ML20084R776
| ML20084R776 | |
| Person / Time | |
|---|---|
| Site: | Vogtle  |
| Issue date: | 05/31/1995 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20084R765 | List: |
| References | |
| NUDOCS 9506090409 | |
| Download: ML20084R776 (7) | |
Text
- _ _ _
. f esc o
g.~
4 UNITED STATES i
S NUCLEAR REGULATORY COMMISSION Ea
[
WASHINGTON, D.C. 20555-0001
\\
/
SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. 86 TO FACILITY OPERATING LICENSE NPF-68 AND AMENDMENT N0. 64 TO FACILITY OPERATING LICENSE NPF-81 GEORGIA POWER COMPANY. ET AL.
V0'TLE ELECTRIC GENERATING PLANT. UNITS 1 AND 2 G
DOCKET NOS. 50-424 AND 50-425 1.0 INTRODUCTIM By letter dated December 29, 1994, as supplemented by letter dated May 2, 1995, Georgia Power Company, et al. (GPC or the licensee) proposed license amendments to change the Technical Specifications (TS) for Vogtle Electric Generating Plant (Vogtle), Units 1 and 2.
The proposed changes would add requirements for the diesel generator (DG) load sequencer.
The amendment request was submitted to clarify the action to be taken if a load sequencer is temporarily out of service, and to avoid the possibility of an unnecessary plant shutdown in accordance with TS 3.0.3.
The May 2,1995, letter provided minor editorial changes that did not change the scope of the December 29, 1994, application and initial proposed no significant hazards consideration determination.
The amendment application requests a revision to the TS Table 3.3-2, paragraph 3.8.1.1, 3.8.1.2 limiting condition for operation (LCO), associated action staterrents, surveillance requirements for Modes 5 and 6, and the Bases section for TSs 3.3.1 and 3.8.1.1.
The amendment will add requirements for the load sequencer by identifying the appropriate action to be taken when a load sequencer is inoperable.
Each DG is designed as a source of backup electrical power to ensure availability of the plant's safety systems in case of a loss of offsite power (LOSP).
Because large power requirements are imposed on the DG, there is a need to load it sequentially. The load sequencer automatically starts its associated DG and sequentially loads the engineered safety feature (ESF) equipment to the 4160-V bus upon receipt of a safety injection (SI) signal after an accident or an LOSP.
The ESF equipment is arranged into several load groups.
Load groups are energized one at a time by the load sequencer to avoid instantaneous overloading of the DG.
When a load sequencer is inoperable, the solid-state protection system (SSPS) actuates DG support loads independent of the sequencer, which allows the DG to be started automatically on an SI signal from the SSPS.
The DG is also capable of starting and loading manually when the sequencer is not available.
The licensee confirmed that Emergency Operating Procedure 19100 includes steps for manually starting the DG, including the manual loading of the necessary DG support loads.
Currently, Vogtle TS 3.8.1.1, 3.8.1.2 (A.C. Power Sources, LCO), and their action statements do not specifically mention operability of the automatic 9506090409 950531 PDR ADOCK 05000424 P
-. load sequencer, even though it was included in the surveillance requirement (SR) in TS 4.8.1.1 and'4.8.1.2.
The instrumentation used to actuate the ESF equipment is identified in TS Table 3.3-2.
Although the load sequencer is not specifically listed in this table, its operability may be implied in the functional units 1.b., 6.d., and 8 of Table 3.3-2.
These changes to the TS should eliminate any confusion that may exist concerning the effects of an inoperable load sequencer on instrumentation listed in the functional units 1.b., 6.d., and 8 of Table 3.3-2.
The Vogtle TS contain actions to be taken in the event that both the preferred offsite and the onsite power sources for a train are unavailable. The proposed 12-hour action time for an inoperable sequencer was designated the same as that for an inoperable offsite power source or an onsite DG, Also, the proposed LC0 and the action statements are consistent with the provisions of the new standard TS for Westinghouse plants (NUREG-1431, Revision 0).
The NRC staff has reviewed the licensee's submittal and provides the following evaluation.
2.0 EVALUATION Chanae 1:
Section 3/4.3. Instrumentation GPC proposes the following changes to Table 3.3-2, functional unit 6.d.i and 11, for auxiliary feedwater loss of or degraded 4.16 kV ESF bus voltage:
change channels / train to channels / bus, change the applicable Action Statement number from 23 to 29, and add a footnote at the bottom of the page stating,
"** See functional unit 8."
Action 29 is also changed from--
a.
The inoperable channel is placed in the tripped condition within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />, and b.
The Minimum Channels OPERABLE requirement is met; however, an additional channel may be bypassed 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 of other channels per Specification 4.3.2.1.
to--
a.
With a number of OPERABLE channels one less than the Total Number of Channels, STARTUP and/or POWER OPERATION may proceed provided the inoperable channel is placed in the tripped condition within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />, an additional channel may be bypassed 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 of other channels per Specification 4.3.2.1.
b.
With two or more channels inoperable for one bus, satisfy the minimum channels OPERABLE requirement by restoring one or more channels to OPERABLE status within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> or be in at least H0T STANDBY within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in COLD SHUTDOWN within the following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />.
~.
L j
~
? GPC also expands the Bases for TS Section 3/4.3, Instrumentation, to discuss the supplemental function the automatic load sequencer provides to the engineered safety feature actuation system (ESFAS) versus its more I
substantial role in defining the operability of electrical power sources.
The following paragraphs are added to the Bases in Page B 3/4 3-1:
t The engineered safety features actuation system does not include an explicit functional unit for the automatic load j
i sequencer. An inoperable load sequencer would affect the ability.to detect and respond to a loss of power or i
undervoltage and thus is included with the instrumentation that must be available to meet the requirements of functional. units 6.d.i. and 11., as well as 8.a. and b.
Since the hardware is the same for each of these functional units, a common action j
statement is used. The mode of applicability for functional unit 6.d. does not include Mode 4 since the AFW is not required to be operable in Mode 4; therefore, a footnote has been added i
that refers to functional unit 8.a. and b. which requires the j
instrumentation to be operable in Mode 4.
j An inoperable automatic load sequencer does not impact the j
operability of the automatic actuation logic and actuation relays (functional unit 1.b). The hardware referred to by this functional unit is not contained within the automatic load i
sequencer, but in the solid-state protection system. The i
effects of an inoperable automatic load sequencer is that the associaied onsite or offsite 4.16 kV emergency power sources may not correctly respond to an ESF or loss of power signal.
The appropriate action for an inoperable automatic load sequencer is closely related to the action for an inoperable i
diesel generator and an associated offsite source with an energized 4.16 kV bus. The appropriate actions for an inoperable automatic load sequencer are included in specification 3.8.1.1 and are discussed in the basis for Technical Specification 3/4.8.1. Action statement 29 for inoperable undervoltage channels is commensurate with that for i
an inoperable automatic load sequencer, and its basis is enveloped by the justification given for Technical i
Specification 3/4.8.1.
The instrumentation used to actuate the ESF for the SI signal is identified in Table 3.3-2 of the TS. The automatic load sequencer is not specifically listed in this table, although its operability may be implied. Currently, if the automatic load sequencer is inoperable, it is necessary to evaluate the appropriate actions based on Table 3.3-2 for inoperable ESFAS instrumentation. Functional units 6.d.i. and 11. and i
functional units 8.a. and b. refer to instrumentation that senses loss of or degraded voltage on the 4.16 kV buses.
The same instrumentation is used for both functional units.
It senses loss of or degraded voltage and sends a signal to the automatic load sequencer. Therefore, the appropriate action to be taken when this instrumentation, or a portion of it,.is inoperable should be the same for 6.d.i. and 11. and 8.a. and b.
J
. The proposed changes in TS 3/4.3 - Instrumentation are consistent with this discussion and, therefore, are acceptable to the staff.
Chance 2:
Section 3/4.8. Eldctrical Power Systems. Ooeratino LCO Section 3.8.1.1, paragraph a:
In this section, GPC proposes to add the following words: "each with an automatic load sequencer."
~
LC0 Section 3.8.1.1, paragraph b:
In this section, GPC proposes to add a new Subsection 4 which says "An automatic load sequencer."
Action Statements a, b and c: GPC proposes to add the following words "due to other than an inoperable automatic load sequencer." Also, the following paragraph "g" is added, which states: "With less than the above minimum required A.C. electrical power sources OPERABLE due to an inoperable automatic load sequencer, restore the inoperable automatic load sequencer to OPERABLE status within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> or be in at least HOT STANDBY within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in COLD SHUTDOWN within the following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />."
These changes associate the determination of an operable electrical power source (either offsite power or a DG) with that of an operable automatic load sequencer. These changes also distinguish the different actions required when an electrical power source has been declared inoperable due to an inoperable automatic load sequencer versus the actions required for inoperability due to some other reason.
The proposed LC0 of 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> for an inoperable load sequencer during Modes 1-4 is in agreement with, and the action statements folicw the intent of NUREG-1431 (Revision 0), and are acceptable to the staff.
Chance 3:
Section 3/4.8. Electrical Power Systems. Shutdown LCO Section 3.8.1.2, paragraph a:
In this section, GPC proposes to add the following words, " including the loss of power and undervoltage function of the associated automatic load sequencer."
LC0 Section 3.8.1.2, paragraph b:
In this section, GPC proposes to add the following subparagraph 4 stating, "The loss of power and undervoltage function of the associated automatic load sequencer."
In this section, GPC proposes to change the section number from 4.8.1.2 to 4.8.1.2.1 and to delete the reference of specification "4.8.1.1.2a.5" but added the reference to specifications "4.8.1.1.2h, i, and J."
In this section, GPC proposes to add a new Section 4.8.1.2.2, stating, "At least once per 18 months during shutdown, verify the loss of power and undervoltage function of the associated
[
. automatic load sequencer OPERABILITY upon LOSP signal by verifying deenergization of the emergency bus, load shedding of the operating loads from the emergency bus, and verifying the diesel starts and energizes the emergency bus with the available auto-connected shutdown loads."
GPC also expands the Bases for TS Section 3/4.8, Electrical Power Sources, by adding the following paragraph to the Bases on Page B 3/4 8-1.
The ACTION times specified for an inoperable automatic load sequencer are based on the times allowed when a combination of one diesel generator and one offsite circuit is inoperable.
Under this condition the 4.16 kV Class IE bus would remain energized. The ACTION conservatively addresses any consequential effects of an inoperable load sequencer on other engineered safety features.
In Modes 5 and 6 the automatic load sequencer is necessary to automatically strip the loads from the 1E bus and start the operable diesel generator in the event of a loss of offsite power (LOSP). Since the design basis LOCA is not applicable in Modes 5 and 6 the automatic LOCA load sequencer function of the load sequencer is not required to be demonstrated as operable.
Therefore, those surveillances that require sequencing of loads because of an SI signal are not required in Modes 5 and 6.
Thelossofdowerandundervoltagefunctionsaretheaspectsof seauencer operation that:
- 1) function to trip all closed breakers or. the 4.16 kV Class IE bus on a loss of or degraded voltage;
- 2) start the associated diesel generator; 3) close the breaker to supply power to the 4.16 kV Class IE bus from the associated diesel generator; and, 4) close the breakers to supply power from the 4.16 kV Class IE bus to the LOSP required loads in the appropriate sequence.
During shutdown, the operability of the loss of power and undervoltage function for Modes 5 and 6 of the automatic load sequencer is not affected by the inability to sequence and load equipment that is not required to be operable in Modes 5 and 6.
Surveillances to show operability of the loss of power and undervoltage: function of the automatic load sequencer will only include that. equipment that is required to be OPERABLE in Modes 5 and 6.
These changes state that the only function of the automatic load sequencer required during shutdown modes of operation is the loss of power and undervoltage protection associated with the applicable bus and the electrical power source. The electtical power source SRs applicable during shutdown modes of operation have also been revised to exclude those SRs that are not required and are therefore exempted from applicability. The Bases of Section 3/4.8, Electrical Power Sources, are being revised to explain the basis of the LC0 for an inoperable automatic load sequencer. A description is also being added to the Bases for the
. only function the automatic load sequencer is required to perform during shutdown Modes 5 and 6 and to address why certain surveillances are not required to be applicable during that same timeframe.
The staff finds these proposed changes, as clarified in discussion with the licensee, to be acceptable on the basis that they are consistent with the staff's interpretation of the Vogtle TS and the TS shutdown requirements.
In summary, the purposes of the previously discussed changes to the Vogtle TS are to identify the appropriate actions to be taken when an automatic load sequencer is inoperable, to clearly identify which functions of the automatic load sequencer are required to be operable during different modes of plant operation, and to avoid the unnecessary application of TS 3.0.3.
The proposed changes should eliminate any confusion that may exist concerning the effects of an inoperable load sequencer. The staff has concluded that the proposed TS changes are consistent with the provisions of NOREG-1431 (Revision 0).
The proposed changes in the TS will not change the design, function, or method of operation of any equipment at Vogtle and will not create the possibility of a new or different kind of accident from any accident previously evaluated.
Therefore, the proposed TS changes are acceptable.
3.0 STATE CONSULTATION
In accordance with the Commission's regulations, the Georgia State official was notified of the proposed issuance of the amendments.
The State official had no comments.
4.0 ENVIRONMENTAL CONSIDERATION
The amendments change requirements with respect to installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20 and change surveillance requirements.
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 (60 FR 6301 dated February 1,,1995). Accordingly, the amendments meet the eligibility criteria for categorical exclusion set forth in 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.
4
e
5.0 CONCLUSION
The Comission has concluded, based on the considerations discussed that:
public w(1) there is reasonable assurance that the health and safety of the ill not be endangered by operation in the proposed manner activities will be conducted in compliance with the Comission's r,eg(2) and (3 defense) and security or to the health and safety of the the issuance of the amendments will not be inimical to the comonulatio Principal Contributor:
S. K. Mitra Date: May 31, 1995 I
l
-