ML20027B592
| ML20027B592 | |
| Person / Time | |
|---|---|
| Site: | 05000000, Seabrook |
| Issue date: | 08/20/1982 |
| From: | Houston R Office of Nuclear Reactor Regulation |
| To: | Novak T Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML20027A704 | List: |
| References | |
| FOIA-82-406 NUDOCS 8209240492 | |
| Download: ML20027B592 (8) | |
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NUCLE AR REGUL AT ORY C&'.7.11SSION f(;
WAT.HING TON. D C 2M55
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i Docket fio.
50-443 and 50-444 liEi:0RAfiDUM FOR:
Thomas fiovak, Assistant Director for Licensing Division of Licensing FRO:1:
R. Wayne Houston, Assistant Director
,i for Radiation Protectior.
2 Division of Systems Integration
SUBJECT:
RESPONSE TO PUBLIC COMi4EUTS 0i. THE SEABROOK DES
'N is the Accident Evaluation Branch response to the Public coments on the DES assigned to AEB via three memoranda from F. Miraglia dated July 12, 1982, July 13, 1982, and August 2, 1982 (Enclosure 2).
The coments HHS-3 and fiH-1 were transmitted to the Hydrologic and Geo-technical Engineering Branch. Their response will be forwarded as soon as it is received.
This response was prepared by flohan Thadant X28941.
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R Wayne Houston, Assistant Director for Radiation Protection i
sion of Systems Integradon i
Enclosures:
As stated cc:RMattson FMiraglia 0 Wheeler i
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j A-37 Corrected page 5-44 is attached.
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A-38 Corrected page 5-62 is attached.
(Attachment #2) i I
HHS-3 (TobedonebyHGEB) 0
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DLH-5 The Nuclear Regulatory Commission constantly evaluates all reportable incidents at nuclear power plant facilities, and l
has established the Office for Analysis and Evaluation of l
Operational Data to assess the incident reports provided
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by the licensees. As a result of these evalutions, the licensees are, from time to time, required to take steps to i
reduce the occurrences of both minor and major events. An I
j extensive list of requirements was generated in the TMI action i
plan. These requirements are presently being implemented.
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There are other examples, too numerous to list here, of the f
steps that the Commission has taken to prevent the occurrence i
of botn common and low probability accidents. These Commis-sion actions inevitably have increased the awareness, and L
improved the ability of the nuclear plant workers to deal with both minor and major accidents if and when they occur. We, h
therefore, disagree with the commentor's statement that "there L
l is no concrete evidence that nuclear plant workers have im-proved their ability to deal with these accidents when they occur, and there no. concrete evidence to indicate that l
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definitive steps have been taken to prevent the occurrence of the most common accidents." The DES statement in Section 5.9.4.3 that "no accidents have caused any significant individual or collective public radiation exposure, nor any significant contamination of the environment" is based on the observation and records available to us.
In the staff's view, the accident experience base is not large enough to permit a reliable quantitative statistical inference. It is, however, sufficient to make a broader and more general statement that the experience " suggests that significant environmental im-pacts caused by accidents are very unlikely to occur over time periods of a few decades."
NH-1 (TobedonebyHGEB).
NH-2 The population exposures presented in the DES are not based on two hour duration. They are based on the duration of the accident and the population densities projected for the year 2020 (See FES related to the construction permit for Seabrook Station Units 1 and 2, pages 7-1 and 7-2).
The commentor is under the incorrect impression that the staff evaluation s
of the design basis accidents presented on page 5-46 of the DES assumes evacuation. This is not the case. The staff has, however, considered evacuation in the case of accidents more severe than the design basis accidents. The staff discus-1 sion of the evacuation assumptions is presented in Appendix F i
of the DES (NUREG-0895).
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The evacuation time estimate is based upon the staff's review of the applicant's estimates of " clear times" presented in the applicant's Environmental Report (Table 7.7-6 in Chapter 7). Their estimate of evacuation time appears to the staff to be reasonable and has, therefore, been used in the analyses presented in the DES.
Although the staff has not separately addressed the impacts of serious accidents specifically on the salt-marsh ecosystem, the overall economic impacts of accidents presented in the DES is comensurate with the consideration given to the public health and safety. The staff analyses of the economic impacts is based upon the economic model discussed in Appendix VI of the Reactor Safety Study (NUREG-75/014) in Section 12.1.1, and
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includes "the cost of managing a possible evacuation, the cost of temporary accommodation for evacuees, the decrease in the value of interdicted property, and the cost of decontaminating c
the property."
In addition, the staff has evaluated, in the DES, radiological impacts on public health and safety result-ing from all significant exposure pathways to the public.
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The risks to the salt marsh ecosystem will, therefore, be small when compared to the larger risks on the public health
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and safety, and overall economic risks, and would not be expected to alter the conclusions reached in the DES.
i The staff has, in the DES Section 5.9.4.3(3), stated that," no
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l operating license will.be issued to a nuclear facility appli-I
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j cant unless a finding is made by the NRC that the state of on-site and off-site emergency preparedness provides reason-able assurance that adequate protective measures can and will The be taken in the event of a radiological emergency....."
staff will ensure that this policy is implemented prior to issuance of an operating license for the Seabrook facility and adequate emergency response capability is provided at the Seabrook site.
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The population center distance is at least one and one-third times the LPZ outer radius, regardless of whether the nearest population cen-ter were designated to be Portsmouth, Amesbury, or Newburyport.
The transient population associated with seasonal activity at Hampton and Seabrook beaches about 3.2 km (2 mi) east of the site is sufficiently large* that the Atomic Safety and Licensing Appeal Board (ASLAB), in the course of the construction permit hearings, directed that the beach areas to the east of the site be con-sidered the nearest densely populated center.
The Board ruled that Route 1A l.
to the east of the site serves as the real boundary of the populated area.
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Because the nearest approach of Route 1A is 2.68 km (1.67 mi) from the Seabrook site, the population center distance is at least one and one-third times the LPZ, as required by 10 CFR 100.
The largest city within 80 km (50 mi) is Boston, Massachusetts, with a 1980 population of about 562,000 persons.
It is about 65 km (40 mi) south-southwest of Seabrook.
The projected popula-tion density within 48 km (30 mi) of the site in 1983 is a maximum of about (530 persons per mi2) at about 3.2 km (2 mi) from the 2
1373 persons per km
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plant. The projected population density within 48 km (30 mi) in the year 2025 l
1s ap==r-tad to reach a maximum at about 3.2 km and is projected to be about j
297personperkm (]50personspermi2).
2 The safety evaluation of the Seabrook site has also included a review of potential external hazards (activities offsite that might adversely affect the operation of the plant and cause an accident).
This review encompassed nearby industrial, transportation, and military facilities that might create explosive, missile, toxic gas, or similar hazards. The risk to the Seabrook facility from such hazards has been found to be negligibly small.
A more detailed discussion of the compliance with the Commission's siting criteria and the consideration of external hazards are in the SER.
(3) Emergency Preparedness The Emergency Preparedness Plan for the station has been submitted to the NRC and is undergoing review.
The state and local plans for the areas around the i
site have not been submitted to FEMA for review.
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In accordance with the provisions of 10 CFR 50.47, effective November'3, 1980, no operating license will be issued to a nuclear facility appli..nt unless a finding is made by the NRC that the state of onsite and offsite emergency pre-paredness provides reasonable assurance that adequate protective measures can and will be taken in the event of a radiological emergency.
Among the stan-dards that must be met by these plans are provisions for two Emergency Planning Zones (EPZs).
A plume exposure pathway EPZ of about 16 km (10 mi) in radius and an ingestion exposure pathway EPZ of about 80 km (50 mi) in radius are I
required.
Other standards include appropriate ranges of protective actions for each of these zones, provisions for dissemination to the public of basis
,l emergency planning information, provisions for rapid notification of the pub-l lic during a serious reactor emergency, and methods, systems, and equipment
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- Staf f's analysis of accident consequences presented here accounts for the transient population a,s a weighted average addition to the normal i
population.
i Seabrook DES 5-44 I
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./. ! N-crossing the site to the northeast of both reactor units. This location of the divide would mean that the flow of anf contaminated groundwater from the reactors would be in the direction of the marsh to the south.
Groundwater could enter the marsh soils underground at the interface of the soil and bedrock, or it could seep from places where bedrock is exposed.
According to maps (FSAR Figures 28.12 and 25.14) showing bedrock and surface topography of the site, l
bedrock is only a few feet below the marsh surface to the south of the site, and may be exposed along the site boundary near the seawalls and riprapped banks.
The swamp to the south adjacent to the site is flat and seve'ral feet above normal high tide.
Frequency plots of tides along the coast (FSAR Figure 2.4-15), which are typical of Hampton Harbor, indicate that flooding of the marshland adjacent to the site would be common.
Tides exceeding 6 or 7 feet above mean sea level (MSL) datum, which would bring water within a few feet of the site boundary, have recurrence intervals of less than 2 years. The staff has chosen a represent-ative groundwater pathway of 360 feet in length, which is the distance between the center of the Unit 2 containment building and the 6-foot MSL contour.
Contaminated groundwater is presumed to migrate to the marsh through fractured bedrock and to enter surface water in the marsh at times when it is submerged.
The groundwater level on site is conservatively chosen to be at plant grade,-
20 fut MSL.
The permeability of the fractured bedrock is taken as the average f
measured value of 4 gpd/ft.
The effective porosity of the bedrock is taken 2
as 0.01, which is typical of water-bearing fractured crystalline rock (NUREG/
CR-0912).
The travel time for groundwater to migrate to the marsh has been predicted to be about 170 days. Movement of much of the radioactivity would be slowed, I
however, by sorption.
Retardation coefficients of the two potentially most significant radionuclides, Cs-137 and Sr-90, are very difficult to estimate.
f A small number of in situ measurements in fractured granite indicate a retarda j
tion factor of between 4 and 6 for Sr-90 (ibid).
Retardation factors for Cs-137 have not been measured in these experiments, but they are usually much greater than those for Sr-90.
For the present example, retardation factors of 5 and 50 have been chosen for Sr-90 and Cs-137, respectively.
For these conditions, 94% of the Sr-90 and 58% of the Cs-137 would eventually enter the marsh.
This compares to 87% of the Sr-90 and 31% of the Cs-137 escaping the groundwater pathway in the LPGS example.
Radioactive groundwater seeping in to the marsh would~ encounter marsh deposits of silt and and clay and.would'be adsorbed; the movement of most radionuclides would be slowed to a certain extent.
Retardation factors for Sr and Cs for most soils in salt or brackish water are l
considerably smaller than the corresponding values in fresh water.
Because the marsh is frequently inundated with salt water, it may hold relatively little of the radioactivity. The staff has conservatively assumed that any Cs-137 or Sr-90 escaping to the marsh would be subsequently carried to Hampton Harbor and to the Gulf of Maine by tidal flushing.
Although Hampton Harbor--and its marsh complex--is technically an estuary, it is relatively small in volume and area, and has a large tidal prism (volume l
difference between high and low tide).
An estimated 88% of the volume of Hampton Harbor and the marsh is exchanged with the Gulf of Maine each 12.4-hour tidal cycle; this exchange would quickly and thoroughly flush dissolved pollutants.
The estuary site chosen in the LPGS study had a much slower rate of flushing (on the order of months), and also had much higher usage (such as fisheries and shorelines) than the Seabrook site.
Therefore, the LPGS-Seabrook comparison will consider the Seabrook site as an oceanside land-based plant.
Seabrook DES 5-62 J
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