Reporting Mishaps Involving LLW Forms Prepared For Disposal (Generic Letter 91-02)
TO: ALL OPERATORS OF LOW-LEVEL RADIOACTIVE WASTE (LLW) DISPOSAL SITES,
WASTE PROCESSORS, AND ALL HOLDERS OF LICENSES FOR
NUCLEAR FUELS, NUCLEAR MATERIALS AND NUCLEAR POWER REACTORS
SUBJECT: REPORTING MISHAPS INVOLVING LLW FORMS PREPARED FOR DISPOSAL
(GENERIC LETTER 91-02)
For the reasons presented below, the Nuclear Regulatory Commission (NRC) has
decided to rely on voluntary submittal of informational reports by both
waste form generators and processors regarding mishaps to LLW forms prepared
for disposal. This Generic Letter is intended to encourage this action on
such mishaps. Licensees are also reminded of their obligation to report
defects and deviations in accordance with NRC requirements in 10 CFR
NRC has incomplete information on mishaps to LLW forms prepared for
disposal. Four incidents have been reported in which pressurization
resulted from chemical reactions in LLW shipping containers storing
dewatered synthetic organic materials, such as resins (NRC Information
Notices 83-14, "Dewatered Spent Ion Exchange Resin Susceptibility to
Exothermic Chemical Reaction," March 21, 1983; 84-72, "Clarification of
Conditions for Waste Shipments Subject to Hydrogen Gas Generation,"
September 10, 1984; 90-50, "Minimization of Methane Gas in Plant Systems and
Radwaste Shipping Containers," August 8, 1990). Another incident was
reported in which, during solidification of the waste, a violent reaction
occurred between a chemical detergent and a vendor's waste solidification
agent (NRC Information Notice 88-08, "Chemical Reactions with Radioactive
Waste Solidification Agents," March 14, 1988). This reaction resulted in
boiling of the mixture so that it overflowed the liner, then hardened, and
had to be chipped away. Other problems have been encountered in the use of
cement to solidify and stabilize bead resin wastes. Thus, there have been
multiple incidents in which cement-solidified bead resin wastes have either
not solidified properly or have disintegrated over a period of time after
solidification. Although mishaps such as these generally have been made
known to regulatory authorities, mainly through indirect and informal means,
there is presently no established method to encourage the reporting of such
events and the providing of adequate information on them.
Current Practice -
All three currently-sited Agreement States (Nevada, South Carolina, and
Washington) have established requirements in the State licenses for the
reporting of waste form and container deficiencies identified by the site
operators in wastes shipped to the sites for disposal. In addition, all
three facilities have on-site State inspectors who inspect the condition of
shipments received by the disposal-facility operators. This information is
provided to NRC as part of the NRC/Agreement State exchange of information
program. The staff further notes, however, that neither the Agreement
States nor NRC have specific regulatory requirements that apply to all
licensees for reporting of waste form or container deficiencies. Therefore,
the States do report what they find, but they may not find some of these
problems, because they have no requirement to look for all such events at
their disposal facilities, and they do not presently have the means to be
informed routinely of mishaps that occur at NRC-licensed facilities.
Existing reporting requirements contained in 10 CFR 20.403, 50.72, 50.73 and
61.80 do not require reporting of waste form mishap information. The
reporting requirement in 10 CFR Part 21 is associated with
safety-significant defects or noncompliances, and may not be interpreted by
some to cover mishap information.
Classes of Needed Information -
The staff has identified three classes of useful information that interest
NRC and could be reported. These three include:
1. The failure of high-integrity containers used to ensure a stable waste
form. Container failure can be evidenced by changed container
dimensions, cracking, or damage resulting from mishandling (e.g.,
dropping or impacting against another object).
2. The misuse of high-integrity containers, evidenced by a quantity of
free liquid greater than 1 percent of container volume, or by an
excessive void space within the container. Such misuse is prohibited
by 10 CFR 61.56.
3. The production of a solidified Class B or C waste form that has any of
the following characteristics:
- Contains free liquid in quantities exceeding 0.5 percent of the
volume of the waste.
- Contains waste with radionuclides in concentrations exceeding
those considered during waste form qualification testing accepted
by the regulatory agency, which could lead to errors in assessment
of waste class.
- Contains a significantly different waste loading than that used in
qualification testing accepted by the regulatory agency.
- Contains chemical ingredients not present in qualification testing
accepted by the regulatory agency, and those quantities are
sufficient to unacceptably degrade the waste product.
- Shows instability evidenced by crumbling, cracking, spalling,
voids, softening, disintegration, nonhomogeneity, or dimensional
- Evidence of processing phenomena that exceed the limiting
processing conditions identified in applicable topical reports on
process control plans, e.g., foaming, temperature extremes,
premature or slow hardening, and production of volatile material.
Bases for Needed Information -
The voluntary reporting of the three classes of information outlined above
would allow the staff access to information on field experiences with LLW
forms and to determine when modifications to test criteria are necessary.
10 CFR Part 61 establishes certain "minimum"(61.56(a)) and "stability"
(61.56(b)) requirements for LLW, whereas Part 20 (Section 20.311) requires
waste generators and processors to certify that the waste satisfied the
requirements of Part 61. The Nuclear Material Safety and Safeguards (NMSS)
staff reviews topical reports and other documents provided by vendors and
licensees to ensure that the waste-form requirements of Part 61 will be met
and to provide a vehicle with which the certification requirements of Part
20 can be satisfied (by reference). In a parallel effort, the Office of
Nuclear Reactor Regulation (NRR) staff reviews information on
waste-processing equipment and procedures to ensure that 10 CFR Part 50,
App. A, "General Design Criteria for Nuclear Power Plants," is satisfied.
The NRC staff findings of acceptability and adequacy of process-control
provisions affecting the characteristics of the waste-form produced may
require modification, if subsequent experience in the field reveals that the
bases for the approvals are being exceeded or are no longer relevant.
Therefore, to make informed decisions on regulatory action, to inform
licensees of events that may have generic implications, and to make
inspectors aware of the reported information, the staff needs to have
quantitative information on the nature and frequency of occurrence of
mishaps regarding waste form and packaging for disposal.
It is suggested that the voluntary submittal of information regarding
waste-form mishaps be reported within 30 days of the incident to NRC's
Director of the Division of Low-Level Waste Management and Decommissioning
and to the designated State disposal-site regulatory authority.
This request is covered by Office of Management and Budget Clearance Number:
3150-0156, which expires November 30, 1993. The estimated average burden is
approximately 8 person-hours per licensee response, including visual
observation of the waste form mishap, drafting a description of the
observation, and preparing a final mishap report for submittal to NRC.
Comments on the accuracy of this estimate and suggestions to reduce the
burden may be directed to the Office of the Management and Budget, Room
3208, New Executive Office Building, Washington, D.C. 20503, and the U.S.
Nuclear Regulatory Commission, Information and Records Management Branch,
Office of Information Resources Management, Washington, D.C. 20555.
If you have any questions about this letter, please direct them to the
technical contact listed below or to the appropriate regional office.
Richard L. Bangart, Director
Division of Low-Level Waste
Management and Decommissioning,
Technical Contact: Michael Tokar, NMSS
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