Text

Proposed Tech Specs,Providing Guidance on Calculational Methods for Determining Effects of Fuel Densification
	ML20024G592
Person / Time
Site:	Monticello
Issue date:	02/28/1974
From:	; NORTHERN STATES POWER CO.
To:	;
Shared Package
ML20024G589	List: ML20024G588; ML20024G591; ML20024G592;
References
	NUDOCS 9102130441
	Download: ML20024G592 (6)
	v • d • e

i 3.0 LIMITING CONnITIOE FOR OPERATIM 4.0 c'mlT.IttrCE REQUIPE!iENTS 1 T. Rectreulation System Recirculation System I.

1 Except as specified in 3.5.1.2 below, whenever 1. Once per month. when irriat ed fuel is in t;i-irradiated fuel is in the reactor, with reactor I coolant tenperature nreater than 212"F and both reactor with 0

reactor coJiant temperature nrs reactor rect re'ilatfor pumps operatint, the than 212 F and both reactor recirculation pumps operating, the recirculation svnten cre recirculation system cross tie valve interlocks shall be operabic.. tie valve interlocks shall be demonstrated to 3

be operable by verifying that the cros tie

2. The recirculation system cross tie valve inter-valves cannot he opened using the normal cont:

switch.

Iocks may be Inoperable if at least one cross tie valve is maintained fully closed. 2. When a recirculation system cross tie valve interlock is inoperable, the position of at least one fully closed cross tie valve shall J. Average Planar LHCR be recorded daily. j During steady state power operation, the average linear heat generation rate (LHGR) of all the J. Average Planar LHGR rods in any fuel a sembly, as a function of average planar exposure, at any axial location, Daily during power operation, the averate shall not exceed the maximum average planar LHCR planar LHCR shall be checked. ~

l shown in Figure 3.5.1.

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t 3.0 LIMITING CONDIT10?!3 FOR OPERATIO*: 4.0 SURVET T IA!!CE REQJIRPJTl.'TS K. Incal DIGR K. Tecal UIGR t During steady state power operation, the linear Daily during reactor power operation. the heat generation rate (UIGR) of any rod in any local TXR shall be checked.

fuel assembly at any axial location shall not exceed the maximum allowable DIGR ao calculated i l

by the following equation- i U!GR S UIG;l I- OF ,

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max d j P[ max

} LT[

UIGR d = Design U!GR I

= 17.5 kw/f t for 7x7 fuct

, = 13.4 kw/f t for 8x8 fuel i f 1

.' bl max = Maximum power spiking penalty i

= 0.033 for 7x7 fuel

= 0.024 for 8x8 fuel LT = Total core length = 12 ft L = Axial position above bottom core 3.5/4.5 108F REV i

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Bases Continued 3.5:

, J. Average Planar L'tCR This Spacification assures that the peak cladding tmerature following the postulated desis;n basir loss-of-coolant accident will not exceed the 2300"F limit specified in the Interim Acceptance Crit ria (LAC) issued in June 1971 coneidering the postulated effects of fuel pellet densification.

The peak cladding temperature following a postulatei f oss-of-coolant accident is primarily a functinn of the average heat generation rate of all the rods of a fuel assembly at any axial location and is only dependent secondarily on the rod to rod power distribution within an sasembly. Since expected local variations in power distribution within a fuel assembly affect the calculated peak clad temper-ature by less than + 200 F relative to the peak temperature for a typical fuel design, t'te limit on the average IInear heat generstion rate is sufficient- to assure that calculated temperatures are below the IAC 11mit.

The maximum average planar UIGR curves shown in Figure 3.5.1 were calculated for the various Morticello fuel- types in. the manner discussed in Section 4.3 of Gener'al Electric topical report. "GEGAP-III: A Model for the Prediction of Pellet-Cladding Thermal Conductance in BW Fuel Rods". NEDO-20181. Revision 1, November 1973. These cur.res show the composite limitation based on the design U1GR of the fuel and the peak cladding temperature in the event of a IDCA. Calculations based on the AEC 'hodified CE Model for Fuel Densification" attached to a December 5,1973 letter from D J Skovhoir (USAEC) to L 0 Mayer (T4P).

The possible effects of fuel pellet densification were: (1) creep collapse of the caldding due to axial gap formation; (2) increase in the UIGR because of pellet column shortening; (3) power spikes due to exial gap formation; and (4) changes in stored energy due to increased radial gap size. Cal-culations show that clad collapse is conservatively predicted not to occur currently or prior to September 1974. Therefore, clad- collapse is not considered in the analyr.cs. Since axial thermal expansion of the fuel pellets is greater than axial shrinkage due to densification, the analyses of peak clad temperature do not consider any change in UIGR due to pellet column shortening. Although.

the formation of axial gaps might produce a local power spike at one location on any one rod in a l fuel assembly, the increase in local power density would-be less than 27. at the axial midplane. S irc e small local variations in power distribution have a small effect on peak clad temperature, power spikes l were not considered in the analysis of loss-of-coolant accidents. Changes in radial gap size affect 3.5 BASES II 3 #-

RE"

. . _ _ _ . _._ _ _ _ _ .__ _= _ _ _ _ _ _ _ _ _ _ _ _ _ . _ . . _ _ _ ___ _ _ _ _.__.__ _ _

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Bases continued 3.5:

the peak clad temperature by their effect on pellet clad thermal conductance and f*rel pellet stored ;

energy. The pellet-clad thermal conductance ownmed for each rod is dependent on the steady st ete operating linear heat generation rate and gap sinc. As discussed in NEDO-20181, Revision 1, the or l size was calculated with the assumption that he pellet densified from its rw asured value to 9".x,

of theoretical density.

The curves used to deternine pellet-clad thermal conductance as a function of linear heat gener, tion !

are based on experinental data and pradict with a 95L conf 1 der ce that 907. of the population excaed ;

the predictions.

i K. Incal UICR i

Ihis Specification assures that the linear heat generation rate in any rod is less than the design Linear heat generation even if fuel pellet densification is postulated. The power spike penalt:- '

specified is based on the analysis reported 1.n IEDO-20181, Revision 1, and assumes a linearly ,

increasing variation in axial gaps between core bottom and top, and assures with a 937. confidence, j that no more than one fuel rod exceeds the design linear heat generation rate due to power spiking. j f

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i 3.5 BASES 113B REY i

AEC DISTP ' TION TOR PART 50 DocrET MATERV

? 1724 (TDiPORARY PORM) CONTROL NO:

PILE:

pry : DATE CT DOC DATE REC'D

.ortliern htates ) we r Connanv LTR l'.D:0 Kl'T OIlu.R

!!inneapoli s , '!! n t, . 55401 Mr. L.O. !'e r r 2-28-74 3-4-74 X TO: ORIG CC OTIER SENT AEC PDR XXX 1.F . O' Leary 3 signed SENT LOCAL PDR XXX

~

CLASS UNCLASS PROP IliTO INPUT NO C)S REC'D DOCKET I;0:

XXX XXX 40 50-263 DESCRIi' TION : ENCLbURES:

Lt r t rans the f ollowing. . .propnacd channen to PROPOSED C}lANGES to tech specs, notarized tech apeen..... 2-28-74 (40 cys encl rec'd)

PLANT NMm : enticen, ' ACKNOWLEDGED FOR ACTION /INFORMATION 3-4-74~ JU EUTLER(L) SCIT4E!;CER(L) /ZIC'M;N(L) REGAN(E)

W/ Copict W/ Copier W/7 Copics CLARK (L) S~OLZ(L) DICKER (E)

W/ Copico DO NOT REUOVE W/ Copict W/ Copice W/ Copict W/ Copies GOLLER(L) VASSALLO(L) KNIGHION(E)

W/ Copics W/ Copics W/ Copics W/ Copies KNIEL(L) SCED:EL(L) YOUNGELOOD(E)

W/ Copier W/ Copics W/ Copics W/ Copics INTERNAL DISTRIEUTION rc rII L TECH REVIE" DD; TON

~A/T It'D vAEC PDR IENDRIE GRI!!ES LIC ASST ggg77ug; c/OGC , ROOM P- 506 A SCIIROEDER GM' iILL / DIGGS (L) S ALE'AN

/l!UNTZING/ STAFF MACCARY PASTNER B. HURT GEARIN (L)

CASE K!;IGHT BAL1J C 00ULEOUR!;E (L) ptggg GIdiBUSSO PAULICKI SPANGLER LEE (L) liCDONALD BOYD SHA0 MAIGRET (L) / DUBE v/ Input

}t00RE (L)(BAR) STELLO ENVIRO SERVICE (L)

DEYOUNG(L)(PWR) HOUSTON MULLER SHEPPARD (E) JNPO

/SKOVHOLT (L) NOVAK DICKER SMITH (L) C. MILES P. COLLINS '

ROSS PHIGHTON TEE 1S (L) B FING DLMISE IPPOLITO YOUNCE; WD WADE (E) A. Cabell

/ItEG OPR TEDESCO REGAN WILLIAMS (E)

PILE & REGION (3) LO';0 PROJECT LDR WILSON (L) liORRIS LAINAS S. REED (L)

STEELE BO;AROYA ilARLESS VOLUEP EXTERNAL DISTRI DUTION l'A

1 - LOCAL PDR__ !!innen tio l i s . ifi g A - DTIE( APE 'M ) (1)(2)'10). NATIONAL L;E'S 1-PDR S A';/LA/NY f A - NSIC(LUCi % N) 1- ASLBP(E/W Bldg,R 529) 1-GERALD LELLCUCHE 1 - ASIB(YORE,SAYRE/ I-W. PENNINGTON, in E-201 GT EROOKHAVEN MAT. LAL WOODARD/"H" ET. 1-CONSULTM;T' S

'16 - CYS ACRS HOLDING 1-AGMED(Ruth Gussran)

NEkHARK/BLUME/AGBABIAN FF- B-12 7. GT.

1-GERALD ULRIFSON...ORNL I-RP . . MULLER. . T- 30 9 GT

_ _ _ _ _ _ - _ _ _ _ _ _ - _ _ _ _ _ _ _ - _ _

ML20024G592

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