Murray E. Moore

Aerosol collection of the (Bladewerx Corporation) breathing zone monitor and portable workplace monitor.

The Radiation Protection Group at the Los Alamos National Laboratory has a wind tunnel capable of measuring the aerosol collection efficiencies of air sampling devices. In the fall of 2005, the group received an internal Los Alamos request to perform aerosol collection efficiency tests on two air samplers manufactured by the Bladewerx Corporation (Rio Rancho, NM). This paper presents the results from tests performed in the wind tunnel facility at a test velocity of 0.5 m s−1. The SabreAlert (Portable Workplace Monitor) and the SabreBZM (Breathing Zone Monitor) are both designed to detect and measure the presence of alpha emitting isotopes in atmospheres. The SabreAlert was operated at two test air flow rates of 6 and 45 liters per minute (LPM), and the SabreBZM was operated at two test air flow rates of 3 and 19 LPM. The aerosol collection efficiencies of both samplers were evaluated with oleic acid (monodisperse) liquid droplet aerosols tagged with sodium fluorescein tracer. These test aerosols varied in size from about 2.3 to 17.2 microns (aerodynamic equivalent diameter). The SabreAlert was roughly 100% efficient in aerosol collection at a flow rate of 6 LPM, and had an aerodynamic cutpoint diameter of 11.3 microns at the 45 LPM flow rate. The SabreBZM had an aerodynamic cutpoint diameter of 6.7 microns at the 3 LPM flow rate, but the SabreBZM aerosol collection efficiency never exceeded 13.6% at the 19 LPM test flow rate condition.

Dynamic Radioactive Source for Evaluating and Demonstrating Time-dependent Performance of Continuous Air Monitors

AbstractEvaluation of continuous air monitors in the presence of a plutonium aerosol is time intensive, expensive, and requires a specialized facility. The Radiation Protection Services Group at Los Alamos National Laboratory has designed a Dynamic Radioactive Source, intended to replace plutonium aerosol challenge testing. The Dynamic Radioactive Source is small enough to be inserted into the sampler filter chamber of a typical continuous air monitor. Time-dependent radioactivity is introduced from electroplated sources for real-time testing of a continuous air monitor where a mechanical wristwatch motor rotates a mask above an alpha-emitting electroplated disk source. The mask is attached to the watch’s minute hand, and as it rotates, more of the underlying source is revealed. The measured alpha activity increases with time, simulating the arrival of airborne radioactive particulates at the air sampler inlet. The Dynamic Radioactive Source allows the temporal behavior of puff and chronic release conditions to be mimicked without the need for radioactive aerosols. The new system is configurable to different continuous air monitor designs and provides an in-house testing capability (benchtop compatible). It is a repeatable and reusable system and does not contaminate the tested air monitor. Test benefits include direct user control, realistic (plutonium) aerosol spectra, and iterative development of continuous air monitor alarm algorithms. Data obtained using the Dynamic Radioactive Source has been used to elucidate alarm algorithms and to compare the response time of two commercial continuous air monitors.

In-Place Filter Tester Instrument for Nuclear Material Containers.

AbstractA portable instrument was developed to determine filter clogging and container leakage of in-place nuclear material storage canisters. This paper describes the development of an in-place filter tester for determining the “as found” condition of unopened canisters. The U.S. Department of Energy uses several thousand canisters for nuclear material storage, and air filters in the canister lids allow gases to escape while maintaining an equilibrated pressure without release of radioactive contamination. Diagnosing the filter condition and canister integrity is important for ensuring worker and public safety. Customized canister interfaces were developed for suction clamping (during tests) to two of the canister types in use at Los Alamos National Laboratory. Experimental leakage scenarios included: O-rings fouled with dust, cracked O-rings, and loose canister lids. The prototype tester has a measurement range for air leakage rates from 8.2 × 10−4 mL s−1 up to 3.0 × 100 mL s−1. This is sufficient to measure a leak rate of 3.4 × 10−2 mL s−1, which is the Los Alamos helium leak criterion for post-drop tested canisters. The In-Place-Filter-Tester cannot measure to the lower value of the helium leak criterion for pre-drop tested canisters (1.0 × 10−5 mL s−1). However, helium leak testing requires canister disassembly, while the new in-place filter tester is able to assess the assembled condition of as-found and in-situ canisters.

End of FY2014 Report - Filter Measurement System for Nuclear Material Storage Canisters (Including Altitude Correction for Filter Pressure Drop)

Two LANL FTS (Filter Test System ) devices for nuclear material storage canisters are fully operational. One is located in PF-4 ( i.e. the TA-55 FTS) while the other is located at the Radiation Protection Division’s Aerosol Engineering Facility ( i.e. the TA-3 FTS). The systems are functionally equivalent , with the TA-3 FTS being the test-bed for new additions and for resolving any issues found in the TA-55 FTS. There is currently one unresolved issue regarding the TA-55 FTS device. The canister lid clamp does not give a leak tight seal when testing the 1 QT (quart) or 2 QT SAVY lids. An adapter plate is being developed that will ensure a correct test configuration when the 1 or 2 QT SAVY lid s are being tested .

SAVY-4000 Surveillance and Life Extension Program Fiscal Year 2013 Annual Report

The Packaging Surveillance Program section of the DOE M441.1-1/sup>1, Nuclear Material Packaging Manual (DOE, 2008) requires DOE contractors to “ensure that a surveillance program is established and implemented to ensure the nuclear material storage package continues to meet its design criteria.” In order to ensure continuing safe storage of nuclear material and the maximization of risk reduction, TA-55 has established a Surveillance Program to ensure storage container integrity for operations within its specified design life. The LANL SAVY-4000 Field Surveillance Plan2 defines the near-term field surveillance plan for SAVY-4000 containers as required by the Manual. A long-term surveillance plan will be established based on the results of the first several years of surveillance and the results of the lifetime extension studies as defined in the Accelerated Aging Plan3. This report details progress in positioning the Surveillance Program for successful implementation in FY14 and status of the Design Life Extension Program in terms of its implementation and data collection for FY13.

Determination of the internal exposure hazard from plutonium work in an open front hood

The particle size and quantity of a plutonium dioxide surrogate escaping an open front hood during routine work was measured. Aerosols were collected using a cascade impactor, and the amount of surrogate on each stage of the impactor was measured using neutron activation analysis. The aerodynamic mass median diameter of particles in the breathing zone of a worker was found to be 0.35 ± 5.1 &mgr;m. During a 2-h period when normal work activities were mimicked, an average of 3% of the material or 11.13 ± 0.54 &mgr;g escaped the hood. This was calculated to be equivalent to 10,000 ± 487 Bq (239Pu). The activity in the breathing zone of the worker is estimated, based on other research, to be 36 times less than this, or approximately 280 Bq. Worker occupancy factors were considered and a committed effective dose equivalent of 5 mSv was calculated. The cost-benefit analysis showed the use of the open front hood as a reasonable protective measure. Although worker exposure may approach the International Commission on Radiological Protection limit, the cost of the ergonomic injuries caused by work in a glove box is 5,000 times greater than the dose received by the worker. Protective measures such as respiratory protection should be evaluated on a case by case basis to keep worker exposure as low as reasonably achievable.