Information Notice 1993-19, Slab Hopper Bulging

Slab Hopper Bulging

ML031080075
Person / Time
Site:	Beaver Valley, Millstone, Hatch, Monticello, Calvert Cliffs, Dresden, Davis Besse, Peach Bottom, Browns Ferry, Salem, Oconee, Mcguire, Nine Mile Point, Palisades, Palo Verde, Perry, Indian Point, Fermi, Kewaunee, Catawba, Harris, Wolf Creek, Saint Lucie, Point Beach, Oyster Creek, Watts Bar, Hope Creek, Grand Gulf, Cooper, Sequoyah, Byron, Pilgrim, Arkansas Nuclear, Braidwood, Susquehanna, Summer, Prairie Island, Columbia, Seabrook, Brunswick, Surry, Limerick, North Anna, Turkey Point, River Bend, Vermont Yankee, Crystal River, Haddam Neck, Ginna, Diablo Canyon, Callaway, Vogtle, Waterford, Duane Arnold, Farley, Robinson, Clinton, South Texas, San Onofre, Cook, Comanche Peak, Yankee Rowe, Maine Yankee, Quad Cities, Humboldt Bay, La Crosse, Big Rock Point, Rancho Seco, Zion, Midland, Bellefonte, Fort Calhoun, FitzPatrick, McGuire, LaSalle, Fort Saint Vrain, Shoreham, Satsop, Trojan, Atlantic Nuclear Power Plant, Crane
Issue date:	03/17/1993
From:	Burnett R NRC/NMSS/FCSS
To:
References
BL-91-001 IN-93-019, NUDOCS 9303110101
Download: ML031080075 (8)

UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF NUCLEAR MATERIAL SAFETY AND SAFEGUARDS

WASHINGTON, D.C. 20555

March 17, 1993 NRC INFORMATION NOTICE 93-19:

Purpose

This information notice is provided to alert addressees to possible bulging

that may occur in slab hoppers. It is expected that licensees will review the

information for applicability to their facilities and consider actions, as

appropriate, to avoid similar problems. However, suggestions contained in

this information notice do not constitute new Nuclear Regulatory Commission

requirements; therefore, no specific action or written response is required.

Description of Circumstances

In October 1992, a licensee notified an NRC Regional Office that a visual

inspection had identified the bulging of an empty slab hopper used to store

calcined U02 powder. This bulging caused the slab thickness of the hopper to

exceed the safe value specified in the nuclear criticality safety analysis.

As such, this event constituted a nuclear criticality hazard.

At that time, the acting shift supervisor, in conjunction with the safety supervisor, tagged

the slab hopper *out of service," pending further investigation. The bulging

occurred about one-half of an itch from the lower end of the hopper and

comprised an area of about 1 ft .

Subsequently, the event was reported to the

NRC Operations Officer, in accordance with NRC Bulletin 91-01..

The licensee convened an investigation to determine the cause(s) of the slab

hopper bulging and to identify needed corrective actions, to preclude

recurrence. This investigation revealed that, in addition to the originally

cited slab hopper, all other slab hoppers had bulged and exceeded their design

thicknesses, in the same general area as the initial slab hopper.

Accordingly, all were removed from service. Additional analyses of the

initially bulged slab hopper, performed using an ultrasonic examination, revealed that the specified wall thickness was actually thinner than that

specified in the drawings of the slab hopper. At this point, the licensee is

unclear as to whether the hopper was fabricated with thinner material or

material thinning had taken place bechise of extended use.

As a result of

these findings, it was decided that all slab hoppers will remain 'locked out'

until corrective actions identified by the investigation have been

implemented.

Although the licensee has not completed its investigation, the preliminary

conclusion is that bulging occurred because of metal fatigue, caused by

9303110101 x

33-OI~

300040

'-' IN 93-19

March 17, 1993

PRage 2 of 3 extended service, and heat and powder expansion that occurs when UO powder

oxidizes while in the slab hoppers.

The licensee's final investigation will

be reviewed in a subsequent NRC inspection and is considered as an inspector

followup item.

Discussion

The bulging of the slab hoppers used to store UO constitutes a nuclear

criticality threat.

This is so because the inside thickness of the slab

hopper is used as the primary criticality safety control.

Therefore, it is

imperative that all possible events that might perturb the thickness of the

slab hopper be examined. In this instance, however, the licensee did not

examine the possibility of slab bulging as a consequence of the chemical

reaction of U02 with oxygen to form U 08 (which releases energy), or the

hydrostatic forces that result from the associated volume expansion.

In fact, an NRC inspection revealed that the licensee did not have documentation of the

design loading and design criteria for the existing slab hoppers.

Furthermore, no quality assurance program or material specifications for the

slab hoppers existed.

To ensure that adequate safety for the slab hoppers is provided, licensees

with slab hoppers may wish to review their nuclear safety programs and

consider the need to incorporate the following elements:

1. Specifications that identify design loadings, criteria, and methods and

acceptance criteria for the slab hoppers.

2. A QA program for slab hoppers to address all activities, including

design, purchase, fabrication, inspection, operation, and maintenance.

3. A preventive maintenance program that provides for the performance of

routine surveillance and periodic dimensional checks of the slab

hoppers.

In addition, when geometric control is used for nuclear criticality safety, the choice between geometric shapes should be based on the inherent ability of

the equipment to retain its integrity. This is of particular concern for

equipment subject to bending stresses in the side walls during normal and

accident conditions.

The following geometric shapes are listed in descending

order of stability:

spherical, cylindrical, annular, and slab geometry.

It

should be noted that for reasonable sizes and comparable wall thicknesses, each descent of the scale decreases the inherent pressure failure limit of the

vessel by about an order of magnitude.

IN 93-19 March 17, 1993 This information notice requires no specific action or written response. If

you have questions about the information in this notice, please contact the

technical contact listed below or the appropriate regional office.

Robert F. Burnett, Director

Division of Fuel Cycle Safety

and Safeguards

Office of Nuclear Material Safety

and Safeguards

Technical contact:

Marc Klasky, NMSS

twnii cnA-KnA

Attachments: /

/A§ ,J

,

1. List of Recently Issued NMSS Information Notices

2. List of Recently Issued NRC Information Notices

44"Id

EKrause:TE 1/29/93

• See previous concurrence

DOC NAME: 93-19.IN

OFC.

IMUF*

I

IMUF*

I

IMUF*

I

IMSB*

I

IMNS*

I

FCskt A I

NAME

MKlasky:

YTharpe

MTokar

JHickey

FCombs

I

I

DATE

2/03/93

, 2/02/93

2/04/93 I

2/04/93 L2/23/93 I3/1(/93

-

-

-

-

I

D: Fd@S

I

I

I

I

DFC

NAME

Rgdrnett

DATE

3/

Wi/92

.-

OFFICIAL RECORD COPY

, 1993

This information notice requires no specific actioi

you have questions about the information in this n4 technical contact listed below or the appropriate i

Pa

3 of 3 i or writ n response. If

otice, ease contact the

regio

office.

, Director

Cycle Safety

Material Safety

L,

Technical contact:

Attachments:

1. List of Recentl)

2. List of Recentl)

Marc Klasky, NMSS

(301) 504-2504

/

Issued NMSS Information Notices

Issued NRC Information Notices

EKrause:TE 1/29/93

• See previous concurence

1, OC

IU*llIMUF* llIMUF*

lF l MBN

FCSS

NAME

MKlasky:

VTharpe

MTokar

JHickey

1 IJGreeves

DATE

2/03/93 j_2/02/93 l 2/04/93

2/04/93 T

___3 _

2/ /93

=_

OFC

D:FCSS

I

I

I

I

NAMEl

RBurnett

DATE l

2/

/92

.1

-

_

_

_

_

LUCuri

t= 6UVLtK & LtRLU4UKt

N a NU UlOW

OFFICIAL RECORD COPY

G:\\SLAB

IN 93-XX

February

, 1993 This information notice requires no specific act n or written response.

If

you have questions about the information in thi notice, please contact the

technical contact listed below or the appropri te regional office.

Richar E. Cunningham, Director

Divison of Industrial and

Me ical Nuclear Safety

Off ce of Nuclear Material Safety

nd Safeguards

Technical contact:

Marc Klasky, SS

(301)

504-25i4 Attachments:

1. List of Recently Issued N S Information Notices

2. List of Recently Issued

C Information Notices

EKrause:TE ~/29/93 OF

IMUF

I /

IMUFr>

IMUF

7- IMM

I

IMNS

I

IMNS

NAME

MKlaskyffj

Y

MTok

AlkeyGreeves

RCunningham

2/ATE

J._215 /93

_

_

2/__

/93

_

_2/ I93

_2/

4/93

__2/

/93 1

2/ /93 C=COPY

E - COVER & ENCLOSURE

N = NO COPY

OFFICIAL RECORD COPY

G:\\SLAB

IN 93-19 March 17, 1993 This information notice requires no specific action or written response. If

you have questions about the information in this notice, please contact the

technical contact listed below or the appropriate regional office.

Robert F. Burnett, Director

Division of Fuel Cycle Safety

and Safeguards

Office of Nuclear Material Safety

and Safeguards

Technical contact: Marc Klasky, NMSS

(301) 504-2504 Attachments:

1. List of Recently Issued NMSS Information Notices

2. List of Recently Issued NRC Information Notices

Att'achment I

IN 93-19

March 17, 1993 LIST OF RECENTLY ISSUED

NMSS INFORMATION NOTICES

Information

Date of

Notice No.

Subject

Issuance

Issued to

93-18 Portable Moisture-Density

Gauge User Responsibilities

during Field Operations

03/10/93

All U.S. Nuclear Regulatory

Commission licensees that

possess moisture-density

gauges.

93-14

Clarification

10 CFR 40.22,

Quantities of

Material

of

Small

Source

02/18/93

All Licensees who possess

source material.

93-10

93-07

93-05

Dose Calibrator Quality

Control

Classification of Trans- portation Emergencies

Locking of Radiography

Exposure Devices

Investigation and Re- porting of Misadministra- tions by the Radiation

Safety Officer

Recent Revision to

10 CFR Part 20 and

Change of Implementa- tion Date to

January 1, 1994

93-04

02/02/93

02/01/93

01/14/93

01/07/93

01/05/93

12/17/92

10/18/92

All Nuclear Regulatory

Commission medical

licensees.

All Licensees required to

have an emergency plan.

All Nuclear Regulatory

Commission industrial

radiography licensees.

All U.S. Nuclear Regulatory

Commission medical

licensees.

All byproduct, source, and

special nuclear material

licensees.

All Nuclear Regulatory Com- mission Medical Licensees.

All U.S. Nuclear Regulatory

Commission Licensees.

93-03

92-84

Release of Patients

Treated with Temporary

Implants

92-72

Employee Training

and Shipper Registra- tion Requirements for

Transporting Radioactive

Materials

Attachment 2

IN 93-19

March 17, 1993

Page 1 of I

LIST OF RECENTLY ISSUED

NRC INFORMATION NOTICES

1nfnrmatinn

-z

-.

-

Noti c. No.-

Subject

Date of

Issuance

Issued to

Issuance

Issued to

93-18

93-17

93-16

93-15

93-14 Portable Moisture-Density

Gauge User Responsibilities

during Field Operations

Safety Systems Response

to Loss of Coolant and

Loss of Offsite Power

Failures of Nut-Locking

Devices in Check Valves

Failure to Verify the

Continuity of Shunt Trip

Attachment Contacts in

Manual Safety Injection

and Reactor Trip Switches

Clarification of

10 CFR 40.22, Small

Quantities of Source

Material

Undetected Modification

of Flow Characteristics

in the High Pressure

Safety Injection System

Off-Gassing in Auxiliary

Feedwater System Raw

Water Sources

Single Failure Vulner- ability of Engineered

Safety Features

Actuation Systems

Dose Calibrator Quality

Control

03/10/93

03/08/93

02/19/93

02/18/93

02/18/93

02/16/93

02/11/93

02/04/93

02/02/93

All U.S. Nuclear Regulatory

Commission licensees that

possess moisture-density

gauges.

All holders of OLs or CPs

for nuclear power reactors.

All holders of OLs or CPs

for nuclear power reactors.

All holders of OLs or CPs

for nuclear power reactors.

All licensees who possess

source material.

All holders of OLs or CPs

for nuclear power reactors.

All holders of OLs or CPs

for nuclear power reactors.

All holders of OLs or CPs

for nuclear power reactors.

All Nuclear Regulatory Com- mission medical licensees.

93-13

93-12

93-11

93-10

OL = Operating License

CP = Construction Permit