Re: Silica Products - Path Forward RequiredFrom: Jerry D. Levine Sent: Monday, December 12, 2005 10:51 AM To: Geoffrey J. Gettelfinger Cc: Paul Goranson; Bradley E. Nelson; Wayne T. Reiersen; Erik D. Perry; William V. Slavin Subject: Re: Silica Products - Path Forward Required Geoff, I will let Bill address the dust hazard issues you have raised. You may also be aware of other questions/issues that have been raised about nanogel which include: 1. The MSDS for this product indicates in several places that temperatures above 250°C should be avoided (possibly because “heating can release vapors which can be ignited”). The NCSX GRD (Section 3.2.1.2.3) states that “The temperature of the vacuum vessel shell will be capable of being elevated to a nominal temperature of 150ºC for vacuum vessel bakeout operations and to a nominal temperature of 350ºC to support bakeout of an in-vessel carbon based liner (to be installed as an upgrade) at that temperature.” How will the temperature of the aerogel beads be limited to <250°C when the vessel shell is baked out to 350ºC? 2. I don’t think this is an issue, but a check should be made on the radiation properties of this product, e.g., any degradation under NCSX radiation conditions, neutron activation potential, etc. 3. Areas which have aerogel beads will need to have all metal parts grounded, welding will need to be prohibited and explosion proof electrical systems will need to be considered. Preventing release of this material to the environment will be an issue and exposure to personnel will need to be addressed. Item #1 is being addressed by plans to remove the Nanogel beads that will be exposed to high heat before instituting the 350ºC bakeout upgrade. I have some concerns about the practicality of this and have recommended a design review for this concept. I support your idea for a Project position on the VV thermal insulation and would like to see it encompass the above issues as well. Jerry On 12/12/05 10:21 AM, "Geoffrey J. Gettelfinger" wrote: Bill/Jerry: I feel the NCSX Project and the PPPL/ORNL parent organizations need to come to a fully-considered position on the industrial hygiene aspects of the various thermal insulation materials that are being considered. A summary memo from the Project (including you fellows as Project stakeholders) should probably be generated so we can refer back to it as questions arise. Problem Statement: Loose gas-filled thermal insulation is required in the variable geometry "annulus" between the vacuum vessel and the modular coils. Separately, space constraints in the cryostat design may drive the Project in the direction of gas-filled insulation as well. Candidate insulations are silica aerogel and perlite. Using word association, one might relate the word "silica" with "silicosis" which could raise concern the minds of some. There is also a proposed use of silica aerogel in a blanket format which, while dusty, does not qualify as "loose" fill. Perlite is not without its own suggestive wording: It is primarily "fused sodium potassium aluminum silicate". A laymen's interpretation of the MSDS content for the above products quickly finds phrases like "nuisance dust hazard" and "non-carcinogenic". The layman assumes we can bathe in these products as long as we wear some ill-fitting discount store dust mask. The MSDS for silica-containing Portland cement, for comparison, uses phrases such as "carcinogenic". The Project will likely use many cubic feet of loose fill and *any* well-designed system will have some leaks because of the products' fine particle sizes. 1. How do we proactively assess how diligent we must be during NCSX construction and subsequent operate-modify-operate cycles to protect test cell accessors from the dust hazard? 2. Are shop vacuums acceptable or are HEPA units required? 3. What grade of dust masks will be required for our workers (fit checks, medical evals, etc.)? 4. **Are we allowed to accept MSDS’s as accurate?** I strongly suspect that I am over-agonizing on these themes but, at least until the Project signs off on a position, this remains an open item. Please advise, informally or by e-mail, on any path forward you feel is appropriate. Some links for those copied follow: MSDS for Portland cement: http://www.vincistone.com/library/msds_lehigh_masonry_cement.htm MSDS for loose perlite: http://www.schundler.com/msdsperl.htm MSDS for loose aerogel: http://www.aerogel.com/pdfs/msdsspaceloftar3100.pdf On the topic of silicosis: http://www.nlm.nih.gov/medlineplus/ency/article/000134.htm Thanks, Geoff Jerry D. Levine Head, Environment, Safety & Health (ES&H) DOE Princeton Plasma Physics Laboratory P.O. Box 451 Princeton, New Jersey 08543 C-Site, Module 6, Room 104, MS01 Phone: 609-243-3439 Lab Pager #340 Skypager Pin # 1335520 Fax: 609-243-2525 You can visit the home page of the DOE Princeton Plasma Physics Laboratory at http://www.pppl.gov