ML17164A497
| ML17164A497 | |
| Person / Time | |
|---|---|
| Site: | Susquehanna  |
| Issue date: | 12/20/1994 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML17164A496 | List: |
| References | |
| NUDOCS 9501050334 | |
| Download: ML17164A497 (7) | |
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UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20M&0001 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT N0.136TO FACILITY OPERATING LICENSE NO. NPF-14 AMENDMENT NO. 106 TO FACILITY OPERATING LICENSE NO. NPF-22 PENNSYLVANIA POWER 8L LIGHT COMPANY ALLEGHENY ELECTRIC COOPERATIVE INC.
SUS UEHANNA STEAM ELECTRIC STATION UNITS 1
AND 2 DOCKET NOS. 50-387 AND 388
- 1. 0 INTRODUCTION By letter dated July 19,
- 1994, Pennsylvania Power 8 Light Company (PPSL or the licensee) submitted a request to amend the Techni.cal Specifications for Susquehanna Units 1 and 2.
The proposed Technical Specification change involves the requirement for operability of the Standby Liquid Control (SLC);
system in operational condition 5 with any control rod withdrawn and the surveillance requirements for the SLC system tank heaters.
The current Technical Specification (TS) 3. 1.5 for Susquehanna Units 1 and 2
requires that the SLC systems be operable during operational condition 5 with any control rod withdrawn (OPCON 5 ).
The current TS also requires an operability check on the SLC system tank heaters every 18 months per Surveillance Requirement
- 4. 1.5.d.3.
The licensee has proposed to delete both the requirement for SLC system operability during OPCON 5
and the 18-month surveillance requirement for the SLC system tank heaters.
The staff has reviewed this proposed TS change and our evaluation follows.
- 2. 0 EVALUATION 2.1 SLC System Operability in OPCON 5*
The purpose of the SLC system is to provide a backup means to shutdown the reactor from full power to a cold, xenon-free shutdown condition, assuming that none of the withdrawn control rods can be inserted.
General Design Criteria (GDC) 26 and 27 contain guidance for the purpose and capability of the SLC system.
GDC 26 discusses reactivity control system redundancy and capability.
It states that two independent systems shall be provided, and that one of the systems shall be capable of holding the reactor core subcritical under cold conditions.
Compliance with this design criteria is accomplished for Susquehanna with the control rod system and the reactor recirculation system.
The control rod system has the capability to maintain the reactor subcritical under cold conditions regardless of the reactor water level assuming that the 9501050334 941220 PDR ADOCK 05000387 P
highest worth control rod is withdrawn from the core.
In the event that additional control rods were withdrawn, the reactor protection system,(RPS) would respond and insert all control rods prior to reaching criticality.
During OPCON 5*, the RPS monitors recriticality with source range monitors (SRMs), intermediate range monitors (IRHs) and average power range monitors (APRHs).
GDC 27 discusses combined reactivity control system capability.
The criteria states that the reactivity control systems shall be designed to have a combined capability, in conjunction with poison addition by the emergency core cooling system, of reliably controlling reactivity changes to assure that under postulated accident conditions and with the appropriate margin for stuck rods, the capability to cool the core is maintained.
However, the Susquehanna Final iSafety Analysis Report Section 3. 1.2.3.8, which discusses design conformance to GDC 27, states that there is no credible event applicable to the BWR which requires combined capability of the control rod system and poison additions by the emergency core cooling network.
The primary reactivity control system for the BWR during postulated accident conditions is the control rod system.
In the event that more than one control rods fails to
- insert, and the core cannot be maintained in a subcritical condition by control rods alone as the reactor is cooled subsequent to initial shutdown, the SLC system will be actuated to insert soluble boron into the reactor core to achieve and maintain a subcritical condition.
This scenario is anticipated transient without scram (ATWS).
The function described above for the SLC
Pursuant to 10 CFR 50.62, requirements are provided for reduction of risk from ATWS events for light-water-cooled nuclear power plants.
It is required by 50.62(c)(4) that each boiling water reactor must have an SLC system, and provide requirements for the design of the SLC system.
The SLC system at Susquehanna meets this regulatory requirement.
Operability of the SLC system in OPCON 5* is not required for Susquehanna to meet their licensing basis.
In OPCON 5, adequate shutdown margin (SDH) and redundancy are maintained by systems and control independent of the SLC system.
Adequate SDM is maintained during OPCON 5
through design and administrative control.
In addition, the RPS monitors for recriticality and scrams the reactor before a return to criticality.
There are four conditions during OPCON 5* which involve SDM:
(1) the shutdown phase prior to core offload; (2) core off-loading; (3) core reloading; and (4) full core reloaded.
During the first condition, adequate SDH is assured via the SDH demonstration which was performed when the core was loaded.
During core off-loading, adequate SDH is maintained or increased as required by TS 3. 1.1 and implemented through procedural controls.
Fuel movement and other core alterations with control rods removed from the core are controlled by TS Section 3/4.9, Refueling Operations.
Prior to core
- reload, SDM is determined analytically, and the calculated SDH is the acceptance criteria used in TS Surveillance requirement
- 4. 1. 1.
The TS surveillance requirement, refueling interlocks, and procedural controls assure that inadvertent criticality will not occur during core reload.
TS 3. 10.3, SDM demonstration, establishes additional controls after core reload so that
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no more than one control rod can be withdrawn.
In the event that inadvertent criticality occurs at this time, this additional control ensures that the RPS system would scram the reactor.
Therefore, SLC operability in OPCON 5
does not impact the ability to maintain SDH.
The SLC system is not designed to terminate an inadvertent criticality event during core alterations (OPCON 5)* with the vessel water level at least 22 feet above the top of the vessel flange.
The amount of sodium pentaborate solution in the SLC system is based on normal power operating vessel
- level, and with the reactor cavity flooded, the amount of sodium pentaborate solution may not be adequate to prevent recriticality.
Therefore, based on the above evaluation, the staff has determined that the SLC system is not required to be operable in OPCON 5
and that the associated action statement can be removed from the TS.
This proposed TS change is consistent with the Improved Standard Technical Specifications, NUREG-1434, issued September 28, 1992.
2.2 SLC System Tank Heaters Surveillance The purpose of the SLC system tank heaters is to maintain the temperature of the tank high enough to prevent the boric acid from precipitating out of
- solution, and to maintain the tank temperature while chemicals are being mixed.
During steady state operation, heater 'A's used to maintain tank temperature between 85'F and 95'F.
Typically both heaters are used during chemical mixing which is an endothermic reaction.
Currently the TS require that an 18-month operability test be performed on the heaters.
The test is performed by recording the initial tank temperature, energizing both heaters for 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />, and recording the temperature rise.
A 2 'F rise in tank temperature is required to demonstrate operability of the heaters.
The operability of heater 'A's also verified by other means, TS Surveillance Requirement
- 4. 1.5.a.
1 and a control room alarm.
Surveillance Requirement
- 4. 1.5.a.
1 is performed daily, and requires that the temperature of the sodium pentaborate solution be within the acceptance range for the solution concentration.
Failure of tank heater 'A'ould be detected by gradually decreasing tank temperature recorded during the surveillance.
In addition, the tank temperature is monitored by-a control room alarm.
In the event of, heater failure, it is not likely that a drastic reduction of tank temperature below the acceptance value of 70 'F would result, due to the average ambient temperature in the area of the tanks which is approximately 80 'F.
The operability of heater 'B', which is used during chemical addition and mixing, is verified by the procedure used when adding chemicals to the tank.
Prior to adding chemicals to the tank, the procedure instructs the operator to turn on heater 'B'nd verify that the tank temperature increases to above
100 'F from its normal temperature of 85 F to 95 'F, thereby verifying the operability of the 'B'eater.
The procedure also instructs the operator to.
ensure that the solution temperature does not decrease below 100 'F during the chemical addition.
The control room alarm provides further verification of heater operability, since heater operation is required to maintain tank temperature during chemical addition.
The 18-month surveillance requirement for SLC system tank heater operability is redundant to other surveillance requirements, procedures and controls which verify the operability of both the 'A'nd 'B'eaters.
Further the 18-month heater surveillance requirement does not ensure that the SLC tank solution temperature is maintained in the TS acceptance range.
This is verified by SLC solution temperature measurements.
Lastly, ambient temperatures in the SLC area are likely to maintain the SLC solution temperature in the acceptance range or prevent a rapid decrease in solution temperature.
The staff has reviewed the licensee submittal requesting a TS change involving the requirement for operability of the Standby Liquid Control (SLC) system in operational condition 5 with any control rod withdrawn and the surveillance
~
requirements for the SLC system tank heaters.
Based on the reasons discussed
- above, the staff finds this proposed TS change to be acceptable.
This proposed TS change is consistent with the Improved Standard Technical Specifications, NUREG-1434, issued September 28, 1992.
3.0 STATE CONSULTATION
In accordance with the Commission's regulations, 'the Pennsylvania State official was notified of the proposed issuance of the amendments.
The State official had no comments.
4.0 ENVIRONMENTAL CONSIDERATION
The amendments change a requirement with respect to installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20.
The NRC staff has determined that the amendments involve no significant increase in the amounts, and no significant change in the types, of any effluents that may be released offsite, and that there is no significant increase in individual or cumulative occupational radiation exposure.
The Commission has previously issued a proposed finding that the amendments involve no significant hazards consideration, and there has been no public comment on such finding (59 FR 42344).
Accordingly, the amendments meet eligibility criteria for categorical exclusion set forth'n 10 CFR 51.22(c)(9).
Pursuant to 10 CFR 51.22(b) no environmental impact statement or environmental assessment need be prepared in connection with the issuance of the amendments.
The Commission has concluded, based on the considerations discussed
- above, that:
(1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed
- manner, (2) such activities will be conducted in compliance with the Commission s regulations, and (3) the issuance of the amendments will not be inimical to the common defense and security or to the health and safety of the public.
Principal Contributor:
A. Cubbage pate:
December 20, 1994
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