Text

Proposed Tech Specs Revising Requirements for Detection & Suppression of Core Thermal Hydraulic Instabilities
	ML20209B702
Person / Time
Site:	Brunswick
Issue date:	01/28/1987
From:	; CAROLINA POWER & LIGHT CO.
To:	;
Shared Package
ML20209B687	List: ML20209B683; ML20209B702;
References
	NLS-86-388, NUDOCS 8702040103
	Download: ML20209B702 (12)
	v • d • e

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ENCLOSUREI TO SERIAL: NLS-86-388 PROPOSED TECHNICAL SPECIFICATION PAGES BRUNSWICK-1 BWR Core Thermal Hydraulic Stability (85TSB28)

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SUMMARY

LIST OF REVISIONS PAGE NO.

DESCRIPTION OF CHANGES 3/44-1 Revised TS 3/4 4.1.1 to incorporate General Electric's SIL-380 recommendations.

3/4 4-la New page required due to expansion of Section 3/4 4.1.1.

3/4 4-lb New Figure 3.4.1.1-1, " Thermal Power Limitations",

incorporated to support the revisions to the text.

B3/4 4-1 Revised the bases of Section 3/4 4.1 to incorporate General Electric's SIL-380 recommendations.

4 l

(50268AT/bac)

(BSEP-1-92) 3/4.4 REACTOR COOLANT SYSTEM 3/4.4.1 RECIRCULATION SYSTEM RECIRCULATION LOOPS LIMITINC CONDITION FOR OPERATION 3.4.1.1 Two reactor coolant recirculation loops shall be in operation with the cross-tie valve closed, the pump discharge valves OPERABLE, and the pump-

. discharge bypass valves OPERABLE or closed and a.

Total core flow shall be greater than or equal to 35 million 1bs/hr, or b.

THERMAL POWER shall be less than or equal to the limit specified in Figure 3.4.1.1-1.

APPLICABILITY: OPERATIONAL CONDITIONS 1* and 2*.

ACTION:

a.

With both reactor coolant system recirculation loops not in operation, inunediately initiate an orderly reduction of THERMAL POWER so that it is less than.or equal to the limit specified in Figure 3.4.1.1-1 within 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months , and restore both loops to operation within 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months or be in at -

least HOT SHUTDOWN within the next 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months .

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b.

With one reactor coolant system recirculation loop not in operation, immediately initiate either an orderly reduction of THERMAL POWER so that it is less than or equal to the limit specified in Figure 3.4.1.1-1 within 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months or increase core flow so that it is greater than or equal to the limit specified in Figure 3.4.1.1-1 within 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months , and restore both loops-to operation within 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months or be in at least HOT SHUTDOWN within the next 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months .

c.

With two reactor coolant system recirculation loops in operation and total core flow less than 35 million 1bs/hr and THERMAL POWER greater than the limit specified in Figure 3.4.1.1-1:

1.

Immediately initiate action to reduce THER:{AL POWER so that it is less than or equal to the limit specified in Figure 3.4.1.1-1 within 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months , or i

2.

Immediately initiate action to increase core flow so that it is greater than 35 million Ibs/hr within 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months , or 3.

Determine the APRM and LPRM neutron flux noise levels within 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months , l

and a)-

If the APRM and LPRM neutron flux noise levels are less than three times their established baseline levels or less than 5% peak-to peak, continue to determine the noise levels at least once per 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months and within I hour after the completion of a i

THERMAL POWER increase of at least 5% of RATED THERMAL POWER, or I

b)

If the APRM or LPRM neutron flux noise levels are greater than i

or equal to three times their established baseline levels and greater than 5% peak-to peak, levels to within the requiredinunediately initiate co i

action and restore the noise l

limits within 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months by increasing core flow to greater than 35 l

million Ibs/hr and/or by initiating an orderly reduction of

See Special Test Exception 3.10.4.

i t

j BRUNSWICK - UNIT 1 3/4 4-1 Amendment No.

i

(BSEP-1-92) 3/4.4 REACTOR COOLANT SYSTEM i

LIMITING CONDITION FOR OPERATION (Continued)

ACTION:

(Continued)

THERMAL POWER to less than or equal to the limit specified in Figure 3.4.1.1-1.

SURVEILLANCE REQUIREMENTS 4.4.1.1.1 Each pump discharge valve and bypass valve shall be demonstrated l

OPERABLE by cycling each valve through at least one complete cycle of full travel during each COLD SHUTDOWN which exceeds 48 hours5.555556e-4 days 0.0133 hours 7.936508e-5 weeks 1.8264e-5 months , if not performed in the previous 31 days.

4.4.1.1.2 Each pump discharge bypass valve, if not OPERABLE, shall be l

verified to be closed at least once per 31 days.

4.4.1.1.3 Establish baseline APRM and LPRM neutron flux noise values at a point below the 100% rated rod line during startup testing following each refueling outage.

1 e

i BRUNSWICK - UNIT 1 3/4 4-la Amendment No.

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(BSEP-1-92) 3/4.4 REACTOR COOLANT SYSTEM BASES 3/4.4.1 RECIRCULATION SYSTEM Operation with a reactor core coolant recirculation loop inoperable is restricted until an evaluation of the performance of the ECCS during one loop operation has been performed, evaluated, and determined to be-acceptable.

An inoperable jet pump is not, in itself, a sufficient reason to declare a recirculation loop inoperable, but it does present a hazard in case of a design basis accident by increasing the blowdown area and eliminating the capability of reflooding the core. Thus, the requirement for shutdown of the facility with a jet pump inoperable.

In order to prevent undue stress on the vessel nozzles and bottom head 0

region, the recirculation loop temperatures should be within 50 F of each other prior to, start-up of an idle loop.

Since the coolant in the bottom of the vessel is at a. lower temperature than the water in the upper regions of the core, undue str'ess on the vessel 0

would result if the' temperature difference were greater than 145 F.

Neutron flux noise limits are established to ensure early detection of j

limit cycle neutron flux oscillations. BWR cores typically operate with neutron flux noise caused by random boiling and flow noise. Typical neutron I

flux noise levels of 1 to 12% of rated power (peak-to peak) have been reported for the range of low to high recirculation loop flow during both single and dual recirculation loop operation. Neutron flux noise levels significantly larger than these values are considered in the thermal / mechanical fuel design and are found to be of negligible consequence.

In addition, stability tests at operating BWR's have demonstrated that when stability related neutron flux limit cycle oscillations occur they result in peak-to peak neutron flux limit cycles 5 to 10 times the typical values. Therefore, actions taken to reduce neutron flux noise levels exceeding three (3) times the typical value are sufficient to ensure early detection of limit cycle neutron flux oscillations.

2 l

Data to establish baseline APRM and LPRM neutron flux noise values is j

obtained at a point below the 100% rated rod line. A minimum of two detectors of one LPRM string per core octant and two detectors of one LPRM string near i

i the center of the core should be monitored. Detectors used for monitoring j

should be selected to provide core wide representation.

Substitutions are permitted for inoperable LPRM detectors.

These specifications are based on the guidance of General Electric SIL #380, Rev. 1, 2-10-84 i

BRUNSWICK - UNIT 1 B 3/4 4-1 Amendment No.

I

ENCLOSURE 2 TO SERIAL: NLS-36-388 PROPOSED TECilNICAL SPECIFICATION PAGES BRUNSWICK-2 (85TSB28) l l

l (50268AT/bmc)

SUMMARY

LIST OF REVISIONS PAGE NO.

DESCRIPTION OF CHANGES 3/44-1 Revised TS 3/4 4.1.1 to incorporate General Electric's SIL-380 recommendations concerning thermal hydraulic stability.

3/4 4-la New page required due to expansion of TS 3/4 4.1.

3/4 4-lb New Figure 3.4.1.1-1, " Thermal Power Limitations",

incorporated to support the revisions to the text.

B3/4 4-1 Revised the bases to Section 3/4 4.1 to incorporate General Electric's SIL-380 recommendations.

l 4

I (5026 BAT /bac )

~

(BSEP-2-95) 3/4.4 REACTOR COOLANT SYSTEM 3/4.4.1 RECIRCULATION SYSTEM RECIRCULATION LOOPS LIMITING CONDITION FOR OPERATION 3.4.1.1 Two reactor coolant recirculation loops shall be in operation with the cross-tie valve closed, the pump discharge valves OPERABLE, the pump discharge bypass valves OPERABLE or closed and Total core flow shall be greater than or equal to 35 million 1bs/hr, or a.

b.

THERMAL POWER shall be less than or equal to the limit specified in Figure 3.4.1.1-1.

APPLICABILITY: OPERATIONAL CONDITIONS 1* and 2*.

ACTION:

With both reactor coolant system recirculation loops not in operation,is a.

immediately initiate an orderly reduction of THERMAL POWER so that it less than or equal to the limit specified in Figure 3.4.1.1-1 within 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months , and' restore both loops to operation within 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months or be in at least HOT SHUTDOWN within the next 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months .

\\

b.

With one reactor coolant system recirculation loop not in operation, immediately initiate either an orderly reduction of THERMAL POWER so that it is less than or equal to the limit specified in Figure 3.4.1.1-1 within 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months or increase core flow so that it is greater than or equal to the limit specified in Figure 3.4.1.1-1 within 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months , and restore both loops to operation within 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months or be in at least HOT SHUTDOWN within the next 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months .

With two reactor coolant system recirculation loops in operation and total c.

core flow less than 35 million Ibs/hr and THERMAL POWER greater than the limit specified in Figure 3.4.1.1-1:

1.

Immediately initiate action to reduce THERMAL POWER so that it is less than or equal to the limit specified in Figure 3.4.1.1-1 within 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months , or 2.

Immediately initiate action to increase core flow so that it is greater than 35 million lbs/hr within 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months , or 3.

Determine the APRM and LPRM neutron flux noise levels within 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months , and:

a)

If the APRM and LPRM neutron flux noise levels are less than three times their established baseline levels or less than 5%

peak-to peak, continue to determine the noise levels at least once per 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months and within 1 hour1.157407e-5 days 2.777778e-4 hours 1.653439e-6 weeks 3.805e-7 months af ter the corepletioa of a THERMAL POWER increase of at least 5% of RATED THERMAL POWER, or b)

If the APRM or LPRM neutron flux noise levels are greater than or equal to three times their established baseline levels and greater than 5% peak-to peak, immediately initiate corrective i

action and restore the noise levels to within the required i

limits within 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months by increasing core flow to greater than 35 million Ibs/hr and/or by initiating an orderly reduction of

See spectat Test t;xcepcion 3.10.4.

BRUNSWICK - UNIT 2 3/4 4-1 Amendment No.

(BSEP-2-95) 3/4.4 REACTOR COOLANT SYSTEM LIMITING CONDITION FOR OPERATION (Continued)

ACTION:

(Continued)

THERMAL POWER to less than or equal to the limit specified in l

Figure 3.4.1.1-1.

SURVEILLANCE REQUIREMENTS 4.4.1.1.1 Each pump discharge valve and bypass valve shall be demonstrated l

OPERABLE by cycling each valve through at least one complete cycle of full travel during each COLD SHUTDOWN which exceeds 48 hours5.555556e-4 days 0.0133 hours 7.936508e-5 weeks 1.8264e-5 months , if not performed in the previous 31 days.

4.4.1.1.2 Each pump discharge bypass valve, if not OPERABLE, shall be l

verified to be closed at least once per 31 days.

4.4.1.1.3 Establish baseline APRM and LPRM neutron flux noise values at a point below the 100% rated rod line during startup testing following each refueling outage.

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4 BRUNSWICK - UNIT 2 3/4 4-la Amendment No.

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(BSEP-2-95) 3/4.4 REACTOR COOLANT SYSTEM BASES 3/4.4.1 RECIRCULATION SYSTEM Operation with a reactor core coolant recirculation loop inoperable is restricted until an evaluation of the performance of the ECCS during one loop operation has been performed, evaluated, and determined to be acceptable.

An inoperable jet pump is not, in itself, a sufficient reason to declare a recirculation loop inoperable, but it does present a hazard in case of a design basis accident by increasing the blowdown area and eliminating the capability of reflouding the core. Thus, the requirement for shutdown of the facility with a jet pump inoperable.

In order to prevent undue stress on the vessel nozzles and bottom head region, the recirculation loop temperatures should be within 50*F of each other prior to start-up of an idle loop.

Since the coolant in the bottom of the vessel is at a lower temperature than the water in the upper regions of the core, undue stress on the vessel 0

would result if the temperature difference were greater than 145 F.

~

Neutron flux noise limits are established to ensure early detection of limit cycle neutron flux oscillations.

BWR cores typically operate with neutron flux noise caused by random boiling and flow noise. Typical neutron flux noise levels of 1 to 12% of rated power (peak-to peak) have been reported for the range of low to high recirculation loop flow during both single and i

i dual recirculation loop operation. Neutron flux noise levels significantly larger than these values are considered in the thermal / mechanical fuel design and are found to be of negligible consequence.

In addition, stability tests at operating BWR's have demonstrated that when stability related neutron flux limit cycle oscillations occur they result in peak-to peak neutron flux limit I

cycles 5 to 10 times the typical values. Therefore, actions taken to reduce neutron flux noise levels exceeding three (3) times the typical value are sufficient to ensure early detection of limit cycle neutron flux oscillations.

i Data to establish baseline APRM and LPRM neutron flux noise values is obtained at a point below the 100% rated rod line. A minimum of two detectors of one LPRM string per core octant and two detectors of one LPRM string near the center of the core should be monitored. Detectors used for monitoring should be selected to provide core wide representation. Substitutions are permitted for inoperable LPRM detectors.

These specifications are based on the guidance of General Electric SIL #380, Rev. 1, 2-10-84.

BRUNSWICK - UNIT 2 B 3/4 4-1 Amendment No.

i'

ML20209B702

Text

SUMMARY

SUMMARY

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