ML033250345
| ML033250345 | |
| Person / Time | |
|---|---|
| Site: | Palisades  |
| Issue date: | 11/12/2003 |
| From: | Domonique Malone Nuclear Management Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| GL-96-006, TAC M96844 | |
| Download: ML033250345 (2) | |
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Committed toft NuarExcep Palisades Nuclear Plant Operated by Nuclear Management Company, LLC November 12, 2003 U S Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 PALISADES NUCLEAR PLANT DOCKET 50-255 LICENSE No. DPR-20 RESOLUTION OF GENERIC LETTER 96-06 WATERHAMMER AND TWO-PHASE FLOW ISSUES - SUPPLEMENTAL INFORMATION (TAC NO.M96844)
By letters dated February 28, 2003 and July 24, 2003, Nuclear Management Company, LLC (NMC) provided responses for the resolution of generic letter (GL) 96-06 waterhammer and two-phase flow issues, respectively. NMC staff recently held telephone discussions with the Nuclear Regulatory Commission (NRC) staff reviewing the referenced responses. The NRC staff has questioned the treatment of offsite power availability during a main steam line break (MSLB). In particular, NMC stated in the referenced responses that the loss-of-coolant accident (LOCA) with a concurrent loss of offsite power (LOOP) is more limiting than a MSLB, with regard to the waterhammer and two-phase flow concerns raised by the GL. NMC also stated in the referenced responses that the MSLB containment response analysis does not assume a concurrent LOOP. NRC staff questioned if the most limiting scenario has been analyzed since a concurrent LOOP has not been considered for the MSLB. NMC is providing the following responses to the Staffs questions.
During a MSLB or LOCA, energy is transferred to the water in the containment air cooler tubes from the containment atmosphere. The dominant heat transfer mode is condensation heat transfer, which is driven by the saturation temperature of the containment atmosphere steam pressure. The MSLB steam pressure profile does not begin to exceed the LOCA steam pressure profile until approximately 100 seconds into the event, which is more than one minute after the first service water pump has started and flow has been restored to the containment air coolers. Consequently, in the context of condensation heat transfer, a LOCA bounds a MSLB.
During a LOCA, the containment atmosphere is saturated, but during a MSLB, the atmosphere is superheated. For this reason, the containment atmosphere is hotter during a MSLB than during a LOCA. The temperature in containment during a MSLB exceeds that for a LOCA for fifteen to twenty seconds prior to restart of a service water pump. Consequently, any heat transfer across the containment air cooler tubes that is driven by differential temperature is greater for a MSLB than for a LOCA. However, because condensation heat transfer dominates all other heat transfer modes, a LOCA environment produces more heat transfer into the air cooler tubes than does a MSLB environment whether offsite power is available or not.
Therefore, a MSLB with a LOOP is bounded by a LOCA with a LOOP. As a result, a separate MSLB with LOOP analysis is not required for GL 96-06 waterhammer or two-phase flow issues.
This letter contains no new commitments and no revisions to existing commitments.
Dan ie Site Vice President, Palisades Nuclear Plant CC Regional Administrator, USNRC, Region Il Project Manager, Palisades Nuclear Plant, USNRC, NRR NRC Resident Inspector - Palisades Nuclear Plant 2