ML20204J275
| ML20204J275 | |
| Person / Time | |
|---|---|
| Site: | Hatch  |
| Issue date: | 10/19/1988 |
| From: | Hairston W GEORGIA POWER CO. |
| To: | NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM) |
| References | |
| HL-110, NUDOCS 8810250079 | |
| Download: ML20204J275 (6) | |
Text
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' Georg a Ftmer Compey.
33J P+cnont Avenue
- . Ananta. Gacrg a 30308 Te epore 404 526 6526 i
Ma::rg Ad@ess Post Off.ce Oca 4'AS
' Attaria. Georg:a 30302
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l W. O. Hairstort. Ill rwavern Mtre s>s. 'It M,or Vice Prescerd NaCleaf OpertNvs HL-110 0510I X7GJ17-H220 October 19, 1988 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Hashington, D.C.
20555 PLANT HATCH - UNITS 1, 2 NRC 00CKETS 50-321, 50-366
-f OPERATING LICENSES DPR-57, NPF-5 REQUEST FOR ADDITIONAL INr0RMA110N REGARDING IMPLEMENTATION OF ANTICIPATED TRANSIENTS HITHOUT SCRAM (ATHS) MODIFICATIONS Gentlemen:
In response to a verbal request of the NRC, additional information regarding Georgia Power Company's (GPC) impleaentation of modifications i
required by the ATHS rule,10 CFR 50.62, is provided in the enclosure.
This informatior: supplements GPC's previous letters dated M uch 4, 1987, I
and April 29, 1988.
r The enclosed responses have been discussed with L. P. Crocker _ and H.
C. Li of the NRC staff.
It is GPC's understanding that these responses, with one exception, are acceptable to the NRC staff.
Specifically, while t
the NRC expressed concerns regarding the scope of testing at power of the Alternate Rod Insertion systern, GPC believes, as detailed in the enclosure, that the current testing scope is acceptable and achieves compliance with the ATHS rule.
l If you have any further questions in this regard, please contact this office at any time.
[
88 Sincerely, PDk025b9Belo,,
A 05000321-a). A Lh-W. G. Hairston, llI CLT/ac
Enclosure:
Request for Additional Infermation Ao6S c: (see next page)
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Geogia Power m U. S. Nuclear Regulatory Commission October 19, 1988 Page Two l
l c: Georaia Power Comoany l
Mr. H. C. Nix, General Manager - Hatch l
Mr. L. T. Gucwa, Manager, Licensing and Engineering - Hatch GO-NORMS U.S. Nuclear Regulatory Commission. Washinaton. C.C.
Mr. L. P. Crocker, Licensin", 'roject Manager - Hatch U.S. Nuclear-- Regulatory Commission. Reaion U Dr. J. N. Grace, Regional Administrator Mr. J. E. Henning, Senior Resident Inspector - Hatch l
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Georgia Power n\\
ENCLOSURE l
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PLANT HATCH - UNITS 1, 2 NRC DOCKETS 50-321, 50-366 OPERATING LICENSES DPR-57, NPF-5 REQUEST FOR ADDITIONAL INFORMATION REGARDING IMPLEMENTATION OF ANTICIPATED i
TRANSIENTS HITHOUT SCRAM (ATHS) MODIFICATIONS l
ALTERNATE R00 INSERTION (ARI) IMPLEMENTATION HRC Item 1:
Describe the functioning of the manual initiation switches in the Plant Hatch ARI design.
GPC Resoonse:
Two ARI manual initiat:. control switches, IC11-SIA and B, are located on control room panel lH'i P603.
The control switches are pushbutton switches with collars.
To arm the ARI logic, ths collars of both switches must be rotated from the normal position to the armed i
position.
Confirmation of the arming of the ARI logic is provided by the l
alarming of the ARI MANUAL INITIATION IN ARMED POSITION annunciator.
To manually actuate the ARI
- logic, both switches must be depressed, i
Confirmation of the manual initiation of the ARI logic is providtd by the alarming of the ARI INITIATED annunciator and the illumination of several other indicating lights.
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NRC Itam 2:
The ATHS rule guidance states that the ARI system should be l
testable at power.
Describe the scope of ARI testing that is performed
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while at power.
Specifically, are the relays which actuate the ARI valves (final actuation devices) tested while at power?
P GPC Resoonse:
As described in GPC's April 29, 1988 letter, the Plant
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Hatch ARI uses a redundant two-out-of-two logic arrangement.
Ihit allows j
maintenance, testing, or cai,Pation while at power of the system logic and instrumentation up to the Nnal trip devices (four ARI actuation relays and their associated soleroid valves).
The four ARI actuation relays thus are not tested while et power.
Each individual level and pressure instrument can be tested during plant operation without initiating the ARI system, since two level or two l
pressure signals must be present in one channel to complete the signal.
Therefore, bypasses are not required for this design approach.
If the conditions for ARI initiation occur during sensor maintenance, either the remaining redundant active level channel or pressure channel would be available to initiate the system.
This design configuration was specifically ref erenced as an acceptable means of meeting the testable at power requirement in Section 6.2, Item 10, of the NRC Safety Evalut'lon of Licensing Topical Report NEDE-31096-P.
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05101 E-1 10/19/88 l
HL-110 l
Georgia Ponel ENCLOSURE (Continued)
REQUEST FOR ADDITICNAL INFORMATION REGARDING IMPLEMENTATION OF ANTICIPATED TRANSIENTS HITHOUT SCRAM (ATHS) MODIFICATIONS GPC does not believe extending the testing while at power to cover the four ARI actuation relays is neces:ary to achieve full compliance with the ATHS rule.
Currently, in addition to the described scope of testing while at power, which is performed at least once every 31 days, a complete Logic System Functional Test (LSFT) is performed on the ARI system at least once per operating cycle.
The LSFT exercises all portions of the ARI logic; the ARI actuation relays are energized to initiate an ARI scram.
This scope and frequency of testing for ARI while at power and during situtdown are consistent with the testing scope for other comparable systems, many of which, unlike ARI, are required to be safety-related.
If testing of the four ARI actuation relays while at power were to be required, GPC would have to install test switches which would block the actuation signals to the ARI solenoid valves during surveillance testing.
As an alternative, GPC would possibly pursue modifying the procedures to test ARI at power to include lif ting specified leads to accomplish the same function as a
test switch.
GPC views both alternatives as undesirable, since they increase the possibility of human error or equipment malfunction preventing ARI from functioning when needed.
The improvement in ARI reliability due to the ability to test the system more frequently does not justify the introduction of these new failure mechanisms.
Based on the above considerations, GPC concludes that the current scope of ARI testing while at power is acceptable and achieves compliance with the ATHS rule.
NRC Item 3:
Describe how GPC intends to address the ATHS rule requirement that each boiling water reactor have an ARI that is diverse (from the reactor trip system (RTS)) from censor output to the final actuation device.
Specifically, the NRC staff position on ARI versus RTS diversity requires a diverse manufacturer for the analog transmitter trip unit (ATTU) circuit boards to assure sufficient diversity between ARI and RTS.
GPC Resconse:
Currently, GPC uses General Electr(.c (GE) ATTU circuit boards in both the Plant Hatch ARI system and the Reactor Protection System (RPS) to provide the reactor pressure and reactor water level trip signals.
GPC participated in the BHR Owner's Group (BHROG) activity so address the issue of ARI and RPS trip unit diversity.
GPC concurred with the position expressed in the BWROG letter to the NRC dated June 28, 1988, that the ARI design provides a diverse logic circuit and valve design from RPS which addresses the majcir contributors to common cause 0510I E-2 10/19/88 HL-110
Georgia Poner d ENCLOSURE (Continued)
REQUEST FOR ADDITIONAL INFORMATION REGARDING IMPLEMENTATION OF ANTICIPATED TRANSIENTS HITHOUT SCRAM (ATHS) MODIFICATIONS failure; therefore, manufacturer diversity of the trip units is not necessary to meet the intent of the ATHS rule.
However, the NRC staff has continued to maintain its position that manufacturer diversity is required, as noted in the NRC response, dated i
August 8,
- 1988, to the referenced BHROG letter.
Therein the NRC encouraged licensees to provide a maximum effort to satisfy the diversity requirements.
GPC will agree to replace the GE ATTU circuit boards in the ARI system with circuit boards manufactured by Rosemount.
This modification will be completed by the end of the Plant Hatch Units 1 and 2 refueling outages currently scheduled, respectively, for 1990 and 1991.
RECIRCULATION PUMP TRIP (RPT) IMPLEMENTATION NRC Item 1:
In GPC's April 29, 1988, letter responding to NRC tuestions on GPC's implementation of the ATHS rule requirements, GPC agreed to upgrade the RPT system.
The upgraded RPT will duplicate the RPT design used at Brunswick Steam Electric Plant (BSEP) by Carolina Power and Light Company (CP&L), as documented in CP&L's letters to the NRC of April 14, 1987 July 22, 1987, and November 13, 1987.
Provide further details on the implementation of the upgraded RPT at Plant Hatch which demonstrates that the reliability analysis performed cm the BSEP RPT is applicable to the Plant Hatch upgraded RPT.
GPC Response:
GPC plans to upgrade the existing Plant Hatch RPT design by modifying the actuation logic so the current redundant two-out-of-two logic used to actuate ARI will also be used to simultaneously trip both recirculation pumps.
This modification will be completed by the end of the Plant Hatch Units 1 and 2 refueling outages currently scheduled, i
respectively, for 1990 and 1991.
The CP&L reliability analysis performed for the BSEP RPT design is directly applicable to the Plant Hatch upgrided RPT design.
The ARI/RPT trip signal will actuate a single trip coil in each recirculation systen motor generator (H/G) set drive motor breaker.
The upgraded Plant Hatch RPT design will duplicate the BS':P RPT design.
As such, the upgraded design will differ from the Monticello RPT design, referanced in Section 7.1 of the NRC Safety Evaluation of Licensing Topical Report NEDE-31096-P, in the same manner as the CSEP RPT design, Monticello trips the recirculattan M/G set field breaker using redundant trip coils; whereas the BSEP and Plant Hatch designs trip the M/G set drive motor breaker (main 4-kV breaker).
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Ge rgialbwer A ENCLOSURE (Continued)
REQUEST FOR ADDITIONAL INFORMATION REGAADING l
IMPLEMENTATION OF ANTICIPATED l
Ifg 31ENTS WITHOUT SCRAM (ATHS) MODIFICATIONS l
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The CP&L reliability analysis demonstrated that in both the Monticello
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and BSEP designs, the circuit breaker (field breaker model AKF-2-25 and i
4160-V breaker, respectively) failures dominate.
Therefore, the analysis focused on the relative unavailabilities of the two breakers.
The CP&L analysis demonstrates that the 4160-V breaker is more reliable than the model AKF-2-25.
The use of the more reliable 4160-V breaker in the BSEP and Plant Hatch RPT offsets the use of the two trip coils in the Monticello RPT desiga, resulting in the BSEP/ Plant Hatch RPT design being at least equivalent in reliability to the Monticello RPT.
It should be noted that the specific manufacturer of the trip units (GE i
or Rosemount) used in ARI/RPT initiation logic does not impact the l
results of the CP&L RPT reliability study, since generic failure data were used for those components in the analysis.
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0510I I-4 10/19/88 HL-110
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