ML19319A784
| ML19319A784 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 11/29/1976 |
| From: | Schwencer A Office of Nuclear Reactor Regulation |
| To: | Parker W DUKE POWER CO. |
| References | |
| 07722, 7722, NUDOCS 7912120758 | |
| Download: ML19319A784 (6) | |
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,1rn 60-267 Su':c Poece Cemany ATTM: Wr. William O. ParP.cr, Jr.
Vice President Steaa Production Post Office 30x 2170 422 South Churen Street Chirlotta, Nortt Carolina 2.!242 Gentieren:
RE: OCOLEE STATIC *i, l2iITS WS.1, 2. a 3 Tne imC staff has rwently obtainoa infor,ation w'11ch inaicates that fission cas releases from fuel t'ellets wit:1 i inn burnup ray de under-t oredicted by the enrrent inaustry todels for fission ps release.
/s a resul t, actual ene-of-life fuel rod ores ure <1av be b11 er taar' h
that which was consider::: in the safety analysis for your facility.
Althcuch this situation does not lead us to suswet that fuel design limits have been or are currently being exceaded at your facility, the ootential may exist for such an occurrence in the future as hicher fuel ournuos are reached. Consequently, you are recuestoc to evaluate the affects of increased fission cas releases on tha safety analysis for your facility in accordance aita the schedule necified belav.
If tbc estinatad date 09 :hicn any fuel rc:t in your facility <111 reach.* local ex::osure (ternc) of 20,0N "eqauatt-eys.'er metric
- n of Uranf r#1 (W0/t") is :coner than June 1,1977, :ravide t!:e folicwino infor?,ation Mtbin 30 days of receipt of this letter.
(If this estimated cat? 1:: liter than June 1,1977, your resnonsa "3y te sumiitted witnin '.10 days of recebt of thic lo:ter).
.t. The estir:ated date on Wi::5 any fuel red in ynor facility -till ranch a local. ncosura (burnup) of.M,0f.'
'e,mi.t-days rar 70tric ton of Traniun M #.'/tul.
o.
Usi,r: te c^rrection taceniene cescri'm
- in t>e attac:'ea relosure, cr.i fy the fi sit an :as "3issa coel : n ':'c tnomal Oerfor, inca ce? Mr t*a i':e1 i,1 fce:r fac*lih W.s CJICulate D9 fissio7 73% rel 9s?, 6;M r.>
'M W r':, Thel tarparature, etc. for dwaacs *:r. to we includir,- t'io y/
orrICE P summaass >
oavs >
Form ABC MS (Rev. 7 SM ABQt 0240 W u. s. oovsannsamt ruimtema orricas sera.sas.see 7912120 7 6 8 8
NOV - 3195 Duke !)o'ver Conany.
tsraet peak-r# Surrup. Provide a cca n rison of tLe results of your calcul1tions with tiiose, onrain+i usin, the uncerrected fission :ss reless? ?.00el.
1 c.
Describa the ic:'act (if.iny) of br ar fi sina gas reinses on t!'a LOC.) analysi s.in.1 ather safoty analyo.+r, vor ynor heil f ty.
4.
If internal fuel red pressures, as calculaton ushe the 4 cove-entioneo fission nas release ccrrection, are grNicte1 to exceed.the ncninal syste,i pressure for your racility, provit:o the cate tilat titis is anticipatari to acent and discuss the inplications of ocoritino under 50:5 nomal wo accident conditions with fuel cladding tensile stresses.
'le have advised all 11. S. fuel manufacturers by separate core rsoondance that this infor1ation recuest is being sent to licensees of choratine pciver reactors.
In our lotter to the fuel aanuf.1cturers, *:<a nav $
indicated that coundinti calculatiers for apnrocriite clant prourivs trould us accaotaale.
This recu?st for generic infomation was aonr< wen ny :VU undar a blanket clearance nunber 3-W0225 (300/2); this el neance axrf res July 31, 1977.
Three signed originals and 40 cnotes of your response stil be recuired.
Sincerely, CQbal ci;ned by A. Sc6*mncer,1:.tef GU973tf06 la::ctor?. Ar3nch *l Givisico of %er tina Reactors
Enclosure:
DISTRIBUTION Curnun-lerendent Corextion Docket File DEisenhut for Fission Gas Release NRC PDR TBAbernathy
- c tel s LOCAL PDR JRBuchanan a
ORS #1 Reading JGuibert cc v/ enclosure:
VStello w next cane TJCarter SMSheppard ASchwencer 0 Neighbors DELD OI&E(3)
'k4 i ACRS (16)
DOR &RB#1 QOMB#3 bii:0RB#1 DN_hbors:lb. %ibert Mchwencer
= o-11/
16.
l]/N/16 Jlli/76 f
Poem ABC 388 (Rev. 9 55) " BCM 0240 W u. s. eovsman,sav pm,mvine orrices sofe.ase see A
i i
n.
-Recent ANS standards activities (1-J,) lead us to believe that high burnup~ gas releases are underpredicted by current LWR industry models. We
- have previously- (3) looked for a. burnup dependence and found none for LWRs -
in the burnup range from 400 to,18,300 mwd /tU.
Thus, we' incorrectly pre-sumed that the strong burnup dependence exhibited by LMFBR data (1) was not representative of LWR fuels during their shorter burnup lifetimes.
New high burnup UO2 data centioned by Westinghouse to the ANS group (2) and discussed with the NRC (1) show, however, that the sharp release increase seen in'LMFBR data occurs also in LWR fuels. Therefore, in the absence of a complete analysis rf high burnup LWR UO2 data, we will assume that the burnup dependence is the same in LWR and LMFBR oxide fuels. This assumption, however, will be applied only-in the high burnup region above 20,000 mwd /tU since the current industry models have been checked with the data base (4,) ranging to 18,300 mwd /tU.
The :following correction has been derived to give an increased release fraction'F*(Bu,T) as a function of burnup and the uncorrected release prediction F(T). -Burnup Bulis the local burnup in megawatt-days per metric
' ton of1 uranium (mwd /tU), and T, which is not an explicit variable in' the correction,'is temperature.
~ (1 exp[-0.436 x 10 "(Bu-20000)])
'F'(Bu,T) '= F(T)-+ [1-F(T)]
. (1) 2._
. Figure I shows schematically how this correction would be applied to the GAPCON gas release model, which is independenc of burnup. In the event an existing model contains a burnup dependence, F(T) would be the predicted release fraction under the temperature conditions of interest, but with the burnup variable set equal to 20,000 mwd /tU.
Equation 1 is a replication of the Dutt and Baker (1) LMFBR correla-tion, which is an updated version of the correlation in Ref. 5.
Equation 1 was derived by assuming a convenient functional form depending on F(T) and Bu and fitting it to the Dutt and Baker curves using a non-linear regression procedure. No conservatism has been intentionally added.
Figure 2 shows how closely Eq. 1 reproduces the Dutt and Baker curves.
References 1.
R. O. Meyer (NRC), memorandum to P. S. Check, " Summary of Meeting of ANS-5.4 Working Group on Fuel Plenum Gas Activity," February 25, 1976.
2.
R. O. Meyer (NRC), memorandum to P. S. Check, " Summary of ANS-5.1 (Decay Heat) and ANS-5.4 (Fission Gas Release) Activities," June 22, 1976.
3 R. O. Meyer (NRC), memorandum to P. S. Check, " Summary or'ANS-5.4 Meeting on Fission Gas Release," October 6, 1976.
4.
C. E. Beyer and C. R. Hann, ", Prediction of Fission Gas Release from UO Fuel," Battelle report, BNWL-1875, November 1974.
5 D. S. Dutt, D. C. Bullington, R. B. Baker, and L. A. Pember, "A Correlated Fission Gas Release Model for Fast Reactor Fuels," Trans.
Am. Nucl. Soc. J1, 198 (1972).
6.
R.'0. Meyer (NRC), memorandum to P. S. Check, " Summary of Meeting with Westinghous'e on Fuel Rod Pressures," September 22, 1976.
7 D. S. Dutt and R. B. Baker, "Siex: A Correlated Code for the Prediction of Liquid Metal Fsst Breeder Reactor (LMFBR) Fuel Thermal Performance,"
Westinghouse Hanford report, HEDL-TME 74-55, June 1975.
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