ML20084G160

Ao:On 691002,startup Test Program Did Not Meet Insertion Times of Control Rods.Wire Mesh Will Be Removed,External Filters Will Be Exchanged & Scram Insertion Times Will Be Monitored

ML20084G160
Person / Time
Site:	Oyster Creek, 05000000
Issue date:	10/14/1969
From:	Kelcec G JERSEY CENTRAL POWER & LIGHT CO.
To:	Morris P US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20084G120	List: ML20084G117 ML20084G153 ML20084G160
References
NUDOCS 8304210507
Download: ML20084G160 (4)

Text

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REFERE! CS 10,f .

. , r-Joi say Colltl til Powde & Ligrit uusin inuiy 1 ,

l

} M ADttoN AVENU C AT PUNCH Dom. Ro AD 9 M oR HIS tow N, N. J. 07300 0 539 6113 1

Detaber .1h, 1969 4

Dr Peter t.. Nerio, d reetar Division of ac t.c l Lice nn: ~

Unitcs! Ct utec /,tomie .

no y Co:mi: clon b'n s h ing t on , D C. EO M Re: Eeport of Abnormal Occurrence

Oycter Creek Huclear Generating Station, Unit No. 1 October 2, 1969 Gen tler en

EuhiECT:

The inability to ' wet a liuiting condition for oper(tion at th+. Cyster Crc eh Haeleur @neratin , Station of the Jercey Central Power a:n1 Light Com-puny en October 2, 1969 Reference / EC Operating License DPPc-16, Technica3 Or;elfications, thereof, Ocetion ;;.2 "Feactivity Control," Opecification !!,

Sub-Upe irication 1i0. 3 "The averece of the scra::: insertion times of all opecuble control rods ch211 be no greater than: . . . ."

CITUATION:

In the course of proceeding with the start-up test progran of the Oyster Creek reactor, the reactor had been operatin7 with all control rodn operable and a total of 113 control rods fully or partially withdrawn from the core.

itluc durinr thin progre, twenty-cix (26) of the control rods that are fully withdrawn during Tower operation are continuously monitored for scran incer-tion time to that data can be obtained in the courne of transient teating, when acrues cou]d occur. During nuch tecting, a scrn": occurred at 9: CS a.m.

on Oc tober 2,19G9, nnd it vac obcorved that the incertion times for thece tuenty-aix drivec did not, in their entirety, meet the limitin~, conditionc for operation ac specified in the technical apecifications. Each of the celeeted drivea met, the 10 percent incertion time requirement of 0.7 seconda with an averaf; . of api:roxhnately 0.h36 cecondc. The act,ual average for the 50 percent. incertion time van approxincitely 2 509 seconda au compared to a LCO of 2.05 necondn; and for 90 perecnt inscrLion, the act,ual average wac npieuxim itely 5.793 seconds un co: spared to the Lc0 of 5 0 ceconda. subaequent tenting of addit,iun'tl cont.rol rodn reculted in the cohelualon that the pro-blera was of n, e,enera] nature. The Division of Compliance .:an notified of t, hic abnormal occurrence an required by the Technical Specificationn.

8304210507 700306 ATTACH 12h"f 2 PDR ADOCK 05000219 G _

PDR ._ _. _

Pat;e 1 of 15

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.l October lh,19@

Dr. Peter A. Morris i 1- l I

! l t 4 l CAUSE AND HI?.3ULTC:

1 Examination of the drivcs disclosed the fact thrtt the internal and externai filters within the drive vere partially plugged with a very fine red iron oxide. The internal filters, composed of se'rine wire mesh of I approximately _three micron r13 teriny capseity, were pluc,y,ed to the extent j that the floa of Ieactor water into the volu c between the stop pinton and j the-Cop of the inder tute during a scram operation was excessively restricted.

When this occurred, the pressure unbalance across the top of the index tube ,

caused an increase in the scrnu insertion time for the drive. This fact  !

j van confirmed by retesting selected drives uithout the fine internal filter j in place, at which tine the drives tested in this manner more than met the

ceram insertion time specified. (See attached Exhibit A for a cross section i of the drive shoving the internal and external filters and the flow path l

of water when withdrcwing and inserting the drives).

~

j Inasmuch as reactor water flows through the internal filter on every insert and ceram signal, the " rouse-like" oxide had to come from the vessel j

vater rather than the control rod drive hydraulic system. Internal inspection of drives and various locations in the hydraulic nyctem confirmed the reactor j j

vater to be the source. Along with the increases in power level during the  ;

start-up test program, auxiliary systems (condensate and feedwater) have been exper.iencing increased flous and stec:a systems have been brou.ght into service for the first time (i.e. turbines, condenser, reheaters, and extrac-i tion stema feedwater heating). It is believed that the source of the oxide is from the carbon stec1 equii cent associated with these auxiliary systems, i Separation of this oxide and other foreign matter from reactor water occurs I by settling in the condenser hotvells and by filtering in the condensate denincralizer beds. During this period of power testing, water quality remained within the specified limits. The precise mechanism for the ,

l accumulation of iron oxide and the exaggerated tendency to plug the drive I i

? filters is not clearly understood. It is our understtmding that a similar

phenomenon was enecuntered at KRB, but the plugging was of lesser magnitude and ceram times reached equilibrium within specified limits after the initial  ;

)

startup period.

1 l i

CORRECTIVE ACTION TAKEN:

.i i t J

Based upon the control rod drive manufacturer's recommendation,- the  !

I fine wire mesh ont ' he internal filter vill be removed on all of the 137 'i drives. (Consideration is being given to reinstall a small number of fine filters in order to obtain additional data). In addition, the external

! filters vill be exch w ed for clean filters on all of the 137 drives.

i With the removal of the fine wire mesh from the internal filter, the  !

l j reactor water vill now i> ass through the filter support basket which in a - l l

cylinder perforated with 5/32 inch holes. 'fhe fine oxide cannot plugj

- t j

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J Dr. Peter A. Morris October lh, 19@

i i

i.

i these op'ennings, and therefore, the LCO for ceran innertion time will con-tinue to be cet. The effect of the fine raterial upon the drive internalc ,

i (incide of index tube and utop picton coals) muy be increened wear of the stop piston cealc, howcVer, there is no reason to believe that it vould l 12 creace the cerca incertion time of the drive or the ability to fully ,

incert the rods.

}

1

' In addition to the above modifications, monitoring of the cera'n incer-tion times will contint.e, seul lenhge will be measured for cach fully with-drawn rod, condcocate de:nineralizer operation vill be reviewed with parti-l cular attention beiny given to oxide carryover, and each hot well vill bc  ;

c1 caned of the acentulated foreicn material. j UUCLDiR SAFUfY SIGUIFICAUCE:  ;

The slow cera!n incertion timen accociated with thic event did not recolt in any nuclear safety problems. All control roda were fully incerted into the core and al] drives were f acter than the time required for 10 per-cent incertion. There serc no Limitina Cafety Cyntv1 Settings violated.

The neutron flux did not exceed itc ceran cetting for longer than 2.5 seconds; 2 in fact, it returncd to ita trin actting in approxinately 0.3 ceconds.

b t +.4 oc nL An additionul off 7tite tect was performed uherein the manufacturcr J

comnletely cealed the/rine mech filter. Even with the filter in this con-3 dition, the drive completed its full travel and would not have failed to l

4 nerara. The incertion time vac greater than that experienced with the  ;

l partially plugr,ed filterc at Oyster Creek. It is not likely that the fine l ctrainer would be completely plugged during the operation, but even with ,

T conp]ete plugging tgforce balance encures a nct upward force to cauce the scram. -

l Very truly yours, l N C, ~ o b e cs~us t T.~'~- ,

mu wx do u6 ~ '. .

2, .' .

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l bN wb o c.,e ,.s j \ jt<\7

'Ccorge Kelece c,A(#( Manager Generating Glationc i - 14 0< wj, r.

rx \ \ cg, CK;ja 'g

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j CC: R. W. Kirkman, Director i

Division of Compliance i

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EXHIBIT A i Schematic Diagram - ?.!c, del 7H-DD-10-Al Cor. trol Rod Thrive Mech mirim  !

a ATTAC m tr 2  !

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