ML18331A396
| ML18331A396 | |
| Person / Time | |
|---|---|
| Site: | University of Lowell |
| Issue date: | 02/05/1998 |
| From: | Michaels T Office of Nuclear Reactor Regulation |
| To: | Kegel G Univ of Massachusetts - Lowell |
| Helvenston E, 415-4067 | |
| References | |
| TAC M89847 | |
| Download: ML18331A396 (38) | |
Text
.. Redacted for Public Release February 5, 1998 Dr. Gunter Kegel Director of Radiation L.aboratory University of Massachusetts Lowell One University Avenue Lowell, Massachusetts 01854
SUBJECT:
GAMMA CAVE FACILITY (TAC NO. M89847)
Dear Dr. Kegel:
Upon further review, we have determined that the Gamma Cave facility, contiguous with the University of Massachusetts Lowell Research Reactor, is not a facility which would be within the envelope of faclllties covered by the regulation in 10 CFR Part 36 *ucenses and Radiation Safety Requirements for lrradiators." Tha rationale for this concluslon is documented In the enclosed safety evaluation. This safety evaluation reviews the adequacy of the Access Controls for the Gamma Cave faclllty and surrounding area to meet the requirements of 10 CFR 20.1601 and 20.1602, *control of Access to High Radiation Areas* and "Control of Access to Very High Radiation Areas" respectively. We have determined that the Access Controls meet the requirements of these regulations and that they are acceptable.
If you have any questions, please call me at 301-416-1102.
Sincerely, ORIGINAL SIGNED BY:
Theodore S. Michaels, Senior Project Manager Non-Power Reactors and Decommissioning Project Directorate Division of Reactor Program Management Office of Nuclear Reactor Regulation Docket No.60-223
Enclosure:
As stated cc w/enclosure:
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Redacted for Public Release
.. February 5, 1998 Dr. Gunter Kegel Director of Radiation Laboratory University of Massachusetts Lowell One University Avenue Lowell, Massachusetts 01864
SUBJECT:
GAMMA CAVE FACILITY (TAC NO. M89847)
Dear Dr. Kegel:
Upon further review, we have determined that the Gamma Cave facility, contiguous with the University of Massachusetts Lowell Research Reactor, is not a facility which would be within the envelope of facilities covered by the regulation in 10 CFR Part 36 *ucenses and Radiation Safety Requirements for lrradiators.
- The rationale for this conclusion Is documented in the enclosed safety evaluation. This safety evaluation reviews the adequacy of the Access Controls for the Gamma Cave facility and surrounding area to meet the requirements of 10 CFR 20. 1601 and 20.1602, *control of Access to High Radiation Areas* and *control of Access to Very High Radiation Areas* respectively. We have determined that the Access Controls meet the requirements of these regulations and that they are acceptable.
If you have any questions, please call me at 301-415*1102.
Sincerely, ORIGINAL SIGNED BY:
Theodore S. Michaels, Senior Project Manager Non-Power Reactors and Decommissioning Project Directorate Division of Reactor Program Management Office of Nuclear Reactor Regulation Docket No. 50-223
Enclosure:
As stated cc w/enclosure:
See next page DISTRIBUTION:
E-MAIL HARD COPY TBurdick TDragoun Docket File 50-223 JRoe PDoyle MMendonca PUBLIC SWeiss CBassett WEresian EHylton POND r/f AAdams $Holmes Plsaac PDND:PA.t.
TMichael'7"' SWeiss 1f11 /98 1 ,-J./98 '1-1Sf98 OFFICIAL RECORD COPY C JMENT NAME: G:\SECY\MICHAELS\L*KEGEL Redacted for Public Release
Redacted for Public Release UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D,C, INII OIIOt February 5, 1998 Dr. Gunter Kegel Director of Radiation Laboratory University of Massachusetts Lowell One University Avenue Lowell, Massachusetts 01854
SUBJECT:
GAMMA CAVE FACILITY (TAC NO. M89847)
Dear Dr. Kegel:
Upon further review, we have determined that the Gamma Cave facility, contiguous with the University of Massachusetts Lowell Research Reactor, Is not a facility which would be within the envelope of facllities covered by the .regulation in 10 CFR Part 36 "'Licenses and Radiation Safety Requirements for lrradiators * ., The rationale for this conclusion is documented in the enclosed safety evaluation. This safety evaluation reviews the adequacy of the Access Controls for the Gamma Cave facility and surroundinQ area to meet the requirements of 10 CFR 20.1601 and 20.1602, "'Control of Access to High Radiation Areas ., and "'Control of Access to Very High Radiation Areas" respectively. We have determined that the Access Controls meet the requirements of these regulations and that they are acceptable.
If you have any questions, please call me at 301-416-1102.
Sincerely, Theodore S. Michaels, Senior Project Manager Non-Power Reactors and Decommissioning Project Directorate Division of Reactor Program Management Office of Nuclear Reactor Regulation Docket No. 50-223
Enclosure:
As stated cc w/enclosure:
See next page Redacted for Public Release
Redacted for Public Release University of Massachusetts Lowell Docket No.60-223 cc:
Mayor of Lowell City Hall Lowell, Massachusetts 08162 Mr. Lee H. Bettenhausen Nuclear Reactor Supervisor University of Massachusetts Lowell One University Avenue Lowell, Massachusetts 01864 Office of the Attorney General Environmental Protection Division 19th Floor One Ashburton Place Boston, Massachusetts 02108 Redacted for Public Release
Redacted for Public Release UNITED STATES NUCLEAR REGULATORY COMMISSION WAIHINGTON, D.C. a111 *1 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION FOR THE GAMMA CAVE FACILITY AT THE UNIVERSITY OF MASSACHUSETTS LOWELL FACILITY OPERATING LICENSE NO, B-J 25 POCKET NO. 50-223 1.0 LNIBPPUCT!ON The University of Massachusetts Lowell (UML or licensee) reactor license was amended on January 15, 1982 (Amendment 5) to permit possession and use of a Cobalt-60 source in quantities not to exceed 1,500,000 curies at any one time. The UML license was renewed on November 21, 1985, wherein the Cobalt-60 source was reviewed and retained in the license. However, an in-depth review of the access control requirements for access to the beem emanating for the source into a small enclosure, known as the Gamma Cave, was not developed in the records.
The Cobalt-60 sources are in the form of stainless-steel-covered strips, each about 10 in.
long by 1 in. wide by 0.25 in. thick, that are mounted in stainless steel racks, which are stored in specially designated crates. They are stored at the bottom of the reactor pool in the northern end of the pool. To use the sources, a crate of cobalt racks is placed on a work platform 10 feet under water, and the rack(s) for irradiation is(are) manually moved from the work platform to the source holder mounted on the pool side of the Gamma Cave window. The Gamma Cave window is an opening in the east end of the pool covered by an aluminum plate 2 ft. by 2 ft. The Gamma Cava is a concrete enclosure with dimensions as shown in figure 2 of Attachment 3. It is seen that it is a small enclosure 8 ft. by 7 ft. by 8 ft. in size. Figure 4.1 of Attachment 6 shows the Gamma Cave's location with regard to the reactor pool. The source strength passing through the window into the Gamma Cave depends on the number of cobalt strips placed in the source holder in front of the window.
The radiation levels in the Gamma Cave can exceed 5 grays per hour at 1 meter from the surface that the radiation penetrates, thus classifying it as a very high radiation area in accofdance with 10 CFR Part 20.
The Nuclear Regulatory Commission (NRC) amended its regulations by establishing a new Part 36 on February 9, 1993, 58 FR 7715, to specify radiation safety requirements and licensing requirements for the use of licensed radioactive materials in lrradiators. lrradiators use gamma radiation to irradiate products to change their characteristics in some way. The NRC staff's original approach was to assume that the Cobalt-60 configuration at UML had to meet the regulations in 10 CFR Part 36, and the staff requested that the licensee submit exemptions to the sections in Part 36 that were not complied with. However, upon further review, it was determined that the intent of Part 36 was not meant to apply to research and 9802230288 980205 PDR ADOCK 05000223 P PDR Redacted for Public Release
Redacted for Public Release test reactors (see reference and enclosure 1). The Cobalt-60 source, as it is applied at UML, can be considered to be another beam emanating from the reactor pool into a volume which Is small (the Gamma Cave) and, therefore, the access controls to that volume should be protected In accordance with the requirements of 10 CFR 20.1601 and 20.1602.
Since the staff's original approach to review the Gamma Cave against the requirements of 10 CFR Part 36, the licensee responded with requests for additional Information in letters dated July 12, 1996 as supplemented on October 31, 1996, May 9, 1997 and December 30, 1997. The licensee submitted information, which Is included in the following attachments.
- 1. A detailed analysis of conformance to Part 36 (Attachment 1).
- 2. Gamma Cave Operations (Attachment 2).
- 3. Description of Gamma Cave experimental setup (Attachment 3).
- 4. Gamma Cave interlock system (Attachment 4).
- 5. Fire Hazard Analysis.
These attachments are included herewith as background to this safety evaluation report.
2.0 EVALUATION The control of access to a high radiation area is in 10 CFR 20.1601 and, in section (a) of that regulation, it requires that access be controlled by one or more of three features.
Section (a)(2) reads as follows:
- A control device that energizes a conspicuous visible or audible alarm signal so that the Individual entering the high radiation area and the supervisor of the activity are made aware of the entry."
The control of access to a very high radiation area is in 10 CFR 20.1602 and reads as follows:
"In addition to the requirements in Section 20.1601, the licensee shall institute additional measures to ensure that an individual is not able to gain unauthorized or inadvertent access to areas in which radiation levels could be encountered at 500 rads (5 grays) or more in an hour at 1 meter from a radiation source or any surface through which the radiation penetrates.*
There are two barriers that have to be opened to enter the Gamma Cave, i.e., the Access Corridor and Gamma Cave doors. The Access Corridor door leads into an area which is a high radiation area when Cobalt-60 sources are placed in front of the Gamma Cave windoH (see Attachment 3, Figure 2). Normally, both the Access Corridor and Gamma Cave doors are closed and mechanically locked. When the Cobalt-60 sources are in front of the window, both these doors will have been electrically latched so now there would be two locks on each door. These locks would preclude someone from gaining access to the Gamma Cave.
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Redacted for Public Release Assume there is a single failure whereby the electrical latch on the Access Corridor failed to shut. Also, assume that someone ignored procedures end attempted to open the mechanical lock on the Access Corridor door (the key to the Access Corridor is kept in the control room two floors above the Access Corridor). As the door is opened the K1 relay would deenergize (see schematic in Attachment 4) and the K1A contact would close. With K1A closed, K2 is energized and contact K2A closes, which activates the Danger Horn. The Danger Horn can be heard throughout containment, including the third floor, where the supervisor of the activity would be made aware of the entry into the Access Corridor.
Thus it is seen that for one to enter the Access Corridor, procedures would have to be ignored (see Attachment 2, Standing Order 110), the gate solenoid would have to be defective and the mechanical lock would have to be opened after ignoring the displays on the Gamma Cell Monitor System (see Attachment 3, Figure 3), the gate switch (which is normally crosed and opens when the Access Door is opened, see Attachment 4, schematic) would have to stay closed or the K1 relay would not drop out when the gate switch was opened, and the K2 relay would not pick up to sound the danger horn. It is noted that the gate solenoid and the cave solenoid (see schematic) are activated by two independent radiation sensors, the Access Corridor detector, contact O1, and the in-cave monitor, contact OD. (In a letter dated December 30, 1997, the licensee informed the NRC that an in-cave monitor had been installed, tested and incorporated into the cave safety interlock system). Also, the gate solenoid and the cave solenoid are activated by contact KK1 when the key releases the source handling tool in preparation for the C0-60 source movements.
This arrangement meets the requirements of 10 CFR 20.1601 for control of access to high radiation areas. If one were to violate the procedures for gaining access to the Access Corridor, more than one failure would have to occur for one to gain access to the corridor with C0-60 sources in front of the Gamma Cave window, and not have the Danger Horn activated.
Additional features for preventing access to very high radiation areas, i.e., the Gamma Cave, as required by 10 CFR 20. 1602, are as follows. As mentioned previously, there is a double lock on the Gamma Cave door. Again, there would have to be another fai!ure of the electromechanical latch on the Gamma Cave door, i.e., cave solenoid, in addition to the failure of the latch on the Access Corridor door, in addition to the Danger horn not operating for one to get access to the Gamma Cave. In addition, in a letter from the licensee dated May 7, 1997, the licensee committed to placing a frisker-type Geiger-Mueller detector with a local alarm in the access corridor set a 10-20 mr/hr and positioned to respond to radiation from the cave door if it is opened. Thus it is seen that more than one failure would have to occur, in addition to a neglect of the procedures (Attachments 2 and 3) for one to get access to the Gamma Cave with the Cobalt-60 source in place. These additional features provide an adequate ..defense-in-depth" and meet the intent of 10 CFR 20.1602. Moreover, access to the containment is controlled, and the Access Corridor and Gamma Cave ere within the containment, and only approved or escorted individuals have access to containment.
Another requirement of 20.1601 (a) that can serve as an alternate to 20.1601 (a)(2) is in 20.1601(a)(3), which reads as follows.
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- entryways that are locked, except during periods when access to the areas is required, with positive control over each individual entry.*
As described previously, there are two barriers, each having two locks in place when movement of the Cobalt-60 sources is initiated. The procedures (see Attachment 2) require that the designated supervisor assure that these barriers are closed and lccked, and that all experimenters are aware of the Cobalt-60 movement. Therefore, although 20.1601 (a) requires only one of the three criteria in 20.1601(a) be satisfied, the configuration at UML satisfies both criteria in 20.1601 (a)(2) and (a)(3).
The only other requirement of 20.1601 that applies to UML is In 20.1601 (d) which reads as follows.
- The licensee shall establish the controls required by (a) of this section in a way that does not prevent individuals from leaving a high radiation area.*
The Gamma Cave facility is located within a controlled access reactor building. The Gamma Cave facility is normally closed and padlocked (keys controlled) when not in use, therefore access is restricted. There is an override switch located in the Access Corridor, which, if activated, releas'3S the electrical latch on the Access Corridor door and permits exit from the corridor.
The Gamma Cave door is padlocked. There are two physical features of the Gamma Cave that would preclude anyone from inadvertently being locked in. First a technician alone setting up an experiment can not physically shut the Gamma Cave door from the inside and padlock himself/herself in. Secondly, the dimensions of the Gamma Cave are about 8 ft. by 7 ft. by 8 ft.; it is virtually impossible not to see someone in a room of this size and inadvertently shut and padlock the door. Additionally, there is an in-cave alert switch in the Gamma Cave, which, if activated, energizes a flashing red light at the source control area and an audible Danger Horn, which can be heard throughout the containment building, that an unsafe condition exists.
Once an experiment is in progress, electromechanical interlocks prevent entry to the area until the source is removod, the source handling tool is returned to its storage location, and the radiation monitoring system is manually cleared from its alarm condition.
The staff agrees with the licensee that no credible scenario has been formulated where someone would inadvertently be padlocked in the Gamma Cave. The main intent of the in-cave alert switch was to provide immediate communication to the operation staff that a problem existed in the Gamma Cave or to release the electromechanical door interlock if it had been inadvertently triggered (the in-cave alert switch also releases the Gamma Cave electromechanical door interlock, see Attachment 4 schematic, K3b contact).
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3.0 ENVIRONMENTAL CONSIDERATION
This safety evaluation CSE) is not associated with I license amendment or a new application but a review of an existing system configuration. In the reference of Section 5.0 it is concluded in Sections 4.1 and 4.2 (enclosure 2) that the impact on public health and safety from radiation exposure due to operation of irradiators in the U.S. has been minimal and that worker exposure to radiation at irradiators are currently minimal.
4.0 CONCLUSION
The staff finds that the existing UML configuration for controlling access to high and very high radiation areas adequately addresses the requirements of 10 CFR 20.1601 and 20.1602.
5.0 REFERENCE
- orah Regulatory Analysis and Environmental Assessment of NRC Regulations on Licenses and Radiation Safety Requirements for Large Jrradiators,
- February 1989, page 3 (enclosure ), last sentence. Prepared for the Division of Regulatory Applications, Office of Nuclear Regulatory Research, U.S. Nuclear Regulatory Commission, by Science and Engineering Associates, Inc. and Mathtech, Inc. under Contract No. NRC-04-87-086.
Principal Contributor: Theodore S. Michaels Redacted for Public Release
Redacted for Public Release FNO.OSURE 1 irradiated arc underwater. Large panoramic irradiators include those in which the product being irradiated is in air in a radiation room that is nonnally accessible to personnel when the source is shielded. In all cases, the irradiators covered by the proposed rule have dose rates exceeding 500 rems per hour at a distance of one meter from the scaled sources either in air or water, depending on the type of irradiator. The rule docs not apply to self-contained irradiators (Category I),
agricultural irradiators, radiography cquipmcn or medical radiology and teletherapy equipment.
Only large irradiator licensees will be affecced. Other utilization facilities such as fuel fabricators, power reactors, and research and testing reactors will not be affected by the proposed rule.
This page is from the report entitled *oraft Regulatory Analysis and Environmental Assessment of NRC Regulations on Licenses and Radiation Safety Requirements for Large lrradiators: February 1989.
Report was prepared for the Division of Regulatory Applications, Office of Nuclear Regulatory Research, U.S. Nuclear Regulatory Commission. by Science and Engineering Associates Inc. and Mathtech, Inc. under Contract No. NRC-04-87-086.
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Redacted for Public Release ENCLOSURE 2
- 4. 0 CONSEQUENCES Since there are only two options to consider, one of which is the no action alternative (Option I),
it is only meaningful to discuss rhe incremental costs and benefits that would result from adopting the proposed rule (Option 2). In this section, incremental impacts are identified and discussed.
The current industry practices for irradiation facilities in the United States provide high safety standanls which have resulted in a history of relatively safe operations. For the most pan. the proposed rule simply codifies CWTCnt industty practices and in general causes little impact to the licensees, the public health and safety, or the NRC. However, several relatively small impacts have been identified and are discussed in the following subsections.
Before discussing impacts it is first necessary to note the type and number of licensees that will be affected. The proposed rule will apply to the 70 to 80 large irradiator facilities that arc currcndy in operation in the U.S. along with several proposed facilities and any future facilitier. that fall into the category of large imdiators. or rhe 70 to 80 operating facilities, 25 arc licensed by the NRC and 4S to SS arc licensed by Agreement States. It is expected that the Agreement States will follow the NRC lead by making compatible regulations. The consequences of the proposed rule are described below.
The data used to dctennine the consequences associated with the proposed rule were obtained primarily through a telephone survey of representatives from irradiator facilities and Agreement States. In addition, several existing licenses were reviewed to compare current practices and requirements with those of the proposed rule. The telephone survey covered state and NRC licensed large imdiators and included representatives from the Agreement States having the largest number of licensees. Other information was obtained by attending meetings with the NRC and rhe ANSI standards committee on the subject topic.
4.1 Public Health and Safety Radiation surveys at three irradiators indicated that radiation levels outside the facility could not be distinguished from natW'al background. Discussions with NRC inspcctOrs and other facility operators, indicated that the same situation would be encountered at other facilities. In addition, there are no rtl'Orted instances of public exposure to radiation from any U.S. irradiator.
Therefore, it is concluded that the impact on public he.alth and safety from radiation exposure due to the operation of irradiators in the U.S. has been minimal.
The existing license conditions for operation and the current NRC regulations have been determined to provide an acceptable level of protection for the health and safety of the public. The proposed rule perpetuates rhis level of protection, therefore, no incremental impacts arc associated with this action.
4.2 Qs:c:upatignal Radiation Exposure A review of recent personnel dosimetry processing repons at three iITadiators revealed no measurable radiation exposures of workers. Conversations with NRC inspectors and upcrators of other facilities, indicated that those results are what is found at other facilities as well. In addition.
there are no known cases of anyone entering a radiation room while sources were exposed since the current access control requirements were irnplememedby the NRC. Therefore, it is concluded that worker exposures to radiation at irradiators are currently minimal.
The requirements of the proposed ru:e will have no effect on routine occupational exposure which are governed by IOCFR Pan 20. Additionally, provisions of the proposed rule reduce the 9
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Redacted for Public Release ENCI.DSURE 2 probability of accidental exposures. This beneficial impact cannot be quantified since we cannot quantify the change in accident probability resulting from the new rule.
4.J lmlnalcx Costs agd Savina Results of the telephone survey and discussions with the ANSI standards committee indicate that compliance with the proposed rule will not impose a significant burden on the licensees and in some ways will benefit them. The creation of the new Part 36 will result in the following unquantifiable benefits or savings to the licensees:
- NRC review process should be more timely and streamlined
- license applications should be easier to prepare under a standarditt.d review process
- fewer iterations will be required to provide the necessary information In addition. the creation of Pan 36 will simplify irradiator operation by providing all necessary requirements in a single I OCFR reference.
In a telephone survey with representatives of licensed irradiators (both NRC and Agreement States) the requirements of the proposed rule were discussed. With only minor exceptions. the licensed facilities are in compliance with the safety criteria and requirements of the proposed rule. The exceptions to compliance with the proposed requirclll\!nts and their associated potential impacts are presented below:
- Access control system alanns must alert an individual attempting to enter the radiation room while the sources a.re exposed. In addition the alarms must alen at least one other person and that person must be prepared to render or summon assistance.
This requirement effectively specifics a two-person rule or a remote alarm system to alert an additional person. It was determined that most facilities have a two-person rule for operation of the irradiator or nonnally have additional people on-site that would hear and respond to an alarm. A few facilities were found that do not currently meet this requirement, buc to do so would only require a remote alarm system or a simple policy change to implement a two-person rule.
- The pool of an underwater irradiator must be within a restricted area and the area must be locked when not attended by and operator.
Results of this study found that only one facility currently did not meet this requirement. To do so would simply require the addition of a lock on an existing door.
- In terms of fire protection, radiation rooms for subject irradiators must be equipped with botll heat and smoke sensors to detect fires and a sprinkler system or ot'1er system to extinguish a fire without personnel entry into the room.
Results of the survey indicate that there are two currently operating facilities that do not have heat sensors. Of these two facilities. both have smoke detectors and one has a sprinkler system and one does n')t.
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Redacted for Public Release ATIACHMENT 1 DETAILED ANALYSIS OF CONFORMANCE TO PART 36 Section 36.23(a)
It must not be possible to move the sources out of their shielded position if the door or barrier is open.
The UMLRR operation is reversed since all source movement is manually accomplished.
However, it accomplishes the intent of the regulation - to assure that the source is not exposed when an individual is in its vicinity. UMLRR provides means to prevent entry to the radiation area and to assure that the source is not moved if access to the radiation area is available. Sources are in the form of stainless-steel-covered Cobalt-60 strips mounted in stainless steel racks. The racks are stored in specially designed crates. The sources at the UMLRR are stored at the bottom of the reactor pool. To use the sources(s) for irradiation levels in excess of 500 rads in the irradiation room hereafter called the Gamma Cave, a crate of Cobalt racks is placed on a work platform 10 feet under water and the rack(s) desired for the irradiation are manually moved from the work platform to the source holder mounted on the pool side of the Gamma Cave window the experiment to be irradiated is emplaced in the Gamma Cave. The sources remain in the pool at all times NormaJly both the entry barrier and Gamma Cave door are closed and locked with the key to the entry barrier kept in the control room. A green light at the pool level indicating this status is dearly visible from the control room and from the source handling tool area. Opening either or botn access barriers to the Gamma Cave causes the green light to shut off and a flashing yellow light to be lit. Therefore, there is dear indication at the pool level that shows that a barrier is open and the source should not be moved.
Openin& the door or barrier while the sources are exposed must cause the sources to return promptly to their shielded position.
Again, the UMLRR situation is the reverse of this. However, it accomplishes the intent of the regulation - to assure that the source is not exposed if an individual attempts to gain entry into the radiation area. The UMLRR operation both through procedures (see Attachment 2) and two separate controls assures that the access barriers can not be opened while the source is being moved or is in the irradiation position.
The source handling tool is interlocked with both access barriers. Unlocking the tool's permanently attached key results in electrically actuated piston locks on both access barriers, thereby denying entry to the area. Securing the source handling tool will not automatically release the locks if a radiation source has been used; the radiation monitoring system must be manually cleared from its alarm condition to release the locks. The radiation monitoring system can only be cleared if it no longer detects radiation greater than a value determined by the strength of the source(s) in use.
Additional detail describing a typical experimental set-up in the Gamma Cave is given in .
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- Note: The radiation monitoring system is checked on a nearly daily basis as part of reactor operation. Additionally, the system is designed as fail-safe; the loss of a component or module results in the system failing in the alarm mode.
The personnel entrance door or barrier must have a lock that is operated by the same key used to move the sources.
The intent of Part 36 is to have a key at the source control console which can not be removed from the console to gain access to the radiation areas while the source is exposed. The UMLRR operation does not include a source control console, however it accomplishes the intent of Part 36 because by procedure the door to the irradiation room is closed and padlocked after an experiment is set-up (see Attachment 4). As already described, prior to any source movement, two locked barriers are in place to prevent access to the Gamma Cave. Unlocking the source handling tool from its storage position activates additional electro-mechanical interlocks to these already mechanically locked barriers. Additionally the radiation monitoring system which is set to trigger when the system detects radiation in the Gamma Cave is electrically tied into the interlocked barriers. Two conditions must be met in order to clear the interlocks to the Gamma Cave and use the keys to gain access. The source handling tool must be returned to its storage location, the "No Movement" position, and the radiation monitoring system must be manually cleared from its alarm condition to release the interlocks. The UMLRR set-up assures that entry cannot be gained into the Gamma Cave while the source is exposed, thereby effectively accomplishing the one key requirement of the regulation.
The doors and barriers must not prevent any individual in the radiation room from leaving.
The Gamma Cave facility is located within a controlled access reactor building. The Gamma Cave facility itself is normally dosed and padlocked (keys controlled) when not in use, therefore acces,s is very restricted. There is an override switch located in the access corridor to unbolt and exit the entry barrier gate. However, the Gamma Cave door is padlocked. There are two physical features of the Gamma Cave that would preclude anyone from inadvertly being locked in. First a technician alone setting up an experiment can not physically shut the Gamma Cave door from the inside and padlock himself in. Secondly, the dimensions of the Gamma Cave are 8 feet by 8 feet by 8 feet; it is impossible not to see someone in a room of this size and inadvertently shut and padlock the door. Additionally, there is an in-cave alert switch in the Gamma Cave by which an individual can signal with a flashing red light at the source control area and an audible danger horn , which can be heard throughout the containment building that an unsafe condition exists.
Once an experiment is in progress, electromechanical interlocks prevent entry to the area until the source is removed, the source handling tool is returned to its storage location, and the radiation monitoring system is manually cleared from its alarm condition.
No credible scenario has been formulated where someone would inadvertly be padlocked in the Gamma Cave. The main intent of the in-cave alert switch was to provide immediate Redacted for Public Release
Redacted for Public Release communication t.o the operation staff that a problem existed in the Gamma Cave or to release the cove door interlock if it had been inadvertantly triggered..
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Redacted for Public Release Section 36.23(b)
Qetection of entry while the sources are exposed must cause the sources to return to their fully shielded position.
Since the sources are manually placed in a fixed position at UMLRR, this is not physically possible. However, UMLRR operation accomplishes the intent of the regulation by precluding entry into the radiation area. The UMLRR operation both through procedures (see Attachment
- 2) and two separate and independent barrier locks assure that the access barriers can not be opened while the source is being moved or is in the irradiation position.
The source handling tool is interlocked with both access barriers. Unlocking the tool's permanently attached key results in electrically actuated piston locks on both access barriers, thereby denying entry to the area. Securing the source handling tool will not by itself release the locks if a source had been placed in the radiation position; the radiation monitoring system also must be manually cleared from its alarm condition to release the locks. The radiation monitoring system alarm can only be cleared by operator action if it no longer detects radiation above a specific setpoint for the source(s) in use.
Section 36.23(d)
Before the sources move from their shielded position, the source control must automatically activate conspicuous visible and audible alarms. The alarms must give individual enough time to leave the room before the sources leave the shielded position.
Source movement is done manually. The source handling tool is locked with a restraint and key when sources are not in use. Unlocking the source handling tool under safe condions (all doors closed) causes a squee signal in the control room and a bell located within the access corridor area and audible throughout the containment building to sound for 3 seconds. The bell is a signal to the staff within containment that the sources will be moved.
If an unsafe condition existed (either access barrier doors open), a danger horn (not the bell) also located within the access corridor area and audible throughout the containment building would sound, as well as a flashing red light, visible from the source handling area and the control room. It should be noted that if either door had been open the operator would be aware of it prior to unlocking the source handling tool from the status of the lights at the source handling area (flashing yellow light lit, green light ofO. Procedures require a green light to be lit prior to unlocking the source handling tool and the bell to sound when the tool is unlocked Manually moving the source requires several minutes. Unlocking the source handling tool does not begin an automation process, but rather it affirms the staus of the Gamma Cave.
Again, a green light at the source handling tool area indicates a safe condition, unlocking the tool sounds the bell and squee affirming the safe condition. Unlocking the tool also actuates the door and barrier electromechanical interlock system, thereby preventing entry before the source is even moved.
Redacted for Public Release
Redacted for Public Release Section 36.23(e)
Each radiation room of a panoramic irradiator mut have a clearly visible and readily accessible contol that would allow an individual in the room to make the sources return to their fully shielded position .
Again, the UMLRR situation is the reverse of this. However, it accomplishes the intent of the regulation - to assure that the source is not exposed if an individual attempts to gain entry into the radiation area. The UMLRR operation both through procedures and two separate and independent controls assures that the access barriers can not be opened while the source is being moved or is in the irradiation position.
The source handling tool is interlocked with both access barriers. Unlocking the tool's permanently attached key results in electrically actuated piston locks on both access barriers, thereby denying entry to the area. Securing the source handling tool will not automatically release the locks; the radiation monitoring system must be manually cleared from its alarm condition to release the locks. The radiation monitoring system can only be cleared if it no longer detects radiation.
Section 36.23(0 Each radiation room of a panoramic irradiator must contain a control that prevents the sources from moving from the shielded position unless the control has been activated and the door of barrier to the irradiation room has been dosed within a preset time after activation of the control.
Again, the UMLRR situation is the reverse of this. However, it accomplishes the intent of the regulation - to assure that the source is not exposed if an individual attempts to gain entry into the radiation area. The UMLRR operation both through procedures and two separate and independent controls assures that the access barriers can not be opened while the source is being moved or is in the irradiation position.
The source handling tool is interlocked with both access barriers. Unlocking the tool's permanently attached key results in electrically actuated piston locks on both access barriers, thereby denying entry to the area. Securing the source handling tool will not automatically release the locks; the radiation monitoring system must be manually cleared from its alarm condition to release the locks. The radiation monitoring system can only be cleared if it no longer detects radiation.
Section 36.27(a)
The radiation room of a panoramic irradiator must have heat and smoke detectors. The detectors must activate an audible alarm. The alarm must be capable of alerting a person who is prt:pared to summon assistance promptly. The sources must automatically become fully shielded if a fire is detected.
The radiation room is a steel and concrete vault. The only combustible material present is that being irradiated. The sources which are configured in a planar array are located in a water pool adjacent to the radiation room. Therefore an experiment in the Gamma Cave is only irradiated from one side. The source and radiation room design is only adequate for small Redacted for Public Release
Redacted for Public Release experiments requiring a precise dose. The facility is not designed for bulk irradiation because of limited space and poor source to sample geometry. Facility Technical Specifications and Standing Orders prohibit explosives and most flammable materials from the reactor building.
In response to specific comments a)The radioactive sources are outside the exposure room in an adjacent water pool. There is no possible mechanism for the release of radioactive material since there is no radioactivity in the exposure room.
b) Any materials with the potential to affect the pool liner, i.e. explosives, are already prohibited from the containment building.
c) The Gamma Cave itself is a vault. The only combustible material present is that being irradiated and a ventilation filter. Given the source to room design, most samples are of small size.
d) Any material that did ignite in the Gamma Cave would be left to burn itself out (see Attachment 5). Smoke would be removed by the exhaust fan located in the room. Since the sources are in the water pool adjacent to the Gamma Cave, their physical condition and movement would not be affected by a fire.
e) Over the 13 years of Gamma Cave operation there has never been a spontaneous corrbustion. The installation of expensive and sensitive equipment such as fire and smoke detection in an intense radiation field would be of marginal benefit to the facility since intervention to fight fire would not be considered a logical course of action.
Section 36.27(b)
The radiation room of a panoramic irradiator must be equipped wilth a fire extinguishing ststem capable of extinguishing a fire without entry of personnel into the room.
See the discussion above.
Section 36.31 (a)
The mechanism that moves the sources must require a key to actuate. Actuation of the mechanism must cause an audible signal to indicate that sources are leaving the shielded position. Only one key may may be in use at any time and only operators or facility management may possess it.
There is only one key permanently attached to the source handling tool that must be unlocked in order to move the source. This is the only key in use at any time that allows movement of the source. Unlocking the source handling tool under safe conditions (all doors closed) causes a squee signal in the control room and a bell located within the access.corridor area and audible throughout the containment building to sound for 3 seconds. The bell is a signal to the staff within containment that the source will be moved.
Additional keys are needed to gain entry into the Gamma Cave. One key for the entry barrier and a different one for the Gamma Cave padlock are needed. Again, because of the interlock system these two keys will only release the barriers if two conditions are met; namely, Redacted for Public Release
Redacted for Public Release the source handling tool must be locked in its storage position and the radiation monitoring system must be manually cleared from its alarm condition. The entry barrier key, along with all facility keys are kept in a storage box in the control room. Keys are only accessible to reactor personnel in a controlled access area.
The key must be attached to a portable radiation survey meter by a chain or cable. The lock for source control must be designed so that the key may not be removed if the so urces are in an unshielded position. The door to the radiation room must require the same key.
The justification for different keys is listed under section 36.23(a)3. However, the key to the padlock on the Gamma Cave door is permanently attached to a survey meter by a cable. The meter is kept on a storage shelf within the locked access corridor.
Section 36.Jt(b)
The console of a panoramic irradiato r must have a sour ,tiosition indicator that indicates when the sources are in the fully shielded position, when they are in transit, and when the sources are exposed.
There is no control console, since movement is done manually. However the intent of the regulation - assure personnel know the status of the source(s) is met by the illumination of different lights. A staff member prior to using the entry barrier key, is aware of the status of the source from the radiation monitor meter and status lights located in the access corridor. One indicator (meter reads in mr /hr), marked as "CAVE DOOR LEVEL", has a green and red light.
The red light indicates one of two things: the radiation monitor is detecting radiation in the Gamma Cave (the field can be determined by reading the meter), or that the Q radiation monitoring channel in the control room has not been manually cleared. Regardless of the source of the red light, the interlock to both access barriers is activated and access is precluded.
Section 36.31(c)
The console of a panoramic irradiator must have a control that promptly returns the sources to the shielded position.
Again, this is not possible since there is no control console and the source is moved manually. St.e Section 36.23(a)2 above.
Section 36.31(d)
Each console for a panoramic irradiator must be dearly marked as to its function.
Again, this is not possible since there is no control console and the source is moved manually.
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Redacted for Public Release A'ITACHMENT 2 GAMMA CA VE OPERATIONS Redacted for Public Release
Redacted for Public Release REV. 2, 24 Mar. 97 STANDING ORDER #10 GAMMA CAVE OPERATION AND AIARM SETPOINTS 1.0. SETIING UP IRRADIATION 1.1 Obtain key to gamma cave entry banier from control room (3rd floor).
1.2 Assure that the source handling tool is secured by its key Jock and the wall mounted interlock light is green (3rd floor).
1.3 Prior to opening entry banier, assure that all indications on the radiation monitor in the access corridor are green (1st floor).
1.4 Unlock entry banier, pick up radiation survey meter With attached gamma cave padlock key from storage shelf. Make sure the survey meter is operational by perlorming battery and operational checks. Survey area. If exposure levels exceed 1.0 mR/hr CAetermine source of exposure before proceeding. Unlock and open gamma cave door.
1.5 Set up experiment in gamma cave.
1.6 Oear gamma cave, assure all personnel are out, close and padlock gamma cave door. Return survey meter With attached key to storage shelf.
1.7 Oear access conidor, close entry banier; assure that all barriers are properly closed as indicated by a yellow light on the radiation monitor in the access corridor.
1.8 Prior to unlocking the source handling tool key, assure that the wan mounted interlock light is green (3rd floor) 1.9 Unlock the source handling tool, note that the warning bell sounds, pick appropriate cobalt source(s) from storage rack, and place source on window of gamma cave. Assure that the radiation monitor channel Q in the control room has alarmed high. Adjust setpoint if necessary per Section 3.0 2.0. SECURING IRRADIATION 2.1 Upon completion of irradiation, remove cobalt from gamma cave Window and return source(s) to storage rack 2.2 Return source handling tool to its storage location and relock the key. In the control room, clear channel Q on the radiation monitor from its alarm condition, and obtain key to the entry barrier.
2.3 Follow steps 1 3, and 1.4.
2.4 Retrieve experiment from gamma cave, follow steps 1.6 and 1.7.
2.5 Return entry banier key to control room.
3.0 ADJUSTING ALAR\1 SEJPOINT The decay of the cobalt -60 source necessitates the constant review of the alann setpoints used in the Gamma Cave Interlock System. Because of this review RF-4, in regard to Channel Q, reads "c;et alarm points as per current standing order.
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Redacted for Public Release REV. 24 Mar. 97 I.Dw Level Trip Value, mR/hr = 0.3 Htgh Level Trip Value, mR/ hr = 0.5 If the rack used is not of sufficient strength to reach these levels (i.e. Rack #158) the High Level Trip Value should be lowered so as to engage the interlock. This setpotnt should be returned to its normal value prior to disengaging the interlock system.
Approved by:
fif- :.Ji: d#::.-
Bettenhausen, Reactor Supervisor
-7 Redacted for Public Release
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Redacted for Public Release R0-16 REV 3 17 MAY 89 BQ-16 MOVEMENT QF C0-60 SOURCE IN THE REACTOR POOL I. A Senior Operator or an individual designated by the Reactor Supervisor will supervise all movement of the cobajt source. The designated supervisor shall apprise the control room operator of all anticipated Co-60 movements.
- 2. Under no circumstances will any portion of the Co-60 source be moved into the reactor end of the pool while the reactor is in operation.
- 3. Whenever possible, the Co-60 strips will only be moved while they are housed in the appropriate frames. Individual strips shall not be moved or handled while the reactor primary coolant system is in operation.
- 4. Frames will not be handled when the Primary Coolant Sytem is in operation without the approval of the reactor SRO (as designated in reactor operating log).
- 5. All handling of the source will be performed at least 8 feel below the surface unless a dedicated radiation monitor is present.
- 6. Before the designated supervisor all 0ws any cobalt-60 movement, he/she will personnally assure the following:
A. The Gamma Cave door is clo£cd and locked.
B. The Gamma Cave gate is closed and locked.
C All experimenters are aware of Co-t)O movement.
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Redacted for Public Release S.P. I A SYSTEM TEST FOR THE GAMMA CAYE INTERLOCK S:XSTEM 1.0 PurpQse I .I The interlock system for the Gamma Cave is designed to prevent inadvertant radiation exposure, or any other unsafe condition with the Gamma Cave system.
This test will demonsuate that all conditions of the Gamma Cave system will indicate the appropriate warning.
2.0 Equipment Required 2.1 Small gamma source.
3.0 References
- 3. i Gamma cave interlock system schematic 4.0 Procedure 4.1 Follow the outline given on reactor form RF-Sf' I A.I (Sysytem Test for the Gamma Cave Interlock System).
4.2 End.
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Redacted for Public Release RF-SPIA. l System Test for the Gamma C;ve Interlock System I. Verify that the facility 1s m the following initial conditions:
A) Gate Door Shut B) Cave Door Shut C) Gamma Radiation Monitor Module With No Alarm D) Tool Key In Storage Position
Green Light On
- 2. Open the outer gate and verify the following:
____ Green Light Off
____ Yellow Light Blinking On
- 3. Shut Gate Door and verify the following:
____ Green Light On, Yellow light stops blinking Note: Ensure Proper Radiological Precautions Are Taken For Step 4
- 4. Open Cave Door and verify the following:
______ Green Light Off Yellow Light Blinking On
- 5. Enter Gamma Cave and Shut Gamma Cave Door. Turn Tool Key To Move Pole, then verify the following:
Bell Sounds for Approximately 3 Seconds Cave and Gate Interlocks Energize
- 6. Operate Test Switch Inside Gamma Cave and verify
_______ Danger Horn Sounds
Cave Interlock Piston Clears
- 7. Open Cave Door, Then Operate Test Switch Inside Gate Area on side of horn and verify
Danger Horn Sounds
- 8. Shut Cave Door (stay in gate area) and verify
____ ___ Green Light On
- 9. Turn Tool Key To Move Pole, then verify the following:
Squee Sounds for Approximately 3 Seconds
Cave and Gate Interlocks Energize
- 10. Push Gate Overide Button, and verify Gate Interlock Clears R.F.-S.P. IA. l Page l Redacted for Public Release
- Redacted for Public Release
- 11. Open Gate Door, and verify Danger Horn Sounds Yellow Light Blinks On Red Light Blinks On
- 12. Shut Gate Door and return key to storage position, then verify
Green Light On
- 13. Energize Gamma Module High Alarm, then verify the following:
____ Bell and Squee Sounds for Approximately 3 Seconds
____ Cave Interlock Energizes
____ Gate Interlock Energizes
- 14. Clear Gamma Module High Alarm, open gate door and then turn key to move pole. Then verify the following:
Danger Horn Sounds Yellow Light Remains Blinking Red Light Blinks On
- 15. Turn Key to Storage Position, then open cave door, and shut the gate door, then verify the Yellow Light Blinking On Turn key to move pole.Then verify the following:
Danger Horn Sounds
_______ Yellow Light Remains Blinking
Red Light Blinks On Technican________________ Review (CRO)
R.F.-S.P. I A. I Page I Redacted for Public Release
Redacted for Public Release AITACHMENT 3 DESCRIPTION OF GAMMA CAVE EXPERIMENTAL SE11JP Redacted for Public Release
Gamma Cave Eforxpe Redacted Public ental Set Up rimRelease Two staff members are primarily responsible for the operation of the Gamma Cave facility.
However, the Gamma Cave is an integral part of the reactor's experimental facilities; therefore all licensed operators are familiar with all aspects of the Gamma Cave operations. The following is a summary of an experimental set up in the Gamma Cave and the series of events and interlocks that are activated.
A sample for gamma irradiation is given to a staff member /reactor operator. The operator calculates the distance from the source the sample needs to be placed in order to obtain the requested total dose. He obtains the entry barrier key from the key box in the control room. -:hecks that the source handling tool is in the storage location and a green light is indicated on the wall mounted interlock lights (figure I). He proceeds to the 1st floor (figure 2). Prior to opening the entry barrier he checks the gamma cell monitor panel (figure 3) in the access corridor. He sees two green lights: one is marked "IN CAVE ALERT", the other is marked "CAVE DOOR LEVEL". If either of these lights had been red, the interlock would have been activated and the electromechanical lock would preclude entry.
When he opens the entry barrier, the yellow door closed light on the Gamma Cell Monitor Panel goes off and the red door open light is lit. At the same time on the 3rd floor, the wall mounted signal green light goes off and a flashing yellow light is lit. This signals to facility staff on the 3rd floor that one or both access barriers to the Gamma Cave are open. The operator picks up the survey meter with its attached key from th storage shelf, surveys the area, and uses the attached key to unlock the Gamma Cave door padlock. He enters the Gamma Cave with the survey meter, places the sample at the appropriate distance and shuts and padlocks the door. He replaces the survey meter and shuts the entry barrier. Before walking away, he checks that the door status light on the gamma cell monitor panel indicates both doors are properly closed.
On the 3rd floor, he requests help from a staff member to assist and observe him move the source and .... tart a stopwatch to time the irradiation. Prior to unlocking the source handling tool, he looks up at thl' signal lights to make sure that the green light is lit and the flashing yellow light is off.
Unlocking the source handling tool, a bell sounds for 3 seconds, indicating that he can proceed. It takes approximately 5 minutes to move the source handling tool to the storage basket in the pool, pick the appropriate source frame of Co-60 and then manually walk it to the fixed position of the Gamma Cave window. Once the source is positioned on the window, he walks over to the control room, returns the entry barrier key, and assures that channel Q on the radiation monitor panel is tripped high (illuminates a red light). If the high trip has not occurred, the red monitor setpoint is lowered to lock in a trip condition.
When the timed irradiation is completed, he removes the source from the window to the storage basket and replaces the source handling tool at its storage location. He locks the key attached to source handling tool. At this point, the interlock system is till actuated. When he obtains he key for the entry barrier from the control room, he manually clears the ahrm trip on the Q channel of radiation monitor. The two condition:; to deactivate the interlock system have now been met. He proceeds to the 1st fl<xJr and repeats the steps described above to gain entry to the Gamma Cave and retrieve the irradiated experiment.
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Redacted for Public Release Flt(IRF .1 Redacted for Public Release
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.f/tll8E 2 Redacted for Public Release
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Redacted for Public Release ATTACHMENT 4 GAMMA CAVE INTERLOCK SYSTEM Redacted for Public Release
Redacted for Public Release DESCRIPTION OF TiiE GAMMA CAVE INTERLOCK SYSTEM The gamma cave area consists of an inner cave and cave access corridor. The purpose of the Interlock System is to prevent an unsafe condition in either area. Cobalt-60 (Co-60) may only be moved from the shelf to the gamma cave window when both the cave door and entry barrier gate are closed. If Co-60 is on the window and either door is accessed, an audible and visible alarm will energiz.e. If either door is open when a Co-60 move is attempted, the alarm will energize.
The primary indication of the status of the interlock system is a group of three lights at the pool level. The lights are green, yellow and red. When the green light is on, Co-60 can be moved safely; this means the cave door and entry barrier gate are both closed.
When both door and gate are shut, the gate switch and cave switch will close, which will energiz.e relay Kl. Contacts KIA and KlB will open, and contact KlC will close. Contact KlC will energize relay KG. Contact KG will close which will then energize the green light at the pool level.
When one of the doors are open, relay Kl will de-energize. Contacts KlA and KlB will close and contact KlC will open. Contact KlB will then allow relay KY to energize; this will shut contact KY, then the yellow light will blink on or off.
The pole which is used to move Co-60 from the shelf to the gamma cave window has a key attached to it by a short steel cable. This key fits into a key box on the pool wall by the pole storage position. When the pole is stored the key is inserted into the box and turned to tJ1P "stored" position.
The pole can not be used to move Co-60 without removing the key from the bv.... fhe key can only be removed from th'? box by turning it to the proper position.
With a green light the Co-60 is allowed to be moved. The key will be turned which will de energize relay I<K. This will cause contact I<Kl and KK3 to close and contact I<I<2 to open. Contact KKl will energize the cave door solenoid operated air valve and will also energize the transformer for the gate solenoid which will cause the solenoid for the gate to energize. These solenoids are the physical interlocks for the two doors to prevent opening while Co-60 is being moved or is on the window. Contacts Qt and QD will cause the same effect as contact KKI. Ql is closed when the radiation monitor in the access corridor is tripped. QD is tripped by an in-cave monitor.
If either door or gate is open or opened while contacts Ql, QD, or KKl are shut, which would indicate Co-60 is on the window or the pole is out of the storage position, relay Kl will de-energize.
When relay Kl de-energizes, contact KIA will close causing relay I<2 to energize. When relay K2 energizes, contacts K2A Jnd K2B will dose. Contact 1<2A closing will supply power to the Danger Horn. Contact K2B dosing will energize relay KR. This will cause contact KR to close which will energize the red light at the pool level. The red light will blink on and off.
If the alert switch in the cave is thrown on, K3 will be energized, dosing contact I<3A with a resulting Danger Hom and opening K3B which deenergizes the cave door soleniod air valve in event of inadvertant operation.
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Redacted for Public Release
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Redacted for Public Release ATTACHMENT 5 FIRE HAZARD ANALYSIS Redacted for Public Release
- Redacted for Public Release flRE HAZARD ANALYSIS GAMMA CAVE Consider that, despite prohibitions against flammable materials in the reactor facility, and the insult to personal safety by placing a volatile fluid in a small enclosed volume, and no prior history of irradiating flammables, and no ignition source in the 8' cube Gamma Cave, some experimenter places a sizable sample of a flammable liquid such as xylene, methyl alcohol, or ethylene on the experimental shelf and by some means it ignites during the course of an irradiation when the cave is dosed, locked, and interlocked. The quantity of flammable liquid will be limited by the practical considerations of experiment size. The limitation of the amount of oxygen present in the dosed Gamma Cave with only air seepage around the door and the few unsealed instrument penetrations will limit combustion.
The amount of oxygen present in the 8 ft cube will support combustion of 1.4 kg of ethylene I, for example. So let us consider a typical 3 liter container of flammable liquid with dimensions 20 cm high by 15 cm diameter placed 30 cm from the window on the shelf of the Gamma Cave.
Since the combustion would occur at the liquid-air interface, the burning rate can be estimated as 0.2-0.3 cm/min 2 and of the radiant energy released by the fire, 2 kcal/cm 2 .min is radiated from the flame. The surface area of the container is 175 cm 2, so the radiant energy is 350 kcal/n1in. Assume a plane flame confined in the shelf area; then half (or less) of the radiated energy is directed at the 2 foot square, thick Al window or Q=175 kcal/min = 44 Btu/min= 2646 Btu/hr Since the window is thin relative to area and highly conducting, ignore temperature differences across it. On the other side is a 75,000 gal pool of water at a nominal 70F and 26' water head (Tsat= 236F). A heat transfer coefficient for vertical convection is given .ias h = b (DT)ffi t3m-1 in BTU/hr ft2 F Since bis 26, m is 1 /4 and L is the characteristic length of the heat transfer surface, 2 ft, a temperature difference of 15F is sufficient tc remove the radiant heat load by natural convection of the water on the plate. The air in the Gamma Cave would also heat up and provide an additional heat source. This would act in a longer time but be greater in overall magnitude than the radiant component (5.1 kcal/cm 2 *min vs 2 I Marks, MchanicaJ Enainccrs' Handbook, kGraw-Hill, 1958, p.472 2 "Radiation from Pool flames", Heat Transfer in flames. Scripta, Washington DC, 974, pp. 413 ff.
3 Perry, Cbcmjcal Enaiocers' Handbook, Section 10.
Redacted for Public Release
- Redacted for Public Release kcal/an 2 min). Ta.king the mass of air in the cave and ignoring formation of H2<) and CO2, delta Q = 89250 kcal and cv = 0.3039 kcal/gm C with 14.7 kg air in the cave, the final air temperature rise in the cave is 15 C or 28 F.
For conservatism, take a heat flux comparable to the radiant flux directed to the aluminum plate "window". Then Qin= 5292 Btu/hr and delta T = (60.s,S/4 = 27 F, The tmperature is still well below the ONB, so convective cooling is sufficient to cool the plate.
If the situation got to the boiling point, the ONB heat transfer coefficient for the UMLRR4is h = 250 Btu/hr ft2 F; thus delta T at boiling would only be 2.65 F so heat removal by boiling onset would occur at the pool-window and, since the fluid to-vapor enthalpy change of water under these conditions is 970 Btu/lb, only a few pounds of water would boil to keep the plate temperature well below 300 F.
As a second check, use the correlation described in Glasstone and Sesonske S, For free convection with a vertical surface, obtain the Grasshof and Prandtl numbers for the watr conditions of 80F nd a 2 ft square plate to be:
Gr= 27.76E9 and Pr= 4.403 and use in the correlation Nu = 0.SS(Gr Pr)0.25=
325.2 and since Nu= hx/k, h = 61.3 BTIJ/hr ft 2 F, a slightly larger value than that used earlier Thus, for a fire involving the amount of a volatile fuel of the quantity which would consume all ofthe oxygen in the Gamma Cave if quickly combusted, the rate of burning dictated by physics of combustion results in a temperature rise in the aluminum pool hner window of 15-30 F, since the pool side of the window is immersed in a 75,000 gal water pool. The stainless-steel encapsulated sources are separated from the window by a 3/4" water space and would be heated a few degrees only by the convective water movement about them. A fire in the Gamma Cave has little impact on the cave itself since it is a concrete and steel structJ1e and only a small effect on the CobaJt-60 sources immersed in the 75,000 gallon pool of water and separated from the fire by a thick aluminum plate..
.J Updated Hnal Safely Anal1 sis Report for University of Lowell Rcanor, 198S. Section <)
5 Nuclear Reactor Enainecdo&, Glasstonc and Scsonskc, Van Nostrand, I 962, pp 378-379 Redacted for Public Release
Redacted for Public Release ATTACHMENT 6
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