ML22195A217
| ML22195A217 | |
| Person / Time | |
|---|---|
| Site: | Limerick  |
| Issue date: | 07/12/2022 |
| From: | V Sreenivas Plant Licensing Branch 1 |
| To: | Rhoades D Exelon Nuclear, Exelon Generation Co |
| Sreenivas V, NRR/DORL/LPLI, 415-2597 | |
| References | |
| Download: ML22195A217 (27) | |
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EICB Mode Selector Switch: The mode selector switch input to the PPS is shown as an input to the Local Coincidence Logic module in each division of the PPS.
This indicates that the reactor scram function of the Mode Selector Switch may be dependent on PPS functionality to initiate a reactor scram.
6/1/22: The UFSAR only refers to the Mode selector switch scram function as a backup to the RPS manual controls (see Section 7.2.2.1.2.3.1.17, RPS - IEEE 279 (1971),
Paragraph 4.17; not a diverse backup. Therefore, there is no reduction in diversity. As shown in Figure 1, the existing LGS configuration of the Mode Selector Switch and the RPS manual actuation logic share a significant amount of circuitry that feeds into the final actuation circuitry. Although the Reactor Mode Switch is a separate input into the scram circuit, it is not a diverse scram signal. [
)) there is also the PPS Manual Scram (reactor scram push buttons) that interfaces directly to the RPS TUs, bypassing all PPS software as discussed in section 2.1.
Figure 1 - Existing LGS Reactor Mode Switch and RPS Manual Scram Circuitry CONFIRMOP EN