ML17037C361

Letter Enclosing a Report Relating to Malfunctions Which Occurred During Periodic Testing of the Core Spray Systems

ML17037C361
Person / Time
Site:	Nine Mile Point
Issue date:	07/24/1972
From:	Burt P Niagara Mohawk Power Corp
To:	Skovholt D US Atomic Energy Commission (AEC)
References
Download: ML17037C361 (10)

Text

e AEC DI IBUTION FOR PART 50 DOCKET MA TEMPORARY FORM CONTROL No; 4178 FROM: Niagara Mohawk Corp.

Lycoming, N.Y.

13093 P. Allister Burt DATE OF DOC: 72 DATE REC'D LTR 7-31-72 FI MEMO RPT VZHER TO Mr. Donald J. Skovholt CLASS:

U OP INFO ORXG 1 signed INPUT CC 39 No CYS REC'D 40 GENT AEC PDR SENT LOCAL PDR DOCKET NO:

50-220 DESQRIpZION:

Ltr trans t e o

owing:

ENCLOSURES; REPORT-Failure of Two Sets of Core Spray Pumps to Start During a Periodic Test PLANT NAMES: Niagara Mohawk Power Corp.

FOR ACTXON XNFORMATION L

7"31"72

.IMI IKII(j K%I.mt;EP BUTLER L W/

Copies CLARK(L)

W/

Copies GOLLEB(L)

W/

Copies KNIEL L W/

Copies SCHWENCER(L)

W/

Copies szorz(r.)

W/

Copies VAQSALLO L W/

Copies H.

DENTON W/

Copies SCHEMEL (L)

W/

Copies 2'IEMANN L W/QoopIee CHITWOOD(FM)

W/

Copies DICKER(ENVIRO)

W/

Copies KNIGHTON ENVIRO W/

Copies W/

Copies W/

Copies

. INTERNAL DISTRIBUTION' FX C PDR Gcp ROOM P>>506A AKING/STAIV tfCASE GIAIG3USSO AoYD-L(BIe)

DEYOUNG-L(PNR) lfSKOVHOLT L P.

COLLXNS

.gREG OPR

<FILE a: REGION (2)

EADRRIS ATEELZ HCH REVIEW

'NDRXE CHROEDER C

CARY'ANGE PAWLICKX HAO NUTH'.

STELID QYDORE HONPSON TEDESCO i40NG AaXNAS BENABOYA OLLIv~~

EWZOWOJ GBXMES GAYd4ILL KASTIEB 3ALLARD FXNE ENVIRO MULL'ICKER KNIGHTON YOUNGBEOOD PRO JLPCT LEADER HARLESS FA M SMILEX NUSSBAUMER LXC ASSTe SERVXCE MASON It1IISON KABX SMXTH GEARIN DIGGS TEETS WADE SHAFER BBot1N

@AT IM)

BRAITMAN SALTZMAN FLAWS MODOMALO DUBE O'. MILES A>>LOCAL PDR

Oswego, N.Y.

~

~

-vzrE(LAUGHrzN

-NSIC(BUCHAI+N) 1-ASLB>>YORE/SAYRE WOODWARDfHe ST.'16-CYS ACRS HOLDING EXTERNAL DXSTRXBUTXON 1 (5)(9)-NATIONALLAB>170>>GT 1 CONSULAIfl'S NEWMARK/Bah/AGABIAN 1 PDR-SAN/LA/NY l-DR, LEVINE BROOKHAVEN NAT. LA3 1 BOLANDp XDAHO FALLSp IDAHO(50-331 Only) 1 RD e ~ deejIAIiER e, e I'09GT

~

~

4 ~ '

~

0 op~

IIZgq gets.sg 1972 REGUQq)gy htAII. SECgpt p CIGT CQpg GARA MOHAWKPOWER CORPORATION Regulatol

~b a)9'm; NIAGARA '~

MOHAWK Nine Mile Point Nuclear Station Post Office Box 32

Lycoming, New York 13093 July 24, 1972 Fife Cjj.

Mr. Donald J. Skovholt Assistant Director for Reactor Operations Division of Reactor Licensing United States Atomic Energy Commission Washington, D. C.

20545

Dear Mr. Skovholt:

4y Q'yp p

Re:

Provisional Operating License:

DPR-17 Docket No.:

50-220 Enclosed is a report relating to malfunctions which occurred during the periodic testing of the core spray systems.

The core spray systems at the Nine Mile Point Nuclear Station, Unit IIl consists of two automatically

actuated, independent, double-capacity systems.

Each core spray system has 100 percent cooling capacity from each spray header and each supply pump set.

Hach core spray system has a redundant set of core spray and core spray topping pumps.

Each set of pumps are independent and are powered from independent emergency power systems.

For the worst line break, resulting in a loss of coolant accident, a core spray flow of at least 3400 gpm is required.

This requirement is met by one set of pumps in either core spray system.

Although two sets of pumps failed during the test, two sets of pumps did perform their design function and provided a test flow in excess of 3400 gpm in each core spray system.

Although the failed pumps could not be operated automatically or remotely both pumps could have been operated locally.

The type of breaker mechanism used on this system can be operated manually by using a tool to charge the closing spring.

Two mechanical controls are available to close or trip the breaker.

Therefore, the automatic controls are backed up with manual local control should loss of all redundancy occur.

h

~

~

~ l

Mr. Donald J. Skovholt Assistant Director for Reactor Operations Division of Reactor Licensing USAEC July 24, 1972 Page 2

The problem with both sets of pumps was corrected and operationally tested the same day.

The remaining set of pumps were inspected to insure oper-ability when required.

Very truly yours, P. Allister Burt General Superintendent Nuclear Generation PAB:pw Enclosure

r V

f I

I I

,1

~

Regulatory

'its Cy.

FAILURE OF TIE SETS OF CORE SPRAY PUMPS TO START DURING A PERIODIC TEST-

~04.~%7itt ~

'ach set of pumps is powered from independent emergency power boards.

See'alfunctioned pumps were core spray pump ¹111 which is powered from bus ¹102 and core spray pump ¹122 which is powered from bus ¹103.

Core spray pump

¹121 which is on bus ¹102 and core spray pump ¹112 on bus ¹103 started, and operated as required.

The problem with both pumps was associated with the pump motor air circuit breaker.

The breakers are Magne-Blast Circuit Breaker type AM-4.16-350-1H manufactured by the General Electric Company.

CORE SPRAY PUMP ¹lll The problem with Core Spray ¹lll breaker was caused by a mechanical linkage which was binding.

The mechanical linkage is spring loaded consisting of a roller follower and 'linkage which operates an interlock switch.

The inter-lock switch is part of the breaker contxol circuit.

The purpose of the linkage and 'switch is to monitor th'e physical position of the breaker assembly which, can be raised or lowered by an elevator mech-,

anism.

The interlock switch allows the breaker to operate only in the fully raised or lowered position.

The binding mechanism would not operate which prevented the interlock st.tch from'closing, The open interlock switch prevents the breaker control circuit from'perating.

CAUSE OF THE MECHANICAL BINDING - ¹lil CORE SPRAY PUMP The binding was caused by two identical linkage plates whose holes were slightly misaligned.

The two linkage plates connect two lever arms together.

The misalignment of the holes caused the connecting pins to bind between the lever arms and the linkage plates.

The binding was great enough to resist the spring force.

CORRECTIVE ACTION - ¹lll CORE SPRAY PUMP A rat tail file was used to align the holes since the misalignment was very slight.

The mechanism was reassembled and free of any binding.

Inspec-tion of other breaker mechanisms showed no binding.

CORE SPRAY PUMP ¹122 The problem with core spray pump ¹122 was caused by a latch check switch in the breaker control circuit.

This switch blocks recharging of the closing springs during a closing operation until the closing operation is completed.

CAUSE OF THE MALFUNCTION - CORE SPRAY PUMP ¹122 The latch check switch contacts were burned and would not complete the power circuit to the spring charging motor.

,Since the spring charging motor would not operate the closing spring were not compressed.

The breaker can not be closed if the closing springs are not compressed.

I l,(

f I

L V

IK a

~"

F

'p \\

FAILURE OF TWO SETS OF CORE SPRAY PUMPS TO START DURING A PERIODIC TEST (CONT'D)

CORRECTIVE ACTION - CORE SPRAY PUMP 0122 f

The latch check switch was replaced and the breaker operated as required.

ft

)

,I and core spray pump 8

lc

,I

l ~

V

)I III

(

)

~,

~