ML20043A428

LER 90-025-01:on 891216,operator Inadvertently Selected Incorrect Control Rod,Then Selected Correct Rod When Error Realized.Second Control Room Operator Will Be Used to Assure That No Signal Failure Will Move Two rods.W/900515 Ltr

ML20043A428
Person / Time
Site:	Oyster Creek
Issue date:	05/15/1990
From:	Fitzpatrick E, Gayley R GENERAL PUBLIC UTILITIES CORP.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-90-025, LER-90-25, NUDOCS 9005220069
Download: ML20043A428 (5)

Text

m- '

i f,

,s -- q

, .ag ,,

I j st ,

.j ..'

p -.

k .

3 GPU Nuclear Corporation h, . ? Y ' ' .,

Post Office Box 388

- Route 9 South Forked River, New Jersey 087310388 609 971-4000 '

, Writer's Direct Dial Number:

May 15,1990'

'l U.S. Nuclear Regulatory commission Document-Control Desk Washington, DC 20555

Dear Sire' ,

Subjects Oyster Creek Nuclear Generating. Station.

Docket No 50-219 Licensee Event Report Revision Thim letter forwards one (1) copy of. Licensee Event-Report.(LER).No.89-02b, .

Rev.-1.- The analysis of Occurrence and Safety. Assessment section has beet-revised to clarify the conclusions of the Safety Evaluation whichlwas. performed-for this event. A bar'has'been placed in'tho'right side margin indicate-the revised wording.

Very truly yours, Lj q

I E.E. Fitzpattrick.

Vice President and Director-

\' Oyster Creek '

EEF/JJR jc (ler/Covltrasjc) a gg.

Enclosure f cc Mr. Thomas Martin, Administrator a

ION Q h Region I~

U.S. Nuclear Regulatory Commission i

5

$$' 475 Allendale Road King of. Prussia, PA 19406 3

(Q@

-70 Mr. Alexander W. Dromerick, Project Manager

{gzg U.S.' Nuclear Regulatory Commission  ;

.op Washington, DC 20555-

-NG N  !

Qg NRC Resitant Inspector

~op Oyster Creek Nuclear Generating. Station Forked River, NJ 08731 .

I P GPU Nuclear Corporation is a subsidiary of General Public Utilities Corporation i 4

i j

' N.

')

= ut munaa . v64rea,ooema a Ei a, noveo one . um ..

UCENSEE EVENT REPORT (LER)

,asiurv name ni soonet aummea ei -=

Ovster Creek Unit 1 015 l o l o I o l 211 19 1lOFh 14 f tT4 64 Inadvertent, Simultaneous Movement of Two Control Rods Due To Personnel Error j eve =r nave e ten maman ie, nement w te ni ofwen ,aciutiu urvosveo e oo=T= oav vean via. .ag;tti L*g; wo r= oav vaan *.ciutv a. oocnet =vusemes j

i o taloIole t i i 1

~ ~

1l 2 1l 6 89 8l9 0 l 2l5 0l 1 0 l5 1l5 9 l0 o isto to t oi t i

,,e,,,,,,, 1 e ae on, ,e so.s.rreo -1,o r e neou,nea.s.no o, . ... t , - nii l o= = ...non.,

. .I .I rui., ,

f a .mesin ne es.3M nt) ..F34snanel ftF16 6 n., i i .. n n.,

. ,e>

..=>en a. _ gagg o

x es .sei.ninsi es.rawann so.7m ien.senas assai Se 4.enintel . 73tenanst . 73estensealGi g:. Q s ..meentlev6 es.73essenal es.734en3Mul uo.eas co taer ,oa r e ten nei l ame vetermone muusen  ;

ameaCoos Roger Cayley 6p19 9 i 7;l - l4 4 1 (> l1 cometers one une con eac= rionsponent pastume esecameo em two mesent um M s a AaLe 's Cause SYeTets CoedPoneNT Mg8jC. age s s se eYffe eNT "'$' AC. p

['

' > :'w ' e I i ! I I I I i i i i t i i S 5 O 'M' i 1 I l i l l <

l I i l I l 1 8 'U aupptease.rvat assent expecteo ne neowT= oav vlaa sueusesion Hl m ur = ,. a " "

neermaer ruw . ,.w eurerso suewwo= omr1,

] no , asi 0 ,l 1 ,1 9 ;1 On December 16, 1989, at 0533 hours0.00617 days <br />0.148 hours <br />8.812831e-4 weeks <br />2.028065e-4 months <br />, a control Room Operator (CRO) was increasing power with control rods. The CRO inadvertently selected an incorrect control rod, realized the error and selected the adjacent, proper rod. Due to the manner in which the CRO operated the rod select push buttons, two control rods were simultaneously selected. The CRO did not immediately realize that two rods were simultaneously selected and initiated a rod withdrawal. Both selected control rods began to move.

l . Corrective actions were taken immediately to terminate rod movement.

The safety significance of this event is considered minimal. A Safety

( Evaluation concluded that the simultaneous movement of two control rods I with the reactor vessel head in place is within the design basis for the affected transients and does not constitute an unreviewed safety-j question. A supplemental LER will be submitted when an ongoing evaluation of transients with the reactor vessel head removed is completed.

t i.

! =,- -

l

l~ < l?

3- _

seer Pere med . u.s. neucksa3 5 Soutifoey Consessmoon ,

.. LICENSEE EVENT REPORT (LER) TEXT CONTINUATION amoveo o=e ao vio-o* .  !

tupints erJ146 Faceuty seassa sta pocaat asuessen 21 'Paes im Les asuessen tot nsa . ug*:,y, s,

• a y2,y

~ Oyster Creek Unit 1  !

0 l5 l0 l0 l012 h l 9 8 19 0 l 2l 5 -

011 0l 2 0F 014' 9 vert u . ====s. =. .we== aar m ma w tm -

DATE OF OCCURRENCE This. event occurred on Decemb'er 16, 1989, at 0533 hours0.00617 days <br />0.148 hours <br />8.812831e-4 weeks <br />2.028065e-4 months <br />. This event.was

• determined to be reportable on March 22, 1990.

F IDENTIFICATION OF OCCURRENCE s

Two control rods (EIIS Code AA)'were selected and moved simultaneously.,

This occurred while a control Room Operator was increasing power with--

control rods.: 'This event is reportable based on 10CFRSO.73(a)(2)(ii).

r r

L-CONDITIONS' PRIOR $ OCCURRENCE The reactor was in the RUN mode with a reactor coolant temperature of 520'F. Generator. output was approximately 380 MWo. The initial positions of the two affected control rods were: rod 14-27 at position 48 (fully withdrawn), and rod 18-27 at position 12.

l l DESCRIPTION OF OCCURRENCE l

On December 16, 1989, at.0533 hours0.00617 days <br />0.148 hours <br />8.812831e-4 weeks <br />2.028065e-4 months <br />, a control Room OperatorJ(CRO) was increasing power with control rods. The CRO intending to select, control rod 18 '27 . inadvertently selected en adjacent rod , 14-27. Realizing,the ,

error, the CRO. selected the proper control rod at the same time that the rod- select push button for the wrong control rod was being released. This .

resulted in both rode being irtadvertently selected at the same time. The CRO did not realize that two control' rods were se'lected and attempted to withdraw rod 18-27 by taking the rod control; switch to the " Notch Out" position. The reactor manual control system (EIIS ' Code JD) withdrawal sequence momentarily inserts the control rod to unlatch the rod so it can' be withdrawn. The CRO immediately recogniaed that both control rods'were moving in and quickly-took action to stop rod motion by turning off rod select power. This resulted in-both rods returning to their original ,

positions. Plant management was immediately notified.

APPARENT CAUSE OF OCCURRENCE-This event was caused by personnel error. The two cor. trol rod select':

switches 14-27 and 18-27 are adjacent to one another. The CRO depressed the rod select push button for control rod 18-27 at the same time that the.

rod select push button .for this wrong control rod 14-27 was being released. ,

b N$OU M

.sg. 1 h . , _ _ . , , , , . . . _ _ _ _ _ -44 -- -- - - - - - - ------__----4

. ~., ' :.

ac b= men u s =vetus :vmoav commissio

. LICENSEE EVENT REPORT (LER) TEXT CONTINUATION - . aovec ome no uw-oios in.... sm

1. AC16 sty eaa.sg tip pocusi seuesen GB (gn asyunga ag) , ace la

,0.. . am, ** ;

nag;

.: Oyster Creek. Unit 1 0 l510101012 [1- l 9 8 19 0 (2 l 5 -

0l1 00 0F 0 l4 tecto.- . c an.wnn .

I- ,

ANALYSIS OF OCCURRENCE AND SAFETY ASSESSMENT The Reactor Manual Control System (RMCS) :(EIIS Code-JD) utilizes relay-sequencing to control the operation of rolenoid- operated valves in the control Rod Drive Hydraulic System. . These valves direct high pressure water to the control rod drive . mechanism in order to move the control -

I rod . . .Various switch contacts, including . the rod select . push button contacts, and an automatic sequencing timer within the system are utilized in the relay control logic.

Circuitry within the reactor manual control system is intended to prevent.

the selection of more than one control rod at a time. This circuitry can be defeated if contacts within the rod select push button are not properly; made or disconnected when'a rod select push button'is actuated.- This can.

occur when a rod select pushbutton is held mid position and another rod select pushbutton is depressed such as occurred during this event, or, it could occur as a result of a rod select pushbutton malfunction. .There is no single component failure that would cause more than-two control rode to

..1 be withdrawn at the same time. Therefore, this analysis considers'only two control rode being withdrawn at one time due to an operator error or single component malfunction.

t A Safety Evaluation was performed to determine whether the simultaneous movement of two control rods was outside. the design basis for Oyster Creek j and, therefore, might constitute. an unreviewed safety question. . The -

following' were analyzed with respect. to .the event

Single- Failure Criteria, Rod Worth Minimizer (EIIS Code ID) Operation,, Uncontrolled l Control Rod Withdrawal from a Suberitical or Low Power Startup Condition,

, L

!- Uncontrolled Control Rod Withdrawal at Power, aind the Control Rod Drop

! Accident. The safety functions of the three systems that could be }

!- affected by the event were evaluated. Those systems are the Reactor Manual control System, the Rod Worth Minimizer and the Reactor Protection Syotem. (EIIS Code JC).

The Safety Evaluation concluded that the simultaneous movement of two control rods while the head is on the reactor vessel is within the design, basis of the Oyster Creek Plant for the af fected transietn.s at power. To address a rod drop accident possibility or a continuous control rod withdrawal from low power, a second CRO (in addition to the RWM) will be used to assure that no single failure will move two rods ' simultaneously at startup.

i

The significance of thio event was further mitigated by the f act that one of the two control rods was already fully withdrawn to position 48.

4

• 9 OO$M M

1-ass e asea . - u s auctsaa natut.seone c--

r . , . - LICENSEE EVENT REPORT (LER) TEXT CONTINUATION'- amovio ome ao ow-om 'I l , in = ss een p ..eiurv n m ooe .,num a m ua u a <e> ~ ... is J vs'a '

"MMP - O f:

Oveter creek.' Unit 1 01510101012 p- l 9 8 l9 - O p l5 -

0l1 0 l4 0F 0[4 1 xt e . ac a asuwnn I

L CORRECTIVE ACTIONS 1

Immediate

l. .

- Reactor manual . control system rod control power"was secured. .This stopped '

the . rod withdrawal sequence and allowed the 'affected control rods ' to . i

return to their original positions.-

\'

Rod .18-27 was subsequently wir.hdrawn to its programmed position - (Not'ch '14) . .

3 to provide a synunetrical: rod pattern. 4  !

1= f' An administrative rod' block was initiated which prevented any further withdrawal of: control rods.

The operability of the rod ' select / deselect , and control: rod positio'ning <

functions of the Reactor Manual . control System were tested and.were' found :t to.be satisfactory. ~A second .' licensed operator . was stationed at the control panel to verify that - only one ' rod- was selected- during :tihe withdrawal / insertion of control' rods.

Lono Term Plant Procedures will be revised to include provisions to minimite the probability of inadverte'nt simt.ltaneous withdrawal of two control rods >

where appropriato.

The event will be studied further to include . transients with the ' vessel head removed = to determine if any' additional ' testing,- maintenance or i

modifications are warranted. A. supplemental LER will be submitted when

!- the ongoing evaluations have been finalized.

SIMILAR OCCURRENCES None r

7. ,

4

j. ',

80AM M i

- _. - . _ . . . .. ._ -- . _