ML092720455
| ML092720455 | |
| Person / Time | |
|---|---|
| Site: | 07000925 |
| Issue date: | 11/02/1989 |
| From: | Rogers W Cimarron Corp |
| To: | Region 3 Administrator |
| Shared Package | |
| ML092720355 | List:
|
| References | |
| Download: ML092720455 (39) | |
Text
Pu-Plant Room 121 While in production room 121 was used for fuel rod cleaning, final inspection, and storage.
During decomissioning we used this room for waste storage.
On our initial scan, we identified five locations on the floor bewteen 100-300 dpm and none on the walls.
After cleaning these spots, our final release survey was preformed.
We used a Ludlum 2,220 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.*.,_.-ý'-.
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 1-I.
Acceptable surface contamination levels NucI idesl Ave rageo.f Max imum 0' R~emovablec~e U-nat, U-235, U-238.
and associated decay products Transuranics, Ra-226, Ra-228, Th-230. Th-228, Pa-231, Ac-227, 1-125, 1-129 Ti-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 dpm u/IO0 cm2 100 dpm/I00 cm2 1.000 dpm/l00 cm2 S,000 dpm By/n00 cm2 IS,ll(l dpm f,/ 1(I) cm2 33)0 dpm/llo cm.
3,000 dpm/IOU cm 2 15,000 dpm 01/lO0 cm7 1,000 dpm a/lO0 cm?
20 dpm/IUU cm2 200 dpm/I00 cm' 1,000 dpm By/100 cmK aWhere surface contamination by both alpha-and heta-gamma-emitting nuclides exists, the limits estahlkshed for alpha-1 and beta-gamma-emitting nuclides should apply independently.
bAs used in this table, dpm (disintegrations per minutel means the rate of emission by raill-artive material as determined by correcting the counts per minute observed by an appropriate detector for hackgro..d, efficiency, and geometric factors associated with the instrumentation.
eMeasurements of average contaminant should not he averaged over more than I square meter.
lor objects of less surface area, the average should be derived for each such object.
dithe maximum contamination level applies to an area of not more than 100 cm2.
ThIle amount of removable radioactive material per 100 cm of surface area should be 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 he wiped.
mThe average and maximum radiation levels associated with surface contamination resulting from heta-gamma emitters should not exceed 0.2 mrad/hr at I cm and 1.0 mrad/hr at 1 cm, respectively, measured through not more than 7 milligrams per square centimeter of total absorber.