05000249/LER-1977-034, Regarding an Interruption in the Feedwater Flow Signal to the Circulation System

Regarding an Interruption in the Feedwater Flow Signal to the Circulation System

ML17252A336
Person / Time
Site:	Dresden
Issue date:	08/18/1977
From:	Stephenson B Commonwealth Edison Co
To:	James Keppler NRC/RGN-III
References
BBS Ltr. #77-762 LER 77-034-00
Download: ML17252A336 (3)

LER-1977-034, Regarding an Interruption in the Feedwater Flow Signal to the Circulation System

Event date:
Report date:
2491977034R00 - NRC Website

text

Commonwealt9dison Dresden Nuclear Power Station R.R. #1 Morris, Illinois 60450 Telephone 815/942-2920 BBS Ltr 1177-762 James.G. Keppler, Regional Director August 18, 1977 Directorate of Regulatory.Operations.:.. Region III U.S. Nuclear Regulatory Commission 799 Roosevelt Road Glen Ellyn, IL 60137 Enclosed. please find Reportable Occurrence Report #50-249/1977-34.

This report is being submitted to your office in accordance with the.Dresden Nuclear Power Station Technical Specitications, Section 6.6.B.

BBS:dlz F;,iiclosure cc:

Director of Inspection & Enforcement*

B.B. Stephenson Station.Superintendent Dresden Nuclear Power Station Director of Management Information & Program Control File/NRC

9-ICEN$EE EVENT. REPORT 9 CONTROL BLOCK: I 1

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[PLEASE PRINT ALL REQUIRED INFORMATION]

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LrcENSEE

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NAME

@El (11 LI nlR Is 12 I 7

8 9.

14 CATEGORY REPORT TYPE 6

LICENSE NUMBER I o I o 1-1 ol 01 01 01 o 1-1 ofll o I 15 25 REPORT SOURCE DOCKET NUMBER LICENSE TYPE I 41 l I l I ll i1 26 30

• EVENT DATE EVENT TYPE I 0 1-1 1 31 32 REPORT.DATE

@E]coN'T I I I lLJ w I ol sl ol-1 ol 214 19 I I 0 I B I 0 I 4 I 7 I 71 I 0 I B I l I BI 7 I 71 7

8 57

. 58 59 60 61 68 69 74 75 80

• EVENT DESCRIPTION

@lg) Inuring routine maintenance on the Feedwater System a feedwater flow signal to the re-I kJ 91 i 1

i r:~

• d

• ~1

.-------, ~-T-h 1 -

• • f""- -R=-Fw--r* ~ -~

001

~ c rcu at on system '~as *;Lnau.;v:*ett~~nt y-.in*t:er:i;-up~u~i~--' es osst.o :c_,t __,.:_e~~g-~;;:::~-;-:_::::.;

7 8 9 80 lol41 I ected the recirculattng water pumps tci go toward the minimum speed setting *. The "B" I 7 8 9

80.

lol5l I recirc. pump started to reduce sp_~ed but the "A" pump did not and ultimately a 20%

I 7 8 9 80 (filID !mismatch in recirc. pump speeds occurred.

The recirculation system "Mismatch" I

7 8 9 PRIME (CONTINUED) 00 SYSTEM

CAUSE

COMPONENT COMPONENT CODE CODE COMPONENT CODE SUPPLIER MANUFACTURER VIOLATION

@El I c I 1Bil W IRIE IL I Al YI xi L!J I BI o I 4 Io I

~

7 8 9* 10 11

. 12 17 43 44 47 48 CAUSE DESCRIPTION lol0I I The "A" recirculating p~p did not runback to minimum speed because the operator 7

8 9 I

80 lol9l I turned off the control power to the "A" pump inadvertently before the system could I

7 8 9 E:@J I respond to the decrease signal command.

7 8 9 FACILITY

'% POWER STATUS OTHER STATU.S EEJ lJJ I o I 91 21 NA I

7 8 9

10 12 13 44 FORM OF ACTIVITY CONTENT rn RELEASED OF RELEASE AMOUNT OF ACTIVITY I

LB

~I NA 7

8 9

10 11 44 PERSONNEL EXPOSURES NUMBER TYPE

DESCRIPTION

[IEJ I ol ol g L1J 7

8 9 11 12 13 PERS"ONNEL INJURIES NUMBER

DESCRIPTION

EEi I ol o Io I 7

8 9 11 12 OFFSITE CONSEQUENCES [ili]

7 8 9 LOSS OR DAMAGE TO FACILITY TYPE

DESCRIPTION

(2))_ lzJ 7

8 9 10 PUBLICITY E0 7

8 9 ADDITIONAL FACTORS GE 7

8 9 80 The operator had intended to tBurn off control!

METHOD OF DISCOVERY "L!J 45 46 45 NA NA NA NA NA NA (CONTINUED) 9o DISCOVERY DESCRIPTION NA LOCATION OF RELEASE NA

• 80 80 80 80 80 80 80 80 80 NAME: _______

c_a_r_l_L_i_n_d_b_u_r.;:::g _________ _

PHONE:

314 GPO 881

• 667 circuitry should have prevented a speed mismatch in excess of 10%, as stated in the Tech. Specs.

The safety implications of this event were minimal be-cause the excessive speed differential was immediately corrected.

This event is not a repetitive occurrence.

(50-249/1977-34) power to the "B" recirculating pump to stop it from running back further.

The cause of failure of the "Mismatch" circuit is unknown at this time.

The most probable cause was the temporary failure of the K-6 relay which should have "opened" and prevented a speed reduction of the "B" pump beyond the 10% limit.

Although this is not known to be the cause of this event a similar type relay in another portion of the system has previously failed to open when required.

The "Mismatch" circuit was tested electronically by simulating signals and observing speed control response, and by actually separating the speed of the recirculating pumps.

In both cases the system functioned as designed.

The K-6 relay was replaced as being the most probable cause of failure.

To prevent reoccurrence a surveillance program will be implement'ed which will annually assure the operability of the "Mismatch" circuit.