Elements of a Glovebox Glove Integrity Program
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RESEARCH ARTICLE Elements of a Glovebox Glove Integrity Program Programmatic operations at the Los Alamos National Laboratory Plutonium Facility involve working with various amounts of plutonium and other highly toxic, alpha-emitting materials. The spread of radiological contamination on surfaces and airborne contamination and excursions of contaminants into the operator’s breathing zone are prevented through the use of a variety of gloveboxes. The glovebox gloves are the weakest part of this engineering control. As a matter of good business practice, a team of glovebox experts from Los Alamos National Laboratory has been assembled to proactively investigate processes and procedures that minimize unplanned openings in the glovebox gloves, i.e., breaches and failures. Working together, they have developed the key elements of an efficient Glovebox Glove Integrity Program (GGIP). In the following report, the consequences of a glove failure or breach are identified, the acceptable risk is clarified, and elements needed to implement an efficient GGIP are discussed. By Michael E. Cournoyer, INTRODUCTION Through an integrated approach, Julio M. Castro, controls have been developed and Michelle B. Lee, Plutonium requires a high degree of implemented that come from input Cindy M. Lawton, confinement and continuous control from glovebox workers, scientists, Young Ho Park, measures in nuclear research labora- health physicists, statisticians, and phy- Roy Lee, tories because of its extremely low sical therapists. Working together, they Stephen Schreiber permissible body burden.1 Methods have developed an efficient Glovebox and equipment must be designed Glove Integrity Program (GGIP). toward the ultimate accomplishment Recent accomplishes of this team have 2–5 Michael E. Cournoyer, Ph.D. is of preventing any internal deposition been previously reported. In the fol- affiliated with Los Alamos National of plutonium in organs such as the lowing report, openings in gloves are Laboratory, Los Alamos, NM 87545, liver, even though such a degree of defined, the consequences of a glove USA (Tel.: 505 665 7616; fax: 505 665 control may often seem extreme. This failure or breach are identified, the 3657; e-mail: [email protected]). is in contrast with the control of acceptable risk clarified, and elements external radiation where some rea- needed to implement an efficient GGIP Julio M. Castro is affiliated with Los sonable fraction of permissible dose presented. Alamos National Laboratory, Los Ala- is expected. Inhalation is generally mos, NM 87545, USA. considered the most common mode of intake of plutonium for the nuclear DEFINITIONS Michelle B. Lee, Ph.D. is affiliated with facility worker. Uncontrolled releases Los Alamos National Laboratory, Los of plutonium usually result in some Glove failure an unplanned open- Alamos, NM 87545, USA. contamination of the atmosphere ing in a glove caused by degrada- nearthesiteofrelease,whetherthe tion of the mechanical properties of Cindy M. Lawton is affiliated with Los plutonium is in a liquid, solid, or gas- the material over time, e.g., expo- Alamos National Laboratory, Los Ala- eous state. To preclude uncontrolled sure to chemicals and nuclear mos, NM 87545, USA. release, gloveboxes are used to con- materials. The primary means of fine plutonium during laboratory minimizing glove failures are Young Ho Park, Ph.D. is affiliated with work. The glovebox is an ‘‘absolute through a robust glove inspection Mechanical Engineering Department, barrier’’ barrier, i.e., a sealed enclo- program and by controlling glove New Mexico State University, Las sure. A typical glovebox train is service life. Cruces, NM 88003, USA. shown in Figure 1. Glove breach is an unplanned open- The weakest link of this system is the ing in a glove caused by mechanical Roy Lee is affiliated with Los Alamos glovebox gloves (hereafter referred to as damage during operations, e.g., pene- National Laboratory, Los Alamos, NM gloves) themselves. They are easily tration with a sharp object; rotating 87545, USA. punctured, torn, cracked, will deterio- equipment, pinch points, thermal rate, and have selective permeability for sources, etc. The primary means of Stephen Schreiber is affiliated with Los various chemicals. Careful inspection minimizing breaches is through Alamos National Laboratory, Los Ala- of the gloves before each use is neces- administrative controls and over- mos, NM 87545, USA. sary. gloves. 4 ß Division of Chemical Health and Safety of the American Chemical Society 1871-5532/$32.00 Elsevier Inc. All rights reserved. doi:10.1016/j.jchas.2008.03.001 A break in a glove that results in plutonium penetration into the skin or internal deposition of plutonium in the lungs can lead to serious injury in the Figure 1. Typical glovebox train. form of cancer. Table 1. Open-Front Hood Limits 1. The glove is replaced before breach Radionuclide or failure occurs. Operation/material type 237Np 238Pu 239Pu 241Am 243Am 2. The radiological control technician Storage and stock solution (g) 5700 0.2400 60.0 1.200 20.0 (RCT) detects contamination dur- Simple wet operations (g) 570 0.0240 6.0 0.120 2.0 ing a routine survey. Normal operations (g) 57 0.0024 0.6 0.012 0.2 3. The glovebox worker discovers a Open powders (g) N/Aa N/Aa N/Aa N/Aa N/Aa breach or failure during a daily inspection. a N/A: not applicable. 4. The glovebox worker discovers a breach or failure while working in CONSEQUENCE OF A GLOVE FAILURE A break in a glove that results in the glovebox. OR BREACH plutonium penetration into the skin 5. The glovebox worker discovers a or internal deposition of plutonium breach or failure after completing A typical glove failure can result in in the lungs can lead to serious injury a task in the glovebox. This is worker exposure/contamination, in the form of cancer. Thus, the like- usually determined with the moni- waste generation, and work stoppage. lihood of a breach or failure must be tor next to the glovebox. Before work continues, the room con- kept to a minimum in order for the risk 6. The continuous air monitor (CAM) taining the glovebox with the failed of doing glovebox work to be kept at an alarms, this greatly increases the glove is usually shut down until it is acceptable level, as shown in Figure 2.7 likelihood of an uptake of pluto- cleaned up and recertified for opera- The sooner a breach or failure is nium into the lungs. tions. A simpler way of understanding discovered, the lower the severity. In 7. The glovebox worker discovers a this accident scenario is to realize increasing order of severity, a breach breach because his or her skin has that once a glove is ruptured, the or failure is detected during the follow- been penetrated resulting in a containment system is now only as ing task: bleeding wound. effective as an open-front hood. For review, the limits of radioactive mate- rial allowed in open-front hoods based on the amount of material used modified by the exposure adjustment are shown in Table 1.6 Clearly, no operations with open powders are acceptable. Glove breaches and failures do not usually result in radiological workers receiving a significant intake of radio- active material. Most glove breaches and failures result in alpha contamina- tion of protective clothing, the lab worker, or the immediate laboratory area (floor). Figure 2. Concept of controlling risk. Journal of Chemical Health & Safety, January/February 2009 5 In the past, the boundary between on the inside surface of each glove). the gloveport are subject to being acceptable and unacceptable risk was If a shortage of gloves exists, this breached from and object outside the discovery of a breach or failure at requirement can be suspended for the glovebox, e.g., a ladder or Dewar step 5. The current boundary is step 3. up to a year, provided that the glove flask. A properly plugged port Detecting a breach or failure before this passes the radiological, visual, and should have a stub glove and a glove is considered a noteworthy practice. dexterity inspection. A shortage of port cap installed. Removal of a cap Detecting an unplanned opening after gloves may occur when switching from a port that has been out of step 3 requires action by line manage- from one type of glove to another, service (plugged with a stub glove ment. e.g., leaded gloves to unleaded and a glove port cap) must be treated gloves. The glove manufactures as a radiological task, i.e., ‘‘hot job,’’ THE GLOVEBOX GLOVE INTEGRITY may need up to 6–12 months to similar to a glove change with RCT PROGRAM (GGIP) adjust their production cycles. coverage because plugged and Glove service life extensions An capped ports are not subject to rou- In the previous section, the reasons extension of glove service life is tine radiation monitoring or inspec- why breaches and failures must be allowed after a team comprised of tion. For capping round glove ports, minimized were clearly outlined. The a RCT and a glovebox subject matter solid plastic caps are recommended. program elements that are in place to expert (SME) performs an inspec- Expired gloves A glove that is past achieve this objective are presented.8 tion (A best practice adopted from its expiration date, and that has not Savannah River Site). A maximum had its service life extended is con- Glove inspections Daily inspections of four extensions is allowed. The sidered out of service and not used must be performed each day before glovebox SME must have the follow- without additional compensatory gloves are used. These include a ing qualifications: works in the glo- measures. Compensatory measures visual inspection and self-monitor- vebox on a regular basis; is familiar required for use of an expired glove ing for radiological contamination with the operations of the glovebox; include a pre-use inspection, a Radi- by operators.