ML20127N841

Safety Evaluation Supporting Order Authorizing Dismantling of Facility & Disposition of Component Parts,Per 850114 Application

ML20127N841
Person / Time
Site:	05000187
Issue date:	05/28/1985
From:	NRC
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Shared Package
ML20127N791	List: ML20127N789 ML20127N805 ML20127N819 ML20127N841 ML20127N866
References
NUDOCS 8507020219
Download: ML20127N841 (7)

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UNITED STATES 3 o NUCLEAR REGULATORY COMMISSION t tj WASHINGTON, D. C. 20S55

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Safety Evaluation Supporting Order Authorizing Dismantling of Facility and Disposition of Component Parts Northrop Corporation Research Reactor Facility Operating License R-90 Docket No. 50-187 1.0 Introduction By application dated January 14, 1985, as supplemented, Northrop Corporation (NC) requested authorization to decontaminate and dismantle the 1 Mw TRIGA Research Reactor, to dispose of its component parts in accordance with the proposed plan, and to tenninate the

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Facility Operating License R-90. Following the reactor shutdown in ,._

December 1984, the fuel was removed from the core tank and placed in storage. All fuel has since been shipped to other TRIGA facilities for use.

2.0 Facilicy Description The Northrop reactor facility is located at the Northrop-Hawthorne Facility in the city of Hawthorne, in Los Angeles County, California.

The reactor is a pool-type TRIGA Mark F licensed to operate in the steady-state mode at a power level of one megawatt, and in the pulsed mode with reactivity insertions of 3.005. During operation, the reector utilized 86 stainless steel-clad standard TRIGA fuel elements with U-235 enrichment cf less than 20%. The core is located approximately 17 feet below the surface of the reactor pool and is supported from a mobile bridge by a cylindrical shroud. A schematic of the reactor is shown in Figure 2.1.

The entire reactor complex is located above ground, with ground level access to the dry exposure room, the horizontal beam ports, and the pneumatic transfer tubes. The building housing the reactor has approximately 10,000 square feet of floor space (see Figure 2.2.).

A cobalt-60 scurce of approximately 1800 curies is located within the 7 feet wide by 7 feet long by 10 feet high hot cell that is contiguous with the reactor core biological shielding. The cobalt source. has bee-moved out of the hot' cell to a temporary shielded area in another building awaiting a decision on its final disposition. Thrtobal t facility is licensed by the State of California. However..as it has 7

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common walls with the reactor facility, dismantling of the hot cell is part of the plan for dismantlino and decontaminating the reactor complex. With the cobalt removed from the hot cell, there.should be no residual activity.

A FEBETRON-705 Flash X-ray machine that was located in a 12 feet wide by 24 feet long roon has been removed from the building. (See Figure 2.2). As this unit is not included in license R-90, and is physically removed from the reactor, it will heve no effect on the fulfillment of the order for dismantling and decenmissinning of the NRC-licensed TRIGA fccility (including the hot cell).

3.0 Discussion Reactor Facility License (R-90) was granted to the Northrop Corporation in March 1963. The averaae ennual use has been about 55 megawatt-hrs per year.

The selected decommissioning option is decontamination (DECON) with subsequent release of the facility for unrestricted use. The licensee- "

has agreed that the radiation levels for unrestricted use will be 5 /hr at one meter from the surface (see Section 4.4 below). The collective dose equivalent to the staff and public for the decommissioning operation is estimated to be less than 5 person-rem.

A radiochemistry laboratory with radiochemical fume hoods, hot storage wells, hot held tanks, and associated chemical laboratory equipment is located within the reactor building. A machine shop is also located in the building. These will be dismantled and decontaminated.

There has been no uncontrolled release of radiation to the environment during the operating history of the Northrop reactor. There has been no fracture of, or leakage from, the fuel rods. One chemical spill in the radiochemistry laboratory was reported. This involved a short half-life flourine solution in 1070. The spill was cleaned up and the laboratory has been in use since that time.

4.0 Evaluation Northrop proposes to dismantle the facility in accordance with their dismantling plan. They intend to decontaminate the facility below the radiation ard contamination levels of Regulatory Guide 1.86 and staff positions, as addressed in Section 8.2 of this safety evaluation, for unrestricted access and use. The non-radioactive components may be utilized in other projects within the Northrop complex or disp;osed of as scrap. Contaninated reactor components and rubble will te disposed of at a licensed burial facility, transferred to the Department of Energy, or retained for use under the State of California, license.

d The staff has reviewed the Northrop plan to dismantle the TRIGA reactor facility, dispose of its component parts and radioactive material and decontaminate the facility. The review considered the management responsibilities and commitments; the relevant regulatory guides, the health physics program including procedures, equipment, instrumentation, survey techniques, training, and personnel dosimetry; the waste disposal; and the final survey. These functions and activities, except for the final survey, were ongoing during operation of the TRIGA reactor and will be maintained in appropriate scope during its dismantlement. They are described in the following sections.

4.1 Sources ,

With the fuel shipped offsite to other users, the only residual activity inthecorecompgntsisfromactivationproducts. The other sources include the two AmBe neutron sources of about 7.5 curies each and miscellaneous calibration sources totaling less than 1 curie. All sources have been moved out of the reactor building awaiting

_ decisions on future disposition, r-Radioactive material from the reactor structure, components, filters, ggncrete,6gubble, etc will consist of less than 10 curies, primarily Co and Zn. It will be monitored, packaged and shipped, in accordance with applicable regulatory requirements, to an approved storage or disposal facility.

The reactor pool water, which has a low activation product inventory, has been drained and, upon approval of the Los Angeles County Sanitation District, will t.e discharged into the public sewer system.

. . The staff finds that the licensee's plans for disposition of sources of radioactivity associated with this operation are acceptable.

. 4.2 Health and Safety Management The radiation protection program for the dismantling and decontamination operations is an extension of the existing radiation protection program.

The organization for the dismantling and decontaminating the reactor facility has a health physicist, with a BS degree in physics and 16 years of health physics and reactor experience, who will recomend and enforce radiological safety policy. He will be responsible for assigning health physics technicians to specific tasks, implementing the environmental survey program, maintaining radiation exposure records and overseeing subcontractor health physics operations associated with the_ dismantling and decomissioning operations. The combined Northrop and contractor health physics staff will consist of seven people, among whgm will be a certified health physicist and three senior health physics technicians.

A Corporate Radiation Committee, responsible for monitoring and assuring safe operations, and a Dismantling Subcommittee, which is responsible for the review and approval of proposed dismantling operations and safety standards, will meet monthly during decommissioning to review progress.

It is Northrop policy that all operations will be planned and executed to conform to Comission regulations and appropriate Regulatory Guides and to maintain occupational exposure to as low as is reasonable achievable (ALARA) levels.

4.3 Dose Comitment The licensee has estimated that the collective dose equivalent expected for the entire dismantling and decontamination operation will be less than 5 person-rem. The collective dose to workers in the Northrop facility, the adjacent industrial complex and any residential areas should be much less. This estimate is based on the expected levels of radioactivity and related radiation levels from all sources; the manner.

in which experienced and well-trained workers will be performing their__

tasks in the expected radiation fields; review of all procedures by the' Dismantling Subcomittee and the Corporate Radiation Committee and use of enclosures, controlled atmosphere and filtration systems to control movement of radioactive dust. These items, among others described by the licensee, will assure that collective exposures will be ALARA, and are found to be acceptable to the staff.

4.4 " Unrestricted Use" Release Criteria The staff position for release for unrestricted use or unrestricted access is found in Regulatory Guide 1.86, Table 1, or may be satisfied by meeting an exposure rate limit of less than 54.R/hr above natural background at 1 meter from any measured surface.

Alternatively, if it can be shown that the maximum radiation exposure to an individual would be less than the staff's recommended annual exposure limit of 10 mR/yr, considering potential occupancy in the vicinity of the radiation, then levels greater than SAR/hr would be acceptable. The licensee has comitted to these criteria.

4.5 Health Physics Instrumentation Continuing evaluation of the radiological statu:, of the facility will be carried out by health physics personnel during dismantling and clean-up procedures. Levels of radiation will therefore-be known at all times in areas where personnel are working. Portable monitoring equipment will include alpha, beta and gamma survey meters,-end gas and particulate airborne radioactivity monitors and samplett. All these monitors are calibrated quar,terly with sources traceable to NBS.

In response to a staff question on radionuclide identification of samples, the licensee plans to send swipes, core samples, scrapings and liquid samples to an independent certified laboratory for radionuclide identification.

Staff review indicates that the instruments to be used by the licensee during the dismantling and decontamination operation, and his plan for sample analysis are acceptable for use in a final termination survey to characterize the status of the reactor facility with respect to its unrestricted use.

9.0 Conclusion Based on the foregoing considerations, the staff concludes that the dismantling and decontamination operations can be conducted without undue risk to the health and safety of the public or workers, and without any significant impact on the public or the environment.

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Principal Contributors: Harold Bernard Seymour Block Dated: May 28, 1985 D

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