ML092720436
| ML092720436 | |
| Person / Time | |
|---|---|
| Site: | 07000925 |
| Issue date: | 11/02/1989 |
| From: | Rogers W Cimarron Corp |
| To: | Region 3 Administrator |
| Shared Package | |
| ML092720355 | List:
|
| References | |
| Download: ML092720436 (98) | |
Text
0 Pu-Plant Room Exhaust System The Pu-plant was maintained at a negative pressure at all times during production and cfean up with this system.
Each floor exhaust hole had an absolute filter installed just below the floor level, and clean fiberglass prefilters were maintained on top of these abso-lute filters.
These exhaust holes were connected to the exhaust tunnel by transite exhaust duct, that was installed before the con-crete floors were instal-led.
Control louvers were installed on each duct just inside the tunnel, to maintain a proper air flow pattern through out the building.
This exhaust tunnel is connected to the exhaust fanroom by a 6'x12'x26' riser.
We had to decontaminate most filter housings from the filter seal up to the floor level. We found contamination in the filter housings below the filter seal in:
- 1. Room 129 -
Maximum 1,000 dpm/100 cm2 direct, 500 dpm/100 cm2 smear.
- 2.
Room 132 South filter 300 to 500 dpm/100 cm 2 direct, 300 dpm/100 cm2 smear.
Note:
These two filter housings (129 and 132) had a liquid stain where these levels were found.
- 3.
Room 133 -
100 to 1500 dpm/100 cm2 direct 20 to 100 dpm/100 cm 2 smear.
- 4.
Room 134 -
300 to 500 dmp/100 cm2 direct 20 to 100 dpm/100 cm2 smear.
- 5.
Room 138 -
100 to 200 dpm/100 cm2 direct 20 toQ100 dpm/100 cm 2 smear.
- 6.
Room 141 -
100 to 300 dpm/100 cm2 direct 20 to 100 dpm/100 cm2 smear.
- 7.
Room 123 300 to 500 dpm/100 cm2 direct 20 to 100 dpm/100 cm 2 smear.
Note:
These filter housings (133,
- 134, 138, and 123) may have been contaminated while removing filter.
- 8.
Room 116 300 to 500 dpm/100 cm2 direct 300 dpm/100 cm2 smear. This entire filter housing was extremely oily.
- 9.
Room 124 1,000 to 12,000 dpm/100 cm2 direct -
2,000 to 5,000 dpm/100 cm2 smear.
We removed the steel filter sleeves in this room.
- 10. Room 127, 1,000 to 2,000 dpm/100 cm2 direct 128,BO-l 500 dpm/100 cm2 smear.
We removed the steel filter housings and all steel duct in these four rooms.
We found contamination in the following transite ducts:
- 1. Room 124 west duct -
North end 500 dpm/100 cm2 direct.
- 2.
Room 124 east duct -
This duct had a moisture stain along the bottom of the duct for its entire run.
This stained area 10,000 to 30,000 dpm/100 cm2 direct and up to 2,000 dpm/100 cm2 smearable.
Non stained area 50 to 5,000 dpm/100 cm2 direct and up to 1,000 dpm/100 cm2 smear.
- 3.
Room BOI duct -
Spot levels of 1,000 to 5,000 dpm/100 cm2 direct and up to 1,000 dpm/100 cm2 smear.
We spent approximately 8 weeks of extensive decontamination to reduce these levels to release limits.
We removed steel sleeves in-side these ducts and then sanded the entire length of these ducts.
Where the duct was cracked in the bottom we removed a portion of the bottom of these ducts to check the soil below.
We removed a small amount of soil from three locations.
The initial survey in the exhaust tunnel and riser were:
2
- 1. Walls and ceiling -
300 to 400 dpm/100 cm direct 2
100 dpm/100 cm smear.
- 2.
Control louvers 500 to 2,000 dpm/100 cm2 direct 500 2
dpm/100 cm smear.
2
- 3.
Floor -
1,000 to 12,000 dpm/100 cm, direct 500 2
dpm/1000 cm smear.
2
- 4. Piping and conduit -2,000 to 4,00 dpm/l00 cm direct.
500 dpm/100 cm smear.
We vacuumed the entire tunnel and removed the control louvers.
We shot blasted the entire tunnel and deconed the piping and conduit.
Our low energy gamma survey indicated a problem in a crack under room 124 east duct run, and a crack that ran to the tunnel drain pipe.
We chiseled out these cracks and removed the drain pipe.
We deconed and released the exhaust fans that were associated with this system.
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.
0 0
Table I-1.
AccepLable surface contamination levels Nuclides'i Average "1,0.faximu il-nat, Ul-23S.
UI-238, and 5,000 dpm Mu/Id Cm 15,111)11 dtli *,
OI cmi associated decay products Transuranics, Ra-226, Ra-228, 100 dpm/I00 cm 301"1 dlpm/lii)
C'Ml 1h-230, Th-228, Pa-231, Ac-227, 1-12S, 1-129 Th-nat, Th-232, Sr-90 1,000 dpm/ 1(1 cm2 3,nO) dpm/100 cmn Ra-223, Ra-224, U-232, 1-126.
1-131, 1-133 Beta-gamma emitters (nuclides 5,0(01 dpm Bry/IO cm 2 15,000 dplm V,1/lOl0 cml with decay modes other than alpha emission or spontaneous fission) except Sr-90 and other noted above.
Rtemovable oj I,000 d1'm w*n/o0 cm' 20 dpm/10 cm' 200 dpm/I00 cm, I,10)0 dpm By/100 cm' I-J (TI aWhere surface contamination by both alpha-and heta-, wmma-cmi tt1ug nuclides exists, the limits establimshed for allhafl anid beta-ganna-emitting nuclides should apply i;,depeidently.
hbAs used in this table, dpm (disinteprations per minute) means the rate of emisqion hy rdhliloctive material as determined by correcting the counts per mlilute observed by an alpplrolpriate detector fur hacklgrommld efficiency, and geometric factors associated with the Instrumentation.
C Measurements of average contaminallt should not he avuIal.ed over mlore than I squaJ re meter.
l()r oblmjects of less surface area, the average should be derived for each such object.
dilhe maximum contamination level applies to an area of not more than IUl cmC.
0 Ile amount of removable radioactive material per 100O cm 2 of surface area should he determined hlv wipin g 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 contamliation on objects of less surface area is determined, the' pertinent levels should be reduced prolportionally and the entire surface should he wiped.
WTe average and maximum radiation levels associated with surface contamination resultinR from heta-R~mma emitters should not exceed 0.2 mrad/hr at I cm and L.0 mrad/hr at I
- cimi, respectively, mellaSulred tlhoughl:
not more than 7 milligrams per square centimeter of total absorber.