ML20235B009

Proposed Tech Specs Re Trip Setpoints & Operating Requirements

ML20235B009
Person / Time
Site:	Fort Saint Vrain
Issue date:	08/28/1987
From:	PUBLIC SERVICE CO. OF COLORADO
To:
Shared Package
ML20235B002	List: ML20235A997 ML20235B009
References
TAC-47416, NUDOCS 8709230496
Download: ML20235B009 (38)

Text

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Fort St. Vrain #1:

Technical Specifications

. Amendment #

Page 3.3-1 I

.1 3.3 LIMITING SAFETY 1(STEM SETTINGS Applicability Applies to the trip settings for. instruments and devices which provide for monitoring of reactor power, hot reheat i temperature, reactor internal pressure, and moisture content of  !

.the hel'im coolant.

Objective To provide for automatic protective action such that the principal process variables do not exceed a safety limit as a result of transients.

Specification LSSS 3.3 - Limitino Safety System Settings The Limiting Safety System Settings for trip shall be as

.specified in Table 3.3.1. The following definitions are used in the table:

. Trip Setpoint - The trip setpoint is the least conservative' "as left" value for a channel to be considered Operable.  !

. Allowable Value - The allowable value is the lea't - s conservative "as found" value for a channel to be considered Operable. 1 i

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Fort St. Vrain 01 Technical Specifications l Amendment 0 Page 3.3-2a

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Specification LSSS 3.3 Table 3.3-1 i

LIMITING SAFETY SYSTEM SETTINGS TRIP ALLOWABLE PARAMETER FUNCTION SETPOINT VALUE

1. Reactor Core Limiting Safety System Settings a) Linear Scram Varies as a Varies as a Channel-High Function of Function of (Neutron Indicated Indicated Flux) Thermal Thermal Power per Power per Figure 3.3-1 Figure 3.3-1 b) Reheat Scram $ 1055 5 1067 Steam degree F degree F Temperature-High c) Primary Scram 5 68.6 psi 5 72.7 psi )

Coolant below normal, below normal, Pressure- programmed programmed Programmed with Circu- with Circu-Low lator. Inlet lator Inlet Temperature. Temperature Upper TRIP per Figure SETPOINT of 3.3-2. Upper

> 631.1 psia. limit to produce trip at > 627 psia.

Fort St. Vrain 01 Technical Specifications Amendment 0 Page 3.3-2b I

Specification LSSS 3.3  !

Table 3.3-1 (Continued)

LIMITING SAFETY SYSTEM SETTINGS TRIP ALLOWABLE PARAMETER FUNCTION SETPOINT VALUE

2. Reactor Vessel Pressure Limiting Safety System.

Settings a) Primary Scram and 5 46 psi 5 52.7 psi Coolant Preselected above normal, above normal, Pressure- Loop Shutdown programmed programmed Programmed and Steam / with Circu- with Circu-High Water Dump lator Inlet lator Inlet Temperature. Temperature Upper TRIP per Figure SETPOINT of 3.3-2. Upper 5 746.3 psia. limit to Lower TRIP produce trip SETPOINT of at < 753 5 538.3 psia, psia. Lower limit to produce trip at 1 545 psia b) Primary Scram, Loop 5 60.5 5 62.2 Coolant Shutdown, degree F degree F Moisture- and Steam / dewpoint dewpoint High Water Dump temperature temperature c) PCRV Pressure Pressure: Relief Rupture Disc 812 psig plus 820 psig (Low Set or minus 8 Safety Valve) psi I

Fort St. Vrain #1 i Technical. Specifications Amendment # {

j Page 3.3-2c l i

Specification LSSS 3,3 '

)'

Table 3.3-1 (Continued)

LIMITING SAFETY SYSTEM SETTINGS TRIP ALLOWABLE PARAMETER FUNCTIDN SETp0 INT VALUE Low Set Safety 796 psig plus 804 psig Valve or minus 8 psi Rupture Disc 832 psig plus 840 psig (High Set Safety or minus 8 psi Valve)

High Set Safety 812 psig plus 820 psig Valve or minus 8 psi '

d) Helium Pressure Circulator Relief Penetration Interspace Pressure:

Rupture Disc 825 psig plus 842 psig (2 Per or minus 17 Penetration) psi Safety Valve 805 psig plus 829 psig 1 (2 Per or minus 24 1 Penetration) psi i e) Steam Pressure Generator Relief Penetration Interspace Pressure:

Rupture Disc 825 psig ;1us 842 psig (2 For Each or minus 17 Steam Generator) psi Safety Valve 475 psig plus 489 psig (2 For Each or minus 14 Steam Generator) psi

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-Low

9. Main Steam Pressure-Low > 1529 psig

>1517 psig

10. Plant Electrical System-Loss > 278V > 266V 331.5 Seconds 335 Seconds

11. Two Loop Trouble Not Applicable Not Applicable

12. High Reactor Building 5 161 degree F $ 166 degree F Temperature (Pipe Cavity)

Notes for Tables 4.4-1 through 4.4-4 are on Pages 4.4-8 and 4.4-9

r Fort St. Vrain 01 Technical Specifications Amendment #

Page 4.4-3c l

l l SPECIFICATION LCO 4.4.1

j. TABLE 4.4-1 (Part 2)

INSTRUMENT OPERATING REQUIREMENTS FOR PLANT PROTECTIVE SYSTEM, SCRAM MINIMUM MINIMUM PERMISSIBLE OPERABLE DEGREE OF BYPASS NO. FUNCTIONAL UNIT CHANNELS REDUNDANCY CONDITIONS la. Manual (Control Room) 1 0 Nne Ib. Manual (Outside Control 2 (f) 1 None Room)

2. Startup Channel-High 2 1 Reactor Mode Switch in "RUN" 3a. Linear Channel-High, 2 (f) 1 None Channels 3, 4, 5 3b. Linear Channel-High, 2 (f) 1 None Channels 6, 7, 8

4. Primary Coolant Moisture High Level Monitor 1 (f,t) 1(c) (h2)

Loop Monitor 2/ Loop (f,t) 1/ Loop (hl)

5. Reheat Steam 2 (b,f) 1 None Temperature - High

6. Primary Coolant 2 (f.k) 1 Less Than 30%

Pressure - Rated Power Programmed Low

7. Primary Coolant 2 ( f,'k) 1 None Pressure -

Programmed High

8. Hot Reheat Header 2 (f) 1 Less Than 30%

Pressure - Low Rated Power

9. Main Steam 2 (f) 1 Less Than 30%

Pressure - Low Rated Power

10. Plant Electrical 2 (e.f) 1 None System - Loss

11. Two Loop Trouble 2 1 Reactor Mode Switch in

" Fuel Loading"

12. High Reactor Building 2 (f) 1 None Temperature (Pipe Cavity)

Notes for Tables 4.4-1 through 4.4-4 are on Pages 4.4-8 and 4.4-9 w__-___ _

Fort St. Vrain 01 Technical Specifications Amendment #

Page 4.4-4a Specification LC0 4.4.1 Table 4.4-2 (part 1)

INSTRUMENT OPERATING REQUIREMENTS FOR THE PLANT PROTECTIVE SYSTEM. LOOP SHUTDOWN TRIP ALLOWABLE NO. FUNCTIONAL UNIT SETPOINT VALUE la. Deleted Ib. Deleted Ic. Deleted Id. Deleted le. Deleted If. Deleted 2a. Deleted 2b. Deleted 2c. Deleted 2d. Deleted 3a. Loop 1 Shutdown Logic Not Applicable Not Applicable 3b. Loop 2 Shutdown Logic Not Applicable Not Applicable 4a. Circulator 1A and IB Not Applicable Not Applicable Shutdown - Loop Shutdown Logic Notes for Tables 4.4-1 through 4.4-4 are on Pages 4.4-8 and 4.4-9

Fort St. Vrain #1 -

Technical Specifications Amendment #

Page 4.4-4b l Specification LCO 4.4.1 l Table 4.4-2 (Part 1) {

l INSTRUMENT OPERATING REQUIREMENTS l FOR THE PLANT PROTECTIVE SYSTEM, LOOP SHUTDOWN l TRIP ALLOWABLE l NO. FUNCTIONAL UNIT SETPOINT VALUE l 4b. Circulator 1C and 10 Not Applicable Not Applicable l Shutdown - Loop l Shutdown Logic -

l l Sa. Steam Generator 5 796 psig 5 801 psig l Penetration l Overpressure, Loop 1 l Sb. Steam Generator 5 796 psig $ 801 psig l Penetration l Overpressure, Loop 2 1 6a. High Reheat Header 5 3.2 mrem /hr 5 3.5 mrem /hr ,

l Activity, Loop 1 Above Above l Backgrour.d Background l 6b. High Reheat Header 5 3.2 mrem /hr 5 3.5 mrem /hr ,

l Activity, Loop 2 Above Above l Background Background l l 7a. Low Superheat Header 3 798 degree F 3 794 degree F 1

i Temperature, Loop 1 l 7b. Low Superheat Header 3 798 degree F 3 794 degree F l Temperature, Loop 2 l 7c. High Differential 1 44.8 degree F $ 46.7 degree F l Temperature Between l Loop 1 and Loop 2 I.

l Notes for Tables 4.4-1 through 4.4-4 are on Pages 4.4-8 and 4.4-9

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Fort St. Vrain #1 Technical Specifications Amendment #

Page 4.4-4c

, SPECIFICATION LCO 4.4.1 TABLE 4.4-2 (Part 2)

INSTRUMENT OPERATING REQUIREMENTS FOR PLANT PROTECTIVE SYSTEM, LOOP SHUTDOWN MINIMUM MINIMUM PERMISSIBLE OPERABLE DEGREE OF BYPASS NO. FUNCTIONAL UNIT CHANNELS REDUNDANCY CONDITIONS la. Deleted Ib. Deleted Ic. Deleted Id. Deleted le. Deleted If. Deleted 2a. Deleted 2b. Deleted 2c. Deleted 2d. Deleted 3a. Loop 1 Shutdown 2 1 None Logic 3b. Loop 2 Shutdown 2 1 None Logic Notes for Tables 4.4-1 through 4.4-4 are on Pages 4.4-8 and 4.4-9

Fort St. Vrain #1 Techt.f cal Specifications Amendment #

Page 4.4-4d SPECIFICATION LCO 4.4.1 TABLE 4.4-2 (Part 2)

INSTRUMENT OPERATING REQUIREMENTS FOR PLANT PROTECTIVE SYSTEM, LOOP SHUTDOWN MINIMUM MINIMUM PERMISSIBLE OPERABLE DEGREE OF BYPASS NO. FUNCTIONAL UNIT CHANNELS REDUNDANCY CONDITIONS 4a. Circulator IA and IB 2 1 None Shutdown - Loop Shutdown Logic 4b. Circulator 1C and ID 2 1 None Shutdown - Loop Shutdown Logic Sa. Steam Generator 2 (f) 1 None Penetration Overpressure, Loop 1 Sb. Steam Generator 2 (f) 1 None Penetration Overpressure, Loop 2 6a. High Reheat Header 2(f) 1 None Activity, Loop 1 6b. High Reheat Header 2 (f) 1 None Activity, Loop 2 7a. Low Superheat Header 2 (f) 1 Less Than 30%

Temperature, Loop 1 (p) Rated Power 7b. Low Superheat Header 2 (f) 1 Less Than 30%

Temperature, Loop 2 (p) Rated Power I

7c. High Differential 2 (f) 1 Less Than 30% l Temperature Between Rated Power  !

Loop 1 and Loop 2 (p) l l

I Notes for Tables 4.4-1 through 4.4-4 are on Pages 4,4-8 and 4.4-9 l

Fort St. Vrain 01 Technical Specifications Amendment #

Page 4.4-5a Specification LCO 4.4.1 Table 4.4-3 (Part 1)

INSTRUMENT OPERATING REQUIREMENTS FOR THE PLANT PROTECTIVE SYSTEM, CIRCULATOR TRIP TRIP ALLOWABLE NO. FUNCTIONAL UNIT SETPOINT VALUE

1. Circulator Speed 5 1850 rpm Below 5 2035 rpm Below

- Low Normal As Normal As Programmed by Programmed by  !

Feedwater Flow Feedwater Flow 2a. Loop 1, Fixed > 230,500 lb/hr > 230,500 lb/hr Feedwater {20% of normal {20%ofnormal Flow - Low (Both Full Load) Full Load)

Circulators) 2b. Loop 2, Fixed > 230,500 lb/hr > 230,500 lb/hr Feedwater T20% of normal {20%ofnormal Flow - Low (Both Full Load) Full Load)

Circulators)

3. Loss of Circulator 1 459 psid 3 454 psid Bearing Water 4 Circulator 5 796 psig 5 801 psig Penetration Trouble

5. Circulator Drain 1 8.5 psid 3 8.0 psid Malfunction

6. Circulator Speed - 5 11,495 rpm 5 11,684 rpm High Steam

7. Manual Not Not Applicable Applicable Notes for Tables 4.4-1 through 4.4-4 are on Pages 4.4-8 and 4.4-9

Fort St. Vrain 01 Technical Specifications Amendment t Page 4.4-5b-Sp_ edification LC0 4.4.1 Table 4.4-3 (Part 1)

INSTRUMENT OPERATING REQUIREMENTS FOR THE PLANT PROTECTIVE SYSTEM, CIRCULATOR TRIP TRIP ALLOWABLE NO. FUNCTIONAL LiNIT SETPOINT VALUE

8. Circulator Seal > -5.2" H20, > -6.1" H20, Malfunction 3+74.8"H2O 3+76.1"H2O

9. Circulator Speed - 5 8,589 rpm 5 8,786 rpm High Water l

i Notes for Tables 4.4-1 through 4.4-4 are on Pages 4.4-8 and 4,4-9

Fort St'. Vrain.#1-Technical Specifications-Amendment #

Page 4.4-5c SPECIFICATION LCO 4.4.1-TABLE 4.4-3 (Part 2)

INSTRUMENT OPERATING REQUIREMENTS FOR PLANT PROTECTIVE SYSTEM.

CIRCULATOR TRIP MINIMUM MINIMUM PERMISSIBLE 0PERABLE DEGREE OF. BYPASS NO. FUNCTIONAL UNIT CHANNELS ' REDUNDANCY CONDITIONS

1. Circulator Speed 2 (f) 1 Less Than 30%

- Low (r)

Rated Power 2a. Loop 1, Fixed Feed- 2 (f) 1 Less Than 30%

water Flow - Low Rated Power (BothCirculators) 2b. Loop 2, Fixed Feed- 2 (f) 1 Less Than 30%

water Flow - Low Rated Power.

(Both Circulators)

3. Loss of Circulator 2 (f)- 1 None Bearing Water (r)'

4. Circulator 2 (f) 1 None Penetration

-Trouble (r)

5. Circulator Drain 2 (f) 1 None Malfunction (r)

6. Circulator Speed - 2 (f) 1 None

-High Steam (r)

7. ~ Manual- 1 0 None

8. Circulator Seal 2 (f) 1 Opposite loop Malfunction (r) shutdown fo circulator seal

' malfunction trip of other circulator in same loop

9. Circulator Speed - 2 (f) 1 None High Water Notes for Tables 4.4-1 through 4.4-4 are on Pages 4.4-8 and 4.4-9 k

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Fort St. Vrain #1 l Technical Specifications Amendment #

Page 4.4- 7a I

Specification LC0 4.4.1 Table 4.4-4 (Part 1)

INSTRUMENT OPERATING REQUIREMENTS FOR THE PLANT PROTECTIVE SYSTEM, R00 WITHDRAWAL PROHlBIT (RWP)

TRIP ALLOWABLE NO. FUNCTIONAL UNIT SETPOINT VALUE

1. Startup Channel-Low 3 4.2 cps 3 3.2 cps Count Rate 2a. Linear Channel-Low ~< 5% (m) ~< 5%

Power RWP (Channels 3, 4 and 5) 2b. Linear Channel-Low ~< 5% (m) ~< 5%

Power RWP (Channels 6, 7 and 8) 3a. Linear Channel-High -< 30*;(n) ~< 30%

Power RWP (Channels 3, 4 and 5) 3b. Linear Channel-High ~< 30*;(n) < 30%

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Power RWP (Channels 6, 7 and 8)

Notes for Tables 4.4-1 through 4.4-4 are on Pages 4.4-8 and 4 4-9

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Fort St. Vrain #1 Technical Specifications ,

Amendment #

Page 4.4-7b 1 l

SPECIFICATION LCO 4.4.1 L

TABLE 4.4-4 (Part 2)

INSTRUMENT OPERAT7"G REQUIREMENTS FOR REACTOR PIiOTECTIVE SYSTEM, f00 WITH0RAWAL PROHIBIT (RWP)

MINIMUM MINIM'JM PERMISSIBLE OPERABLE DEGREE OF BYPASS NO. FUNCTIONAL UNIT CHANNELS REDUNDANCY CONDITIONS

1. Startup Channel - Low 2 1 Above 1.0E-03%

Count Rate Rated Power 2a. Linear Channel - Low 2 1 (g)

Power RWP (Channels 3, 4, and 5) 2b. Linear Channel - Low 2 1 (g)

Power RWP (Channels 6, 7, and 8) 3a. Linear Channel - High 2 (f) 1 Above 30%

Power RWP (Channels 3, Rated Power 4, and 5) 3b. Linear Channel - High 2 (f) 1 Above 30%

Power RWP (Channels 6 Rated Power 7, and 8)

Notes for Tables 4.4-1 through 4.4-4 are on Pages 4.4-8 and 4.4-9 l

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I Fort St. Vrain #1 Technical Specifications Amendment #

l Page 4.4 l SPECIFICATION LC0 4.4.1 NOTES FOR TABLES 4.4-1 THROUGH 4.4-4 l l a) Deleted, b) Two thermocouple from each loop, total of four, constitute I one channel. For each channel, two thermocouple must be operable in at least one operating loop for that channel to be considered operable.

c) With one primary coolant high level moisture monitor tripped, trips of either loop primary coolant moisture monitors will cause full scram. Hence, number of operable channels (1) minus minimum number required to cause scram (0) equals one, the '

minimum degree of redundancy, d) Deleted, e) One channel consists of three undervoltage relays each monitoring a single phase of a 480 VAC essential bus. A channel trip will occur when two of the three undervoltage relays comprising that channel operate after a preset time delay indicating loss of bus voltage. Initiation of a scram requires two of the three undervoltage relays on two of the three 480 VAC essential buses to operate.

f) The inoperable channel must be in the tripped condition, unless the trip of the channel will cause the protective action to occur. Failure to trip the inoperable channel requires taking the appropriate corrective action as listed on Pages 4.4-1 and 4.4-2 within the specified time limit. ,

g) RWP bypass permitted if the bypass also causes associated single channel scram, hl) For loop monitors only, permissible bypass conditions include:

I. Any circulator buffer seal malfunction.

II. Loop hot reheat header high activity.

III. As stated in LC0 4.9.2.

h2) For high level monitors only, permissible bypass conditions include:

1. As stated in LCO 4.9.2.

j) Deleted, k) One operable helium circulator inlet thermocouple in an operable loop is required for the channel to be considered operable.

m) Low Power RWP bistable resets at 4?; after reactor power initially exceeds 5?;.

n) Power range RWP bistables automatically reset at 10?; after reactor power is decreased from greater than 30?;. The RWP may be manually reset betwaen 10?e and 30?; power.

p) Item 7a must be accompanied by item 7c. for Loop 1 shutdown.

Item 7b. must be accompanied by item 7c. for Loop 2 shutdown.

Fort St. Vrain #1

. Technical Specifications Amendment #

Page 4.4-10 1

Basis for Specification LCO 4.4.1 i The plant protection system automatically initiates protective functions to prevent established limits from being exceeded. In addition, other protective instrumentation is provided to initiate action which mitigates the consequences of accidents. This specification provides the limiting conditions for operation necessary to preserve the effectiveness of these instrument systems.

If the minimum operable channels or the minimum degrees of redundancy for each functional unit of a table cannot be met or cannot be bypassed under the stated permissible bypass conditions, the following action shall be taken:

For Table 4.4-1, the reactor shall be shut down within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.

For Table 4.4-2, the affected loop shall be shut down within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.

For Table 4.4-3, perform one of the following within 12 hour1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />s:

1) The reactor shall be shutdown, or

2) the affected helium circulator shall be shutdown.

For Table 4.4-4, the reactor shall be shut down within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

If, within the indicated time limit, the minimum number of operable channels and the minimum degree of redundancy can be reestablished, the system is considered {

normal and no further action needs to be taken.

The trip level settings are included in this section of the specification. The bases for these settings are briefly discussed below. Additional discussions pertaining to the scram, loop shutdown and circulator trip inputs may be found in Sections 7.1.2.3, 7.1.2.4 and 7.1.2.6, respectively, of the FSAR. High moisture instrumentation is discussed in Section 7.3.2 of the FSAR.

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9 Fort St. Vrain #1 Technical Specifications Amendment #

Page 4.4-10a Basis for Specification LCO 4.4.1 (Continued)

To accommodate the i n strunien t dri f t assuned to occur between operational tests and the accuracy to which Trip Setpoints can be measured and calibrated, Allovable Values and Trip Setpoints have been specified in Part 1 of Tables 4.4-1 through 4.4-4 The methodology used for calculating the Allowable Values and Trip Setpoints is discussed in Technical Specification LSSS 3.3.

a. Scram Inputs The simultaneous insertion of the control rods will be initiated by the following conditions:

i Manual Scram A manual scram is provided to give the operator means for emergency shutdown of the reactor independent of the . automatic reactor protective system. The Reactor Mode Switch (RMS) in the "off" position also causes a manual scram.

Start-up Channel - High Count Rate High start up count rate is provided as a scram for use during fuel loading, preoperational testing, or other low power operations.

Linear Channel - High (Neutron Flux) l

.See Technical Specification LSSS 3.3.

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Fort St. Vrain #1 Technical Specifications Amendment #

Page 4.4-10b Basis for Specification LCO 4.4.1 (Continued)

Primary Coolant Moisture - High See Technical Specification LSSS 3.3.

Reheat Steam Temperature - High See Technical Specification LSSS 3.3.

Primary Coolant Pressure - Programmed Low See Technical-Specification LSSS 3.3.

Primary Coolant Pressure - Programmed High See Technical Specification LSSS 3.3.

Hot Reheat Header Pressure - Low Low reheat steam pressure is an indication of either a cold reheat steam line or a hot reheat steam line rupture in a section of line common to both loops.

Loss of the cold reheat steam line results in loss of the steam supply to the circulators which necessitates plant shutdown. The direct scram in this case precedes a scram resulting from the two-loop trouble.

The loss of either steam line results in loss of plant generation output, and a reactor scram is appropriate in this situation. The Trip Setpoint is selected to be below normal operating and transient levels, which vary over a wide range.

Main Steam Pressure - Low Low main steam pressure is an indication of main steam line rupture or loss of feedwater flow. Immediate shutdown of the reactor is appropriate in this case.

In addition, the superheater outlet stop check valves are automatically closed to reroute main steam to the flash tank (through the individual loop bypass valves and desuperheaters). This is required for the continued operation of the helium circulators on steam. The Trip Setpoint is selected to be below normal operating levels and system transients.

Plant Electrical System - Loss Loss of plant electrical system power requires a scram to prevent any Power-to-Flow mismatches from occurring. A preset time delay is pruvided following a power loss before the scram is initiated to allow an emergency diesel generator to start. If it does start, the scram is avoided.

Fort St. Vrain #1 Technical Specifications Amendment #

Page 4.4-10c 4

, Basis for Specification LCO 4.4.1 (Continued)

Two-Loop Trouble Scram logic Operation on one loop at a maximum of about 50% power ,

l may continue following the shutdown of the other loop (unless preceded by scram as in the case of high moisture). Onset of trouble in the remaining loop (two-loop trouble) results in a scram. Trouble is defined as a signal which normally initiates a loop shutdown. Similarly, simultaneous shutdown signals to both loops result in shutdown of one of the two loops only, and a reactor ser am. However, actuation of both Steam Line Rupture Detection / Isolation System (SLRDIS) loops, effectively shuts down both loops because it sends an actuation logic signal to all four circulator trip logic channels. The consequences of a two-loop shutdown and subsequent loss of forced circulation have been analyzed and found to be acceptable. The consequences are bounded by an interruption of forced circulation cooling accident described in FSAR Section 14.4.2.2, Safe Shutdown Cooling.

High Reactor Building Temperature (Pipe Cavity)

High temperature in the pipe cavity would indicate the presence of an undetected steam leak. A steam leak or pipe rupture under the PCRV within the support ring would also be detectable in the pipe cavity, therefore only one set of sensors and logic is required to monitor both areas. The setpoint has been set above the temperature that would be expected to occur in the pipe cavity if the steam leak were detected.

Fort'St, Vrain'#1' Technical Specifications Amendment #

Page 4.4-11 Basis for Spe'cification LCO'4.4.1'(Continued)

-b. Loop Shutdown-Inputs The .following loop. shutdown inputs are provided primarily for equipment protection and are not relied upon .to ' protect Safety Limits. Malfunction of these items could prevent a scra'n due to loss of the two loop trouble scram input.

Shutdown of Both Circulators (Loop Shutdown Logic) -

Shutdown :- of both circulators is a loop shutdown input which is necessary to ensure proper action of the reactor protective (scram) system through the two-loop trouble. scram in the event .of the loss of all circulators and low feedwater flow.

Steam Generator penetration Overpressure (Loop 1/ Loop 2)

Steam generator penetration overpressure is indicative of a pipe rupture within the penetration. A loop shutdown is appropriate for such an accident, and the helium' pressurizing line to the penetration is closed to prevent moisture backflow to the purified helium system. The penetration overpressure ~is handled by relief valves; however, to minimize the amount of

, steam / water released, the steam generator contents'are also dumped, j The steam generator interspace rupture discs are set at 825 psig (nominal). The burst pressure range (plus or minus 2%) is 809 psig to 842 (Technical Specification LSSS 3.3, Table 3.3-1), The relief valve is sized to allow a 370 psi pressure drop in a safety valve inlet line when the valve is relieving at nameplate capacity of 126,000 lb/hr superheated steam at 1000 degree F. This prevents the penetration pressure from exceeding the reference pressure of 845 psig.

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Fort St. Vrain #1 Technical Specifications Amendment #

Page 4.4-11a Basis for Specification LC0 4.4.1 (Continued).

High Reheat Header Activity - (Loop 1/ Loop 2)

High reheat header. activity is an indication of a reheater tube-rupture resulting in leakage of reactor helium into the steam system.' The' Trip Setpoint ensures detection of major reheat tube ruptures and an j on-scale reading, with up to design value circulating '

activity for post accident monitoring. Detection of ,

smaller size leaks or leaks with low circulating '

coolant activity can be detected and alarmed by the backup reheat condensate monitors and/or the air ejector monitor. l Low Superheat Header Temperature (Loop 1/ Loop 2) and -)

.High Differential Temperature Between Loop 1 and Loop 2 Low superheat header temperature in a loop is indicative either of a feedwater valve or' controller failure yielding an excessive loop feedwater flow rate or a deficiency of helium flow rate, and a loop.

shutdown is appropriate. The required coincident high differential temperature between loops functions to prevent the loop Trip from occurring during normal operation at low main steam temperatures such as in a normal plant shutdown.

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Fort St. Vrain #1 Technical-Specifications

. Amendment #

Page 4.4-12 Basis for Specification LCO 4.4.1 (Continued)'

c. ' Circulator Shutdown Inputs All circulator shutdown inputs (except circulator speed high on water turbines) are equipment protection items which are connected to two loop trouble through the loop shutdown system. These items are included in Table' 4.4-3 because a malfunction could prevent a scram due to loss of the two loop trouble scram input ~.

Circulator speed high on water turbines ~is included to assure continued core cooling capability on loss of steam drive.

Circulator Speed - Low Too low a circulator speed causes a mismatch betweer, thermal power input and heat removal (feedwater flow) in a steam generator, which may result in flooding the superheater section. The circulator Trip causes- an automatic adjustment, as required, in the turbine governor setting, feedwater flow rate, and remaining-circulator speed to maintain stable steam pressure and temperature conditions.

Loop 1/ Loop 2 Fixed Feedwater Flow - Low The Fixed Feedwater Flow - Low is an equipment protection feature designed to protect the steam generator from overheating for complete loss of feedwater flow.

' Loss of Circulator Bearing Water in order to . prevent circulator damage upon loss of normal and backup bearing water supplies, a ga, pressurized water accumulator is fired when water pressure falls below the Trip Setpoint value. The Trip Setpoint value is selected so that adequate water pressure is available during circulator coastdown, which lasts for about 30 seconds, to maintain clearances within the circulator bearings of at least 0.001 in. Tests and analyses have shown that a Trip at 450 psid provides substantial clearance margin i above 0.001 in, when the circulators are operating at normal speeds.

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Page 4.4-12a Basis for Specification LCO 4.4.1 (Continued)

Circulator penetration Trouble Circulator penetration overpressure is indicative of a pipe rupture within the penetration. A circulator Trip is appropriate for such an accident and the helium pressurizing line to the penetration is closed to prevent moisture backflow to the purified helium system. The overpressure is handled by the j penetration relief valves. The penetration interspace '

rupture discs are set at 825 psig (nominal). The burst pressure range (plus or minus 2*.) is 809 psig to 842 psig (Technical Specification LSSS 3.3, Table 3.3-1). The relief valve is sized to allow a 40 psi pressure drop in the safety valve inlet line when the valve is relieving at nameplate capacity (170 gpm).

Circulator Drain Malfunction This Trip is provided to prevent steam from entering the bearing of an operating circulator. A differential pressure controller is utilized to maintain the bearing water main drain pressure above the steam turbine exhaust pressure. When the pressure differential drops, the steam water drain control valves are opened to prevent steam from entering the bearings. If the above controls do not work, three PPS differential pressure switches for each circulator, set at greater than or equal to 8.5 psid, will initiate an automatic shutdown of the circulator.

Circulator Speed - High Steam The speed sensing system response and Trip setting are chosen so that under the maximum overspeed situation possible (loss of restraining torque) the circulator will remain within design criteria.

Circulator Trip - Manual (Steam / Water)

A manual Trip of each circulator for both steam and water turbine drives is available so that in an emergency an operator can trip a circulator when required.

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Page 4.4-12b

' Basis for Specification LC0 4.4.1 (Continued)

Circulator Seal Malfunction (Low /High)

A high reverse differential of -6.1" H2O would be reasonable evidence that bearing water is leaking into the primary coolant system. An increasing differential cressure of +76.1" H2O would be reasonable e,"dence that primary coolant is leaking into the bearing water and thus into the closed circulator service system. In both cases a circulator trip with brake and seals set is appropriate.

Circulator Speed - High Water The Trip Setpoint has been established above normal operating speed. Equipment testing ensures that this Trip Setpoint will prevent failure due to fatigue cracking.

Steam Leak Detection in the Reacter Building Steam Leak Detection in the Reactor Building is required for equipment qualification of Safe Shutdown Cooling Systems. The ALLOWABLE VALUE is set at 5 52.8 degrees F per minute rate of rise in order to prevent exceeding the harsh environment temperature profile to which the safe shutdown electrical equipment is qualified, per the requirements of 10CFR50.49. A setpoint calculation analysis performed per ISA Standard 567.04 and RG1.105 results in the stated ALLOWABLE VALUE and TRIP SETPOINT as specified in the LCO and this basis. The TRIP SETPOINT has been established with sufficient margin between the technical specification limit for the process variable and the nominal TRIP SETPOINT to allow for

1) inaccuracy of the instruments; 2) uncertainties in the calibration; 3) instrument drift that could occur during the interval between calibrations; and 4) inaccuracies due to ambient temperature changes, vibration and other environmental conditions. The TRIP SETPOINT is set at 5 52.3 degrees F per minute rate of rise until such time as the drift characteristics of the detection system are better understood from actual plant operating experience and the assumptions used in the setpoint analysis are verified.

SLRDIS design incorporates two panels, each with its own set of sensors for the Reactor and Turbine Buildings and dual logic trains in each panel. The SLRDIS design preserves the single failure concept. A single failure will neither cause nor prevent SLRDIS actuation in the event of a high energy line break.

The probability of an inadvertent actuation is extremely small due to the matrix logic employed for circulator trip and valve actuation. The SLRDIS panels are referred to as " loops"; however, due to the way the outputs of the panels are combined to provide i i

protective action and satisfy the single failure concept, the SLRDIS loops do not correspond to primary or secondary loops.

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For each SLRDIS loop, the OPERABILITY requirements and their respective ACTIONS represent good operating practices and judgment for a four channel detection system with a 2 of 4 coincidence trip logic. The fourth channel may be placed in bypass for test and/or maintenance purposes, subject to the ACTION statement restrictions, while preserving a 2 of 3 coincidence logic OPERABLE. The Steam Line Rupture Detection / Isolation System as designed and installed has spare channels available for input. Any of the available channels may be selected for input signal processing provided the surveillance are current on the channels used. The SLRDIS is required to be OPERABLE only at power (above 2% rated thermal power).

Analyses with rated reactor power at 2% demonstrate that automatic actuation of SLRDIS is not likely to occur during a high energy line break lasting until it is manually terminated at one hour following initiation. The temperatures as analyzed in both the reacter and turbine buildings stay well below the temperature for which the equipment is qualified.

'The ACTION statements for inoperable SLRDIS detection and information processing equipment allow one channel in each building to be inoperable for up to 7 days; a second inoperable channel in either building ' requires that power be reduced to below 2% within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.

The 7 day ACTION time for a single detector channel is acceptable based on preservation of a 2 out of 3 coincidence detection system still in operation.

ACTION 3 is applicable to other functions within the SLRDIS instrumentation panel su:h as loss of power from instrument buses, or other failures in the logic trains and associated electronics. A 12 hour1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> time period in ACTION 3 for inoperability of those associated SLRDIS functions minimized the time that SLRDIS may operate with limited functional capability.

An inoperab,le valve or associated equipment is allowed for 72 , hours. High energy line break analysis for environmental qualification assumes the worst-case single active failure. Thus, a single valve inoperable for up to 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> is within the bounds of analysis When two or more valves and/or associated equipment is inoperable, 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> is allowed to restore the inoperable equipment. Repairs may be performed while the plant is at power, thus, minimizing thermal cycling of plant and installed equipment.

Steam Leak Detection in the Turbine Building is required for equipment qualification of Safe Shutdown Cooling Systems. Thus, the limits and basis are the same as discussed in the basis for steam leak .

detection in the reactor building.

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Page 4.4-13 Basis for Specification LCO 4.4.1 (Continued)

d. ,Rpd Withdrawal Prohibit Inputs The termination of control rod withdrawal to prevent further reactivity addition will occur with the following conditions:

Startup Channel - Low Count Rate Start-up Channel -

Low Count Rate is provided to prevent control rod pair withdrawal and reactor startup without adequate neutron flux indication. The trip level is selected to be above the background noise level.

Linear Channel - Low Power RWP Linear Channel (5% Power) directs the reactor operator's attention to either a downscale failure of a ' power range channel or improper positioning of the Interlock Sequence Switch.

Linear Channel - High Power RWP Linear Channel (30% Power) is provided to prevent control rod pair withdrawal if reactor power exceeds the Interlock Sequence Switch lireit for the " Low Power" position.

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