ML17037B647

Letter Concerning a 11/24/1976 Requesting Information Regarding Fission Gas Release Rates from Fuel Pellets with High Burnup and Enclosed Responses to NRC Questions

ML17037B647
Person / Time
Site:	Nine Mile Point
Issue date:	12/29/1976
From:	Rhode G Niagara Mohawk Power Corp
To:	Lear G Office of Nuclear Reactor Regulation
References
Download: ML17037B647 (8)

Text

U.S. NUCLEAR REGULATORY C MISSION T

L NRC FORM 195 I2 78)

~6IRC DISTRIBOTION FoR PART 50 DOCKE MATERIA DOCKET NUMBER 50-220 PILE NUMBER TO:

Mr. Gebrge Lear FROM:

Niagara Mohawk Power Corp.

Syracuse, New York Mr. Gerald K. Rhode DATE OF DOCUMENT 12/29/76 DATE,RECEIVED 1/3/77 PlLETTER SKOR IGINAL

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'DESCRIPTION 0 NOTOR IZE 0 mIUNCLASSIFIED PROP INPUT FORM ENCLOSURE

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NUMBER OF COPIES RECEIVED One'signed Ltr. w/attached....re our ll/24/76 ltr.

....concerning fission gas releases.

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PLANT NAME:

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ERIE SOULEVARO WEST SYRACUSE'I, Y. I3202 Dacke< Fi(e i'II)a(O5 Xo~

,iO gyral December 29, l976 8

Director of Nuclear Reactor Regulation Attn:

Mr. George Lear, Chief Operating Reactors Branch 83 U. S. Nuclear Regulatory Commission Washington, D. C.

20555 Re:

Nine-Mile Point Unit l Docket 'No; 50-220 DPR-63

Dear Mr. Lear:

Your letter of November 24, l976 requested information regarding fission gas release rates from fuel pellets with high burnup..

The attached information is in response to your request.

For Nine Mile Point Unit l, the effects of t'e Nuclear Regulatory Commission fission gas release correction technique are bounded by results presented in a December 22, l976 letter from G. E. Sherwood (General Electric) to D. F. Ross (NRC).

For fuel exposures less than 20,000 megawatt-days per short tori,'eak clad temperature changes are insignificant.

For higher exposurespeak clad temperature increases are less than 85 F.

Si ncerel y, NIAGARA MOHAWK POACHER CORPORATION GE LD K. RHODE Vice Pres'dent - Engineering gR(pz Attachment

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Responses to November

2sl, 1976 Nuclear Rc ulator Commission ucstions Nine llile Point Unit 1

Docket No. 50-220 DPR-63

'gucs tion Provide the estimated date on which any "fuel rod in your facility will reach a local exposure (burnup) of 20,000 hlcgawatt-days per metric ton of Uranium (llND/tU).

~iten lonse Thc core at Nine hlile Point Unit 1 currently contai.ns fuel with peak cxposurcs in excess of 20,000 hlegawatt-days por metric ton of Uranium.

Question Using the correction technique described in thc attached enclosure, modify thc fission gas release modol in the thermal performance code for the fuel in your facility and calculate tlie fission gas release, fuel rod pressure, fuel temperature, etc. for burnups to and including the target peak-rod burnup.

I'rovide a'comparison of the results of your calculations with those obtained using the uncorrectod fission gas release model.

I

~iten.011SC Generic bounding analysis has beon provided by General Electric in rosponse b

of Refcrcncc 1.

Information corresponding to both 7x7 and 8x8 fuel shown for a-BNR/2 is applicable to Nine hlile point Unit 1. The NRC correction technique increases calculated fission gas release, fuel rod internal pressure and fuel t;ripcraturcs for

< x,'osures greater than 20,000 hA~'D/tU.

lLll0 S tt0 ll Describe the impact (if any) of larger fission gas releases on the LOCA analysis and other safety analyses for your facility.

~RCS onse Impact of larger fission gas releases on Nine hlilc i?oint Unit 1 safety analysis is provided in response c of Reference l.

Tho LOCA anal> sis for fuel exposures bolow 20,000 hlli'D/Short Ton arc uneffected At fuel bundle exposures of 30,000 hMD/Short Ton, a conservative uppor bound limit of 85 F peak clad temperature increaso has been calculated.

Tho temperature increases associated with Nine hlile Point Unit 1 are expected to bo significantly

'ower.

Other safety analyses arc relatively insensitive to i.ncreased fission gas release.

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4.

)session If internal fuel rod pressures, as calculated using the above-mentioned fission-gas release correction, 'are predicted to exceed the nominal system, pressure for your facility, provide the date that this is anti-cipated to occur and discuss the implications of operating under both normal and accident conditions isi th fuel cladding tensile stresses.

~Res ense As stated in response d of Reference 1, the internal fuel rod pressures, as calculated using the NRC fission gas release correction, do not exceed the nominal Nine Mile Point Unit 1 system pressures.

REFERENCE 1.

Letter dated December 22, 1976 from. Mr.

G.

G. Sh'envood (General Electric) to Mr. Demvood F.

Ross (Nuclear Regulatory Commission).

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