ML20095B263
| ML20095B263 | |
| Person / Time | |
|---|---|
| Site: | Quad Cities  |
| Issue date: | 03/27/1992 |
| From: | Kovach T COMMONWEALTH EDISON CO. |
| To: | Davis A NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| Shared Package | |
| ML20095B221 | List: |
| References | |
| CAL-III-92-06, CAL-III-92-6, NUDOCS 9204220062 | |
| Download: ML20095B263 (6) | |
Text
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O' Downers Grove, tilinois 60$15 March 27,1992 Mr. A. Bed Davis Replonal Administrator United States Nuclear Re9ulatory Commission 799 Roosevelt Road Rill Glen Ellyn, Illinois 00137
Subject:
Quad Cities Station Response to Confirmatory Action Letter (CAL Rill 92 006)
Regarding Quad Cities Unit 2 Scram of February 7,1992 NBC.Dochet Numbere_50:251and_50:205
Reference:
(a)
Confirmatory Action Letter (CAL Rill 92 006) from A. Bed Davis (NRC) to Cordell Reed (CECO) dated February 7,1992, i
(b)
H.J. iAiller letter to Cordell Reed dated February 28,1992 transmitting NRC Inspection Repod 50 254/92007
Dear Mr Davla:
Enclosed is Commonwealth Edison Company's (CECO) response to the subject Confirmatory Action Letter (CAL) and referenced Augmented Inspection Team (AIT)
Repod. The issues cited by the CAL are addressed in Attachment A. The concerns i
hl hlighted in the AIT Report transmittalletter are addressed in Attachment B.
9 If your staff has any questions or comments concerning this response, please refer them to John Schrage, Nuclear Licensing at (708) 515 7283.
Sincerely,
!Yl/W
/
Nuclear Licensing Manage k T.J. Kovach -
Attachments
[
cc:
USNRC Document Control Desk L.N. Olshan, Project Manager, NRR T. Taylor, Senior Resident inspector RR 3 01992 9204220062 920417 PDR ADOCK 05000254 P
. ppg ZNLD/1644/1
,. ~
ATTACHMENT A RESPONSE TO_ CONFIRMATORY ACTION LETTER CAL Rill 92 000 As contained in the transmitted CAL, five specific actions were required to be periormed.
These actions and their status follows:
1.
Conduct an Investigation to determine the cause of:
a.
The f ailure of HPCI stop valve H012317 b.
The failure of the "C" relief valve c.
The apparent f ailure of the reactor feed pumps to automatically trip at the appropriate vessellevel and related operator actions d.
The reactor scram e.
The apparent anomalies associated with the main steam line flow instruments f.
Other failures which may be subsequently identified during the AIT evaluation of the event STAIUS On February 18,1992, the station issued its final investigation report (GCT 92 008) for the event in question. The investigation team was chartered with determining the root cause of the scram and associated equipment failures. The root cause of the scram focused on the apparent f also signal of a main steam line break as sensed by the high flow differential pressure switc aes. An exhaustive search and testing program was conducted over the course of the investigation which showed the switches were performing 3roperly and have a history of accurate and rollable service. The conclusion o the investigation team was that the root cause of the scram could not be determined and a recommendation was made to instrument the high flow switches to provide furthor monitoring diagnostics.
The fallod HPCI stop valve was determined to be caused by inappropriate work instructions for the overhaul of the valvo during the refuel outage in February 1991.
The failure of the "C" relief valve to open was caused by vibration induced wear which caused a fine dust to settle in the cut out switch contacts resulting in loss of conunuity when the valve was called on to open. Significant enhancemerits i:t the maintenance of the relief valve actuators have been implemented to ensure lur'ner failures do not occur. The cause of the reactor feedwater pump not to t!p on high reactor water level was instrument setpoint drift.- Operator response to this was determined to be appropriate. The reactor feedwater pump trip switch was recalibrated and veritled to trip at the proper setpoint. The spiking of the main steam line flow indicator was detelmined to be a faulty power supply. All four main steam line flow indicators were recalibrated or replaced to ensure proper readings prior to start up.
- ZNLD/1044/2 1
1
ATTACHMENTA BESEONSE TO_ CONFIRMATORY _ ACIlON LETTER CAL Blli 92 006 (continued)
This action is considered complete. A copy of the report has been provided to the NRC Senior Resident inspector. Questions on the report should be directed to Mr.
G.C. Tietz, Technical Superintendent, Quad Cities Station, (309) 654 2241 Ext. 2214.
II.
Place the "C" rollef valve and the HPCI stop valve H012317 in quarantine until released by the NRC AIT.
SIAIUS The *C" relief valve and HPCI stop valve H012317 were placed in quarantine and subsequently released by the AIT lead investigator.
Ill.
Maintain documentary evidence of your investigation effort and make this evaluation available to the AIT.
STAIUS All dncumentation utilized during the investigation is on file at the station. All of this information was made available to the AIT during their investigation.
(V.
Evaluate these most recent equipment f ailures and operator actions in "ght of past equipment f ailures and operator performance to determine if additional actions are necessary.
SIAIUS We investigation team made an evaluation of equipment aeriormance on operator performance. This was done in an attempt to assess if a crend of equipment f ailure was occurring that could be impacting the operators ability to cope with transients.
None events were evaluated over the last two years. The conclusion reached was that there were no equipment performance problems identified which presented a significant impact on operating performance. This evaluation is documented in the February 18,1992 CECO FinalInvestigation Report (GCT 92 000).
V.
Provide to NRC Region til a documented evaluation of the above issues including corrective actions you have taken or plan to take.
SIAIV.S A copy of the CECO Investigation Report has been provided to the NRC Senior Resident inspector. Questions on the report can be directed to Mr. G.C. Tietz, Technical Superintendent, Quad Cities Station, (309) 654 2241 Ext. 2214.
ZNLD/1644/3
ATTACHMENT B BESPONSE TO AIT INVESTIGAT!ON INSPECTION. REPORT 254/92007 The AIT Reporildentified four concerns to be addressed in conjunction with the CAL response. CECO has reviewed these concerns and provides the following response:
MuMipio equipment failures raised concoms about the plant maintenanco program, A.
Concerns about practice of periodically operating with a large number of instruments with off normal indication (ONI) tags.
Quad Cities Response:
Quad Cities station has replaced or repaired defective components in the Main Steam Line Flow Indication instrument loops to remove ONI's prior to Unit 1 start up and will complete repairs and/or replacements on Unit 2 prior to its start up. By May 31,1992, the station will evaluate the ONI system including prioritization and resolution.
B.
Lack of preventive maintenance on the electromatic relief valves (ERV).
Quad Cities Hosponse:
The station will enhance ERV maintenance arocedures to include acceptance criteria for resistance across the shorting bar, a per odic inspection of the actuator parts, and lubrication of the actuator parts which exhibit wear. This is scheduled to be accomplished by October 1,1992, prior to the Unit i refuel outage.
The above preventative maintenance actions have been performed on the Unit 2 ERVs.
The station has also inspected and over-hauled worn paris within the actuator prior to start up of Unit 1.
By August 30,1992 the station will evaluate brass parts for possible material replacements.
ZNLD/1644/4
ATIACHMENT D 13ESEONSE.TO AIT INVESTIGATION IB 254/92007 (continued)
C.
Inadequate control of maintenance on the stop valve in the high pressure coolant injection (HPCI) system which was inoperable during this event.
Quad Cities Response:
The current Work Control Process provides controls which reasonably could have precluded this failure. The station and Engineering and Construction (ENC), will evaluate the Work Control Process and it's implementation to assure that acceptance criteria is provided. This is scheduled to be accomplished by May 31, 1992. Also, the station is performin0 random reviews of ENC Unit 2 work packages to verify that appropriate acceptance criteria is included. Results to date have found no unacceptable ENC work packages. These reviews are based on Maintenance judgment, experience, and good mechanical practices.
Additional. Station. Actions During the station investigation, the team evaluated equipment failures during the scram, in conjunction with four previous events and nine scrams which occurred i
in the last two years, for the effect of equipment failures on the ability of the operators to perform their required actions in response to an emergency s tuation. In all cases evalualed, the equipment problems did contribute minor distractions to operators; however, the equipment failures did not hamper the operators ability to respond to the event.
By May 30,1992, the station will evaluate its pre start-up On Site Review (OSR) process to assure that critical equipment f ailures are sufficiently investigated prior to start up from outa9es and restart from scrams in order to prevent repeat failures.
For equipment failures that occurred that have not been addressed by this report, the following actions have been taken:
A.
RFP High Level Trip Switches:
1.
By June 30,1992, the station will evaluate the replacement of the switches with state of the art technology.
2.
By September 10,1992, the station will calibrate the Yarway RFP high leve trip switches on a quarterly basis as opposed to the current scnedule of every refuel outage.
1 i
ZNLD/1644/5
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ATTACHMENLB BESEONSE.TQ AILINVESTIGATION IR 254/9200Z (continued) 8.
Main Steam Line High Flow instrumentation:
1.
Because the actual cause of the sciam could not be determined, the following measures will be taken to ascertain the root cause:
a.
The station installed instrument test equipment on the hydraulic lines and the electronics prior to start up of Unit 1.
b.
By May 30,1992, the station will evaluate replacing the Main Steam Line flow dp switches with analog trip instrumentation.
c.
The station wired the precurset Group 1 isolation computer points to the Sequence of Events tocorder prior to start up of Unit 1 and will wire Unit 2 prior to its start up.
ZNLD/1644/6
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