ML20073E163
| ML20073E163 | |
| Person / Time | |
|---|---|
| Site: | Grand Gulf  |
| Issue date: | 03/26/1976 |
| From: | Hou S Office of Nuclear Reactor Regulation |
| To: | Knight J Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML20071F735 | List: |
| References | |
| FOIA-93-375 NUDOCS 9409280279 | |
| Download: ML20073E163 (3) | |
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UNITrD ST AILS g3 NUCLEsR REGULATORY COMMISSION l
WASHINGTON, D. C. 20555
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MAR 2 61976 l
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l J. P. Knight, Chief Mechanical Engineering Branch Division of Systems Safety l
MEETING WITM BECHTEL RECARDING MAIN STEAM TUNNEL DESIGN At our request, a meeting between Bechtel/Gaithersburg and NRC personnel j
was hdid on March 17, 1976 in Bethesda. Af ter several previous rnectings, q
this follow-up meeting was a continued HEB-APCSB effort to complete our review of Bechtel proposed main steam tunnel design concepts (see references 1 and 2).
Discussions were centered on the basis to define the break exclusion zone and locds to be used in the main steam tunnel design as indicated in the attached meeting agenda.
This meeting concludes the following:
i 1.
The Concept #2 as described in Reference 1 is acceptable from the l
standpoint of lower piping stress level, less congestion to hinder inservice inspection, and better protection of the ' third valves'
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on the main steam lines.
Thus, overall system safety for protection against the pipe rupture is enhanced, eP 2.
Although piping inside the steam tunnel is designed to low stress level, more frequent inservice inspection, etc., in accordance with the break exclusion criteria of MEB 3-1, on the request of the staff, Bechtel j
agreed to design the tunnel structure and its venting capability based 3
on thermal and pressure loads of a non-mechanistic steam line break instead of the break of 10" RCIC line as they initially proposed.
The break area shall be,cquivalent to a full flow area of the main steam line.
This is consistent with our current position (i.e.,
guide pipe design at containment penetration) to ensure separation of safety systens from pipe rupture effects.
I 3.
Bechtel agreed to design the 10-1nch RCIC inside the tunnel to meet i
the break exclusion criteria of MEB 3-1 in the Grand Gulf application, and the line shall be restrained near the valve. A complete separation of the RCIC line from the steam tunnel shall be considered in the future plant design.
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J. P. Knight In addition, Bechtel agreed to send to us minutes of the meeting and the conclusions of this meeting will be reflected in the Final Safety Analysis Report to be subtitted for the Grand Gulf application.
j,k _G km Shou-nien flou t!cchanical Engineering Branch i
Division of Systems Safety cc w/ encl:
R. lleineman, SS R. !!accary, SS R. Tedesco, SS C. Long, SS V. Benaroya, SS D. Fischer, SS R. Bosnak, SS H. Brammer, SS P. 11ea r n, SS E. Butcher, Fl!
References:
1.
" Main Steam Tunnel Design" presented by Bechtel in the NRC/Bechtel meeting on December 11, 1975.
2.
Letter, Mr. R. L. Ashley of Bechtel to Mr. R. Maccary, dated February 18, 1976.
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flecting Agenda CONCEPTS IN !!AIN STEAtt TUNNEL DESIGN j
NRC-Bechtel,!! arch 17, 1976
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1.
To demonstrate adequate system separation - APCSB A.
Discuss plant layout B.
Define non-mechanistic pipe break loads for the main steam
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tunnel design.
i II.
To demonstrate adequate system protection - MEB A.
Discuss design criteria:
1.
Should branch line connections be terminal ends and hence the break locations?
1 2.
Should the application of Eqns. (12) and (13) be extended to ASME Class 1 piping inside containment?
B.
Clarify design considerations:
1.
Specify upset transients used as a loading condition in the comparison of concepts #1 and #2.
a 2.
Clarify computation methods used to define stresses in the concept comparison.
3.
Identify safety-related equipment and redundant safety systems in the main steam tunnel, and' justify their operability under the effects of pipe rupture.
i 4
In concept #2, identify consideratiens to optimize the location of the Auxiliary Building wall.
5.
In concept #2, provide more detailed justification to demonstrate that operability of active valves is more reliable.
i C.
Discuss the necessity to extend the "no break zone" - Are there any options in addition to concepts #1 and #27
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