ML20042G982
| ML20042G982 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 05/10/1990 |
| From: | Keuter D SACRAMENTO MUNICIPAL UTILITY DISTRICT |
| To: | Larkins J NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| AGM-NUC-90-067, AGM-NUC-90-67, NUDOCS 9005160369 | |
| Download: ML20042G982 (3) | |
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J gouun SACRAMENTO MUNICIPAL UTILITY DISTRICT D 6201 S Street, P.o. Box 15830, Saceamento CA 958521830,(916) 452 3211-AN ELECTRIC SYSTEM SERVING THE HEART OF.CAUFORNIAf AGM/NUC 90-067 L
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May 10, 1990 i
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l U. S. Nuclear Regulatory Commission l
Attn: Document Control Desk l
J Hashington, DC 20555 l
= Docket No. 50-312 Rancho Seco Nuclear Generating.. Station j
L License No. DPR-54 REQUEST FOR TEMPORARY EXEMPTION FROM GENERAL DESIGN CRITERION 17 AS APPLICABLE TO USE OF DIESEL GENERATOR SETS AS PEAKING PONER SUPPLIES
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,q Attention: John Larkins Pursuant to U CFR 50.12, the District hereby requests a temporary exemption
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from the requirements of General Design Criterion (GDC) 17, " Electric Power Systems", as it applies to the use of standby power supply diesel generators i
to supply power to the regional electrical system during peak-load demand.
periods. He base this request on the special circumstances categorized'in subsections 50.12(a)(2)(ii), 50.12(a)(2)(iv), 50.12(a)(2)(v), and.
1 50.12(a)(2)(vi) of Part 50 as explained-below, f
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The :,pecific requirement from which we are seeking relief is the l
interpretation of GDC-17 included in Branch Technical: Position'ICSP-8 (PSB),
i "Use of Diesel-Generator Sets for Peaking", by reference in Standard _ Review i
Plan Section 8.3.1, "A-C Power Systems _(Onsite)".
These docu% nts restrict i
interconnection of onsite-and offsite power sources because of the potential l
l for common mode failure and the higher probability of coincident loss of-both-I offsite and onsite power sources. A main premise for-this position is;that-L onsite power sources are necessary to provide standby emergency power in-the j
l case of a design basis accident concurrent with a loss of all offsite power 1
sources.
It is our intent to ' operate three of. the four diesel generators,
.j onsite as peaking power unitt. upon receipt of NRC.and state approvals.- Hith' 1
the reactor at Rancho Seco defueledt and with the fuel in an inherently safe i
configuration, the' need for onsite emergency power sources-to supply loads-in -
j the event of accidents is greatly diminished.
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=As previously committed in our December 4, 1989 letter (AGM/NUC 89-261), one_
i diesel generator unit of the four units onsite is;being maintained.available to provide emergency powrc, should a fuel handling' accident.and/or-loss of i
offsite power occur.
These are the two credible accidents when'defueled. The public health and safety is servta'by our commitment to maintain one diesel 1
i' generator _available. Maintaining. additional diesel generator!. in running 4
conditionJoperating or in readiness to do.so, rather: than placing:them in; 4
layup provides.an additional benefit to. health and safety of the public.
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' i' 9005160369 900510 PDR-ADOCK 05000312 1
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l RANCHO SECo NUCLEAR GENERATING STATION O 14440 Twin Cities Road 'Horaki, CA 95638 9799;(209) 333 2935 J
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John Larkins AGM/NUC 90-067 I
y He anticipate that the only changes necessary will be procedural in nature.
The alignment of the electric power system switchgear will be similar to the-1 alignment used when testing the diesel generators. As such, there is no affect on remaining plant equipment when compared to placing the three diesel generators in lav-up rather than using them as peaking power supplies.' He have not identi'L1 any plant modifications which would be necessary to accomplish this < unge in usage e the diesels.
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Should any repairs to the diesel generators b9 necessary while in use as.
peaking power units, qualified partr will be used or detailed records of-any non-qualified parts usage will be ks:st.
I The time span we propose to make our three unnecessary diesel generators (i.e., not being maintainad-as available to-supply onsite emergency loads) l available to our dispatcher to supply power to the power grid is during the current defueled condition.
The District is in the process of preparing a Dacommissioning Plan for submittal to the NRC for approval.
While this r vess is proceeding, it would be of benefit to the District to make'the m'sels available for power production.
The alternative is to place the-F. 3e1 generators in-layup. While not deleterious, layed up diesel generators k..ld provide no benefit to our ratepayers.
The.special circumstances present concerning this request are as follovs:-
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Regardina 10 CFR 50.12(a)(2)(ii)
The restriction on usage of diesel generators to supply electrical system power during peak load demand periods while Rancho Seco is defueled does not serve the underlying purpose of GDC-17.
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underlying purpose of GDC-17 in the event of postulated accidents is to:
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l 1) assure fuel design limits and designLconditiens of the-reactor coolant pressure boundary are not exceeded; R
2) maintain core cooling; 3) ensure containment-integrity;-
4) maintain other vital functions.
With the reactor defueled, fuel design limits cannot-be reached, the reactor coolant system is not in use, there is no core to cool and i
a containment integrity is not required. The only'" vital" functions that electric' power systems must support are protection of spent fuel and control of radiological releases.
The purpose of the emergency electric power systems is met by maintaining one onsite.
diesel generator unit available should a credible emergency occur.
J Using the very conservative assumptions of ANSI /ANS 5.1-1979 and Branch Technical Position ASB-9-2,.the time to boil following a loss of spent fuel cooling is more than 4 days in June of 1990.
From this it is apparent that emergency electrical power is not critical to responding to a credible emergency.
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,' John.Larkins-AGM/NUC 90-J67-2.
.Re.gardina 10 CFR ' 50.12(a)(2)(iv)-
By maintaining diesel generators;in running condition rather than layup allows.the operators to have the flexibility of additional diesel ' generators for emergency service should an emergency occur.
This is of benefit to the health and safety-of the public. By maintaining one diesel generator'"available" for emergency service, the public health and satety is adequately served. = Additional benefit-is provided by maintaining'the remaining three diesels in
-running condition.
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Reaarding 10 CFR 50.12(a)(2)(v)
This request is temporary in nature and does not result in any:
noncompliance with GDC-17 as applicable to Rancho Seco in'other than; the defueled condition.; Rancho Seco has complied with GDC-17:in the-
.past and as stated above, we request exemption only'for the time we are in our current defueled condition.
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Reaardina 10 CFR 50.12(a)(2)(vi)
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The District has removed all fuel from the. reactor vessel, has begun placing unnecessary systems in layup condition, anfis planning to
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decommission the-facility, upon NRC approval of.the Rancho Seco Decommissioning Plan (to be submitted to the NRC by June.1991).- The:
i GDC are intended to apply to operating power plants. The District-9 nas no plans to operate Rancho Seco again:as a. nuclear facility.
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The public interest would not be served by restricting usage of diesel generators while defueled and preparing the decommissioning j
plan.
The above noted special circumstances will, we trust, provide the necessary l
basis for granting'our request. Your timely consideration of this request-j would be appreciated. Members of your staff with questions requiring additional information or clarification may contact Mr. Jerry Delezenski at (209) 333-2935, extension 4914.
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. Sincerely, I
hb Dan R. Keuter Assistant General Manager i
Nuclear cc:
J B. Martin, NRC, Halnut' Creek A. D'Angelo, NRC, Rancho Seco j
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