ML092720473
| ML092720473 | |
| Person / Time | |
|---|---|
| Site: | 07000925 |
| Issue date: | 11/02/1989 |
| From: | Rogers W Cimarron Corp |
| To: | Region 3 Administrator |
| Shared Package | |
| ML092720355 | List:
|
| References | |
| Download: ML092720473 (18) | |
Text
Pu-Plant Room 124 During production this room contained our pellet presses, cal-ciner, Harper furnace, pellet grinder, inspection gloveboxes, and outgas furnace.
After this equipment was removed, we started re-moval of the glovebox exhaust system.
While removing this glovebox exhaust system, we had a section of this pvc pipe, that was just upstream of the pellet grinder box, fall to the floor.
We increased room 124 negative and sealed all anchor holes,cracks,and floor seams immediately after this accident. This accident contaminated the en-tire room and we spent approximately three months steaming the walls, floor, and ceiling to remove smearable contamination. Levels of fixed contamination were from,500 dpm/100 cm2 to 2000 dpm/100 cm2 aver-2 age on ceiling and walls, with a maximum of 100,000 dpm/100cm on the east wall by the double doors that went to production hall.
We removed these doors and framework and some blocks that had high levels of contamination.ý We then blasted wall and ceiling, removed the floor coating and then blasted the floor.
We preformed a scan survey and spot blasted the wall and blasted the entire floor again Before starting our final release survey we took smears in all anchor holes in walls and floor and did a low energy gamma survey. Because of the results of these surveys one floor seam was removed and half of some wall blocks were removed.
We also used a core drill to remove the anchors in the floor and then surveyed these holes in the floor.
We used a Ludlum 2220 with a Ludlum 43-17 low energy gamma probe to survey all cracks and seams.
A Ludlum 2220 with a Ludlum 43-68, 43-4, or 43-27 was used with P-10 gas for all alpha release surveys.
All smears were taken on Whatman smear paper and counted in a Hewlett
-Packard 5560A (low background) automatic sample counter.
W. A.
Rogers
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.
9 Table I-1.
Acceptable surface contanlinatiorn levels NucI ides'I AveragebJ Max inmumI.
IJ Removableb' t J' U-nat, tl-23S, U1-238, and associated decay products Transuranics, Ra-226, Ra-228, 1h-230, Th-228, Pa-231, Ac-227, 1-125.
1-129 Th-nat, Th-232, Sr-90 Ra-223, Ra-224, U-232, 1-126.
1-131, 1-133 Beta-gamma emitters (nuclides with decay modes other than alpha emission or spontaneous fission) except Sr-90 and other noted above.
5,000 dpln (u/lll0 cm' 100 dpm/l00 cmn?
1,000 dpm/l0}
cm2 5,000 dpm IOy/l00 cm 2 IS,=)
dpm ",/
100 cm' 301) dpm/Il1)
CM2 3,000 dpm/I01 cm, 15.000 dpm H(t/l00 cm2 I.(1m0 dpm a/I100 cm2 20 dpim/l00 cm2 200 dpm/l00 cm?
1,000 dpm BYll00 cm' Where surface contamination by both alpha-and heta-Ramma-emittiig nuclides exists, the limits estahllshed for alpha-'
and beta-gamma-emitting nuclides should apply independently.
bAs used in this table, dpm (disintegrations per minutel means the rate of emission by rnadioactive material as determined by correcting the counts per minute observed by an appropriate detector for hackgrouln, efficiency, and geometric factors associated with the instrumentation.
CMeasurements of average contaminant should not he averaged over more thla I square meter I or.objects of less surface area, the average should be derived for each such object.
dThe maximum contamination level applies to an area of not more than 100 cm'.
The amount of removable radioactive material per 100 cm2 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 resultingl from hera-gamma emitters should not exceed 0.2 mrad/hr at I cm and 1.0 mrad/hr at I cm, respectively, measured through not more than 7 milligrams per square centimeter of total absorber.
'I-0-i