ML20248K191

Rev 1 to App D, Special Ground & Well Water Samples, of 1995 Annual Radiation Environ Monitoring Program Rept

ML20248K191
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Site:	Prairie Island
Issue date:	12/31/1995
From:	NORTHERN STATES POWER CO.
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Praire Island Nuclear RADIATION ENVIRONMENTAL Rev.1 Generating Plant MONITORING PROGRAM 1995 ANNUAL REPORT Appendix D l

l APPENDIX D l

Special Ground and Well Water Samples o%

9906100023 990515-D-1 PDR ADOCK 05000282 PM R

Praire Island Nuclear RADIATION ENVIRONMENTAL Rev.1 Generating Plant MONITORING PROGRAM 1995 ANNUAL REPORT Appendix D

1.0 INTRODUCTION

This revision corrects the tritium numbers from October 1994 through 1995 that were reported in Tritium Units instead of pCi/L. One (1) Tritium Unit equals 3.2 pCi/L. All previously reported tritium numbers from October 1994 through 1995 have been multiplied by 3.2.

This appendix to the Radiation Environmental Monitoring Program Annual Report to the United States Regulatory Commission summarizes and interprets results of the special well and seepage water samples taken at the Prairie Island Nuclear Generating Plant, Red Wing, Minnesota, during the period January - December,1995. This supplemental special sampling program was established in December of 1989 when higher than expected levels of tritium were detected in a nearby residence well sample.

Tabulations of the special sampling program individual analyses made during the year are included in this appendix. A summary table of tritium analyses is also included in this appendix.

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Praire Island Nuclear RADIATION ENVIRONMENTAL Rev.1 Generating Plant MONITORING PROGRAM 1995 ANNUAL REPORT Appendix D 2.0

SUMMARY

This special sampling program was established following the detection of tritium in a residence well water sample south of the PINGP during 1989. This program is described and the results for 1995 are summarized and discussed.

Program findings for 1995 detect low levels of (ritium in nearby residence wells and some ground water seepage samples at or near the expected natural background levels. The 1995 sample results ranged from 48 pCi/L to 352 pCi/L. All tritium results are far below the Environmental Protection Agency's drinking water standard of 20,000 pCi/L and present no harm to any members of the public.

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Praire Island Nuclear RADIATION ENVIRONMENTAL Rev.I Generating Plant MONITORING PROGRAM 1995 ANNUAL REPORT Appendix D 3.0 Snecial Tritium Samnling Program 3.1 Program Design and Data Intemretation The purpose of this empling program is to assess the impact of any tritium leaching into the environment (ground water system) from the PINGP discharge canal. For this purpose, special water samples are collected and analyzed for radioactive content.

3.2 Program Description The sampling and analysis schedule for the special water sampling program is summarized in Table 4.1 and briefly reviewed below. Table 4.2 defines the additional sample locations and codes for the special water sampling program.

Special well and ground water samples were collected semi-annually at eight locations:

one sample from the PINGP Environmental Laboratory (P-30); one from the nearest residence deep well (P-24d, Suter residence); two ground water seepages from near Birch Lake (P-31 and P-32); well water from the Prairie Island Training Center (P-26); and three other nearby residences (P-27, Nauer residence; P-28, Allyn (Perkins) residence; P-29, Childs residence). The Rohl farm well (part of the quarterly REMP sampling) is used as a control location for these special samples.

In order to detect low levels of tritium at or below natural background levels, analyses of the samples have been contracted to a labore ry (University of Waterloo Laboratories) capable of detecting tritium concentrations down to 19 pCi/L.

3.3 Program Execution The special water sampling was executed as described in the preceding section.

3.4 Program Modifications The frequency of sampling was changed from quarterly to semi-annually. Due to slow migration of the ground water,it is adeqtate to sample semi-annually.

l 3.5 Results and Discussion Results obtained show tritium in well water and ground water samples at or near expected natural background levels. Table 4.4 provides the complete data table of results for each quarter and sampling location.

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Praire Island N'uclear RADIATION ENVIRONMENTAL Rev.1 Generating Plant MONITORfNG PROGRAM 1995 ANNUAL REPORT Appendix D l

The tritium level annual averages have shown a downward trend since the special sampling begun in 1989. Annual averages for the nearest resident south of the plant were: 1430

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pCi/L in 1989,1360 pCi/L in 1990, 960 pCi/L in 1991,835 pCi/L in 1992,516 pCi/L in 1993,370 pCi/L in 1994 and 170 pCi/L in 1995.

The 1995 levels are near or within the range of expected background tritium levels in shallow ground water and surface water due to tritium concentrations measured in precipitation. Sampling points in Nonh America have shown tritium concentrations in precipitation ranging from 5 pCi/L to 157 pCi/L (Environmental Isotope Data No.10; World Survey ofIsotope Concentration in Precipitation (1988-1991)).

The higher level results at Suter and Birch Lake in 1989 were possibly due to seepage from the PINGP discharge canal water into the ground water. This is thought to occur due to the elevation difference between the Vermillion River and the discharge canal. The Suter residence is located between the discharge canal and Birch Lake, which connects to the Vermillion River. The PINGP discharge canal piping was lengthened during 1991, so that liquid discharges from the plant are released near the end of the discharge canal, diffused J

and discharged to the Mississippi River. In 1992, the underground liquid discharge pipe

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from the plant to the discharge canal piping was replaced with a double walled leak

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detectable piping system. It is expected that these modifications will climinate the j

suspected radioactive effluent flow into the local ground water. The 1995 trend supports this expectation.

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Praire Island Nuclear RADIATION ENVIRONMENTAL Rev.1 Generating Plant MONITORING PROGRAM 1995 ANNUAL REPORT Appendix D Table D-4.1 Sample collection and analysis program for special well and seepage water samples, Prairie Island Nuclear Generating Plant,1995.

Medium No.

Location codes Collection type Analysis typec and frequencyb and typea Well water 7

P-24d, P-25 (C),

G/SA H-3 semi-annual P-26, P-27, P-28, P-29, P-30 Ground water 2

P-31, P-32 G/SA H-3 a Location codes are defined in table D-4.2. Control Station are indicated by (C). All other stations are indicators.

I b Collection type is codes as follows: C/ = continuous; G/ = grab. Collection frequency is coded as follows: W = weekly; M = monthly; Q = quarterly; SA = semi-annually; A =

annually; X = no specified frequency or one time.

c Analysis type is coded as follows: GB = gross beta; GS = gamma spectroscopy; H-3 =

tritium; I-131 = iodine 131.

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r Praire Island Nuclear RADIATION ENVIRONMENTAL Rev.1 Generating Plant MONITORING PROGRAM 1995 ANNUAL REPORT Appendix D Table D-4.2.

Sampling locations for special well and seepage water samples, Prairie Island Nuclear Generating Plant,1995.

l Code typea Collection site Type of sampleb Distance and direction from reactor l

P-24d Suter residence, deep well WW 0.6 mi. @ 158'/SSE P-25 C

Rohl farm WW 12.9 mi @ 352 /N P-26 PITC WW 0.4 mi. @ 258 /WSW P-27 Nauer residence WW 0.9 mi. @ 154 /SSE P-28 Allyn (Perkins)

WW l.0 mi. @ 152 /SSE residence P-29 Childs residence WW l.2 mi. @ 149 /SSE P-30.

PINGP Environmental Laboratory WW 0.2 mi. @ 32 /NNE P-31 Birch Lake Seepage #1 GW 0.7 mi. @ 179 /S P-32 Birch Lake Seepage #2 GW 0.8 mi. @ 169'/SSE a "C" denotes control location. All other locations are indicators.

b Sample codes: WW = Well water; GW = Ground Water.

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Praire Island Nuclear RADIATION ENVIRONMENTAL Rev.1 Generating Plant MONITORING PROGRAM 1995 ANNUAL REPORT

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Appendix D Table D4.3 Radiation Environmental Monitoring Program Summary: Special well and scepage water samples.

Name of Facility Prairie Island Nuclear Power Station Docket No.

50-282,50-306 Location of Facility Goodhue, Mmnesota Reporting Period January. December 1995 (County, State)

Indicator Location with thghest Control Number Sample Type and Locations Semi-Annual Mean Locations Non-Type Number of Ltob Mean (F)c Mean (F)*.

Mean (F)e Routine (Units)

Analyses Range Range e

L cationd a

c Range Results' Well Water 11-3 14 19 160 (10/12)

P-28, 250 (2/2) 64 (2/2) 0 (pCi/L)

(54-310)

Allyn well, (186-310)

(54-74) 0 1.0 mi. @ l52 /SSE Ground Water H-3 6

19 298 (4/4)

P-31, Birch Lake 320(2/2) 64 (2/2) 0 (pCi/L)

(221-352)

Scepage #1, (285-352)

(54 74) 0.7 mi. @ 179 /S a

11-3 = tritium l

b LLD = Nominal lower limit of detection based on 4.66 sigma error for background sample. Value shown is lowest for the period.

Mean and range ar based on detectable measurements only. Fraction of detectable measurements at specified locations is indicated in parentheses (F).

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d Locations are specified: (1) by name, and code (Table 2) and (2) by distance, direction and sector relative to reactor site.

• Non-routine results are those which exceed ten times the control station value.

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Praire Island Nuclear RADIATION ENVIRONMENTAL Rev.I l

Generating Plant MONITORING PROGRAM 1995 ANNUAL REPORT Appendix D l

I Table D-4.4 Radiological Environmental Monitoring Program, Complete Data Table, l

1995.

SAMPLE DATES APR.1995 JUN.1995 SEP.1995 OCT.1995 SAMPLE LOCATIONS pCi/L pCi/L pCi/L pCi/L Suter residence 246 93.

Rohl Farm (Control) 74 54 PITC 118 131 Nauer residence 86 48 Allyn (Perkin) residence 310 186 Child residence 240 147 Environmental Lab

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<19 Birch Lake Seepage #1 285 352 Birch Lake Seepage #2 336 221 D-9 I