ML17332A810
| ML17332A810 | |
| Person / Time | |
|---|---|
| Site: | Cook  |
| Issue date: | 06/08/1995 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML17332A809 | List: |
| References | |
| NUDOCS 9506280673 | |
| Download: ML17332A810 (4) | |
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UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO A COMMITMENT TO INSTALL FIRE ALARM REFLASH DONALD C.
COOK NUCLEAR PLANT UNITS 1
AND 2 DOCKET NOS. 50-315 AND 50-316
1.0 INTRODUCTION
By letter dated August 24,
- Company, the licensee for Donald C.
Cook Nuclear Plant, Units 1 and 2 (Cook), withdrew a commitment to install fire alarm system reflash capability in the control room.
2.0 DISCUSSION On November 1st and 2nd,
- 1989, the U.S. Nuclear Regulatory Commission staff (the staff) met with the licensee at the Cook site to discuss post-fire safe shutdown methodology issues at Cook, In the context of discussions regarding circuit supervision, the staff asked if the alarm system at Cook had the capability to reflash.
The licensee responded
- that, although this capability did not exist at the time, the reflash capability would be installed on the fire protection alarm system in the control room by December 1991.
The licensee documented this verbal commitment in a letter of February 21, 1990.
By letter of December 2,
- 1991, the licensee changed the target date from December 1991 to December 31, 1994.
By letter of August 24,
- 1994, the licensee stated that it had cancelled its plans to install reflash capability on the fire protection alarm system in the control room.
During the November 1989 meeting, the licensee also responded to the staff concerns that all fire alarm system circuits were not electrically supervised in accordance with the requirements of National Fire Protection Association Standard 72D (NFPA 72D), "Standard for the Installation, Maintenance and Use of Proprietary Protective Signaling Systems."
The staff documented this discussion with the licensee in its Safety Evaluation Report (SER) of April 26, 1990.
The SER states that all fire alarm system circuits at Cook were supervised in accordance with NFPA 72D with the exception of two circuits within the control room.
Based on this statement and on the licensee commitment to install a reflash capability on the fire detection alarm system, the staff concluded in its SER of April 26, 1990, that the issue of fire alarm system circuit supervision was resolved.
However, in a letter of December 2,
- 1991, the licensee stated that there are more than two
~ unsupervised fire alarm system circuits at Cook.
In the light of this new information regarding system supervision and of the licensee's plans not to install reflash capability in the control room, the staff has reviewed the fire alarm system circuit supervision at Cook.
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3.0 EVALUATION Section E. 1.(a) of Appendix A to Branch Technical Position (BTP) Auxiliary Power Conversion Systems Branch (APCSB) 9.5-1 states that fire detection systems
- should, as a minimum, comply with NFPA 72D and that deviations be identified and justified.
NFPA 72D specifies that fire alarm circuits be electrically supervised as defined below.
However, neither BTP APCSB 9.5-1 nor NFPA 72D specify a need to install fire alarm system reflash capability.
The American National Standards Institute defines "reflash" as an auxiliary logic circuit that allows two or more abnormal process conditions to initiate or reinitiate the alarm state of on'e alarm point at any time.
The alarm point cannot return to normal until all related process conditions return to normal.
A proprietary signaling
- system, as defined by NFPA 72D, transmits detection and suppression system actuation signal to a central supervisory station where operators take the necessary actions.
The purpose of electric circuit supervision of a system is to detect circuit breaks, ground faults, removal of a detection device from a detector circuit, and power failure. If any of these problems
- occur, system trouble is annunciated at the local and central control panels.
In a letter of December 2,
- 1991, the licensee stated that the following fire protection system signals were not fully supervised as specified in NFPA 72D:
The CO< system Cardox and Alison control panel alarm and trouble signals.
The reactor coolant pump (RCP) panel alarm and trouble signals.
The containment cable tray detection panel alarm and trouble signals.
The Halon system Alison and Pyrotronics control panel alarm and trouble signals.
The alarm initiating circuits for water flow.
The sprinkler supervisory (valve tamper and low air pressure switches)
- signals, and The fire pump signals.
The licensee indicated that any abnormal condition on one of these systems is transmitted to the annunciator logic cabinet, a local panel located within the control room boundary behind the main control board.
The alarm and trouble signals are then transmitted to the front of the control board by electrical circuits.
The circuits between the end of line devices and the local control panels are supervised for ground fault and circuit break in accordance with NFPA 72D.
The circuits between the local control panels and the logic cabinets are supervised for ground fault only, and therefore are not supervised in accordance with NFPA 72D.
The licensee identified the deviations from NFPA 72D and provided justifications for these deviations in Attachment 3 of its December 2,
1991, letter.
The staff has reviewed the justifications for the deviations from the requirements of NFPA 72D for these systems as provided by the licensee.
Inoperability of these systems during a fire would not prevent the fire suppression systems from actuating because system operation is independent of the panels located in the control room.
An audible signal at the local control panel would alert plant personnel of the abnormal condition.
The alarm would alert the operators to investigate the trouble signal in accordance with plant procedures, repair the system or establish compensatory measures in the affected area in accordance with the plant technical specifications.
In addition, the licensee verifies operability of the circuits during the performance of its respective surveillances and each local panel is checked at least once per shift.
These checks provide reasonable assurances that system malfunctions will be promptly found.
On these
- bases, the staff concludes that the deviations from the staff guidance of Section E.I.(a) of Appendix A to BTP APCSB 9.5-1 and from NFPA 72D for these systems are acceptable.
4.0 CONCLUSION
On the basis of its evaluation, the staff concluded that the licensee's decision to withdraw its commitment to install detection system reflash capability in the control room is acceptable.
Principal Contributor:
D. Oudinot Date:
June 8, 1995
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