ML092720439
| ML092720439 | |
| Person / Time | |
|---|---|
| Site: | 07000925 |
| Issue date: | 11/02/1989 |
| From: | Rogers W Cimarron Corp |
| To: | Region 3 Administrator |
| Shared Package | |
| ML092720355 | List:
|
| References | |
| Download: ML092720439 (16) | |
Text
PU PLANT SOLVENT EXTRACTION-SX contained one U shaped 34 foot high glovebox.
This glovebox was anchored to the wall and contamination was spread to the wall and floor during removal of this glovebox.
After glovebox removal, the walls and floor were coated with a stripable paint to tie up loose contamination.
After removal of the stripable paint and floor coating, direct readings averaged approximately 600 dpm/100 cm2 2
with a high of 8000 dpm/100 cm.
We proceeded to grit blast the walls and floor and reduced all alpha readings to less than 100 2
dpm/l00 cm Our low energy gamma survey indicated a problem along the' south wall floor seam.
We removed a small portion of the south floor and a small amount of sand to correct this problem.
We used a Ludlum 2220 with a Ludlum 43-27 (large area detector for scan) and a 43-68 for release survey.
All smears were taken on Whatman smear paper and counted in a Hewlett Packard 5560A (low background) automatic sample counter.-
W.A.
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Pu PLANT RELEASE SURVEY PLAN
- 1. For initial decontamination all surfaces will be scanned with an Eberline PRM-6 with a Radeco alpha scintillation probe.
Back-ground will be maintained at less than 100 CPM(200 dpm).
All areas greater than twice background will be marked and reading will be taken with a release survey instrument to document cont-amination levels and random large area smears will be taken.
- 2. After these initial areas are decontaminated, all floor surfaces and the base of each wall will be completely surveyed with a digital readout release instrument and a Ludlum large area gas proportional alpha detector and random smear samples will be taken.
Release instrumentation shall have a minimum detectable level of at least 50 dpm/100 cm2.
- 3. All hot spots greater than or equal to 100 dpm/100 cm2 ident-ified will be decontaminated.
- 4. A random survey with a release instrument will be taken on the walls and ceiling to try to identify any other problem areas.
- 5.
If no problems are identified, each room will be gridded off into approximately 2 meter on a side square on the walls and floor and five readings will be taken in each grid.
Readings shall be taken in the center and at the midpoint from the center to each corner.
- 6.
Each ceiling has closely spaced rafters that will not be easily divided into 2 meter squares.
Because of this, we will take readings on the bottom of each rafter at 2 meter inter-vals and one reading centered on the ceiling between rafters.
Readings on each rafter will be staggered one meter.
- 7.
These release readings will be documented on a map that is drawn to approximately scale measurements in meters.
- 8. Data provided on each map:
- 1. Survey block numbers, identifiable on a scale drawings.
- a. room or area name or number.
- b. surface surveyed.
- c. type of measurement and units.
- 2.
Name of surveyor taking measurements, date of survey, and location.
- 3.
Type, model number, calibration data, sensitivity limit, background, and source response of instruments used in survey.
- 4.
When a block surveyed is below the sensitivity of the instru-ment, the fact that such a measurement was made should be included as significant data.
- 9. All release survey smears will be taken on Whatman smear paper and counted in the automatic sample counters.
Each smear will cover approximately 100 cm2.
- 10. There will be at least 30 survey blocks in each area to be released.
- 11. Piping and ductwork will be surveyed on all accessable sides at 2 meter intervals.
If more than one line is running parallel in a pipe rack, readings shall be staggered at one meter intervals.
- 12. All readings taken that only cover part of a probe area will be corrected to dpm/100 cm2.
- 13.
No survey block will measure less than one meter on a side.
- 14.
No survey block will measure more than 3 meters on a side.
- 15. All portable release survey instruments will be calibrated quarterly and all instruments in use will be source checked daily.
Table I-1.
Acceptable surface contamination levels Nuclidesa Averageb'e'T Maximumb,,J Removableb,e,*
U-nat, U-235, U-238, and 5,000 dpm a/l00 cm7 IS,000 dpm a/100 cm 2 1,000 dpm ct/l00 cm 2 associated decay products Transuranics, Ra-226, Ra-228, 100 dpm/100 cm 2 300 dpm/100 cm 2 20 dpm/100 cm 2 Th-230, Th-228, Pa-231, Ac-227, 1-125, 1-129 Il-nat, Th-232, Sr-90 1,000 dpm/lO0 cm2 3,000 dpm/100 cm2 200 dpm/100 cm2 Ra-223, Ra-224, U-232, 1-126, 1-131, 1-133 Beta-gamma emitters (nuclides 5,000 dpm By/100 cm 2 15,000 dpm By/l00 cm 2 1,000 dpm By/100 cm2 with decay modes other than alpha emission or spontaneous fission) except Sr-90 and other noted above.
a here surface contamination by both alpha-and beta-gamma-emitting nuclides exists, the limits established for alpha-and beta-gamma-emitting nuclides should apply independently.
hAs used in this table, dpm (disintegrations per minute) means the rate of emission bv rqdin.ioctive material as determined by correcting the counts per minute observed by an appropriate detector for background, efficiency, and geometric factors associated with the instrumentation.
eMeasurements of average contaminant should not be averaged over more than I square meter.
For objects of less surface area, the average should be derived for each such object.
d'he maximum contamination level applies to an area of not more than 100 cm2.
eThe amount of removable radioactive material per 100 cm 2 of surface area should he determined by wiping that area with dry filter or soft absorbent paper, applying moderate pressure, and assessing the amount of radioactive material on the wipe with an appropriate instrument of known efficiency.
When removable contamination on objects of less surface area is determined, the pertinent levels should be reduced proportionally and the entire surface should be wiped.
fThe average and maximum radiation levels associated with surface contamination resulting from beta-gamma emitters should not exceed 0.2 mrad/hr at 1 cm and 1.0 mrad/hr at 1 cm, respectively, measured through not more than 7 milligrams per square centimeter of total absorber.
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