ML20059A708
| ML20059A708 | |
| Person / Time | |
|---|---|
| Site: | Arkansas Nuclear  |
| Issue date: | 08/17/1990 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20059A706 | List: |
| References | |
| NUDOCS 9008230181 | |
| Download: ML20059A708 (2) | |
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SUPPLEMENTAL SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION i
RELATED TO THE SAFETY PARAMETER DISPLAY SYSTEM (SPDS)
ISOLATION DEVICE TEST RESULTS I
ARKANSAS POWER AND' TIGHT C0ftPANY ARKANSAS NUCLEAR ONE. UNIT NOS. 1 AND 2 DOCKET NOS. 50-313 AND 50-368 1.
INTRODUCTION l
By letter dated July 31, 1989, the NRC staff transmitted a Safety Evaluation l
(SE)regardingtheSPDSisolationdevices.
The SE concluded that the devices used were acceptable. However, there was one issue which remained open due to an anomaly discovered in one device during the maximum credible fault-
[
testing. As a result, the licensee comitted to analyze the device and the j
test results.
By letter dated February 28, 1990, the licensee forwarded the result of the analysts with the conclusion that the device will maintain electrical isolation during fault conditions, and therefore, is acceptable.
This SE provides the staff's evaluation of the licensee's analysis and conclusion, t
2.0 EVALUATION I
The SE op(en issue involved the qualification of the Rochester Instrument Systems RIS)Model 50-1302 isolation device. To resolve the open issue, the-licensee comitted to analyze the device, including the maximum credible fault-testing.
The tests reported in the [[letter::05000313/LER-1988-009, :on 880922,three Inoperable Snubbers Discovered on safety-related Piping Sys.One Snubber Failed Due to Spec of Undersized Snubber & Other Two Found W/Inadequate Travel Remaining for Thermal Growth|February 28, 1989 letter]] were performed using a maximum credible fault of 120VAC 9 20 amps.
Functional tests, dielectric Withstand voltage tests, shorts grounds and open circuit tests were also completed. Atotaloffourisolatorsweretested. During the fault testing, the isolation device internal fuses were jumpered. The tests demonstrated that a fault applied to the non-Class 1E side of the device will have no noticeable-effect on the operability or function of the Class IE input side. The maximum credible fault applied in the transverse mode resulted in the destruction of an isolator. The destruction of the isolator was an expected result and-the required electrical isolation was maintained.
One anomaly was discovered during the testing on one of the four. isolation:
devices. After the maximum credible fault was applied, the device started to draw a larger amount of current from the power supply than its initial 71mA.
The licensee continued the test and after 86 minutes the device drew enough -
= power to blow the two-amp fuse in the power supply line. The Class 1E input i
side remained isolated. The licensee reported, at first, that they believed l
- the anomaly may have been caused by a device which was originally faulty prior l
to testing.
i 9008230181 900917 PDR ADOCK 05000313 P
PDC j
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- 2-s To verify the root cause of the anomaly, the licensee obtained an independent analysis which concluded that the failure was due to a different design configuration of the specific device.
This specific device changed the damage of the maximum credible fault testing such that the complete open circuit created in the other three devices did not occur in the fourth.
The evaluation also concluded that the isolator's internal fuse, which was jumpered for the test, would most likely have blown before the power supply fuse and would have prevented the anomaly from occurring.
3.0 CONCLUSION
During the tests, the devices successfully isolated the non-Class 1E fault from propagating and damaging the Class 1E side. The anomaly described above did not impact the Class 1E side and would be prevented by the internal fuse which will be in place during plant operation.
Based on the above information, the staff has no further questions and concludes that the RIS S0-1302 isolation device is acceptable for use at ANO Units 1 & 2 for interfacing the SPDS with Class IE circuits.
Dated: August 17, 1990 Principal Contributor:
J. Stewart, SICB l
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