ML18153A699
| ML18153A699 | |
| Person / Time | |
|---|---|
| Site: | Surry  |
| Issue date: | 07/14/1995 |
| From: | VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.) |
| To: | |
| Shared Package | |
| ML18153A698 | List: |
| References | |
| NUDOCS 9507180178 | |
| Download: ML18153A699 (9) | |
Text
TS 3.1-2
- b. If an unscheduled loss of one or more reactor coolant pumps occurs while operating below 10% RATED POWER (P-7) and 1 results in less than two pumps in service, the affected plant shall be shutdown and the reactor made subcritical by inserting all control banks into the core. The shutdown rods may remain withdrawn.
- c. When the average reactor coolant loop temperature is greater than 350°F, the following conditions shall be met:
- 1. At least two reactor coolant loops shall be OPERABLE.
- 2. At least one reactor coolant loop shall be in operation.
- d. When the average reactor coolant loop temperature is less than or equal to 350°F, the following conditions shall be met:
- 1. A minimum of two non-isolated loops, consisting of any combination of reactor coolant loops or residual heat removal loops, shall be OPERABLE, except as specified J below:
(a) One RHR loop may be inoperable for up to 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> for surveillance testing provided the other RHR loop is OPERABLE and in operation.
(b) During REFUELING OPERATIONS the residual heat removal loop may be removed from operation as specified in TS 3.10.A.6.
- 2. At least one reactor coolant loop or one residual heat removal loop shall be in operation, except as specified in Specification 3.1 O.A.6.
Amendment Nos.
9507180178 950714 PDR ADOCK 05000280 P PDR
- TS 3.1-23 G. Reactor Coolant System Overpressure Mitigation Specification
- 1. The Reactor Coolant System (RCS) overpressure mitigating system shall be OPERABLE as described below:
- a. Whenever the RCS average temperature is greater than 350°F, a bubble shall exist in the pressurizer with the necessary sprays and heaters OPERABLE.
- b. Prior to decreasing RCS average temperature below 350°F, verify a maximum of one charging pump is capable of injecting into the RCS and that each accumulator is isolated. Thereafter, once per 12 hour1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />s:
(1) Verify that a maximum of one charging pump is capable of injecting into the RCS.
- (2) Verify that each accumulator is isolated, if isolation is required.
- c. Whenever the RCS average temperature is less than or equal to I 350°F and the reactor vessel head is bolted:
(1) A maximum of on~ charging pump shall be OPERABLE and capable of injecting into the RCS. Two charging pumps may be in operation momentarily during transfer of operation from one charging pump to another.
and (2) The accumulators shall be isolated (accumulator discharge valves closed and their respective breakers locked, sealed or otherwise secured in the open position). Isolation is not required if the accumulator pressure is less than the pressurizer PORV setpoint specified in TS 3.1.G.1.c.(4).
and Amendment Nos.
e TS 3.1-23a (3) During the initial 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />, maintain a bubble in the pressurizer with a maximum narrow range level of 33%,
or (4) Maintain two Power Operated Relief Valves (PORV)
OPERABLE with a lift setting of ::::; 385 psig and verify each PORV block valve is open at least once per 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />, or (5) The RCS shall be vented through one open PORV or anequivalent size opening as specified below:
(a) with the RCS vented through an unlocked open vent path, verify the path is open at least once per 12 I hours, or (b) with the RCS vented through a locked open vent path verify the path is open at least once per 31 days.
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- 2. The requirements of Specification 3.1.G.1.b(4) may be modified as follows:
(a) One PORV may be inoperable in INTERMEDIATE SHUTDOWN with the RCS average temperature > 200°F but < 350°F for a period not to exceed 7 days. If the inoperable PORV is not restored to OPERABLE status within 7 days, then completely depressurize the RCS and vent through one open PORV or an equivalent size opening within the next 8 hou*rs.
(b) One PORV may be inoperable in COLD SHUTDOWN or REFUELING SHUTDOWN with the reactor vessel head bolted for a period not to exceed 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. If the inoperable PORV is not restored to OPERABLE status within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> then completely depressurize the RCS and vent through one open PORV or an equivalent size opening within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />.
Amendment Nos.
TS 3.1-24
- c. With both PORV's inoperable, depressurize the RCS within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> unless Specification 3.1.G.1.b.(4) is in effect. When the RCS has been depressurized, vent the RCS through one open PORV or an equivalent sized opening, or establish the conditions listed below. Maintain the RCS depressurized until both PORV's have been restored to OPERABLE status.
(1) A maximum pressurizer narrow range level of 33%.
(2) The series RHR inlet valves open and their respective breakers locked open or an alternate letdown path OPERABLE.
(3) A maximum of one charging pump is capable of injecting into the RCS.
(4) Safety Injection Accumulator discharge valves closed and their respective breakers locked, sealed, or otherwise I secured in the open position.
- d. When the conditions noted in 3.1.G.2.c.(1) through 3.1.G.2.c.(4) above are required to be established, verify the required conditions are met at least once per 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.
- 3. In the event that the Reactor Coolant System Overpressure Mitigating System is used to mitigate a RCS pressure transient, a Special Report shall be prepared and submitted to the Commission pursuant to Specification 6.6 within 30 days. The report shall describe the circumstances initiating the transient, the effect of the mitigating system or the administrative controls on the transient and any corrective actions necessary to prevent recurrence.
Basis The operability of two PORV's or the RCS vented through an opened PORV ensures that the Reactor Vessel will be protected from pressure transients which could exceed the limits of Appendix G to 10 CFR Part 50 when the Reactor Coolant Stem average temperature is < 350°F and the Reactor Vessel Head is bolted. When the Reactor Coolant System average temperature is > 350°F, overpressure protection is provided Amendment Nos.
e e TS 3.1-25 by a bubble in the pressurizer and/or pressurizer safety valves. A single PORV has adequate relieving capability to protect the Reactor Vessel from overpressurization when the transient is limited to either (1) the start of an idle Reactor Coolant Pump with the secondary water temperature of a steam generator ::;; 50°F above the RCS cold leg temperature or (2) the start of a charging pump and its injection into a water solid RCS.
The limitation for a maximum of one charging pump allowed operable and the surveillance required to verify that two charging pumps to be inoperable below 350°F provides assurance that a mass addition pressure transient can be relieved by the operation of a single PORV, or equivalent. The Safety Injection accumulators are not considered a credible mass input mechanism for RCS low temperature overpressurization concerns. There are administrative controls to ensure isolation, including de-energizing the Safety Injection (SI) accumulator isolation valves, during plant shutdown conditions (RCS pressure less than 1000 psig) to prevent inadvertent SI accumulator discharge into the RCS for low temperature overpressurization concerns. An undesired pressurizer PORV lift due to inadvertent SI accumulator discharge is not possible when SI accumulator pressure is less than the low temperature PORV lift setpoint specified in TS 3.1.G. Therefore, SI accumulator isolation, and verification of such isolation is not necessary when SI accumulator pressure is less than the low temperature PORV setpoint.
A maximum pressurizer narrow range level of 33% has been selected to provide sufficient time, approximately 1O minutes, for operator response in case of a malfunction resulting in maximum charging flow from one charging pump (600 gpm). Operator action would be initiated by at least two alarms that would occur between the normal operating level and the maximum allowable level (33%). When both PORV are inoperable and it is impossible to manually open at least one PORV, additional administrative controls shall be implemented to prevent a pressure transient that would exceed the limits of Appendix G to 10 CFR Part 50.
The requirements of this specification are only applicable when the Reactor Vessel head is bolted. When the Reactor Vessel head is unbolted, a RCS pressure of < 100 psig will lift the head, thereby creating a relieving capability equivalent to at least one PORV.
Amendment Nos.
e Attachment 3 Significant Hazards Consideration Determination Surry Power Station
e 10' CFR 50.92 SIGNIFICANT HAZARDS CONSIDERATION REVIEW Virginia Electric and Power Company has reviewed the proposed Technical Specifications change against the criteria of 10 CFR 50.92 and has concluded that the Technical Specifications change as proposed does not pose a significant hazards consideration. The proposed Technical Specification change will provide a two hour allowed outage time for one RHR pump to accommodate plant surveillance testing.
This change is consistent with NUREG-1431, Standard Technical Specifications For Westinghouse Plants, dated April 1995. In addition, the proposed change permits depressurizing the accumulator when the RCS pressure is less than the Low Temperature Overpressure Protection System (LTOPS) setpoint (385 psig) in lieu of accumulator isolation. Specifically, operation of the Surry Power Station in accordance with the proposed change will not:
(1) Involve a significant increase in the probability or consequences of an accident previously evaluated.
Surveillance and testing requirements are necessary to assure that RHR and interfacing systems' reliability is maintained. Existing analyses demonstrate that adequate shutdown cooling will be maintained with one train of RHR Operable and in service. Analyses also demonstrate that alternate shutdown cooling modes remain available with adequate decay heat removal capability.
Furthermore, the opposite train of RHR remains available while in the two hour surveillance AOT. The response time and operator actions required to place the available RHR train in service are consistent with similar operator response times and actions required to place alternate shutdown cooling modes in service. The administrative controls and procedures in place assure adequate shutdown cooling capability is maintained as supported by existing analyses.
The existing safety analyses demonstrate that Reactor Coolant System integrity will be maintained when SI accumulator pressure is below the pressurizer PORV LTOPS setpoint. Therefore, SI accumulator isolation is not required to ensure Reactor Coolant System integrity. With RCS temperature below the LTOPS enabling temperature, automatic actuation of the pressurizer PORVs or other TS specified relief paths ensure the assumed design basis reactor vessel beltline flaw will not propagate under design basis low temperature overpressurization accident conditions. System design and configuration adequately mitigate an LTOPS actuation due to an SI accumulator discharge with no negative consequences regarding RCS structural integrity or SBLOCA concerns.
Therefore, the proposed Allowed Outage Time for an inoperable RHR loop and the ability to depressurize the SI accumulator in lieu of SI accumulator isolation do not increase the probability or consequence of any previously analyzed accidents.
(2) Create the possibility of a new or different kind of accident from any previously evaluated.
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e e The proposed two hour AOT for one train of the RHR System will preclude the possibility of a Technical Specification violation for conditions where a train of RHR is out of service for surveillance testing. Calculations by Westinghouse with evaluations and supporting analyses performed by Virginia Power, confirm the adequacy of decay heat removal with one RHR train in service, and multiple alternate shutdown cooling modes remain available. There are no plant modifications required by this proposed TS change. Further, the proposed change does not invalidate any component design criteria or the assumptions of the UFSAR accident analyses. The RHR System is being operated in a manner consistent with the design basis and configuration of the system and is supported by existing analyses and procedural controls.
There are no new failure modes or mechanisms associated with the proposed change to allow the depressurizing of a SI accumulator to a pressure value below the LTOPS setpoint. The LTOPS enabling temperature remains unchanged. No operating limits or setpoints are added or deleted by the proposed change. Reactor Coolant System pressure relief paths are not affected.
Therefore, the possibility of a new or different kind of accident is not being created by the proposed Allowed Outage Time for an inoperable RHR loop and the ability to depressurize the SI accumulator in lieu of SI accumulator isolation.
(3) Involve a significant reduction in margin of safety.
The proposed Technical Specifications change does not involve a reduction in a margin of safety. The existing safety analyses demonstrate that adequate shutdown cooling will be maintained when a train of RHR is out of service for up to two hours for plant system surveillance testing, while the operable train of RHR is operating. Supporting analyses determined that the RHR System meets the design cooldown requirements for a reactor core rating of 2546 MWth with either one or both trains of RHR in service. Additionally, an evaluation of the technical basis for shutdown operations for the proposed Surry core uprating to 2546 MWth determined that the administrative controls and Abnormal Procedures in place at Surry ensure adequate decay heat removal capability during shutdown conditions. The administrative controls and procedure revisions are supported by a detailed series of thermal-hydraulic calculations for various loss of RHR scenarios. There is no reduction in shutdown cooling capability due to the proposed TS change, and no reduction in the capability to mitigate a loss of decay heat removal event since the RHR train affected by the testing is available and can be restored in a comparable time period to that required to restore RHR to service in the event of loss of station power or loss of the operating train of RHR.
Consequently, system design, plant configuration, and administrative controls remain available to adequately mitigate a loss of RHR event with a single train of RHR out of service for up to two hours during plant system surveillance 2
testing. It may be concluded that there is no reduction in the margin of safety due to the proposed Technical Specification change.
Existing safety analyses also demonstrate that Reactor Coolant system integrity will be maintained in the event of an inadvertent SI accumulator discharge when SI accumulator pressure is below the pressurizer PORV LTOPS setpoint. Sufficient administrative controls are maintained to ensure LTOPS is "Enabled" and SI accumulators are isolated at the appropriate RCS conditions to minimize the possibility of challenging RCS integrity. Technical Specifications administrative controls that prevent inadvertent charging pump operation, maintain adequate relief paths, and restrict Steam Generator primary to secondary temperature differential remain in place. Consequently, the Technical Specifications change ensures that an inadvertent SI accumulator discharge cannot challenge RCS structural integrity during LTOPS conditions when SI accumulator pressure is below the pressurizer PORV LTOPS setpoint.
Therefore, the proposed Allowed Outage Time for an inoperable RHR loop and the ability to depressurize the SI accumulator in lieu of SI accumulator isolation does not reduce any margin of safety as defined in the Technical Specifications.
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