ML20009C292
| ML20009C292 | |
| Person / Time | |
|---|---|
| Issue date: | 06/30/1981 |
| From: | Book H, Riedlinger B, Skov D, Thomas R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| To: | |
| Shared Package | |
| ML20009C291 | List: |
| References | |
| NUDOCS 8107200439 | |
| Download: ML20009C292 (11) | |
Text
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i!UCLEftR REGULATORY COMMISSI0t!
F~ :E GF !!!SPECTIO.'l AllD E!!FORCEI'ENT REGIO;-l V Report o.81-02 License 74 4-01043-10 Priority IV Category E (1-A)
Licensee: SRI International 333 Ravenswood Avenue Menlo Park. California 94025 Facility ::ame: Hot Cell Facility Insoection at:Buildina 131. Camp Parks Military Reservation Ins:ection ConoucteaMune 9.1981 Inspectcrs: 3 0. $p89,w]
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B. A. Riedlinger(,lRadiation Specialist Date Signea 9,L w 4holm D. D. S v, Radiation Specialist Date Signed Approvedby:b.h.
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R. D. Thomas, Chief, Margrials Radiation C' ate Signed Prot tion Sec 'on 4
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Approved by:
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H. E. Book, Chief, Radiological Safety Branch Date Signed Summary:
Inspection on June 9,1981, Report No. 81-02 This report contains the results of a second confirmatory survey made at the Camp Parks Hot Cell Facility following notification by the licensee that the building had been decontaminated to acceptable levels for release to unrestricted use. A total of 9 inspector hours were expended by two inspectors who performed the survey on June 9, 1981.
Results:
The confirmatory survey, consisting of direct field measurements and wipa analysis, detennined that contamination was present in several locations of the Hot Cell Area within Building 131 which exceeded NRC guidelines for release to unrestricted use. The NRC survey was therefore terminated until the licensee performs the required decontamination, performs a final survey, and submits the survey results for evaluation by the NR",.
RV From 219 (1) 8107200439 810701 l
NMS LIC30 04-01043-10 PDR
DETAILS 1.
Person _ Contacted James L. Thomas, Radiation Safety Officer, SRI International
===2.
Background===
On April 21 and 22,1981, two inspectors from NRC:RV conducted a confirmatory survey for final clecrance of the Camp Parks Hot tell Facility (Building 131). The results of that inspection as contained in report 81-01 which was sent to the licensee, indicated that additional decontamination was required in some areas of Suilding 131.
The NRC Region V office received a report on May 14, 1981 and a foli a-up letter on June 3,1981 from Mr. James Thomas, SRI International, which gave the results of a further decon+ amination and radiation survey which was performed by the licensee as requested by NRC:RV.
Based on the results of the licensee survey, a second confirmatory survey was carried out by two NRC:RV inspectors on June 9,1981 with the objective of final clearance of Building 131.
The survey criteria were based on the requirements established by " Guidelines for Decontamination of Facilities and Equipment Prior to Release for Unrestricted Use or Terminution of Licenses for Byproduct, Source or Special Nuclear Material", November,1976.
3.
Reference Sources An NRC Region V strontium-90 counting source (Serial No. 7722) was selected for use in the calibration of portable survey instruments and laboratory proportional counter. The Sr-90 calibration source yielded 2520 disintegrations per minute of activity on August 25, 1977.
Based on a half-life of 28 years, the source was calculated to have a decay-corrected activity of 2300 disintegrations per minute in June, 1981.
4.
Field Radiation Detection Instruments Beta-gamma surface contamination levels were measured with two por table suryny instruments:
a.
Eberline Model E-520 with pancake GM detector Modal PP-260 (NRC 8251) b.
Eberline Model E-520 with pancake GM detector Model HP-260 (NRC 8253)
Both instrumenu ere calibrated with a Sr-90 counting source described above (#7722) which yielded an average of 500 gross counts per minute
(NRC 8251) and 550 gross counts per minute (NRC 8253) on the X0.1 scale.
The measurement was made with the source in surface contact with the 2
detector window (thickness 1.4-2.0 mg/cm ) and the instrument response adjusted to the slowest setting available (maximum counter-clockwise position) to minimize instrument meter needle fluctuation. The background radiation measured an average of 75 counts per minute (NRC 8251) and 150 counts per minute (NRC 8253).
Under these conditions, the instruments gave 19.6 and 21.7 percent efficiencies. The average efficiency was, therefore, 20 percent.
5.
Acceptable Contamination Release Levels As with the previous confirmatory survey conducted on April 21 and 22, 1981, it was assumed for the purpose of the present survey that all contamination detected was due to strontium-90. This assumption was based on the large quantity of strontium-90 used under the license as well as other factors which are discussed in the previous NRC:RV confinnatory survey report (May 13, 1981) No. 81-01.
The acceptable surface contamination levels which are applicable for the present survey and which are taken from the guidelines document for decontamination and release of facilities to unrestricted use are summarized in Table I:
TABLE I AfCEPTABLE SURFACE CONTAMINATION LEVELS MAXIMUM AVERAGE REMOVABLE Radiation 1.0 mrad /hr at 0.2 mrad /hr at N/A 1 cm at I cm Contamination 3,000 dpm/100 1,000 dpm/100 200 dpm/100 square square square centimeters centimeters centimeters 6.
Meter Allowable Readings Meter allowable readings (MAR), exclusive of natural background radiation, were calculated based on the response of the field instrument to the strontium-90 reference source and on the release levels for surface 4
contamination. Mgximum and average MAR values were developed for spot (less than 100 cm ) and wide areas (greater than or equal to 100 cm )
of contamination as defined using the methodology described in the first confirmatory survey report 81-01. The details of the MAR calculations are described in Attachment 1 and the MAR valet are tabulated below (Table II).
, TABLE II FIELD INSTRUMENT CONTAMINATION L1ilTS*
ADEA 0F CONTAMINATION MAXIMUM MAR AVERAGE MAR 2
Spot (<100 cm )
600 cpm 200 cpm 2
Wide (>100 cm )
90 cpm 30 cpm
- Readings with subtraction of natural background radiation.
7.
Wipes Survey Removable contamination was evaluated bj wiping the surface using Whatman
- 42 filter paper by moderate pressure over an area of 100 square centimeters.
The wipes were counted in a Region V NMC PC-55 gas flow proportional counter (NRC Serial No. 383). With a background of 67 cpm and use of the Sr-90 reference source (Serial No. 7722, 2520 dpm on 8-25-77),
the efficiency of the proportional counter was determined as 67 percent on June 10, 1981.
8.
Inspection Details a.
Building Intericr Survey The NRC Region V confirmatory survey which vas performed April 21 and 22, 1981 determined that several areas of the Building 131 Hot Cell Facility remained contaminated to a level of activity above the release levels according to NRC gtidelines. These areas as described in NRC:RV Report 81-01, included the former Hot Cell Area at the south end of the buildi.'g, the porch arez south of the b@ cell, crawl space under the jacch, the roof over the pSrch, and 1.he restroom at the north end of the bui P*ng.
The previous survey also determined that some other areas of Building 131 met the requirements of the NRC guidelines with rMpect to fixed and removable contamination and therefore fulfilled the criteria for release to unrestricted use.
See Report 81-01.
In the current survey, attention was therefore directed to those arec; of Building 131, particularly the Hot Cell location, which were identified as contaminated by the previous NRC survey and which was reported to be decontaminated according to the survey reports of May 6 and June 1,1981 received by NRC:RV from SRI In ternational.
. The results of the survey measurements pertormed with the field instruments on June 9,1981 and of the wipes taken on the same day and analyzed on June 10, 1981 are tabulated in Attachment II. The locations of the direct survey and wipes are thown in Figures I and II.
(1) West Wall of Hot Cell Area The entire wall from the floor to the ceiling and from the south wall to the door on the west wall was thoroughly surveyed with the GM pancake probes.
Several locations were noted to be in excess of the release limits specified in Tables I and II.
(2)
East Wall of Hot Cell Area A thorouah survey was perforned over nearly the entire East Wall of the Hot Cell Area using pancake GM detectors. The maximum direct reading was 15,000 cpm. This and a number of other locations on the wall were noted to exceed the release levels for contamination by reference to Tables I and II.
A spot survey for removable contamination was made consisting of one wipe which indicated detectable activity, but which was beled t:1e release limits.
(3) South Wall of Hot Cell Area A spot survey for fixed and remcyable contamination was made over the South Wall of the Hot Cell Area.
One location was detected which did not meet the NRC guidelines for fixed centamination.
b.
Building Exterior Survey A spot survey was completed in the crawl space under tile west location of the porch area adjacent to the Hot Cell Area.
A direct survey indicated a maximum reading of 150 cpm (with background subtracted) over an approximately one square foot area on the ground which is marginalli in excess of the NRC guidelines.
c.
Conclusion A survey of the fonner Hot Cell Area indicated that several locations on the East, West and South Walls were contaminated with radioactive material in excess of the release limits as established by NRC guidelines. These results are contrary to the licensee reports l
of April 6, May 6, and June 1,1981 which indicated complete decontamination of the Hot Cell Facility to activity levels which are considered acceptable for release to an unrestricted area.
. On the basis of the above result, it is concluded that:
1.
The decontamination and resurvey efforts on the part of the licensee have not been carried out with sufficient care and thoroughness to ensure that the release limits are not exceeded and which would permit return of Building 17' to unrestricted use.
2.
More adequate surveys need to be perforned by the licensee to identify and evaluate the extent of all locations of existing copramin?. tion in order to assess the need for additional decontaminav.n relative to NRC guidelines.
d.
Exit Meeting The licensee representative was informed during the exit meeting on June 9, 1981, that the Hot Cell Area was still contaminated to unacceptable levels and thct additional effort would be required by the licensee to effect decontamination. A final survey and written report should be completed by the licensee and submitted to NRC Region V for evaluation. The licensee representative did not state when the decontamination effort would continue or when a report would be forthcoming.
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Vf ATTACINENT 1 I.
Meter Allowable Readings (MAR) Contamination Calculations In order to equate the acceptable contamination limits established in Table I of this report, to the MAR values for fixed ccntamination, it was necessary to establish calculated values for spot and wide surface area contamination levels.
For the purpose of calculating instrument response for spot contaminagion areas, it was assumed that all radioactivity is contained within a 15 cm surface area, which is the sensitive area of the pancake GM detector.
For-the wide surface area contamination, it I
was assumed that t radioactive material has distributed over an area in excess of 15 cm The pancake GM detector had an established efficiency of 20%.
To be equivalent to the acceptable limits specified in Tgble 1, the MAR values have been calculated and extrapolated to a 100 cm area, a.
Spot Contamination:
MAR (maximum)
(3,000 dpm) (.20) = 600 cpm Therefore, a MAR of 600 cpm is equivalent to 3,000 dpm per 100 square centimeters.
1 MAR (average) = (1,000 dem) (.20) = 200 cpm Therefore, a MAR of 200 cpm is equivalent to 1,000 dpm per 100 square centimeters.
('
b.
Wide Area Contamination:
2 MAR (maximum) = 600 cpm (
m) 2 0
90 cpm
=
Therefore, a MAR of 90 cpm is equivaient to 3,000 dpm per 100 square centimeters.
2 m)
MAR (average) = 200 cpm (
2 0
30 cpm i
=
Therefore, a MAR of 30 cpm is equivalent to 1,000 dpm per 100 sauare centimeters.
l l
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ATTACHMENT II DIRECT READING AND WIPE TEST CONTAMINATION SURVEY 1.
Direct Survey with Eberline G-M Pancake Probe on June 9,1981.
Location Noted Meter Reading on Figures I & II Description of Location with Background Subtract A
On East Wall, 2' from North 250 cpm 2
door, 0.8' above floor (1,250 dpm per 100 cm )
B On East Wall, 12' from North 300 cpm 2
door, 0.8' above floor (1,500 dpm per 100 cm )
C On East Wall, 8.8' from South 1,550 cpm 2
wall, 3.1' above floor (7,750 dpm per 100 cm )
D On East Wall, 6.8' from South 2,050 cpm 2
wall, 4.1' above floor (10,250 dpm per 100 cm )
l E
On East Wall, 4.7' from South 10,000 cpm 2
wall, 4.1' above floor (50,c00 dpm per 100 cm )
F On East Wall, 2' from South 1,050 cpm 2
wall, 0.8' above floor (5,250 dpm per 100 cm )
G On East Wall, 3' from North 15,000 cpm 2
door, 8.7' above floor (75,000 dpm per 100 cm )
I H
On West Wall, 5.8' from door, 850 cpm 2
0.8' above floor (4,250 dpm per 100 cm )
I On West Wall (concrete under,
550 cpm 2
baseboard), 9.5' from door, (2,750 dpm per 100 cm )
0.8' above floor J
On West Wail (concrete under 750s 2
baseboard), 2.8' from door, (3,750 dpm per 100 cm )
0.8' above. floor K
On West Wall, l' from South 350 cpm 2
Wall, 4' at we floor (1,750 dpm per 100 cm )
L On West Wall, 2.7' from South 1,050 cpm 2
Wall, 6.7' above floor (5,250 dpm per 100 cm )
M On West Wall, 3.6' from South 450 cpm 2
Wall,1.5' below ceiling (2,250 dpm per 100 cm )
N On West Wall, 5.3' frein South 150 cpm 2
Wall,1.5' below ceiling (750 dpm per 100 cm )
l Location Noted Meter Reading on Figures I & II Description of Location with Background Subtract 0
On South kall, 22.7' from West 850 cpm 2
Wall, 0.8' above floor (4,250 dpm per 100 cm )
P On South Wall, 8.1' from West 250 cpm 2
Wall, 0.8' above floor (1,250 dpm per 100 cm )
Q On ground in crawl space under 150 cpm 2
porch (750 dpm per 100 cm )
2.
Wipe Survey with No. 42 Whatman filter paper and NRC:RV gas flow proportional counter.
Results in 2
Location Noted dpm per 100 cm on Figure 1 Description of Location Alpha Beta-Gamma G
On East Wall, 3' from North 0
173 door, 8.7' above floor 0
On South Wall, 22.7' from West 0 116 Wall, 0.6' above floor P
On South Wall, 8.1' from West 0
179 Wall, 0.8' above floor i
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