ML20036A777
| ML20036A777 | |
| Person / Time | |
|---|---|
| Site: | Zion File:ZionSolutions icon.png |
| Issue date: | 05/04/1993 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20036A774 | List: |
| References | |
| NUDOCS 9305140189 | |
| Download: ML20036A777 (4) | |
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UNITED STATES
[ khi j NUCLEAR REGULATORY COMMISSION g*g WASHINGTON, D.C. 20555 0001 g '.v f
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T SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACT 0't REGULATION RELATED TO AMENDMENT NO.145 TO FAClllTY OPERATING LICENSE NO. DPR-39 COMMONWEALTH EDISON COMPANY ZION NUCLEAR POWER STATION. UNIT 1 DOCKET NO. 50-295 l
1.0 INTRODUCTION
In a letter dated March 3, 1993, Commonwealth Edison Company (CECO, the licensee) requested a change to Accident Monitoring Instrumentation Tables 3.8.9-1 and 4.8.9-1 of the Technical Specifications (TS) for a one-time i
extension of the channel calibration of the Unit I containment recirculation i
sump level instrumentation (CRSLI) until the end of the next refueling outage currently scheduled for October 22, 1993, and the deletion of footnotes that are no longer applicable.
If Unit I experiences a forced outage requiring a shutdown to Mode 3 or below prior to the next scheduled refueling outage, the licensee has committed to calibrate the instrumentation prior to restart.
The TS amendment request met a commitment in a licensee letter dated February 26, 1993. The letter requested a temporary waiver of compliance (TWOC) to Limiting Condition for Operation 3.8.9.b that requires that if less than one channel of the CRSLI is operable, and if a channel can not be restored to operable status within 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br />, the reactor must be placed in at least Mode 4 within the next 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />. Operable status, in this instance, required adherence to the 18 month channel calibration interval requirement for the CRSLI in Table 4.8.9-1 which was part of Amendment No.141, issued on January 27, 1993, and to be implemented on February 26, 1993.
The TWOC was granted by the staff verbally on February 26, 1993, and in a letter dated March 2, 1993, to preclude a plant shutdown to conduct the channel calibration.
i Technical Specification Table 3.8.9-1 specifies the accident monitoring l
instrumentation which shall be operable to ensure sufficient information is available on selected plant parameters to monitor and evaluate them during and following a design basis accident. Technical Specification Table 4.8.9-1 l
specifies the surveillance interval requirements necessary to ensure continued operability of the post-accident monitoring inst, a e.ation. Two channels of CRSLI are required to be operable in Modes 1, 2,
, b id 7.
With less than the required number of channels operable (2), but not ' ss than the minimum number operable (1), operations may continue for a period of time not to exceed 7 i
days. With less than the minimum number operable (1), operations may continue for a period of time not to exceed 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br />, if the minimum number of operable channels or the required number of operable channels are not restored within the required time frames, the unit must be placed in Mode 4 within the next 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.
9305140189 930504 PDR ADOCK 05000295 P
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Prior to implementation of Amendment No. 141, there was no CRSLI TS l
calibration requirement, and the licensee calibrated them every 36 months.
l Upon implementation of Amendment No. 14), a calibration interval of 18 months was added to the TS. The amendment request was submitted on November 22, 2
1991, and the licensee reviewed the surveillance requirements affected by it while review by the staff was in progress. However, the calibration interval was not changed from 36 months to 18 months. Since the CRSLI were within the interval specified in the surveillance scheduling program and would still be within the 36 month interval prior to the following refueling outage, the CRSLI were not calibrated during the Unit I refueling outage in the spring of 1992.
Consequently, the Unit 1 CRSLI would not have been within the calibration interval of Amendment No.141 upon its implementation, whereupon both channels would have had to be declared inoperable and a shut down to i
Mode 4 required.
2.0 EVALUATION The CRSLI provides indication in the main control room by energizing two channels of lights at different sump levels.
In the event of a design basis loss of coolant accident, reactor coolant and injection water would collect in i
the containment recirculation sump during the injection phase and be recircu-lated back to the reactor coolant system by the residual heat removal (RHR) centrifugal charging and safety injection pumps during the recirculation phase.
The recirculation phase begins before the refueling water storage tank (RWST) is completely empty to ensure that all pipes are kept filled with water and i
that adequate net positive suction head (NPSH) to the emergenc. core cooling i
system pumps is maintained. The emergency operating procedure (EOP) for loss of reactor or secondary coolant uses RWST level and RWST low level alarms as the primary indicators to the operator that transfer to cold leg recirculation is required.
The E0P for transfer to cold leg recirculation directs the i
operator to verify adequate recirculation sump level by the CRSLI lights or i
containment recirculation sump wide range level indication and requires either RWST low level alarms or indicated RWST low level prior to securing suction from the RWST.
Both the RWST level instruments and the containment water level (wide range) instruments are required to be operable per specification 3.8.9.b.
Thus. the CRSLI provides backup and not primary indication that adequate water is available in the containment recirculation sump. The CRSLI provides indication only, and no safety function actuation.
The licensee reviewed calibration data and work requests for the 36 month surveillance intervals since 1977 for both Unit 1 and Unit 2 CRSLI and found 1
only two failures.
These failures were associated with Unit 2 instruments ard i
were determined to be the result of failed light bulbs. These light bulb 1
f ailures would be detected during the monthly channel check, which was implemented by Amendment No.141 and which verifies the operability of the indicator light circuitry.
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f Other than a forced outege to perform the channel calibrations prior to the next refueling outage, the unit could be shut down or the calibrations could i
be conducted during power operations. The integrity of the reactor vessel and other components of the primary system can be adversely affected by the number of thermal transients that they experience during their lifetime.
It is therefore considered prudent to avoid such transients as long as the health i
and safety of the public are protected. The historic reliability of the CRSLI indicates that absent any information to the contrary, the CRSLI may be considered operable based on the former 36 month calibration interval and cycling the plant through the thermal transient of a plant shutdown to calibrate them is unwarranted. Although the calibrations could be performed l
at power, the licensee has provided data that indicate that during the approximately 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> required, the personnel would accumulate high radiation doses. Therefore, in the interest of maintaining doses as low as reasonably achievable, it is not considered prudent to perform the calibrations during power operations.
l The historic reliability of the CRSLI indicates that calibrations performed at l
the 3 year interval are adequate to consider these instruments operable until l
they are calibrated during the next refueling outage.
In addition, the RWST level instrument channels and the containment water level (wide range) instrument channels are required to be operable by Specification 3.8.9.b and are available to provide indication of the status of containment water level should the CRSLI fail.
Based on its review, staff considers the licensee's l
amendment request for a one-time extension of the calibration interval of the containment recirculation sump level instrumentation until the next Unit 1 i
refueling outage acceptable.
Ir, addition tc the change involving the CRSLI, the footnotes contained in l
Accident Monitoring Instrumentation Tables 3.8.9-1 and 4.8.9-1 that provide provisions associated with the twelfth refueling outage for Units I and 2 have l
been deleted since this refueling outage has been completed for both Units.
Deletion of these footnotes is considered editorial in nature since the l
refueling outage for these allowances has been completed and is acceptable.
3.0 STATE CONSULTATION
In accordance with the Commission's regulations, the Illinois State official was notified of the proposed issuance of the amendment. The State official had no comments.
4.0 ENVIRONMENTAL CONSIDERATION
7 The amendment changes a requirement with respect to the installation or use of' a facility component located within the restricted area as defined in 10 CFR Part 20. The NRC staff has determined that the amendment involves no significant increase in the amounts, and no significant change in the types, l
of any effluents that may be released offsite, and that there is no significant increase in individual or cumulative occupational radiation exposure. The Commission has previously issued a proposed finding that the
l amendment involves no significant hazards consideration, and there has been no public comment on such finding (58 FR 16858). Accordingly, the amendment i
meets the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9). Pursuant to 10 CFR 51.22(b), no environmental impact statement or environmental assessment need be prepared in connection with the issuance of the amendment.
5.0 CONCLUSION
The Commission has concluded, based on the considerations discussed above, that:
(1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, (2) such l
activities will be conducted in compliance with the Commission's regulations, i
and (3) the issuance of the amendment will not be inimical to the common defense and security or to the health and safety of the public.
Principal Contributor:
C. Shiraki Date: May 4, 1993 i
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