ML20238E736
| ML20238E736 | |
| Person / Time | |
|---|---|
| Site: | 07000734 |
| Issue date: | 08/25/1998 |
| From: | Asmussen K GENERAL ATOMICS (FORMERLY GA TECHNOLOGIES, INC./GENER |
| To: | Britz W, Gaskin C NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV), NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| References | |
| 696-2968, TAC-L31106, NUDOCS 9809020156 | |
| Download: ML20238E736 (8) | |
Text
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]O ~ lbY G 105 August 25,1998 696-2968 VIA OVERNIGIIT DELIVERY SERVICE Mr. Charles E. Gaskin Licensing Section 1/ Licensing Branch Division of Fuel Cycle and Safety and Safeguards, NMSS U.S. Nuclear Regulatory Commission Washington, DC 20555 and Mr. Wayne L. Britz Nuclear Materials Safety Branch 3 Division of Nuclear Materials Safety U.S. Nuclear Regulatory Commission Region IV 611 Ryan Plaza Drive, Suite 400 Arlington, Texas 766011-8064
Subject:
License No. SNM-696; Request for Concurrence with Anticipated State Release of Roof of General Atomics' Building 27
Dear Messrs. Gaskin and Britz:
As you are aware, General Atomics (GA)is in the process of decontaminating, and obtaining the release to unrestricted use, certain ofits facilities (i.e., facilities for which GA has no plans for conducting future activities involving the use of radioactive materials).
Most recently, GA completed the decontamination and fmal surveys ofits Building 27 (a.k.a.
Bldg. EA-1) that had housed GA's analytical-and radio-chemistry laboratories. The results of GA's extensive and comprehensive fmal radiation and contamination surveys, measurements, sampling, and analyses demonstrate conclusively that the this building meets the NRC-and State-approved criteria for release to unrestricted use. These results are being documented in a repon that is currently in preparation, and will be submitted to NRC later this year (by approximately the end of October)in suppon of a request for Building 27 to be released to unrestricted use and deleted from GA's license.
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j The predominant contaminant found in Building 27 was Cs-137, a State of California licensed radioactive material. In the process of decontaminating the building, GA removed the soft roofing material (e.g., tar, insulation, plastic sheeting and gravel) leaving only a bare metal roof.
y Now GA has a need for the roof to be made once again weather proof (e.g., re-tarred etc.) before the 1\\
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7 PDR ADOCK 07000734 C
PDR 3550 GENERAL ATOMICS COURT. SAN DIEGO, CA 921211194 PO BOX 85608. SAN DIEGO, CA 92186 5608 (619:455 3000
U.S. Nuclear Regulatory Commlulon August 25,1998 CAL-2968 Page 2 rainy season. Accordingly, under separate cover, GA has requested that the State of California Department of Health Services, Radiologic Health Branch release the roof of Building 27 to unrestricted use. In support of that request, GA prepared and submitted the enclosed report titled,
" Building 27 (EA-1) Metal Roof Radiological Survey for Release to Unrestricted Use." This report only addresses the results of surveys and measurements made on the roof and demonstrates that the roof does indeed meet the criteria for release.
The State has scheduled a visit to GA's site on Augt.st 27 and 28 to commence confirmatory surveys associated with this and other pending requests for releases.
While the predominant contaminant identified in Building 27 was a State licensed material, the building is identified in GA's SNM license. Accordingly, as mentioned above, GA will be requesting that NRC release this building to unrestricted use and delete it from GA's SNM-696 license.
The purpose of this letter is to request NRC concurrence with the anticipated State release of the bare metal roof of GA's Building 27.
In anticipation of your desire to confer with the California Department of Health Services, Radiologic Health Branch regarding this matter, the cognizant lead person is Dr. Roger Rogus. He
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may reached by phone at (916) 455-9444, or by e-mail at <rrogus@dhs.ca. gov >.
Ifyou should have any questions regarding the above, or the enclosed report, please contact me at (619) 455-2823, or Ms. Laura Q. Gonzales at (619) 455-2758. Your early attention to and consideration of this request is very much appreciated.
Very truly yours, Keith E. Asmussen, Ph. D., Director Licensing, Safety and Nuclear Compliance
Enclosure:
Report titled, " Building 27 (EA-1) Metal Roof Radiological Survey for Release to Unrestricted Use," dated August 24,1998.
cc:
Dr. D. Blair Spitzberg, Division of Nuclear Materials Safety, N'RC Region IV i
l
o August 24,1998 Page 1 of 2 Prepared by John Turner and Laura Gonzales Building 27 (EA-1) Metal Roof Radiological Survey for Release to Unrestricted Use Introduction Building 27 (EA-1) has been decontaminated and surveys show radiation levels criteria for release to unrestricted use. This survey report summarizes on performed on the metal roof after removal of the ventilation system, tar, insu sheeting and gravel.
This report is being prepared separately in order to obtain approval from the Stat (State) and the Nuclear Regulatory Commission (NRC) to repair the roof before The results demonstrate that the metal roofmeets the approved criteria for releas use.
Description (see Figures for Details)
The roof measures ~ 14 m x 36 m (~ 500 m ). It was covered (from the top 2
a 1.5 inch layer of gravel, a 1.0 inch layer of tar paper, a 1 inch layer ofinsulatio heavy black plastic sheeting which have been removed. The roofof the building galvanized, corrugated metal. Most of the roofimg material is being disposed of as rad waste, except for about 3/4 of the gravel which will be disposed of as non-radioacti State /NRC approval for disposition to the local (Miramar) landfill.
Release Criteria The applicable guidelines (taken from Guidelines For Decontamination of Facilitie Prior to Release for Unrestricted Use or Termination of Licenses For byproduct, S Nuclear Material, also known as "Decon-1" incorporated into both GA's State Radioac License and GA's Site Decommissioning Plan) for residual contamination on building s{
beta / gamma emitters (including Cs-137 and Co-60) are:
5,000 dpm/100 cm, averaged over 1 m area 2
2 15,000 dpm/100 cm, maximum in a 100 cm area 2
2 1,000 dpm/100 cm, removable activity 2
Survey Plan The metal roof was surveyed as an " unaffected area"in accordance with a written plan t
" Supplemental Building 27 (EA-1) Roof Survey Plan" dated July 27,1998 (attachment Contamination in the building was restricted to beta / gamma emitters (Cs-137 was the predominant contaminant). Therefore, no alpha surveys of the roof were performed (alph surveys inside the building were performed).
EAIROOF898 i
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Page 2 of 2 Instrumentation (1)
For scanning - The Ludlum Model 2221 (S/N 73701) Ratemeter with the Ludlum Model 2
43-37 (S/N 093600) gas proportional (434 cm ) Beta detector, consisting of four linear ranges (0-500,000 & one log 50-500,000) was used. The calibration due date for this radiological instrument with corresponding probe is 12/30/98 and the efficiency is 2
24.13%. The active probe area is 434 cm. The detector and ratemeter are combined and mounted on a roll cart. The instrument features a static-flow system, quick connects, a portable gas bottle and a means to adjust the height of the detector from the floor for optimum performance. Ten background measurements for this instrument / probe were obtained from metal surfaces located in Building 13 and typically ranges from 1080-1180 epm.
1 I
(2)
For beta fixed measurements - The Ludlum Model 2221 (S/N 148436) Ratemeter with 2
the Ludlum Model 43-68 (S/N 120477) 100 cm gas flow proportional beta counter, consisting of four linear ranges (0-500,000 & one log 50-500,000) was used. The calibration due date for this radiological instrument with corresponding probe is 11/03/98 and the efficiency is 27.06%. Ten background measurements for this instrument / probe were obtained from metal surfaces located in Building 13 and consisted of an average of 2
575 cpm 14 counts per two (2) minutes with an MDA of 211 dpm/100cm,
(3)
For removable contamination surveys - A Canberra Model 2400 low level alpha / beta counting system was used to count the wipes for removable contamination.
Results (1)
Beta Floor Monitor Scans - In addition to scanning at least 10% of the surface, twenty-2 two (22) readings were recorded with the floor monitor (434 cm detector); results ranged from i 100 to 1300 cpm. Ten background measurements for this instrument / probe were obtained from metal surfaces located in Building 13 (a non-impacted building on the GA site); results ranged from 1080-1180 cpm. See Figure 1.
2 (2)
Fixed B Measurements - Twenty-two (22) measurements conducted with the 100 cm beta monitor produced results ranging from 670 to 708 counts per two minutes. The 2
maximum reading of 708 counts per 2 minutes = 246 dpm/100 cm (using a background of 575 counts in 2 minutes and an efficiency of 27.06%); well below the average 5,000 2
dpm/100 cm limit. See Figure 2 for locations and results of the measurements.
1 (3)
Removable Measurements - Fifteen (15) wipes were taken on the roof. The alpha and the i
2 i
beta removable activity levels were all < 10 dpm/100 cm. See Figure 3 for approximate locatio.ts of wipes.
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July 27,1998 i
111a.I h. g John Tumer Approved By:
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Supplemental Building 27 (EA-1) Roof Survey Plan Backaround and Purpose The roofing materials (i.e., gravel, tar and insulation) have been removed or will be removed from the building. The remaining corrugated, galvanized metal roof and metal HEPA system enclosure (barrier) must be surveyed in order to ensure that the radiological conditions satisfy the NRC and State of CA guidelines for release to unrestrimed use.
Classification The corrugated, galvanized metal roof was covered with a 1.5 inch layer of gravel, a 1.0 inch layer of tar paper and a layer of heavy black plastic sheeting. The exposed galvanized metal roofing appears as new metal beneath these layers due to its protection by the overlying layers. The HEPA system enclosure (barrier) is not expected to be contaminated. Consequently, the corrugated metal mof and HEPA barrier will be 1
classified as an " unaffected" area. No residual contamination is expected to be found. If contamination is discovered in the unaffected area at 2 75% of the guideline limits, an evaluation will be performed and the classification reevaluated accordingly.
Surveys All surveys will be conducted only after all of the roofing material has been removed from the roof and only after the roof has been cleaned of all debris.
The roof encompasses approximately 500 m. Therefore, a minimum of 30 measurements 2
will be taken and scans will be conducted on 10% of the roof's surfam and HEPA system barrier. Surveys will be conducted for beta activity only.
Roof Area and HEPA System Barrier (1.) No gridding.
(2.) No masslin surveys.
(3.) Ten percent (10%) scans only; take the scans with the 434 cm Eas flow 2
proportional detector with the Model 2221 ratemeter.
(4.) Measurements, a total of 30: (a.) take a minimum of 15 fixed measurements; take a 2 minute count using the 100 cm gas flow proponional detector with the Model 2221 2
ratemeter, and (b.) take 15 smears.
(5.) No exposure rate measurements (microR readings).
l Documentation The radiological survey conducted must be documented to a worksheet/ logbook and on a drawing showing the appropriate locations surveyed. The documentation must include the results of the measurements (including units), the technician's printed name and signature, date, instrument (s) used (including the model and serial number of both the ratemeter and the detector), calibration due date, % efficiency, background readings (if applicable) and any other pertinent information.
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