ML19263C042

LER 78-127/03L-0 on 781230:asymmetric Rod Indication Was Received for Control Rod 4 of Group 5;unit Was in Mode 2 & Absolute Position Indicator for Rod 4 Was Inoperable.Caused by Dirty Module Contacts

ML19263C042
Person / Time
Site:	Davis Besse
Issue date:	01/26/1979
From:	Kovach S TOLEDO EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML19263C041	List: ML19263C040 ML19263C042
References
LER-78-127-03L, LER-78-127-3L, NUDOCS 7902020182
Download: ML19263C042 (2)

Text

U. S. NUCLEAR REGULATORY COMMISSION NRC FORM 366 (7 771

• LICENSEE EVENT REPORT CONTROL BLOCK: l l l l l l l (PLEASE PRINT OR TYPE ALL REQUIRED INFORMATION) l 6 o t l 0l Hl D Bl Sl 1 @l 0l 0] -l 0LsCENSE Pl Fl - 0l 3 l@[4_ LICENSE 0l NlNua.18EH 25 2F l1 l1 TYPE l1 l1JO lh! l 57 L' A T bd l@

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DATE EVENT DESCRIPTION AND FROB ABLE CONSEQUENCES h o 2 l On December 30, 1978, an asyr: metric rod indication was received for Control Rod 4 of l o 13_J l Group 5. T.S. 3.1.3.3 requires that all absolute position indicator (API) channels ]

o 4 be operable in Modes 1 and 2. The unit was in Mode 3 at the time of the occurrence. l o s l API for all other rods in Group 5 was operable during the period that the API for Rod l l o J s l l 4 of Group 5 was inoperable. Relative position indication for Rod 4 of Group 5 was l

l o 7 1 also operable. (NP-33-78-14 9) 1 0 8 l 80 CAUSE COYP. VALVE SYSTEM CAUSE SUSCODE SUBOODE CODE CODE SUBCOOE COP 3PCNENT CODE O 9 l Rl Blh Wh l E lh lI f3lN l S lT lR lU lh lE h [ Zj h 12 la 19 20 7 8 9 10 11 REVISION SEQUENTI AL OCCURRENCE REPORT CODE TYPE No.

REPORT N9 LER Ro DVENT YEAR O aEPOaf l7 l8 l l_) l1l2 7 l/l 10 l 3 l l Ll l-l 31 l 01 32 24 26 27 23 29 JJ

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d. S PLI MANU. AC URER TAKEF A T ON ON PLAP T THQ HO'RS J 22 S B IT FC !

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Ja 36 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS h l

i o l The ampli fier module was bench checked and re-installed. An asv: metric f ault alara i1 1 1did not reappear. It is suspected that the cause of the occurrence was dirty contactsi

,, 7 l on the module, and that its recOval and insertion caused enough abrasion to remove thel

, 3 dirt. Since there have been no previous cccurrences of inoperable APIS due to dirty l to monitor the problem will be taken.

11141 l contacts, no corrective action other than continuing 80 7 8 9 IS O RY DISCOVERY DESCRIPTION ST S  % POWER oTHER STATUS NA l i 5 l Gl@ l 0l 0l 0l@lNA l lAl@l

• 48nvirY Co'0 TE NT LOCATION oF RELEASE RELEASED OF RELE ASE AMOUNT OF ACTIVITY l

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1 6 8 9 h I Zl 10 11 NA 44 l

45 80 PERSONNEL EXPOSURES NJVBER TYPE DESCRIPTION I

i 7 1010 O l@l z l@l NA 80 PERSONNE L INJU IE3 NUVRER DESCRtPTION l

ITTTl 010 l Ol@l12NA 80 7 8 9 11 LOSS OF OR DAVAGE To FACILITY .

TYPE DE SCRIP TION l

7 i 9 8 9 lZlhl .0 NA NRC USE ONLY 80 PUBLICITY

• ISS 12 l o l l g!Dn" lel NA D E SC nip TION I IIII I i I i ! LLJa" l

'4 9 0 2 0 2 012f2_ san A. h a d PHONE:

DVR 78-195 NAME OF PREPARER

TOLEDO EDISON CO: PANY DAVIS-BESSE NUCLEAR POWER STATION U'!IT ONE '

SUPPLEMENTAL INFORMATION FOR LER NP-33-78-149 i

DATE OF OCCURRENCE: December 30, 1978 i

FACILITY: Davis-Besse Unit 1 IDENTIFICATION OF OCCURRENCE:

The Absolute Position Indication for Group 5, Rod 4 was inoperable Conditions Prior to Occurrence: The unit was in Mode 3, with Power (MWT) = 0, and Load (Gross MWE) = 0.

Description of Occurrence: At 0200 hours0.00231 days <br />0.0556 hours <br />3.306878e-4 weeks <br />7.61e-5 months <br /> on December 36, 1978, an asymmetric rod indication was received for Control Rod 4 of Group 5. Technical Specification 3.1.3.3 requires that all absolute position indicator (API) channels be operable and capable of determining control rod positions within + 6.5%. The unit was not

.placed in any Action Statement since the Technical Specification is applicable in Modes 1 and 2, and the unit was in Mode 3 at the time of the occurrence. This re-port is being submitted as documentation of a component f ailure.

Designation of Apnarent Cause of Occurrence: The cause of the occurrence was ini-tially suspected to have been a f aulty ACT. amplifier module. 1~he Lodule was bench checked, however, and no problems were found. The cause is now thought to have been dirty contacts on the module.

Analysis of Occurrence: There vas no danger to the health and safety of the public or to unit personnel. Absolute position indication for all other rods in Group 5 was operable during the period that the API for Rod 4 of Gir up 5 was inoperable.

Relative position indication for Rod 4 of Group 5, as well as for all other rods in this group, was also operable during this time.

Corrective Action: Under Work Request IC-3513, Instrument and Control personnel bench checked and re-installed the amplifier module. An asymmetric fault alarm did not reappear. It is suspected that the cause of the occurrence was dirty contacts on the module, and that its removal and insertion caused enough abrasion to remove the dirt.

Since there have been no ptcvious occurrences of inoperable APIS due to dirty con-tacts, no corrective action other than continuing to monitor this problem will be taken. Should this problem become repetitive, further investigation will be carried out.

Failure Data: There have been no previously reported similar occurrences.

LER #78-127