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Lessons Learned from Extremity Exposure Event on July 24, 2009. C. John Graham LANSCE ESH&Q Manager 2010 Accelerator Safety Workshop LA-UR 10-05375. LANSCE presently provides the US and international research communities a diverse set of premier facilities. Lujan Center
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Lessons Learned from Extremity Exposure Event on July 24, 2009 C. John Graham LANSCE ESH&Q Manager 2010 Accelerator Safety Workshop LA-UR 10-05375
LANSCE presently provides the US and international research communities a diverse set of premier facilities • Lujan Center • Materials science and condensed matter research • Bio-science • Nuclear physics • A National BES user facility • WNR • Nuclear physics • Semiconductor irradiation • Ultra-cold Neutron Facility • Fundamental nuclear physics • Proton Radiography • HE science, dynamic materials science, hydrodynamics • Isotope Production Facility • Nuclear medicine and research isotope production Beam delivery to multiple facilities 6 mo/yr @ 24/7 with ~ 1200 user visits
Background 73/74As sample produced at LANSCE IPF and processed at TA-48 chemistry hot cells For WNR experiment to measure the 74As(n,p) cross section at low incident neutron energies using the lead slowing-down spectrometer in the Blue Room Sample material material dried onto titanium backing and covered with thin Ti window 74As is a beta emitter Dose rate of 2-5 R/hr was expected
What happened • Original plan was to mount sample in an ion chamber at WNR within a glove box to contain any contamination • RWP prepared with 5 R/hr dose rate limit; glove box expected to mitigate beta hazard • TA-48 dose rate readings of 500 mR/hr and 30 R/hr communicated to C-NR researcher at TA-53 • Conversation was about ability to ship to TA-53 • TA-48 RCT left voice mail for RP-1 at TA-53; no dose rate detail • Sample received at MPF-541 trailer by C-NR researcher and surveyed by day shift RCT • No contamination detected on inside of shipping container (lead pig) • Survey tag from TA-48 indicated 500K dpm contamination • External dose rate at 30 cm was 5 R/hr β+γ (1 R/hr γ)
What happened • RP-1 did not perform shallow (beta) dose calculation • RCT had only performed calculation for beam line components, not for experiment sample receipt (former is common, latter is not) • Assumption of glove box use and further HP review • Extremity dosimetry not required by RWP • Assumed use of glovebox • Workers were wearing EPDs • Researcher and RCTs discussed dose rate readings and sample mounting • Researcher thought RP-1 knew that sample was to be mounted outside glove box in WNR Blue Room entrance maze • Research team broke for dinner
What happened • RCT shift change; new RCT not aware of TA-48 dose rate measurements or significant beta component • Prejob meeting held • Researchers discussed rationale for mounting sample outside of glove box with new RCT • No contamination found in receipt survey; less time for sample mounting (ALARA) • RCT agreed, though change was outside of RWP • Sample transferred in pig from MPF-541 to Blue Room entrance hallway • Sample not re-surveyed outside of pig; new RCT thought previous surveys were adequate
C-NR researcher and LANSCE-NS researcher mounted sample in the ion chamber Used tweezers but fingers were needed to push sample into place RCT performed dose rate surveys (4 R/hr @ 30 cm; 115 mR/hr behind work area shielding) RCT measured 30 R/hr dose rate as ion chamber assembly was being completed What happened target source spacers cover
What happened Work paused Situation safed by placing cover on ion chamber RP-1 HP consulted and agreed that completing assembly and installing sample in LSDS ensured a safe configuration Concern reported to TA-53 management 1 week later
What went wrong? • Some things were done right, e.g. pauses in work, considering ALARA, safeing the situation • Imprecise communications • Generic IWD for LSDS but no IWD for this sample • Experiment screening by LANSCE-NS was “low hazard” based on early information that sample mounting would be done at TA-48 • Work plan changed without adequate communication between research team and RP-1; RWP work description did not reflect the actual work; led to inconsistent understanding of hazards and insufficient controls • TA-48 RCT left voice mail for TA-53 RP-1 • Informal RCT shift turnover • RP-1 did not recognize need for a shallow dose calculation • Infrequent/unfamiliar activity
What went wrong? • Improper assumptions and decision making • Sample assumed not significantly contaminated based on indirect surveys of shipping container—reinforced decision to not use glove box • RCT coming on shift assumed previous surveys were adequate • RCT concurred with working outside RWP • Hands-on work with sample continued without resolving discrepant dose readings at TA-48
Consequences • Two persons at TA-53 received extremity doses of 26 and 19 rem, respectively • Based on dose reconstruction by RP • Below the DOE limit of 50 rem but unplanned and unmonitored (no extremity dosimeters) • ORPS reportable category 2, PAAA noncompliance report • DOE enforcement action and civil penalty possible • One of several incidents related to R&D work control at the Lab
Lessons learned • ISM core function 1 (define work) is pivotal to identification of hazards and appropriate controls. • Unique or first-time hazardous work involving multiple organizations and disciplines requires teamwork, critical thinking, professional expertise, and rigor in communication and work control. • Follow work control documents. Changes (including inconsistent hazard information or real-time indicators) that affect hazard levels, controls, or assumptions about work execution warrant a pause, re-evaluation, and appropriate change control.
Lessons learned • Criteria for minor field changes to RWPs vs. major changes that require reauthorization of the work must be communicated and understood by personnel responsible for directing work activities. • Communication among SMEs and between SMEs and organizations performing work must be clear and frequent enough to ensure that the scope of work is well understood. SMEs should be engaged to help resolve inconsistent hazard information.
Lessons learned • Real-time information should be shared through direct communication across facilities and organizations. Information transfer by documentation is not a substitute for direct interactive communication. • Use of the revised P&T Form 2114 “Hazard Communication for Radioactive Material Shipments” will help ensure that those who unpack these materials, as well as support/oversight organizations, are informed of the nature of the packaging and associated hazards.
Lessons learned • When interdependent work processes take place in multiple facilities or organizations, work control documents should be coordinated or crosschecked to ensure consistency and comprehensiveness. • SMEs must be provided with tools to enable critical thinking with respect to hazards that are expected but not routinely encountered. • Complex or high hazard activities should be given priority for scheduling during normal working hours when management and support resources are available.