ML20011E077
| ML20011E077 | |
| Person / Time | |
|---|---|
| Site: | Fort Calhoun  |
| Issue date: | 01/30/1990 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20011E075 | List: |
| References | |
| NUDOCS 9002070242 | |
| Download: ML20011E077 (4) | |
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.%'g UNITED STATES I
NUCLEAR REGULATORY COMMISSION wAssworow. o. c. rosos 7,
SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED T0, PROPOSED REVIS_ ION TO TECHNICAL SPECIFICATION OMAHA PUBLIC POWER DISTRICT i
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FORT CALHOUN STATION, UNIT N0. 1 l
I DOCKET NO. 50-285 i
1.0 INTRODUCTION
By letter dated November 15 1989, Omaha Public Power District 'the licencee of the Fort Calhoun Station, su,bmitted a proposed Technical SpeciIication (TS) change request. The change request pertains to the action required for inoperability of the 161 kV transmission line. The changed wording would be as follows:
2.7(2)n. The 161 kV transmission line may be out of service and unit caeration may continue in the Power Operation Condition (Mode 1) if tie 345 kV system and both diesel generators are operable. During the time the 161 kV power source is unavailable, the requirenent for the performance of monthly surveillance tests on the diesel generators or any other test that could challenge the emergency actuation of the diesel generators is deferred until seven (7) days after restoring the 161 kV power source.
At Fort Calhoun, the 161 kV transmission line is the only power source to the house service transformers (station startup transformers) TIA-3 and TIA-4.
The action statement pertaining to inoperability of these transformers is as follows:
2.7(2)b.. House service transformers TIA-3 or TIA-4 (4.16 kV) may be inoperable for up to one week. House service transforcers TIA-3 and TIA-4 (emphasis added) may be inoperable for up to 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> provi"dB the operability of both diesel generators is demonstrated imnediately, and the NRC is notified immediately and a report is submitted to the NRC as specified in Section 5.6 with an outline of the plans for prompt restoration of off-site power and the additional precautions to be taken while the transformers are out of service.
The proposed TS change, 2.7(2)n., appears to allow continued operation far beyond the 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> allowed by 2.7(2)b. However, the licensee has not requested achangeto2.7(2)b.
The NRC staff, therefore, contacted the licensee by telecon to discuss this apparent discrepancy. During this telecon, the licensee stated that they would look into the matter and call us back.
In subsequent telecons, the licensee first took the position that the house service transformers were not considered inoperable when the 161 kV transmission line was inoperable.
e Later they took the position that even if the transforrers were inoperable due 9002070242 900130 ADOCK0500g5 DR
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took precedent over 2.7(2)b. We took issue with this interpretation, ststing that if a power source is inoperabic, it is the responsibility of the licensee to know what other equipment becones inoperable and to apply the appropriate TS.
The' confusion results in part because of the present TS action statement 2.7(2)n. which states the following:
2.7(2)n. The 161 kV transmission line may be out of service and unit cperation may centinue or the reactor may be restarted from a hot shut-down condition if (i) operability of the remaining source is immediately verified and (ii) immediate notification is made by telephone or tele-i graph to the Director of the NRC Regional Office in Arlington, Texas of the loss and of the plans to restore the electric power system to its full capability.
In previous instances when the 161 kV line became inoperable, the NRC staff, upon being notified of the circumstances, apparently allcwed continued operation of'the plant.
In one case continued operation was allowed for a period of seven days. Apparently the NRC staff considered the 24 hcur limit specified by the action statement 2.7(2)b., but waived the 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> requirement under the specific circumstances at the time. As a result, the licensee has apparently concluded that 2.7(2)b. does not apply when the 161 kV line is inoperable.
Further confusion arises because of the basic structure of the Technical Specifications involved. TS2.7(1)a.through1.isalistofminimumrequire-
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ments(limitingconditionsforoperation)whichmustbemetbeforethereactor is heated above or maintained above 300' F.
TS2.7(2)a.throughn. allows exceptions for given time periods to each (but only one at a time) of the minimum requirements if the reactor is critical. These are similar to the action statements of the TS for newer plants. There is a one to one 2.7(2)pondencebetweentheTS2.7(1)listandtheTS2.7(2)listexceptforTS corres
- n. which has no direct correspondence in the minimum requirement list, i.e., there is no minimum requirement pertaining to the 161 kV transmission line. Therefore, presumably this action applies to 2.7(1)b. which specifies the minimum requirement for the house service transformers TIA-3 ar.d TIA-4 However, the house service transformers have another action statement, i.e.,
2.7(2)b.thusresultingintwoactionstatements. These two action statenents do not conflict with each other and can be applied simultaneously under the t
L present TS. However, the licensee is taking the position that if the 161 kV lite is inoperable, the fact that the house service transformers are inoperable does not need to be considered because of wording in the TS that only one of the TS 2.7(2) items (i.e., a. through n.) are allowed. Clearly the intent is l
that only one of the minimum requirements may be deviated from at a time.
We suggested by telecon that the action statements for the 161 kV line and the hcuse service transformer inoperability be combined into the action statement 2.7(2)b.toeliminateconfusion. However, the licensee requested a safety evaluation indicating why we cannot accept their proposed TS change.
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, s 2.0 EVALUATION We find that the existing TS 2.7(2)n. is not necessary or desirable.
It is not needed because the inoperability of the 161 kV transmission line is already covered by the inoperability of the transformers which have no power source other than the 161 kV line.
It is undesirable because this duplication is creatingconfusionattotheneedforandintentofTS2.7(2)n. We do not know when or why TS 2.7(2)n. was added to the TS 2.7(2)a. through m. list. However, there is evidence as discussed previously that the relationship of this TS addition with the other parts of TS 2.7 was not fully considered or understood.
Inaddition,thereisanerrorwithinTS2.7(2)n.itself. TS 2.7(2)n. contains
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the phrase "the reactor may be restarted from a hot shutdown condition if -- ".
The licensee noted this error in their November 15, 1989 operational standpoint, in that it is not possible to start the reactor when the 161 kV line is out of service. We reiterate the error here to show that the other parts of TS 2.7 were not properly considered when TS 2.7(2)n. was added. TS2.7(2)contains the phrase "the following conditions will be. allowed after (emphasis added) the reactor has been made critical." Yet,2.7(2)n.which'isapartof2.7(2) discusses restarting the reactor from hot shutdown.
The proposed TS change corrects the above described error but retains 2.7(2)n.
which is not needed and enforces the confusion of the existing TS in that it puts no limit on the amount of time that the 161 kV transmission line may be out of service. The wording which would permit the monthly surveillance tests to be deferred indicates that the transmission line would be allowed to be out of service for an extended period of time.
This conflicts with the other TS requirement which requires the reactor to be shut down within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> unless l
permissien is granted by the NRC to continue operation with both house service transformers TIA-3 and TIA-4 inoperable. When the 161 kV line is inoperable, which is equivalent to TIA-3 and TIA-4 being inoperable, there is only one (delayed) offsite source available and the plant does not meet GDC-17 requirements.
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Operation urder these conditions rust therefore be limited.
The licensee's position that the present TS allows the plant to continue to operate for en indefinite time period when the 161 kV line is inoperable is not i
persuasive and is unreasonable considering the 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> limit that the plant may l
continue to operate when the house service transformers are inoperable.
3.0 CONCLUSION
We find the licensee's proposed TS change, which ap)arently wculd be interpreted as allowing the plant to continue to operate with tie 161 kV transmission line inoperable for an indefinite period without even notifying the NRC, to be unacceptable.
WebelievethatTS2.7(2)n.shouldbeeliminatedandrevisionofTS2.7(2)b.
considered. We offer the following TS taken from another plant of similar vintage for use as a guideline.
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Start-up transformer 1-2(2400 V) may be inoperable for up to 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> provided the operability of both diesel generators is demonstrated inmediately. Continued operation beyond 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> is permissible provided that a report is sent to the NRC immediately with an outline of the plans 4
for prompt restoration of the start-up transforver and the additional precautions to be taken while the transformer is out of service, and continue operating until notified differently by the NRC.
r Dated: January 30, 1990 l
Principal Contributor:
A. Toalston d
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