ML19312C917
| ML19312C917 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 05/06/1975 |
| From: | Long F NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | Thornburg H NRC OFFICE OF INSPECTION & ENFORCEMENT (IE) |
| Shared Package | |
| ML19312C914 | List: |
| References | |
| NUDOCS 8001140579 | |
| Download: ML19312C917 (7) | |
Text
,
S uraitto srAits fJUCLEAR REGULATORY COf."T.11SSIOfJ DlHECToR ATE oF REGUL AToRY ol'ERATioNS REGlorJ f t 230 PE ACItTH EE ST R EET. N. W.
SulTE $18 ATLANTA.GEOHGIA 30303 May 6, 1975 H. D. Thornburg, Chief, Field Support and Enforcement Branch Office of Inspection and Enforcement, Neadquarters THRU:
N. C. Moseley, Director, Office of Inspection and Enforcement, 7(!(
Region II j
DUKE POUER COMPANY, OCONEE 2, 3, CORE LIFT FLOW CONSIDERATIONS The cost recent B&U licensee analysis shows that Unit 2 fuel lifting would occur at 111.4% of design flow at end of core life which is approximately 0.5% less than the present calculated lift flow rate of 111.9%.
The existing Unit 2 flow is believed to be 111.5% of design, although determination of this value is questionable due to inaccuracies in instrumentation used.
The licensee has taken the position that this flow condition does not constitute an unreviewed safety question.
Since we cannot make a final conclusion regarding this estter, we believe a transfer of lead responsibility to Licensing is the appropriate action.
The licensee is planning a series of tests in 3 and 4 pump configurations in an attempt to physically detect any vertical displaccuent of fuel.
It is our opinion that 4 pump operation should continue beyond these tests only after the flow question has been totally resolved to the satisfaction of Licensing.
Although there appears to be less concern regarding the flow conditions on Unit 3, we believe the question should be resolved simultaneously on both units.
It is therefore requested that the lead responsibility for the core lift question be transferred to Licensing.
k F. J. Long, Chief' 4
Facilities Operations Eranch I
cc:
T. N. Epps W. C. Seidle t
K. V. Seyfrit e
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The b:cin for doin; thin analvois in that flow han bec.a t:m.te:S at greater than 111% of de r:i gn flov (131.37.10's Ib/br) which is asmmed nuf fielent to lift oppror.i-unt ely 10 centrally-lecated f uel anserblica containing C;"-
en uir, of t hese
{ ',,ssenb11e ; during flov reducing transiente could 'pot
').1! Ak / k t o the syrtem an the cont rol rod insertion is chifted.
Since the
.m.enblies vould be expected to rescat during loss--of-coolant flov '{LCCF)
{/condi tions,, nu3rlynes were deemed necessary-for the lepump constdova.cnd locked c
!j eotot' transients only.
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- Analysis Asr.umptions The basic assuu:ption is that the reactor is operating at 102% power, 111% flow when one of the f olloving transients occurs:
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44 ump Coastdevn b.
Locked Rotor
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- It is further nostmed that, the LOCF allows the assemblics previously lifted to y
0 settic bach dovn adding 0.11 Ak/k reactivity.
For conservatism, this reactivity g
- van added instantaneously at the onset of the transient.
All other assurptions
. 's and data are consintent with the accident analysis presented in the Oconee PSAR [
nd Ocone.e fuel densification report.
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V Ecsults 4
f I
The accident analysis results for the pump coas tdovn and locked rotor are showoj t in Figures 1 and 2, respectively.
The two transients were allowed to trip the ii
-- ren et er on the flug/ flow function, alt. hough it is likely the 4-pua.p constdown
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vould initially trip on pump monitors.
t1Ie'~ Ydn~gis~t d'e'lly IIice u'stil rod inser Ilowever, with the flux-f1'ov trip having i}
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~~M'44p~u::rp analycis is caam=rvartve. -
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The results of these accident analyses were then used for D;tta calculations based on hot channp1 condfti'ons and ac w l
unting for system errors.
In addition, g.,t.A:nsified fuel p,arcoa ters were also used.
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T' 63; h minimum DNBR.(or c;nxiono clad surface tempe rature if f".7oh, r "M ia given in 'Inble 1.
For each accident analyztd, thc' DNDhe result is given for ing occurs)
(1) the case when lift occurs and (2) the base case of design"I'. low and no li f e.
Although the accident analysis shows higher peak neutron powers in the Oconee Fuel Densification Report, Table 1 clearly it.Acates the DRER than presented
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condition is less severe for the case where lif t 1
occurs.
This-isdueprincipally]
to the f'act that, vi th 1111' of design flow prer.cnt, the DNB ratio.at the transient the onset of h is auch higher and compensates for the higher peak neutron power b
Teached during the transient.
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' Based on the above information, and bearing in eind that the increased flow
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_.. a.icaf.Li. coolly inc reases the in.it.lal UNUR cargin, we can support the..rcsponse
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- to Part 2 of Attachment 1 aa follows
No - Increaned flow rate would not have any action cauning increased 2.a.
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probability of occurrence of any accident previously cualyzed d
in the Oconce FSAR.
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No - As supported by this analysis, increased flow ratd LUuld benefit previous analysis by increasing the initial DNBR r.;r--In.
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No - This analynin has shown that although th*
initiatir-f,v;chenins for the trannients is different than that presented. fin 7the FSAR, the consequences are less nevere and therefore, bocaded by.the nnalynfo in Chapter 14.
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the.,p,rphability@of safety
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No - Increased flow rate yould not. increase t
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equipment malfunction.
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No - n e consequences of safety equipment malfunction Iird not increased [
by increased flow rate.
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f.
No - The increased flow rate vould not create ma3 functida of safety related. equipment di.fferent than any evaluated in'the FSAR.
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No - The analysis presented in this memo conclusively abows that the..
safety margins are not reduced and the bases fot* t% Technieni Specificationsarestillvalidunderincreasedf%'/corelift 1
',condi tions.
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TABLE 1
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s Base Case - No Life High Flou - Core Liftoff, MDNBR Transient HDNBR (W-3)
E1x. Clad Temp (6 from Base),
Clad _ Temp (a 4-Pump Constdown 1.53 V // // I M.03 V///M tocked Rotor V////l 1380 F V///l
-45 F
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Reference:
BAW-1388, Rev.1. Oco?. 'e-I Fuel Densification Report, July, 1973.-
- Clad surface temperature calculated in film boiling -redion when DHERdrop{below1.30(W-3).
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- 2., S/pt"lY INAT,1%T10!!
a, Yes,__,,,,Ho,[, WJ 11 the proliabili t y of an accident previour.ly *cvalua te thu F5/JL be luc rt;a::cd 7 6, Yest
_ No
.. Uill t he conseqtiene es of an accident prt 'iously evalua ted in Lbc FS/J1 be Jiicrunt.edi C. YC" No.
- nay the p nu n,ilig f an accident which in dif fer ent than any already evaluat ed in the PSAR be c'rcated?
d, Yes No X-will the probabilit y of a nalfunc t ton.or equipment important to, safety prevjously evalua ted in the l'5AR be increasod?
( Yes no_
Will the co'nccquencer. of a malfunc tion of equipment to safety previously evaluated in the FSAR be increased?
inportant f,Yes No.
_ Pay the possibility of a nalfunction of equipment.
to safety differont impor tant than any aircady evaluated in the FSAR be c rea ted ?
- % Y e s Ho %
U1'11 the tarcin of ::arcey as defined in the haces to Technical Specificalion be reduced?
any If the answer to any n, of the al ave ques tione is " Yea," an unreviewed safety question is involved,
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3 RD:ArWS:
('Ihc reason (s) addi.tional pages if necess. ry.)for the answer to cach of the above must be Attach y
- 44. Atcycit.
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PREPAHf.D BY:
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