ML18081B276
| ML18081B276 | |
| Person / Time | |
|---|---|
| Site: | Salem  |
| Issue date: | 03/28/1980 |
| From: | Mittl R Public Service Enterprise Group |
| To: | Parr O Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8004010443 | |
| Download: ML18081B276 (8) | |
Text
{{#Wiki_filter:.. -* e 0 PS~G Public Service Electric and Gas Company 80 Park Place Newark, N.J. 07101 Phone 201/430-7000 March 28, 1980 Director of Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission Washington, D.C. 20555 Attention: Mr. Olan D. Parr, Chief Light Water Reactors Branch 3 Division of Project Management Gentlemen: ADDITIONAL INFORMATION REQUESTED CONTAINMENT PURGE AND PRESSURE-VACUUM RELIEF NO. 2 UNIT SALEM NUCLEAR GENERATING STATION DOCKET NO. 50-311 Public Service Electric and Gas Company hereby submits the following information in response to various requests from members of your staff.
- 1.
Our letter dated January 4, 1980 indicated that the Salem design will be revised to incorporate an alarm to indicate initiation of the containment purge and pressure-vacuum relief reset circuitry with an automatic actuating signal present. A copy of the attachment to this letter is enclosed (note that the response to Item 4 has been revised). Operating procedures will be revised such that these valves will not be opened in an alarm condition, and will be immediately closed if they are open upon receipt of an alarm.
- This reset alarm will be installed prior to exceeding 5% power.
- 2.
The radiation monitors that initiate containment ven-tilation isolation are also discussed in our letter dated January 4, 1980. These monitors are located outside the containment and are safety-related.
- 3.
The containment ventilation isolation circuitry hai been modified to include an additional safety injection input signal as part of the corrective action for Salem 1 License Event Report 78-61. This signal is not included in the reset circuitry. Surveillance procedures will incorporate provisions to test the operability of both safety injection inputs to the containment ventilation isolation circuitry. The Energy People A
r Director of Nuclear Reactor Regulation 3/28/80 Should you have any questions, please do not hesitate to contact us. CS02 1/2 R. L. Mittl General Manager - Licensing and Environment Engineering and Construction
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- SALEM GENERATING STATION UNITS l AND 2 RESPONSE TO NRC REQUEST FOR ADDITIONAL INFORMATION CONTAINMENT PURGE RESET CIRCUITRY ITEM l Request:
Our review indicates th~t the switch used to override the auto~atic Containment Ventilation Isolation (CVI) also defeats the manual isolation signal. It is our position that the overriding of one type of safety actuation signal should not cause the blocking of any other type of safety actuation signal to the isolation valves. Furthermore, the bypassing of manual initiation is a violation of IEEE Std. 279-1971. Therefore, justify the present design or pro-pose an alternative desigri that satisfies our concern.
Response
The purpose of the manual reset pushbutton for Containment Venti-lation Isolation at Salem is not to bypass or override an automatic protective action. The initiating circuitry for Ventilation Iso-lation e~ploys a latching element to seal in the actuating signal. Upon restoration of normal plant conditions, the latching elere~nt must be reset to regain normal operation.. The manual reset pust.- button is utilized for this purpose. The retention memory ~itt. manual reset logic is shown in Figure 1. This is a standard logic function of the Westinghouse Reactor Protection System. The retentive memory logic circuitry with manual reset allows the operator to reset the protective function even when an.actuating signal is present. This allows the operator to regain manual control to accomplish whatever recovery actions are necessary fellowing an accident. This reset to regain manual control following an accident is a required feature of the protection system. Once the protection system is reset with an actuating signal present, the retentive memory circuit blocks ariy succeeding automatic actuating signal from performing the protective function through the parti-cular device. Procedures are necessary to assure that the operator initiates a protection reset when necessary and that normal plant operations should not resume until the protection actuating signals have been cleared. Reset with an actuating signal present is acceptable when perfotming emergency operations for accident reccvery. ~*.. :. '
f - ! '!9 I . *:.. ~ ~.; . ITEM l ~esponse (C6nt'd) The Salem operating procedures have been revised to clarify the purpose of the Containment Ventilation Isolation Reset Circuitry and caution the operator about r~storing normal plant operations * . These procedures were revised as part of the corrective action for Salem Unit 1 Reportable Occurrence 78-61 and 79-11. In addition the circuit~y will be revised as described in the response to item 5 to provide an alarm whenever the reset function is initi-at*ed and an actuating signal is present. The reference to bypassing manual initiation is erroneous. As indicated in the attached logic drawing 221057-B-9545, manual initiation of ventilation isolation utilizes a separate retentive memory circuit from that of automatic actuation. A reset of the automatic actuatin~ signals with a potential block of the automatic circuit will not prevent the operator from initiating manual iso- . lation from the system level. Furthermore, a reset of the man~al circuitry does not prevent a subsequent manual initiation due to the use of momentary pushbuttons for manual actuation. In addition, the valves can be closed on an individual basis from control console pushbuttons independent of the protection system status. The opening of the valves is prevented when the protection system requires their closure. Manual initiation is not bypassed by the reset functicn and is in compliance with IEEE Standard 279-1971. . I'I:::IV: 2 Request: We require that instrumentation and controls used for the protection of public health and safety satisfy the requirements. fer reactcr protection systems. Therefore, justify the present design or pro-pose an alternative design for the radiation reonitors that initia~~ containment isolation that satisfies our requirements.
Response
~be existing radiation monitors meet the necessary protection rr-quirements for the ventilation isolation function performfd. Three radiation monitors are utilized to monitor the containment atmosphere (particulates, iodine and gaseous activity). Any of the three moni-tors will initiate isolation of the Containment Purge and Pressure-Vacuum Relief Systems. The monitors are supplied from the vital instrument buses, provided with control room indication and alarms, are testable, and included in the Technical Specifications for periodic testing and setpoints. The monitoring system has alsc b~0n seismically qualified. Environmental qualification for post accident survival is not needed. Their purpose is for normal operaticn. Th~ purge and pressure-vacuum relief isolation valves ar~ closed durinr post accident operation. Isolation is accomplished by ~afety injec-tion actuation signals. a: ~
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- 3-ITEM 3 Request:
Our revi~w also indicates that the safety injection {SI) signal can be manually reset and blocked such that a subsequent containm~nt pressure high signal or radiation high signal will not activate (VI) retenti*e memory. The staff's position in this regard is presented in request l above. J~stify your present design or modify the cir-cuitry so that appropriate safe~j~ignals will actuate CVI -whenever the protective function is required.
Response
A reset/block of the safety injection actuation signal has no effect on t~e high radiation signals utilized for containment ventilation isolation. Containment high pressure is a safety injection actua-tion signal *. An intentional block of safety injection under certain operating conditions must include containment high pressure. The ex~sting design does not.violate _any protection systere criteria. . ITE?-: 4 Reauest: We require that sufficient physical features (e.g., key lock switches) be provided to facilitate adequate administrative contrcls. Describe and justify th~ features.provided or state ycur intentions for a modified desig~.
Response
The existing containment ventilation isolation reset pushbuttons are located in the area of the console used for protection system actuation and reset functions. *The reset pushbutton is in the same control bezel on the console containing the manual actuation pushbutton for ventilation isolation. -Keylock switches/covers cannot be used and would limit operat-ing flexibility. The proper use of the pushbuttons are included in opera~ing procedures and the operator training program. As noted in the response to item 5, an alarm will be provided if the reset function is utilized with an actuating signal in existence. The operation of the reset pushbutton does not ~~.\\.l?e prob 1 ems with the safe operation of the plant. The opening of the valves with an existing actuating signal following reset caused the incident in Reportable Occurrence 78-61 and 79-11. The inclusion of the alarm plus revised. procedures is adequate to assure proper operation of the reset function
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ITEM 5 Bequest:.*., ,,I*.,..-* .< ~.., We require that system level annunciation of the override status be provided for any safety system impacted when any ov~rride is active. Your design does not satisfy this requirement. Describe and justify the features provided or state your intention for a modified design. .Response: The Salem design will be revised to include an alarm whenever the reset function is initiated with an* automatic actuating signal present. The operator will be instructed to not open the purge and/or pressure-vacuum relief valves or immediately close the valves if open upon alarm ~ondition. Normal operation of the systems will only proceed upon clearing of the actuating signals
- ITEM 6 Request:
The Salem plants will monitor (1). the containment atmosphere and (2) the plant stack, for airborne particle iodine and gas activity. In that these two sets of radiation monitors are not fully redun-dant backups to each other, we consider each set to be a different source of a required isolation actuation signal *. We require t~at, shoul~ one safety actuation signal be overriden, the other radiation monitoring system should be capable of actuating containment iscla-tion and alerting the operators to the cause of isolation when a trip level is reached. Describe and justify the features provided or state your intention for a modified design.
Response
Please refer to the above responses. With the institution of tte revised operating procedures and reset alarm, the proper cperaticn of the reset function will be performed by the operators. The blocking of actuation signals when required for ventilation isola-tion should not occur.
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