05000346/LER-1977-091-03, /03L-0:on 771107,containment Radiation Monitor RIS 2006 Spiked & Reset Twice Causing Safety Features Actuation Sys Incident Level 1 Trips.Caused by Design Error

/03L-0:on 771107,containment Radiation Monitor RIS 2006 Spiked & Reset Twice Causing Safety Features Actuation Sys Incident Level 1 Trips.Caused by Design Error

ML19329D290
Person / Time
Site:	Davis Besse
Issue date:	12/01/1977
From:	Nelson J TOLEDO EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML19329D287	List: 05000346/LER-1977-091, Forwards LER 77-091/03L-0 05000346/LER-1977-091-03, /03L-0:on 771107,containment Radiation Monitor RIS 2006 Spiked & Reset Twice Causing Safety Features Actuation Sys Incident Level 1 Trips.Caused by Design Error
References
LER-77-091-03L, LER-77-91-3L, NUDOCS 8002270855
Download: ML19329D290 (3)

LER-1977-091, /03L-0:on 771107,containment Radiation Monitor RIS 2006 Spiked & Reset Twice Causing Safety Features Actuation Sys Incident Level 1 Trips.Caused by Design Error

Event date:
Report date:
3461977091R03 - NRC Website

text

U. S. NUCLEAR Ht.GULA f un v GL. men.v.e NRC FCM 366 17 77I

CENSEE EVENT REPORT ONT' OL BLOCK: l l

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CON'T lotil 60 61 OCCKET *. UMBER

'ia L3 EVENT DATE 74 75 RE* ORT CATE 80 8

EVENT DEScalPTION AND PROBABLE CO.*ASECUENCES h On November. 7,.1977, Containment Radiation Monitor RIS 2006 spiked and was reset on I 1012 l l 70,3, ; - twoociasrions causing SFAS Incident Level l Trips at 0336 and 0615 hours0.00712 days <br />0.171 hours <br />0.00102 weeks <br />2.340075e-4 months <br />. This-l-

go,,p.l..placaA the _ station in;ths Action _S_tatement.of Technical. Specification (TS) 3.4.6.1 l

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1 o I s f -l each time ~_11200. hours. on November 8,1977, SFAS Chan=eic 3 Containment Radiation l

Fo is f I - Mon'itorms' canudl.ly.Aripoed wh-ich-put:-the station in. the Actionc Statement of-TS.

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m I o I 7 I [~ 3.3.2.L.. _.there was no. danger to the health and safety of the public or station

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DAVIS-EESSEUNITONENUCLEARPCWERSTATION

\\ j SUPPLEMENTAL INFORMATION FOR LER NP-33-77-91 DATE OF EVENT:

November 7, 197_7_ _.

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FACILITY: Davis-Besse Unit 1 IDENTIFICATTON OF OCCURRENCE:- - Saf ety Features Actuation System (SFAS) -Level 1 Trip due to High Radiation Irtp from Containment Radiation Monitor RIS 2006c Conditions 3.s.ior to Occurr.nce:, The plant was in Mode.1, with Power. (5'I) = 700

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and Load (MWE) < 240

- Description of Occurrence:

OrcNovember. 7,1977 at 0336 houts,.s Radiation }ionitor

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RIS "2006 sptked-giving 2 S. iS -15cident-Level-1 Trip. - STAS Channel 4 Contain=ent-Ju %

Radiatiott-war-declared ino_:rald e.and-manually tripped., prey,iouslypt 0130- hours (see. --u.

- NP 77-89); to give ::he o pat-of fcur-trip. - This.placedythe _ station -in the.

.s ActhStatement of Technic it Specification (TS) 3.4.&L-on _ Reactor..C.colant System Leakage Detection.

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At -0445-hotrrs, r he load was drgppeds tosl3-SeMWE...- RIS.2006 -fpil_ owed:. power reduc- :

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....3 O tion-and was res'et at 0503 :. curs..whfch removed the statiok rom-the ' Action State,

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,jmentofS3.4.6.1.

- At 06I5"If6ursf MIS 2006 sp.kedsancerippedeSFAS Channel-3-Containment Radiation.-.- _,..

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~sgairr whi~ch pre SFAS Level 1 Trip-and-placed the station irr the Action S::atement 6f TS~ -3.h6.I?" STAS-Channel 3 Containment Radiatiotr-.was resetat._0&lS hours when __.

RIS 2006-staitVd'eo read nor: nits ~nich-removedu:he station, f. rom. Act; ion Statement.

Plant' operation was reduced ':o: Mo.de 2. a.t 1245 hours0.0144 days <br />0.346 hours <br />0.00206 weeks <br />4.737225e-4 months <br /> _ foe work _ on RIS 2007 and

- --RIS' 200 6 ; -SFAS' Chatinel -3 Cc sesinment-Radiation-was =anually-tripped which placed --.. :_.

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- the' station i*-the Action Statement. of:TS 3.3.2.1-at 1200. hours on November 8,.

-- 1977"a'feerWFAS'-Channel 4-ContainmentaRadiation was-declared.. operable. _..

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Ues-is nation--of -Accarent Cause of-Occurrence: The apparent. cause was due-to-

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sdesign/fabricatior. error, specifically imprqger electrifil iioTalion' between detector (instrument) ground and..c.ouduit.( tation), ground _.

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" L ' - Analvsis-$f 4ceifrrence: Thenaivas.< no danger-:to-rhe health and safety.- of-. the publig_.; :

c or to station personnel. SFAS 4.evel -L-Incident-Tr.ip occurted as. the systen,isc.de e.

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-- = signed etr. -' There-was always three+SFAS -Containme_nt Radiatioq,Jfonicors.cperab,lan throughout the occurrence.

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DAVIS-BESSE UNIT ONE NUCLEAR POWER STATION dSUPPLEMENTAL INFORMATION FOR LER NP-33-77-91 PAGE 2 Cor~recTfve Action: Corrective action con:menced on November 8,1977 at 1200 hours0.0139 days <br />0.333 hours <br />0.00198 weeks <br />4.566e-4 months <br />.

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The problem was determined to be a grounding problem between the detectnr_ (instru-mene) and. station ground. Tho detector was then electrically isolated by removal of tih'e rocating bracket #903416 from within the detector containment housing-assem-

-- bly-(Victoreen Print #905194). This was done in conjunction with and approval from the vendor, Victoreen.

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- SFAS Channel 4 containment Rad 4ation was placed back in service on November 8, _

1977 at 1330 hours0.0154 days <br />0.369 hours <br />0.0022 weeks <br />5.06065e-4 months <br />, which removed the station from the Action Statement of TS 3.3.2.1.

This modification will be performed on all four SFAS Radiation Detectors per Facility Change Request 77-~462..

4 11ura? Data: One previous incident occur 1_ed,qn October 24.g l9.77 when a fault occurred between the Radiation Module in the Control Room.and the cabinet it was

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