ML071280350
| ML071280350 | |
| Person / Time | |
|---|---|
| Issue date: | 03/29/2007 |
| From: | Michael Scott NRC/NRR/ADES/DSS/SSIB |
| To: | Butler J Nuclear Energy Institute |
| Scott M L, NRR/DSS/SSIB, 415-0565 | |
| References | |
| GSI-191 | |
| Download: ML071280350 (6) | |
Text
LMichael Scott - NRC STAFF REVIEW CONSIDERATIONS FOR BUFFER CHANGES -- ____- Page j From: Michael Scott To: jcb@nei.org Date: 03/29/2007 3:06:15 PM
Subject:
NRC STAFF REVIEW CONSIDERATIONS FOR BUFFER CHANGES John:
Forwarded is s summary of NRC staffs thoughts on review of future buffer changes. Please contact me by return e-mail if you have any questions.
Mike CC: thomas martin;GSI-191
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Subject:
NRC STAFF REVIEW CONSIDERATIONS FOR BUFFER CHANGES Creation Date 03/29/2007 3:06:15 PM From: Michael Scott Created By: mls3@nrc.gov Recipients Action Date & Time nei.org Transferred 03/29/2007 3:06:49 PM jcb nrc.gov OWGWPO01 .HQGWDO01 Delivered 03/29/2007 3:06:28 PM JPB3 CC (John Burke) Opened 03/29/2007 3:35:51 PM REA CC (Ralph Architzel) Opened 04/03/2007 9:15:36 AM nrc.gov OWGWPO02.HQGWDO01 Delivered 03/29/2007 3:06:27 PM EXG CC (Ervin Geiger) Opened 03/29/2007 3:46:08 PM JAG2 CC (Joe Golla) Opened 03/30/2007 7:28:29 AM nrc.gov OWGWPO03 .HQGWDO01 Delivered 03/29/2007 3:06:27 PM DGC CC (David Cullison) Opened 03/29/2007 4:22:44 PM nrc.gov OWGWPO04.HQGWDO01 Delivered 03/29/2007 3:06:59 PM ALH1 CC (Allen Hiser) Opened 03/29/2007 3:43:25 PM DGH CC (Donald Harrison)
MLH3 CC (Michelle Hart) Opened 03/29/2007 3:41:06 PM
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TWGWPO01 .HQGWDOO1 03/29/2007 3:06:29 PM nrc.gov TWGWPO02.HQGWDOO1 03/29/2007 3:06:27 PM nrc.gov TWGWPO03.HQGWDOO1 03/29/2007 3:06:27 PM nrc.gov TWGWPO04.HQGWDO01 03/29/2007 3:06:27 PM nrc.gov Files Size Date & Time MESSAGE 159 03/29/2007 3:06:15 PM Review Considerations for Buffer Replacement 032907.doc 27136 03/29/2007 3:06:14 PM Options Auto Delete: No Expiration Date: None Notify Recipients: Yes Priority: Standard ReplyRequested: No Return Notification:
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NRC Staff Review Plans for Buffer Replacement Amendments 3/29/2007
Background
Several licensees are considering buffer replacements. The NRC encourages such consideration as a potential contribution to addressing the sump clogging potential of chemical effects. Licensees and the Nuclear Energy Institute have asked the NRC staff to delineate its review considerations for these amendment requests.
NRC Staff Review Considerations A change to the chemical intended to buffer the post-LOCA containment pool may impact a number of areas, including chemical effects on sump clogging, dose considerations, corrosion/stress corrosion cracking of materials, and equipment qualification. Considerations for each of these areas are provided below.
The NRC staff expects the licensee applicant to show that the buffer change will result in reduced chemical effects. Since the knowledge base of chemical effects testing continues to develop, licensees should stay current with the available information. The amendment should demonstrate, based on currently available information, a reduction in precipitate (e.g., by providing the output results from the WCAP-16530-NP chemical model for the current and proposed buffer).
The technical basis for chemical effects that demonstrates acceptable head loss and acceptable downstream component interactions assuming plant-specific debris loadings and transport will be evaluated as part of the GSI-191 resolution process, not as part of the buffer amendment process. This technical basis need not be provided in a buffer change amendment request submitted in the interim before the GL 2004-02 deadline (December 31, 2007).
To address dose considerations, the licensee need only show that pH is maintained >= 7, a demonstration sufficient for the staff to conclude that existing assumptions regarding iodine levels in the containment atmosphere remain valid.
For a proposed change to a buffering agent already in use in other U.S.
PWRs (sodium hydroxide, trisodium phosphate, or sodium tetraborate) and projected pH >= 7, no review/consideration of corrosion and stress corrosion cracking is needed. For proposed use of a buffer not currently in use in U.S. PWRs, licensees should consider potential impacts of corrosion and stress corrosion cracking on structures, systems, and components whose continued performance is required post-LOCA. For delayed or no introduction of buffering agents, licensees should consider corrosion and stress corrosion cracking and should also consider chemical effects from the unbuffered ECCS water prior to the introduction of the buffering agent.
Licensees should verify in their submittals that equipment subject to environmental qualification remains within the analyzed EQ envelope in the presence of the proposed new buffer.
The NRC staff expects that Technical Specifications will be updated as part of buffer change amendments to indicate the name of the new buffer.