Mylar Protective Coatings for Glovebox, Shielded Cells, and ...

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American Glovebox Society
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Volume 23 #1 – 2010
Mylar Protective Coatings for Glovebox,
Shielded Cells, and Chemical Hood Windows
By: David Peeler, Savannah River National Laboratory and Lyle Freeman. Premier Technology, Inc. – page 6
AGS Conference & Expo 2010on pages 18 &19

In This Issue...
Mylar Protective
Coatings for Glovebox,
Shielded Cells, and
Chemical Hood Windows
By: David Peeler, Savannah River National
Laboratory and Lyle Freeman. Premier
Technology, Inc. . . . . . . . . . . . . . . . . . . . . . .6
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The Enclosure
Volume 23, Number 1
Editor
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Publisher
American Glovebox Society
The Enclosure is published for the benefit of
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Mylar Protective Coatings for
Glovebox, Shielded Cells,
and Chemical Hood Windows
By: David Peeler, Savannah River National Laboratory. Aiken, South Carolina and
Lyle Freeman. Premier Technology, Inc., Blackfoot, Idaho
6
INTRODUCTION
Acommon issue for isolator (gloveboxes, shielded cells, chemical hoods, etc.) windows is the
degradation of visual clarity over time due to accidental scratching, spills, splatters,
staining, and/or radiation damage. As visual clarity degrades, operational efficiency also
decreases as operators have increased difficulty in performing routine tasks. At some point, a
decision is made to either replace or refurbish the affected window, which can be time
consuming and costly as well as lead to significant operational downtime. As an example, a
current technique to mitigate this issue used in the Savannah River National Laboratory (SRNL)
Shielded Cells is to place a rigid, monolithic sheet of Lexan (typically 40” (length) x 36” (width)
x 1/2” (thick)) in front of the glass window as a protective barrier. Over time, visual clarity of the
Lexan deteriorates, resulting in the need to replace the Lexan sheet every 1 to 2 years or on
an as-needed basis. Replacement is accomplished by cutting a new Lexan sheet to size,
retrofitting this sheet with manipulator friendly handles, transferring the sheet into the cells, and
mounting the sheet into place. Subsequently, the worn Lexan sheet is cut into smaller pieces
and disposed of via the appropriate waste disposal route. Similar degradation occurs on
glovebox or hood sash windows, but in these cases complete replacement of the window is
typically required to regain visual clarity (i.e., generally no primary barrier is used). Whether it
is the replacement of a large Lexan sheet in the SRNL Shielded Cells or a direct replacement
of a window in a shielded cell, glovebox, or hood sash, replacement and bulk waste disposal
are required, which can be time consuming and costly.
SRNL has introduced a unique and novel system to overcome the difficulties of this work
environment. A series of tests were conducted at SRNL to assess the use of a thin, multilayered
system of Mylar sheets (each sheet approximately 4 mil thick) to serve as a primary or
secondary protective barrier against acid etching (“frosting”), accidental scratching (e.g., by
manipulator or tool contact), accidental spills or splashes (e.g., acids and/or bases), and/or
radiation damage for isolator or enclosure windows. Thin, multi-layered sheets of Mylar
(referred to as the ProTec tear-off system) directly applied to the Lexan sheet or window could
result in significant cost reductions through rapid restoration of visual clarity leading to minimal
degradation in operator efficiency and overall facility attainment. Upon degradation of visual
clarity due to accidental scratching, spills/splatters, and/or radiation damage, the outer layer
(or sheet) of Mylar can be removed restoring visual clarity. Due to the multiple layers, the
remaining Mylar sheets would provide continued protection for the window from potential
reoccurrences (which could be immediate or after some extended time period).
As mentioned, a significant advantage of this system is that it reduces the waste disposal
volume (i.e., disposal of a thin 4 mil thick sheet of Mylar, which is collapsible, versus the bulk
disposal of a rigid Lexan sheet or a glovebox/sash window that may require size reduction to
fit disposal containment). The multi-layer ProTec tear-off system would also reduce the
number of cell entries needed to replace the Lexan or alpha shields and increase the time
interval between glovebox/sash window replacements which are costly and time consuming.
OBJECTIVE AND METRICS
The objective of this study was to demonstrate the viability of the Mylar tear-off system to
serve as an effective primary or secondary barrier against damage incurred as a result of
radiation, acidic/basic reactions, and/or accidental scratching. In addition, in-situ testing was
performed to gain insight into the system’s performance under very harsh environmental and
test conditions.
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continued from page 6
Mylar Protective Coatings for Glovebox, Shielded Cells,
and Chemical Hood Windows
Two primary metrics were used to judge whether the
ProTec tear-off system could be successfully implemented into
these hazardous environments:
• Mechanical integrity
• Visual clarity
The metric of mechanical integrity is rather straightforward
in terms of classifying success. If the outermost tear-off can not
be completely removed by the use of manipulators (or by hand
in other applications such as glovebox or hood sash use) after
exposure to some environment, then the tear-off system or
concept is of no value. Complete removal (i.e. without ripping)
of the outer layer tear-off after exposure to acids, bases,
physical impact, radiation or any combination of these is of
utmost importance.
With respect to visual clarity, the success metric becomes
a little more ill-defined. That is, documentation via notebook
entries and time-lapsed digital photos can provide a visual
measure from which to gauge success, but what level of visual
degradation would result in a decision to terminate the possible
implementation of the concept? The answer may rely not on
how much visual degradation occurs, but on how long it takes
to reach some critical or detrimental level. As previously
mentioned, current practice in the SRNL Shielded Cells requires
changing the Lexan sheets or alpha shields that protect the
primary window on some time interval basis (typically 1 to 2
years). If the tear-offs extend this time interval, one may classify
this as a success. In judging this potential, one also has to
remember that the tear-offs are multi-layered, so visual degradation
success should perhaps be judged on the integrated time
the ProTec tear-off system provides access to visual clarity
relative to the 1-2 year time period typically observed for each
Lexan plate.
EXPERIMENTAL APPROACH AND RESULT
To assess the viability of the tear-off system as a protective
barrier, a series of tests was conducted to evaluate the performance
of the system under specific environmental conditions.
The environmental or test conditions used to demonstrate
viability included:
8
• acid/base resistance (e.g., simulating exposure to acid
vapors or base spills/splatters),
• scratch resistance (e.g., an aggressive simulation of
accidental contact between the window and the
manipulator and/or other tools),
• radiation damage resistance (e.g., against radioactive
sources in shielded cells and/or gloveboxes),
• in-situ service conditions of a tear-off prototype within
the analytical cells of the world’s largest high-level
waste vitrification facility (the Defense Waste Processing
Facility (DWPF)).
Long-term exposure to four acids covered a time of 456
days. Base resistance testing utilized a simulated DWPF highlevel
waste sludge with a pH of approximately 13. In addition,
two in-situ demonstrations were performed to gain some insight
into the behavior of the Mylar tear-off system under more realis-
tic service conditions. One in-situ test occurred in the SRNL
Shielded Cells Facility in which the Mylar tear-off system was
exposed to gamma radiation for ~700 days (or a cumulative
dose of ~3.4 x 10 5 rad) and other in-cell environmental
conditions which varied as different projects were completed. A
Mylar tear-off prototype was also inserted into actual radioactive
field conditions within DWPF’s Analytical Sampling Cells. During
the in-situ testing, the tear-off systems were exposed to acidic
environments (vapor and contact), radioactive backgrounds (as
actual high-level waste was sampled and processed), and
manipulator contact over a 5 to 6 month period. A high-level
overview of the test conditions and results are discussed below.
George et al. (2005) and Peeler (2008) provide a full description
of the experimental tests, their basis, and the results.
ACID RESISTANCE
To support this assessment, a set of 4 mil (3 layer) Mylar
tear-offs was mounted on four separate Lexan plates. Each
Lexan plate was placed directly on top of a Teflon vessel
(referred to as a 0” height) containing one of four acids
exposing the Mylar tear-off to the acid vapors. Figure 1 shows
the set-up of three of the four acid resistance tests. As specified
by the DWPF, the acids and concentrations used were: concentrated
(28.9M) HF, concentrated (15.9M) HNO3, 6M HCl, and
0.6M H3BO3. The Teflon vessels had a capacity of 250 mL and
were filled and maintained with approximately 200 – 225 mL of
acid. In addition to the tear-off system (Lexan + tear-off), a Lexan
blank (Lexan-only) was also placed on top of each acid bath as
a reference (simulating the SRNL Shielded Cells or DWPF
Analytical Sampling Cells use as the primary barrier). The Lexan
blanks provided a baseline measure of how aggressive the
specific test conditions (acid type and/or acid molarity) were
with respect to historical observations. For example, a test
condition in which the Lexan blank begins to lose visual clarity
within a short-time frame may be indicative of an overly aggressive
condition compared to those observed in actual field
situations. Additionally, the blanks provide a basis for each test
condition when comparing the blank with that of the Lexan with
tear-off system.
Conc HF
0.6 H 3BO 3
6M HCI
Figure 1. Experimental set-up for acid resistance testing (0” height).
(Note that the concentrated HNO3 test was performed in a
separate hood for safety reasons).
continued on page 10

10
continued from page 8
Mylar Protective Coatings for Glovebox,
Shielded Cells, and Chemical Hood Windows
The acid resistance testing was terminated after 456 days with three significant
findings. The first occurred on Day 35 with the formation of a yellow stain on the
Lexan blank exposed to the concentrated HNO3. This result suggests that the 0”
height being used in this testing is relatively aggressive given that in actual service
conditions in the DWPF Analytical Sampling Cells, visual distortion is not observed
within this short of a timeframe. The fact that the HNO3 tests did not induce a
reaction or visual distortion on the Mylar tear-off indicates that the tear-off should
add service life to the Lexan plate or provide a layer of protection to the primary
window under these test conditions.
The second major observation was the formation of a yellow stain on the Mylar
tear-off after 314 days of exposure to concentrated HNO3. No other reactions or
visual distortions were observed on the other tear-offs exposed to concentrated
(28.9M) HF, 6M HCl, and 0.6M H3BO3. Although there was an apparent reaction
between the Mylar tear-off and the HNO3 vapors after 314 days, complete removal
of the outer layer tear-off was achieved restoring visual clarity. Restoration of visual
clarity indicated that the yellow stain was only associated with the outer layer tearoff
and did not penetrate through to the remaining two layers.
The third major finding was that regardless of the test condition (type of acid
and concentration), the outer layer tear-off was easily removed suggesting no loss
of mechanical integrity after extended and aggressive exposure to acidic vapors.
Figures 2 and 3 provide pre-removal and post-removal photographs of the 6M HCl
tear-off system after 456 days. In Figure 2, “reaction rings” are observed where the
tear-off system rested on the 6M HCl Teflon vessel. The rings could be a result of a
reaction of the Mylar tear-off with the HCl vapors and/or surface roughness (small
scratches) from contact with the plastic acid vessel. Figure 3 shows the post-removal
condition of this system where the “rings” have been removed and visual clarity has
been restored – which is the primary objective of the tear-off system.
These results suggest that the ProTec tear-offs are a viable system capable of
withstanding relatively aggressive vapor attack from these specific acids, while
offering the opportunity to restore visual clarity through the removal of the outer
layer tear-off when needed. The fact that the tear-offs were exposed for 456 days
suggests that (at a minimum) the Lexan sheets currently used by the SRNL Shielded
Cells and DWPF Analytical Sampling Cells (which are replaced every 1-2 years)
could have an increased service life (3-4 times) when enhanced by a multi-layer
ProTec tear-off system.
Figure 2. Pre-removal condition of the 6M HCl ProTec tear-off system (456 days at 0”).
continued on page 12

continued from page 10 Mylar Protective Coatings for Glovebox, Shielded Cells,
and Chemical Hood Windows
Figure 3. Post-removal of the outer ProTec tear-off from the 6M
HCl system (456 days at 0”- reflection of laboratory light is visible
near center of tear-off).
BASE RESISTANCE TESTING
To assess the resistance of the tear-offs to highly basic
materials, a simulated DWPF high-level waste sludge with a
starting pH of 12.9 was splattered onto the tear-off and allowed
to dry for 24 hours. Figure 4 shows the dried simulated sludge
on the Lexan blank (left) and on the tear-off (right). In an attempt
to clean the dried sludge from both the Lexan plate and tear-off,
deionized water and a wipe were used. The result smeared the
sludge across both surfaces leaving a residue which quickly
dried – distorting visual clarity. According to DWPF Analytical
Sampling Cell personnel, this was a very good approximation of
an attempt to clean a splatter of high-level waste sludge onto
the shielded cell window.
Figure 5 shows the system after removal of the outer layer
tear-off. The outer tear-off is shown on the right (note that the
residual sludge is only on half of the tear-off due to its original
placement). The residual dried sludge that was removed with
the tear-off is also clearly seen in Figure 5. Upon removal of the
outer tear-off, visual clarity was restored to the tear-off system
as compared to the sludge residue left on the Lexan blank.
Upon visual inspection of the tear-off, no visual signs of aggressive
chemical interaction (i.e., pitting or holes) were observed
on the Mylar tear-off. The two tear-offs remaining serve as the
next layers of defense and protection for the subsequent event.
The results indicate that the ProTec tear-off system is also
impervious to high pH materials under these test conditions.
12
Figure 4. Dried simulated sludge on the Lexan blank (left) and the
Mylar tear-off (right).
Figure 5. Restored visual clarity of the tear-off system (left, upper
portion) via removal of the outer layer tear-off (right).
SCRATCH RESISTANCE TESTING
Under service conditions, a primary potential for physical
damage to the tear-offs is accidental scratching. For example, in
a shielded cells application, manipulators (or other materials
such as a tool or vessel being held by the manipulator) could
contact the tear-off system inducing scratches or marks which
over time could severely impair visual clarity. It should be noted
that the use of the terminology of “scratch resistance” is
somewhat of a misnomer given Mylar is susceptible to scratching
or residual markings. Having said that, the purpose of the
multiple Mylar tear-off system is to prevent damage to the
underlying Mylar layers or shielded cell, glovebox, or sash
window to the extent that upon removal of the outer tear-off, the
scratches or marks would be removed (conceptually erasing or
clearing any visual obstructions) while providing the next layer
of protection.
To address this issue, a Lexan blank and a tear-off system
were placed into the SRNL Shielded Cells mock-up facility (see
Figure 6). A single sheet of Lexan (~10” length x 10” width x
1/2” thick) was used with a multi-layered tear-off system
continued on page 14

continued from page 12
Figure 6. Lexan plate with mounted tear-off prior to scratch
resistance testing.
mounted on one side of the Lexan (right hand side of Figure 6).
A modified tab (lower right in Figure 6) was placed on the three
individual tear-off sheets to allow the manipulators to grab the
outer layer tear-off to assess removal potential (i.e., mechanical
integrity) after physical damage had been induced.
The plate was mounted in the SRNL mock-up facility where
the manipulators were then used to test the scratch resistance
via simulating accidental scraping/scratching of the window.
With respect to the physical nature of the tests (i.e., the
magnitude and frequency of manipulator contact with the blank
or tear-offs), there were no official guidelines or procedures to
govern this effort – given contact is accidental. That is, to what
degree should the shielded cells technician abuse the tear-offs
with the manipulator to assess scratch resistance? Given no set
rules, the test was performed using what was considered to be
a bounding approach from a shielded cells personnel perspective.
That is, the degree or severity of interaction was rather
excessive to simulate a long-term service or exposure which
would yield multiple contacts. For example, the shielded cells
technician intentionally induced scratches on the surfaces of
both the Lexan blank and tear-off system using a force and/or
frequency that were inconsistent with normal manipulator
operations in the shielded cells. In this test, the manipulator (or
manipulator tip or grips) was used as both a hammer (beating
the Lexan blank and tear-off system in an attempt to puncture
the Mylar) and as a scraper (intentionally running the manipulator
grips up-and-down the face of the Lexan sheet transitioning
back-and-forth between the blank to the tear-off systems
inducing marks/scrapes along the way). Although excessive
force and somewhat unrealistic service conditions were used,
the primary interest was the mechanical integrity of the tear-off
system after inducing the scratches and the ability to erase the
visual degradation upon removal of the outer layer Mylar sheet.
Figure 7 shows the results of the intentional abuse to the
Lexan blank and tear-off system. Scratches and marks are very
apparent on both the tear-off and Lexan blank and were
considered consistent with (or at least similar to) those
observed in actual service based on SRNL Shielded Cells
personnel observations.
Figure 8 shows the same system after removal of the outer
layer tear-off with the manipulators. The marks and scratches on
14
Mylar Protective Coatings for Glovebox, Shielded Cells,
and Chemical Hood Windows
the Mylar tear-off system have been removed refreshing visual
clarity as conceptually intended. Measures of the degree of
restoration of visual clarity are the reflection of the bottle on the
upper portion of the system and the absence of vertical
marks/scratches. Another important observation upon completion
of this test was the absence of damage (tears, holes, pits)
to the underlying layers of the multi-layer tear-off system. The
results of this test clearly demonstrate the robustness of the
Mylar tear-off system to withstand aggressive physical abuse
without compromising mechanical integrity. Removal of the
outer layer tear-off in this test not only restored visual clarity but
also served as the initial demonstration of the ability to remove
the single outer layer sheet with the manipulator which
preserves the multi-layer aspect of this concept. Successful
removal of the outer Mylar tear-off under mock-up conditions
provided a sound technical basis for conducting such tests
remotely under actual service conditions.
Figure 7. Lexan blank and tear-off system after manipulator
interaction.
Figure 8. Lexan blank and tear-off systems after removal
of outer layer.
continued on next page

continued from previous page
RADIATION EXPOSURE
To assess potential impacts of radiation on the Mylar tearoffs,
a Lexan plate with a tear-off system mounted on one side
was inserted into Cell #15 in the SRNL Shielded Cells. Cell #15
was selected due to the high gamma background emitted from
Co-60 sources (Bibler 2005). The Lexan plate was placed in
Cell #15 on July 28, 2005 and was monitored for visual clarity
on a routine basis. Figure 9 shows the Lexan plate and tear-off
system hanging from an intermediate wall in Cell #15 just after
cell entry. The Mylar tear-off system is visible on the right side
of the Lexan plate, which is aligned vertically.
On September 12, 2005 (after 46 days of exposure or
~22,000 rad gamma cumulative dose) the outer layer tear-off
was removed with the manipulators to assess both mechanical
integrity and ease of removal with the manipulators. The outer
layer was completely removed indicating no embrittlement of the
Mylar after the 46 day exposure. After the removal of the outer
layer, the Lexan sheet was placed back on the wall in Cell #15
(with two tear-offs remaining) to support longer term testing.
Figure 9. Lexan plate with tear-off system (right) introduced into
Cell #15 on July 28, 2005 (day 1).
On June 20, 2006, the second tear-off was removed after
328 days of exposure (~157,000 rad). Prior to removal of the
outer layer (the 2 nd of three layers), no visual degradation was
noted. The outer layer was easily and completely removed (i.e.
without ripping) with the manipulators – consistent with the
removal of the first layer. After removal of the second layer, there
was a noticeable distinction between the “fresh” tear-off and the
Lexan blank in terms of visual clarity. Figure 10 shows the system
just after removal of the outer layer tear-off. On the right hand
side, the reflection of the pipettes or small sample bottles is
relatively sharp as compared to the more diffuse Lexan “ blank
side. This result suggests that some type of residue was coating
the entire system (not evident prior to removal) and upon
removal of the tear-off, the deposited layer was removed which
could have led to visual distortion over time.
Figure 10. Post-removal of the outer ProTec tear-off layer after
328 days of exposure (~157,000 rad – note reflections of pipettes
or small sample bottles across bottom half of plate).
On June 26, 2007, after approximately 700 days of service
and an estimated 336,000 rad exposure, the third and final
tear-off was removed. Prior to removal, there were no visual
signs of degradation (see Figure 11). However, as observed with
continued on next page
15

continued from previous page
the 328 day test, upon removal there did appear to be a coating
or deposit on the final tear-off (see Figure 12). This is evident by
the clean area formed by the outline of where the tear-off
system was located.
Figure 11. Pre-removal of the final tear-off layer after approximately
700 Days of Exposure (~336,000 rad) on June 26, 2007.
Figure 12. Post-removal of the Final Tear-Off Layer after approximately
700 Days of Exposure (~336,000 rad) on June 26, 2007.
(A coating or deposit is present on the left side of the plate while
the area outlined by the previous location of the tear-off system
is clean).
DWPF SAMPLING CELLS IN-SITU TESTING
The in-situ DWPF Analytical Sampling Cell demonstration
was initiated to provide additional insight into the potential use
of the ProTec tear-off system under realistic service conditions.
Under these tests, the Mylar tear-offs would be exposed to
extremely high radiation fields (the source being high-level
waste sludge being sampled and processed through the cell) as
well as exposure to other vapors and air-borne particulates
under prototypic service conditions (not a controlled environment
but actual field conditions). On January 12, 2006, DWPF
installed one 12” length x 12” width x 1/2” thick Lexan plate in
Sampling Cell #2 and one 12” length x 12” width x 1/2” thick
Lexan plate in Sampling Cell #3. A ProTec tear-off system (a 3layered
system) was mounted onto each Lexan plate prior to
cell entry. The Lexan plates with tear-off systems were very
similar to those used in the SRNL Cell #15 testing described in
the previous section.
16
Sampling Cell #2 exposed the tear-off system to waste
cleaning activities, which involved leaching materials (bottles,
wipes, slurries, etc.) in 50% nitric acid solution followed by
water rinses. Waste cleaning activities are performed in this cell
to reduce the amount of transuranic (TRU) waste generated.
Sampling Cell #3 was selected due to the high volume of
sampling of the high-level waste and recycle condensate
materials in a high radiation background coupled with high pH
liquid/vapor exposure. The materials being sampled and
solutions used to clean in both cells are primary sources of the
window etching and frosting routinely experienced in DWPF
under normal operating conditions. DWPF does use a Lexan
alpha shield to help minimize etching or frosting; however,
recent experience has indicated that within 1 year of replacement,
visual clarity is distorted to the point where routine
operations become less efficient.
The DWPF in-situ testing was performed over a period of
approximately 6 months. During this time period, the tear-off
systems were exposed to various acidic fumes, radioactive
sludge, and various cleaning solutions. The Sampling Cell #3 tearoff
system was also rinsed with water and acid after each
sampling activity or if sludge material came into contact with the
tear-off system. As visibility became an issue, the ProTec tearoffs
were visually evaluated and the outer layer was removed
using manipulators.
After 105 days of service, the initial outer layer tear-off on
both systems was removed using manipulators. Complete
removal of the outer layer tear-offs was achieved (consistent
with the removal of those systems exposed to gamma radiation
in the SRNL Shielded Cell testing and in mock-up). The removal
of the 2 nd and 3 rd layers over a 6 month period also resulted in
complete removal which provides additional data on the viability
of the tear-off system under actual field conditions.
Cook (2006) provided a summary of the test conditions
and the results of the DWPF in-situ testing. An excerpt from that
report stated that “the Mylar layer was able to be removed
effortlessly with the manipulators.” The conclusions drawn from
DWPF personnel indicated that “the ProTec sheet will prolong
the lifetime of the alpha shields and provide good visibility for
personnel. Use of (unprotected) Lexan plates to protect the
alpha shields proved to be ineffective due to the corrosive
environment and the dry powder residue.”
Summary
A common issue for isolator (gloveboxes, shielded cells,
chemical hoods, etc.) windows is the degradation of visual
clarity over time due to accidental scratching, spills, splatters,
staining, and/or radiation damage. As visual clarity degrades,
operational efficiency also decreases as operators have
increased issues with performing routine tasks. At some point, a
decision is made to either replace or refurbish the affected
window which can be time consuming and costly as well as lead
to significant operational downtime. SRNL, with support from
Premier Technology, has completed a series of tests to assess
the potential use of a Mylar tear-off system as a primary or
secondary protective barrier to minimize acid etching
(“frosting”), accidental scratching, and/or radiation damage for
shielded cells, glovebox, and chemical hood windows. The
product consists of thin, multi-layered sheets of Mylar which can
be directly applied to the shielded cell, glovebox, or hood sash
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window to serve as a secondary (or primary) barrier. Upon
degradation of visual clarity due to accidental scratching,
spills/splatters, and/or radiation damage, the outer layer (or sheet)
of Mylar can be removed, restoring visual clarity. Due to the multilayer
aspect, the remaining Mylar layers would provide continued
protection for the window from potential reoccurrences (which
could be immediate or after some extended time period).
The results of this study clearly indicate that the tear-off
system is a viable technical solution to mitigate excessive
window damage that would result from acid etching or spills,
base damage (as a result of a sludge spill or splatter), gamma
radiation damage, and/or accidental scratching (due to manipulator/tool
contact).
With respect to acid resistance testing, no visual or physical
degradation was observed on the tear-off systems when
exposed to concentrated HF, concentrated HNO3, 6M HCl, and
0.6M H3BO3 through a testing period of 456 days. The test
conditions are considered “aggressive” as the tear-offs were
directly exposed to the various acid vapors. The observation of
a circular yellow stain on the Lexan blank under HNO3 acid
exposure at 0” after 17 days, clearly indicates that the ProTec
tear-offs may be more chemically resistant than the Lexan sheet
under those service conditions. The complete removal of the
tear-offs after long-term exposure suggests that the mechanical
integrity of the ProTec system was not degraded and visual
clarity could be restored as needed.
To assess the resistance of the tear-offs to highly basic
materials, a simulated DWPF sludge with a starting pH of 12.9
was “splattered” onto a tear-off system. The sludge was partially
removed through the use of deionized water and a wipe leaving
a smear of sludge across both the tear-off and Lexan blank.
Upon removal of the outer tear-off, visual clarity was restored to
the tear-off portion leaving the sludge residue on the Lexan
blank. Upon visual inspection of the tear-off, no visual sign of
reaction or degradation could be detected. The results indicate
that the ProTec tear-off is impervious to the high pH sample.
The “scratch resistance” testing demonstrated that marks
or scratches can be induced by the manipulators (in “mock-up”)
on both the blank and tear-off systems. The scratch marks were
consistent with those observed in actual service in the SRNL
Shielded Cells. Upon removing the outer tear-off layer with the
manipulators, visual clarity was restored. The result of this test
not only confirms the conceptual “erasing” of marks or scratches,
but also was the initial demonstration of the ability of the
manipulators to effectively and efficiently grasp and remove the
outer layer tear-off.
The results of the in-situ SRNL Cell #15 and DWPF
Sampling Cell tests suggest that the use of the tear-off system
is viable under realistic service conditions. In the tests in SRNL
Cell #15, the tear-offs showed no signs of visual degradation up
to ~700 days exposure (with a cumulative gamma dose
estimated to be ~336,000 rad). In addition, the outer layer
tear-off was successfully and completely removed suggesting
no mechanical degradation after the gamma radiation
exposure. The tear-offs also withstood the extremely harsh
conditions within the DWPF Analytical Sampling Cells (extremely
high radiation fields, acidic vapors, airborne particulates, etc).
After ~6 months of actual field service under these conditions,
the outer layer tear-off was completely removed restoring
visual clarity of the test coupons.
License and Patent Application Premier
Technology, Inc. Lyle Freeman
In 2006 and 2007 presentations regarding the Mylar
laminated ProTec tear-off window protection sheets for Hot Cell
and Glovebox windows at the American Glovebox Society (AGS)
annual conferences, Dr. David Peeler introduced the Mylar
ProTec layer film glass protection product. This product is an
obvious value added feature to our already existing product line
of Hot Cells, Gloveboxes, and Leaded glass windows. When we
were approached about a product technology transfer from
Savannah River National Laboratory (SRNL) we were very
interested in further discussion. Because of our serious interest
in this licensing opportunity, personnel from SRNL involved in
the technology transfer and the licensing process visited our
facility in Blackfoot, Idaho to negotiate the transfer of the ProTec
tear-off product. We were able to agree on the terms of the
licensing agreement and finalize the technology transfer.
After the transfer was completed, we continued to be very
involved in the R&D process. The testing of the material, was
performed by SRNL in the laboratory and in several research
Hot Cells. The Mylar tear-off sheets that were used for testing
were intended to protect face shield visors on safety helmets
and allow the user to tear off a layer if the shield became dirty
and the user’s visibility was impaired. The tear-off concept for
the face shield visor is the same concept used on viewing
windows for containment devices; however the size and pattern
used for the helmet visor would not satisfy the need and
requirement for Hot Cell and Glovebox windows.
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REGISTRATION FORM

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In an effort to standardize the size of the multi layered Mylar
film we came to the conclusion that it was impossible to confirm
any precut sizes due to the fact that there is no standard window
size in a Hot Cell or Glovebox. The design of the containment
device, determines the window size based on the function and
process requirements, what needs to be seen, view angles and
process that require specific access or viewing conditions.
Based on that conclusion, we determined that as the Mylar
ProTec tear-off seller we needed our material supplier to
provide the Mylar laminated layered sheets in sizes that we
could custom cut to meet the size requirement of each containment
viewing condition. We concluded that we could live with
three sizes of sheets, small, medium and large that could be
custom cut to fit all window size applications with minimal drop
and waste. It was determined that four laminated layers were best
to allow visual clarity without distortion. Our supplier also
researched the laminate adhesive to insure no tacky residue
would be left on the remaining sheets when the dirty layer was
removed and also when the last layer was removed from the
glass. One of the requirements of the licensing agreement is that
the names or logos or a method of identification for Premier
Technology, Inc. and SRNL be visible on each individual sheet
that is sold and installed. After some research, we came up with
a tab that would identify the two companies. A sequential
number or letter is also used to identify the number of layers
that are left and the next layer to be removed. The tabs are
provided separately from the Mylar sheets so that they can be
printed with the required information. Also, because of the large
number of windows sizes that could potentially be fit with the
Mylar Pro Tec tear-off sheets and the need to custom cut nearly
every sheet to fit any given window size, we could not work out
a method of incorporating the tab into the base material. The
tabs are designed to be applied when the sheets are being
custom cut. This also allowed us to locate the tabs on the sheets
for best access with a glove in a Glovebox or with a Manipulator
or robotic arm in a Hot Cell. The adhesive on the tabs was
another issue to resolve. We needed to make sure that the tab
would stick to the Mylar sheet under a reasonable amount of pull.
Our supplier came through with adhesive and tabs that met our
requirements. On the edge of the Mylar laminated sheet where
the tabs are to be applied we were able to work out with the
manufacture a method of leaving about 1/2” on one edge that
has no adhesive, so that we can apply the tabs without pulling
the laminate apart to put the tabs in place.
Windows in a containment device whether it be a Hot Cell
or Glovebox are very costly to replace. There are down time
issues, radiation contamination issues and the cost of the glass,
especially in Hot Cells that are equipped with very costly leaded
glass. The cost to refurbish or replace the glass is especially
high when you are required to build a temporary enclosure or
tents around the Hot Cell or Glovebox to contain the spread of
contamination when you break containment while extracting the
window, or refurbishing or replacing and re-installing a window.
The ProTec tear-off sheets will allow users to go much longer
without costly refurbishment or replacement of windows, and in
most cases the Mylar laminate sheets can be replaced with a
new four layer laminate sheet when the last sheet of the four
sheets is removed from the window.
During the time that R&D processes and negotiations with
material suppliers were conducted some market research to try
to determine the interest in the tear off product was also done.
Mylar Protective Coatings for Glovebox, Shielded Cells,
and Chemical Hood Windows
In the limited amount of inquiries that were made we believe
that there is a potential market for this product. The ProTec
tear-off product is very resistant to numerous caustic acids and
abrasive materials. Some processes that require working with
acids and other caustic materials on stainless steel surfaces can
benefit by applying the Mylar tear off sheets to the surface
temporally to give protection to the base material.
While we will continue our effort to identify additional uses
for the Mylar tear off product, its use in the Glovebox and Hot
Cell market alone makes it a valuable addition to our already
existing product line of Hot Cells, Gloveboxes, and Leaded glass
windows.
Premier Technology, Inc. (Blackfoot, Idaho) has obtained
exclusive licensing rights for the ProTec tear-off system from
the Washington Savannah River Company (WSRC). The ProTec
tear-offs are patent pending under U.S Patent Application
#11/546,640 and PCT/US2007/014286. �
References
Bibler, NE. 2005. Dose Rate Determination in Support of Saltstone
Flammable Gas Generation Tests in SRNL Shielded Cells, SRNL-ITS-2005-
00153.
Cook, JE. 2006. ProTec Tear-off Evaluations in DWPF Sampling Cell,
CBU-WLS-2006-00010, June 9, 2006.
George, JC, DK Peeler, JW DuVall, and RW Blessing. 2005. ProTec‘ Tear-
Offs: A Preliminary Assessment, WSRC-TR-2005-00386, Westinghouse
Savannah River Company, Aiken, South Carolina.
Peeler, DK. 2008. ProTec Tear-Offs: Results of Long Term Testing, WSRC-
STI-2008-00326, Westinghouse Savannah River Company, Aiken, South
Carolina.
AGS Sustaining Members
ABW Technologies, Inc.
6720 191st Pl NE
Arlington, WA 98223-4666
Bus: (360) 618-4400
Fax: (360) 618-4444
adura@abwtec.com
Babcock & Wilcox
Clinch River, LLC
400 Centrifuge Way
Oak Ridge, TN 37830
Bus: (865) 481-7156
Fax: (865) 241-7135
cdirwin@babcock.com
Byers Precision Fabricators, Inc.
675 Dana Road
Hendersonville, NC 28792
Bus: (828) 693-4088
Fax: (828) 692-5753
rogerbyers@byersprecision.com
Emcel Filters
Blatchford Road
Horsham, West Sussex RH13 5RA
jallen@emcelfilters.co.uk
M. Braun Inc.
14 Marin Way
Stratham, NH 03885-2578
Bus: (603) 773-9333
Fax: (603) 773-0008
m.boutin@mbraunusa.com
Miwa Mfg. Co. LTD.
9-8, 5 - Chome, Torikaihonmachi
Settu-city
Osaka, Japan, 566-0052
wada@miwass.co.jp
Miyachi Unitek Corp.
1820 S. Myrtle Avenue
Monrovia, CA 91730
Bus: (626) 303-5676
Fax: (626) 599-7906
ivonet.gomez@muc.miyachi.com
Robatel Technologies, LLC
PO Box 12007
Roanoke, VA 24022
Bus: (540) 989-2878
tgrochowski@robateltech.com
To become a sustaining member, contact the AGS Central Office
(800)530-1022 or
ags@gloveboxsociety.org
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