ML20049J252
| ML20049J252 | |
| Person / Time | |
|---|---|
| Site: | Calvert Cliffs  |
| Issue date: | 02/25/1982 |
| From: | Lundvall A BALTIMORE GAS & ELECTRIC CO. |
| To: | Clark R Office of Nuclear Reactor Regulation |
| References | |
| GL-81-14, NUDOCS 8203120315 | |
| Download: ML20049J252 (4) | |
Text
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o BALTIM ORE GAS AND ELECTRIC CHARLES CENTER P. O. BOX 1475. BALTIMORE, MARYLAND 21203 ARTHUR C. LONOVALL, JR.
vict PRCSCEN' tu m February 25, 1982 m
f NECjg;,DD Office oi.uclear Reactor Regulation S
U. S. Nuclear Regulatory Commission 3
s OJ Washington, D.C.
20555 9
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Attn:
Mr. Robert A. Clark, Chief
(
Operating Reactors Branch #3 9
Division of Licensing
)
Subject:
Calvert Cliffs Nuclear Power Plant Unit No.1 and 2, Docket No. 50-317 and 50-318 Auxiliary Feedwater System
References:
(a) Letter from A. E. Lundvall, Jr. to R. A.
Clark, dated June 30, 1981. Response to Generic Letter 81-14 Seismic Qualification of Auxiliary Feedwater Systems.
(b) Letter from R. A. Clark to A. E. Lundvall dated January 6,1982, same subject.
Gentlemen:
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Reference (a) was our response to your request for information in Generic Letter 81-14. In our response, we discussed the seismic design basis of our Auxiliary Feedwater (AFW) System.
Reference (b) requested that we respond to some additional questions.
It should be noted that we have opted to use the planned modifications to our AFW system as a basis for some of our responses. Scheduled completion of the modifications is discussed in the response to Question 2.
Our responses are as follows:
s (1) The only branch connections on the AFW system are discussed as follows:
(a) Pump Turbine Exhaust Piping: This piping has no isola-tion valves. The steam exits the AFW pump turbine and dissipates to the environment. Further discussion of this item is contained in the response to Question 8.
hi 8203120315 820225 PDR ADOCK 05000317 P
' February 25, 1982 1.
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(b) Chemical 4
. tion Piping: This piping has one isolation valve lot..
in the seismio AFW pump room.
This valve is kept noi a ly shut. A second valve, located in the non-seismic turbine building is also kept normally shut.
Further discussion of this item is discussed in the response to Question 7 (c) Recirculation Piping:
The recirculation piping has two normally open valves.
One is located in the AFW pump
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room. These valves are required to be open during opera-
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tio6 of 'thn. pump, and can not be normally or automatically shut. This piping is seismically mounted to a point down-stream of thi flow resti-iction orifices. Should the pipe bresk off downptream of these orifices, no problems would rechlt, since tSe increase in flow through the line vould be minimal in comparison to that available to the pump
- suction. Therefore, the required amount of AFW vould be available to the steam generators.
Ao a matter of practice', the boundaries of these analyses are established by three-way orthogonal supports.
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(2) The AIN system modifications, which include upgrading circuit-carrying conduits'and the initiation / control systems, are pre-sently planned to be_ comp]eted as follows:
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Unit 1:
Fall 1983 Unic 2:
Fall 1982 (If equipment deliveries are not met, this work will'be delayed to the
.2 Spring, 198h outage.)
The tiemic I addition line seismic supports have been designed and vill bs iretalled by January 1,1983.
(d A valkdown was performed for the chemical addition lines for puhoses of designing additional seismic supports. The non-seismic control systems components are presently being up-l graded to seismic as stated on Page T of Reference a; there-fore, no special valldown te evaluate their non-seismic instal-lations is necessary. All the engineering work is being per-formed by the corporation which originally designed the facility.
(h) The AFW system items thich are housed and supported within the Turbine Building and which are seismic Class I are completely enclosed and supported within the AFW ptmp room. This rein-forced concrete struci.ure rests on an independent foundation and was designed and constructed to seismic Class I criteria.
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' February 25, 1982 (5) For two-inch and smaller Category I piping, a field installa-tion manual and standard support designs were provided so that field engineers could proper'y select and locate pipe supports.
The manual's intent was to provide a set of instructions for proper placement of supports in small bore piping systems to i
satisfy thermal, seismic, and deadveight stresses.
Generally, the systems were designed to limit thermal stresses to 15,000 PSI and natural frequency of the piping system to be in the rigid range (20 CPS and above). The resulting stresses in the piping system due to a-seismic event vill be minimal in the rigid range, compared to the allowable SSE stress limits.
(6)Section IV, part 4, was erroneously titled " Power Supplies";
It should have been titled simply " Electrical". The power supplies associated with the AW system are class IE ar dis-cussed on page 4 of our submittal.
(7) The section of chemical addition line from the AW pump suction to a point beyond the existing normally shut manual valve vill be upgraded to seismic Category I (see response to Question (1)). The seismic portion of this pipe vill be bounded by a three-way orthoganal support. This is adequate support to preclude failure in the seismic portion.
(8) Crimping was not a consideration in the original design of -
the AW system and therefore the exhaust piping of the AW '
pump was not designed with this in mind.
If an evaluation of the effects of crimping is to be a requirement for Calvert Cliffs then much more study time would be needed to formulate criteria'on failure modes, material susceptability, design assumptions for fixes and the like. It is suggested that this type of evaluation is beyond the intent of Generic Letter 81-14 which requests the licensee to identify "practi-cally correctable deficiencies that may exist." Redesigning the pump turbine exhaust piping would be expensive and imprac-tical.
In addition, during the modifications discussed in the response to Question 2, we vill be installing an electric driven AW pump in each unit. The motor driven pump will have an indepen-dent discharge header up to the tie-in point with the existing AW header, downstream of the CV's for the stream driven pumps.
The motor driven Wep has a single discharge line which splits to feed each individual steam generator. This pump will be installed in the seismic category I Auxiliary Building. All
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February 25, 1982 installation of piping, motor, and controls for this pump will be to seismic category I design criteria. A cross connect will be installed between the two motor driven AW pumps. Therefore, Unit 2 could supply Unit 1 with AW if Unit l's steam driven exhaust lines were crimped and Unit l's motor driven pump failed to start. For this reason, there is a high confidence
-that AW will be delivered to the SG's even if a seismic event were to crimp.the AW steam driven pump exhaust lines.
(9) The fact that the seismically qualified manual valves are similar in construction and have similar material properties is the basis for concluding that the seismic behavior of the valves would be similar.
Note: A check valve exists between each containment penetra-tion and the associated steam generator. This was accidentally omitted in reference-Ta).
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A. E. Lundvall, Jr.
Vice President, Supply WCH/tej cc:
J. A. Biddison, Esquire G. F. Trowbridge, Esquire Messrs. D. H. Jaffe - NRC J. C. Ventura - Bechtel P. W. Kruse - CE R. E. Architzel - Resident Inspector i
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