.8
130.6
130.6
======
130.6
Min
(μR/h) Cnt
====== ===
127.0
93
126.8
93
126.6
95
126.6
94
127.3
6
125.6 117
126.0 189
126.1 190
125.8 101
125.5
93
125.1
94
125.1
92
124.8
94
124.8
94
126.2
92
125.6
95
125.1
94
125.5
94
125.0
95
124.9
95
124.1
94
124.8
94
125.1
92
====== ===
124.1 2290
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
μR/hr
2009 - 2012 Daily Average HPIC Readings
160
140
120
100
80
PIC 1
PIC 2
60
40
20
0
4