IR 05000454/1996009

Discusses 970124 Meeting W/Util in Lisle,Ill Re Actions Related to Excessive Silt Buildup in ESW Cooling Tower Basins at Byron Station.Issue Discussed in Detail in Insp Repts 50-454/96-09 & 50-455/96-09

ML20147F359
Person / Time
Site:	Byron
Issue date:	03/13/1997
From:	Lanksbury R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
To:	Graesser K COMMONWEALTH EDISON CO.
References
NUDOCS 9703200316
Download: ML20147F359 (57)

Text

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l j ,j March 13, 1997 f6 - Ql

, Mr. l

Site Vice President l 1 Byron Station  !

l Commonwealth Edison' Company j

4450 N. German Church Road i

! Byron, IL 61010

i SUBJECT: BYRON PRE-DECISIONAL ENFORCEMENT CONFERENCE  ;

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l i

Dear Mr. Graesser:

i i This refers to the meeting conducted at the NRC Region ill Office in Lisle, Illinois on

! January 24,1997. The meeting was to discuss your actions related to the excessive silt

buildup in the essential service water cooling tower ba 'ns at the Byron station. This issue i is discussed in detail in inspection Reports (50-454/96009(DRP) and 455/96009(DRP)).

The topics discussed at the meeting included our findings and your related corrective

actions, both completed and planned.

i

! In accordance with Section 2.790 of the NRC's " Rules of Practice," Part 2, Title 10, Code l of Federal Regulations, a copy of this letter with Enclosures 1,2 and 3 will be placed in j the NRC's Public Document Room.

i l We appreciated your cooperation in this matter. If you have any questions regarding this meeting, please contact me at 630/829-9631.

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Sincerely, l

l /s/ R. D. LanKsbury

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Roger D. Lanksbury, Chief l Reactor Projects Branch 3 i Docket No. 50-454

' l Docket No. 50-455

Enclosures:

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1. Partial List of Attendees (

j 2. Licensee Presentation, Essential Service Water Issues l

3. Licensee Presentation, Summsry of Pre-decisional Enforcement Conference

Presentation I i

DOCUMENT NAME

A:\BYR-EMTG.LTR  :

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To receive a copy of this document, indicate in the box "C" = Copy without attach /enci l

"E" = Copy with attach /enci "N" = No copy I OFFICE Rlli ( Rlli tJ

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NAME Tongue /coC[ LanksburyM-

) DATE 3/ 0/97 3/LY97

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OFFICIAL RECOR D COPY I

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9703200316 970313 l PDR ADOCK 05000454 G PDR

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REGION III==

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AGENDA

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Opening Remarks !

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Overview K. Kofron

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Investigation Team R. Freidel

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Issues and l

Corrective Actions D. Wozniak

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Conclusions i  !

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OPENING REMARKS  :

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Essential Service Water event at l

Byron l - Corrective actions, which are l broad based and in-depth l

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After the initial discovery of the

! silting problem, the approach j we took and are continuing to

!

take is to make sure we have a

, conservative safety focus. We l

! need to assure you that

! uncompromising nuclear safety

is our absolute target.

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OPENING REMARKS

- Cont.

We are very disappointed by '

this event. Byron cornerstones .

have been:

- Not to c.efer maintenance

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- Promptly identify and resolve issues In this event, there are examples of not following these cornerstones.

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i-OPENING REMARKS j - cont.

Surveillances, Tech Spec or -

l Xon-Tech Spec, receive the l same level of review, rigor, and .

l prompt disposition.

l Equipment to meet its design basis.

We have recognized the

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violations as characterized in j the inspection report and concur l with your assessment.

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Do what is right regardless of l

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whether a surveillance is l Technical Specification or Non-l Technical Specification related. 5 i

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OVERVIEW

- On October 15,1996, a Pro alem Identification Form (PIF) was generatec. when t:1e Essential Service Water Cooling Tower ,

(SXCT) siltinspection surveillance did not aass acceptance criteria.

- An operability assessment was completec. and SXCT basin level was increased on 10/18/96.

- Management made a conscious decision to continue work on t:1e

. Unit 2 System Auxiliary Transformers and their associated ductwork, while continuing to investigate the Essential Service Water Cooling Towers. 6

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OVERVIEW - cont.

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During initial restoration

! activities, other issues were I ic entified: 1

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Fallen trash racks.

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l Trash rack bolting and level switch

! mounting corrosion.

l Error in Ultimate Heat Sink (UHS)

i calculation.  :

Foreign material exclusion (FME)

! concerns in and around the SXCT '

basin.

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OVERVIEW - cont.

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l - Basec. on the growing num aer of l

! issues ic.entified between l

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10/:.8/96 and 11/04/96, it was l recognized we were not being

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aromat and extensive enough with our corrective actions. This

. resulted in our escalating the event to a Level 2 investigation anc. commissioning the Investigation Team on 11/04/96.

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OVERVIEW - cont. '

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Accelerated restoration of UHS l

! Removed silt and debris from SXCT l basins.

Fixed trash racks and trash rack l bolting.

Inspected and removed silt from River Screen House (RSH).

Performed heat exchanger inspections.

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INVESTIGATION l TEAM i i

l l The investigation team was .

l divided into two organizations -

! the Working Group and the -

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Root Cause Team. l i

l - The charter of the Working Group

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was to remove silt from the SXCT and repair the trash racks.

- Tae caarter of the Root Cause Team was to identify the root ,

cause of two events anc. to !

provide corrective actions as appropriate.

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INVESTIGATION l TEAM - cont.

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Working Group .

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! - Monitored plant equipment during silt removal to assure equipment and j performance of the system were not !

l degraded.

l - As issues were identified, we I

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performed operability assessments.

! - Issued tower repair design details

! and resolved design documents l discrepancies.

j - Temporarily revised current j Essential Service Water Cooling l Tower inspection procedure,

! permanent revision is in-progress.

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INVESTIGATION

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l TEAM - cont.

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Root Cause Team '

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- Determined i:?the causes for I c.e..ayed compi.etion of i " Inspection ofRiver Screen j House (RSH) and Essential

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Service Water Cooling Tower" l

surveillance, cou c occur with j other surveillances.

- Reviewed ALL Essential Service i

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Water system Non-Teca Spec

! surveillances for connection with operability requirements, as well as for quality, content, meaningfulness of acceatance criteria, and notification to Shift Manager for failure of acceptance criteria. 12

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INVESTIGATION

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TEAM - cont.

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Root Cause Team - cont.

l - Investigated the review anc.

l cisposition process of older Work Requests.

- Reviewec. other Essential Service

Water system Work Requests, i

anc. determined if any actions l were rec uired.

l - Lookec. at design basis Inowlec.ge level of engineers relative to management expectations.

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INVESTIGATION l

i TEAM - cont.

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Scope Expanded

! - Design basis knowledge review of groups outsic.e engineering.

- Quality ofNon-Tech Spec surveillances on other systems.

- Source of c.e aris in the tower anc.

adequacy of FME practices.

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INVESTIGATION l

i TEAM - cont.

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Summary ofIssues Found

- Weak understanding of

. 1 l management exJectations j l Non-Tech Spec execution ,

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j Non-Tech Spec surveillance impact

on operability l Design Basis knowledge i

! - Proceduralinadec uacies

! Acceptance criteria (

Conflicting program requirements

Inadequate M&TE

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Lack of FME guidance

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!~ INVESTIGATION i-

TEAM - cont.

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! Summary ofIssues Found -

cont.

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- Work control process weakness Review of old Work Requests did not provide guidance for resolution Inadequate review Participation needed improvement

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ISSUES and l

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CORRECTIVE l

ACTIONS i -

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l Inadequate Acceptance Cr.i:eria i '

l Inadequate Test Control Excessive Silt Accumulation l

Degraded Trash Rack Grating l LFSAR Discrepancies on SX l Cooling Tower Design Features

Inadequate SX Makeup Calculation

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Inadequate Acceptance i

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Criteria i .

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Root Cause a

! - Poor engineering review.

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! Lack of a questioning attitude.

! - The original acceptance criteria

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were generated by an Architect l Engineer letter, dated May 17,

.990.

There was no clear basis for the acceptance criteria.

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ll Inadequate Acceptance i Criteria - cont.

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! Corrective Actions

- Engineering is performing l calculations to determine an adequate long-term acceptance criteria for Essentia Service Water Coo ing Tower silting.

(03/14/97)

- Review ALL Non-Tech Spec surveillance's that perform testing on safety-related equipment to ensure they: (07/30/97)

Provide clear, valid, and consistent acceptance criteria.

Acceptance criteria refers to design basis,if applicable.

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Engineering is re.ying less on

! outside engineering, and

! performing more in-house.

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l- Inadequate Test Control

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Root Cause l - An established practice 0:Pusing

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non-M&TE methods existec. due j

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to the visibility of water aeing testec..

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Corrective Actions

- Using commercial-grac.e ruler.

(:.2/0L/96)

- Evaluating new method of measurement / frequency of surveillance.(03/31/97)

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Excessive Silt i Accumulation l ,

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Root Cause l

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i - Misunderstanding that operab'ility .

is not typically affectec. by Non-Tech Spec surveillances.

The practice was to re-distribute the silt and and leave the surveillance within the acceptance criteria.

This practice had not been questioned by management from the initial surveillance execution. (The surveillance was originally written in 1990 in response to GL 89-13)

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Excessive Silt

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Accumulation - cont.

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Corrective Actions -

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- Siit anc debris removed :from i SXCT. (12/02/96) .

- Inspected and removed silt from l RSH. (12/1:./96)

- Rein:Porce Management l Expectations

! * Clarify management expectations

regarding Non-Tech Spec

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surveillances: (01/14/97)

- scheduling j - tracking l - performing l - reporting failures

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Excessive Silt  !

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Accumulation - cont.

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Reinforce Management l Expectations - cont.

l Department Heads discussed l management expectations regarding l l Non-Tech Spec surveillances at j department tailgates. (01/22/97)

Station Predefine (Surveillance)

Coordinator discussed management l expectations regarding Non-Tech l Spec surveillances with !

departmental Predefine

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(Surveillance) coordinators.

(01/17/97)

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Excessive Silt

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Accumulation - cont.

i - Reinforce Management l Expectations - cont.

Include discussion of management i expectations regarding Non-Tech l.

Spec surveillances in periodic training. (05/30/97)

l Perform a review of executed Non-

Tech Spec surveillances by Site l Quality Verification to ensure that l

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management's expectations are j being met. (05/15/97)

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Excessive Silt

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Accumulation - cont.

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Corrective Actions - cont.

- Correct conflicting arogram l requirements

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Revise Essential Service Water

) Non-Tech Spec surveillances prior l to the next execution to ensure they:

! - Address potential operability impacts i - Address immediate notification of j supervisor and Shift Manager if j surveillance fails to meet any

{ acceptance criteria

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Excessive Silt

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Accumulation - cont.

l - Correct conflicting program j requirements - cont.

l Review ALL Non-Tech Spec j surveillances that perform testing on

safety-related equipment. (07/30/97)

l * Revise various station procedures:

- Conduct of Testing Manual. (03/01/97)

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{ - Predefine (surveillance) program

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procedures. (08/01/97)

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- The procedure writers guide to ensure.

consistent guidance for developing all surveillances. (08/01/97)

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!l Degraded Trash Rack

! Grating

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Root Cause l

- Lack of c esign basis knowle'c.ge .

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Corrective Actions l - Fixec trasa racks (: 1/13/96) '

- Enaance Foreign Materie.

l Exclusion (FME) control:Por degraded trasa racks. (03/31/97)

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Degraded Trash Rack l Grating - cont.

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Corrective Actions - cont. '

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l - Backlog review .

Reviewed ALL open and canceled l work requests for Essential Service l Water and ALL other systems. l

(12/20/96)

Improve formal tracking mechanism !

for system engineers to improve work request backlog review.

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(08/01/97)

Enhanced Action Request (AR)

screening. (9/96)

Revise System Engineer Handbook on guidelines and management expectations on how to address low priority work requests. (03/31/97)

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ll LFSAR Discrepancies on SX Cooling Tower

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! Design Features

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Root Cause

! - Pre-startua cognitive personnel l error.

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Corrective Actions i

l - Update UFSAR anc. plant design

! c.ocuments to reflect correct l design configuration. (04/30/97)

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Inadequate SX Makeup

Calculation

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Root Cause l - Cognitive personnel error (~.992)

! Didn't account for design l configuration of Ultimate Heat Sink j (UHS) regarding volumetric

requirements.

- Didn't consider acceptance criteria for j silt buildup.

l - Didn't take into account the anti-vortex l box geometry.

! - Selfidentified j

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Corrective Actions

- Re-perform UHS calculations (03/:.4/97)

- Incorporate results of the calculations into surveillances and procedures. (03/31/97) 31

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e ADDITIONAL ISSUE

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Design Basis Knowledge

- The design aasis knowlec.ge le.ve.

of selectec. p.. ant personnel was !

compared to management's l expectations curing the level 2 i

! root cause. Several concerns

were ic entifiec :

Design basis responsibility was unclear for certain processes.

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Management expectations regarding design basis knowledge requirements are not clearly and consistently conveyed.

Design basis training needs to be enhanced.

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- Corrective Actions Comed is implementing Division-wide process improvement initiative (NSWP)in 1997 to address UFSAR/ Design Basis Conformance.

It is to include:

- Management Expectations

- Define explicit roles and responsibilities for entire organization l - Provide tiered training for nearly all I personnel (in '97)

- Defines standard process for self l assessment reviews l

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CORRECTIVE

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ACTIONS - cont.

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In summary our short term .

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corrective actions were focused -

m restoring the SX System, our l long term actions are focused on

! design basis knowledge,

) increased sensitivity and I

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reinforcing management l l expectations and. standards. l

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OPEN ISSUES

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Essential Service Water Strainer

!- - Identifiec holes in 1B/L A

Essentia Service Water Pum15 3ackwash strainer elements.

! - Appears to have 3een caused ay

) flowinducec erosion.

- Corrective Actions Replaced all elements in 1B

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Essential Service Water strainer.

l (01/11/97)

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- Sent elements to SMAD and vendor for l analys~is.

l Inspected and replaced all elements I in 1A Essential Service Water

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strainer. (01/17/97)

Scheduling inspections and possible

element replacement in 2A/2B

Essential Service Water strainers.

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OPEN ISSUES - cont.

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Reactor Containment Fan l Cooler (RCFC) Flow Concern

! - November's monti y surveillance, aerformec.1./22/96, l :Pailec acceatance criteria -for the

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~ D RCFC. (Dec_ared inocerable)

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- Corrective' Actions j Entered LCOAR

Performed forward flushing of the

! system. (11/24/96)

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Performed a flow balance.

(11/26/96)

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l OPEN ISSUES - cont. l

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, - Corrective Actions - cont.  !

Completed a heat capacity verification. (11/27/96) l i

Exited LCOAR Performing the surveillance on an increased frequency - from monthly to weekly.

l Making preparations for opening the j 1D RCFC. (Tentative 02/09/97)

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SAFETY

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SIGNIFICANCE '

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Mitigating conservatism's:

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Conservatism's in the calculation relative to SX M/U Pos

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Conservatism in the time -

response by the operators

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Length o:Ptime to deplete the water in the SXCT is long in light of procecures and guic.ance

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available to operators to ensure adequate water is available.

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CONCLUSIONS l

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In summary, our failure to recognize i t:ae significance of the issues i i associatec. wit:1 t;ae SX system was l c.ue to three root causes associated wit:a work control screenings, arocec.ure inadequacy, anc. lack of c.esign aasis .a10wlec.ge.

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CONCLUSIONS -

Cont.

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Looking at t ae big picture - we dicn't taxe promat action, aut once -

we recognizec. the extent of the issues, our corrective actions were l arompt anc. extensive. Although we be..ieve that actual safety significance was minimal, we do not discount the significance of the issues overall.

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We understand the issues of concern to t:ae NRC anc. I hooe we have demonstratec. to you t:aat we have a thorough understanding ofthe issues, as we have discussed, and are

! taking appropriate corrective actions.

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ENCIDSURE 3

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BYRON NUCLEAR POWER STATION l

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! ESSENTIAL SERVICE WATERISSUES l

l SUMMARY OF PRE-DECISIONAL ENFORCEMENT CONFERENCE PRESENTATION JANUARY 24,1997 l

NRC REGION III LISLE, ILLINOIS i

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AGENDA l

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Opening Remarks Ken Graesser Overview Kurt Kofron Investigation Team Rod Freidel Issues and Corrective Actions Dave Wozniak Conclusions Ken Graesser

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. OPENING REMARKS We will be addressing the issues conceming the Essential Service Water event at Byron.

More importantly, we intend to discuss our specific corrective actions, which are broad based and in-depth. We have developed an action plan with specified completion dates.

After the initial discovery of the sitting problem, the approach we took and are continuing l to take is to make sure we have a conservative safety focus. We need to assure you that l uncompromising nuclear safety is our absolute target.

l We are very disappointed by this event, as our cornerstones are "not to defer '

l

maintenance" and "promptly recognize and resolve issues". We did not do the job in this case.

We are communicating to our organization the need to do what is right regardless of l whether a surveillance is Technical Specification or Non-Technical Specification related.

Surveillances need to be reviewed for operability to assure enhanced safety, reliability, and availability. It is my expectation that all surveillances, Tech Spec or Non-Tech Spec, receive the same level of review, rigor and prompt disposition.

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OVERVIEW  !

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On October 15.1996, a Problem Identification Form (PIF) was generated when the Essential Service Water Cooling Tower (SXCT) silt inspection surveillance did not pass !

i acceptance criteria. An operability assessment was completed. The SXCT basin level

was increased on 10/18/96 as a compensatory action.

.

Management made a conscious decision to continue work on the Unit 2 System Auxiliary l Transformers and their associated ductwork, while continuing to look at the SXCT.

!

.

During initial restoration activities, other issues were identified:

,

e Fallen trash racks.

. Trash rack bolting and level switch mounting corrosion. l

. Error in Ultimate Heat Sink (UHS) calculation.

. Foreign material exclusion (FME) concerns in and around the SXCT basin.

i Based on the growing number ofissues identified between 10/18/96 and 11/04/96, I escalated the issue and chartered a Level 2 investigation on 11/04/96. Two teams were formed: a working group to restore the design configuration of the UHS, and a group to determine the root cause and identify appropriate corrective actions.

The UHS restoration was accelerated, and the silt and debris was removed from SXCT basins. The trash racks and trash rack bolting was fixed; the River Screen House (RSH)

was inspected and the silt was removed. Heat exchanger inspections were performed.

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ISSUES and CORRECTIVE ACTIONS

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+ Inadequate Acceptance Criteria

+ Inadequate Test Control

'

+ Excessive Silt Accumulation

+ Degraded Trash Rack Grating .

.

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+ UFSAR Discrepancies on SX Cooling Tower Design Features -

+ Inadequate SX Makeup Calculation

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Inadequate Acceptance Criteria

,

' * Root Cause

* Poor engineering review.

i * Lack of a questioning attitude.

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The original acceptance criteria were generated by an Architect Engineer letter, dated May 17,1990. There was no clear basis for the acceptance criteria and the product review was poor.

.

• Corrective Actions

• The Service Water Cooling Tower (SXCT) silt was removed.

• An elevated SXCT basin level is being maintained (97%).

• All Non-Tech Spec surveillances that perform testing on safety-related equipment are being reviewed to ensure they:

. Provide clear, valid, and consistent acceptance criteria.

. Acceptance cri teria refers to design basis where applicable.

• Engineering is relying less on outside engineering.

. 70 - 80% of the engineering activities are being performed in house.

f

!

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Inadequate Test Control

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.

e Root Cause

• An established practice of using non-M&TE methods existed due to extremely low visibility of water being tested.

. Corrective Actions

• The use of a commercial-grade ruler has been implemented.

• New measurement methods and surveillance frequency is being evaluated.

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. Excessive Silt Accumulation i

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• Root Cause I

• A misunderstanding existed that operability is not typically affected by Non-Tech Spec surveillances.

. The practice was to re-distribute the silt and leave the surveillance within the acceptance criteria.

. This practice had not been questioned by management from the initial surveillance execution.

. The surveillance was initiated in response to Generic Letter 89-13.

• Corrective Actions

• Silt and debris was removed from SXCT.

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• RSH was inspected and the silt was removed.

• Management expectations regarding scheduling, tracking, performing and I reporting surveillance failures were clarified for Non-Tech Spec surveillances.

• Department heads discussed management expectations regarding Non-Tech Spec surveillances at department tailgates.

• Station Predefine (Surveillance) Coordinator discussed management expectations regarding Non-Tech Spec surveillances with departmental Predefine (Surveillance) Coordinators.

• Management expectations regarding Non-Tech Spec surveillances will be included in periodic training, i'

• To ensure that management's expectations are properly communicated, understood and implemented, Site Quality Verification will perform an assessment of executed Non-Tech Spec surveillances for compliance.

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* In addressing conflicting program requirements each Essential Service Water

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Non-Tech Spec surveillance will be revised prior to it's next execution. !

All Non-Tech Spec surveillances that perform testing on safety-related I

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equipment will be reviewed.

• Various station procedures will be revised:

! . Conduct of Testing Manual.

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Predefine (surveillance) program procedures.  ;

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. The procedure writers guide to ensure consistent guidance for developing all surveillances.

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. Degraded Trash Rack Grating

• Root Cause

. Lack of Design Basis Knowledge

. The impact on system operability was not recognized.

. - Corrective Actions .

• The trash racks were repaired

Enhanced Foreign Materiel Exclusion (FME) control for degraded trash racks ,

was implemented.

• Backlog review enhancement

. Action Request (AR) screening was enhanced.

. All open and crcuceled work requests for all systems were reviewed

. The recognition of significant issues is being improved by providing engineering review of new work requests.

. The System Engineer Handbook is being revised to address management expectations and guidelines on low priority work requests.

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- - UFSAR Discrepancies on SX Cooling Tower Design Features

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. Root Cause The cooling tower design was changed prior to initial licensing. While the new i

design change was reflected in the FSAR, one design detail was not deleted from one

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drawing.

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. Corrective Actions

In 1996, UFSAR reviews were performed on the Containment Spray, Radwaste and Spent Fuel Pool. Currently, a SSFI-type review is being conducted on the Residual '

Heat Removal System. To date, all discrepancies found during these reviews have ,

been dispositioned via the 50.59 process and no unreviewed safety questions exist.

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Inadequate SX Makeup Calculation

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• Root Cause The investigations identified that personnel doing the calculation in 1992 did not account for the silt in the basin or take into consideration the anti-vortex box geometry.

• Corrective Actions As a compensatory measure an elevated SXCT basin level of 97% is being maintained until the calculations are re-performed. When the calculations are ,

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completed, the proper acceptance criteria will be incorporated into the surveillance -

procedures. A Tech Spec change will be submitted ifit is required.

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~] SAFETY SIGNIFICANCE

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The safety significance is minimal because the SX makeup calculation utilized a conservative basin volume that does not include the additional water volume in the air intake areas at higher basin levels. This additional water volume is approximately 27,000 gallons which is -6.5 inches of water in the bottom of the SX basin.

, The SX makeup calculation assumes a two hour delay after the start of the accident to

' start the deep well pump. Based on simulated events the deep well pump would most likely be started 75 minutes into the event. Earlier initiation of makeup results in an additional 24,750 gallons of water which is -6 inches of water in the bottom of the SX basin.

The SX makeup calculation assumes no operator action to balance the SX supply and return flows from the tower basins. This results in one basin emptying and the other basin remaining full to the overflow between the basins. Operator action would most likely be taken to redistribute SX flow and utilize the water in both basins. The SX basin low level alarm would provide indication of the low level problem in one basin and ~14 hours would be available for recovery actions after the alarm occurs before the basin low

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level is reached.

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, CONCLUSIONS

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a in summary, our failure to recognize the significance of the issues associated with the SX system was due to three root causes associated with work control screenings, procedure inadequacy, and lack of design basis knowledge. This lack of recognition led to untimely i corrective action for conditions identified in 1993 with repect to the degraded conditions within the SX system. To correct these problems, we intend to improve our ability to recognize issues. These actions include:

• improving our recognition of significant issues by providing engineering review l of new work requests, l

• performing periodic reviews of the backlog of open work requests to recognize _i high priority issues, j

• clearly communicating management expectations for all personnel with respect !

to surveillance perfonnance,

• increasing the design basis knowledge throughout our organization.

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