ML20205P481
| ML20205P481 | |
| Person / Time | |
|---|---|
| Site: | Quad Cities  |
| Issue date: | 05/08/1986 |
| From: | Bax R COMMONWEALTH EDISON CO. |
| To: | NRC OFFICE OF ADMINISTRATION (ADM) |
| References | |
| 0541B, 541B, RLB-86-55, NUDOCS 8605210428 | |
| Download: ML20205P481 (1) | |
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O Commonwealth Edison Quad Cities Nuclear Power Station 22710 206 Avenue Nodh Cordova, Illinois 61242 Telephone 309/65 & 2241 RLB-86-55 May 8, 1986 U.S. Nuclear Regulatory Commission Document Control Desk Hashington, D.C.
20555
Reference:
Quad Cities Nuclear Power Station Docket Number 50-254, DPR-29, Unit One Enclosed please find Licensee Event Report (LER)86-020, Revision 00, for Quad Cities Nuclear Power Station.
This letter corrects the original cover letter transmitted with this LER which incorrectly stated the LER number as85-022.
This report is submitted to you in accordance with the requirements of the Code of Federal Regulations, Title 10, Part 50.73(a)(2)(iv), which requires the reporting of any event or condition that results in actuation of any Engineered Safety Feature.
Respectfully, COMMONHEALTH EDISON COMPANY QUAD CITIES NUCLEAR POWER STATION R. L. Bax Station Manager RLB/MSK/cmd Enclosure cc: J. Hojnarowski A. Madison INP0 Records Center NRC Region III 8605210428 860508 PDR ADOCK 05000254 s
't 0541B e
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LICENSEE EVENT REfCRT (LER)
Dicket Numbir (2)
Paae (3)
' Facility Name (1)
OUAD-CITIES. NUCLEAR POWER STATION. UNIT One 015101010121514 1
of 0 3
' Title (4) Unit 1 Spurious Group I Isolations Caused by Instrument Rack Vibrations
'nt Date (51 LER Number (6)
Reoort Date (7)
Other Facilities Involved (8)
/ Revision Month Day Year Facility Names Docket Nymjerfs)
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Sequential //p
/,p/p Day Year Year
//
Number
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Number 01 51 01 01 01 I i 013 218 816 816
~~
0 l 2 10
~~~
010 014 212 816 01 51 01 01 01 1 1 OPERATING MODE (9) 2 20.402(b) 20.405(c)
_1_ 50.73(a)(2)(tv) 73.71(b)
POWER 20.405(a)(1)(1) 50.36(c)(1) 50.73(a)(2)(v) 73.71(c) 0l0 l0 20.405(a)(1)(ii) 50.36(c)(2) 50.73(a)(2)(v11)
Other (Specify LEVEL 20.405(a)(1)(iii) 50.73(a)(2)( t )
50.73(a)(2)(viii)(A) in Abstract below flo) 20.405(a)(1)(iv) 50.73(a)(2)(ti) 50.73(a)(2)(viii)(B) and in Text) 20.405(a)(1)(v)
_._ 50.73(a)(2)(iii) 50.73(a)(2)(x)
LICENSEE CONTACT FOR THIS LER (12)
TELEPHONE NUMBER Name AREA CODE Alar J. Blamey. Technical Staff incineer. Ext. 2174 3 10 l9 61 51 41 -l 21 21 411 COMPLETE ONE LINE FOR EACH COM FAILURE DESCRIBED IN THIS REPORT (13)
CAUSE SYSTEM COMPONENT MANUFAC-REP 0kTABLE CAUSE SYSTEH COMPONENT MANUFAC-REPORTABLE TURER TO NPROS TURER TO NPRDS I
I I I I I I I
I I I I I I I
I I I I I I
/
I I I I I I I SUPPLEMENTAL REPORT EXPECTED f14)
Expected Month l Day l Year Submtssion
'es (If Yes. comolete EXPECTED SUBMISSION DATE)
X l NO l
l ll I
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JRACT (Limit to 1400 spaces, i.e. approximately fifteen single-space typewritten lines) (16) i At 1030 hours0.0119 days <br />0.286 hours <br />0.0017 weeks <br />3.91915e-4 months <br /> on March 28.1986 and at 1347 hours0.0156 days <br />0.374 hours <br />0.00223 weeks <br />5.125335e-4 months <br /> on April 2,1986. Unit One received spurious Group I Isolation signals. Unit One was shutdown for a refueling and maintenance outage in the REFUEL mode prior to the events. The cause of the two Group I Isolations was actuation of the main steam line high flow switches due to instrument rack vibration. The March 28 trip occurred when a contractor dropped a pipe on Instrument Rack 2201-10. The April 2 event was caused by an inspector inadvertently striking the same instrument rack.
Root cause of these occurrences is personnel error. A contributing cause is the sensitivity of the main steam line flow switches to trips of this type. The switches are manufactured by Barton, model number 278.
The switches were known to be sensitive and barriers were being installed around the instrument racks containing these switches when the trips occurred. Long term corrective action is to investigate the replacement of the switches with an analog type. All station departments and contractors were also reminded of the importance of being careful when working around sensitive equipment and to notify Operating Engineer for review and approval of job conditions. This report is submitted in accordance with the requirements of 10 CFR 50.73 (a)(2)(iv), which requires the reporting of any event or condition that results in actuation of any Engineered Safety Feature.
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LICENSEE EVENT REPORT fLER) TEXT CONTINUATION DOCKET NUMBER (2)
LER NUMBER f6)
Pace (3)
FACILITY NAME (1)
S;quintial Revisiin g///
YIar Number
///: Number
' d Cities Unit One 01510 f010l 21 51 4 816 0 l 210 0 10 012 0F 013 PLANT AND SYSTEM IDENTIFICATION:
G;neral Electric - Boiling Water Reactor - 2511 MWt rated core thermal power. Energy Industry Identification System (EIIS) codes are identified in the text as (XX].
IDENTIFICATION OF OCCURRENCE:
Spurious Group I Isolations caused by instrument rack vibrations due to contractor personnel bumping racks.
Discovery Date:
3/28/86 Report Date:
4/22/86 This report was initiated by Deviation Report 0-4-1-86-42 CONDITIONS PRIOR TO OCCURRENCE:
REFUEL Node (2) - Rx Power 07. - Unit Load 000 MWe REFUEL Mode (2) - Refuel - In this position interlocks are established so that one control rod only may be withdrawn when flux amt,11fiers are set at the proper sensitivity level and the refueling crane is not over the reactor. Also, the trip from the turbine control valves, turbine stop valves, main steam isolation
[~M1ves, and condenser vacuum are bypassed. If the refueling crane is over the reactor, all rods must be
(
,11y inserted and none can be withdrawn.
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DESCRIPTION OF OCCURRENCE:
At 1030 hours0.0119 days <br />0.286 hours <br />0.0017 weeks <br />3.91915e-4 months <br />, on March 28, 1986, and at 1347 hours0.0156 days <br />0.374 hours <br />0.00223 weeks <br />5.125335e-4 months <br />, on April 2, 1986, Unit One Reactor received spurious Group I Isolation signals. The 901-5 panel alarms in the control room indicated that the isolation signals were caused by main steam line high flow. Unit One was in the REFUEL mode prior to the events.
This report is being submitted in accordance with the requirements of 10 CFR 50.73(a)(2)(iv), which required the reporting of any event or condition that results in actuation of any Engineered Safety Feature.
APPARENT CAUSE OF OCCURRENCE:
The cause of the two Group I Isolations was due to spurious actuation of the main steam 1tne high flow suitches from instrument rack vibration caused by contractor personnel working near the 2201-10 Instrument Rack.
The March 28 event was caused by a contractor dropping a pipe on Instrument Rack 2201-10. The April 2 event was caused by a Quality Control Inspector contractor inadvertently striking Instrument Rack 2201-10 during the inspection of welds on the newly installed protective cage around this rack. Instrument Rack 2201-10 contains differential pressure switches which provide high main steam flow signals to the Primary Containment Isolation (JM] logic in a one-out-of-two-twice logic arrangement. The rack ts located in the Residual Heat Removal System (RHR) (80] rooms.
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LICENSEE EVENT REPORT fLER) TEXT CONTINUATION FACILITY NAME (1)
DOCKET NUMBER (2)
LER NUMBER f6)
Pace (3)
/p/,/p Sequential
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Revision Year
,///
Number
///
Number
^--d Cities Unit One 0l5 l 0 1 0 l 0 1 21 51 4 8 l6 0l 2 10 010 011 0F 013 The root cause of these occurrences is due to personnel error in coming in contact with the instrument racks. A contributing cause is the sensitivity of the main steam high flow switches to vibration or inadvertent contact. The contractors were in the process of installing a barrier around the racks to prevent spurious trips when the trips occurred.
ANALYSIS OF OCCURRENCE:
A Group I Isolation signal clases the Main Steam Isolation Valves (MSIVs), steam drain valves, and recirculation sample valves. If this incident occurred at any power level in the RUN mode, the reactor would scram when the Main Steam Isolation Valves reached 10 percent closed from the full open position. This scram is in anticipation of the pressure and flux transient which would occur upon full closure of the MSIVs.
However in this incident the reactor did not scram because the scram function given by MSIV 10 percent closure is bypassed in the REFUEL mode. The were no safety consequences as a result of a Group I Isolation signal with the unit shutdown.
CORRECTIVE ACTION:
Action Item Record (AIR) 86-04 has been initiated to investigate replacing the presently installed differential pressure switches with analog devices, which are less susceptible to the spurious trips of this type. The current switches are renufactured by Barton, model number 278. In the interim, the Station is placing barrters around the racks. The eventual replacement of the Barton switches with anolog devices will prGyent recurrences of this type.
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,Iitionally, all station departments and contractors have been reninded of the importance of being careful
'- - :n working around instrunent racks or sensing lines, whether the unit is operating or shutdown. Any work or inswection which has the potential to come in contact with sensitive equipment is to be brought to the attention of the Operating Engineers for their review and approval of the working conditions.
FAILURE DATA:
Thsre have been several occasions in the past where inadvertent contact with instrument racks bas caused a reactor Group I isolation and/or scram. The most recent occurrence was on January 3.1986, when a spurious high steam line flow signal caused a Group I isolation and scram on Unit Two. This incident is recorded in Unit Two LER 86-01.
Unit One LER 86-19 docunents a spurious Anticipated Transient Without Scram System initiation from a bumped instrument rack,
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