ML20128B422
| ML20128B422 | |
| Person / Time | |
|---|---|
| Site: | Monticello  |
| Issue date: | 10/24/1969 |
| From: | Howe P US ATOMIC ENERGY COMMISSION (AEC) |
| To: | Boyd R US ATOMIC ENERGY COMMISSION (AEC) |
| References | |
| NUDOCS 9212030652 | |
| Download: ML20128B422 (15) | |
Text
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t-3 OCT 2 41969 n
R. S.'Boyd, Assistant Director for Reactor Projects, IRL' THRUt S. lavine, Assistant Director for Besctor Technologri DRL
'ACRS REPORT INFtfr - NDRTIERN STATES POWER COWAN - DOCET NO.9
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50-263 - MNITICELID y
our input to the Northern States Power Company - Monti 11e ACRS report is attached.
P. W. Howe, Chief Environmental 6 Radiation RT-791A Safety Technology Branch DRL:ELRSTB:PW!!
Division of Reactor Licensing i
Enclosure:
ACRS Rpt. Input - Monticello ec w/ enclosure:
D. Muller D. Vassallo i
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Form AEC-318 tRev. 9-Sb AECM 0240 u s. sovse==eni,sinnas orrica, soes o-ass-eiv
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NORTHERN STATES POhTR COMPMiY MONTICELLO DOCKET NO. 50-263 2.0 SITE CHARACTERISTICS 2.1 Site Description The Monticello Nuclear Generating plant site contains approximately 1,325 acres owned by Northern States Power Company and is located partially in Sherburne County (on the east bank of the Mirs'ssippi River) and partially in Wrir,ht County (on the weat The site is approximately 22 miles southeast
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bank of the river).
i of St. Cloud (1960 population 33,185) and 30 miles northwest of Minneapolis (1960 population of metropolitan area including St. Paul, approximately 1,400,000).
The nearest residence I
is approximately 2,750 feet from the reactor building.The nearest property boundary is approximately 1,600 feet south of the reactor building whic%
s also the minimum exclusica :ene radius.
The area surrou.. ing the sit.
rural in nature with only a v
few small villages within 15 mi?
of the site.
Based upon 1960 2
t census data, the population witain five miles of the proposed site is approximately 3,900, with approximately 4,800 projected to 1,980.
The 1960 papulation within 5 to 10 miles is approximately 5,800, with 7.100 projected to 1980.
Based upon the population W
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~2 population information which indicates low population density out to distances in excess of one mile (1960 population 23) the applicant considers the low population zone to extend for for a dbtance of one mile. We have reviewed the applicant's analyses and have determined that the Part 100 guidelines for this site, with respect to the exclusion and low population distances (1600 feet and one mile respectively), can be satisfied.
The details of the staff's accident analysis will be discussed in a later section of this report.
2.2 Meteorology The diffusion climatology of Monticello area are typical of that to be expected in the north central United States.
On the average, the diffusion climatology of the north central f
United States is somewhat more favorable than that expected for the rest of the United States due to the rather frequent frontal passages which are accompanied by cloudiness and high winds. The i
applicant has presented one year of meteorological data taken on site (wind speed, wind direction, and vertical temperature lapse rate measured on a 140 foot ;ower) which support these general conclusions. We have revie wed data presented and concluded that it I
does provide an adequate basis upon whic) :!
facility routine effluent release limits can be calculated.
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Tor our accident dose analysis we have used our standard matcorological I
assumptions.
The applicant has presented a range of tetcorological i
j parameters for estimating the potential off site doses with varying meteorological conditions at the site.
The main difference between the applicant's and staff's assua.ptions is that the applicant assumes 15 hours1.736111e-4 days <br />0.00417 hours <br />2.480159e-5 weeks <br />5.7075e-6 months <br /> wind direction persistence while the a
staff assumes four day wind direction persistence, h'ith
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either meteorological codel the calculated accident doses ars
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well below the 10 CFP. 100 guidelino Icycis.
The comments of our reteorological consultant at ESSA have previously been forwarded to the ACRS.
2.3 Hydrology 4
The liquid rad waste system is capabic of maintaining reicases 10 CFR 20 levels on a batch-by-batch basis.
The l'iquid wasto will be discharged into the condenser cooling water downstream of the cooling towers.
The nearest public water intake in the Mississippi River is the St. Paul intale 33 mile river miles from the site, with the Minneapolis intake 37 miles from the site.
In the event of an inadvertent spill Of radioactive contaminants into the Mississippi River, withdrawal of river water can be suspended for a period in excess.of two d:ys for the Minneapolis water system and period in excess of four weeks for the St. Paul system.
Both the staff and the applicant have estimated the effects of routino and accidental releases of lic,uid radioactive effluents frar the facility -
at the St. Paul water intaho.
This will be discussed in detail in the redwaste section of this report.
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4 The plant site natural ;rede IcVel is at an c1cvation of 930 feet MSL.
The worst flood on record was estinated to have reac'c.ed a a
l stage of 916 feet at the si;c.
The applicant has esticated the I
peak stage frem the probabic taxinum flood (P'1F) to be 939.;
i feet MSL.
The original flood protection at the Ci stage was based upon the lot G iod which did not reach plant grade.
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The applicant has paoposed to upgrado the protection of all Class I structures and Class II structures containing Class I equipner.t to withstand the PMF.
The diesel generator building will require placement of a 750 psf load uniformly over its floor (sand bags and/or drums filled with water) to prevent buckling of the floor in the unlikely event of the occurrence of this flood.
Also, some doors or openings would require sand bagging or steel pintes to be pre ected to 930.2 feet MSL. The applicant has concluded
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that the 12 days that are available in case of the occurrence of this flood are adequate to perfor.n these nodifications as needed.
We and our hydrologic consultants at the USGS are presently reviewing the PMF calculations made by the applicant and will report orally at the December ACRS necting of our conclusions relative to the adequacy of the facility flood protecticn.
The USGS consultant comments will be forwarded to the ACRS prior to the December necting, fl
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J Due to the cooling requirements of the plant and taking into account low stret.m flow conditions, cooling towers were included for this plant. The opere. tion of the cooling towers does not present any unusual operating prchlems except a related to release and dilution of liquid radioactive waste.
During minimum flow conditions in t..: Mississippi River, the cooling tower will be operated on a closed cycle with only its blowdown and service discharge going to the condenser discharge canal.
At this time, only a small volume of. water is availabic for the dilution of liquid wastes in the discharge canal.
The applicant is aware of this potential problem, which will occur very infrequently, and he has stated that he is capable of operating under these restrictive conditions and still be capabic of =ceting the requirements set forth in 10 CFR Part 20 on a batch by hatch basis.
2.4 Environmental 'tenitorinc In order to escertain the ipact of nucicar reactor operation at the Monticello site on the environment the applicant will initiate an operational environmental re.diation monitoring progrr.m.
The applicant has conducted a preoperational environmental monitoring program and has provided the staff with one year of environmental monitoring results.
De preoperational monitoring program initiated by the t.pplicant is the basis for the proposed operational program and has provided br.ekground radiation data for the Monticello facility area prior to plant startup.
The operational program
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5-w.- 11 include sampling of airborno particulate matter, sir, soil, ficid vegetation, irrigated food crops, shallow well water, deep well water, raw milk, river (water, bottom sodinent, aquatic vegetation, aquatic bottom organisms, clams, nonmirratory fish),
shallow lake (water, botten sediment, aquatic vegetation and aquatic organists), and precipitation.
The pplicant has delineated the various pathways to man from the environment and described how the proposed monitoring pro;; ram will be c..
'.e of assessing the daily intake of radioactive material from air, water or food by the population at large.
Ecological studies have also been initiated to determine the impact of thermal discharge on the aquatic environment, h'c have reviewed the proposed program and concluded that the program will provide an adequato basis for evaluating the effects of reactor operations on the environment.
The comments of Fish and h'ildlife Service concerning environmental monitoring have been sent to the Committee.
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9.0 nDIDACTIVE blASTE CONTROL 9.1 Routine Licuid asdvarte Peletses Both the applicant and the staff have attcmpted to estint.te u c river water dilution fact 6r that is avail.ble routinely between the Monticello facility discharge canal and the St. Paul water intake.
1 The appliennt estinated the radioactivity concentrations at the St. Paul intake based upon varying condenser and river flow.
The dilution was estimated based upon comnicicly and uniform'.y nixin;;
the condenser discharge flow, with concentrations of 1:-:10~7 uc/cc in the condenser flow, into the, total Mississippi River flow at Monticello, Minnesota, and with no further dilution thereafter.
This dilution assumption is probably reasonable although it 'is not particularly conservative. The range of dilution facters between the site and the intake was from a factor of 1.67 for f
1000 cfs river flow to treater than a factor of 10 for 600n :.nd 400 efs river flows.
No attemnt was nade by the applicant to estimate an annual averap.c dilution factor.
Based upon the probability distribution of flows in the Mississippi River ceasured at a gauging station unstream of the site we calculated the weighted mean dilution factor by uniformly mixing the condenser flow into the total river flow.
Based on the staff's calculations the average dilution fcctor between the 'fonticello site and the St. Paul water intake is 3.5.
Therefore, the river water radioactivity concentration at the St. Paul intake is a factor of 3.5 less th:.n the concentration in the condenser discharge canal during waste discharge operations on :.n avera;:0 annual basis.
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?!PC continuously for a yect the concentr;; ion et the St. P;ul water intake would be itPC/3.5.
The appliennt presently propose that liquid effluent relenses will be below the 10 CFR 20 level on a batch by batch basis, rather than the annual cverage basis which is normally used.
It is unlikely that the cpplicent will release liquid effluer.;a continuously for the whole year, however, with the presently proposed mode of operation the cpplicant could continuously release liquid effluents at the'10 CFR 20 required IcVels which could result in concentrations on an annual averene basis et the St. Paul intake of approximately one third of the 10 CFR 20 values.
The proposed node of operation of the liquid rcdwnste relwases
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does not appear to meet the provisions of 10 CFR 20.106(c).
We htye not as yet discussed this tatter with the applicant.
At the December meeting we will report orally on the results of these discussiors.
The applicant has estimated that.15 ue/see of tritium could be released with liquid radwaste from the facility. With this release rate the concentration of tritium at the condenser discharge outfall would be approximately one millionth of the 10 CFR 20 limit of 3x10' uc/cc.
Even if all of the tritiuta produced by fission (which is the prir.e produccr of tritium), 250 ue/sec, were released to the discherpe canal the concentration of tritium in the canal I
-s-would Le approxinetely one thou:cr.dth of the 10 CFR 20 lir.it.
Therefore, tritium release from from this fr.cility does not cppear to be a probica.
9.2 Accidental Release of Conte?.incted Licuids Tne cpplicant and the staff hcVe evaluated the potential conscouences of releasing all of the radioactive liquids from all the Class II tanks which c.re not contained within Class I structures.
These tanks include the condenst.te storage tanks, waste surge tank, waste sample tcnks, and flost drain tanks.
'lith the release of the expected quantities of radioactivity contained within the A
tanks to the ground and with conservttively rt.pid percolation rate such thct the activity is released to the river in one day.
It was also assured that the relecsed liquids mixed uniformly in the river flow of 1000 cfs.
With these sssunptions
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the concentration of the river water :.t the St. Pcui intaNe would -
be 7x10~7 uc/cc which is greater thcn mixed unidentified limit of 10 CFR 20 however, it is less than the linit that would he appropriate for the expected isotopic mixture.
'A technical specification limit of the quantities of radioactivity that could be contained within these tanks will be set such that the relense of this activity would not result in concentrations at the St. Paul intnte greater than the 10 CFR 20 limits.
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9.3 Routine G secus ilulce.tes The applicant cstinctes that a 2:scous rc'cccc rate of 0.43 c/sce out the pl:nt st:ck would not rceult in off Jito doses in c:: cess of 500 nr/yr. This estincto is bescd upon the pplic;nt';
examin tion of one ye:r of on site retcerslo;ic 1 d:ta.
The st ff h s not yet as its independ:nt c..1ysis of the :pplicant's proposed technical specificatiens fcr routinc 3:scous rele:sc limit for this facility.
Ile vill do so prior to the Occumber ec. ting and will be re dy to di: cuss this nattcr orally with the Cctaittee.
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14.0 ACCIDENT A.\\*ALYSIS a
The folic. ting table presents the results of the c:sff's eclulctions of the potential off site doses for each of the design bcsis ac e '.d ent s.
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POTENTIAL OFF SIT 2 DOSE (REM TfD HCURS AT 490 M COURSE OF ACCIDENT ACCIDENT THYROID W!! OLE BODY Tir *. D 1.'l! OLE BODY t
Control Rod Drop 5
0.14
_1.1 0.27 Refueling 13 0.40 5
0.15 Sten:n line break 20 NEG.
9 NEG.
Loss of Coolant 35 1.4 64 1.3 Attached also is a tabic of the assu.ptions used in ecking these eniculations. -
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TABLE I ASSINPTIONS USED BY THE STAFF !N Tl!E ACCIDENT ANA1,YSIS l
1.
Desirn Basis Accident 1.
TID.14844 release (1000 neble gases, 25t iodines and it solids).-
2.
Design containment Icahage ratc, 0.635t per day for 30 days.
3.
Prirary containment leakage passes through the emergency gas treatment system with charcoal filter efficiency of 90% for iodino.
4.
One hundred and seven meter stack release (no ground release).
5.
Standard man breathing rates.
6.
No correction for plur.c decay or depletion in transit.
7.
Decay during holdup in the containment is accounted for.
8.
"F" condition and U = 1 m/sce for 2 hour2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> dose.
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2.
Stean Line Break 1.
Break occurs at full pover leval, t
2.
Stean line isolation valves close in 10.5 sec;nds.
3.
Total tass of loss = 20,000 lbs of steam and 65,000 lbs of liquid, i
4.
Release is at ground Icyc1 with a building wake effect.
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Release of all iodine and nobic gases from the coolant occurs in two hours.
6.
Coolant activity based on a maxinum technical specification release rate of 0.48 curie /sec with reactor coolant cican-up systen down for 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />.
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Type "F" condition with G = 1 n/sec.
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Refuelinc Accident 1.
Perforation of 111 fuel rods 2.
Gap activity in the rods is released. This is assumed to be 20'. of the noble gases and 10% of the iodine in the rods.
3.
Kater decontanint. tion factor of 10, 4
Peaking factor of 1.5.
5.
The accident occurs 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> after shutdown.
6 Credit 904 iodine recove.1 by charconi.
7.
One hundred and seven reter stack release to the environment.
4.
Rod Drop Accident 1.
The accident occurs 30 minutes after shutdown from full power.
2.
Three hundred and thirty fuel rods are dancged.
3.
Peaking factor of 1.5.
4.
The activity released from the rods is 100% of nobic gases f
and 50t of iodine.
5.
A reduction factor of 10 is allowed for the iodine p:.ssing-through the prinary system wt.tcr.
6.
A plateout factor of 2 is allowed for the turbine and the condenser.
7.
High radiation is sensed in the steamline signaling the ncchanict.1 vacuum pump to stop, and its isolation valves to close.
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All of activity is contained by the turbine and condenser.
9 The leakage rate is n.5t/ day from the condenser, turbine, and turbine building.
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eac to;;l cccide:,: duraticn is 2' ho a n e
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- ine diffusion patte' ' ; 3.
- 3. t.a source with buildin,; wn;;c cafect.
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