ML20009C330
| ML20009C330 | |
| Person / Time | |
|---|---|
| Site: | Zion File:ZionSolutions icon.png |
| Issue date: | 07/14/1981 |
| From: | Tramm T COMMONWEALTH EDISON CO. |
| To: | Harold Denton Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8107200467 | |
| Download: ML20009C330 (6) | |
Text
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'N Commonwe:lth Edison O ) One First National Plaza, Chictgo, lilinois O-Address Reply to: Post Office Box 767 Chicago, Illinois 60690 w
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July 14, 1981 S
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U Mr. Harold R. Denton, Director C
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U.S. Nuclear Regulatory Commission M
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Washington, DC 20555
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Subject:
Zion Station Units 1 and 2 Seismic Qualification of Auxiliary Feedwater Systems NRC Dockets 50-295 and 50-304 Reference (a):
February 10, 1981, letter from D. G. Eisenhut to All Operating PWR Licensees
Dear Mr. Denton:
Reference (a) requested information regarding the seismic design of Zion Station's auxiliary feedwater systems.
Attachment A to this letter contains the r equested information.
In general, no plant changes are necessary.
One (1) signed original and thirty-nine (39) copies of this letter are provided for your review.
Please address questions regarding this matter to this t
Very truly yours, fk ofM+""
T. R. Tramm Nuclear Licensing Administrator Attachment cc:
Zion Resident Inspector fo0I l
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ATTACHMENT A Additional Inforit.ation Regarding Zion Auxiliary Feedwater System Seismic Design
System Design
The auxiliary feedwater system at the Zion Station has been designed as Seismic Class 1 with the exception of the primary water and supply path.
This non-seismic portion includes the systera piping f rom the condensate storage tank (CST) to a motoriztd valve at the suction of the auxiliary feedwater pumps.
The design of the auxiliary feedwater system does ;nclude a secondary water and supply path that is desinged as Seismic Class 1.
This seismic portion includes the system piping from the Seismic Class 1 service water system to the Seismic Class 1 portion of the suction piping of the auxiliary feedwater pumps.
All Seismic Class I components of the auxiliary feedwater system are housed within structures that are protected from missle and/or tornado demage.
(Reference Zion FSAR Section 0.7 and Figure 6.7-1)
In addition the auxiliary feedwater system at the Zion Station has been designed, constructed, and maintained (and included within the scope of seismic related Bulletins 79-02, 79-04, 79-07 79-14, and 80-11 and IE Information Notice 80-21) to withstand a Safe Shutdown Earthquake (SSE).
Table 1 contains the relevant FSAR design references for Zion's auxiliary feedwater system.
Additional seismic qualification references can be found in Table 2.
These references provide the required descriptions of the methodologies and acceptance criteria including methods employed, seismic input, load combinations, which include the SSE, allowable stresses, qualification testing and engineering evaluattons performed.
Operating procedures In the event it is necessary to switch from the primary water and supply path to the secondary water and supply path, Zion Station has i
developed an operating procedure that is to be followed to accomplish this task.
This procedure is quite detailed and is based upon CST level.
This procedure is divided into two sections with two important I
referenced appendices.
The first section details operating procedures for a slow, steady loss of CST level while the second section details operating procedures for a sudden uncontrolled loss of CST level.
Each procedure section provides level setpoints for continued operation, unit shutdown, tank unit cross-ties, and AFW pump suction transfer to the service water system along with appropriate diection for subsequent action.
In addition, the first appendix proviaes a curve showing CST level requirements including " caution" and " unsafe" tank level regions.
The second appendix provides detailed operator instruction for switching from the CST to the service water system including pump operation sequencing, valve lineups, flow verification, and pump flos balancing.
This procedure is maintained on file at the Zion Station and is part of Zion Station's abnormal operating procedures program.
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i In accordance with the NRC request, a "walkdown" was conducted at the Zion Station of the non-seismically qualified portion of the Auxiliary Feedwater System.
Again, the non-seismic oortion includes the system piping from the CST to a motorized valve at the suction of the auxiliary feedwater pumps.
(Reference Zion FSAR Figure 6.1-l).
This walkdown was conducted by personnel who were involved with the initial design, current maintained design, and who are experienced in the i
analysis, design and evaluation of structures, systems, and components.
i This walkdown was conducted to evaluate the adequacy of the current I
design and to verify that the "as-installed" system is in accordance with the original plant requirements.
Based upon the results of this walkdown it it our judgement that this pioing system is adequately designed and installed in accordance eith the original plant requirement.
Therefore, we are not proposing the l
installation of any additional supports or restraints for this portion of the auxiliary feedwater system.
However, station personnel will conduct i
a general maintenance program for all hangers on this system tn tighten or replace bolts, tighten turnbuckles, and to adjust pipe attachments.
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i TABLE 1 4
W AUXILIARY FEE 0 WATER SEISMIC QUALIFICATION i
i 1.
Pumps / Motors:
Reference Zion FSAR paragraphs 6.7.1, 6.7.2, 6.7.3 j
(Motors; Question 4.23 page Q4.23-5).
2.
Piping:
Reference Zion FSAR paragraphs 6.7.1, 6.7.3, Figures 6.7-1, 1.2.1, Figures 1.2-17 thru 1.2-52, and Question 4.30, Question 4.23.
3.
Valves / Actuators:
Reference Zion FSAR paragraphs 6.7.1, 6.7.2, 6.7.3, and Figure 6.7-1.
4.
Power Supplies:
Reference Zion FSAR paragraphs 8.4.1.4 (page 8.i-6) and Question 5.85.
In addition CECO is actively pursuing this item
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in accordance with IE information notice 80-21.
5.
Primary Water and Supply Path:
Reference Zion FSAR paragraph 6.7.3,
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and Figure 6.7-1.
6.
Secondary Water and Supply Path:
Reference Zion FSAR paragraph 6.7.3, and Figure 6.7-1.
1 7.
Initiation and Control System:
Reference Zion FSAR Ouestion 7.24 page 7.24-1.
8.
Structures Supporting or Housing These AFW System Items:
Reference Zion FSAR paragraph 6.7.1 and Question 4.26 (page Q4.26-1).
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lABLE 2 Zion FSAR References Section Title 1.2.1 Seismic Criteria-Methods of Anals.is for Class I, II & III.
1 Figure 1.2-17 Response Spectra (various buildings and elevations)
Question 4.26 Seismic Design Basis considering the effects of Vertical Seismic Loads on Class I Structures.
Question 4.30 Seismic Design Criteria of Class I Piping.
Question 4.23 Seismic Analysis for Class I Systems.
Question 4.23-7 Computer Code WESTDYN used for Dynamic Analysis.
Question 4.24 Calculations for Seismic Excited Mode.
Question 4.25 Equipment and Flow Response Spectra.
Question 4.27 Floor Response Spectra.
Question 4.28 Seismic System Analysis.
Question 4.29 Seismic Effects of Class II Piping Systems on Class I Piping.
Question 4.31 Seismic Design Criteria Class I Mechanical Components.
Question 4.32 Field Location of Seismic Supports.
Question 4.33 Seismic Design Basis.
Question 4.33.1 Design Organizations.
Question 4.33.2 Interchanges and Coordination among Design
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Organizations.
Question 4.33.3 Design Control.
Question 4.33.4 Purchase Specifications.
Question 4.50 Class I Piping Stress Limits.
Question 4.52 Vertical Load Factors.
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. 'uestion 4.53 Dynamic Response Spectra Analysis of Class Q
I Piping.
Questior 4.54 Floor Response Spectra Peaks.
Ques + ion 4.55 Rigidity of Components.
Question 4.57 Equipment Seismic Design Criteria.
Question 4.58 Damping Ratios.
Question 4.60 Example Piping System Seismic Clasras I &
II.
Question 4.64 OBE-DBE.
Question 4.67 Constant Vertical Load Factor.
Question 4.68 Simplified Dynamic An& lysis.
Question 4.69 Floor Response Spectra.
Question 4.70 Threshold of Rigidity.
Question 5.85 Seismic Reaction from Cable Trays.
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