ML20099G749

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Proposed TS SR 4.6.2.3.b Re RHR Pump Performance in Suppression Pool Cooling Mode of Operation
ML20099G749
Person / Time
Site: Limerick  Constellation icon.png
Issue date: 08/11/1992
From:
PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:
Shared Package
ML20099G746 List:
References
NUDOCS 9208170192
Download: ML20099G749 (7)
v • d • e


Text

. - - . _ _ . . -. -,.

( . .

. ATTACHMENT 2

-LIMERICK GENERATING STATION Units 1 and 2 Docket Nos. 50-352 50-353 License Nos. NPF-39 NPF-85

-PROPOSED TECHNICAL SPECIFICATIONS CHANGES No. 92-09 List of-Attached-Pages Unit 1 L 3/4 6-16 B 3/4 6-3 B 3/4 6-3a Unit 2 1

3/4 6-16 B 3/4 6-3 i: 8 3/4'6-3a l

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CONTAINMENT SYSTEMS-

, SUPPRESSION POOL COOLING LIMITING __ CONDITION FOR OPERATION-3.6.2.3 The suppression pool cooling mode-of the residual heat renoval-(RHR) system shall be OPERABLE with two independent loops, each loop consisting of:

a. One OPERABLE RHR pump, and
b. -An OPERABLE. flow patn capable of recirculating water from the suppression chamber through an RHR heat exchanger.

APPLICABILITY: OPERATIONAL CONDITIONS 1, 2, and 3.

ACTION:

a. With one suppression pool cooling loop inoperable, restore the inoperable loop to OPERABLE status within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> or be in at least HOT SHUTDOWN within the'next 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and in COLD SHUT 00WN within the following 24 hourt
b. With both~ suppression pool cooling loops inoperable, be in at least HOT SHUTDOWN within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and in COLD SHUTDOWN
  • within the next 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

SURVEILLANCE REQUIREMENTS 4.6.2.3 _The suppression pool cooling mode _of the RHR system shall be demonstrated OPERABLE:

a. At_least once per 31 days by verifying that each valve-(manual, power-operated, or automatic) in the flow path that is not locked.. sealed, or otherwise secured in position, is in its correct position.
b. By verifying that each of the required RHR-pumps _ develops a flow of us least 10,000 gpm on recirculation flow through the flow path including the RHR heat exchanger and its associated closed _ bypass valve,-the suppression pool ~and the full _ flow test line when tested-pursuant to Specification 4.0.5.
  • Whenever both RHR subsystems are inoperable, if unable to attain COLD SHUTDOWN

.as' required by this ACTION,_ maintain reactor coolant-temperature as low as practical by use-of; alternate. heat removal methods.

LIMERICK-- UNIT 1 3/4 6-16

CONTA'INMENT-SYSTEMS

-BASES 3/4.6.2 DEPRESSURIZATION SYSTEMS The specifications of this section ensure that the primary containment pressure will not exceed the design pressure of 55 psig during primary system blowdown from full operating pressure.

The suppression chamber water provides the heat sink for the reactor coolant system _ energy release following a postulated rupture of the system. The suppression chamber water volume must absorb the associated decay and structural sensible heat' released during reactor coolant system blowdown from 1040 psig.

Since all of the gases in the drywell are purged into the suppression chamber air space during a loss-of-coolant accident, the pressure of toe suppression chamber air space must not exceed 55 psig. The design volume of the suppression chamber, water and air .was obtained by considering that the total volume of reactor coolant is discharged to the suppression chamber and that the drywell volume is purged to the suppression chamber.

Using the minimum or maximum water volumes given in this specification, suppression pool pressure during the design basis accident is approximately 30 psig which3is below the design pressure of 55 psig. Maximum water volume of 134,600 ft rgsultsinadowncomersubmergenceof12'3"andtheminimumvolume of :122,120 f t results-in_a submergence approximately 2'3" less. The majority of the Bodega tests were run with a submerged length of 4 feet and with complete condensation. Thus, with respect to the downcomer submergence, this specification is adequate. Themaximumtemperatureatgheendoftheblowdowntestedduringthe l

Humboldt Bay and Bodega-Bay tests was 170 F and this is conservatively taken

_tobethelimitforcompletecondensationoftheregctorcoolant,although condensation would occur for temperatures above 170 F.

Should it be necessary to make the suppression chamber inoperable, this shall only:be done as specified in Specification 3.5.3.

Underfullpoweroperatingconditions,blowdownthroughsafgty/reliefvalves

.assuminganinitial-suppressionchamberwatgrtemperatureof95Fresultsina bulk water temperature of approximately 136 F immediately following blowdown which is below the 190 F bulk temperature limit used for complete condensation via T-quencher-devices. At this temperature and atmospheric pressure, the available NPSH exceeds that. required by both the RHR and core spray pumps, thus there-is no dependency on containment overpressure during the accident injection

phase.- If-both RHR loops are used for containment cooling, there is no dependency on containment overpressure for post-LOCA operations.

LIMERICK - UNIT 1 8 3/4 6-3

3/_4.6.2 DEPRESSURIZATION SYSTEMS (cont.)

0'ne of the surveillance requirements for the suppression pool cooling (SPC)  !

mode of the RHR system is to demonstrate that each RHR pump develops a flow rate

.t10,000 gpm while operating in the SPC mode with flow through the heat exchanger and its associated closed bypass valve, ensuring that pump performance  ;

has not degraded during the cycle and that the flow path is operable. This test i confirms one point on the pump design curve and is indicative of overall i performance. Such inservice inspections confirm component operability, trend performance and detect incipient failures by indicating abnormal performance. The !

RHR heat exchanger bypass valve is used for adjusting flow through the heat  !

exchanger, and is not designed to be a tight shut-off valve. With the bypass i valve closed, a portion of the total flow still travels through the bypass, which ,

can affect overall heat transfer. However, no heat transfer performance  !

requirement of the heat exchanger is intended by the current Technical Specification surveillance requirement. This is confirmed by the lack of any flow requirement for the RHRSW system in Technical Specifications Section 3/4.7.1.

Verifying an RHR flowrate through the heat exchanger does not demonstrate heat -

removal capability in the absence of a requirement for RHRSW flow. LGS does perform heat trans'er te* ding of the RHR heat exchangers as part of its response toGenericLetter89-13,whichvarifiedthecommitmenttomeettherequirementsofl; GDC 46, Experimental data indicate that excessive steam condensing loads can be avoided if the peak local temperature of the suppression pool is maintained below 200 F during any period of relief valve operation for T-quencher devices.

Specifications have been placed on the envelope of reactor operating conditions so that the reactor can be depressurized in a timely manner te avoid the regime of potentially high suppression chamber loadings.

LIMERICK - UNIT 1 B 3/4 6-3a

CONTAINMENT SYSTEMS SUPPRESSION POOL COOLING LINITINGCONDITIONFOROPERA110H 3.6.2.3 The suppression pool cooling rnode of the residual heat removal (RHR) system shall be OPERABLE with two independent loops, each loop consisting of:

a. One OPERABLE RHR pump, and
b. An OPERA"LE flow path capable of recirculating water from the suppression chamber through an RHR heat exchanger.

APPLICABILITY: OPERATIONAL CONDITIONS 1, 2, and 3.

ACTION: --

a. With one suppression pool cooling loop inoperable, restore the inoperable loop to OPERABLE status within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> or be in at least HOT SHUTDOWN within the next 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and in COLD SHUTDOWN within the following 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.
b. With both suppression pool cooling loops inoperat.le, be in at least HOT SHUTDOWN within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and in COLD SHUTDOWN
  • within the next 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, c

SURVEILLANCE REQUIREMENTS 4.6.2.3 The suppression pool cooling mode of the RHR system shall be demonstrated OPERABLE:

a. At least once per 31 days by verifying that each valve (manual, power- $

operated, or automatic) in the flow path that is not locked, sealed, or otherwise secured in position, is in its correct position,

b. By verifying that each of the required RHR pumps develops a flow of at least 10,000 gpm on recirculation flow through the flow path including the RHR heat exchanger and its associated closed bypass valve, the suppression pool and the full flow test line when tested pursuant to Specification 4.0.5.
  • Whenever both RHR subsystems are inoperable, if unable to attain COLD SHUTDOWN as required by this ACTION, maintain reactor coolant temperature as low as practical by use of alternate heat removal methods.

LIMERICK - UNIT 2 3/4 6-15

, CONTAINMENT SYSTEMS BASES 3_/4.6.2 DEPRESSURIZATION SYSTEMS The specifications of this section ensure that the primary containment pressure will not exceed the design pressure of 55 psig during primary system blowdown from full operating pressure.

-The suppression chamber water provides the heat sink for the reactor coolant system energy release following a postulated rupture of the system. The

-suppression chamber water volume must absorb the associated decay and structural sensible heat released during reactor coolant system blowdown from 1040 psig.

Since all of the gases in the drywell are purged into the suppression chamber air space during a loss-of-coolant accident, the pressure of the suppression chamber air space must not exceed 55 psig. The design volume of the suppression chamber, water and air, was obtained by considering that the total volume of reactor coolant is discharged-to the suppression chamber and that the drywell volume is purged to the suppression chamber.

Using the minimum or maximum water volumes given in this specification.

suppression pool pressure during the design basis accident is approximately 30 psig which3is below the design pressure of 55 psig. Maximum water volume of 134,600 ft r sults in a downcomer submergence of 12'3" and the minimum volume s i

of 122.120 ft results in a submergence approximately 2'3" less. The majority of the Bodega tests were run with a submerged length of 4 feet and with complete condensation.. Thus, with respect to the downcomer submergence, this specification is adequate. Themaximumtemperatureatgheendoftheblowdowntestedduringthe Humboldt Bay and Bodega Bay tests was 170 F and this is conservatively taken tobe.thelimitforcompletecondensationoftheregctorcoolant,although condensation would occur for temperatures above 170 F.

Should it be necessary to make the suppression chamber inoperable, this shall only-be done as specified in Specification 3.5.3.

Underfullpoweroperatingconditions,blowdownthroughsafgty/reliefvalves assumingan'initialsuppressionchamberwatgrtemperatureof95Fresultsina bulk water temperature of approximately 136 F-immediately following blowdown

-which is below the.1900F bulk temperature limit used for complete condensation via T-quencher devices. At this temperature and atmospheric pressure, the available NPSH exceeds that required by both the RHR and core spray pumps, thus there,is no dependency on containment overpressure during the accident injection phase. .lf_both RHR loops are used for containment cooling, there is no dependency on containment overpressure for post-LOCA operations.

LIMERICK - UNIT 2 8 3/4 6-3

)

~ '

3/4.6.2 DEPRESSURIZATION SYSTEMS (cont.)

dneofthesurveillancerequirementsforthesuppressionpoolcooling(SPC)-

mode of the RHR system is to-demonstrate that each RHR pump develops a flow rate 210,000 gpm while operating in~the SPC mode with flow through the heat

-exchanger and its associated closed bypass valve, ensuring that pump performance

~has not degraded during the cycle and that the flow path is operable. This test confirms one point on the-pump design curve and is indicative of overall performance. Such 1nservice inspections confirm component operability, trend performance and detect incipient failures by indicating abnormal performance. The RHR_ heat exchanger bypass valve is used for adjusting flow through the heat exchanger, and is not designed to be a tignt shut-off valve. With the bypass valve closed, a portion of the total flow still travels through the bypass, which can affect overail-heat transfer. However nn heat transfer performance requirement of the heat exchanger is-intended by the current Technical Specification surveillance requirement. This is confirmed by the lack of any flow requirement for the RHRSW system in Technical Specifications Section 3/4.7.1.

Verifyir.g an RHR flowrate through the heat exchanger does not demonstrate heat

-removal capability in the absence of a requirement for RHRSW flow. LGS does perform _ heat transfer testing of the RHR heat exchangers as part of its response

-to Generic Letter 89-13, which verified the commitment to meet the requirements of GDC 46.

Experimental data indicate-that excessive steam condensing loads can be avoided if the peak local temperature of the suppression pool is maintained below 2000 F during any period of relief valve operation for T-quencher devices.

Specificat_ ions have been placed on the envelope of reactor operating conditions so that-the reactor-can be-depressurized in a timely manner to avoid the regime of potentially high suppression chamber loadings.

LIMERICK - UNIT 2 B 3/4 6-3a

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