ML20002C356
| ML20002C356 | |
| Person / Time | |
|---|---|
| Site: | 07000687 |
| Issue date: | 12/05/1980 |
| From: | Voth M UNION CARBIDE CORP. |
| To: | NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| References | |
| 18057, NUDOCS 8101100157 | |
| Download: ML20002C356 (8) | |
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fii Washington, D.C. 20555 70'.24(a)]
Subject:
Request for Exemption Pertaining to 10 R Par
Dear Sir:
A Region 1 NRC inspector in a September 4, 1980 inspection report questioned the compliance of our criticality monitoring program with.
respect to 10 CFR 70.24.
In our November 5, 1980 response, we stated our; position that all the requirements are satisfied, but that ali exempt-ion woulo be requested for those parts of our operation where thg requi,rgment.E is inappropriate.
The folloaing information addresses that subject-Blong '
with two other subjects raised in the inspection.
Since SNM-639 authorizes greater than 700 g of enriched uranium 235 at our Sterling Forest facility, 10 CFR 70.24(a) requires a criticality monitoring system "in eacn area in which sucn licensed special nuclear material is handled, used, or stored".
Due to factors discussed in the safety evaluation below, criticality monitoring is only appropriate in that portion of the facility where material is in solution form. An exemption is therefore requested for areas where material is nandled, used, or stored in dry oxide form.
Attached is a document entitled "A. Hot Laboratory Monitoring System."
inis document updates and replaces in its entirety a document by the same title attached to our June 13, 1973 submittal. This document provides an up-to-date description of the monitoring system.
Exemption Requested It is requested that the existing Condition 9 of License SNM-639 be amended by including reference to this letter, making Condition 9 in its I
entirety read:
"9. The special nuclear material is for use in accordance with the statements, representations and conditions specified in tne l
licensee's applications dated April 28 and May 21, 1969; November 5, 1970; February 8, June 13, June 29, and August 13, 1973, May 28, 1974; Feoruary 11, 1975; August 12, 1976; May 3, Octooer 13, and Novemoer 17,1978; June 2, Novemoer 26, and i
December 5, 1980."
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< It is furthermore requested that the existing Condition 13 of License 5:tM-639 ce amendeo by adding a second exempt condition, making Condition 13 in its entirety read:
"13.
Pursuant to paragraph 70.14(a) of Title 10, Code of Federal Regulations, Part 70, the licensee is nereby exempt from the requirements of Subparagraph 70.24(a) with respect to special nuclear material neld under tnis license and being used (1) in hot cells as described in his letter dated June 29, 1973, or (2) in areas wnere material is allowed only in the fann of dry oxide or assay samples, as described in his letter dated December 5, 1980."
Safety Evaluation Section 9 of Materials and Plant Protection Amendment, MPP-3, to license SNM-639 restricts the quantity of unirradiated enricned uranium in the facility to less than 5,000 g U-235. The single parameter limit for nuclear criticality safety (ANSI Standard N16.1-1975, Nuclear Criticality Safety in Operations with Fissionable Materials Outside Reactors) is as follows:
760 g U-235 for uniform aqueous solutions reflected by an effectively infinite thickness of water.
20,100 g U-235 for metal units reflected by an effectively infinite thickness of water. Nuclear Safety Guide, TID-7016, Revision 2, shows that the subcritical spnerical mass is approximately the same wnetner the material is in tne form of metal or dry oxioe.
Various physical limitations and administrative Controls restrict the quantity of special nuclear material in any defined area of the facility to a small fraction of the facility limit. However, if the entire 5000 g quantity of unirradiated special nuclear material for snich the site is licensed were in oxide form in one location, it would still be significantly less than the single parameter limit. All areas where material is handled, used, or stored are above grade, so that flooding and dissolution are not credible events.
It is, therefore, reasonable to grant an exemption for the criticality monitoring requirements of 70.24(a) for those areas where special nuclear material is only allowed in an oxide form.
Tne fact that Section 9.1 of License SNM-639, as referenced above, refers to unirradiated material does not cnange tnis conclusion. Material in tne facility is in one of the following forms:
.. FORM LICENSING CONSIDERATION Liquia material in plating process.
Subject to 10 CFR 70.24(a) requirements.
Dry oxiae or assay samples.
Subject of Inis exemption request.
Targets in tne reactor or transfer Under water and not subject to canal.
Material in process in the hot cells. Considered by the existing Condition 13 of SNM-639.
Material packaged for transportation. Packaged per Part 71, and tnerefore not subject to 10 CFR 70.24(a).
The potential for the unirradiated inventory of U-235 interacting with irradiated material has been evaluated. Unirradiated material is separated from the irradiated material by four feet of concrete or a greater thickness of water. Unirradiated material is therefore ae-coupled from 1rradiated material.
Liquid material in the plating process is confined to the second floor of the Hot Lab wnere criticality monitoring is provided. The only personnel access and egress points are a remote indoor stairwell and emergency exits to the outdoors.
In addition to being pnysically separated by walls ano structures, the remote means of access to the facility is such that material will not be inadvertently taken to other areas of the facility. The physical layout and assembly process provide a high degree of assurance that material in solution form will not leave the designated, monitored area and enter those areas restricted to SNM in dry oxide form.
The recuested amendment also seeks an exemption from criticality monitoring in those areas where assay samples are processed.
If numerous dssay Vials are placed on a laboratory Counter in a closely packed array, the single parameter limit of 4.6 cm thickness for an infinite aqueous slab applies per ANSI N16.1-1975. Typically, assay samples are dispersed in small quantities per vial in an array that is much less reactive than the infinite slab. There is no need or incentive to have a major portion of the licensed inventory tied up in assay samples, as would be the case if the 760 g single parameter limit were approached. Assay samples, by their nature, require 1 total of only a few grams in the lab.
It is, i
tnerefore, reasonable to include assay samples in the exemption, regaraless of the pnysical form.
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Designation of New Storage Area MBA 3 of tne facility is Reactor Operations. Prior to placing a finished target in the reactor it is welueo in a seconaary encapsulation. Tnis step is done in the machine shop by one of the M3A 3 custodians. Tne shop has recently oeen postea as a location wha x 5.*Nial nuclear material is autnorizea in quantities of up tt jed gr +,s in oxide form.
aaterial is only kept in this area while tnG i:5g$ts ("e being
- encapsulated; there is no extended storagt.
ihile undergoing this process, the material remains on the inver,!:rf of tne storage cabinet from wnich it was taken and to wnich it will be returned.
Alpha Contamination Statements were made in submb.tals dated April 28, 1969 and again on November 5, 1970 to the effect tnat when nandling unencapsulated special nuclear material, floor clean-up would commence upon finding alpna contanination in excess of 100 dpm per 100 cm2 of floor area.
Experience over the past decade has snown this criteria to be overly conservative and unduly restrictive.
Work with SNM is conducted daily in the target plating laboratory. Even with frequent cleaning it is not practical to maintain removable alpna contamination levels below 100 dpm per 100 cm2 Tne following criteria is proposed to supercede all previous statements regarding alpha contamination:
Aloha Surface Contamination Limits for Controlled Areas Removaole Surface Action to ce Taken by Health Physics Contamination Threshhold when eitner Average or Maximum Smear in dpm Above Background Results are Exceeded 30 dpm avg /75 dpm max Inform Supervisor.
300 apm avg /750 dpm max Post area, requiring protective clothing, and inform Supervisor.
1500 dem avg /3750 dpm max Post area, requiring protective clothing, and inform Supervisor of need for immediate clean-up.
Note 1.
Wipe samples over a 100 cm2 area shall be taken eacn working day and analyzed for alpha contamination in areas wnere unencapsulated alpna emitters are oeing handled.
Note 2.
The maximum dpm value is determined from tne nignest single smear. Tne dpm average is the average dp:n of the smears taken in a particular area.
. The above criteria are part of the Agreement State license for the facility.
It is demonstrated to be adequate in that the continuous air sampling performed in tnese laboratories has never detected rignificant airborne uranium originating from floor contamination.
i Pursuant to 10CFR 170.31, a check in the amount of $1400.00 is attached for processing this amendment.
If we can be of assistance to you in your review, please feel free to call.
Yours very truly, k
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Marcus H. Voth Manager, Nuclear Operation cc: George H. Smith, Chief Fuel Facility & Materials Safety Branch Region 1, U.S. Nuclear Regulatory Connission Att.
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A-1 A.
HOT LABORATORY MONITORING SYSTEM The Health Physics Supervisor is responsible for all pnases of Health Physics. He supervises the activities of Health Physics tecnnicians.
1.
Health Physics Training All personnel working with radioactive material in the Hot Lab receive basic radiation safety training. This initial radiation safety instruction is supplemented by on-the-job training during each new operation.
2.
Personnel Monitoring All personnel working in the Hot Lab wear a film badge and two pocket ionization chambers. The pocket cnambers are read daily and the film badges are evaluated bi-weekly by an approved commercial laboratory.
Urinalyses on all Hot Lab personnel working witn radioactive materials are made on a routine basis at least once each year.
Additional samples will be taken as recommended by the Healtn Physics Supervisor.
3.
Instruments and Equipment All radiation detection and monitoring equipment is set and kept in proper operating condition.
g a.
Radiation Detection and Monitoring Radiation detection instruments available for monitoring include at least 5 Ion Chamber survey meters with range up to 50,000 mr/hr, 2 Geiger Detectors with range up to 20 mr/hr,1 Alpha Scintillation Counter, 1 End Window G.M. Counter with Sealer, and 1 Multichannel Analyzer with NaI Scintillation Detector.
Portable radiation detection equipment such as cutie-pies, G-M survey meters, and alpha detectors are located at various points in the area. A Hand and Foot Counter is near the main exit from the Hot Lab; it is used by visitors and personnel before leaving the building.
b.
Area Monitors-Within the Hot Lab at various points, monitrons are provided to detect local increases in radiation levels and to give alarms.
These monitors have-audio ano visual alarms at the local po.'nt and at the main monitron control panel in the operating area of
A-2 the Hot Lab.
(A similar system monitors SNM-639 material while in tne reactor building, the main monitron control panel for that area ceing in the reactor control room.) Set points for the monitrons in occupied areas are normally set at 5 mr/hr to 10 mr/hr.
Two monitrons on the second floor of the Hot Lab are used for a criticality monitor pursuant to 10 CFR 70.24(a). All extremities of the area are within 120 feet of each of the monitors. The maximum intervening shielding is a six inch hollow concrete block wall. The high level alarm set points are set between 5 mr/hr and 20 mr/hr, proviaing capability to detect a criticality which generates radiation levels of 300 rems per hour one foot from the source. TF location of intervening shielding has been evaluated to verify that a criticality of that magnitude at all possiole locations will be detecteo. In the event of a criticality of this magnitude, both monitrons will trip and alarm. The simultaneous trip of these two monitrons will initiate an automatic evacuation alarm. Two cnannels are used rather than one to avoid false alarms caused by movement of radioactive material near a monitron. Each detector is designed to fail in the tripped condition. To clear a criticality monitor alarm whicn is known to be the result of other factors (e.g., monitron failure, equipment maintenance, or movement of radioactive material), the set points may be changed from those specified above if all special nuclear aaterial is secured and operating personnel are vacated from the area.
c.
Constant Air Monitors Two constant air monitrons are located in the Hot Lab. The monitors can be set to draw air (via a vacuum pump) past filter 3
paper at a flow rate ranging from 1 to 10 ft / min. A G-M tube is located above the filter paper and measured activities are continually recorded.
d.
Stack Monitors Tne exhaust air from both the Reactor and Hot Lab are continuously monitored for radioactive particulate matter '.nd for gaseous activity. This monitor is equipped with a recorder and alarm circuits to indicate high activity or equipment failure.
It is checked on a routine basis at least once a day.
An accumulative weekly sample is analyzed for alpna activity.
e.
Hot Lab Evacuation System In the event of unexplained alarms from (a) two area monitors, (0) an area monitor and a constant air monitor, or (c) an area monitor and the stack monitor, the evacuation alarm will be souncad. This alarm is normally sounded manually by means of
c A-3 push buttons located throughout tne facility. The alarm sounds from units located in every major area of the Hot Lab and is easily neard in all locations. All personnel are instructed in the use of the system.
Tne simultaneous trip of the two monitrons used to detect criticality on the secono floor of the Hot Lab will initiate the evacuation alarm autcmatically.
f.
Wipe Tests Wipe tests are made of the floors daily and analyzed for beta, gamma, or alpha activity as appropriate. Wipe tests are done on all sealed sources semiannually. All equipment and materials require Health Physics' approval before being removed from a controlled area.
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