ML19317G515
| ML19317G515 | |
| Person / Time | |
|---|---|
| Site: | Crystal River  |
| Issue date: | 02/11/1977 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML19317G509 | List: |
| References | |
| NUDOCS 8003180805 | |
| Download: ML19317G515 (4) | |
Text
'
p
. Enclosure 1
'Recent ANS standards activities Q-l) lead us to believe that high.
=
burnup gas releases.are underpredicted by current LWR industry codels. We have previously-(1) looked for a burnup dependence and found nonc 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.
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New high burnup UO2 data centioned by Westinghouse to the ANS group Q) and discussed with the NRO (1) show, however, that the sharp relcase increase seen.in LMFBR data occurs also in LWR fuels. Therefore, in the absence of a complete analysis of h15h turnup LWR UO: data, we will assune that the b:enup dependence is the same in LWR and LNFSR oxide fuels. This assumption, hcwever, I,
will be applied only in the hi6h burnup region above 20,000' mwd /tU since the current industry models have been checked with the data base Q) ranging to 18,300 mwd /tU.-
The following correction has been derived to give an increased release l fraction F'(Bu,T) as a function of burnup and the uncorrected release prediction F(T). Burnup Bu'is the local burnup in megawatt-days.per ce.ric
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ton of uranien (mwd /tU),. and T, which is not an explicit variable in the e
'3
- correction, is tenperature.
b (1 - exp(-0.436 x 10 "(Be-20000) )
F'(Bu,T)L= F(T) + (1-F(T)]
4 L800818 0 8d 1 =
I t
T r"
~
1
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Figure 1-shows schecatically how this corrt.ction would be applied to the GAPCON gas release model, which'is independent of burnup.
In the event-an existing model contains a burnup dependence, F(T) would be the predicted release fractiori under the temperature conditLons 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 regressica procedure.- No conservatism has been intentionally added. Figure 2 shows how closely Eq. I reproduces the Dut a.nd Baker curves.
Pererences 1.
R. O. Meyerl (HRC), me=orandus to P. S. Check, "Su cary of Meeting cf
- ANS-5 4. Working Group on Fuel Plenu: Gas Activity," February 25, 1975.
2.-
R. O. Meyer '(NRC), nenorandum to P. S. Check, "Su :ary of ANS-5.1 (Decay-Heat)'and ANS-5.4 (Fission Gas Release) Activities," June 22, 197c.
3 Rs 0. Meyer (NRC), me=orandum to P. S. Check, " Summary of ANS-5.4-Heeting on Fission Gas Release," October 6, 1976.
4.
'C.
E. Beyer'and C. R. Hann, " Prediction of Fission Gas Release fre UC
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Fuel," Batte11e report, BNWL-1675. Nove-ber 1974.
- 5.
-D. S. Dutt, D.:C. Bullington, R. B.. Baker, and L. A. Pember, "A Correlated Fission Gas Release Mode.1sfor Fast Reactor Fuels," Trans.
_ Am.?Nu'e1. Soc. 11, 193-(1972).
' 6.
R.10. Meyer (NFC), comorandus to P.. S. Check, " Sum =ary of Meeting witn
' Westinghouse on Fuel' Rod Pressures," September 22,.1976.
- 74. D. S. cutt'and R. B. Baker, "Siex:
A correlated Code for the Predictic.
off Liquid Eetal Fastf Breeder Reactor (L"FBM) Fuel Thental Perforstnce,"
(Westinihouce.Hanford report, HEDL-TME 74-55, June 1975
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