ML20080G985
| ML20080G985 | |
| Person / Time | |
|---|---|
| Site: | South Texas  |
| Issue date: | 02/02/1995 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20080G983 | List: |
| References | |
| GL-93-05, GL-93-5, NUDOCS 9502140290 | |
| Download: ML20080G985 (8) | |
Text
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4 UNITED STATES i
I E
NUCLEAR REGULATORY COMMISSION
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f WASHINGTON, D.C. 20565-0001
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NOS. 68 AND 57 TO FACILITY OPERATING LICENSE NOS. NPF-76 AND NPF-80 HOUSTON LIGHTING & POWER COMPANY CITY PUBLIC SERVICE BOARD OF SAN ANTONIO CENTRAL POWER AND LIGHT COMPANY CITY OF AUSTIN, TEXAS DOCKET NOS. 50-498 AND 50-499 SOUTH TEXAS PROJECT. UNITS 1 AND 2
1.0 INTRODUCTION
By application dated June 6, 1994, as supplemented by letters dated November 17, 1994, and December 5, 1994, Houston Lighting & Power Company, et.al., (the licensee) requested thanges to the Technical Specifications (Appendix A to Facility Oper: ting *'. m se Nos. NPF-76 and NPF-80) for the South Texas Project, Units ?.nd 2 (STP). The proposed changes would revise Technical Specification 3.8.1.1 to eliminate unnecessary testing of the r
standby diesel generators (SDG). The amendments would also make changes to surveillance requirement 4.8.1.1.2 to reduce mechanical stress on the diesel engines. The November 17, 1994, and "ST-HL-AE-4947, Requests That Term Ambient, in Surveillance Requirement 4.8.1.1.2.a.2 Be Changed to Standby, Re Proposed Amend to Licenses NPF-76 & NPF-80 for South Tx Project by Revising [[TS" contains a listed "[" character as part of the property label and has therefore been classified as invalid., Electrical Power Sys-ac Sources-Operating|December 5, 1994, letter]]s provided clarifying information and did not change the initial no significant hazards consideration determination.
2.0 EVALUATION In September 1993, the NRC issued Generic Letter 93-05, "Line Item Technical Specifications Improvements to Reduce Surveillance Requirements for Testing During Power Operations." The NRC found that safety could be improved, equipment degradation decreased, and unnecessary burdens on personnel resources eliminated by reducing the amount of testing required by technical specifications (TS). Several of the recommendations involved eliminating certain tests for SDGs. The licensee incorporated those changes that were compatible with plant operating experience. The licensee also proposed changes based on the guidance in NUREG-1366, " Improvements to Technical Specification Surveillance Requirements," NUREG-1431, " Standard Technical Specifications - Westinghouse Plants," Gen:rie Letter 84-15, " Proposed Staff Actions to Improve and Maintain Diesel Generato.- Reliability", and industry and plant operating experience. The r,roposed changes are evaluated below.
A 05000493 PDR
. Technical Soecification 3.8.1.1 Actions a. and e.
TS 3.8.1.1 Actions a. and e. require all operable SDGs be started as a demonstration of operability whenever one or more of the offsite AC power t
sources is declared inoperable.
The proposed amendment would eliminate this requirement to demonstrate SDG operability.
This change does not affect the ability of the SDGs to perform their design function since the inoperability of an offsite AC power source has no affect on the reliability of a SDG. This change is consistent with the recommendations given in GL 93-05 and therefore is acceptable.
Technical Specification 3.8.1.1 Actions b. and c.
TS 3.8.1.1 Actions b. and c. require all remaining operable SDGs be started as a demonstration of operability whenever one SDG is declared inoperable except when the SDG is inoperable due to preplanned preventive maintenance or testing.
The proposed amendment would revise the testing exclusion to include an inoperable support sy: tem and an independently testable component. The addition of these testing exclusions will prevent the need to test the remaining SDGs when the source of the inoperability originated in a support system or in an independently testable component. The proposed amendment would also eliminate the testing requirement of the remaining operable SDGs i
when a SDG is declared inoperable if it can be demonstrated that there is no common mode failure for the remaining SDGs.
In addition, this amendment replaces the requirement to test the SDG within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> with a requirement to test within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> for Action b.
These changes conform with the guidance in GL 93-05 and are acceptable.
Surveillance Reouirement 4.8.1.1.2 A note is added to this surveillance requirement that states that all diesel starts for the purpose of these surveillances may be preceded by a prelube l
period. This reduces wear on the engines and is in accordance with GL 84-15.
This change is acceptable.
Surveillance Reouirement 4.8.1.1.2.a.2 The proposed amendment revises a footnote to SR 4.8.1.1.2.a.2 and moves it to a new consolidated list of notes. The new footnote states that all diesel starts for the purpose of this surveillance may be modified starts involving reduced fuel (load limit) and/or idling and gradual acceleration to synchronous speed. This note is intended to reduce the number of " fast I
starts" that the SDGs will experience during performance of SRs by allowing modified starting. A " fast start" occurs when the SDG is started with maximum fuel and is accelerated to synchronous speed as rapidly as possible.
Fast starting is considered to be detrimental to the SDGs for the following reasons.
First, when a diesel engine is started on maximum fuel, the peak cylinder firing pressures can be several times higher than the equivalent firing pressures at continuous rated output. This can cause rapid degradation of bearings, piston pins, compression rings, and cylinder walls.
- Second,
. rapid acceleration from standby conditions to synchrcnous speed can cause internal engine components to expand at a more rapid rate than the cylinder liners / engine block. This results in reduced clearances for a period of time which can, in turn, cause accel? rated piston ring and cylinder liner wear.
The effect of this note will be to reduce the required number of fast starts to one every 184 days for this SR.
The purpose of reqairing SDG fast start capability is to ensure the SDG will reach rated speed and voltage in a time frame that will support the accident analysis. However, this capability can be adequately demonstrated without requiring an actual fast start for every SDG surveillance. The speed of a SDG start is dependant on (1) the amount of fuel injected, (2) the starting air By ensuring pressure, and (3) the mechanical condition of the diesel engine.
that the fuel setting and starting air pressure are the same for each modified start attempt, and by monitoring the time it takes for the SDG to reach a predetermined speed, information can be obtained regarding the overall diesel engine mechanical condition. Any significant change in time is an indication of some change in mechanical condition that requires investigation. This type of monitoring, in conjunction with a periodic actual fast start, will provide adequate assurance of SDG fast start capability while minimizing the detrimental effects of fast starting.
Based on the above, the staff concludes that note (3) as applied to SR 4.8.1.1.2.a.2 is acceptable because the modified starts will serve to improve Implicit in this staff acceptance is the condition that the SDG reliability.
licensee will develop and implement procedures to monitor all SDG starting times and to ensure that the SDG governor settings are returned to the appropriate positions following any modified start.
The The proposed amendment also changes the word " ambient" to " standby".
change was made to reflect the wording in NUREG-1431.
This wording is consistent with the wording in the bases and will climinate any confusion.
The staff has found the word " standby" to be more descriptive of the actual conditions of the diesel and this change is acceptable.
Surveillance Reauirement 4.8.1.1.2.a.3 SR 4.8.1.1.2.a.3 rer,uires the start and loading of the SDG to greater than or i
equal to 5500 kW in less than or equal to 10 minutes. The proposed amendment will replace the specific load with a band of 5000 kW to 5500 kW. The load band is provided to avoid routine overloading of the diesel generators caused by the need to ensure the load is never less than the maximum expected i
accident loads.
Industry experience has shown that a aiesel generator operating at 90 percent of continuous design ratino with temperature, pressures, etc. within their normal ranges, will also operate satisfactorily at 100 percent of continuous design rating. Therefore, a load band, ns opposed to a load minimum is acceptable.
The proposed amendment also adds a note stating that momentary transients outside this load band will not invalidate the test.
Because momentary
. transients outside the load range may be caused by changing bus loads and are not indicative that a diesel is not functioning properly, this state.r.ent will avoid additional tests being performed unnecessarily.
The proposed amendment will also remove the time limit of 10 minutes and substitute a note which allows the generator to be loaded in accordance with manufacturer's recommendations. This allows a slower loading rate which will eliminate unnecessary mechanical stress and wear on the diesel and will ultimately improve diesel reliability. This is in accordance with GL 93-05 and NUREG-1366 which recommend that all testing of diesel generators, with the exception of the loss-of-offsite power (LOOP), safety injection (SI) and LOOP /SI tests (which are to be canducted at least once per 18 months), be performed by gradual loading in accordance with vendor recommendations.
The proposed amendment will also delete a footnote to Surveillance Requirement 4.8.1.1.2.a.3.
This footnote clarified the conditions that should precede the SDG start.
These conditions and warmup procedures are those recommended by the diesel manufacturer and therefore the footnote can be replaced by the note that the loading be performed in accordance with vendor's recommendation.
These changes conft m with the recommendations of GL 93-05 and are acceptable.
Surveillance Reauirements 4.8.1.1.2.c and d Surveillance requirements 4.8.1.1.2.c and d., which require sampling of new fuel oil, are relocated to an administratively controlled fuel oil monitoring.
program.
A new paragraph is added to Administrative Controls Section 6.8.3 which describes the fuel oil monitoring program. The proposed surveillance requirements are similar to SR 3.8.3.3 of NUREG-1431, " Standard Technical Specifications for Westinghouse Plants."
However, NUREG-1431 contains Limiting Conditions for Operation (LCO) which state that if the stored fuel oil total particulates are not within limit or if the new fuel oil properties are not within limit, the diesel must be declared inoperable. The proposed surveillance requirement does not have an LC0 associated with it. By letter dated November 17, 1994, the licensee committed to incorporate the LCO, consistent with NUREG-1431, when it converts to the improved standard technical specification format.
Until then, the licensee has committed to declare a diesel generator inoperable if the associated fuel oil fails to meet r
the acceptance criteria identified in the diesel fuel oil program.
The staff considers this to be an acceptable interim action.
The proposed new paragraph in the Administrative Controls Section 6.8.3(i) states that "the program shall include sampling and testing requirements, and acceptance criteria, all based on applicable ASTM Standards."
In its letter dated November 17, 1994, the licensee described its exceptions to the ASTM standards associated with the testing of diesel fuel oil.
These include:
(1) The sample containers used for sampling fuel oil will be prepared using ASTM D-2276 method with the exception of capping the bottle with plastic film rinsed with filtered petroleum ether.
(2) The viscometer bath temperature will be allowed a 0.05 degree C variation during the performance of Viscosity Kinematic Method, ASTM 0445.
(3) The temperature of the water bath used during the performance of Determination of Water and Sediment in Oil, will be maintained at 12012*F, but is not required to be recorded.
l (4) An alternate thermometer that meets the accuracy requirements of ASTM D93 will be used during the Determination of Flash Point in 011.
(5) The Determination of Flash Point in 011 testing analysis results will not be corrected for barometric pressure unless the Flash Point falls below 130*F.
(6) During the performance of ASTM D2276, Determination of Particulate i
Contamination in Fuel 011, the sample bottle will be wiped clean in the region of the cap, and a clean watch glass will be used to cover the i
funnel opening of the assembled apparatus.
(7) The results of the performance of ASTM D2276, Determination of Particulate Contamination in Fuel 011, will be recorded to two significant digits.
The staff finds these exceptions acceptable.
The sampling and testing requirements, and acceptability criteria of the program are consistent with the current surveillance requirements.
Based on the licensee's commitment to declare a SDG inoperable when its associated fuel oil is not within specifications, and the acceptability of the licensee's exemptions to the ASTM standards for the testing of diesel fuel oil, this r
change is acceptable.
Surveillance Reouirements 4.8.1.1.2.e.2. e.3. e.7 and e.10 A note is added to each of these surveillance requirements which states that the diesel generator start for these surveillances may be a modified start.
r As discussed above (see SR 4.8.1.1.2.a.2), monitoring of modified starts, in conjunction with a periodic actual fast start, will provide adequate assurance of SDG fast start capability while minimizing the detrimental effects of fast starting. The effect of this note will be to reduce the required number of fast starts required at each refueling to no more than three. Based on the above, the staff concludes that note (3) as applied to SR 4.8.1.1.2.e.2, e.2, e.7 and e.10 is acceptable because the modified starts will serve to improve SDG reliability.
An additional note is added to Surveillance Requirements 4.8.1.1.2.e.2, e.3, and e.7 which states that the generator loading for these surveillances may be accomplished in accordance with vendor recommendations. This change permits
1 1
_5-I
.t 1
gradual loading so that mechanical stress and wear on the die!
minimized.
change is consistent with GL 93-05 and is acceptable.
}
Surveillance Reauirement 4.8.1.1.2.e.7 surveillance Requirement 4.8.1'.l.2.e.7 verifies that the diesel generatl operates for at least 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.the test, the diesel generator be loaded to grea and during the remaining 22 hours2.546296e-4 days <br />0.00611 hours <br />3.637566e-5 weeks <br />8.371e-6 months <br />, the diesel generator be loaded to greater The proposed amendment would replace the minimum
. than or equal to 5500 kW.
acceptable loading with a load range of 5700 kW to 6050 kW for the first 2The pj hours and 5000 kW to 5500 kW for the remaining 22 hours2.546296e-4 days <br />0.00611 hours <br />3.637566e-5 weeks <br />8.371e-6 months <br />.
i surveillance is to verify that the diesel generators can run for 22 hours2.546296e-4 days <br />0.00611 hours <br />3.637566e-5 weeks <br />8.371e-6 months <br /> at a i
load equivalent to 110 percent of the continuous duty rating and the remaining 22 hours2.546296e-4 days <br />0.00611 hours <br />3.637566e-5 weeks <br />8.371e-6 months <br /> at a load equivalent to 100 percent of the continuous duty rating per The continuous duty rating for these diesel l
Because generators is 5500 kW and 110 percent of this rating is 605 3
of a load will also operate at 100 percent load, running the diesel generators within the proposed load bands will ensure that the diesel gj The test band is provided to duty rating for the required amount of time.
6 This change is avoid routine overloading of the diesel generators.
j acceptable.
f The proposed amendment would also eliminate the requirement that the diesei generator reach the steady-state generator voltage and fr i
SDG will reach rated speed and voltage in a time frame that will support the l
seconds.
However, this capability car, be adequately demonstrated The speed j
accident analysis.
without requiring an actual fast start for every SDG surveillance.
of a SDG start is dependant on (1) the amount of fuel injected, (2) the l
starting air pressure, and (3) the mechanical condition of the diesel engine.
By ensuring that the fuel setting and starting air pr: =ure to reach a predetemined speed, information can be obtained regarding overall diesel engine mechanical condition.
an indication of some change in mechanical condition that requ fast start, will provide adequate assurance of SDG fast start capability while investigation.
The 10 second minimizing the detrimental effects of fast starting.
l requirement is based on the accident analysis which requires that the diesel generators achieve rated speed and voltage within 10 seconds to respond to
-large break loss-of-coolant accident when off-site power is not available.
l This surveillance is not a LOOP test and therefore, requiring that the diesel 1
9enerator perform a fast start results in unnecessary stress and wear.
l
-Therefore, for the purposes of this surveillance, gradual accelerated and l
loading of the diesel will not affect the test results and is acceptable.
l
O SR 4.8.1.1.2.e.7 also requires the start and loading of the SDG per 4.8.1.1.2.e.6 (simulated LOOP start and load test) within 5 minutes following the 24-hour run.
The proposed change will substitute starting the diesel in accordance with 4.8.1.1.2.a.2 (SDG start test) instead and eliminate the LOOP test. The purpose of starting the SDG within 5 minutes of the 24-hour run is to ensure that the heat which has accumulated during the 5 minutes following the 24-hour run has not resulted in significant expansion of the pistons that would affect the diesel's ability to start and operate successfully.
This change will prevent the unnecessary performance of a LOOP test when the only intent of the requirement was to verify the start of a hot engine.
Substituting the SDG start test will verify the diesel's ability to start and operate successfully, and eliminate the unnecessary mechanical stress and wear on the diesel engine caused by the rapid loading of the generator.
This change conforms with the recommendations of GL 93-05 and is acceptable.
SR 4.8.1.1.2.e.7 includes a footnote which states that if the SDG start test is not satisfactorily completed following the 24-hour run, it is not necessary to repeat the 24-hour run.
Instead, the SDG may be operated at 5500 kW for 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> or until operating temperature has stabilized.
The amendment would increase the run time to 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> in accordance with the guidance in GL 93-05.
The amendment would also replace 5500 kW with a load band of 5000-5500 kW.
Operation in this load band will ensure that the diesel generator achieves operating temperature and will avoid unnecessary overloading of the diesel.
These changes are acceptable.
lable 4.8-1 The proposed amendment contains an editorial change to move all footnotes from the bottom of the technical specification pages to a consolidated list below Table 4.8-1.
This is an editorial change and is acceptable.
Bases The licensee proposed several additions to the Bases section which provide a detailed discussion of the action statements and surveillance requirements for this technical specification. The staff noted an error in proposed Bases page B 3/4 8-2 on applicable safety analysis. Two trains of the onsite or one train of the offsite AC sources should be operable during accident conditions (the licensee had proposed one train of onsite or one train of offsite).
The licensee informed the staff that this error was an oversight and agreed with the revised wording.
The changes described above conform with GL 84-15, GL 93-05, NUREG-1431 and NUREG-1366 and are compatible with STP plant operating experience.
Therefore.
the proposed changes are acceptable.
i
3.0 STATE CONSULTATION
in accordance with the Commission's regulations, the Texas State official was notified of the proposed issuance of the amendment.
The State official haf a
comments.
4.0 ENVIRONMENTAL CONSIDERAILQH The amendment changes a requirement with respect to installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20 and changes surveillance requirements.
The NRC staff has determined that the amendment involves 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 amendment involv's no significant hazards consideration, and there has been no public comment on such finding (59 FR 37073). Accordingly, the amendment meets 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 amendment.
5.0 CONCLUSION
The Commission has concluded, based on the considerations discussed abova, 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 regulation:,
and (3) the issuance of the amendment will not be inimical to the common defense and security or to the health and safety of the public.
Principal Contributor:
Donna Skay Date:
February 2, 1995