ML20070J446
| ML20070J446 | |
| Person / Time | |
|---|---|
| Site: | North Anna  |
| Issue date: | 07/18/1994 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20070J444 | List: |
| References | |
| NUDOCS 9407250116 | |
| Download: ML20070J446 (7) | |
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UNITED 'iTATES l'
NUCLEAR REGULATORY COMMISSION
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WASHINGTON, D.C. 20555 4 001 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REALT0R REGULATION i
1M AND 165 T0 RELATED TO AMENDMENT NOS.
FACILITY OPERATING LICENSE NOS. NPF-4 AND NPF-7 i
VIRGINIA ELECTRIC AND POWER COMPANY OLD DOMINION ELECTRIC COOPERATIVE NORTH ANNA POWER STATION. UNITS N0. I AND NO. 2 DOCKET NOS. 50-338 AND 50-339
1.0 INTRODUCTION
By letter dated March 1,1994, as supplemented by letter dated June 16, 1994, the Virginia Electric and Power Company (the licensee) proposed changes to the Technical Specifications (TS) for the North Anna Power Station, Units No. I and No. 2 (NA-l&2).
The proposed changes would eliminate certain surveillance requirements for the emergency diesel generators (EDGs) which have been determined to be unnecessary.
These changes are in accordance with the NRC Technical Specification Improvement Program as documented in Generic Letter j
(GL) 93-05, "Line-Item Technical Specifications Improvements For Testing i
During Power Operation dated September 27, 1993, and NUREG-1366, " Improvements To Technical Specifications Surveillance Requirements," dated December 1992.
The June 16, 1994 letter provided additional information requested by the staff.
This additional information did not alter the proposed action or 4
affect the staff's determination of no significant hazards consideration as noticed in the Federal Reaister on March 30, 1994 (59 FR 14899).
The NRC has completed a comprehensive examination of surveillance requirements in technical specifications that require testing at power. The evaluation is documented in NUREG-1366.
The NRC staff found, that while the majority of testing at power is important, safety can be improved, equipment degradation decreased, and an unnecessary burden on personnel resources eliminated by reducing the amount of testing at power that is required by TS.
Based on the results of the evaluations documented in NUREG-1366, the NRC issued GL 93-05.
The safety function of the EDGs is to supply AC electrical power to plant safety systems whenever the preferred AC power supply is unavailable.
Consistent with GL 93-05, Item 10.1 and NUREG-1366, the licensee is requesting a change to the testing requirements of an operable EDG when the other EDG is inoperable or an offsite circuit is inoperable, the separation of the hot restart test of an EDG from the 24-hour loaded run, and the elimination of fast loading of EDGs except for the 18-month surveillance test of the Loss af Offsite Power (LOOP) capability.
9407230116 940718 PDR ADOCK 05000338 P
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2.0 DLSLU.51LQti NA-1&2 is a dual unit site with four emergency diesel generators.
Two emergency diesel generators are dedicated for each unit.
TS 3/4.8.1.1 requires that while in Modes 1 through 4, as a minimum, each unit will have two physically independent circuits between the offsite transmission network and the onsite Class IE distribution system, and two separate and independent j
diesel generators.
The current NA-1&2 TS 3/4.8.1.1.a requires that operable EDGs be started and loaded to demonstrate their operability in the event an offsite AC source (s) becomes inoperable. The intent of this testing is to provide added assurance that the oper;ble EDGs are capable of supplying emergency power when the offsite AC sources are degraded (e.g., power fluctuations in the grid, loss of one or both offsite AC sources). The most probable cause of an offsite AC source becoming degraded is severe weather or an off-normal grid condition.
Fer1back from severe weather or other off-normal grid conditions can also cause the loss of an EDG (if the EDG is tied to the offsite source when it becomes inoperable) leaving the EDG's safety bus without an AC power source.
NRC Information Notice 84-69 warns that disturbances on the offsite source can adversely affect EDG reliability when an EDG is operated connected to offsite sources. Therefore, EDG availability is potentially lessened by requiring a demonstration of operability which connects the EDG to the same grid being supplied by offsite AC power. The deletion of the TS requirement to start and load operable EDGs when an offsite AC source becomes inoperable does not increase the probability that the operable EDGs will be unable to perform their safety function.
Therefore, in accordance with NRC GL 93-05, the licensee is requesting that NA-1&2 TS be amended to delete the requirement to conduct operability testing of the EDGs when one or both offsite AC sources become inoperable.
Operability testing of an EDG is also required by NA-1&2 TS 3/4.8.1.1.b whenever the alternate safety buses' EDG is declared inoperable due to any cause other than preplanned preventative maintenance or testing.
Since there are many potential failures of EDG subsystems that would not be classified as a common mode failure yet would cause an EDG to be declared inoperable, this TS requirement can cause unnecessary testing of the operable EDG when the alternate safety buses' EDG is declared inoperable due to inoperable support equipment or an independently testable component. NUREG-1366 stated that "The NRC staff recommends that the requirements to test the remaining diesel generator (s) when one diesel generator is inoperable due to any cause other than preplanned preventative maintenance or testing be limited to those situations where the cause for inoperability has not been conclusively demonstrated to preclude the potential for a common mode failure. However, when such testing is required, it should be performed within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> of having determined that the diesel generator is inoperable." However, NUREG-1431 allows 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> to determine the cause of the inoperable EDG's failure before requiring testing of the remaining operable EDG.
This matter was discussed with the NRC staff on May 17, 1994, and the staff stated that 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> was an appropriate time frame for testing the remaining operable EDG. Therefore, the licensee is requesting that NA-l&2 TS be amended to require operability testing of an EDG only when the alternate safety buses' EDG is declared
(J-7 inoperable for any cause other than an inoperable support system, an independently testable component, or preplanned preventative maintenance or testing.
This testing shall be completed within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, unless the absence of any potential common mode failure for the remaining diesel generator is conclusively demonstrated.
NA-l&2 TS 3/4.8.1.1.2.c currently requires that during the EDG fast start surveillance test conducted at least once per 184 days, the EDG be loaded to an indicated 2500 to 2600 kW in less than or equal to 60 seconds.
As stated in NUREG-1366, this fast loading is the most significant cause of accelerated degradation of diesel generators.
In accordance with NRC GL 93-05, the licensee is requesting that the NA-l&2 TS be amended to delete the fast loading requirements and allow gradual loading in accordance with the manufacturer's recommendations for all surveillance requirements with the exception of the once per refueling outage LOCP surveillance test which will still require full loading in less than or equal to 60 seconds.
NA-l&2 TS 3/4.8.1.1.2.d.ll.a surveillance requirement is being added to verify the EDG's hot restart capability by operating the diesel generator loaded to an indicated 2500 to 2600 kW for 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> or until operating temperatures have stabilized.
It is the staff's understanding that stabilization refers to the EDG's full mass of metal reaching its thermal equilibrium.
NA-l&2 TS 3/4.8.1.1.2.7 currently requires that within 5 minutes of shutting down the EDG following the refueling outage 24-hour loaded test run that the LOOP surveillance test be conducted. The sequencing of the LOOP test following the 24-hour loaded test run can have a significant impact on the outage schedule. Unnecessary outage delays could result from the inability to conduct the LOOP test within the 5-minute time constraint following the 24-hour run. Additionally NUREG-1366 stated that "There is no safety reason for performing a startup of a diesel within 5 minutes of the 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> test run as is required by Technical Specifications." As described in NUREG-1366, on February 15, 1988, Duke Power Company proposed to separate the 24-hour test run from the 5-minute hot restart test.
The reason for requesting this change was that separating these two required tests gave the plant operators added flexibility and prevented critical path complications during the outages.
This change was approved by the NRC on July 28, 1988.
The licensee is requesting the same change for NA-l&2 by eliminating the requirement for the LOOP test following the 24-hour loaded run and adding a new surveillance requirement of a simple hot restart test following a 2-hour loaded run of the EDG.
Additional minor administrative changes are included in this amendment request to correct typographical errors and improve readability.
3.0 SPECIFIC CHANGES These TS changes apply to both NA-l&2 (unless otherwise noted).
TS 3.8.1.1 Actions are being changed as follows:
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Action "a" : Delete sentence "If either EDG has not been successfully tested within the past 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, demonstrate its OPERABILITY by performing Surveillance Requirement 4.8.1.1.2.a.4 separately for each such EDG within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />."
Action "b": End the first sentence at "thereafter" by deleting the semi-colon
(;) and adding a period (.).
Delete the remainder of Action "b" and replace with "If the EDG became inoperable due to any cause other than an inoperable support system, an independently testable component, or preplanned preventative maintenance or testing, demonstrate the OPERABILITY of the remaining OPERABLE EDG by performing Surveillance Requirement 4.8.1.1.2.a.4 within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />", unless the absence of any potential common mode failure for the remaining diesel generator is demonstrated.
Restore the diesel generator to OPERABLE status within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> or be 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 />."
At the bottom of page 3/4 8-1 replace the single asterisk (*) item with "*This action is required to be completed regardless of when the inoperable EDG is restored to OPERABILITY."
l Action "c" : In the first sentence after "...and if the EDG became inoperable due to any cause other than" and "an inoperable support system, an independently testable component, or."
In the first sentence after "...within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> ** delete semicolon (;) and insert ", unlens the absence of any potential common mode failure for the remaining diesel generator is demonst rated," and end the sentence.
Start a new sentence at " Restore one of the inoperable...". Delete the last sentence of Action "c" since a diesel test may not be required.
Action "d" : In the first sentence delete the phrase "; demonstrate the OPERABILITY of two diesel generators by sequentially performing Surveillance Requirement 4.8.1.1.2.a.4 on both diesels within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> unless the diesel generators are already operating;."
In the first sentence after "H0T STANDBY" delete the misspelled word "wtihin" and replace with "within" (misspelled on i
NA-1 only).
In the second sentence after "Following restoration of one offsite" delete the misspelled word "cource" and replace with " source" (misspelled on NA-1 only). Delete the last sentence of Action "d" as diesel testing is not required.
Action "e" : The last sentence of this action is deleted since it is unnecessary clarification.
At the bottom of page 3/4 8-2 replace the single asterisk (*) item with "*This action is required to be completed regardless of when the inoperable EDG is restored to OPERABILITY."
SR 4.8.1.1.2.c: Change the third sentence to read "the generator shall be manually synchronized to its appropriate emergency bus, gradually loaded **to an indicated 2500 to 2600 kw***, and operated for at least 60 minutes."
SR 4.8.1.1.2.d.7: Delete the last sentence
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SR 4.8.1.1.2.d.9.a (Unit 1 only): Replace the period (.) with a comma (,).
SR 4.8.1.1.2.d.10 (Unit 1 only): Delete the second "a)" and insert "b."
l SR 4.8.1.1.2.d: Add surveillance requirement after SR 4.8.1.1.2.d.10:
"11. Verifying the diesel generator's hot restart capability by:
a)
Operating the diesel generator ** loaded to an indicated 2500 to 2600kW*** for 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> or until operating temperatures have stabilized, and b)
Within 5 minutes of shutdown verify the diesel generator can be started *** and accelerated to at least 900 rpm in less than or equal to 10 seconds. The generator voltage and frequency shall be 4160 420 volts and 60 1.2 Hz within 10 seconds after the start signal."
Page 3/4 8-6 (Unit 2 only) : Add notation **** This test band is i
meant for guidance to avoid routine overloading of the engine.
Loads in excess of this band for special testing under direct monitoring of the manufacturer or momentary variations due to changing bus loads shall not invalidate the test."
4.0 EVALVATIM The proposed changes will modify the requirement for operability testing of an EDG when the alternate safety buses' EDG is inoperable, delete the requirement for operability testing of the EDGs when one or both offsite AC sources are inoperable, eliminate fast loading of EDGs except for the LOOP test, and separate the hot restart test from the 24-hour loaded test run of the EDGs.
This reduction in operability testing and modified surveillance requirements of the EDGs at power has been examined and accepted by the NRC staff in GL 93-05, Item 10.1.
The staff found that while the majority of the testing at power is important, safety can be improved, equipment degradation decreased, and an' unnecessary burden on personnel resources eliminated by reducing the amount of testing at power that is required by TS. Therefore, based on all of the above, the staff finds-the proposed changes to be acceptable.
5.0 STATE CONSULTATION
In accordance with the Commission's regulations, the Virginia State official was notified of the proposed issuance of the amendment. The State official had no comment.
6.0 ENVIRONMENTAL CONSIDERATION
bise amendments change a requirement with respect to installation or use of a f cility component located within the restricted area as defined in 10 CFR Part 20 and changes surveillance requirements. The NRC staff has determined
6 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 these amendments involve no significant hazards consideration and there has been no public comment on such finding (59 FR 14899). Accordingly, these 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.
7.0 CONCLUSION
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:
Leon B. Engle Date: July 18,1994 f
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