Information Notice 1999-30, 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.
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
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
Technical Contact:
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
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
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
Technical Contact:
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
1 i
i
i
r'
Elizabeth Q. Ten ~ ~ ~ k , Director
Division of Fuel Cyqle Safety
and Safeguards /
Office of Nuclear ,Material Safety
and safeguards
i
Technical Contact:
Dennis C. Morey, NMSS
301-475-6107 it
i
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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