ML20116L002
| ML20116L002 | |
| Person / Time | |
|---|---|
| Site: | 05200001 |
| Issue date: | 10/09/1992 |
| From: | Mcsherry A GENERAL ELECTRIC CO. |
| To: | David Diec NRC |
| Shared Package | |
| ML19310D443 | List: |
| References | |
| NUDOCS 9211180128 | |
| Download: ML20116L002 (1) | |
Text
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October 9,1992 T 0: D AVE DIEC. NRC NRR AltT MCSilERRY,GE [
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SCHJECT: ABWf< $USCEPTIEll.!TY TO ISOLA ~IlON OF RIIIUSDC ON LOSS OF POWER The AllWR Shutdown Risk Report states that,unlike the operatingIlWRs,the AllWR design will not cau>e isolation of the RIIR/SDC function on ins of RPS AC power. Per your request, the following discunion supplies more detall on the AllWRl>olation system deelga and w hy spurious isolations uill not occur on loss of AC pow er.
For operating IlWils, loss of AC pcwcr to the RPS MG wts results in a reactor trip and Isolation of certain systems attarhed to the HPV. One of the sptcms that is isolated is the RHR/SDC. This is a fall sa'e design that is intended to p.*otect the core from lots of pow er transients. When the plant is shutdow n though, temporary lon of SDC will occur if RPS pow er is internspted.
In the ABWit, the HPS, ECCS, and isolation functions are controlled by the $afety System Logic The attached settion of the ABWR $$LC design specification contains and Control (SSLC) splein.
the requiremtet that the SSLC isolation function be powered by 125 VDC which is backed up by Cir.s3 JE batteries (2.2.2.6 a). Thus, a lon of one AC poner supply to the SSLC will not result lu a RIIIUSDC isolation signal. In fact, lots cf < h AC to the $SLC will not result in any trip or isolation signals unleu DC power is also affected or the h.ss of pow er results in plant conditions requiring isolation. The AHWR Cians IE batteries are dol;;ned for at Icast 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> of operation following; loss of AC powtr. Thl la adequete time to stilft SDC to an unaffected division or to restore AC power to the SSLC.nverters.
The ABWR SSLC is designed for high plant availability (!.e., minimintion of spurious trips) while also ensucing that plant trips and Soletion will orrur when necJed due to trtual plant conditions requirbg these. functions, if you need additionalinformation or clarlfication of the AllWR SSLC. please contact me at (40t')
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