05000301/LER-1997-001-01, :on 970107,containment Liner Clearance Was Not IAW Plant Design Basis.Caused by Void Between Containment Liner & Concrete Containment Structure.Inspected Containment

:on 970107,containment Liner Clearance Was Not IAW Plant Design Basis.Caused by Void Between Containment Liner & Concrete Containment Structure.Inspected Containment

ML20134H778
Person / Time
Site:	Point Beach
Issue date:	02/06/1997
From:	Weaver D WISCONSIN ELECTRIC POWER CO.
To:
Shared Package
ML20134H776	List: 05000301/LER-1997-001, Forwards LER 97-001-00,re Containment Structure Where Internal Containment Structural Members Could Have Damaged Containment Liner During Safe Shutdown Earthquake 05000301/LER-1997-001-01, :on 970107,containment Liner Clearance Was Not IAW Plant Design Basis.Caused by Void Between Containment Liner & Concrete Containment Structure.Inspected Containment
References
LER-97-001-01, LER-97-1-1, NUDOCS 9702110462
Download: ML20134H778 (4)

LER-1997-001, on 970107,containment Liner Clearance Was Not IAW Plant Design Basis.Caused by Void Between Containment Liner & Concrete Containment Structure.Inspected Containment

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(x) 10 CFR 50.73(a)(2) 10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition
3011997001R01 - NRC Website

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1 NRC FORM 366 U.S. NUCLEAR REGUL ATORY COMMIS&lON APPROVED BY OMB NO. 3160 4104 14-95) '

EXPIRES 04/30/96 ESTIMATED BURDEN PER RESPONSE TO COMPLY WITH THIS INFORMATION COLLECTION REQUEST: 50.0 HRS.

LICENSEE EVENT REPORT (LER)

REPORTED LESSONS LEARNED ARE INCORPORATED INTO THE LICENSING PROCESS AND FED BACK TO INDUSTRY.

FORWARD COMMENTS REGARDING BURDEN ESTIMATE (See reverse for required number of TO THE INFORMATION AND RECORDS MANAGEMENT digits / characters for each block)

BRANCH (T-6 F33),

U.S.

NUCLEAR REGULATORY COMMISSION, WASHINGTON, DC 20555M1. AND TO THF PAPERWORK REDUCTION PROJECT I FACILITY NAME (1)

DOCKET NUMBER (2)

PAGE (3)

Point Be:ch Nuclear Plant, Unit 2 05000301 1 OF 4 I TITLE 14)

Containment Liner Clearance Not In Accordance With Plant Design Basis l

FVENT DATE (5) l LER NUMBER 16)

REPORT DATE (7)

OTHER FACILITIES INVOLVED (8) l MONTH I YEAR I YEAR SEQUENTIAL REVISION F ACILITY NAME DOCKET NUMBER J

DAY NUMBER NUMBER MONTH DAY YEAR 05000 J

l01 07 l 97 l 97 001 --

00 02 06 97 05000 l

FACILITY NAME DOCKET NUMBER I

CPERATING l THis REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR 4: (Check one or more) (11) l j

MODE (9)

N 2o.220m 2o.22o3:aH2Hv) bo.73(aH2Ho 50.73<aH2Hvoo POWE R l

?O.2203(aH1) 20.2203(aH3Hi)

)(

50.73(sH2Hii) 50.73(a)(2)(x)

LEVEL (10) 000 20.2203<aH2Ho 20.2203<aH3Hio 50.73(a>t2Hiin 73.71 20.2203(aH2His) 20.2203(aH4) 50.73(a)(2)(ivl OTHER 20.2203(aH2Hm!

50.36tcH1) 50.73(aH2Hv) speaty m Abstrect below I

20.2203(all2Hivl 50.36tcH2) 50.73(aH2Hvii) or in NRC Form 366 A LICE N CONTACT FOR THIS LER (12) lNAME TELEPHONE NUMBER tinclude Area Code) j David Weaver (414) 221-3418 COMPLETE ONE LINE FOR E ACH COMPONENT F AILURE DESCRIBED IN THt$ REPORT 113)

CAUSE

SYSTE M COMPONENT MANUFACTUREH REPORTABLE

CAUSE

SYSTEM l COMPONENT MANUFACTURER REPORTABLE TO NPROS

[

TO NPRDS SUPPLEMENTAL REPORT EXPECTE D (14) bCTED MONTH DAY YEAR I

YES SUBMISSION (11 yes, complete EXPECTED SUBMIS$10N DATE).

X NO DATE (15)

ABSTRACT (Llrrut to 1400 spaces,4 e., approximately 15 single-spaced typewntten knes) (16)

On January 7, 1997, while Point Beach Nuclear Plant (PBNP) Unit 2 was shut down and defueled during its annual refueling outage, plant personnel identified one location where the clearance between internal Unit 2 containment structures and the containment liner was not in accordance with the plant design basis.

During a containment inspection /walkdown of Unit 2, plant personnel noted that the Unit 2 "A" containment accident fan platform was in contact with the containment liner located opposite to an i

indicated void betwcan the containment liner and concrete containment i

ctructure.

This configuration could have resulted in a containment breach during a safe shutdown earthquake which is contrary to the plant design b sis.

The Unit 2 containment structure was immediately declared inoperable.

Plant engineers walked down the remainder of the Unit 2 containment and documented eight additional locations of concern.

The Unit 1 containment was also inspected, and although several areas of concern were identified, further evaluations determined the Unit 1 containment to be operable.

9702110462 970206 PDR ADOCK 05000301 S

PDR

l lU.S. NUCLEAJ RE AULATOaY COMMis&lON I

(4 95) l LICENSEE EVENT REPORT (LER) l TEXT CONTINUATION FACILITY N AME (1)

DOCKET NUMBER (2)

LER NUMBER (6)

PAGE (3)

I YEAR SEQUENTIAL REVISION l

Point Beach Nuclear Plant, Unit 2 05000301 NUMM R NUMMR 2 OF 4 97 001 00 itxT Uf more space is inuked, use adddoonal copes of NRC form 366A) (17)

Event Description

On January 7, 1997, while Point Beach Nuclear Plant (PBNP) Unit 2 was shut down and defueled during its annual refueling outage, plant personnel identified one location where the clearance between internal Unit 2 containment structures and the containment liner was not in accordance with the plant design basis.

During a containment inspection /walkdown of Unit 2, plant personnel noted that the Unit 2 "A" containment accident fan platform was in contact with the containment liner located opposite to an indicated void between the containment liner and concrete containment structure.

This configuration could result in a breach of containment during a safe shutdown earthquake due to differential movement and subsequent penetration of the structure through the liner.

This is contrary to the plant design basis which states the containment structural members are designed to accept a combination of normal operating loads and safe shutdown earthquake (SSE) loads without exceeding specified stress limits The Unit 2 containment was immediately declared inoperable.

Plant engineers walked down the remainder of Unit 2 containment and documented eight additional locations with smaller than expected ~ clearances.

However, they determined that the associated structures / components would not promote damage to the liner.

The decision was made to assess the operability of the Unit 1 containment structure. Plant engineers entered Unit 1 containment on January 7,

1997, and identified 12 locations of concern.

A prompt operabillty review determined that the Unit 1 containment was operable based upon the structural design and configuration of the associated structures.

Component and System Description:

The reactor containment structure is a right cylinder with a flat base and a shallow domed roof.

A 1/4 inch thick steel liner is attached to the inside face of the concrete shell to ensure a high degree of leak tightness.

The base liner is installed on top of the structural slab and is covered with concrete.

The structure provides biological shielding for both normal and accident conditions.

The reactor containment is designed as a seismic Class 1 structure.

Class 1 structures and components are those whose failure might cause or increase the severity of a loss-of-coolant accident or result in an uncontrolled release of excessive amounts of radioactivity.

Class 1 structures and components also include those which are vital to the safe shutdown and isolation of the reactor.

The containment structural members are designed to accept a combination of normal operating loads and safe shutdown earthquake (SSE) loads without exceeding specified stress limits.

NHC f ORM 366A 14-95)

Mhc FORM 366A U.S. NUCLEAR REEULATORY COMMISSION (4 95)

LICEWSEE EVENT REPORT (LER)

TEXT CONTINUATION FActLITV NAME til DOCKET NUMBER (2)

LER NUMBER to)

PAGE (3)

YEAR SEQUENTIAL REVISION Point Beach Nuclear Plant, Unit 2 05000301 NUMMR NUMER 3OF4 97 001 00 TEKT Ut anere space in requked, use additionalcopies of NRC Form 366M (17)

Corrective Actious 1

The Unit 2 containment was immediately declared inoperable.

A prompt operability review determined the Unit 1 containment to be operable.

All identified Unit 2 containment liner clearance deficiencies will be resolved prior to Unit 2 core load, currently scheduled to commence on February 13, 1997.

]

The Unit 1 containment liner clearance deficiencies will be corrected during the next Unit i refueling outage, which is currently scheduled to commence on May 9, 1997.

I

Cause

Further review of this plant configuration identified that all containment liner clearance deficiencies have existed since original plant construction.

Reportability

This Licensee Event Report is being submitted in accordance with the

)

requirements of 10 CFR 50.73 (a) (2) (ii) (B), "Any event or condition that resulted in the nuclear power plant being in a condition that was outside the design basis of the plant."

A 4-hour report to the NRC was made for Unit 2 under 10 CFR 50.72 (b) (2) (i).

The NRC resident inspectors were also notified.

Safety Assessment

This event involved the potential breach of the containment liner due to contact from structural members during a seismic event.

Of the nine areas of concern for Unit 2, eight were determined to not be safety significant due to the design of the involved structural members.

Based on engineering judgment, if these members would have contacted the containment liner during a seismic evsnt, the members would have buckled prior to damaging the containment liner.

.c

{orm for the containment However, it was determined that the suppcy+

accident recirculation fan (2-W1A1) and tL_ containment cooling fan (2-W1A2) could have punctured the containment liner during a safe shutdown earthquake.

Connecting bolts on the structure are located opposite to an indicated void between the containment liner and the concrete containment structure.

Had this caused a breach in containment during a seismic event coincident with a loss-of-coolant accident (LOCA), a radiological release could have resulted.

However, the probability of a safe shutdown earthquake occurring at PBNP within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> following a LOCA is 1.3E-9 per year, or once every 769,230,769 years.

Therefore, this plant condition created essentially no additional risk to plant personnel and the general public.-

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NRC FORM 306A U.S. NUCLEAM f.EOJ.ATORY COMM4SION e

(4 95) i LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION r

FActLfTV NAME til DOCKET NUMBER (2)

LER NUM8ER (S i

PAGE 13)

YEAR SEQUENTIAL REVISION Point Beach Nuclear Plant, Unit 2 05000301 NUusEn NousER 4OF4 l

97 001 00 1

TEXT (11anore space os required, use additenalcopes of NRC form 366A) (17)

Similar occurrences:

No previous events have been identified involving the containment ctructure being outside of its design basis.

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