ML20127L817
| ML20127L817 | |
| Person / Time | |
|---|---|
| Site: | Beaver Valley |
| Issue date: | 06/11/1985 |
| From: | Carey J DUQUESNE LIGHT CO. |
| To: | Varga S Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8506280149 | |
| Download: ML20127L817 (2) | |
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Telephone (412) 393-6000 Nuclear Group s$pYgp#
June 11, 1985 ort, PA 15077-0004 Director of Nuclear Reactor Regulation United States Nuclear Regulatory Commission Attn: Mr. Steven A. Varga, Chief Operating Reactors Branch No.1 Division of Licensing Washington, DC 20555
Reference:
Beaver Valley Power Station, Unit No. 1 Docket No. 50-334, License No. DPR-66 Reactor Trip Response Time Gentlemen:
We have reviewed your letter dated April 22, 1985, Technical Specifica-tions For Reactor Trip System Instrumentation Response Time Surveillance Requirements, requesting that we determine whether or not the overtemperature delta T trip function response time is consistent with the safety analysis assumptions.
The review has been performed and we have concluded that a change to Table 3.3-2, Reactor Trip System Instrumentation Response Times, is required to revise the overtemperature delta T response time from 6 seconds to 4 seconds. The safety analysis assumption includes a 2 second delay attribut-able to coolant transit and thermal lag response time associated with the RTD bypass manifold coolant temperature measurement.
The response time that can be measured is the time interval from when the parameter exceeds its setpoint at the channel sensor until loss of gripper coil voltage and does not include the transit and thermal lag time. Therefore, a technical specification change will be initiated to revise the overtemperature delta T response time to 4 seconds.
Related to the above, we have discussed circuit modifications on the delta T and Tave summators with an NRC staff member.
The modifications have been proposed as a means of filtering circuit noise from the instrument loop to avoid spurious trips generated on one channel while another channel was placed in the tripped condition for surveillance testing.
The NRC staff member has requested that we investigate the need for a technical specifica-tion change to revise tne Table 2.2-1 overtemperature delta T and overpower delta T equations to include additional time constants used in the lead-lag compensator for the delta T and Tave circuits.
In response to this request, we have contacted Westinghouse and we are pursuing an investigation of the required lead-lag compensation.
Very truly yours, J
OS V Vice President, Nuclear
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8506280149 850611 DR ADOCK 05000334
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B:avor Valley Pow:r~ Station, Unit No. 1 i
'Dockst No. 50-334, License No. DPR-66 Reactor' Trip Response Time Page 2 Mr. W. M. Troskoski, Resident Inspector cc:
U. S. Nuclear Regulatory Commission Beaver Valley Power Station Shippingport, PA 15077 U. S. Nuclear Regulatory Commission c/o Docunent Management Branch Washington, DC 20555 Mr. Peter Tam, Project Manager U. S. Nuclear. Regulatory Commission Phillips Building Washington, DC 20555 Mail Stop 438 -
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