Information Notice 1999-30, Failure of Double Contingency Based on Administrative Controls Involving Laboratory Sampling and Spectroscopic Analysis of Wet Uranium Waste

Failure of Double Contingency Based on Administrative Controls Involving Laboratory Sampling and Spectroscopic Analysis of Wet Uranium Waste

ML993060157
Person / Time
Issue date:	11/08/1999
From:	Teneyck E NRC/NMSS/FCSS
To:
Ten-Eyck E
References
IN-99-030
Download: ML993060157 (7)

UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF NUCLEAR MATERIAL SAFETY AND SAFEGUARDS

WASHINGTON, D.C. 20555 November 8, 1999 NRC INFORMATION NOTICE NO. 99-30: FAILURE O f DOUBLE CONTINGENCY BASED

ON ADMlNlSTRATlVE CONTROLS INVOLVING

LABORATORY SAMPLING AND

SPECTROSCOPIC ANALYSIS OF WET URANIUM

WASTE

Addressees

All fuel cycle licensees and certificants performing laboratory analysis to determine uranium

content, in support of administrative criticality safety controls.

Purpose

The U.S. Nuclear Regulatory Commission (NRC) is issuing this information notice to alert

addressees to problems recently noted with the laboratory and spectroscopic analysis of

uranium contaminated material. Under certain conditions, incomplete dissolution of samples

may produce a nonconsewative laboratory result and lead to violation of criticality safety limits.

When the laboratory sampling is backed up by spectroscopic analysis, care must be taken to

ensure a sufficiently precise result through proper qualification of the spectroscopic method.

Recipients are expected to review this information for applicability to their facilities and consider

actions, as appropriate, to avoid similar problems. Suggestions contained in this information

notice are not NRC requirements. Therefore, no specific action nor written response is required.

Descri~tionof Circumstances:

On August 12, 1999, a fuel cycle licensee determined that a laboratory dissolution process was

not completely dissolving the uranium in certain samples, which resulted in underestimating the

amount of uranium in wet process waste. Subsequent licensee gamma spectroscopic analysis

of the wet waste also failed to detect the problem, because of inadequate spectroscopic analysis

conditions. Because of these simultaneous failures, excessive uranium was transferred into the

wet process waste storage arrays. These deficiencies in sampling and spectroscopic analysis

of process waste degraded the margin of safety to the extent that a criticality safety limit was

violated.

IN 99-30

November 8, 1999 Discussion:

On July 30, 1999, a fuel cycle licensee discovered that a combustible waste bag containing

laboratory filter paper had higher than expected radiation readings. A subsequent licensee

investigation revealed that the acid leach dissolution process used to prepare samples for

analysis of uranium content had not completely dissolved the uranium. When the samples were

later filtered during the sample preparation process, some uranium was deposited on the filter

paper with other solids.

The samples in question came from a uranium recovery process that produced wet solid waste

that was collected into 5-gallon buckets and stored in a safe, single-layer array. The samples

were used to determine uranium content before the material was further collected into

55-galon drums. Once the waste was collected into the 55-gallon drums, the drums were

examined by spectroscopic analysis before being stored in a safe, triple-layer array.

The licensee investigation revealed that the 55-gallon drum spectroscopic analysis was also

assigning a low value to the uranium content of the drums. This was because the drum

catibration standard did not adequately resemble the material being counted and the

spectroscopic analysis did not account for self-shielding in the drum material.

The licensee had completed a criticality safety anatysis (CSA) of the tripte-layer drum storage

array to establish safety parameters. The analysis made use of the surface density method to

establish the maximum uranium content limit for individual drums. Double contingency for the

storage array was maintained through sampling of the 5-gallon buckets and spectroscopic

analysis of the 55-gallon drums. As a result of these independent and simultaneous failures, drums stored in the array exceeded the maximum allowed uranium content for single drums by

up to 32%, thereby causing the failure of the double-contingency arrangement. This situation

was safety significant in that no controls remained to limit the mass in the array, although the

total mass involved was far less than what would be required for a criticality.

An important contributing factor in this event was the limited scope of the wet waste material

process CSA, which stopped with the material being placed into 5-gallon buckets and did not

overlap the CSA covering the 55-gallon drum storage. Including the transfer from 5-gallon

buckets to 55-gallon drums in the wet waste material CSA should have resulted in more robust

controls such as a requirement for dual sampling before permitting the transfer.

An additional important contributing factor in this event was that the sample processing

procedures allowed a choice of dissolution methods under the assumption that either dissolution

method would produce a substantially similar result. The procedure writers mistakenly

assumed that the acid leach dissoiution method of sample preparation would put all uranium into

solution even if the entire sample was not dissolved.

Finally, the spectroscopic analysis procedures did not qualify waste streams for spectroscopic

analysis, ensure optimal packaging for spectroscopic analysis, or require corrective action, when spectroscopic analysis results did not support laboratory analysis. Spectroscopic analysis

IN 99-30

November 8, 1999 of the 55-gallon drums failed to detect the drums containing excess uranium due to these

failures. ANSI N15.20-1975 "Guide to Calibrating NondestructiveAssay Systems" provides a

more complete discussion of spectroscopic analysis sensitivities.

This event highlights the necessity for careful review of administrative controls, to ensure that

the failure of such controls is actualty unlikely. tn addition, CSAs need to be broad enough that

the analyst will clearly understand the safety significance of proposed controls. All procedures

having an impact on the control need to be reviewed carefully to ensure that the control is

actually implemented.

It is expected that addressees will evaluate the above information for applicability to licensed

activities. This information notice requires no specific actions nor written response. If you have

any questions about the information in this notice, please contact the technical contact listed

below or the appropriate regionai office.

Ap

ck, Dire

~ i v i $ o nof ~ u eCycle

l Safety

and Safeguards

Office of Nuclear Material Safety

and Safeguards

Dennis C. Morey, NMSS

301-415-6107 E-mail: dcm~nrc.gov

Attachments:

1. List of Recently Issued MMSS Information Notices

2. List of Recently issued NRG Information Notices

Attachment I

IN 99-30

November 11, 1999 LIST OF RECENTLY ISSUED

NMSS INFORMATION NOTICES

Information Date of

Notice No. Subject Issuance Issued to

99-29 Authorized Contents of Spent 10128199 All power reactor licensees and

Fuel Casks spent fuel storage licensees and

applicants

99-28 Recall of Star Brand Fire 913Oig9 Alt holders of licenses for nuclear

Protection Sprinkler Heads power, research and test reactors, and fuel cycle facilities

99-27 Malfunction of Source Retraction 9/2/99 All medical licensees authorized

Mechanism in Cobalt-60 Teletherapy to conduct teletherapy treatments

Treatment Units

99-26 Safety and Economic 8/24/99 All Distributors andlor

Consequences of Misleading Manufacturers of Generally

Marketing Information Licensed Products

99-24 Broad-Scope Licensees' 7112/99 All medical licensees' of broad- Responsibilities for Reviewing and scope and master materials

Approving Unregistered Sealed ticensees

Sources and Devices

Safety Concerns Related To All U.S. NRC medical licensees

Repeated Control Unit Failures authorized to use brackytherapy

of the Nucletron Ciassic Model sources in Nucletron Classic

High-Dose-Rate Remote Model high-dose-rate ((HDR)

Afterloading Brachytherapy remote afterloaders

Devices

?O CFR 34.43(a)(I): Effective 6/25/99 Industrial Radiography Licensees

Date for Radiographer Certification

and Plans for Enforcement Discretion

Contingency Planning for the 6125199 All material and fuel cycle

Year 2000 Computer Problem licensees and certificate holders

Update on NRC's Year 2000 6114199 All material and fuel cycle

Activities for Materials Licensees licensees and certificate

and Fuel Cycle Licensees and holders

Certificate Holders

Federal Bureau of Investigation's 5/28/99 A11 US. Nuclear Regulatory

Nuclear Site Security Program Commission fuel cycle, power

reactor, and non-power reactor

licensees

Attachment 2 IN 99-30

November 2 I , 1999 Page 1 of l

LIST OF RECENTLY ISSUED

NRC INFORMATION NOTICES

Information Date of

Notice No. Subject Issuance Issued to

99-29 Authorized Contents of Spent 10/28/99 All power reactor licensees and

Fuel Casks spent fuel storage licensees and

applicants

Recall of Star Brand Fire All holders of licenses for nuclear

Protection Sprinkler Heads power, research, and test

reactors, and fuel cyde facilities

Malfunction of Source Retraction 9/2/99 All medical licensees authorized

Mechanism in Cobalt-60 Teletherapy to conduct teletherapy treatments

Treatment Units

Safety and Economic 8/24/99 All Distributors and/or

Consequences of Misleading Manufacturers of Generally

Marketing Information Licensed Products

Year 2000 Contingency Planning 8/10/99 All holders of operating licenses

Activities for nuclear power plants and fuel

cycle facilities

Broad-Scope Licensees' 7/2 2/99 All medical licensees of broad- Responsibilities for Reviewing scope and master materials

and Approving Unregistered licensees

Sealed Sources and Devices

Safety Concerns Related To 7/6/99 All U.S. NRC medical licensees

Repeated Control Unit Failures authorized to use brachytherapy

of the Nucletron Classic Model sources in Nudetron Classic

High-Dose-Rate Remote Model high-dose-rate (HDR)

Aferloading Brachytherapy remote afterloaders

Devices

10 CFR 34.43{a)(l); Effective 7/6/99 Industrial Radiography Licensees

Date for Radiographer Certification

and Plans for Enforcement Discretion

OL = Operating License

CP = Construction Permit

IN 99-30

November 8, 1999 of the 55-gallon drums failed to detect the drums containing excess uranium due to these

failures. ANSI N15.20-1975 "Guide to Calibrating Nondestructive Assay Systems" provides a

more complete discussion of spectroscopic analysis sensitivities.

This event highlights the necessity for careful review of administrative controls, to ensure that

the failure of such controls is actually unlikely. In addition, CSAs need to be broad enough that

the analyst will clearly understand the safety significance of proposed controls. All procedures

having an impact on the control need to be reviewed carefully to ensure that the control is

actually implemented.

It is expected that addressees will evaluate the above information for applicability to licensed

activities. This information notice requires no specific actions nor written response. If you have

any questions about the information in this notice, please contact the technical contact listed

below or the appropriate regional office.

Elizabeth Q. Ten Eyck, Director

Division of Fuel Cycle Safety

and Safeguards

Office of Nuclear Material Safety

and Safeguards

Dennis C. Morey, NMSS

301-415-6107 E-mail: dcm@nrc.gov

Attachments:

1. List of Recently Issued NMSS Information Notices

2. List of Recently Issued NRC lnformation Notices

FtLE NAME: a:\99-30.in *See ~reviousconcurrences

C = COVER E = COVER & ENCLOSURE N = NO COPY

OFFICIAL RECORD COPY

.: Ps IN 99-xxx

, 1999 It is expected that addressees will evaluate the above information for applicability to licensed

activities. This information notice requires no specific actions nor written response. If you have

any questions about the information in this notice, please contact the tdchnical contact listed

below or the appropriate regional office.

i

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Elizabeth Q. Ten ~ ~ ~ k , Director

Division of Fuel Cyqle Safety

and Safeguards /

Office of Nuclear ,Material Safety

and safeguards

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Dennis C. Morey, NMSS

301-475-6107 it

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E-mail: dcm@nrc.gov i'

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Attachments: i

1. List of Recently Issued NMSS lnformation ~ o t i c e d

2. List of Recently lssued NRC information Notice,$

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