ML19319B888

Requests That Util Evaluate Effects of Increased Fission Gas Releases on Safety Analysis Per Specified Schedule. Discussion of Underpredicted High Burnup Gas Releases Encl

ML19319B888
Person / Time
Site:	Davis Besse
Issue date:	03/29/1977
From:	Stolz J Office of Nuclear Reactor Regulation
To:	Roe L TOLEDO EDISON CO.
References
NUDOCS 8001290612
Download: ML19319B888 (7)

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ELD flRC POR IE (3) b I

Local PDR R Reid MAR C 51977 LWR 1 File C. L! son A

D. B. Vassallo D. Eisenhut

_h" F. J. Milliams K. Goller

, j, J. Stolz ACRS (16)

L. Engle J. ' tiller Locket 'lo. 50-346 E. Hylton V. Stello R. Heineman.

D. Ross Toledo Edison Connany J. Knight, SS ATT!i: ifr. Lowell E. Roe R. Tedesco Vice Presidant, Facilities H. Denton Development V. A. l'oore Edison Plaza R. H. Vollmer 300 l?adison Avenue it. L. Ernst Toledo, Ohio 43c52 W. P. Gammill Gentlehen:

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J. R. Buchanan, MSIC T. B. Abernathy, TIC SUSJECT: FISSIGH GAS RELEASES FRC?i FUEL PELLETS (DAVIS BESSE i4UCLEAR PCWER STATIC.'l !!ilIT NO.1)

The :RC staff has recently obtained information which indicates that fission gas releases fron fuel pellets with high burnup may be under-

redicted by the current industry s

wdels for fission gas release.

As a result, actual end-of-life fuel rod pressur9 ray be hicer than that which was considered in the safety analysis for your facility.

Although this situation does not lead as to suspect that fuel design limits have been or are currently being exceeded at your facility, the potential r.,ay exist for such an occurrence in the future as higher fuel burnups ara reached. Consequently, you are requected to evaluate the effects of increased fission gas releases on the safety analysis for your facility in accordance with the scSedula i

specified below.

If the estimated date on which any fuel rod in your facility will reach a local exposure (burnup) of 20,000 Twatt-days oer retric ton of Uranium (!NU/tU) is sooner than June 1,1977, provide the following infomation within 30 days of receipt of this letter.

(if this estimated date is later than June 1,1977, your response may be submitted within 90 days of receipt of this letter.)

fuel rod in your facility vill The estimated date on which any) of 20,000 !!egawatt-days per mtric a.

reach a local exposure (burnup ton of Uraniun (iND/tU).

b.

Using the correction technique described in the attached crclosure,

nodify the fission gas release rodel in the thermal perfor,ance code for the fuel in your facility and calculate the fission gas gu ;

release, fuel rod pressure, fuel temperature, etc. for burnuns un to and including the target peak-rod burnup, Provide a comparison p

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i977, Toledo Edison Company the results of your calculations with those obtained using the uncorrected fission qas release model, c.

Descr',be the imoact (if any) of larger fission cas releases en the LOCA analysis and other safety analyses for your facility, d.

If it.ternal fuel rod pressures, as calculated using the above-mentictmo fission gas release correction, are predicted to exceed the nominal systen nressure for your facility, provide the date that this is anticipated to occur and discuss the implications of operating under both norml and accident conditions with fuel cladding tensile stresses.

We ha'/e advised all U. S. Fuel nanufacturers by separate correspondence that this information request is beinq sent to licensees of operatina power reactorp or to licensees of plants 5thich are presently under CL review and estimated to receive an CL license in the near future.

In our letter to the fuel manufacturers, we hava indicated that houndinq calculations for approoriate plant aroupings would be acceptable.

This request for generic inferration was approved by CV' undar a blanket clearance number S-180225 (R0072); this clearance expires July 31, 1977. Three signed originals and 40 copics of your response will be required.

Sir:cerely, orter.31 si,.,p,;7 Ji m V.Stalz John F. Stolz, Chief Light L'ater ;'eac tors Srar.ch o I

livision of Project."aragement

Enclosure:

Burnup-Jecendent Ccerection fcr Fission Oas. Release "ocels cc u/ enclosure:

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3 Toledo Edison Co:npany 3-cc: Mr. Dcnald H. Hauser, Esq.

The Cleveland Electric Illuminating Company P. O. Box 5000 Cleveland, Ohio 44131 Gerald Charnoff, Esq.

Shaw, Pittaan. Potts and Trowbridge 1300 M Street,ii. !!.

!!ashington, D. C.

20036 Leslie Henry. Esq.

Fuller. Seney, Henry and Hodge 3JJ.!adiscn Avenue Toledo, Ohio 4360d m9 0

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r' Recent ANS standards activities (,1-2) It ad us to believe that high i

We burnup gas releases are underpredicted by current LWR industry nedels.

have previously (,1) looked for a turnup dependence and found r.cnc for LWR:

in the burnup range fec= 400 to 13,300 mwd /tu. Thus, we incorrectly pre-that 'the strong burnup dependence exhibited by LMF3R data (f) was not su: :

c'

'ative of LWR fuels curing their shorter burnup lifetines.

Ne w.i.ch burnup UD2 data centlened by Westin3 house 0 the ANS group (1) and discussed with the TRO (1) shcw, hcwever, that the sharp release increase seen in LMF3R data occurs also in LWR fuels. Therefore, in the absence Of a conplete analysis of high turnup LWR UOt data, we wl:1 assu..e that the b :-;up dependence is the same in LWR and LMFER cxiv.e fuels. This assu ; tion,.: wever, will te applied only in the hign burnup region above 20,000 mwd / U since th.

1 current industry sede13 have been checked with the data case (1) rangin; ::

ic,300 !!Wd/tU.

i The following correction has been derive to give in -increased relsace fraction F'(Su,T) as a fanction of turnup and the unecerected release i

c predictlen F(T). Burnup Su is the local burnup in negawatt-days per ne ric 4

l ton of uranium (mwd /-U), and T, which is not an explicit variable in the 3

correction, is tenperature.

i (1 - exp[-0.436 x 1v '(Bu-20000) )

-( ) +.1

(.)]

- (2u,4)

i L c i

=

c -

(1 + [0.665/F(T)]exp[-1.107 x *C '(3u-20000)?:

1 4

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Figure 1 shows schematically how this correction would be r.pplied to the GAPCCN gas release codel, which is independent of burnup.

In the event an existing =cdel contains a burnup dependence, F(!) would be the predicted release fraction under the te perature conditions of interest, but with the burnup variable set equal to 20,000 mwd /tU.

Equation 1 is a replicatien of the Dutt and Saker (1) LMFER ccrrela-tion, which is an redated version of the correlation in Ref. 5 Equatien 1 was derived by assuming a convenient functier.a1 for: depending on F(T) and Bu and fittir.s it to the Dutt and Eaker curves using a non-linear regressica 4

procedure. No conservatis: has been intentionally added.

Figure 2 shcas how clcsely Eq. 1 re roduces the Outt a.n: Saker curves.

i.

1.e_ fo r n - e_s-1.

R. C. Meyer (N;0), tenorandue o ?. S. Check, "Suneary of Meeting cf ANS-5.4 Workins Occup on Fuel Flenu Osc Activity," February 25, 1975.

2.

R. O. Meyer (NFC), encranda: to ?. S. Cneck, "Su::ary of ANS-5.1

(;ecay Heat) and ANS-5.4 (Fiss'.cn cas Release) Activities," June 22, 19 5.

3 R. C. Meyer (NRO), retorandum to P. S. Check, "Su==ary of ANS-5.4 Meeting On Fissien Gas Release," October 6, 1976.

4 C. E. Eeyer and C. R. Hann, " Prediction cf Fission Gas Reicace fre

'J C Fuel," Sattelle repert, SNWL-1575, Ncve:ber 1974 5

D. S. Outt, D. C. Sullington, R. B. E;ker, and L. A. Pember, J

" A Correlated Fissica Gas Release Mode.1 Ter Fast Reactor Fuels," Trans.

Am. Nucl. Sec. 11, 193 (1972).

4 6.

R. O. Meyer (NFC), =emorandum to ?. S. Check, "Suenary of Meeting witn Westinchcuse en Fuel Rod Pressures," September 22, 1976.

7 D. S. tutt and R. 3. Baker, "Siex:

A correlated Code for the Fredictit-of Liquid ets1 Fast Greeder Reactor (LMF3R) Fuel Thornal Performance,"

'r.'estin hcuse Hanfo-d report, HEOL-TMI 7"-55, June 1975 i

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