ML19330B328
| ML19330B328 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 07/23/1980 |
| From: | Crouse R TOLEDO EDISON CO. |
| To: | Novak T Office of Nuclear Reactor Regulation |
| References | |
| 635, NUDOCS 8007310380 | |
| Download: ML19330B328 (5) | |
Text
o TOLEDO
%ms EDISON Docket No. 50-?'S A C~ " C P C ' **
.E P*e4 F t u er License No. NPF-3
- m '22:
Serial No. 635 July 23, 1980 Director of Nuclear Reactor Regulation Attention:
Mr. Thomas M. Novak, Assistant Director Operating Reactors Division of Licensing U.S. Nuclear Regulatory Commission Washington, D.C.
20555
Dear Mr. Novak:
This is in response to your letter of June 24, 1980 (Log No. 569) request-ing additicnal information for bypass and reset of Engineered Safety Features for Davis-Besse Nuclear Power Station Unit 1.
The attachment to this letter sumcarizes our response to the items listed in the enclo-s sure to your letter.
Very truly yours, f f 7;-W-RPC:SCJ Attachment dh b/2 ODI 3
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THE TCLECO EO! SON CCMPANY EC!SCN DLAZA 300 MACISCN AVENUE TOLEDO. C-!O 43E52 80 07310380
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Docket No. 50-346 License No. NPF-3 Serial No. 635 July 23, 1980 Toledo Edison Response to KRC Request For Additional Information for Bypass and Reset of Engineered Safety Features for Davis-Besse Unit 1 ITEM 1:
The information presented in your FSAR and your letters of December 13, 1978 and January 18, 1980, is not sufficient to determine if the following requirements are met for the safety signals to all Engineered Safety Features (ESF) equipment.
Therefore, identify and justify all exceptions to the following:
Criterion 1 - In keeping with the requirements of General Design Criteria 55 and 56, the overriding of one type of safety actuation signal (e.g., radiation) should not cause the blocking of any other type of safety actuation signal (e.g.,
pressure) for those valves that have no function besides con-tainment isolation.
Criterion 2 - Sufficient physical features (e.g., key lock switches) are to be provided to facilitate adequate admini-strative controls.
Criterion 3 - A system level annunciation of the overridden status should be provided for every safety system impacted when any override is active.
(See R.G. 1.47).
Criterion 4 - Diverse signals should be provided to initiate isolation of the containment ventilation system. Specifi-cally, containment high radiation, safety injection actuation, and containment high pressure (where containment high pressure is not a portion of safety injection actuation) should auto-matically initiate CVI.
Criterion 5 - The instrumentation and control systems provided to initiate the ESF should be designed and qualified as safety grade equipment.
Criterion 6 - The overriding or resetting of the ESF actuation signal should not cause any valve or damper to change position.
RESPONSES:
Criterion 1: The design goal of the Davis-Besse Safety Features Actua-tion System (SFAS) is to automatically prevent or limit fisson product and energy release from the core, to isolate the containment vessel and to initiate the operation
,f the Engineered Safety Features (ESF) equip-ment in the event of a LOCA as described in Section 7.3 of the Davis-Besse FSAR. The SFAS outputs cannot be blocked unless a safety actuation signal has tripped the system. Once tripped, the SFAS will automati-cally initiate containment isolation by causing the containment isolation
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Docket No. 50-346' l License No. NPF-3 Serial No. 635 July 23, 1980 valves-to close. This meets the requirements of General Design Criteria 55 & 56.
After being tripped, the blocking of the output signals will not affect the status of any device operated by the SFAS.
Indicating j
lights on the main control board provide the operator with block status of all SFAS actuated devic r as shown on the table below. Once blocked, i
devices can then only be manually moved to their non-safety mode by operating another handswitch. The block signal will remain in effect until it is manually reset or the SFAS trip is reset. The resetting of the block circuit or-the SFAS will not move any SFAS actuated device from'its safe position. As described in our response-to IE Bulletin 79-05A (Serial No. 1-56, dated Apri' 11, 1979) devices tripped by SFAS l
are blocked in small groups as identified in Fig. 7-5, A through F of i
the FSAR. No single block switch can block all SFAS devices.
The operator is fully aware of the consequences of moving a device to its non-safety mode and is responsible for returning it to its safe posi-tior, if required, on receipt of a subsequent safety actual signal.
TABT7 The status of each safety actuated devire is displayed on the main control board by Safety Actuation Monitaring (SAM) lights. The moni-toring logic for the SAM lights is as ohown '
the table below:
LIGHT CONDITION DEVICE CONDITION OFF No safety actuation demand and/or SFAS trip but device is'in non-safety actuation mode of
)
operation.
ON, DIM Safety actuation demand and device is success-fully in safety actuation mode of operation.
ON, BRIGHT Safety actuation demand but safety actuation signal is manually blocked. The device is still in the safety actuation mode of operation.
FLASHING Safety actuation demand but safety actuation signal is manually blocked. The devi c is in a Non-Safety mode of operation.
j Criterion 2:. Physical-features are provided as discussed in FSAR sec-tions 7.3.2.3 (14) and 7.3.2.3 (18) to facilitate administrative-control.
Criterion 3:
Indication is provided to show when a safety system is i
See Section 7.5.1.1 of the FSAR. Also see response to Criterion _1 above.
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Criterion 4: Diverse.and' redundant signals are provided as discussed in Sections 7.3.1.1.6 and 7.3.1.1.7 and Ta'..e 7-5 of the FSAR to have the i
SFAS initiate con *.ainment ventilation stem isolation. The signals include high containment _ radiation, lo. reactor coolant pressure and high containment pressure. Each signal will initiate isolation inde-pendent from the others.
Docket No. 50-346,
Lic nse Mo.-NPF-3 Serial No. 635 July 23, 1980' i
Criterion 5:.The SFAS and all instrumentation and control systems provided to initiate it are designed and qualified as safety grade equipment and are in compliance with IEEE 279-1971 and 323-1971 as well as other design criteria as listed in' Table 7-1 of the FSAR.
Criterion 6: As discussed in our response to IE Bulletin 80-06 (see Serial No. 1-134 dated June 13, 1980, Item 1) the blocking or resetting of the SFAS will'not cause any SFAS operated device to change position.
l ITEM 2:
In addition to responding to the general question above, please provide the following specific information:
(1) Provide an "as built" tabulation of all Engineered Safety Features (ESF)/ Auxiliary Supporting Features (ASF) valves and dampers required to be operated automatically follow-i ing an accident. This tabulation should include the folloving:
a.
Component designation b.
System served c.
Safety function (e.g., containment isolation, spray initiation) d.
Actuation signcl sources l
Reference to control circuitry (see 2(3) below) e.
f.
Indication whether or not the component safety function indicated in 2(1) above can be defeated through the use of a manual override or bypass in either the control system or actuation signal system circuitry.
Response
A tabulation of all SFAS operated devices is listed on Figure 7-5A through F of the FSAR. A detailed schematic and actuation logic is summarized in Figures 7-4 A,B of the FSAR. All SFAS operated devices can have their SFAS actuation signal blocked so that the device can be oper-l ated manually. None of the safety functions can be defeated by SFAS channel bypass capabilities.
l ITEM 2:(2) For. each manual bypass or override identified in 2(1) above, provide a description of the physical feature (s) provided to prevent inadvertent operation and to satisfy
- he requirements of IEEE Std. 279-1971, Section 4.14.
-Response:
The manual bypass feature is designe. to prevent inad-vertent operation as per the requirements of IEEE 279-1971 as discussed in FSAR Section 7.3.2.3 (14). The
. manual override feature cann( t prevent a device from moving to its safe position upon SFAS actuation. The SFAS can be overridden only by positive manual operator
. action as described in response to Criterion 1 above.
Docket-No. 50-346 License No. NPF-3 j.
Serial No. 635 July 23, 1980 ITEM 2:(3) For each actuation signal system and component actuation system identified in 2(1)d and 2(1)e above, incorporating a manual. reset, override or bypass feature, provide a complete circuit description, including detailed picto-rial information (i.e., as built circuit diagram, sche-matics, logics), sufficient to allow a thorough under-4
_ standing of the operation of such circuitry including the function and effect of all control devices (e.g., relays, contacts, switches, diodes, etc.).
Response
The block circuits and manual reset for all output mod-ules are identical and are shown on Figure 7-4A of the FSAR.
In addition, the internal circuit drawings, S9N16-1,
-2,
-3 & -4 are included in the E. I. & C.
. package which has been submittad to the NRC as an attach-ment to the FSAR. Also included in the package are all cther schematics referenced in Figure 7-5A-F of the FSAR.
s ITEM 2:(4) For each actuation signal identified in 2(1) above, identify the design standards, quality assurance require-ments, and component qualification standards involved to ensure that the systems will perform their designated safety function upon demand.
Response
For the SFAS and all related systems, refer to Table 7-1 I
of the FSAR for the applicable design criteria.
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