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 December 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 December 2013, 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 December 1, 2013 to December 31, 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 did not work in December. Pressurized Ionization Chamber No. 2 was working properly during the
month of December.
Analysis and Comments
Pressurized Ionization Chamber No. 2 readings ranged from 165.3 to 187.2 μR/hr. The normal range of
ambient radiation levels inside the Independent Spent Fuel Storage Installation near the casks (about 100
feet away) since additional casks were added earlier this year has been 150 to 180 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: December 2013 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: December 2013 Data Report for Pressurized Ionization Chamber No. 2
Start Date
Start
Times
12/1/2013
0:14
12/2/2013
0:10
12/3/2013
0:01
12/4/2013
0:11
12/5/2013
0:14
12/6/2013
0:01
12/7/2013
0:00
12/8/2013
0:11
12/9/2013
0:01
12/10/2013 0:13
12/11/2013 0:11
12/12/2013 0:13
12/13/2013 0:01
12/14/2013 0:11
12/15/2013 0:01
12/16/2013 0:01
12/17/2013 0:13
12/18/2013 0:11
12/19/2013 0:01
12/20/2013 0:29
12/21/2013 0:13
12/22/2013 0:14
12/23/2013 0:11
12/24/2013 0:13
12/25/2013 0:11
12/26/2013 0:01
12/27/2013 0:11
12/28/2013 0:13
12/29/2013 0:12
12/30/2013 0:14
12/31/2013 0:01
12/1/13 to 12/31/13
End
Times
23:55
23:46
23:56
23:59
23:46
23:46
23:59
23:46
23:58
23:54
23:58
23:46
23:56
23:46
23:46
23:59
23:56
23:46
23:56
23:59
23:59
23:56
23:59
23:55
23:46
23:56
23:58
23:59
23:59
23:46
23:46
Dose
(mR)
4.03
4.07
4.07
4.13
4.09
4.08
4.11
4.15
4.23
4.28
4.16
4.24
4.13
4.11
4.09
4.11
4.19
4.25
4.32
4.25
4.25
4.31
4.22
4.20
4.00
3.99
4.16
4.08
4.13
4.05
4.04
128.5
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
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
277
278
278
277
272
269
268
273
270
272
268
273
274
273
269
272
275
273
274
274
275
274
268
268
274
275
275
276
268
264
266
272
14.2
14.2
14.2
14.2
14.2
14.2
14.2
14.2
14.2
14.2
14.2
14.3
14.3
14.3
14.3
14.3
14.3
14.3
14.3
14.3
14.3
14.3
14.3
14.3
14.3
14.3
14.3
14.2
14.3
14.2
14.2
14.3
3
Avg
(uR/h)
168.1
169.7
169.6
172
170.5
170.2
171.3
173
176.4
178.5
173.5
176.6
172.1
171.4
170.5
171.2
174.7
177.2
179.8
177.1
177
179.7
175.8
174.8
166.8
166.3
173.4
170.2
172
168.7
168.2
172.8
Max
(uR/h)
169
172.8
173.9
178.5
171.6
173
174.2
174.5
178.5
182.7
179.3
180.3
177.3
172.4
171.2
172.5
180.3
185.6
186
177.9
178
185.6
181.5
176.3
174
167.6
187.2
175.5
176.7
170.9
169.5
187.2
Min
(uR/h)
167
168.2
168.6
168.9
168
168.6
168
172.1
173.7
176.5
170.7
171
169.6
170.4
169.5
170.1
169.1
173.7
174.7
176.5
176.2
177.2
170.9
167
165.7
165.3
165.6
168
168.5
167.5
167
165.3
Cnt
94
95
95
94
95
94
96
95
95
95
95
95
93
95
95
95
96
95
96
95
95
96
94
96
94
96
95
94
95
95
94
2942
4
9/1/2013
11/1/2013
9/1/2012
11/1/2012
1/1/2013
3/1/2013
5/1/2013
7/1/2013
9/1/2011
11/1/2011
1/1/2012
3/1/2012
5/1/2012
7/1/2012
9/1/2010
11/1/2010
1/1/2011
3/1/2011
5/1/2011
7/1/2011
9/1/2009
11/1/2009
1/1/2010
3/1/2010
5/1/2010
7/1/2010
1/1/2009
3/1/2009
5/1/2009
7/1/2009
μR/hr
2009 - 2013 Daily Average HPIC Readings
200
180
160
140
120
100
PIC 1
80
60
PIC 2
40
20
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.