ML19256A205
| ML19256A205 | |
| Person / Time | |
|---|---|
| Site: | 05000113 |
| Issue date: | 10/12/1978 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML19256A199 | List: |
| References | |
| NUDOCS 7811030232 | |
| Download: ML19256A205 (6) | |
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UNIT E D STATES e'
NUCLEAR REGULATORY COMMISSION W ASHINGToN, D. C. 20555 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION S_UPPORTING AMENDMENT NO.13 TO FACILITY LICENSE N0. R-52 THE UNIVERSITY OF ARIZONA DOCKET NO. 50-113 Introduction By letter of July 14, 1977, the University of Arizona (the licensee) requested an amendment to Facility License No. R-52 which includes changes to the Technical Specifications for their TRIGA reactor. We have evaluated these changes as discussed below.
Discussion 1.
Ed_itorial and Administrative Changes The licensee has proposed various editorial changes to incorporate currently used terminology and to effect changes in the onsite organization and position titles. These changes would be as follows:
a.
Replace the words " Abnormal Occurrence" with " Reportable Occurrence".
b.
Change AEC to NRC and up ate address for reporting requirements.
c.
Delete the words "where appropriate" from the requirement to make a submittal of a Reportable Occurrence.
d.
Change the licensee's organization to establish a new position of Reactor Supervisor having responsibilities for approving routine irradiations for the Reactor Committee and scheduling reactor experiments. These duties have been the responsibility of the Reactor Laboratory Director.
e.
Update the organization chart to reflect title changes consisting of changing Reactor Laboratory Director _to Reactor Laboratory Head, Physical Resources Director to Director of Radiation
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Safety and Hazards Control Office to Radiation Safety Office.
Insert Reactor Supervisor in the organization below Nuclear Reactor Laboratory Hebd.
7611030$
. 2.
Increase in Maximum Authorized Pulse Input The licensee has requested an increase of the maximum insertion reactivity during the pulse mode from $2.10 to $2.501l The reactor is designed to accept a maximum insertion reactivity of $3.00.
3.
Instrumentation Operability Requiremen_ts The licensee has proposed to modify the surveillance requirements for the reactor tank water temperature channel by deleting the requirement that it be channel tested.
However, these channels are to be tested for operability before the reactor is operated.
The reactor tank water temperature is also listed under the reactor instrumentation section of the technical specification which must be. checked for operability before the reactor is operated.
Delete the requirement to check-out the pulse mode instrumentation when the reactor is operated in a steady state mode.
Evaluation 1.
Editorial and Administrative Changes The purpose of these changes is to have the terminology in the specifications agree with that normally used by the University Staff. Therefore, these changes are editorial in nature and do not relax or change the safety requirements of the specifications.
The proposed updating of the organization chart reflects a change in University nonenclature for the Reactor Laboratory Director to the Reactor Laboratory Head and a change in the administration of the Health Physics efforts. The Director of Radiation Safety is a new position, but there have not been personnel changes in the Radiation Safety Office.
In the past the responsibility of the Hazards Control Office covered all potential hazards at the University including radiation safety of the reactor. The facility radiation safety responsiblity of the former Hazards Control Office are now assigned to the new Radiation Safety Office which will have the radiation safety responsibility for the reactor and all irradiation experiments. This change will in no way reduce or change the level of safety of reactor operation from the standpoint of radiation protection because there has not been a decrease in the reporting level of the radiation safety office. Therefore, no change occurred in the independency between the Radiation Safety Office and reactor operations.
E e dollar and cents expression is a standard measure of reactivity Th f r rocctors.
. Initally, the University of Arizona had one person serving as both Reactor Laboratory Director and Reactor Supervisor. These two titles became interchanged and confusing at times because of the duality of responsibilities by a single person. The current Technical Specification requires that an applicant for routine materials irradiation submit his request to the Reactor Supervisor and the approval would be by the Reactor Laboratory Director. The licensee informed the staff that it'was originally intended that the Reactor Supervisor rather than the Reactor Laboratory Director approve such routine irradiation experiments.
Since the Reactor Supervisor position has been filled by a qualified person meeting the requirements of Senior Reactor Operator, the staff finds this change acceptable.
2.
Increase in Maximum Authorized Pulse Input The licensee is authorized to operate the facility at a maximum reactivity insertion of $2.10 in the pulse mode.
In order to improve the effectiveness of the reactor as a teaching tool, by allowing data to be collected over a wider range of input reactivities, the licensee has proposed to increase the maximum allowable reactivity to $2.50. The standard TRIGA fuel elements specified for this reactor have a long history of successful pulse operation at this reactivity insertion level and are designed for a maximum pulse level of $3.00 corresponding to a fuel element tem-perature of 750 C.
Many TRIGA reactors with a similar core geometry and fuel elements are licensed for reactivity inputs in the pulse mode of $3.00. The Safety Analysis Report (SAR) shows the measured maximum fuel temperature during a $2.50 input reactivity is 500 C, which is well below the fuel safety criterion temperature of 1000 C and below the 750 C for a reactivity insertion limit of $3.00. The design safety margin is not reduced when the input reactivity in the pulse mode is raised from $2.10 to $2.50.
This is because the operating conditions are below the design parameters of 750 C which in itself contain an adequate design safety margin for both the fuel element and the reactor core.
Therefore design safety margin will be reduced only when fuel element temperature rises above 750 C which will not occur during an input reactivity of $2.50.
Tabulated below is the change in insertion reactivity as it affects fuel element temperature, a limiting parameter for safe operation:
Center line fuel oK/K temperature in dollar Pulse Mode C RemarPs_
2.10 367 Permitted by present Technical Specifications 2.50 500 Proposed by this amendment 3.00 750 Other TRIGA reactors are permitted to operate at this level reactivity design limit
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> 3. 00 1000 Safety criterion temperature limit Furthermore, the safety criterion temperature limit (1000 F), a design parameter for TRIGA fuel elements, has an additional safety margin because the fuel elements with hydrogen to zirconium ratios of at least 1.65 have pulsed to temperatures of about 1150 C without damage to the clad.
Therefore the 1150 C is considered known upper bound in the safety margin.
Pulse limitations are based on fuel element temperature and reactivity insertion, thus changing these limits does not constitute a change in the authorized power level of 100KW.
Furthermore, operating experi-ence has demonstrated that the clad of the fuel elements which prevents fission product escape have not failed under reactivity insertions of $3.00.
This value is $.50 higher than that being re-quested in this amendment.
Based on this experience the clad is not expected to fail under the proposed pulse mode operating con-ditions.
Consequently, the staff has concluded that the types and the amounts of effluents to the environment is unchanged.
3.
Instrumenta_ tion Operabil_it_y Requirements The licensee has requested deletion of the reactor tank water temperature from the list of channels in the Technical Specifica-tions that requires testing by introducing a test signal to verify operabil ity.
Thus, introducing a test signal to verify the opera-bility of a channel is the definition of a channel test given in the Technical Specifications.
In support of his request, the licensee states that this channel does not activate the automatic scram circuitry and should not be considered part of the reactor safety system channels.
The reason is that the temperature of the reactor tank water rises to a maximum rate of 5 C per hour at full power of 100KW.
It would take about 17 hours1.967593e-4 days <br />0.00472 hours <br />2.810847e-5 weeks <br />6.4685e-6 months <br /> for the temperature to increase from to boiling, and yet many days before ambient temperature (15 C)d significantly to warrant concern by the water level is lowere boiling. Such an elapsed time is more than cdequate for an operator to take corrective action before conditions become hazardous. Also, for this reason an increase in coolant temperature was not considered as a safety hazard in the SAR. The reactor tank water temperature however, is information needed by the reactor operator to properly operate the reactor and it is displayed in the control rooms. To assure the accuracy of this information, the specification requires the reactor tank water temperature to be checked for operability before the reactor is operated. This temperature measuring channel is designed for a channel check but not a channel test (as defined above).
Presently this temperature channel is tested by introducing a test signal from an outside circuit not built into the channel.
Normally those channels designed for a channel test have a built-in circuitry to introduce a test signal. A channel check verifies the information from the channel by comparing it with other in-dependent channels or methods measuring the same variable.
For these reasons, we agree that the reactor tank water temperature channel test is not necessary and the margin of safety will not be reduced by removing this channel from the channel test list.
. The licensee has requested the instrument and safety channels used only in the pulse mode be checked when the pulse mode operation is scheduled and not for the normal steady state operating mode as they are now required. Some of these channels required only in the pulse mode are the high range power level, the 10 KW' interlocks, and the peak power scram. However, electronics that are required for both modes of operation, includino the transient rod interlock that prevents pulse mode operation with the mode selector switch in the manual position, will continue to be checked for normal steady state operation. The pulse mode operation is seldom used (i.e., about 5% of reactor runs during 1975 and 1976). The 'icensee conducts many reactor startups during the year and is required by the specifications to make instrument and safety channel checks before each startup. The specifications, however, should not require the instrument and safety channel checks to those channels which are not needed for safe plant operation nor required for operator information to properly operate the reactor.
We have concluded that the above changes do not reduce the level of safety of the facility and do more clearly define the requirements in the Technical Specifications. Also, these changes do not compromise the requirements of the Technical Specifications but do bring the Technical Specifications more into line with the actual state of the art capabilities and the existing conditions at the facility. Therefore, the proposed changes are acceptable and do not reduce any of the safety margins.
Environmental Consideration We have determined that the amendment does not authorize a change in effluent types or total amounts nor an increase in power level and will not result in any significant environmental impact. Having made this determination, we have further concluded that the amendment involves an action which is insignificant from the standpoint of environmental impact and, pursuant to 10 CFR Section 51.5(d)(4), that an enviror, mental impact statement or negative declaration and environmental impact appraisal need not be prepared in connection with the issuance of this amendment.
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. Conclusion We have concluded, based on the considerations discussed above, that:
(1) because the amendment does not involve a significant increase in the probability or consequences of accidents previously considered and does not involve a significant decrease in a safety margin, the amendment does not involve a significant hazards consideration, (2) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, and (3) such activities will be conducted in compliance with the Commission's regulations and the issuance of this amendment will not be inimical to the common defense and security or to the health and safety of the public.
Dated: October 12, 1978 e
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