05000336/LER-1993-019

LER 93-019-00:on 930812,reactor Trip Occurred Due to Low SG Level.Conducted Shift Briefing of Event to Operating Shift While Assuming Watch.Briefing Included Listed Requirements for Subsequent Specific start-up.W/930910 Ltr

ML20057A978
Person / Time
Site:	Millstone
Issue date:	09/10/1993
From:	Scace S, Temple W NORTHEAST NUCLEAR ENERGY CO., NORTHEAST UTILITIES
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-93-019, LER-93-19, MP-93-718, NUDOCS 9309170019
Download: ML20057A978 (4)

LER-2093-019,

Event date:
Report date:
3362093019R00 - NRC Website

text

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U.S. Nuclear Reculatorv Commission Document Contr'ol Dess l Washington, D.C. 20555 l

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Reference:

Facility Operating License No. DPR-65 Docket No. 50-336 Licensee Event Report 93-019-00 Gentlemen:

This letter forwards Licensee Event Repon 93-019-00 required to be submitted within thirty (36) days pursuant to 10CFR50.73(a)(2)(iv). Specifically, a reactor trip occurred due to low steam generator water level.

Very truly yours, NORTHEAST NUCLEAR ENERGY COMPANY e

lh (W Step en E. Scace Vice President - Millstone Station SES'SS:ljs

Attachment:

LER 93-019-00 cc: T. T. Martin, Region 1 Administrator P. D. Swetland. Senior Resident Inspector, Millstone Unit Nos.1, 2 and 3 G. S. Vissing. NRC Project Manager, Millstone Unit No. 2 160022 fp l

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On August 12. l'L3. the p: ant was operatmg m Mode 2. At 13:M a reactor inp occurred due to low Steam l Generata (5Gi leve! Approximatch one hour pnor to the inp the plant had entered mode 2 (reactor entical) and SG !cseis were bemp riamtamed by one auxthar) feedwater pump. Reactor power had just been increased to 2"c and preparations v ere bemg made to start a main feedwater pump and bepn the turbme warmmg Procen. Fonowing the reaant inp Emergency Operatmp Procedure EOP 2525. Standard Post Trip Acuons, was per k rmed Al! safet) related equipment responded as expected, and the urut v.as placed m a stable condmon.

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1 Dr'erimum of Es ent On August 12,19'3. the plant was operaunc m .\1 ode 2. At 13:44 a reactor trip occurred due to low Steam Generator (SG) les e! Approximately one hou: prior to the tnp the Plant had entered mode 2 t reactor cnucah and SG les els were t'emp mamiatned bs one auxihary feedwater pump. Reactor power had Just been mcreased to 2r and preparauons were bemy made to start a main feedwater pump and begm the turbme warming process. Collowmg the reactor tnp Emergency Operaung Procedure EOP 2525.

3 hiandard Post Tnp Acuons. was performed. All safety related equ:pment responded as expected, and l the unn was placed m a stable condman. l I

, 11. Cause of Event '

The root cause of ths esent was operator mattention to Steam Generator cesel during plant transient condiuons As power levels were mcreased to M no adlustments were made to increase feedwater j flowrates for a 20-mmute ume pened. T)us caused SG leselv to decrease over this time penod. A SG level denauon alarm was ininated but apparentir not noticed by the control board operator. A contnbuung cause of this esent was the control rooms' tesponse to a high seruce water flow condinon on  ;

one of the reactor buildmg closed coolmg water heat exchangers md a cychng condenser steam dump vah e. When the low 5G lesel alarm was recened. a second auxihary feedwater pump was started. but the addiuon of cold auxthar3 feedwater caused a further SG water level decrease due to " shrink." with i the fmal result bemg the reactor tnp on low SG water level.

Ill. Anah + of Esent This LER is submitted m accordance with 10CFR50.73(alf 2)(iv), any event or condmon that results in a ,

manual or auwmaut actuauon of an3 engineered safety feature (ESF). Includmg the reactor protection j

, system (RPS).

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The safet3 consequences of this esent are mmimal smce the plant safett equipment functioned as  !

expeaed Followmg the reactor tnp, Emergency Operating Procedure EOP 2525, Standard Post Trip I Actions, was followed. All p! ant parameters responded as expected. Upon completion of Standard Post Tnp Actions, EOP 2525, Reactor Tnp Recovery, was implemented. All Safety Function Status Checks w ere performeci wahout note.

1 l\1 Correctn e Acticr; ,

i Temporary shon term conectne action was a shift briefmg of the event to each operating shif t as they ]

assumed the watch. This bnef mcluded the followmg regturements for the subsequent specific start-up. l l

1) The Supervsmg Comrol Operator (SCO) shall be nouhed of all alarms. l l

D The SCO' Secondary Plant Operator (SPO) will trend all SG levels on the control room display m omtor .

3) One beensed operator has been dedicated to SG level control.

Long term correcuve actions mclude:

A renew of the event has been completed with all Operations Personnel at shift bnefmps.

A formal Operations Department communication standard has been issued that reinforces the need for .

feedback and accurate two way cnmmurucanon. This remforces the requirements that all changes in the l plant conditions and all vahd alarms shall be brought to the attention of the SCO.

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M4 stone Nuciear Power Stat:On Une 2 05000336 93 - 019 - 00 03 OF 03 TExi e ,e u s, ., . ewe: a w ,==>es e Nac =w - seeA um The Operations procedure for reactor start-ur (OP 2202) has been revised to clanfy the transition bem een reactor start-up and piant start-up. The piant start-up procedure (OP 2203) has been reused to add a caution note to prompt the add:non of feeduter flow to rnainiam SG lesels af ter reactor power r increased ahose the pomt of addmp heat.

An -saluanon of the SG low lesel and Reactor Protecuan System (RPS) pretrm values foi low SG level has been inmated. Thn evaluanon will deternune if changes to the alarm setpomis are appropnate.

Tms esen: u tll be scheduled f or renew by licensed operators as part of hcensed operator requahhcation traming V. Addmenn! Information There were no :a: led componems.

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