United States Nuclear Regulatory Commission - Protecting People and the Environment

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)

Purpose:

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 
Part 21.  

Discussion:

                 Background -

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 
          changes.

     -    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.

                                        Sincerely,




                                        Richard L. Bangart, Director 
                                        Division of Low-Level Waste 
                                        Management and Decommissioning, 
                                        NMSS

Technical Contact:  Michael Tokar, NMSS 
                    (301) 492-0590 

Enclosure:
List of Recently Issued Generic Letters

Page Last Reviewed/Updated Friday, June 28, 2013