ML20077D964
| ML20077D964 | |
| Person / Time | |
|---|---|
| Site: | Point Beach  |
| Issue date: | 05/30/1991 |
| From: | Fay C WISCONSIN ELECTRIC POWER CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| Shared Package | |
| ML20077D966 | List: |
| References | |
| CON-NRC-91-050, CON-NRC-91-50 GL-90-06, GL-90-6, VPNPD-91-175, NUDOCS 9106050324 | |
| Download: ML20077D964 (16) | |
Text
-- __ -_ _. _
Wisconsin Electnc POWER COMPANY
__231 W Mahigan. Po Boa 204$, Mhouvee VA 53201 (414) ??i D45 VPNPD-91 _175 10 CFR 50.59 NRC 050 10 CFR 50.90 10 CFR 50.4 May 30,-1991 U. S. NUCLEAR REGULATORY COMMISSION Document Control Desk Mail Station P1-137 Washington, D. C. 20555 Gentlemen: '
DOCKETS 50-266 AND 50-301 TECHNICAL SPECIFICATION CHANGE REOUEST 145 PRESSURIZER PORV AND BLOCK VALVE REOUIREMENTS and OVERPRESSURE MITIGATING SYSTEM OPERATIONS POINT BEACH-NUCLEAR PLANT, UNITS 1 AND 2 In accordance with the. requirements of 10 CFR 50.59(c), 50.90,
- and 50.4, Wisconsin Electric Power Company (Licensee) hereby requests amendments to Facility Operating Licen.es DPR-24 and DPR-27 for Point Beach Nuclear Plant, Units 1 and 2 respectively, to incorporate changes in the plant Technical Specifications.
The proposed changes,-asidetailed below, revise Specifications 15.3.1.A.S and 15.3.15 and Tables 15.4.1-1 and 15.4.1-2. The.
changes-specify'more stringent Limiting Conditions for Operation (LCOs)-and Surveillance Requirements for. pressurizer power-operated relief vhlves-(PORVs)' and block valves. Marked-up copies of the applicable-Technical-Specification pages containing the changes proposed-in'this application are attached.
We are proposing these changes to'our Technical Specifications to conform to the Nuclear Regulatory Commission's position that was
- conveyed in Generic Letter (GL) 90-06. That letter provided the Nuclear Regulatory Commission's plan for resolution of Generic
' Issue 70, " Power-operated Relief Valve and Blocking Valve Reliability" and Generic Issue 94, " Additional Low-Temperature Overpressure Protection for Light Water Reactors." In our November 14, 1990 response to GL 90-06, we committed to revise ;j our--Technical Specifications based on the'model specifications ,
that had been provided as attachments to the Generic Letter, i
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MRC Document Control Desk May 30, 1991 i Page 2 Generic Issue 70, " Power-Operated Relief Valve and Blocking Valve Reliability" revealed that, although PORVs and block valves were not originally designed as safety-related components, they are now utilized to perform some functione., such as mitigation of a design-basis steam generator tube rupture accident and low-temperature overpressure protection (LTOP) of the reactor vessel during startup and shutdown. GL 90-06 addressed Generic Issue 70 and mandated Technical Specification revisions aimed at improving the reliability of PORVs and block valves. Our proposed changes to Specification 15.3.1.A.5, " Pressurizer Power-Operated Relief Valves and PORV Block Valves", incorporate the guidance contained in GL 90-06. These changes are discussed as follows:
A. Specification 15.3.1.A.S.a.(1) states that, if a PORV is inoperable due to excessive seat leakage greater than the Technical Specification limit, within one hour either the PORV must be restored to an operable condition or the associated block valve must be closed. The change proposed with this application requires that when a PORV seat leaks excessively, the associated block valve must be closed with electrical power maintained to the block valve. The block valve is closed to maintain the reactor coolant pressure boundary integrity. Power is maintained to the block valve so that the block valve remains available and, it necessary, the block valve can be opened to allow the PORV to control reactor coolant system pressure. Finally, the basis for this specification has been changed to state that the block valve (s) may remain closed to isolate a PORV with excessive seat leakage for a limited period of time not to exceed the end of the next refueling shutdown. In the past we have consistently performed corrective maintenance on inoperative PORVs during refueling shutdowns. In the future, we fully intend to continue to perform corrective maintenance on inoperative PORVs during refueling shutdowns.
B. Specification 15.3.1.A.S.a.(2) states that, if a PORV is considered inoperable due to a channel fu.nctional test failure, within one hour either the associated PORV channel switch must be restored to an operable condition or the associated block valve must be closed. Our proposed change has more comprehensive wording in that it encompasses PORVs that are " inoperable for reasons other than that of excessive seat leakage" rather than just those that are
" inoperable due to a channel functional test failure." The proposed change also requires that when a PORV is inoperable for reasons other than excessive seat leakage, the block valve must be shut with electrical power removed. Removing electrical power prevents the block valve from inadvertently opening while its associated PORV could potentially be open due to maintenance.
NRC Document Control Desk May 30, 1991 Page 3 i
C. Specification 15.3.1.A.5 does not currently address the situation in which two PORVc are inoperable. Our proposed change, 15.3.1.A.5.a.(3), specifies that at least one PORV must be returned-to an operable status within one hour.
D. Existing specification 15.3.1.A.5.a.(3) currently states that, if a block valve is inoperable, the block valve shall be restored to an operable condition within one hour or the block valve shall be closed with power removed from the block valve. The proposed change, 15. 3 .1. A . 5. a . ( 4 ) ,
requires that when a block valve is inoperable, the associated PORV must be placed in manual control. Placing the PORV in manual control precludes the PORV from automatically opening for an overpressure event and it minimizes the potential for a stuck-open PORV at a time when the block valve is inoperable. The proposed change deletes the requirement to close the inoperative block valve because such action would probably not be possible when the block valve is inoperable.
E. Specification 15.3.1.A.5 does not currently address the situation in which both block valves are inoperable. The proposed change, 15. 3.1. A . S . a . ( 5) , specifies that when both block valves are inoperable, one block valve must be restored to an operable condition within one hour.
F. In its discussion of Generic Issue 70, GL 90-06 also mandated several changes to surveillance requirements involving PORVs. These changes have been incorporated into our proposal and are discussed below:
- 1. Table 15.4.1-2, " Minimum Frequencies for Equipment and-Sampling Tests," lists surveillance requirements for various equipment. The proposed change modifies Item 23, "PORV Block Valves," deleting the requirement to cycle block valves that have been shut to isolate a PORV that is inoperable for reasons other than excessive-seat leakage. This is consistent with Specification 15.3.1.A.5.a.(2) which requires the block valve to remain shut under these circumstances, and it will preclude cycling the block valve with full system differential pressure applied.
- 2. Also in Table 15.4.1-2, Item 28, " Power Operated Relief Valves (PORVs), PORV Solenoid Air Control Valves, and Air System Check Valves," has been added as a new surveillance requirement. This requirement states those valves must be operated each refueling shutdown, and it will provide assurance that the PORVs will
NRC Document Control Desk May 30, 1991 Page 4 perform their function. Please note that the model specification contained in Generic Letter 90-06 suggested that this surveillance be completed during mode 3 or mode 4, that is at a temperature 2200*F. The elevated temperature was supposed to simulate temperature and pressure environmental effects on the ,
PORVs. When entering a refueling shutdown, however, '
there is only a short period of time in which this surveillance could be completed at the elevated .
temperature. To maximize our operational flexibility, l we have not included this temperature requirement in I our proposal.
l Please note that the model specification contained in GL 90-06 is
-written in the standardized' Technical Specification format and refers to "operaticnal modes" which are not defined in the Point Beach Technical Specifications. The model specifications require that when the operability conditions cannot be mot, the reactor must be placed in a standby condition within six hours and in a shutdown condition within the following six hours. The shutdown condition described in the model specification refers to a typical reactor coolant system temperature band of 200-350'F.
The requirement that-was contained in the model specification to cool down the reactor to 350*F within six hours after shutdown is not included in our proposal. Our proposed change to Specification 15.3.1.A.5 requires the reactor to be placed in a Hot Shutdown Condition when the requirements of the specification cannot be met. At Point Beach, Hot Shutdown is defined as a subcritical reactor with the reactor coolant temperature at or above 540'F. At Point Beach, if the reactor coolant system is cooled down below the minimum temperature for the inservice pressurization test, which is currently 360'F, the overpressure mitigation system must be-placed in service to provide overpressure relief protection for the reactor coolant system.
In this situation, since it would already be known that the overpressure mitigation system would not be functional because of inoperative PORV(s) or block valves, it would be prudent to maintain the reactor coolant system at an elevated temperature so that reactor coolant system overpressure protection would be provided by the pressurizer safety valves.
The model specification contained in GL 90-06 requires plant shutdown when a single block valve or PORV has been inoperative for. reasons other than seat leakage for a period of 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.
The-intent of.the Generic Letter is to ensure that, in the event
NRC Document Control Desk May 30, 1991
.Page 5 of a steam generator tube rupture (SGTR) accident during reactor operation, PORVs and block valves would be available to depressurize the reactor coolant system. Normally, this depressurization can be accomplished in a variety of ways including (1) the use of the normal pressurizer spray that is available when the reactor coolant pumps are running; (2) the use of the auxiliary pressurizer spray, which does not require the reactor coolant pumps but, rather, derives its flow from the charging pumps; or (3) opening the PORV and discharging steam from the pressurizer steam space. At Point Beach, normal pressurizer spray and auxiliary spray are used as the preferred means of depressurization during a S3TR; PORVs are used as the least preferred means of depressurization. In the event of a SGTR with a simultaneous failure of both the reactor coolant pumps and the charging pumps, we would open only one of the two PORVs to relieve reactor coolant system pressure. Because only one of two PORVs is required as a backup means to mitigate the SGTR accident, this proposal does not include the requirement to shut down the reactor if a single block valve or PORV is inoperative. This proposal does, however, include the i' requirement to shut down the reactor if both block valves or both PORVs are inoperative for reasons other than seat leakage.
- The model specification contained in GL 90-06 also states that a PORV is considered operable if it can operate manually and i automatically to relieve reactor coolant system pressure increases. Since automatic operation of the PORV is not required for the SGTR accident, our proposed change to the basis of Specification 15.3.1.A.5, which is in effect for reactor coolant system temperatures >360*F, states that the PORVs must operate manually.to be considered operable.- Since automatic operation of l the PORV is required for the Overpressure Mitigation System, the basis for Specification 15.3.15, which is in effect for reactor coolant system temperatures 5 360*F, states that the PORVs must operate automatically for the overpressure Mitigation System to be considered operational.
- Please also note that the model specification contained in GL 90-06 included a surveillance requirement for testing the emergency electrical power supplies to the PORVs and block valves. This requirement is discussed as follows:
A. At Point Beach the PORVs are air-operated valves. The solenoid valve that controls air to the PORV operator is powered by a DC battery charger that is in parallel with a battery.. If power is lost to the battery charger, the battery supplies uninterrupted power to the PORV control air b
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NRC Document Control Desk May 30, 1991 1 Page 6 solonoid valvo. Because the PORV control air solenoid receives a constant power supply from a battery, it is unnecessary to test the emergency power supply to the PORV, and the proposed change to our Technical Specifications does not include this test.
B. At Point Beach the block valves receive electrical power from off-site power through the 480 volt safeguard buses and L then through 480 volt motor control centers (MCCs). If off- i site power is lost, the emergency diesel generators will automatically power the 480 volt safeguard buses and, in i turn, the 480 volt MCCs that supply power to the PORVs. The
-diesel generators and the related automatic load transfer i
systems are presently tested to ensure operability; this L testing demonstrates the continuity of power to the PORVs after a loss of their normal power supply. Additional testing of emergency power supplies to block valves has not been included in the proposed change.
GL 90-06 also discussed the resolution of Generic Issue 94, j " Additional Low-Temperature Overpressure Protection for Light-Water Reactors." The resolution of this issue revealed that a low-temperature overpressure transient is most likely to occur when the reactor coolant temperature is less than or equal to 200*F. GL 90-06 mandated administrative controls for the overpressure Mitigation System (OMS) that will improve the availability of the system when the potential for an overpressure event is the highest. . Our proposed changes to specification 15.3.15 incorporate the guidance in GL 90-06 into our Technical Specifications and are discussed as follows:
.A. Specification 15.3.15, " Overpressure Mitigation System Operations," lists LCOs for the OMS that are in effect when the reactor coolant system is less than the minimum temperature for the inservice pressurization test.
Currently,-when the reactor coolant temperature is less than 360*F, a PORV can be inoperable for up to seven days before the reactor coolant system must be opened to atmosphere. In j the change proposed to Specification 15.3.15.A.2, when
! reactor coolant temperature is less than or equal to 200*F, a PORV can be inoperable for a total of only 32 hours3.703704e-4 days <br />0.00889 hours <br />5.291005e-5 weeks <br />1.2176e-5 months <br /> before the reactor coolant system must be opened to atmosphere.
B.- Our proposed change also includes the addition of a new LCO, 15.3.15.A.3, that states that when the reactor coolant system is open to atmosphere because of an inoperable PORV,
- the vent pathway must-be verified on a periodic basis. When the pathway is provided by a non-isolable atmosphere pathway or by a valve (s) that is locked, scaled, or otherwise I
. l 1
NRC Document Control Desk May 30, 1991 Page 7 secured in position, the pathway must be verified overy 31 days; otherwise,
-hours.
the pathway must be verified overy 12 C. Specification 15.3.15 currently states that when PORVs are inoperable, the reactor coolant system must be vented to the pressurizer relief tank. The' proposed change states that when PORVs are inoperable, the reactor coolant system must be opened to atmosphere. In the basis of Specification 15.3.15, the term "open to atmosphere" has been defined as an opening in the reactor coolant system pressure boundary that will relieve system-pressure. Examples ci these openings include PORVs that are open to the pressurizer relief tank, open steam generator manways, and the top of the reactor removed or vessel when the reactor vessel head has been unbolted. This change has been included in the proposal because the tena "open to atmost iere" was not previously defined and because there are several acceptable ways to vent the reactor coolant system.
In its discussion of Generic Issue 14, GL 90-06 mandated a change to surveillance requirements involving the OMS. -In our proposal, an openBlock "PORV position checkinofTable Valves," block15.4.1-2.
valves has been added to Item 23, This check is required only when the OMS is in operation, and it will ensure that the PORVs have a flow path available to relieve reactor coolant system. pressure.
Please note that the proposed change includes two administrative changes that have been included to improve the clarity of specifications pertaining to the OMS. The proposed changes are discussed-as follows:
A. Specification 15.3.15.A.1.b is an operability requirement that currently states, "The upstream isolation valves to both-power-operated-relief valves are open." The proposed change rewords this statement stating, "Both power operated relief block valves are open." This is an administrative change that will make the statement more understandable to the users of the specification, but it does not change the meaning of the specification.
B. In Table 15.4.1-1, " Minimum Frequencies for Checks, Calibrations, and Test of Instrument Channels," surveillance requirement Item 29, " Overpressure Mitigation," requires the overpressure mitigation system instrument channel to be checked once per shift.
A remarx has been added to indicate
-that this check is required only when the OMS is in
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NRC Document Control Desk May 30, 1991 Page 8 operation. This remark clarifies Item 29 but does not change the frequency of the checks because we do not currently perform these instrument channel checks when the OMS is not in use.
In accordance with the requirements of 10 CFR 50.91(a), we have evaluated these changes against the standards in 10 CFR 50.92 and have determined that the operation of the Point Deach Nuclear Plant units in accordance with the proposed amendments does not present a significant hazards consideration. A proposed amendment involves no significant hazards consideration if operation of the facility in accordance with the proposed amendment would not (1) involve a significant increase in the probability or consequences of an accident previously evaluated, (2) create the possibility.of a new or different kind of accident from any accident previously evaluated, or (3) involve a significant reduction in a margin of safety.
In regards_to Specification 15.3.1.A.5, " Pressurizer Power-Operated Relief Valve (PORV) and PORV Block Valves," the proposed change requires no physical change to the facility or its systems,_but it does require changes to operating procedures.
The proposed changes to Technical Specifications specify electrical power supply requirements to PORVs and block valves while they are inoperable. -These changes minimize the potential for-the loss of reactor coolant through a PORV or block valve when either is inoperable. The changes also provide operators the procedural flexibility to be able to relieve excessive reactor coolant system pressure when these valves are inoperable.
These changes have been made in accordance with the guidance in GL 90-06.
l l Because the PORV system is not being physically changed, I
previously_ analyzed accidents are not adversely affected.
Similarly,uan increased probability or consequences of an accident-previously_ evaluated cannot result. Because the proposed changes do not alter the function of existing systems, but do enhance the reliability of those systems, a new or different kind of accident from any previously evaluated cannot result.
Specification 15.3.0, " Limiting conditions of Operation,"
requires us to place the plant in the shutdown condition within three hours after discovering a situation that is not specified as a permissible condition of an LCO. Since our Technical Specifications do not currently address situations in which two PORVs or two block valves are inoperable, in both cases we are required to shut down the affected unit within three hours. For two inoperable PORVs or block valves, our proposed change allows one hour to restore the first valve; otherwise the unit must be
l NRC Document Control Desk May 30, 1991 Page 9-shut down in the following six hours. This new time limit has been established in accordance with the guidelines of GL 90-06, and it is an' aggressive limit that ensures that the plant will be kept in a safe condition. The new limit extends the amount of time allowed to restore the first valve to one hour and the amount of time for plant shutdown to six hours. The extension of the time limits results hacause the situation was not previously addressed. The margin of safety, therefore, is at most only minimally reduced from present levels.
In regards to Table 15.4.1-2 " Minimum Frequencies for Equipment and Sampling Tests," the proposed change requires no physical change to the facility or systems, but does require changes to operating procedures. The proposed change requires that PORVs be cycled every refueling shutdown. Additionally, PORV operating solenoid air control valves and check valves on associated air systems must also be cycled each refualing shutdown. Such surveillance requirements do not increase the probability or consequences of previously evaluated accidents, and they will not create the possibility of a new or different accident. Because the actions contained in these surveillance requirements provide assurance that the-PORVs can perform their function, there is actually an incrvase in the margin of safety by providing additional assurance that the failure of an inoperab'e PORV will not result in a loss of reactor coolant.
The proposal eliminates the requirement to cycle a block valve that has been shut to isolate a PORV that is inoperable for reasons other than excessive seat-leakage. Opening the block valve under these conditions is prohibited by Specification 15.3.1.A.5.a.(2). Failure to cycle the block valves while in this condition will not increase the probability or consequences of previously evaluated accidents, and it will not create the possibility of any new or different accidents. If the block valves are not cycled, there may be a minimal reduccion in the margin of safety because the operability of the block valves would be unknown. Conversely, maintaining the block valves in the. closed position.while the PORV is inoperable would result in an increase in the margin of safety.
The proposal also includes a position check of block valves when the OMS is in operation. This check is a verification of proper system lineup. It does not affect the likelihood or severity of any accidents. Since the check does not alter the function of existing systems, a new or different kind of accident from any previously evaluated cannot result, and there is no reduction in the margin of safety.
HRC Document Control Desk Jay 30, 1991 ago 10 In regards to Specification 15.3.15. "ovorpressure Mitigating Systems operations," the proposed change requires no physical change to the facility or its systems, but it does require changes to operating proceduros. The proposed change reducos, from 7 days to 32 hours3.703704e-4 days <br />0.00889 hours <br />5.291005e-5 weeks <br />1.2176e-5 months <br />, the time allowed to open the reactor coolant system to atmosph9re, when a poRV is inoperable and when the reactor coolant temperature is s200*F. These are administrativo changos that will put the facility in a safer condition when the poRVs are inoperable, thus reducing the likelihood of cecidents. The proposed change also requires that i when the reactor coolant system is open to atmosphoro because of i an inoperable poRV, the vont path lineup must be checked periodically. Because this check is moroly a verification that i tho vont pathway exists, it would not affect the likelihood or severity of any accidents. Since the proposed changes do not alter the-function of existing systems but do onhance the reliability of those systems, a now or different kind of accident from any previously evaluated cannot result and there is no reduction in the margin of safety. In fact, for $200*F the requirement to vont the reactor coolant system within 32 hours3.703704e-4 days <br />0.00889 hours <br />5.291005e-5 weeks <br />1.2176e-5 months <br /> when a poF.V is inoperable will increano the margin of safety.
Specification 15.3.15 currently states that the reactor coolant system must be vented to the proscurizar rolior tank when the OMS is not functional. Our proposed change requires the reactor coolant system to be opened to atmosphere when the 0MS is not functional. The term "open to atmosphorn" is defined in the baals to includo openings such as PORVs that are open to the pressurizer relief tank, open steam generator manways, and the top of the reactor vessel when the reactor vessel head has been unbolted or removed. This change was mado because thoto are several different ways to adoquately vont the reactor coolant system to atmosphere. It does not affect the likelihood or severity of any accidents, and thero is no reduction in the margin of safety.
The proposed change also includes administrative wording changes portaining to the OMS. Technical Specification 15.3.15.A.1.b has boon reworded so that it is moro understandable. Additionally, in Table 15.4.1-1 a remark has boon added to Item 19 stating that the overpressure mitigation system instrument channel checks need be conducted only-when the system is in operation. Thoso changes have boon proposed to clarify the wording of the portinent sections. The changes do not change the meaning or intent of the specifications or current operational proceduros. Thoso changos, therefore, have no offect on existing or unovaluated accidents, and the margin of safety is not affected.
l
, 4 NRC Document Control Desk May 30, 1991 Page 11 We have provided the proposed Technical specification changes in I accordance the direction of GL 90-06. Our time table for implementation of these changes is not dependent on a unit outage. Accordingly, we have not specified a date by which these license amendments should be issued. We would be pleased to answer any questions you may have concerning those changes.
Very truly yours, h(t/- l Pay)/
C. W. l Vice President Nuclear Power Enclosures ;
1 Copies to NRC Regional Administrator NRC Resident Inspector i i
subscribed and sworn to before me this & M day of h\ c._ s ,1991.
/
L p_- n %J 1. w1n <
Notary Public, State of Wisconsin My Commission expires f_ '} 4 .
1
15.3.1.A.5. Pressurizer Power-Operated Rolief Valves (PORV) and PORV Block Valves
44-) I-f-a-PORV-le-i nope ra b le-d u e-to-l ea k a g e-i n-ow oeo s o f-t ha t-e14cwed-i n-6 peci f4 ca t4 o n-15r3 rl,rDr-t h e PORV-oh a44-be-re o to red-t o-o n-ope ra bl e-oo nd i bl on within-ene-hour-or-the-eseoolated-block-valve sha14-be-olosedt
'(1) ~ 'If o'ne or'both PORVs'are INOPERABLE due to seat Jenkage in. excess.of'that allowed in Specifications 15.3.1.D;,;within one' hour either restore the PORVs to an operable status;or close the associated block valves (s) with power maintained to'~ the block valve (s) . , If.theac conditions'cannot'be met, place the unit in a HOT SHUTDOWN condition within the next six hours.
(2) !-f-a-PORV-le-i nope ra bl e-d u e-to-e-oha n nel-f u no-t-lona4-test-fa44ure -the-assoolated-POHV--control r
owl beh-sha44-be-pleoed-a nd-ma4 n to 1 ned-in-t he closed-position-or-the-easooisted-block-valve s ha14-be-elesed-w i-t h i n-one-h ou er
~ '
(2) '
If"one PORV is INOPERABLE dueto causos.other than
excessive seat leakage, within one. hour either restore the PORV.to-OPERABLE' status or close.Its sesociated block valve and remove t power from the block' valve. If-this condition'cannot be-met; placcithe[ unit:in a HOT SHUTDOWN conditf.on within
' ' "'~
the!next sixLhours.
(3) LIf?both PORVs are" INOPERABLE dde'tofcau'sesTother than' excessive seat leakage, within<one; hour restore'at least<one.PORV.to OPERABLE status ~.? ;-I f this condition;cannot1.be; met,fclose the associated block valves-with power. removed-from-the~ block ~
valves and place-tho'unitiin~a HOT SHUTDOWN
~
condition within the next six' hours;
- 44) 'cf-e-POW-block-valve-ie-inoperabley-the-block velve-s h el4-be-res to red-to-a n-ope ra ble-condi t4 on with4-n-o ne-hou r-o m e-blook-va lve-s h a 44-be -o l oned with-power-removed-frem-the-block-valvet otherwiee r-the-unit-sha44-be-in-shutdown-wIthin the-new t-elw-hourer If>one' block; valve 11s/ inoperable;"withir-one' hour
'( 4 ) '"~ oither restore theLblock valvo(s)'to OPERABLE status or place:the associated:PORVJin manual
control. If this condition'cannot be' mot z, place the unit in a HOT S11UTDOWN condition withan the next six hours.
(5) ~
'If both~ block valves are inoperable, restore at least one block valve to OPERABLE status within one hour. If-this condition cannot.be met, place the associated PORVs in manual contro11and place the unit in a llOT S110TDOWN condition within the next six hours.
BASIS A PORV in defined as OPERABLE if leakage past the valve in less than that allowed in Specification 15.3.1.D and the PORV-has met-i to-mos t-recent-cha n nel-tent-e a-speo i-f led -i n-Te ble-1 Gr4rl-1 r The-PORVe-operate-to-rel4 eve r -in-a-contro14ed-eannerr-reactor coole n t-e y a tem-p ress u re-i n e res se e-below-t h e-se t t4 ng-o f-t he pressur4eer-eafety-va bec. Theso-PORVe-have-remotely-operated blook-valves-to-prov hi e-e-pon i t49e-shu to f f-ca pa bi44 ty-shou 1 d-e PORV-become-inopera bler- most recent associated channel test, as specified in Table 15.4.1-1, is acceptable. . Additionally, the PORV must have the capability of' operating manually to relieve reactor coolant system coolant-pressure increases.
A block valve is defined asLOPERABLE if the valve ~can
'perate o manually'and if it can control identified PORV leakago.
When a'PORV is INOPERABLE due to excessive seat leakage, the block valve.is shut with power maintained to-the block valve.no that the-block . valve (s) is readily available and may be used to allow the PORV to control reactor pressura. Excessive primary system leakage is defined-in specification.15.3.1.D. The block valve may romain shut to isolate the11eaking PORV for a. limited period of' time not to exceed.the next refueling shutdown. .When a PORV'is' INOPERABLE-for reasons other than excessive scat-leakage, tho block valvelis shut with power removed; this, precludes any '
~
inadvertent opening of .the block valve.:
When a block valve is IHOPERABLE, the"; associated ' PORVTi's placed.in manual control; this precludes the undesired automatic opening.of the.PORV.
i 15.3.15 OVERPRESSURE MITIGATING SYSTEM OPERATIONS Aonlicability Applists to operability of the overpressure mitigating system when the reactor coolant system temperature is less than the minimum temperature for the inservice pressure test.
Qhigetive To specify functional requirements and limiting conditions for operation on thg use of the pressurizer power operated relief valves when used as part of the overpressure mitigating system and to specify further limiting conditions for operation when the reactor coolant system is operated without a pressure abgorbing volyme in the pressurizer.
Specification A. System operability
- 1. Except as specified in 15.3.15.A.2 below, the overpressurization mitigating system shall be operable whenever the reactor coolant system is not open to the atmosphere and the temperature is less than the minimum ..
pressurization temperature for the inservice pressure test, as specified in Figure 15.3.1-1. Operability requirements aret.
- a. Both pressurizer power operated relief valves operable at a setpoint of $425 psig.
- b. The-up s t r ea m-4ee le trien-v al v es--to-bo th- powe r opera t ed -- r c 14ef-valvee-a re-open .
h--Thc requireneato-ef-15. 3.1&rArl-may 4: mod 1-f4ed-te e4-Icw- cne of-the-two pcucr-- Operated-rel4ef-valves-to-be 4noperable-f+r --perded-of-not-more-ther. - OcVe n - dayer--
- 3. I f-t he-inopera bl e-power-epe ra ted-rel4 s f-valves-oa nnot be-made cperable-within-eeven-dayer-the-reeotor-coolent ayetem-must=be depressue4 med-and vcnted-to-t-he pressuel-m er-rel4 ef-tenk-w it hi n-eigh t-hou rs .
b.f jBothspoVer operatedLreli~ef[ valve'blocF valvesfare 2 '. 4 "The
- r u ements?of(1513115fL17mayJbe7modifiedfas
' specified,below:
. a ." - With' ~ one : PORV?inoperableiwhi1Fre'actoWoolant system; temperature is ?200*F4butilesaithainthe ulnimum pressurization?temperaturesfor?the^
inservi~ce: pressure: test,'either; restore the inoperable:PORV to" operable _ status within57Fdisysp or depressurize: reactor 7coolantisystemtto~
atmosphere Withintthe:next 8; hours.
b~. 1With;one!PORVfinopt:.rable' while reactorf coolant-wystem1temperaturefis75200*FKeitherures. tope 3We inoperable PORV to operableEstatus?withi hours,for depressurise-the1 reactor;coole nO $241system toithe} atmosphere withinka1totaliofj2hhours..
- 4. M-both~% r4pe ra tedee l4e f4a4 ves-a r&lnope ro biky the-react +r-coolen t-sys t+m-must-be-deprespu el med-an d vented-to-the-p resau el z e r- r c 14ef-t-a nk-wit h i n-eigh t houco.
I c1 ; WithTbothi p6werJ' operated? relief fvalVeWinopeiltblo l
i l
1
(
l.*
While the reactor coolant Mystem temperature is less than the minimum; pressurization temperature
~
for the inservice pressure test, the reactor coolant system must be depressurized-and opened to
^
the atmosphere within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />.
- 3. If the reactor coolant system is open'to'atmosphoro per Specification 15.3.15.A.2.a, b, or c, the atmosphere pathway must be verified at least onco every 31 days when it is provided by a non-isolable-atmosphere pathway or by a valve (s) that is locked, coaled , or otherwise' secured in the'open position; otherwise, verify the atmosphere pathway overy 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.-
B. Additional Limitations
- 1. When the reactor coolant system is not open to the atmosphore and the temperature of one or both reactor coolant system cold Icgs is $275*P, no more than one high pressure safety injection pump shall bo operable.
The second high pressure safety injection pump shall be demonstrated inoperable whenever the temperature of one or both reactor coolant system cold legs is $275'F by verifying that the motor circuit breakors havo been removed from their electrical power supply circuits or by verifying that the dischargo valves from the high pressure safety injection pumps to the reactor coolant system are shut and that power is removed from their operators.
- 2. A reactor coolant pump shall not be started when the reactor coolant system temperature is less than the minimum temperature for the inservico pressure test unless:
- a. There is a pressure absorbing volume in the pressurizer or in the steam generator tubes or
- b. The secondary water temperature of each steam generator is less than 50'F above the temperature of the reactor coolant system.
Dania The Overpressurization Mitigating System consists of a diverse means of relieving pressure during periods of water solid operation and when the system temperature is below the value permitted to perform the primary system leak test. This method of water relief utilizes the pressurizer power oporated relief valves (PORV's). The PORV's are made operational for low pressure relief by utilizing a dual set-point where the low pressure circuit is energized and do-onergized by the operator with a keylock switch depending on plant conditions. The logic required for the low pressure sotpoint is in addition to the existing PORV actuation logic and will not interfere with existing automatic or manual actuation of the pORV's. ~ The OPERABILITY"gi the'PORVs'is determined"on the basis of their being capable of' automatically mitigating an-overpressure event during low temperature operation.
l
During plant cooldown prior to reducing reactor coolant system temperature below the minimum temperature allowable for the inservice pressure test, the operator under administrative procedures shall place the keylock switch in the " Low Pressure" position. This action enables the Overpressure Mitigating System. The redundant PORY channels shall remain enabled and operable while the-reactor-coolant-eyotem-le-not-open-to-the a t mos phere-a nd-the-tempera t u re-le-l eoa-tha n-t he-m i n i mu m presou r4 e a t i on-tempera tu re-for-t he-i nse rv ice-pressu re-tes t7 except-t ha t-o n e-PORV- ma y-be-ou t-o f-se r v loo-for-e-pe ri od-o f--u p-t o seven-dayer the Overpressure Mitigation System is required to be in operation.
~
The reactor. coolant system imidefined a's open to the atmosphereJifLthere is'an-opening in the reactor. coolant system pressure boundary that will' relieve system pressure.-Some examples ofisuch openings include PORVs thatiare open to the pressurizer" relief. tank, open' steam generator manways, and the top ofsthe reactorfvessel when the-reactor vessel head'has been unbolted or removed.
The mass input transient used to det. mine the PORY setpoint assumed a worse case transient of a single high pressure safety injection pump discharging to the reactor coolant system while the system is solid. Therefore, when the reactor coolant system is less than 275'F, only one high pressure safety injection pump shall be operable at any time except when the reactor coolant system is open to the atmosphere.
The heat input transient used to determine the PORV setpoint assumes a temperature difference betwoon the reactor coo 317t system and the steam generator of 50*F. Thorofore, beforo starting a reactor coolant pump when the reactor coolant system is solid, the operator shall insure that the secondary temperature of each steam generator is less than 50'F above the temperature of the reactor coolant system unless a precsure absorbing volume has been verified to exist in the pressurizer or steam generator tubes.