ML18096B326

LER 93-004-00:on 930206,both Main Turbine first-stage Impulse Pressure Indication Channels Indicated False Readings.Caused by Inadequate Sensing Line Protection. Failed Heat Tracing Will Be repaired.W/930305 Ltr

ML18096B326
Person / Time
Site:	Salem
Issue date:	03/05/1993
From:	Pastva M, Vondra C Public Service Enterprise Group
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-93-004, LER-93-4, NUDOCS 9303110188
Download: ML18096B326 (6)

Text

e OPS~G Public Service Electric and Gas Company P.O. Box 236 Hancocks Bridge, New Jersey 08038 Salem Generating Station March 5, 1993 U.S. Nuclear*Regulatory Commission Document Control Desk Washington, DC 20555

Dear Sir:

SALEM GENERATING STATION LICENSE NO. DPR-75 DOCKET NO. 50-311 UNIT NO. 2 LICENSEE EVENT REPORT 93-004-00 This Licensee Event Report is being submitted pursuant to the requirements of the Code of Federal Regulations 10CFR

50. 73 (a) (2) (i) (B). This report is required to be issued within thirty (30) days of event discovery.

Sincerely yours, o;.~ A. Vondra General Manager -

Salem Operations MJP:pc Distribution 110032 The Energy People

}eJ} I I 9303110188 930305 95-2189 ( 1OM) 12-89 PDR ADOCK 05000311 S PDR

t NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION (6-89) - APPROVED OMB NO. 3150-0104 EXPIRES: 4/30/92 ESTIMATED BURDEN PER RESPONSE TO COMPLY WTH THIS INFORMATION COLLECTION REQUEST: 50.0 HRS. FORWARD LICENSEE EVENT REPORT (LER) COMMENTS REGARDING BURDEN ESTIMATE TO THE RECORDS AND REPORTS MANAGEMENT BRANCH (P-530), U.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON, DC 20555, AND TO THE PAPERWORK REDUCTION PROJECT (3150-0104). OFFICE OF MANAGEMENT AND BUDGET, WASHINGTON, DC 20503.

FACILITY NAME 111 DOCKET NUMBER 121 PAGE 13)

Salem Generating Station - Unit 2 TITLE 14) 0 I 5 I 0 I 0 I 0 13 I 11 l I 1 OF 0 ,s Tech Spec 3.0.3 Entry: Inoperability of Both Turbine First Stage Pressure Channels.

EVENT DATE 151 LEA NUMBER 161 REPORT DATE 171 OTHER FACILITIES INVOLVED 18)

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NAME TELEPHONE NUMBER AREA CODE M. J. Pastva, Jr. - LER Coordinator COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT 1131 MANUFAC- MANUFAC*

CAUSE SYSTEM COMPONENT SYSTEM COMPONENT TURER TUR ER 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 1141 MONTH DAY YEAR EXPECTED n YES (If Y*S. compl*to EXPECTED SUBMISSION DA TEI ABSTRACT (Limit to 1400 spaces, i.e.* approximately fifteen single-space typewrittsn Jines) (16) hzi NO SUBMISSION DATE (151 I I I At 2105 hours0.0244 days <br />0.585 hours <br />0.00348 weeks <br />8.009525e-4 months <br />, on 2/6/93, Tech. Spec. 3.0.3 was entered due to operation outside Tech. Spec. Table 3.3-3 Action 14. Both main turbine first stage impulse pressure indication channels (PT-505 and PT-506) were indicating false readings. PT-505 and PT-506 provide turbine power input for plant control during power operation. PT-505 was indicating downscale and PT-506 was indicating upscale. This was first observed via automatic rod insertion. Rod motion was stopped by placing rod control in manual. The PT-505 and PT-506 indications returned to normal within approximately one minute following a change in the building ventilation lineup which increased ambient air temperature around the sensing line. Satisfactory channel functional checks showed the instruments operable and at 2109 hours0.0244 days <br />0.586 hours <br />0.00349 weeks <br />8.024745e-4 months <br /> (same day), Tech. Spec. 3.0.3 was exited. The root cause of this event is equipment failure. Sensing line protection from cold environment conditions was found to not be adequate. When this event occurred, the outside ambient temperature was less than 20°F. Missing insulation from.the channels' transmitter sensing lines (which will be replaced) and the PT-506 heat trace had failed (which will be repaired) was identified. An Operations Department Night Order Book entry has been made to preclude chilling the PT-505 and PT-506 transmitter sensing lines. The administrative program for preparing Salem Station for Winter operation will be reviewed. Revisions will be incorporated as appropriate.

NRC Form 366 16-89)

LICENSEE EVENT REPORT (LER) TEXT CONTINUATION Salem Generating Station DOCKET NUMBER LER NUMBER PAGE Unit 2 5000311 93-004-00 2 of 5 PLANT AND SYSTEM IDENTIFICATION:

Westinghouse - Pressurized Water Reactor Energy Industry Identification system (EIIS) codes are identified in the text as {XX}

IDENTIFICATION OF OCCURRENCE:

Technical Specification 3.0.3 Entry: Inoperability of Both Turbine First Stage Pressure Channels Event Date: 2/6/93 Report Date: 3/5/93 This report was initiated by Incident Report No.93-112.

CONDITIONS PRIOR TO OCCURRENCE:

Mode 1 Reactor Power 100% - Unit Load 1160 MWe DESCRIPTION OF OCCURRENCE:

At 2105 hours0.0244 days <br />0.585 hours <br />0.00348 weeks <br />8.009525e-4 months <br />, on February 6, 1993 Technical Specification 3.0.3 was entered due to operation outside Technical Specification Table 3.3-3 Action 14. Both main turbine first stage impulse pressure indication channels (PT-505 and PT-506) were indicating false readings. PT-505 was indicating downscale and PT-506 was indicating upscale. PT-505 and PT-506 provide turbine power input for plant control during power operation.

This was first observed, at 2105 hours0.0244 days <br />0.585 hours <br />0.00348 weeks <br />8.009525e-4 months <br />, via automatic rod insertion.

Abnormal Operating Procedure, S2.0P-AB.ROD-0003(Q), "Continuous Rod Motion" was entered. Rod motion was stopped after placing rod control in the manual mode of operation and the affected control rods were withdrawn to prior position.

The PT-505 and PT-506 indications returned to normal within approximately one minute following a change in the building ventilation lineup which increased sensing line ambient air temperature. Satisfactory functional checks showed the channels operable and at 2109 hours0.0244 days <br />0.586 hours <br />0.00349 weeks <br />8.024745e-4 months <br /> (same day), Technical Specification 3.0.3 was exited.

In MODES 1, 2, and 3, Technical Specification Table 3.3-3 requires a minimum of one (1) OPERABLE main steam flow indicator. Technical Specification Table 3.3-3 Action 14 states:

LICENSEE EVENT REPORT (LER) TEXT CONTINUATION Salem Generating Station DOCKET NUMBER LER NUMBER PAGE Unit 2 5000311 93-004-00 3 of 5 DESCRIPTION OF OCCURRENCE: (cont'd)

"With the number of OPERABLE Channels one less than the Total Number of Channels, operation may proceed until performance of the next required CHANNEL FUNCTIONAL TEST, provided the inoperable channel is placed in the tripped condition within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />."

Technical Specification 3.0.3 states:

"When a Limiting Condition for Operation is not met except as provided in the associated ACTION requirements, within one hour action shall be initiated to place the unit in a MODE in which the specification does not apply by placing it, as applicable, in:

1. At least HOT STANDBY within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />,

2. At least HOT SHUTDOWN within the following 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />, and

3. At least COLD SHUTDOWN within the subsequent 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

Where corrective measures are completed that permit operation under the ACTION requirements, the ACTION may be taken in accordance with the specified time limits as measured from the time of failure to meet the Limiting Condition of Operation.

Exceptions to these requirements are stated in the individual specifications."

APPARENT CAUSE OF OCCURRENCE:

The root cause of this event is equipment failure. Sensing line protection from cold environment conditions was found to not be adequate. When this event occurred, the outside ambient temperature was less than 20°F. Investigation identified the following concerns:

PT-505 sensing line - Missing insulation from the entire length of the transmitter sensing line tray. Continuity checks showed the sensing line heat trace was functioning properly.

PT-506 Sensing Line - Burnt open primary and secondary heat trace wiring and controllers with a missing section of transmitter sensing line tray insulation.

It could not be determined how long the insulation has not been in place for either transmitter sensing line.

ANALYSIS OF OCCURRENCE:

Due to the entry into Technical Specification 3.0.3 this event is reportable to the Nuclear Regulatory Commission per Code of Federal Regulations 10CFR 50.73(a) (2) (i) (B).

This event did not affect the health and safety of the public. The PT-505 and PT-506 channels were inoperable for less than five (5)

LICENSEE EVENT REPORT (LER) TEXT CONTINUATION Salem Generating Station DOCKET NUMBER LER NUMBER PAGE Unit 2 5000311 93-004-00 4 of 5 ANALYSIS OF OCCURRENCE: (cont'd) minutes during which time their functions were not challenged. Also, the automatic trip functions and engineered safety features were available.

PT-505 and PT-506 are first-stage turbine pressure sensors which provide inputs for reactor control during power operation. PT-505 provides: input into the Steam Dump System for indication of Reactor Coolant System {AB} reference temperature; input into the Rod Control System {AA} for T v reference values; input into the main steamline flow se~p2int; provides the level setpoint for Steam Generator level control; provides reference main turbine power signal to the turbine electrohydraulic control system; provides input into permissive interlock P-13 which is used for development of the P-7 permissive (the permissive for blocking certain reactor trip functions above 10% power); provides input to P-2 (a permissive to place control rods in automatic operation, above 15% power, for control rod withdrawal); and input into AMSAC (Anticipated Transient Without Scram Mitigation System Actuation Circuitry)

• PT-506 provides input to arm the Steam Dump System in the event of load reject, provides input into the high main steamline flow setpoint, and input into AMSAC.

With PT-505 failing downscale and PT-506 failing upscale, if there was a required automatic actuation of the Steam Dump System due to a valid load rejection signal, the steam dump valves would not automatically open. The MS10 atmospheric relief valves would open at their setpoint of approximately 1037 psi to mitigate the pressure transient. Manual operation of the Steam Dump System valves would remain available. During inoperability of the PT-505 and PT-506 transmitters, automatic reactor trip functions on OTDT remained available and would have functioned in the event that a postulated load rejection went unabated.

As identified in the Description of Occurrence section, with PT-505 failing downscale, automatic control rod insertion began, per design. Rod motion was stopped by placing rod control in the manual mode of operation. Operations personnel had reacted quickly to the event thereby limiting rod movement. There was no observed power reduction.

CORRECTIVE ACTION:

Following this event, an Operations Department Night Order Book entry was made to ensure the Turbine Building ventilation system is aligned to preclude chilling the PT-505 and PT-506 instrument sensing lines.

The failed heat tracing will be repaired, and the missing sensing line insulation will be replaced.

LICENSEE EVENT REPORT (LER) TEXT CONTINUATION Salem Generating Station DOCKET NUMBER LER NUMBER PAGE Unit 2 5000311 93-004-00 5 of 5 CORRECTIVE ACTION: (cont'd)

The admin'istrative program for preparing Salem station for Winter operation will be reviewed. Revisions will be incorporated as appropriate.

System Engineering is continuing to assess why the PT-505 and PT-506 channels failed in opposite directions. Also, the Salem Unit 1 heat trace configuration will be evaluated.

Y8&4r

~G(g.eneral Manager -

{,/ Salem Operations MJP:pc SORC Mtg.93-021