ML20011A440
| ML20011A440 | |
| Person / Time | |
|---|---|
| Site: | La Crosse File:Dairyland Power Cooperative icon.png |
| Issue date: | 12/09/1976 |
| From: | Madgett J DAIRYLAND POWER COOPERATIVE |
| To: | Reid R Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML20011A420 | List: |
| References | |
| LAC-4374, NUDOCS 8110130356 | |
| Download: ML20011A440 (7) | |
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54001 December 9, 1976 In reply, please refer to LAC-4374 DOCKET NO. 50-409 Director cf Nuclear Reactor Regulation ATTN:
- r. Robert 11. Reid, Chief Operating Reactors Branch =4 Division of Operating Reactors U.
S.
- uclear Regulatory Cercaission Washington, D.
C.
20555
SUBJECT:
DAIRYL.M:D POWER COOPEPATIVE LA CNSSE CIL!NG tlATER Fl.ACIC 7 (LACi:M )
PROVISIONAL CPE"ATING LICE:.SE :.C.
DP~.-45 J.F PLICATIC:: EC7 /CIE ;DMt.::T TO LICE::SE
Reference:
(1) DTC Letter, LAC-3929, ::adgett to Division of Reactor Licensing,
- RC,
".27 18, 1976.
(2) NRC Letter, Reid to "adgc t,
DPC, Recuest for Additional Information, Enclosures 1 and 2, dated October 29, 1976.
Gentlercr:
We have reciewed your request for additional information (Refer-ence 2) ard are encicsing Supplement :o. 1 to Dairyland Power Cooperative's reload application for Cyclc 5 operation -(Refer-.
ence 1).
the answers to'cinesticnc No. 1 and Included in this supplement are 2 of Enclcsure to. 1 end questiens M' 5,
6, 9,
10, 13, 15, 16, 17, 19 ans 20 of Enclosure !!o. L As we indicated to Ifr. DiBenedetto during cur telephone communication of Notember 9, 1976, cdditional conputer ar.alysis and evaluation is currently being performed to pro-vide further inforrction cn the rcmaining questions, ::cs. 2 through 22, cf Encicsure ::o.
2.
The schedule for completion of the Enclosuro 2 q :cstiens 2, 3,
4, 7,
8, 11, 12, 14, 18, 21 and 22 is projected to be Dcccmber 30, 1976, contir7ent on satisfactory imple-mentation and completion of analytical studies being performed by our consultants.
Jr order ta reet our c.crational ;cheduling necds, your early review, l
eva l ua t i c an:. reply to tnin nutnit tal,. ;16 'e appreciated.
If you
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9110130356 810929 PDR ADOCK 05000409 c
p PDR
L Mr. Robert W.
Reid, Chief December 9, 1976
)
Operating Reactors Branch #4 LAC-4374 I
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have additional questions or comments regarding this submi'ttal, r
please contact us at the earliest possible time.
Very truly yours, DAIRYLAND POWER COOPERATIVE.
~
w Mt, GnTeral Manager l
John 4
"'d JPM: CWA:af cc:
J.
Keppler, Reg. Dir., NRC-DRO III
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.1 SUPPLn1ENT !s0d 4
l Additional Information to Application for Amendment to LACSWR Provisional Operating License No. DPR-45 E: son Type III Fuel Reload Batch XN-1 f
~.., _ _ _
Dairyland Pcwcr Cooperative 2615 East Avenue South La Crcsce, Wisconsin 54632 December 1, 197C s
L? OtOSSE BOILING WATER REACTOR P
NRC QUESTIONS, CNCLOSURE 2 i'
OUESTION 1:
Results of blowdown calculations performed in 1972 using RELAP 3, Hod %,
were used as input to the fuel heatup model.
Verify that thc results ct the 1972 calculations are valid for the new fuel by performing a confirm-atory analysis using the Exxon ncnjet purp blowdown analysis desci.acd in XN-75-f5, Revision 2.
i ANSWER:
t I
A sensitivity study was performed with the approved ENC Fuel Heatup
- odel (FH::) to examine the sensitivity of peak clad temperature (P"T) to likely differences'in heet transfer ccef ficient as would be en-pected between RELAP3h:CD36 and the ENC nonjet pump (NJP) blowdoun model.
The PCT is insensitive to changes in the heat transfer co-efficient auring the initial five seconds of blowdcwn.
The analysis already previded in the "ay 18, 1976 subnittal to show ccmplience with the rcquirements of 10 CFR 50.46 is valid c-d is conservntive.
The fuel heatup analysis provided in the tay 18, 1976 surnittal used the N'.C aperoved ENC NJT-BWR-FD e>:cep t tP.t the het t'Inne heat transfer coef ficient ras taker f ren analysis dore with "ELA?3f :OD3C documented in Reference 1.
M was tynical of that ce n t trn.sfer nodel, the con-vective heat transfer ccefficient was presumec :c Pe zero between time five seconds until the time of rated ccre spra'.
At the time of reach-ing rated spray flov rate (assumed to be 20 seconds) the convective coefficients are based en spray hea* 'ransfer.
l In such. nodel the only hlowdown resu,lts relevance to the fuel t
hetttp analysis are the convective heat tn.nsfer coefTicient-to the time of hot p'ane uncovery and the core average pressure.
The core pressure hisuc;y allows calculation of sprc.y finv rate when dependent on Lack press tc.
This calculation provides only the~ time that rated spray is reached.
The LACB'IR high pressure spra,. syste-Joolant punps are of the positive displacement type.
The pumps vill inject coolant at rated flow at nearly rated reactor pressure.
Therefore, the blcw-down pressure history is not relevant to calculation either'of spray flow rate cr tire cf initiation of spray cooling.
Tests conducted at LACTG R show that it takes less than 10 seconds for tro diesel generators to pick up either ECCC punp and for the ECCS to reach rated spra/ flow rate.
The analysis su;' plied conservatively assumed rated nrra'f at 20 secondn, a substantial conservati m that outweighs any calculated heat transfer history during blowdown.
As core pressure hi", tory is not of concern the onl / other ccnsideration that would encourage reanalysis of blowdown in the convective heat transfer ccefficient t ire-history between break initiation and midplme uncovery, approximately the first five seconds of the trannient.
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A sensitivity study was conducted using the approved ENC NJP-BWR-FHM.
The May 18 submittal used the RELAP?.fMOD36 heat transfe coefficient
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and the sensitivity study used the ctrrently approved NJP-BWR-FHM heat transfer coefficient correlation to the point of core uncovery a.s would be applied to LACBWR fuel.
The resulting heat transfer co-h efficient histories are plotted in the attached figure.
A third
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case was analyzed wherein the RELAP3/MODtG heat transfer coefficient wao assumed to drop to zero at time three seconds.
These cases will lower bound the heat transport during blowdown.
The peak tem.aeresure at five,econds and PCT for the ruee analyses are presented in the following table:
Comparison of Clad Temperatures for ENC NJP-BWR-THM Correlation and RELAP3/!*.0336 Max. Temp.,
- PCT, F,
5 Sec.
F RELAP3/ MOD 3C 1100 2178 ENC FTP-DWR-FEM 1350 2183 RELAP3/ MOD 36 1363 21E5 (3 sec h
- 0) e Within liPely bounding heat transfer conditiens the temperature i
results si.aw that PCT is insensitive to the heat trarsfer coefficient history during blowdown even though there is a substantial clad temp-erature difference at five seconds.
The reasons for this insensitivity are:
The high heat transfer during the first approxicate one second as q
would be calculated by any correlation is acelunte-tc renove prompt fission energy production.
4 i
- Noninal heat transfer as is produced by core flow during plowdown essentially cools only the clad.
Occay energy during the first five seconds in absorbed by the fuel pellet and is stored in the fuel pellet almos t.- independent of surface heat triumport because of the high thermal renistance of urania and j
pellet-to-clad heat transport resistance.
Therefore, even though the clad temperatures are substantially different at timt five secondn, there is nil difforence in PCT an stored enerqy is not sign.ficantly affected during *he firnt few seconds of blowdown.
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In conclusion, the analysis provided in the flay 18, 1976 submittal
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provides adequate conservatisms, no reason exists to produce a pressure history and the PCT is insensitive to assumption of reason-able heat transfer prior to the adiabatic heatup period.
It is, therefore, not necessary to reanalyze LACButt fuel heatup for conform-i ance to 10 CFR 50.46.
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Reference 1:
Technical 1: valuation Adequacy of La Cronse Boilina Water Reactor 1:mergency Core Coolinq Systen,SS-942, t!ay 31, 1972.
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