ML20045D774

LER 93-006-00:on 930520,inadequately Secured Separation Barrier Identified That Could Affect Control Switches for safety-related Equipment on Main Control Board.Caused by Human Error.Placard Posted to Restrict area.W/930618 Ltr

ML20045D774
Person / Time
Site:	Crystal River
Issue date:	06/18/1993
From:	Boldt G, Stephenson W FLORIDA POWER CORP.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
3F0693-14, 3F693-14, LER-93-006, LER-93-6, NUDOCS 9306300041
Download: ML20045D774 (5)

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Florida-Power CORPOHAY'ON crystal River unit 3 Docket No. s0-302 June 18, 1993 3F0693-14 U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, D. C. 20555

Subject:

Licensee Event Report (LER) 93-06

Dear Sir:

Enclosed is Licensee Event Report (LER) 93-06 which is submitted in accordance with 10 CFR 50.73.

Sincerely, f4 bW G. L. Boldt Vice President Nuclear Production EEF: mag Enclosure xc: Regional Administrator, Region II Project Manager, NRR Senior Resident Inspector

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9306300041 930618

( I 1 PDR ADOCK 05000302 i S PDR A Florida Progress Company

NRc roiw 3ss u.a. Nic. EAR REOULATORY COMM!SSION APPROYED OMB NO. 3160-0104

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OF MANAGEMENT AND 2"="d#l"ab20W BUDGET, WASHINGTON DC 4".T 20603 J F AC:LTTY 8MME(1) DOCKET MLAABER (2) FAGE (3)

CRYSTAL RIVER UNIT 3 (CR-3) 0l 5l 0l 0l 0] 3] 0l 2 1 lOFl 0 l 4 1TTL1 (4)

Inadequate Modification Design Results in Degraded Selsrnic Capability and a Condition Outside the Design Basis EVENT DATE (5) LER NUMBER (6) KPORT DATE (7) UTHER FACILITES NVOLVED(B)

SEQUENTIAL REVIS40N F ACILITV NAMES DOCKET NUMBER (S)

MONTH DAY YEAR YEAR NUMBER NUMBER MONTH DAY YEAR N/A 0l5l0l0l0l l l 0l5 2 l0 9 3 9l3 -

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CPfRATING THIS KPORT IS SUDurrTED PUFeuANT TO THE KOtRKMENTS OF 10 CFR 5: scHEcar ONE OR acatt OF THE Fouowws) (11) 20.402(b) 20.406(c) 60.73(aX2Xiv) 73.71(b)

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LICENSEE CONTACT FOR THIS LER(12)

NAME TELEPHONE NUMBER Ar4A CODE W. A. Stephenson, Nuclear Safety Supervisor 9l 0 l 4 7] i j 5 j- l 6l 4 ] 8 l 6 COMPLETE ONE LINE FOR EACH COMPONENT FAILURE IN THIS KPORT (13)

CAUSE SYSTEM COMPONENT MANUFAC- KPORTABLE  : CAUSE SYSTEM COMPONENT MANUFAC- REPORTABLE ; s TURER TO NPRDS TURER TO NPRDS Pu I I I I I I I -

1 I I I I I I I I I I I I I I I I I I I I SUPPLEMENTAL KPORT EXPECTED (14) EXPECTED MONTH DAY YEAR t SUBMISSK)N

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At 1707 on May 20, 1993, Crystal River Unit 3 (CR-3) was in Mode 1 (POWER OPERATION) at 100% Rated Thermal Power producing 873 Megawatts. While performing a field walkdown of separation barriers, an inadequately secured separation barrier (an open bo.. v approximately five inches by six inches) was identified that could affect control switches for certain safety equipment on t the main control board under certain seismic conditions. The equipment affected is the control switches used to throttle High Pressure Injection (HPI) flow via the HPI injection valves and their indicating lights. Adjacent control switches for the Low Pressure Injection (LPI) valves are also affected. This condition was caused by inadequate design of a plant modification. In 1990, a plant modification replaced the flow indicators directly above the separation barrier which removed the support for the barrier. A placard has been posted to restrict access to the area of the separation barriers affected. Florida Power Corporation is pursuing a plant modification to provide a secured separation barrier. Current design requirements prevent this problem from recurring.

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NFC Form 380 (6-89)

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EVENT DESCRIPTION:

At 1707 on May 20, 1993, Crystal River Unit 3 (CR-3) was in Mode 1 (POWER -

OPERATION) at 100% Rated Thermal Power producing 873 Megawatts. While performing a field walkdown of separation barriers, an inadequately secured separation barrier (see Figure 1) was identified that could affect control switches for certain safety equipment on the main control board [MCBD] under certain seismic conditions. The equipment affected is the control switches [HS] used to throttle High Pressure Injection (HPI)[BQ] flow via the HPI injection valves, MUV-23 and.24 and MUV-25 and 26 [BQ,INV] and their indicating lights [BQ,IL]. Adjacent control switches for the Low Pressure Injection (LPI) [BP] valves, DHV-5 and 6, [BP,INV) are also affected.

This condition was evaluated to determine if it affected the operability of the control switches. It was concluded that it did not. This is considered a condition outside the design basis and is reported in accordance with 10CFR50.73(a)(2)(ii)(B).

CAUSE:

This condition is considered to be the result of human error in the design of a ,

plant modification. In 1990, a modification replaced the flow indicators [BQ,FI]

directly above the separation barrier. The old flow indicators had a mounting screw which also secured the barrier. The new flow indicators are of a different design and did not have a similar mounting mechanism. This left the separation barrier inadequately secured. Due to insufficient research for the new design, .

other provisions for securing the barrier were not addressed. Additionally, the barrier and mounting configuration were not correctly identified in the original modification package that installed the barrier. This contributed to the omission.

EVENT EVALUATION:

The two separation barriers around switches for MUV-23 and 24 and switches for MUV-25 and 26 are not mounted to a stable structure and are being supported by flexible conduit to the control switches. Control switches for DHV-5 and DHV-6 are outside and immediately adjacent to the barriers. Each of the two barriers is an open box about 5 inches by 6 inches and is constructed of metal covered with asbestos. Its ,

purpose is to separate the valves from local energized equipment to prevent damage from heat or sparks.

The Engineered Safeguards portion of the main control board is required to conform to seismic criteria of IEEE Standard 344-1971. In accordance with the CR-3 design basis, this type of barrier must be designed such that movement of the barrier is precluded from interfering with any safety function.

Mft0 Form Se6A (6-49)

FUtM 3 sea U.S. NU2E.AR FIGULATC3Y COMM M APPROVED OMO NO. 3150-0104

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FMAHY HAME (1) DOMET NUMBER (2) LER HUMBER(e) PAGE (3)

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NUMBER NUMBER CRYSTAL RIVER UNIT 3 (CR-3) 0l $l 0l 0l 0l 3l 0l 2 9l3 -

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0l0 0 l 3 lOFl 0 l 4 TEXT ,, - . , - u , - . .<m Currently, the barrier does not interfere with wiring or control switch operation since the barrier is stationary. Movement of the barrier, due to personnel contact or a seismic event, could dislodge the barrier, potentially damaging or otherwise impeding the operation of the switch. This may cause a loss of the valve position indication or prevent the valves from performing their safety function. Due to the extremely low seismic nature of Florida, the dislodging of the barrier by a natural event is not a significant concern.

The HPI and LPI injection valves are required to mitigate numerous accidents analyzed in the FSAR, principally, Loss of Coolant Accidents (LOCAs). Loss of more than one HPI or LPI injection valve can lead to inadeoJate Cooling to the core during certain LOCAs.

CORRECTIVE ACTION:

A placard has been posted to restrict access to the area of the separation barriers affected. Florida Power Corporation is pursuing a plant modification to provide a secured separation barrier. Current design procedures, which stress attention to such detail, prevent recurrence of this error.

PREVIOUS SIMILAR EVENTS:

No previous similar events involving an inadequately secured separation barrier.

have been reported.

NRC Form 306A (6-89)

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