ML20046B519
| ML20046B519 | |
| Person / Time | |
|---|---|
| Site: | 05200001 |
| Issue date: | 07/30/1993 |
| From: | Fox J GENERAL ELECTRIC CO. |
| To: | Poslusny C Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 9308040327 | |
| Download: ML20046B519 (4) | |
Text
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GENucle:r Energy Genera!Dectoc Company 175 Curtner Avenue. San Jose. CA 95125 3uly 30,1993 Docket No. STN 52-001 Chet Posiusny, Senior Project Manager Standardization Project Directorate Associate Directorate for Advanced Reactors and License Renewal Office of the Nuclear Reactor Regulation
Subject:
Submittal Supporting Accelerated ABWR Schedule -ISLOCA
Dear Chet:
This transmittal responds to Son Ninh's July 28,1993 letter pertaining to the staff's review of my July 9,1993 ISLOCA letter. The following address the three issues resulting from the staff's review:
1.
Heat exchanges, flanges and pump seals, etc. are addressed in Page 7 (end of Section 3M.7.1) of my July 9,1993 letter.
I 2.
Replacement Pages 9 and 10 (attached) clarify the role of the operator in producing ISLOCA situations.
3.
Replacement Page A-44 (attached) clarifies the upgrade description and the downstream interfaces for the Makeup Water System Purified.
Please provide copies of this transmittal to Mark Rubin and George Thomas.
Sincerely, 3 0>C Jack Fox Advanced Reactor Programs cc: Alan Beard (GE)
Norman Fletcher (DOE)
BillTaft (GE)
JIW237 Donnon
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Page 9 System SSAR Affected Sheet Figure No.
Nos.
- 10. Makeup Water (Condensate) 9.2-4 1
(MUWC) System
- 11. Makeup Water (Purified) 9.2-5 1, 2, 3 (MUWP) System
- 12. Radwaste System (LCW l1.2-2 1,3,7 Receiving Tank, HCW Receiving Tank)
- 14. Sampling (SAM) System Also, see Appendix A for more detail.
The design pressure of the following two tanks was upgraded as a result of the evaluations performed in Appendix A.
SLC test tank RCIC turbine barometric condenser tank Ypive Misalignment Due To Operator Error An important result to observe is that because of the widespread application of the URS boundary for the ABWR design as compared to previously constructed BWRs, misalignment of valves due to operator error j
is a contributor to ISLOCA that has no known consequence. The ABWR design with the ISLOCA URS applied for the boundary described by this report, has extended the increased design pressure (URS) over the full extent of regions that could potentially experience reac or pressure, so that operator misaligned valves will not expose piping to reactor pressure not designed to the URS pressure.
Page 10 The ISLOCA issue that has been dealt with for existing BWRs, where valve misalignment due to operator error was a significant contributor to ISLOCA considerations, had to use the design pressures used for plant construction that were accepted before ISLOCA issues were considered.
As a result, operator error of valve misalignment could possibly result in situations where high pressure might occur in piping regions with design pressures 2
below the current accepted URS design pressure (28.8 kg/cm g),
Additional Onerational Considerations The periodic surveillance testing of the ECCS injection valves that interface with the reactor coolant system might lead to ISLOCA conditions if their associated testable check valve was stuck open.
To avoid this occurrence, the RHR, HPCF, and RCIC motor operated injection valves will only be tested during low pressure shutdown operation.
This practice follows from the guidance given by Reference 3, page 8, paragraph 7.
Although the following is not a new design feature, the RHR shutdown cooling suction line containment isolation valves are also only tested during shutdown operation.
These valves are interlocked against opening for reactor pressure greater than the shutdown cooling setpoint approximately 9.49 kg/cm2 gage (135 psig).
Summary Based on the NRC staff's new guidance cited in References I through 4, the ABWR is in full compliance.
For ISLOCA consider,ations, a design pressure of 28.8 atg or (410 psig) and pipe having a minimum wall thickness equal to standard grade has been provided as an adequate margin with respect to the full reactor operating pressure of 72.1 atg (1025 psig) by applying the guidance recommended by Reference 2.
This design pressure was applied to the low pressure piping at their boundary symbols on the P&lDs, and therefore, impose the requirement on the associated piping, valves, pumps, tanks, instrumentation and all other equipment shown between boundary symbols.
A note was added to each URS upgraded
Page A-4 4
- 11. Makeup Water System Purified 11.1 Upgrade Description The MUWP System is not upgraded due to the extensive nature of the piping distribution, but instead all valves between the interface of potential reactor pressure sources and the Condensate Storage Tank are changed to the lock open type.
This provides a clear path for the release of pressure to the Condensate Storage Tank which is vented to the atmosphere.
The potential reactor pressure sources are the SLC System makeup seal, the RRS ten RIP casing makeup water connections, and shaft (RIP) inflatable seal capped connections.
The piping and valves connected to the RIPS within the primary containment were upgraded to the URS design pressure.
11.2 Downstream Interfaces The Makeup Water System Purified System has p_q further downstream system interfaces that could allow reactor pressure to proceed further than the MUWP System.
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