ML20024B284
| ML20024B284 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 10/05/1977 |
| From: | Meyer G BABCOCK & WILCOX CO. |
| To: | Lauer J BABCOCK & WILCOX CO. |
| References | |
| TASK-03, TASK-3, TASK-GB GPU-2418, NUDOCS 8307080239 | |
| Download: ML20024B284 (2) | |
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THE BABCOCK & WILCOX COMPA!!Y g.,'[,
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POWER GEtiERATIO!! GROUP b' M'. A g i.r.1 ]i 9
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J. A. LAUER, PROJECT MANACEME::T d%3 THI-77-271 jQ, JQ //kg' Froen
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C. A. MEYER. P.U;AGER. T-H E';CINEERI':G UNIT, EXT. 3218 File No.
Cust.
or Ref.
2 TECO - DAVIS SESSE IMIT ONE
.Date Sub).
FUEI. PEF.F0F? U CE - EFFECTS OF DEPRESSUP.IZATION EVENT OCTOBER 5, 1977 i.._....................
During the depressurization event which occurred at Unit One of Davis Eesse on Septa =ber 24, 1977 the RCS pressure decreased to approx 1=ately 900 PSIA for a ti=e period of roughly thirty =inutes.
The RCS temperature during this L
ti=e was in the range of 530 to 540 F.
It has been conservatively esti=ated that the internal pressure of the fuel under these conditions was approxi=ately 1200 psi, therefore,.the fuel cladding was subjected to tensile stress for P
thirty minutes. This violates startup/cooldown criteria, which reiuires that the RCS pressure be high encugh to caintain the, cladding _in_co=pression when the temperature is greatcr than 100 F.
Eovever, violation.of this criteria does not imply clad failure. and no safety probics is predicted as a result of the
'depressuri:stien transient. Thu effi :ts of~this transient must be evaluated by Fuel Engi:eering with rcgsrd te f. 1 perfor=snce because the depressurization is not a design transient for evaluatics of f atigue life of the cladding. This 3
evaluation can be done after plc:t startup, ie.
there is not considered to be any potential f'or short-ter: adverse effects as a result of the depressuri:stion.
No restrictio:.s on plant startup, ccher thsn those already specified, should l
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be imposed at this ti=e.
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In order to fully assess ene implications of the depressurization event with
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regstd to fuel perf or=nnce it is necessar-/ or the following evaluation to be done:
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A) Ihcr=sl-Hydraulic Engineering should analy== the fuel ther=si performance during the trs=sient to deter =ine the internal fuel rod pressure.
B) Fuel Mechanical Design s=d Fuel Structure Analysis and Perfor=ance Unit t
should evaluate the ef fect,of the depres.suri:stion transient on cladding stress, strain, hydrido resrientat ion (strength), and fatigue.
L C) Thermal-Hydraulic F.ngineering should perform a Fuel Asse=bly lif t analysis for the critical point during the transient (spproxi=stely six minutes i
af ter reactor trip). In order to fully assa.ss the potential for asser.bly lift-off it is necessary for Co=trnl Analysis to provide Ther=si-Hydraulic Engineering with the predicted ACS flow rate (is the indicated flow accurate or must so=a correction bu applied?).
b.
D) If the lift analysis results in a prediction of fuel asse=bly lift-off, FM3 smst document the implications with respect to fuel assembly integrity (a safety evaluation of the affects-of lif t-of f has' been perfor=e d for Oconce 2 r.
with the conclusion being that there are no i=plicstions with regard to plant i
nafety).
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OCrosER 5, 1977 J. A. t>UER N r.
(!v the results of a core oo Thermal-Hydraulic Engineering should docu=cnt there are no concens with E
E) thernal-hydraulic evaluatios d ich shows that F.
regard to D5B or boiling in the core.
n-The esti=sted ecst of the above described evaluation is:
F CC 385 (THE) 140 s /o.5 Ca CC 381 (nc) 80 M1 1
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.., I. f j..a c-CC 387 (FSAP) 60 El I.
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CC:
J. S. Tulenko M
x", /, 8, Fuel Engineering Unic M.2saggr J. T. Willse g
W. T. Brunson R. M. Riatt H. W. Vilson R. Berchin R. P. Willia = son F. J. Levandoski 4
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