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 August 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 August 2014, 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 August 1, 2014 to August 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 August. Pressurized Ionization Chamber No. 2 was working properly during the month of
August.
Analysis and Comments
Pressurized Ionization Chamber No. 2 readings ranged from 158.8 to 172.2 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: August 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: August 2014 Data Report for Pressurized Ionization Chamber No. 2
Start Date
Start
Times
8/1/2014
0:14
8/2/2014
0:00
8/3/2014
0:11
8/4/2014
0:14
8/5/2014
0:14
8/6/2014
0:02
8/7/2014
0:14
8/8/2014
0:01
8/9/2014
0:00
8/10/2014
0:11
8/11/2014
0:01
8/12/2014
0:14
8/13/2014
0:14
8/14/2014
0:01
8/15/2014
0:01
8/16/2014
0:13
8/17/2014
0:13
8/18/2014
0:14
8/19/2014
0:11
8/20/2014
0:01
8/21/2014
0:14
8/22/2014
0:11
8/23/2014
0:13
8/24/2014
0:11
8/25/2014
0:14
8/26/2014
0:01
8/27/2014
0:11
8/28/2014
0:14
8/29/2014
0:14
8/30/2014
0:14
8/31/2014
0:13
8/1/14 to 8/31/14
End
Times
23:45
23:56
23:59
23:59
23:47
23:59
23:46
23:45
23:56
23:46
23:59
23:59
23:46
23:46
23:59
23:58
23:59
23:56
23:46
23:59
23:56
23:59
23:57
23:59
23:46
23:56
23:59
23:59
23:59
23:59
23:59
Dose
(mR)
3.85
3.84
3.84
3.84
3.84
3.85
3.84
3.84
3.84
3.84
3.85
3.86
3.89
3.89
3.89
3.90
3.94
3.93
3.92
3.92
3.93
3.91
3.93
3.92
3.92
3.91
3.90
3.93
3.95
3.93
3.92
120.5
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
282
283
283
283
282
282
282
282
282
283
283
283
283
283
283
283
286
300
287
284
294
284
291
288
300
282
282
283
300
328
283
287
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)
160.3
160.2
160.1
160.2
160.2
160.3
160.2
159.8
160.0
159.9
160.3
161.0
162.1
162.0
162.2
162.6
164.0
163.8
163.3
163.2
163.7
163.1
163.6
163.3
163.2
162.8
162.6
163.8
164.6
163.9
163.3
162.0
Max
(uR/h)
161.4
161.5
161.2
161.1
161.3
161.5
161.4
160.6
161.1
160.7
161.4
162.5
163.6
162.9
163.2
163.3
172.2
166.9
164.3
164.1
168.6
163.8
166.3
164.8
164.1
163.4
163.4
167.4
171.2
170.9
167.4
172.2
Min
(uR/h)
159.3
159.0
159.0
159.3
159.3
159.0
159.0
158.9
159.2
158.8
159.5
159.4
160.9
161.1
161.2
161.7
162.1
162.1
162.2
162.2
162.5
162.2
162.8
162.1
161.8
161.7
161.5
162.7
162.5
162.2
162.2
158.8
Cnt
94
96
94
95
95
95
95
94
96
94
92
94
94
95
95
95
92
95
93
93
95
94
95
94
94
96
94
92
95
95
94
2924
2009 - 2014 Daily Average HPIC Readings
200
180
160
140
μR/hr
120
100
PIC 1
80
PIC 2
60
40
20
7/1/2014
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