ML18141A512

Proposed Changes to Tech Specs Re Control Room Chlorine Detection Sys Per TMI Item III.D.3.4

ML18141A512
Person / Time
Site:	Surry
Issue date:	02/21/1984
From:	VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:
Shared Package
ML18141A511	List: ML18141A510 ML18141A512
References
RTR-NUREG-0737, RTR-NUREG-737, TASK-3.D.3.4, TASK-TM NUDOCS 8402280525
Download: ML18141A512 (8)

Text

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e ATTACHMENT l

e TS 3.7-2a G. The Main Control Room Chlorine Detection System shall be operable at all times. The number of operable channels, alarm/trip setpoint, and required operator actions shall be as specified in Table 3.7-7. This capability shall be demonstrated by the surveillance** requirements specified in Table 4.1-1.

TABLE 3. 7 -7 MAIN CONTROL ROOM CHLORINE DETECTION SYSTEM 1 2 3 4 Total No. Operator Action if Condition in of Channels Alarm/Trip Setpoint Column 2 Cannot be Met No. Functional Unit Chlorine Detector 2 s 5 ppm chlorine With one channel inoperable, re-1.

store the inoperable channel within seven days; or within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />, initiate and main-tain operation of the control room emergency ventilation sys-tem.

With two channels inoperable, within one hour initiate and maintain operation of the control room emergency ventilation sys-tem.

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monitor indication.

- e TS 3.7-9 The pressurizer safety valves utilize an acoustic monitor channel and a downstream high temperature indication channel. This capability is consistent with the recoDDD.endations of Regulatory Guide 1.97.

"Instrumentation for Light Water Cooled Nuclear Power Plants to Assess Plant Conditions During and Following an Accident". December 1975. and NUREG-0578 9 "TMI-2 Lessons Learned Task Force Status Report and Short Term Recommendations".

Control Room Chlorine Detection System The operability of the chlorine detection system ensures that sufficient capability is available to promptly detect and automatically initiate protective action in the event of an accidental chlorine release. This capability is required to protect control room personnel, and is consistent with the recommendations of Regulatory Guide 1.95, "Protection of Nuclear Power Plant Control Room Operators Against an Accidental Chlorine Release,"

February 1975.

References (1) FSAR - Section 7.5 (2) FSAR - Section 14.5 (3) FSAR - Section 14.3.2 (4) FSAR - Section 11.3.3

TABLE 4.1-1 (Continued)

Channel Description Check Calibrate Test Remarks

34. Loss of Power

a. 4.16 KV Emergency Bus N.A~ R M undervoltage (Loss of voltage)

b. 4.16 KV Emergency Bus N.A. R M undervoltage (Degraded voltage)

35. Control Room Chlorine Detectors s R M I-*

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e e ATTACHMENT 2

e e

... . . DISCUSSION OF PROPOSED CHANGE BACKGROUND NUREG-0737 Item III.D.3.4, Control Room Habitability, requires-.licensees to assure that control room operators will be adequately protected against the effects of the accidental release of toxic or radioactive gases and that the

• facility can be safely operated or shutdown under accident conditions. This

. discussion addresses toxic gas detection systems *.

Vepco has designed and installed redundant chlorine detection systems at the Surry Power Station, *units 1 and 2, which meets the requirements specified in Item III.D.3.4. Descriptions of these modifications were submitted to NRC in Vepco's response to NUREG-0737 Post-TM! Requirements, dated.December 10, 1980, as revised May 31, 1981, October Jl, 1981, and May 31, 1982.

By letter dated November 1, 1983, NRC requested licensees to submit proposed Technical Specifications for certain NUREG-0737 items, including Item

• III.D.3.4, Control Room Habitability.

EVALUATION As part of a special case study of chemical shipments along the James River submitted to NRC on June 30, 1981, Vepco agreed to make certain modifications at the Surry Power Station to meet the requirements of Item III.D.3.4. These modifications included installation of a redundant main control room bottled air bank, and installation of two independent chlorine gas detection systems at the main controi room ventilation intake.

The current main control room ventilation system consists of a normal ventilation system, an emergency ventilation system, and a single bottled dry air bank available under accident conditions to pressurize the control room to a positive differential pressure with respect to adjoining areas of the auxiliary, turbine and service buildings. A redundant bottled dry air bank has been installed and a proposed Technical Specification will be submitted seperately to reflect that addition.

Two chlorine gas detection systems, capable of detecting less than or equal to 5 ppm and automatically isolating normal control room ventilation, have also b~en installed at the main control room ventilation intake. A new proposed limiting Condition for Operation and appropriate surveillance requirements consistent with the guidance provided in the staff's November 1, 1983 Generic Letter are attached.

Pursuant to 10CFR50.59, an evaluation to determine whether an unreviewed safety question exists has been made. The proposed changes do not increase the probability of occurrence or the consequences of an accident or malfunction of equipment important to safety previously evaluated in the safety analysis

• report. The proposed change does not. af feet the probability of occurrence of an accident since it serves only as an aid to operators alerting them that a hazardous condition has already occurred, and can reduce the consequences of the accident by automatically initiating protective action in the event of an accidental chlorine release.

The proposed change does not create the possibility for an accident or malfunction of a different type than any previously evaluated in the SAR.

" e e Rather, the proposed change adds an alarm/isolation function for chlorine gas detection; this does not create any new accident type.

The proposed changes do not reduce the margin of safety as defined in the bases for any Technical Specifications. Rather, the margin _of . safety is considered increased by adding additional alarm/isolation functions to alert and protect control room operators from accidental chlorine releases. The human factors aspect of -these alarms will be considered during Vepco's control room design review as part of our response to Item I.D.l Control Room Design

- Review, of NUREG-0737.

We have also determined whether the proposed changes involve significant hazards considerations. The Commission has provided guidance concerning the application of the standards for determining whether a significant hazards consideration exists by providing certain examples (48 FR 14870). The examples of actions involving no significant hazards consideration include:

" * * * (ii) A change that constitutes an additional limitation, restriction or control not presently included in the Technical Specifications; for example, a more stringent surveillance requirement. 11 The proposed changes are encompassed by this example in that the addition of the new LCO and surveillance requirements for the chlorine detection systems constitute additional limitations not presently found in the specifications and thus are similar to the example cited above.

CONCLUSIONS Because the proposed change does not increase the probability of occurrence or the consequences of an accident or equipment malfunction, create the possibility of an accident not previously

• analyzed, nor reduce a safety margin, we conclude that no unreviewed safety question exists with respect to the proposed change.

Because the proposed change is similar to an example provided by the Commission for which no significant hazards consideration exists, we conclude that the proposed change involves no significant hazards consideration.

NO/JDH:jab/006-ml8