ML20202J195
| ML20202J195 | |
| Person / Time | |
|---|---|
| Issue date: | 12/10/1997 |
| From: | Lobel R NRC (Affiliation Not Assigned) |
| To: | Butler J NUCLEAR ENERGY INSTITUTE (FORMERLY NUCLEAR MGMT & |
| References | |
| GL-97-04, GL-97-4, NUDOCS 9712110080 | |
| Download: ML20202J195 (2) | |
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December 10,1997 John Butler, NEl As you know, following our presentations at the NEl meeting on NRC GL 97-04 in Baltimore on l
December 2,1997 Bill Long and I were asked several questions that we could not answer. We committed to provide you with answers at a later date. Attached are the questions and answers.
A copy will be placed in the NRC oublic document room today.
- 1. There was a discussion of the relationship between the emergency operating procedures and NPSH at a BWROG meeting with the NRC staffin November 1997. What were the specifics of i
the discussion?
A meeting was held between NRC staff and members of the BWROG on November 19,1997. At this meeting a question was raised by the NRC staff concerning whether the NPSH calculations for the emergency core cooling system (ECCS) pumps and the containment heat removal pumps are consistent with the emergency operating procedures. The specific concem is the effect on NPSH of the use of containment sprays as specified in the emergency operating procedures.
Containment sprays willlower the containment pressure and may result in a containment pressure less than that assumed in the calculation of NPSH. The BWROG members will examine this issue and respond to the staff.
- 2. Should BWR High Pressure Core Spray (HPCS) and High Pressure Coolant Injection (HPCI) pumps be included within the scope of GL 97-04?
Adequate NPSH must be available for the HPCS and HPCI pumps when they are taking suction from the suppression pool. Therefore, these pumps should be addressed in the response to the generic letter for this mode of operation, This is consistent with the guidance in the section of the generic letter entitled " Requested information".
- 3. Are " piggy-back" pumps (high pressure injection pumps supplied by low pressure injection pumps in recirculation) included in the scope of GL 97-04? Exactly what information is being requested by GL 97-04 forpiggy-back pumps?
The section of the generic letter entitled " Requested Information" states that the requested information applies to " pumps used in piggy-back operation that are necessary for recirculation cooling of the reactor core and containment". The information provided for these pumps should be the same type as requested for pumps which take suction directly from the emergancy sump.
GL 97-04 requests information about NPSH for safety-related pumps in a pressurized water reactor (PWR) only in the recirculation phase of a LOCA. For a BWR, as stated in reply to Question 2, GL 97-04 only applies to safety-related pumps taking suction from the suppression pool during a LOCA. However, even though GL 07-04 applies to safety-related pumps taking suction from the sump or suppression pool, the staff expects that licensees have analyses demonstrating that safety-related pumps have adequate NPSH for all flow paths used to mitigate the consequences of design basis accidents.
- 5. In o e discussion about CrystalRiver Unit 3 in GL 97-04, there was a discussion of Q fo % 0 9712110080 971210 PDR REVGP ERGNUMRC
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uncertaintyin data regarding the required NPSH. What expectations does the staff have about the use of uncertainty with regard to NPSH?
Crystal River Unit 3 Licensee Event Report number 50-302/95-023-002 describes a condition found to e::ist it. which the reactor building (containment) spray flow values used in various i
l appli:ations wa,e inconsistent. In particular, uncertainties in instrumentation which the operator is dir1cted to use by the emergency operating procedures are different from those used in engineering calculations. The licensee stated that This condition may lead to system operation that could potentially challenge long term off site dose limits, Net Positive Suction Head (NPSH) requirements and long term pump flo A criteria estabH"'d by the pump vendor.
The staff does not expect that every value used in an NPSH calcula' ion have m.1 associated uncertainty. However, as illustrated in this case, use of uncertainty values should be consistent.
In addition, there should be sufficient conservatism io account for reasonable uncertainty in the results.
Richard Lobel Containment Systems and Severe Accident Branch Nuclear Regulatory Commission cc: Bill, ong, NRC Kerri Kavanagh, NRC Jack Kudrick, NRC Scott Newberry, NRC PDR e
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