ML20138A790
| ML20138A790 | |
| Person / Time | |
|---|---|
| Issue date: | 11/30/1985 |
| From: | Wescott R Office of Nuclear Reactor Regulation |
| To: | |
| References | |
| ESRP-7.1.1, NUREG-1165, NUDOCS 8512120111 | |
| Download: ML20138A790 (13) | |
Text
--
l NUREG-1165 Environmental Standard Review Plan for ES Section 7.1.1 Environmental Impacts of Postulated Accidents Involving Releases of Radioactive Materials to Groundwater U.S. Nuclear Regulatory Commission 1
Office of Nuclear Reactor Regulation November 1985 l
l
$R REGU r
s 7.
tj
\\...../
- !A2 8Ai!85223o 1165 R PDR
. _, _.. -.. - - _ - _ _ _ -.. -. ~ _. _. _.. _ ~ _ _ - -, _ - - -. _ - - - -. - _. - - - - - - - -
Section 7.1.1 ENVIRONMENTAL STANDARD REVIEW PLAN FOR ES SECTION 7.1.1 ENVIRONMENTAL IMPACTS OF POSTULATED ACCIDENTS INVOLVING RELEASES OF RADI0 ACTIVE MATERIALS TO GROUNDWATER REVIEW INPUTS Environmental Report Sections 2.1.3 UseofAdjacentLandsandWaters 2.4 Hydrology 2.5 Geology Environmental Reviews 2.3 Water (ESRP Section)
Standards and Guides Interim Policy Statement NUREG-0440, " Liquid Pathway Generic Study" NUREG-1054, " Simplified Analysis for Liquid Pathway Studies" Other Site visit Responses to requests for additional information Consultation with local, State, and Federal agencies Applicant's Safety Analysis Report REVIEW OUTPUTS Environmental Statement Sections 5.9 Radiological Impacts 5.9.4 Environmental Impacts of Postulated Accidents 5.9.4.5 Accident Risk and Impact Assessment 5.9.4.5(5) Releases to Groundwater Other Environmental Reviews l
None L
7.1.1-1
I.
PURPOSE AND SCOPE The purpose of this environmental standard review plan (ESRP) is to direct the staff's review of the radiological effects that could result from a core-melt accident by way of the groundwater pathway.
Tha scope of the review djrected by this plan will include consideration of sufficiently detailed site-specific and regional data on groundwater and surface water hydrology and water use, which will be used to calculate probable doses to humans from a core melt released to the groundwater through such liquid pathways as drinking water, aquatic food ingestion, and shoreline exposure.
II.
REQUIRED DATA AND INFORMATION The kinds of data and information required will be affected by site specific factors, including the potential consequences resulting from a
-core melt at that site. The following data and information could be required depending on the pathway components identified as major contributors to dose:
A.
General 1.
Core melt radiological source terms.*
2.
Maps of sufficient detail to show the relationship of the site to major hydrological systems that could be impacted by the groundwater pathway from a core-melt accident.
" Plant-specific or probabilistic source terms must be reviewed and approved by the appropriate staff technical branches.
An acceptable default value may be obtained from the Liquid Pathway Generic Study (Refs. 1 and 2). Ongoing research is expected to result in improved default values.
7.1.1-2 l
l n
3.
Locations of downstream surface water users, as well as population using downstream municipal supplies.
4.
Locations of downgradient groundwater users, as well as 3
population using downgradient municipal supplies, if any.
5.
Estimates of downstream aquatic food consumption broken down into consumption of finfish and shellfish.
6.
Shoreline use of downstream water bodies.
The term " downstream" here is used to also mean upcoast and downcoast, and offshore in the case of Great Lakes, estuary, and coastal sites.
B.
Groundwater 1.
Descriptions of geologic formations in the site region and underlying the site.
Descriptions should include areal extent,. elevation, and thickness of aquifers; recharge and discharge areas; and lithology.
Descrip-tions should be sufficiently detailed to adequately identify aquifers and aquicludes.
f 2.
Piezometric contour maps and hydraulic gradients (from the ER, SAR, and general literature).
3.
Hydraulic conductivities or transmissivities, storage coefficients or specific yields, total and effective porosities, bulk
~
' densities, and distribution coefficients for strontium and cesium.
i 4.
Interactions between surface water and groundwater near the site.
7.1.1-3 l
C.
Surface Water 1.
River Sites a.
Harmonic mean of daily flows for downstream reaches.
Reaches must correspond to those for which water users were determined. The procedure for determining this mean is given in NUREG-1054 (Ref. 1).
b.
Sedimentation parameters for reservoirs, such as sediment depth, density, deposition' rate, efficiency, equilibrium coefficient, and bottom transfer coeffi-cient. These data are optional.
2.
Great Lakes Sites a.
Volume and inflow for lake on which site is situated and downstream lakes.
b.
Sedimentation parameters for lakes, such as sediment depth, density, deposition rate, efficiency, equilibrium coefficient, and bottom transfer coefficient.
3.
Estuary Sites a.
Salinity and freshwater flow for all segments used to define estuary and salinity in seawater outside of estuary.
Segments must correspond to those for which aquatic food catch and shoreline users were determined.
7.1.1-4 f
?
b.
Dilution factors for the segments determined by other means than salinity ratio. These data are optional.
c.
Sedimentation parameters for segments, such as sediment depth, density, deposition rate, efficiency, equilibrium coefficient, and botton transfer coefficient.
These data are optional.
4.
Coastal Sites a.
Longshore drift current velocity, and effective water depth off shore.
III.
ANALYSIS PROCEDURE The analysis of the groundwater pathway should begin with a review of the geologic formations underlying the site as well as the soil and backfill around and underneath the reactor building.
The molten core is assumed to melt to a level 50 feet below the basemat unless the site geology or heat transfer considerations can be shown to indicate otherwise.
Hence, any l
permeable layer between the ground surface and 50 feet below the basemat should be considered a potential pathway for movement of radionuclides.
If the release is into a known or suspected leaky aquifer, then even deeper permeable layers (below 50 feet) should be considered as potential pathways.
The most critical pathways are generally those that lead to surface water bodies or large municipal water supplies.
l l
Once the major groundwater pathway (s) is identified, travel times to I
nearby downgradient municipal or industrial groundwater users or surface water bodies should be determined.
The shortest travel time, which should not include the effects of retardation, is an indicator of the l
l 7.1.1-5 1
i
minimum time available for mitigation following an accident.
Longer travel times, taking into account the effects of the ion-exchange of strontium and cesium with the pathway medium, should also be calculated.
These travel times will then be used to determine what fraction of the initial release of cesium-137 and strontium-90 will be available to provide a dose to humans after radioactive decay.
It should be recognized that for short groundwater travel times (less than about 1 year), other radionuclides may contribute significantly to the dose.
For longer travel times, however, only the relatively long-lived cesium-137 and strontium-90 need be considered for dose estimates.
In determining groundwater travel times, it is often necessary to use hydrogeologic data obtained from the site investigation.
These data should consist of hydraulic conductivity as well as effective and total porosity values for the various soil and rock formations.
For those formations likely to be pathways for radionuclide movement, hydraulic gradient and retardation coefficients should also be provided.
The values assumed in the analysis should be conservative representations of the measured data.
An acceptable means of checking the reasonableness of the measurements taken at the site, if there appears to be considerable uncertainty or inconsistency in the measurements, is to compare the values with ranges of values determined for similar geologic media as presented in References 1, 3, 4, and 5 or other generally accepted geohydrologic texts and technical papers.
The type of analysis performed once the radionuclides enter a surface water body depends on whether the surface water body is a river, estuary, ocean, or Great Lake.
If the water body is a river and contains downstream reservoirs, the reservoirs may require special consideration.
However, the following overall steps for determining population dose are the same.
7.1.1-6
A.
Determine the amount of radionuclide to which humans could be exposed over infinite time.
For any particular radionuclide, this is a function of the inventory that escapes the reactor building, the fraction of the above inventory that escapes through the groundwater system, and the dilution and removal mechanisms in the surface water system.
B.
Determine how much of the available radionuclide released to the ground actually contributes to population dose.
This is a function of urinking water ingested, aquatic food ingested, and shoreline use of the water bodies downstream of the site.
C.
Use dose conversion factors to convert the amount of radionuclide ingested or to which humans are exposed into dose for the various pathways.
The total population dose from the liquid pathway is then the sum of these pathway doses.
References 1, 2, and 6 present details of models that can be used to determine dilution and rates of removal for the various hydrologic systems.
More sophisticated models, if properly documented, are also acceptable.
References 1 and 2 also give detailed guidance for determining.the total population dose on the basis of drinking water use, aquatic food ingested, j
and shoreline exposure.
l
(
As an option, the analysis also may be performed taking probabilities of releases into account and determining the probabilities of consequences.
This may require the probabilities and inventory release fractions for various types of accident sequences, the probability that the core melt I
may breach the basemat for the various types of accident sequences, and the probability of occurrence of hydrologic variations that could 7.1.1-7
significantly influence dose, such as flow in rivers or level in reservoirs for short-duration releases.
All probabilities should be adequately documented.
The final result of the probabilistic groundwater pathway analysis is a value for the total risk from the groundwater pathway.
The total risk represents the sum of the products of the consequences and probabilities of the various accident sequences that could result in a groundwater release and hydrologic variations where appropriate.
At this time, there does not appear to be any definitive guidance on how to assess the probability of a breach in the basemat; therefore, the rationale for any probabilities assumed should be adequately explained.
IV.
EVALUATION The reviewer *;il! ensure that (1) data are sufficient to provide reasonably accurate or conservative analyses regarding groundwater pathways and travel time and (2) all actual downstream water uses and users that could be a significant pathway have been included in the population dose calculations.
It is permissible, however, for the reviewer to take into account evaluations showing that one or more of the hydrologic pathways will be insignificant when compared with the other pathways and therefore need not be considered further.
For example, where conservatively calculated groundwater holdup times result in radioactive decay of almost all the available strontium-90 and cesium-137, it is permissible to end the analysis at that point,. concluding that the groundwater pathway will be insignificant when compared with other pathways.
7.1.1-8
-.. ~
t l
The reviewer should then make an independent calculation of the t
I population dose using the simplified. procedures in NUREG-1054 (Ref. 1) where h
~ appropriate. The result, although conservative in most cases, will be
. integrated into the total plant risk analysis after transmittal as input to the Environmental Statement. This result should also be compared with
{
the total population dose for the corresponding generic site as presented in Table 6.1'of.NUREG-1054.
A finding that the potential groundwater l
pathway doses are significantly greater than the doses at the generic site may indicate that the probabilistic study will be required.
1 1
.If a probabilistic analysis is available for the initial review, the comparison with the generic site need not be made.- Instead, the total risk contribution from the groundwater pathway should be presented for i
integration into the entire accident analysis.
V.
INPUT TO THE ENVIRONMENTAL STATEMENT The input to the Environmental Statement should consist of a description i
of the analysis in sufficient detail to allow an independent appraisal of.the relative conservatism of the analysis.
i h
The input should consist of a brief description of the hydrosphere l
(surface and groundwater) pertinent to'the liquid pathway and dose assessment.-
The section on groundwater description in the Environmental Statement or the applicant's. Environmental Report may be referred to for greater detail.
t
-The description of.the hydrosphere should be followed by a description of the analysis procedures and the values of the parameters used by the 3 -
applicant. The description should include statements regarding the accept-l 7.1.1-9 4
. - ~...
~
~. -
ability of these values and procedures to the staff.
If NUREG-1054 procedures are used, then the description of the procedures should be brief and NUREG-1054 should be referenced.'
The input should then include the calculated dose values and a statement comparing the site-specific dose with the dose for the generic If the prob'bilistic assessment was performed, cases in terms of a ratio.
a only the totaf groundwater pathway risk should be stated, the comparison with the~ generic site is not applicable.
The input should close with a brief statement on the feasibility of groundwater pathway mitigation measures at the site.
In determining feasibility,. groundwater travel time and site geology should be taken into account.
VI.
REFERENCES-1.
R. Codell, Simplified Analysis for-Liquid Pathway Studies, U.S'.
Nuclear Regulatory Commission, NUREG-1054, August 1984.
2.
U.S. Nuclear Regulatory. Commission, Liquid Pathway Generic Study, NUREG-0440, February 1978.'
3.
D. K. Todd, Groundwater Hydrology,' John Wiley-and Sons, New York, I
New York,' 1980.
4.
R. A. Freeze and J. : A. Cherry,--Groundwater, Prentice Hall, Inc.,
l EhglewoodCliffs,NewJersey,1979.
=;
7.1.1-10
5.
D. Isherwood, Geoscience Data Base Handbook for Modeling a Nuclear Waste Repository, U.S. Nuclear Regulatory Commission, NUREG/CR-0912,Vol. 1, January 1981.
6.
R. Codell, K. T. Key, and G. Whelan, A Collection of Mathematical Models for Dispersion in Surface Water and Groundwater, U.S. Nuclear Regulatory Commission, NUREG-0868, June 1982.
l i
7.1.1-11
uaNuctE m n uu.ToavcO.. ON i*E.oiTNuou w.
r,0c.
v,.....a.,
g,*0a===
%'"3A','-
BIBUOGRAPHIC DATA SHEET NUREG-1165 (ESRP 7.1.1)
SEE INSTRuCTsONS ON YME #IEVEmSE 2 YITLE AND 5uSIsTLE 3 LE AVE 9tANE ESRP 7.1.1
" Environmental Impacts of Postulated Accidents Involving Releases of A oATE.E,0,cO,uTEo Radioactive Materials to Groundwater" l
.Ou -
vEaa
.,.uT,.O. <s, October 1985 6 DATE REPORT IS5uED Rex G. Wescott l
November 1985 7 e inFOmuaNG Omsami2 AT SON N AME AND MasLING ADDRES5 ftae48el, c,,,j e PROJECT,T ASE. WORE UNei NuM8ER M40047 Division of Engineering
..iN O. Ga ANT Nuon a Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, D.C.
20555
- 10. $PONSOmiNG ORGANi2ATiON Navt AND MAILING ADDRESS traebesle Ca8rt i t. TYPE OF REPORT (Same as 7 above).
FINAL e PE RiOD COV E RED startess v. alefest 12 $UPPLEWENTARY NOTES 11 ASSYr.ACT (200 more er w Environmental Standard Review Plan (ESRP) 7.1.1 provides guidance to the staff for preparation of environmental assessments of " Radiological Impacts - Releases to Groundwater," an input to the staff's environmental ' statement which addresses the groundwater pathway consequences from postulated reactor core-melt accidents.
The ESRP lists the type of information which should be collected, references that may be useful, and provides a procedure for uniform staff review of applicant analyses.
The ESRP is applicable to both Construction Permit and Operating License Stage reviews.
l
[
- i. oOcumeNT ANatvs.s -. Ev O DsiotscRiPYoas is Liquid Pathways v,Agiu Y v Groundwate..
Unlimited Radionuclide Transport 16 SECURITY CLAS$1FICATION
< r.
. OEc. if asiOPEN ENoto TEaws Unclassified a r..
r,,
Unclassified IP NuMSER OF PAGES
..,.ic E l
2 l2
_s m
Z UNITED STATES rouavnetess ucit C
'oStac56'H5'**
NUCLEAR REGULATORY COMMISSION M
usmac WAShlNGTON, D.C. 20555 wass o c m
esaun o er o
b OFFICIAL BUSINESS
.I203
/
PENALTY FOR PRIVATE USE,4300 US jg >O 766 77 POLIfy &
IV GF A N3 3 g T
W Pog* C
,~503 "A SH yy!G T bR-PDg O?;
,.UR C G DC
~
<C55 2
x O
2E m2H r
~
(
r s
m
-i s
s 2
o m
4 O
4 m<
s ll1
~
4, y
44 h
z T.
Y.3 s.
m v
m Cfh m
O d
O Z
N b.
\\
s, 4
N 4-
,w et 4 '.
s.
~
N s\\
\\2 O
A;
\\
mE x
tm x
m
.%s
3 s
g kg h
4 r
- ' = ~
~ - ' ' ' ' ' '
^ ~
~~