IR 05000295/1986023

Safety Insp Repts 50-295/86-23 & 50-304/86-22 on 860923- 1014.Violations Noted:Failure to Follow Procedure 2S-MS-25 Re Impulse Pressure to Electrohydraulic Control Transmitter

ML20215N927
Person / Time
Site:	Zion  File:ZionSolutions icon.png
Issue date:	11/04/1986
From:	Falevits Z, Muffett J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
To:
Shared Package
ML20215N912	List: IR 05000295/1986023 ML20215N911 ML20215N916
References
50-295-86-23, 50-304-86-22, NUDOCS 8611100082
Download: ML20215N927 (7)

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U.S. NUCLEAR REGULATORY COMMISSION REGION III-Reports No. 50-295/86023(DRS); 50-304/86022(DRS)

Docket Nos. 50-295; 50-304 Licenses No. DPR-39; DPR-48

, Licensee: Commonwealth Edison Company Post Office Box 767-Chicago, IL 60690 Facility Name: Zion. Nuclear Power Station, Units 1 and 2

. Inspection At: Zion Site, Zion, IL

- Inspection Conducted: S tember 23 through October 14, 1986 f. 51816 Inspector:

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Z. Falevits /0/27/h Date

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Approved By: J. W. Muffett, Chief "

Plant Systems Section Date Inspection Summary Inspection on September 23 through October 14, 1986 (Reports No. 50-295/86023(DRS);

50-304/86022(DRS))

Areas Inspected: Special unannounced safety. inspection conducted to followup on two Unit 2 events as follows (1) Reactor trip due to a transmitter valving error and (2) Second level degraded voltage actuation and failure of diesel generator 0 to come up to speed and voltage (30703B, 93702).

Results: Of the areas inspected, one violation was identified, failure to follow procedure or inadequate procedures - Paragraphs 2.a and ,

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7s DETAILS 1. Persons Contacted Commonwealth Edison Company (CECO) -

• E. Furest, Superintendent, Operations

• T. A. Rieck, Superintendent, Services

• • /*G. Far.ning, Engineer, Technical Staff

• B. Coscarano, Supervisor, Technical Staff

• J. Winston, Engineer, Quality Control

• J. Rohde, Group Leader, Technical Staff

• C. J. Schultz, Administrator, Regulatory Assurance W. Stone, Engineer, Quality Control

• R. Johnson, Supervisor, Maintenance USNRC M. M. Holzmer, Senior Resident Inspector, Zion L. E. Kanter, Resident Inspector, Zion

• Indicates those attending the exit meeting on September 24, 1986.

• • Person contacted during telephone communication on October 14, 198 The inspector also contacted and interviewed other licensee personnel during this inspectio . Review of the September 20 and 21, 1986, Unit 2 Events The purpose of this inspecti3n was'to' review the available facts relative to (1) The reactor trip on Septemoer 20, 1986, and (2) The secondary level bus degraded voltage and the failure of diesel generator to come up to speed and voltage on September 21, 198 Review of the September 20, 1986, Unit 2 Reactor Trip Due to a Transmitter Valving Error (1) On September 20, 1986, following the replacement of turbine pressure transmitter 2PT-MS024, the generator was synchronized to the grid and approximately 'two minutas later generator load increased to about 200 MWE without operator action. This occurred due to a failure in a logic card circuitry for the 8 feedwater regulating valve bypass valve. Unit 2 reactor tripped from approximately 20% reactor power on steam flow feed flow mismatch coincident with steam generator level less than 25%.

Investigation of this event indicted that the EHC transient was due to a valving error whereby the instrument mechanic, after replacing turbine impulse pressure transmitter 2PT-MS24,

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inadvertently opened the test connection isolation valve rather than~the isolation valve as r_equired by system design. This'

resulted in 2PT-MS24 being isolated from the system and unable

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to transmit the impulse pressure input into the EHC system as

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designed. This eventually contributed to the feed flow stea flow error signal which caused a reactor. tri The inspector reviewed the applicable procedures and documents

, and conducted a field visual inspection of the associated-valves-and transmitter. The inspector noted that transmi.tter 2PT-MS24 is classified as B0P (non safety-related), therefore, not requiring a second post installation verification check as is required on safety related transmitters. Neither was ~ a post installation system functional test required to determine if

the installed transmitter functioned in the loop as designed.

In addition, loop test procedure 2S-MS-25 dated October 22,

.1985 did not provide the instrument r:echanic with detailed

instructions as to which loop valves need to be opened. It contained the general statement " Transmitter valved in," while-the procedure for a comparable safety related transmitter (for-

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example IP-505T) required the instrument mechanic's initials for_ specific steps when. valving in a safety related transmitter, j such as:

Sensing line tubing in place.

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Test connection isolation valve shu *

Isolation valve ope In addition, a second independent verification is required for a safety-related application.

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The inspector noted that a contributing factor to the valving-error was the fact that the -instrument mechanic apparently

- acted on " skill of craft" impulse and did not pay attention to details.

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The inspector expressed his concern to the licensee, that' ~

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although transmitter 2PT-MS24 is classified as 80P (non '

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safety), failure of this device contributed to the reactor

' trip. ; Technical Specificatio.. (TS) 6.2.A.1 requires that 1 " written procedures including applicable check of lists covering instrumentation operation which could have an effect on the safety of the facility shall be prepared,

! implemented, and maintained." Failure to follow i Procedure 2S-MS-25 and include specific check off lists j in the procedure is an example of a violation of TS 6.2.A.1

(295/86023-01(DRS);304/86022-01(DRS)).

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' (2) In July 1986, the Zion senior resident inspector observed that a caution tag was placed in the Unit 2 Control Room to alert f the operator to the fact that when the main generator output i breaker is closed, the IVP for the Governor Valve (GV) load

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jumped to 60 MWE and above rather that to 30 MWE as require During this event, a similar situation occurred where the load jumped to 200 MWE after the main generator output breaker was close This is considered to be an open item pending licensee corrective action and NRC review (304/86022-02(DRS)).

b. Review of the September 21,19_86; U_ nit 2_, Second Level Degraded

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Vol Tol_ tag _e_ an_d FailuWiif~ Diesel Generator to come up'Yo Weed ~Eid tage On September 21,1986, bus 247 experienced a degraded voltage condition. The second level undervoltage protection system responded and functioned as designed up to the point when diesel generator 0 was called for to. come up to speed and voltage (usually withintenseconds). Prior to reaching it's normal operating speed and voltage the diesel tripped (within approximately three seconds).

Investigation of this event indicated that the engine trip occurred due to a spike in the start and engine control circuitry, as delineated on schematic diagram 22E-0-4831. During engine start, speed relay 14 RX sensed the speed of 225 rpm thereby deenergizing the start air solenoids. At which time a spike occurred causing chattering of the engine start circuit control relays. This affected the engine start sequence and caused the engine to tri The licensee has experienced relay chattering problems in the diesel manual start circuitry in the past. This occurred only during a manual start because there is no " seal-in" circuit in the manual portion of the DG start circuit. This problem did not occur in the past on a Safety Injection signal or an undervoltage signal to the diesel start circuitry due to the fact that these signals are " sealed in." On manual start of the diesels the manual start switch must be held closed during the first ten seconds to allow the engine to come up to full speed and voltage and to prevent engine trip due to relays chattering during the first ten seconds. A caution statement was incorporated into Procedure PT-11, Revision 14, dated December 1984 warning the operators to assure that the manual switch is held in start position during the first 10 seconds of engine start. Further review of this issue' indicated that Modification M22-0-84-32 was issued on February 19, 1985 to add spike suppression devices to the diesel control circuitry in order to eliminate the relay chattering problem. As of the date of this inspection, the licensee had incorporated this modification on diesel IB circuitry only, test of this circuitry has not been completed yet. The licensee indicated that due to other priority work this modification could not have been implemented sooner, that during the present outage this modifica-tion will be incorporated into the circuitry of all five diesel generator ,

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e The inspector reviewed the documentation associated with this degraded voltage event. The following documents were reviewed:

• Operating Procedure AOP-21 dated December 30, 1985

• Annunciator Response Procedure "4 kv' Bus 247 Voltag Degraded."

• Annunciator Response Procedure " Bus 247 Undervoltage."

• Reactor Trip Response Procedure ES-0.1 dated December 27, 198 * Technical Specification of undervoltage protection Tables 3.4-1, 3.4-2 and 4.4- * Sequence of Events Report for Zion 2 dated September 21 and 22, 198 * ~ Shift Engineer / Shift Foreman Station Log dated September 21, 198 * Modification M22-0-84-32 dated May 9, 198 * Grid Voltage chart for September 21, 198 * Diesel start schematic diagram 22E-0-4831, Revision * Secondary' Level Undervoltage schematic diagram 22E-2-4840, Page AP27, Revision L and AP68, Revision * Diesel Generator 0 Schematic diag-ams 22E-2-4840, Page'AP25A, Revision B, Page DG7, Revision * Reactor Protection - Accident and Safe Shutdown Schematic diagram 22E-2-4840, Page RP1, Revision L and Page RP19, Revision N * Main Feed Breaker ESS Bus 247 Schematic Diagram 22E-2-4840, Page AP23, Revision * Reserve Feed Breaker ESS Bus 247 Schematic Diagram 22E-2-4840, Page AP24, Revision During the event actual voltage was observed to be between 3950 and 4000 volts (4160 volts nominal) which was above the setpoint of the second level undervoltage relays of 3846 1 2% Volt The second level undervoltage circuitry is designed so that when bus voltage decreases to less than 3846 1 2% Volts for longer than eight seconds it automatically activates the second level of undervoltage protection 5 minute timer. After approximately five

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O minutes, if the condition persists, it activates the remaining undervoltage circuitry and a safe shutdown sequence occur The five minute time delay is given to allow the operators to respond to the degraded voltage condition before the automatic actions occu During this event, it appears that degraded. voltage Procedure A0P-21, which describes the immediate actions required when a degraded voltage condition exists on a 4kv ESF bus, was lengthy and out of logical sequence.when applied to the actual event conditions. For example, the second step of immediate actions (Step 5.2) required that the operator notify System Load Dispatcher of the immediate need to increase grid voltage to clear the degraded voltage condition. The operator'in an attempt to contact the load dispatcher, exhausted the allowed five minutes without being able to complete the rest of the procedures, this permitted the automatic function to occu Discussions with training personnel indicated that minimal training was given to the operators regarding Procedure A0P-21; the only present training requirement is to' read the procedure. The second level degraded voltage circuitry has not been incorporated into the simulator yet. This does not allow for this condition to be simulated during simulator trainin On October 14, 1986, the licensee's engineer in a telephone conver-sation with the inspector stated that their ongoing investigation into the event indicates that apparently the degraded voltage existed in the system for approximately five minutes, and that it cleared at the same time the loads were automatically shedded off the bus (the same time the five minute time limit expired). The voltage came back up to nominal voltage, resetting the automatic circuitr The licensee is still investigating this event, results of this investigation will be documented in a LE Zion FSAR Section 7.2 states "All features of the protection systems which actuate a reactor trip and engineered safety features action are designed and/or built . . and conforms to the intent of the criteria specified'in IEEE-279 of August 30, 1968."

"The protection system shall be so designed that once initiated, a protection system action shall go to completion. Return to operation shall require subsequent deliberate operator action."

This relates to the fact that the diesel started up but did not go to full power and voltage. The inspector informed the licensee his concerns as follows:

(1) The rolay chattering problem in the diesel control circuitry was known to the licensee for an extended period of time without the licensee taking prompt corrective action to correct i (2) Diesel generation "0" did not come up to full speed and power as required by design because of the chattering proble . . . . - _ .

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s (3) Operators did not receive formal training (simulator, classroom)

in responding to a degraded voltage conditio (4) Procedure was not appropriately written for the operator to follow within the allowed 5 minutes before automatic. action was initiated. Also the-operator needed to go through the ar.nunciator response sheet-before the procedure. This item is considered unresolved.pending licensee final investigation and corrective action and NRC review (295/86023-02(DRS)

304/86022-03(DRS)). On September 22, 1986, an Operational Analysis Department (OAD)

test engineer while investigating the degraded voltage problem, had opened a knife switch on 480V breaker 2474 circuitry. This prevented the auto reclosing of this breaker as required by. design after bus 247 is stripped.- This problem was' subsequently identified when Section 7 of test PT-10 was performed by the operators.. The knife switch was closed and the breaker reclose The inspector reviewed Work Request Z53392. dated September 21, 1986, and 0AD Relay Testing and Instrument Calibration Procedure ZAP 3-52-2 which.were used by the OAD engineer during the test. No requirement was available for review to control the opening and closing of knife switches. Technical Specification-(TS) 6.2.A.1 requires that written procedures including applicable checkoff lists covering surveillances, tests and experiments shall be prepared, implemented, and maintaine Failure to include requiremants to control the opening and closing of knife switches is considered an example of a violation of TS 6.2.A.1 (295/86023-03(DRS) 304/86022-04(DRS)). Open Items Open items are matters which have been discussed with the licensee, which will be reviewed further by the inspector, and which involves some action-on the part of the NRC~or licensee.or both. Open items disclosed during this inspection are discussed in Paragraph 2.t(2). Unresolved Items An unresolved item is a matter about which more information is required in order to ascertain whether it is an acceptable item,- an open item, a deviation, or a violation. An unresolved item disclosed during this inspection is discussed in Paragraph . Exit Interview The Region III inspector met with licensee representatives (denoted under l Paragraph 1) at the conclusion of the inspection on September 24, 198 l The inspectors summarized the purpose and findings of the inspectio l

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The licensee acknowledged this information. The inspector also discussed the likely informational content of the inspection report with regard to documents or processes reviewed by the inspector during the inspectio The licensee did not identify any such documents / processes as proprietar !

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