ML20128B486
| ML20128B486 | |
| Person / Time | |
|---|---|
| Site: | Monticello  |
| Issue date: | 04/21/1966 |
| From: | US ATOMIC ENERGY COMMISSION (AEC) |
| To: | |
| References | |
| NUDOCS 9212030670 | |
| Download: ML20128B486 (6) | |
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- 11. S. ATOHIC EN3RGY COMMISSION _
DIVISION OF REACTOR LICENSINO ggPORT TO ADVISORY COMMITTEE ON REACTOR SAFEGUARDS IN Tile MATTER OF NORT11ERN STATES POWER COMPANY PRELIMINARY SITE EVALUATION - PROJECT NO. 416 0
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1 Note by the Director. Division of Reactor Licensing The attached report has been prepared by the Division of Reactor Licensing for consideration by the Advisory Comnittee on Reactor Safeguards at its May 1966 meeting.
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OFFHCHAL USE LlhJ Introduction By letter dated March 17, 1966, the Northern States Power Company requested an informal safety review of a proposed reactor site near Monticello, Minnesota.
The nearest population center, St. Cloud, Minnesota, is 22 miles from the site and suburbs of Minneapolis are about 30 miles from the site. The staf f has conducted an evaluation to determine the suitability of the site for a General Electric boiling water reactor with an ultimate capacity of about 1674 MWt.
Site Description The site is located three miles northu" -f the Village of Monticello, Minnesota (population 1,500) on the Misst -i g k a 4 ' site is owned by_
Northern States Power and contains about 13I. c ;- e.d isnd on both sides of the river including the islands in the river. The utilit'y presently piens to locate the reactor plant on the southwest bank of the river and a minimum exclusion distance of about 1800 f eet (to the south) would be provided. The distance to the nearest residence is about 3000 feet. The population density distribution indicates 23 people within 1 mile, 3940 people within 5 miles and 9700 people within 10 miles, distributed such that the largest population out to 10 miles in one of the 16 directional sectora is about 3 times larger than the average sector.
Based on the information submitted the low population distance appears to be at least 15 miles and the nearest population center (St. Cloud, Minnesota, population 33,P00) is about 22 miles from the site.
As indicated in the report furnished by NSP the site is in a Intitude that is subject to severe vinter weather and is also subject to tornado activity. NSP in presently preparing a general climatological sumary of the area based on data from the U. S. Weather Bureau stations at St. Cloud and Minneapolis, Minnesota.
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e OFFHCHAL USE 0 li They also plan to initiate an on site meteorological program. The design problems associated with the weather conditions are recognized by NSP and will be taken into consideration during design of the plant. We do not anticipate any unusual problems in this regard.
f The applicant has discussed the geology, hydrology, and seismology of the site in the application. Although the staff has not obtained written comments from the U. S. Geological Survey or the U. S. Coast and Geodetic Survey, on the basis of informal discussions with these consultants, we believe that no unusual problems exist in these areas. Flooding of the facility by the Mississippi River should ,
not be a problem since the highest recorded flood level at the site is 916 feet above MSL and the elevation of the land is about 920 feet at the proposed site of the reactor.
The Monticello site was visited by members of the staf f on April 13, 1966.
Several site-related items were brought out in our discussion with Northern States Power representatives.
(1) The site boundaries are not fully indicated in Figure 2 of the report.
Northern States Power owns land immediately along the river for about 1 mile in both directions and will have ownership of the wooded islands in the river.
(2) The applicant was asked whether water movement from the river during flood stage could carry contamination to shallow wells in the vicinity.
It was stated that this would be looked into, although no problem was visualized because of the distance of these wells from the river.
(3) Since adequate cooling water will not be available during certain months of the year due to the low level of the river, cooling towers will be provided. The towers will be deatgned to carry 100% of the reactor cooling load.
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Site Annivsts An analysis was performed for a 1674 MWt General Electric BWR with a pressure suppression containment to illustrate that the potential maximum doses will be within Part 100 guidelines. Doses were calculated for the proposed minimum exclusion distance of 0.34 mile and a low population distance of 15 miles.
For a contained loss of coolant accident the fission product release fractions specified in TID-14844 were assumed. The fission products were assumed to leak f rom the pressure-suppression containment directly to the environment through a halogen filtration system and the stack at 0.7% per day. A halogen filter effi-ciency of 90% was assuned. The Pasquill diffusion envelope (CRO-545) was used with a 1 m/sec. vind speed and 100 meter stack to maximize dose with distance. Results are given in Table 1.
Two cases were considered for the steam line break accident outside of con-tainments (1) All fission products entrained in one-eighth (60,000 lbs) of the primary system vater were released at ground level. The fission product '
inventory was ba ,ed on Dresden I measurements extrapolated to an operational stack release rate of 0.5 curies /sec. The steam line flow restrictors were assumed to limit the flow during the 11 second valve closure time.
(2) If gap fission products from 40 fuel rods were released at ground level after 50% halogen plateout, the thyroid dose at the site boundary would be 300 rem. However, in our opinion the fuel can be designed to give assurance that only a snail number cf random pin f ailures .ould be expected to occur as a result of this accident.
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TID 14844 (Pasquill Type F) meteorological conditions with a wind speed of 1 m/sec.
were assumed in the steam line break accident.
TABLE 1 Potential Off-Site Doses (rem)
Two Hour Dose Course of Accident 0.34 Miles 15 Miles Accident Thyroid Whole Body Thyroid Whole Body Loss of Coolant 11 41 100 $
Steam Line Break (1) 1/F primary system 35 41 41 41 (2) 1/8 primary system plus gap fission products from 40 fuel rods 300 14 1 41 The doses f or the coolant loss accident assume a 907. halogen filter ef ficiency and release from a_100 meter stack. Without the halogen filtration system and the stack the guideline doses given in Part 100 would be exceeded by a. f actor of approxi-mately 36 at the exclusion distance and a f actor of 7 at the low population distance.
The doses (in the above table) from the steam line break accident would be reduced by a f actor of 10 if a plume rise of 100 feet is assumed and further reduced if credit is given for the wake of the turbine building.
Reactor Considerations The following is presented for the general information of the Comnittee on the unique features of the proposed reactor facility.-
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(1) The efficiency implied by the net electric and thermal power quotations in the application is lover than that in similar recently reviewed reactors. This is probably due to an allowance for cooling tcver fans although the applicant stated that natural draft towers were being considered.
(2) Since the Mississippi River is not navigable above Minneapolis, the j l
reactor vessel vill probably be field-fabricated. The applicant was asked to be prepared to discuss quality control during field-fabri-cation as a matter of general interest. (General Electric is pre-paring a special report on this problem and vill present it in connection with a seminar prior to the filing of an application).
(3) The reactor core isolation cooling (RCIC) system proposed for the reactor has not yet been reviewed by DRL. (See report on the RCIC dated October 15, 1965, which was provided in connection with a GE seminar held in Bethesda on October 21, 1965).
Conclusion Ve believe the Monticello site is suitable from a population standpoint for a General Electric boiling water reactor of the type described in the submittal assuming the usual engineered safeguards for this type of plant are provided. As noted previously, a detailed evaluation of the meteorological, geological, hydro-logical and seismological characteristics of the site has not been made. However, no unusual problems that cannot be handled by conventional design practices are anticipated.
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