ML20059F258
| ML20059F258 | |
| Person / Time | |
|---|---|
| Site: | Big Rock Point File:Consumers Energy icon.png |
| Issue date: | 08/31/1990 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20059F256 | List: |
| References | |
| NUDOCS 9009110162 | |
| Download: ML20059F258 (5) | |
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J' SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION DISCHARGE CANAL DREDGING m
BIG ROCK POINT NUCLEAR' PLANT DOCKET NO. 50-155 Introduction-L By letter dated December 29, 1989, the Consumers Power Company (CPCo) requested approval, pursuant to Section 20.302 of Title 10 of the Code of Federal i
Regulations (CFR), of a proposed method to relocate sediment from the discharge canal at the Big Rock Point (BRP) plant to CPCo property upland in a confined disposal area at the BRP site.
The 500 cubic yards of sediment contain a total radior.uclide ;nventory of 0,9 mci, based on radioactivity absorbed from liquid discharges of licensed material.
i In the submittal, the licensee addressed specific information requested in.
7 accordance with 10 CFR 20.302(a), provided a detailed description of-the licensed
~ material, thoroughly analyzed and evaluated the information pertinent to the effects on the environment of the proposed disposal of the licensed material, and. committed to follow specific procedures to minimize the risk of unexpected l
exposures.
Although the environmental imp'act of the proposed action is well within the dose criteria contained in the Commission's "Below Regulatory Concerns" (BRC) Policy Statement dated July 3, 1990, the licensee has not o
requested, and the staff has not considered, the_ actions described herein to be
-l exempt from NRC regulation.
L 1.0 WASTE-STREAM DESCRIPTION J
BRP routinely disposes of liquid waste by discharging to Lake Michigan in -
accordance with 10 CFR 20.106 within the limits of 10 CFR Part 20, Appendix B, Table II; 10 CFR Part 50, Appendix I; and as controlled through plant Technical Specifications (Docket No. 50-155, Section 13.1).
A fraction of the activity-released is absorbed in the sediment in the discharge canal.. Because of the l.
changing lake level and natural changes in lake bed contour, it'is necessary to 7
. dredge'_the canal to ensure uninhibited flow to Lake Michigan, The dredging will involve relocating between 250 and 500 cubic yards (191 l
to'382 m3) of sediment from the discharge canal to an area on Consumers Power L
property at BRP, The material to be relocated is wet sand and gravel indigenous to the shoreline of northern Lake Michigan.
The sediment is. inert
~
y solid material composed mainly of silica.
There are no chemical hazards R
- associ.ated with this material.
However, radionuclides were detected in this material in'very low concentrations as described below.
- 2. 0 RADIOLOGICAL PROPERTIE_S The' licensee has performed radiological analyses of surface sediment samples scooped from various areas.of the discharge canal, These analyses include L
samples taken annually from 1985 through 1989 as part of Big Rock Point's r
Radiological Environmental Monitoring Program, as well as 10 samples taken in i
9009110162 900831 PDR ADOCK 05000155 P
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June 1989 to ensure samples are representative of activity distributed throughout.
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-the canal.
The'results of these analyses provide an estimate of the activity L
-that_may be contained in the sediment at the time of dredging.
The total J-activity of the sediment (0.9 mci) is based on the time-averaged. activity-concentration encountered in-surface samples (1.25 pCi/g, based on all radionuclides detected).
The time-averaged value (as opposed to the maximum concentration) was used to ccmpute the total quantity of radioactive materials in the sediment, since it reflects the period of radionuclide deposition-(1985-89).
Table 1 lists the principal nuclides identified in the sediment.
Table 1 b'
Nuclide Total Activity (mci)
Sr-90 0.011 s
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Cs-134 0.001 C3-137 0.441 L
Total 0.914 ThelicenseeplanstodredgethecanalbetweenJuneandOctober1990jnd Lannually-thereafter for a 10 year period.
The licensee has committed prior to each future dredging,.to: (1) evaluate radionuclide concentrations and' environmental exposure pathway doses in a manner equivalent' tc, that described.
in the CPCo December 29, 1989,. application (to be incorporated into a future L
revision of the Offsite Dose Calculation Manual (ODCM)), (2) compare such doses L
with:the NRC staff guidelines for onsite disposals listed in Section 4.0 of this 1
Safety Evaluation, and-(3) if the guidelines cannot be met, the disposal of the L
particular dredging shall be deemed to be outside the-scope of the'10 CFR 20.302 review documented herein, and a re-application to the NRC shall be made for the L
dredgings'in question or alternative disposal method pursued.
3.0 PROPOSED DISPOSAL METHOD BRP'will mec'hanically dredge.the sediment from the discharge canal and deposit
.it on CPCo property at BRP in a " confined disposal area." The " confined disposal
,li area" is a bermed site where the dredged mate or-. leach back into the waterway or wetlands." pial would not be allowed to return-i W
The staff of the Consumers Power l
Company plans to perform confirmatory measurements of the dredged material after j
' it is land-spread in its proposed resting place.
Should-these measurements R'
indicate that the levels of radioactivity measured in the preoperational sediment samples were significant underestimates (greater than 25%) of the actual
,g it ITeleconference between A. Masciantonio, et al, of the NRC and J. Beer, et al,,
of CPCo, August 21, 1990.
2Letter from G. R. Mannesto, Department of the Army, Corps of Engineers, h
Jur.e 30, 1989.
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radioactivity of the dredging spoils, CPCo staff will notify the NRC.
The.NRC will then. reassess possible radiation doses and require remedial action as appropriate.- The material will be land-spread at an onsite area immediately;
.j above the " ordinary high water --4" for Lake Michigan.
The " ordinary high.
I water mark" is 580.8 feet, baseo.
ae low water 0;tm of 516.8 feet 11 2
(International Great Lakes Datum ).
4.0 RADIOLOGICAL IMPACTS The licensee has evaluated the following potential exposure pathways to members of the general public from the radionuclides in the dredgings:
(1) external l
exposure caused by groundshine in the disposal site; (2) internal exposure from inhalation of resuspended radionuclides; and (3) internal exposure from ingesting
-ground water. 'The staff has reviewed the licensee's calculational methods and assumptions and finds that-they are consistent with NRC Regulatory Guide 1.109,
" Calculation of Annual Doses to Man from Routine Releases of Reactor Effluents for the Purpose of Evaluating Compliance with 10 CFR Part 50, Appendix I,"
-Revision 1 October 1977; the staff finds the assessment methodology acceptable.
Table 2 lists the doses calculated by the licensee for the maximally exposed member of the public based on a total activity 0.9 mci disposed in the current
. year, as well as the cumulative impact of similar disposals during the subsequent 9 years:
Table 2 Whole Body Dose Received by Maximally' Exposed Individual.
Pathway (mrem / year)* (mrem /10 year)**
.Groundshine 0.0302 0.827 Inhalation 0.00084 0.00867 Groundwater 0.00333 0.033 q
TOTAL 0.0357 0.857 As:shown=in Table 2, the annual dose.from 10 years of dredgings disposal is expected to be on the order of 0.1 mrem'or less (approximately 1 mrem per 10 year period).. Should the annual quantity to be disposed by the methods described herein exceed.the values in Table 1 by as much as a factor of 10, annual doses would be only on the' order of 1 mrem; such doses are a small fraction of the 300 mr_em received annually by members of the general public from sources of i
natural background radiation.
Teleconference between A. Masciantonio, et al., of the NRC and J. Beer et, al.,
of CPCo,' August 21, 1990.
2Letter-from G. R. Mannesto, Department of the Army, Corps of Engineers, June 30, 1989.
- Dose. received in the first year from the first year's disposal.
- Dose received over 10 years from 10 annual disposals.
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p, L 1 The guidelines used by the NRC staff for onsite disposals of licensed material are presented in Table 3, along with the staff's evaluation of how each guideline p
_has.been satisfied.
Table 3 20.302 Guideline
_for Onsite disposal Staff's Evaluation
- 1. The radioactive material should be dis-
- 1. Due to the nature of the posed in a manner such that it is unlikely disposed material, recycling that the material would be recycled.
to the general public is-i not considered likely._
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- 2. Doses to the total body and any body
- 2. This guideline is addressed organ of a maximally exposed individual in Table 2.
(a member of the general public or a non-occupationally exposed worker) from the probable pathways of exposure to the disposed material should be-less than 1 mrem /yr.
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- 3. Doses to the total body and any body organ
- 3. Because the material will be of an inadvertent intruder from the probable land-spread, the: staff con-pathways of exposure should be less than siders the maximally exposed i
5 mrem /y'r.
individual scenario to also address the intruder scenario 4.' Doses to the total body and any body organ
- 4. Even if recycling were to' occur of an, individual from ass!aed recycling of after release from regulatory
- the'_ disposed material _ at the time the disposal control, the dose to the max-i site is released from regulatory control-from imally exposed member of the all likely pathways of exposure should be i'
less than 1 mrem, public_is not expected to ex-p ceed 1 mrem /yr, based on the q
exposure scenarios considered in this analysis.
1 The licensee's procedures and commitments as documented in the submittal are acceptable, provided_that they are permanently incorporated into the-licensee's Offsite Dose Calculation Manual (00CM) as an Appendir and that future modifications be reported to NRC in accordance with the applicable 00CH change protocol.
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1 These guidelines are described in a paper entitled, " Disposal of Slightly Contaminated Radioactive Wastes From Nuclear Power Plants," by E. F. Branagan, Jr.
and.F. J. 'Congel, which was published in CONF-860203, Health Physics Considerations Decontamination Decommissioning, Knoxville, Tennessee, February
-1986..The guidelines are being formalized in an NRC Standard Review Plan section presently under development.
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Based'on-the above findings, the staff finds.the licensee's proposal to dispose-
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of: discharge canal dredgings.onsite in the manner described in the CPCo letter dated December 29, 1989;~to be_ acceptable.
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Principal l Contributor:
John Minns (p.:
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