ML20073T277
| ML20073T277 | |
| Person / Time | |
|---|---|
| Site: | Arkansas Nuclear  |
| Issue date: | 05/03/1983 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20073T273 | List: |
| References | |
| NUDOCS 8305110173 | |
| Download: ML20073T277 (3) | |
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UNITED STATES
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WAsMNGTON, D. C. 20555
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~f SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION SUPPORTING AMENDMENT NO. 45 TO FACILITY OPERATING LICENSE N0. NPF-6 ARKANSAS POWER & LIGHT COMPANY ARKANSAS NUCLEAR ONE, UNIT 2 DOCKET NO. 50-368 Introduction By letter dated August 12, 1980, Arkansas Power and Light (AP&L) proposed a change to the Arkansas Nuclear One, Unit 2 (ANO-2) Technical Specifications (TS) to clarify and modify the emergency diesel generator load block application timing criteria (Surveillance Requirement 4.8.1.1.2.c.2).
These criteria determine the timing at which the emergency loads are automatically connected to the emergency diesel generator in the event of an accident.
Following NRC review of this proposal, in a letter dated January 17, 1982 we suggested several options to resolve a difference in interpretation.
AP&L responded to these options by letter dated February 3,1983, with a revised, superseding application.
Discussion AP&L proposed a Technical Specification change to clarify and modify the emergency diesel generator load block application timing criteria (Surveillance Requirement 4.8.1.1.2.c.2) for Arkansas Nuclear One, Unit 2 (ANO-2), by letter dated February 3, 1983.
Presently this requirement reads:
" Verifying that the automatic sequence time delay relays are OPERABLE with the interval between each load block within i 10% of its design interval." AP&L proposes to change the requirement to read:
" Verifying that the automatic sequence time delay relays are OPERABLE at their setpoint 10% of the elapsed time for each load block."
In order to support the proposed technical specification change, AP&L contracted with their diesel generator supplier, Colt Industries, to perform a study to demonstrate that the new surveillance requirement would meet the guidelines of NRC Regulatory Guide (R.C.) 1.9.
Evaluation Colt Industries performed the study to determine whether load sequencing under the proposed technical specification change would meet the following provisions i
of R. G.
1.9, Section C.4.
The diesel generator unit design should be such that at no time during l
the loading sequence should the frequency and voltage decrease to less
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than 95 percent of nominal and 75 percent of nominal, respectively Frequency should be restored to within 2 percent of nominal, and voltage should be restored to within 10 percent of nominal within 60 percent of each load-sequence time interval B305110173 830503 PDR ADDCK 05000368 P
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2 Three scenarios were examined that represented different contingencies with somewhat different step loadings.
The three scenarios studied were:
loss of coolant accident (LOCA), main steam line rupture (MSLR), and loss of offsite power (LOP).
The following Table 1 lists the setpoint and bandwidth of each of the twelve ANO-2 sequencing steps.
Table 1 Step Relay Setpoint (sec)
Bandwidth (sec) 0 1
0 2
- 5. 5 4.95 - 6.05 3
10 9.0 - 11.0 4
15 13.5 - 16.5 5
20 18.0
- 22.0 6
25 22.5 - 27.5 7
50 45.0 - 55.0 8
60 54.0 - 66.0 9
70 63.0 - 77.0 10 80 72.0 - 88.0 11 90 81.0 - 99.0 12 120 Manually Operated Of particular concern is the effect on the frequency and voltage of the diesels when, due to the time variance of each loading step, there might be an overlap of two steps.
This condition is possible in steps 7 - 11.
Colt Industries considered the possibility of this worst case scenario and also included steps 5 & 6 in this study due to the closeness of their sequencing.
Table 2 below summarizes the maximum voltage and frequency dips, and the times necessary to recover to 90 percent of nominal voltage and 98 percent of nominal frequency for each scenario.
("
Table 2 Time to Time To Voltage Dip 90% Recovery Frequency Dip 98% Recovery Scenario
(%)
(sec)
(%)
(sec)
LOCA 21.0
.33 1.22 1 0.001 MSLR 21.0
.33 1.22 1 0.001 LOP 21.0
.33 1.22 1 0.001 Overlap LOCA 21.0
.33 1.22 1 0.001 MSLR 21.0
.33 1.22 1 0.001 LOP 21.0
.33 1.22 1 0.001 R. G. 1.9, Section C.4., deals with voltage and frequency recovery times as a percentage of each load-sequence time interval.
When two load steps overlap due to relay timer variance, this section could be violated.
However, if the overlapping steps are considered as a single step, then no violation would occur.
Since there should not be a diesel overload and trip even with the possibility of two load sequencing steps occurring at the same instant, we find the proposed change to ANO-2's technical specification to be acceptable.
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- Environmental Consideration We have determined that the amendment does not authorize a change in effluent types or total amounts nor an increase in power level and will not result in any significant environmental impact.
Having made this determination, we have further concluded that the amendment involves an action which is insignificant from the standpoint of envircnmental impact and, oursuant to 10 CFR 551.5(d)(4), that an environmental impact statement or negative declaration and environ-mental impact appraisal need not be prepared in connection with tne issuance of this amendment.
Conclusion We have concluded, based on the considerations discussed above, that:
(1) because the amendment does not involve a significant increase in the probability or consequences of an accident previously evaluated, does not create the possibility of an accident of a type different from any evaluated previously, and does not involve a significant reduction in a margin of safety, the amendment does not involve a significant hazards consideration, (2) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, and (3) such activities will be conducted in compliance with the Commission's regulations and the issuance of this amendment will not be inimical to the common defense and security or to the health and safety of the public.
Date: May 3, 1983 Principal Contributors:
E. C. Tourigny R. P. Mullikin O
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7590-01 UNITED STATES NUCLEAR REGULATORY COMMISSION DOCKET NO. 50-368 ARKANSAS POWER & LIGHT C0!1PANY NOTICE OF ISSUANCE OF AMENDMENT TO FACILITY OPERATING LICENSE The U. S. Nuclear Regulatory Commission (the Commission) has issued Amendment No. 45 to Facility Operating License.No. NPF-6 issued to Arkansas Power & Light Company (the licensee), which revised the Technical Specifica-tions for operation of Arkansas Nuclear One, Unit 2 (the facility), located in Pope County, Arkansas. The amendment was effective as of the date of issuance.
l The amendment clarifies and modifies the emergency diesel generator load block application timing criteria.
The applications for the amendment comply with the standards and requirements of the Atomic Energy Act of 1954, as amended (the Act), and the Commission's rules and regulations. The Commission has made appropriate findinas as required by the Act and the Commission's rules and regulations in 10 CFR Chapter I, which are set forth in the license amendment.
Prior public notice of the amendment was not required since the amehdment does not involve a significant hazards consideration, i
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7590-01 The Conmission has determined that the issuance of the amendment will not result in any significant environnental impact and that pursuant to 10 CFR 551.5(d)(4) an environnental impact statenent or negative declaration and environnental inpact aopraisal need not be prepared in connection with the issuance of the amendment.
For further details with respect to this action, see (1) the applications for anendment dated August 12, 1980 and February 3,1983,(2) Amendnent No.45 to Facility Operating License No. NPF-6, and (3) the Connission's related Safety Evaluation.
These items are available for public inspection at the Commission's Public Document Room at 1717 H Street, N.tl., Washington, D.C.
20555 and at the Tonlinson Library, Arkansas Tech University, Russellville, Arkansas 72301.
A copy of itens (2) and (3) may be obtained upon request addressed to the U.
S. Nuclear Reculatory Commission, 4ashington, D.C.
20555, Attention:
- Director, Division of Licensing.
Dated at Bethesda, Maryland, this 3rd day of May,1983.
FOR THE NUCLEAR REGULATORY COMMISSION t
r,
- _i Charles M. Trammell, Acting Chief Operating Reactors Branch #3 Division of Licensing i
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