ML20083M174
| ML20083M174 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 05/12/1995 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20083M167 | List: |
| References | |
| NUDOCS 9505190136 | |
| Download: ML20083M174 (6) | |
Text
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-i UNITED STATES j
NUCLEAR REGULATORY COMMISSION
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2 WASHINGTON, D.C. 20666-0001 o%...../
SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO.112 TO FACILITY OPERATING LICENSE NO. NPF-49
MILLSTONE NUCLEAR POWER STATION. UNIT NO. 3 DOCKET NO. 50-423
1.0 INTRODUCTION
By [[letter::B14971, Application for Amend to License NPF-49,incorporating Changes Recommended in GL 93-05 Re DG SR & Other DG SR Concerning Cold Starts|letter dated December 9,1994]], as supplemented by letter dated March 28, 1995, Northeast Nuclear Energy Company (NNEC0/the licensee) proposed changes to the Technical Specifications (TS) for Millstone, Unit 3.
The March 28, 1995, letter provided clarifying information that did not change the i
initial proposed no significant hazards. consideration determination. The proposed changes are the elimination of certain surveillance requirements (SRs) for the emergency diesel generators (EDGs) that have been determined to
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be unnecessary. These changes are in accordance with the NRC Technical Specification Improvement Program as documented in Generic Letter (GL) 93-05, "Line-Item Technical Specifications Improvements for Testing During Power Operation," September 27, 1993; NUREG-1366, " Improvements to Technical Specifications Surveillance Requirements," December 1992; and NUREG-1433,
" Improved Standard Technical Specifications," September 1992. This submittal supersedes the licensee's April 1,1993, request to change the placement of a footnote to the TS regarding the DG prelube system.
The U.S. Nuclear Regulatory Commission (NRC) staff has completed a comprehensive examination of SRs in the TS that require testing at power. The evaluation is documented in NUREG-1366. The NRC staff found that although most 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.
On the basis of the results of the evaluations documented in NUREG-1366, the NRC issued GL 93-05. NNEC0 proposes to modify Millstone, Unit 3 TS 3/4.8.1 and 4.8.1.1.2 by incorporating recommendations regarding EDG SRs included in GL 93-05 (Section 10-1) except two, which are discussed in the following section.
2.0 EVALUATION Millstone, Unit 3 TS 3/4.8.1.1.a requires that while in Modes 1 through 4, as a minimum, each unit have two physically independent circuits between the offsite transmission network and the onsite Class 1E distribution system, and 9505190136 950512 PDR ADOCK 05000423 P
d two separate and independent EDGs. The safety function of EDGs is to y
- ac electrical power to pir.t safety systems whenever the preferred ac,..ar supply is unavailable..
4 As mentioned in the previous section, NNECO is taking exception to two recommendations of GL 93-05. The first pertains to the loading and synchronization of the operable EDG during certain conditions, and the second pertains to the allowed timeframe to determine the operability of one EDG when l
the opposite train's EDG has been declared inoperable.
a i
GL 93-05 recommends that an operable EDG be started and loaded to demonstrate its operability in accordance with the vendor recommendations during the limiting condition for operation (LCO) when one offsite power source or one
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EDG is inoperable. To load the operable EDG, the EDG must be synchronized with the grid, which could subject the loaded EDG to grid faults and adversely affect its capability to perform its safety function. Severe weather or other off-normal grid conditions can cause the loss of an EDG, leaving the EDG's i
safety bus without an ac power source when the other EDG is inoperable.
In NRC Information Notice 84-69, " Operation of Emergency Diesel Generators,"
August 29, 1984, the staff warns that disturbances at the offsite source can 1
adversely affect EDG reliability when the EDG is connected to the offside e
source. Also, NUREG-1431, " Improved Standard Technical Specifications -
Westinghouse Plants," does not require that the EDG be loaded and connected to l
the offsite grid during the LCO. The staff agroes with NNECO that connecting and loading the operable EDG to the offside source is not necessary during the l
LCO.
In addition, Millstone, Unit 3 TS 3/4.8.1.1.b requires operability testing of
-1 an EDG within' 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> whenever the alternate ELG is declared inoperable for i
any cause other than preplanned preventive maintanance and testing. Since many potential failures of EDG subsystems would rot be classified as common mode failures yet would cause an EDG to be declared inoperable, this i_
TS requirement can cause unnecessary testing of operable EDGs when the j
alternate EDG is declared inoperable because of inoperable support equipment cr an independent testable component. NUREG-1366 states, I
The NRC staff recommends that the requirements to test the remaining diesel generator (s) when the one diesel generator is inoperable due to any cause other than preplanned preventive maintenance or testing be limited to those situations where the cause of inoperability has not been conclusively demonstrated to preclude the potential for a common mode failure. However, when such test 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.
Therefore, NNEC0's request that the testing required by the Millstone, Unit 3 TS be completed within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> is appropriate for complying with the intent
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i of GL 93-05. Since the staff agrees with the position taken in NUREG-1431,-
~NNECO's argument is acceptable.
The staff's evaluation of the specific TS changes proposed by NNECO follows.
. Change 1:
Section 3.8.1.1 l
Action Statement a: NNECO proposes to delete the following sentence:
" I f.
either diesel generator has not been successfully tested within the past 1
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.5 separately for each such diesel generator within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />."
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Action Statement e: NNEC0 proposes to delete the following sentences:
... demonstrate the OPERABILITY of the two diesel generators by sequentially performing Surveillance Requirement 4.8.1.1.2.a.5 on both diesel generators 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..." and "A successful test (s) of diesel generator OPERABILITY per Surveillance Requirement 4.8.1.1.2.a.5 performed under this Action Statement for the OPERA 8LE diesel generators satisfies the diesel generator test requirement of Action Statement a."
These proposed changes are in accordance with the recommendations of Section 10-1 of GL 93-05 and are acceptable.
Chance 2:
Section 3.8.1>.1 Action Statements b and c: NNEC0 proposes to delete the following clause:
...and if the diesel generator became inoperable due to any cause other than preplanned preventive maintenance or testing..."
It also proposes the addition of the following footnote:
"The OPERABILITY of the remaining diesel generator need not be verified if the diesel generator became inoperable due to:
(1) Preplanned preventive maintenance or testing, (2) An inoperable support system with no potential common mode failure for the remaining diesel generator, or (3) An independently testable component with no potential common mode failure for the remaining diesel generator."
These proposed changes are in accordance with the intent of Section 10-1 of GL 93-05 and are acceptable.
NNECO also proposes to delete the following footnote for Action Statements b and c because it believes it is unnecessary:
"This test is required to be completed regardless of when the inoperable diesel generator is restored to OPERABILITY." This footnote requires that if either EDG becomes inoperable the operability of the remaining EDG be tested by starting it within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> for Action Statement b and 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> for Action Statement c, regardless of when the inoperable EDG is restored to operability.
In GL 93-05, the staff states
. that this test will still have to be done if any potential common mode failure can be demonstrated.
In a conference call with NNECO on February 15, 1995, the staff wanted to know the reason for the deletion of the footnote.
NNECO stated that it believed that the new footnote given above essentially conveyed the same message as the existing footnote. The staff pointed out to NNECO that the new footnote did not address the situation of the inoperable EDG being restored to. service in less time than that imposed by Action Statement b or c.
The staff also pointed out that it had accepted an owners group proposal in September 1993, to remove the note from the new standard TS (NUREG-1431). The effect of this change is to reduce alternate EDG testing if the inoperable EDG is returned to operable status in less time than that imposed by the action statements. However, the element of common cause failure determination is captured in the Bases. The Bases will state that if the inoperable EDG is restored to operable status before the cause of the inoperability of the EDG is determined, the licensee will continue to evaluate the common cause failure possibilities.
This continued evaluation, however, is no longer under the time constraints imposed,by the Action Statements.
NNECO accepted the staff's suggestion and revised Bases 3/4.8.1 according to NUREG-1431 and submitted it on March 28, 1995.
NNECO also proposes to add the word "offsite" after the phrase "the remaining" and to delete the phrase "a or" from Action Statement c.
These changes are editorial and are acceptable.
Chance 3:
SR 4.8.1.1.2.a.6) and 4.8.1.1.2.b NNEC0 proposes to replace the words "...in less than or equal to 60 seconds..." in SR 4.8.1.1.2.b with the words "...in accordance with the manufacturer's recommendations..." The same words also will be added to SR 4.8.1.1.2.a.6).
The words "with a load greater than or equal to 4986 kW" will be inserted in both SRs.
These changes are in accordance with the recommendations of Section 10-1 of GL 93-05 and are acceptable.
Chance 4:
SR 4.8.1.1.2.o.7 NNEC0 proposes to replace the reference to SR 4.8.1.1.2.g.6)b) with a reference to SR 4.8.1.1.2.a.5) in SR 4.8.1.1.2.g.7 and associated footnote.
Additionally, the time requirement in the footnote to run the EDG for 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> to achieve normal operating temperature will be increased to 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />. A footnote is to be added to indicate that EDG loading for the 24-hour test may include gradual loading as recommended by the manufacturer.
These changes are in accordance with the recommendations of Section 10-1 of GL 93-05 and are acceptable.
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. Chance 5:
NNECO plans to change the placement of a footnote regarding the EDG prelube system from TS 4.8.1.1.2(a) and 4.8.1.1.2(b) to the main heading 4.8.1.1.2.
The proposed change will result in the prelube system being operable for all surveillance tests required by TS 4.8.1.1.2.
The existing footnote, " Testing shall be conducted in accordance with the manufacturer's recommendations regarding engine prelube and warmup procedures, and as applicable regarding loading requirements" is to be replaced by, "All planned starts for the purpose of these surveillances may be preceded by an engine prelube period."
These changes are consistent with NUREG-1431 and are acceptable.
Chance 6:
NNECO proposes to replace the term " ambient condition" with the term " standby conditions" in SR 4.8.1.1.2.a.5).
The term " standby conditions" will be inserted in SRs 4.8.1.1.2.g.4.b), 4.8.1.1.2.g.5), and 4.8.1.1.2.g.6)b) The term " standby conditions" more accurately describes the condition in which the EDGs are maintained, accounts for the continual operation of the jacket water and lube oil warming systems, and is used in NUREG-1431. The proposed changes are acceptable.
Chance 7:
NNEC0 proposes to delete the reference to speed (508 rpm) for the EDGs from SRs 4.8.1.1.2.a.5), 4.8.1.1.2.b, and 4.8.1.1.2.h.
These SRs specify, among other requirements, that after a start signal, the EDGs gradually accelerate to at least 508 rpm with generator voltage and frequency at 4160 +/- 420 volts and 60 +/- 0.8 Hz. The most significant parameters regarding these SRs are frequency, voltage, and time following the start signal; that is, the EDGs should be able to accept loads in proper sequence and continue to carry safety-related electrical loads within the required time after the start signal. NUREG-1431 deleted engine speed requirements. Therefore, the proposed change is acceptable.
Chanae 8:
NNECO proposes to add paragraphs to the Bases section 3.4.8 consistant with the revised Section 3.8.1.1.
The proposed changes were discussed in Chance 2 and because the Bases changes are consistent with the revised TS, the Bases changes are acceptable to the staff.
1 3.0
SUMMARY
The proposed changes will modify the requirement for operability testing of an EDG when the alternate EDG is inoperable, delete the requirement for operability testing of the EDGs when one or both offsite ac sources are 1
1
. Inoperable, eliminate fast loading of EDGs except for the 18-month test, and.
modify the hot restart test from the 24-hour loaded test run for the EDG. The staff examined and accepted this reduction in operability testing and modified surveillance requirements for the EDGs at power in GL 93-05, Section 10-1.
It found that although most 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. The licensee also proposes changes that are consistent with the improved Standard Technical Specifications (NUREG-1431), such as replacing current footnotes to SR 4.8.1.1.2 with a footnote that states, "All planned starts for the purpose of these surveillances may be preceded by an engine prelube period"; replacing the term " ambient condition" with " standby condition"; and eliminating the reference to EDG speed in various surveillance test acceptance criteria. These changes are acceptable.
4.0 STATE CONSULTATION
In accordance with the Comission's regulations, the Connecticut State official was notified of the proposed issuance of the amendment. The State official had no comments.
5.0 ENVIRONMENTAL CONSIDERATION
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 Comission has previously issued a proposed finding that the amendment involves no significant hazards consideration, and there has been no public comment on such finding (60 FR 8749). 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.
6.0 CONCLUSION
The Comission 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 en' dangered by operation in the proposed manner, (2) such activities will be conducted in compliance with the Comission's regulations, 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:
S. K. Mitra Date:
May 12, 1995
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