ML18032A344

Proposed Tech Specs,Clarifying Trip Level Setting in Table 3.2.A for Standby Gas Treatment Sys Relative Humidity Heater

ML18032A344
Person / Time
Site:	Browns Ferry, Oconee
Issue date:	05/29/1987
From:	TENNESSEE VALLEY AUTHORITY
To:
Shared Package
ML18032A343	List: ML18032A342 ML18032A344
References
TAC-R00031, TAC-R00032, TAC-R00033, TAC-R31, TAC-R32, TAC-R33, NUDOCS 8706100333
Download: ML18032A344 (8)

Text

ENCLOSURE 1 PROPOSED TECHNICAL SPECIFICATIONS REVISIONS BROWNS FERRY NUCLEAR PLANT UNITS 1, 2, AND 3 (TVA BFN TS 232) 8706100333 8705>~

PDR ADOCK 05000259 p PDR

TABLE 3.2.A (Continued)

PRIMARY CONTAINMENT ANO REACTOR BUILDING ISOLATION INSTRUMENTATION Minimxn No.

Instrument Channels Operable er Tri S s 1 ll Function Tri Level Settin Action 1 Remarks Instrument Channel < 100 mr/hr or downscale F 1. 1 upscale or 2 downscale will Reactor Building a. Initiate SGTS Ventilation High b. Isolate refueling floor Radiation Refueling Zone c. Close atmosphere control system.

2(T) (8) Instrunent Channel >2000 cfm and < 4000 cfm H and Below trip setting, R. H.

SGTS Flow - Train A (A or F) heaters will shut off.

R. H. Heaters 2(T) (8) Instrenent Channel >2000 cfm and < 4000 cfm H and Below trip setting, R. H.

SGTS Flow Train B (A or F) heaters will shut off.

R. H. Heaters 2(l) (8) Instrument Channel >2000 cfm and < 4000 cfm H and Below trip setting, R. H.

SGTS Flow Train C (A or F) heaters will shut off.

R. H. Heaters Reactor Building Isolation 0 < t<2 secs. HorF l. Below trip setting prevents Timer (refueling floor) spurious trips and system perturbations fran initiating isolation.

Reactor Building Isolation 0 < t<2 secs. Gor A 1. Below trip setting prevents Timer (reactor zone) or H spurious trips and system perturbations from initiating isolation.

2(10) Group 1 (Initiating) Logic N/A 1 Refer to Table 3.7.A for list of valves.

BFN Unit 1

TABLE 3.2.A (Continued)

PRINRY CONTAINNENT AND REACTOR BUILDING ISOLATION INSTRUHENTATION Hinimm No.

Instrwent Channel s Operable Function Tri Level Settin Action 1 Remarks Instrument Channel < 100 mr/hr or downscale F 1. 1 upscale or 2 downscale will Reactor Building a. Initiate SGTS Ventilation High b. Isolate refueling floors Radiation Refueling Zone c. Close atmosphere control system.

2(7) (8) Instrument Channel >2000 cfm and < 4000 cfm H and Below trip setting, R. H.

SGTS Flow Train A (A or F) heaters w>11 shut off.

R. H. Heaters 2(7) (8) Instrunent Channel >2000 cfm and < 4000 cfm H and Below trip setting, R. H.

SGTS Flow Train B 4 (A or F) heaters w) ll shut off.

R. H. Heaters 2(7) (8) Instrwent Channel >2000 cfm and < 4000 cfm H and Below trip setting, R. H.

SGTS Flow Train C (A or F) heaters wi 11 shut off.

R. H. Heaters Reactor Building Isolation 0 < t<2 secs. HorF 1. Below trip setting prevents Timer (refueling floor) spurious trips and system perturbations frcm initiating isolation.

Reactor, Building Isolation 0 < t<2 secs. G or A 1 Below trip setting prevents Timer (reactor zone) or H spurious trips and system perturbat>ons frcm >n>t>at>ng isolation.

2(10) Group 1 (Initiating) Logic N/A 1. Refer to Table 3.7.A for list of valves.

BFN Unit 2

TABLE 3.2.A (Continued)

PRINARY CONTAINNENT AND REACTOR BUILDING ISOLATION INSTRUNENTATION Hiniaxm No.

Instrument Channels Operable Function Tri Level Settin Action 1 Remarks Instrunent Channel < 100 mr/hr or downscale F 1. 1 upscale or 2 downscale will Reactor Building a. Initiate SGTS Ventilation High b. Isolate refueling floor.

Radiation Refueling Zone c. Close atmosphere control system.

2(7) (8) Instrument Channel >2000 cfm and < 4000 cfm H and Below trip setting, R. H.

SGTS Flow Train A (A or F) heaters w> 11 shut off.

R. H. Heaters 2(7) (8) Instrument Channel >2000 cfm and < 4000 cfm H and Below we'llsetting, trip R. H.

SGTS Flow Train 8 (A or F) heaters w ll shut off.

R. H. Heaters 2(7) (8) Instrument Channel >2000 cfm and < 4000 cfm H and Below trip setting, R. H.

SGTS Flow Train C (A or F) heaters shut off.

R. H. Heaters Reactor Building Isolation 0 < t<2 secs. HorF 1. Below trip setting prevents Timer (refueling floor) spurious trips and system perturbations frcm initiating isolation.

Reactor Building Isolation 0 < t<2 secs. G or A 1. Below trip setting prevents Timer (reactor zone) or H spurious trips and system perturbations fran initiating isolation.

2(10) Group 1 (Initiating) Logic N/A 1 Refer to Table 3 7 A for list of valves.

BFN Unit 3

ENCLOSURE 2 DESCRIPTION AND JUSTIFICATION BROGANS FERRY NUCLEAR PLANT Descri tion of Chan e The Browns Ferry Nuclear Plant (BFN) Units 1, 2, and 3 Technical Specifications, table 3.2.A, page 3.2/4.2-9, is revised to clarify the trip level setting for the Standby Gas Treatment System (SGTS) relative humidity heater. The current requirement of "less than or equal to 2000 cfm" is changed to be "greater than or equal to 2000 cfm and less than or equal to 4000 cfm".

Reason for Chan e An ambiguity exists between the trip level setting column and the remarks column of table 3.2.A. The trip level set,ting requirement is less than or equal to 2000 cfm which would require the actual trip point to be below 2000 cfm. The remarks require the heater to be shut off below 2000 cfm and, therefore, require an actual trip point above 2000 cfm.

Justification for Chan e The SGTS provides a means for minimizing the release of radioactive material from the containment to the environs by filtering and exhausting the air from any or all zones of the Reactor Building and maintaining, the building at a negative pressure (such that air leakage is into, not out of, the building) during containment isolation conditions. The SGTS consists of three blower/filter trains which can take suction from any or all of the three reactor zone or refueling zone secondary containments. Each train is equipped with a 40-kw electric heater which'is designed to reduce the relative humidity of the inlet air to less than 70 percent relative humidity. The heater is energized automatically with the startup of the SGTS train and remains energized until the blower is stopped. The heater is interlocked with the airflow to prevent burnout of the elements with low airflow. A temperature sensor close to the heater also trips the heater if the temperature exceeds 180 F. The interlock with airflow is provided by redundant flow switches designed to operate at <50 percent of normal flow as stated in Final Safety Analysis Report (FSAR), section 5.3.3 from the blowers so that when the blower

'. In addition, th'e heaters are wired shuts down or loses power, the heater is deenergized.

The intent of the technical specification requirement in table 3.2.A for the relative humidity heater switch is to turn of;" the heater before a decreasing SGTS flow reaches 2,000 cfm. This would prevent damage to the SGTS filter banks by turning, off the heater before reaching a flow that would not adequately transfer the heat. A literal reading of the current technical specification wording would allow a setpoint of 0 cfm which does not fulfill the intent of the technical specifications. Therefore, the "less than or equal to" requirement should be changed to "greater than or equal to" in order to meet the intent of the technical specifications and achieve agreement with the design basis.

Justification for Chan e (Cont'd)

An upper bound of 4,000 cfm is imposed on the setpoint to ensure that the flow switches do not prevent the heaters from performing their function during normal blower operation. Technical specification 3.7.B.2.c requires that each train operate within + 10 percent of design flow (9,000 cfm). Therefore, when the system is initiated, the airflow for an operable train will be greater than 4,000 cfm and the heaters will perform their function.

The proposed change makes the technical specifications more consistent with the design basis and the FSAR and, therefore, will increase the margin of safety.

ENCLOSURE 3 DETERMINATION OF NO SIGNIFICANT HAZARDS CONSIDERATION BROWNS FERRY NUCLEAR PLANT (BFN) UNITS 1, 2, AND 3 Descri tion of Amendment The proposed amendment would modify the Browns Ferry Nuclear Plant Technical Specification fox units 1, 2, and 3 to clarify the trip level setting in Table.

3.2.A for the Standby Gas Treatment System (SGTS) relative humidity heaters.

The current setting is less than ox'qual to'2,000 cfm but a note to the table implies a setting above 2,000 cfm. The proposed amendment would revise the setting to be between 2,000 and 4,000 cfm.

Basis for Pro osed No Si nificant Hazards Consideration Determination NRC has provided standards for determining whether a significant hazards consideration exists as stated in 10 CFR 50.92 (c). A proposed amendment to an operating license for a facility involves no significant hazards consideration if operation of the facility in accoxdance with a proposed amendment would not (1) involve a significant increase in the probability or consequences of an accident previously evaluated, or (2) create the possibility of a new or different kind of accident from any accident previously evaluated, ox (3) involve a significant reduction in a margin of safety.

1. The probability or consequences of a previously evaluated accident will not be significantly increased since the proposed amendment will provide consistency and clarification of table 3.2.A requirements and notes for the relative humidity heater shutoff setpoints without altering the funcLion. -Furthermore, the direction of the setpoint movement is conservative in respect to the switch function which is turning off the heaters before reaching a flow that would not adequately transfer the heat.

2. The possibility of a new or different kind of accident is not created since this'hange will not eliminate any protective functions and the setpoint change is in a conservative direction. Also, no new operational conditions will be permitted.

3. The proposed change will not involve a significant reduction in any margin of safety since the setpoint change is conservative and no functions or equipment changes are involved.

Si;:ce the application for amendment involves a proposed change that is encompassed by the criteria for which no significant hazards consideration exists, TVA proposes to determine that the proposed amendment does not involve a significant hazards consideration.