ML20072N573
| ML20072N573 | |
| Person / Time | |
|---|---|
| Site: | Diablo Canyon  |
| Issue date: | 08/23/1994 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20072N545 | List: |
| References | |
| NUDOCS 9409060198 | |
| Download: ML20072N573 (4) | |
Text
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[q UNITED STATES j. IkI() j NUCLEAR REGULATORY COMMISSION Q g gi f
WASHINGTON. D.C. 20556-0001 g '.s.-....f LAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. 93 TO FACILITY OPERATING LICENSE NO. DPR-80 l
AND AMENDMENT NO.
92 TO FACILITY OPERATING LICENSE N0. DPR-82 PACIFIC GAS AND ELECTRIC COMPANY 1
DIABLO CANYON NUCLEAR POWER PLANT. UNITS 1 AND 2 DOCKET NOS. 50-275 AND 50-323 l
1.0 LNTRODUCTION By letter of December 8,1993, Pacific Gas and Electric Company (or the J
licensee) submitted a request for changes to the Technical Specifications (TS).
The proposed amendments would revise TS 3/4.8.1, "A.C. Sources" to increase the required quantity of emergency diesel generator (EDG) fuel oil stored in the engine-mounted tank (day tank) from 200 gallons to 250 gallons.
The license amendment also proposed to revise TS 3/4.7.11, " Area Temperature Monitoring," and 3/4.8.1 to remove references to a five EDG configuration due to the installation of the sixth EDG.
2.0 BACKGROUND
Diablo Canyon Power Plant (DCPP) Units 1 and 2 have six EDGs to provide emergency t.C. power in the event of a loss of offsite power (LOOP) event.
Three EDGs are dedicated to each unit.
The function of the EDGs is to provide sufficient A.C. power for the operation of emergency systems and engineered safety features (ESF) during and following the shutdown of the reactor in the event that offsite power sources are not available.
TS 3.8.1.1.b.l. and 3.8.1.2.b.l. currently require a minimum inventory of 200 gallons of fuel oil to be maintained in each EDG day tank.
The fuel oil maintained in each day tank is used for the start and the initial operation of its associated EDG.
Additional fuel oil is transferred from the storage tanks via the diesel fuel oil storage and transfer system to replenish the day tanks as required.
The diesel fuel oil storage and transfer system at DCPP consists of two redundant transfer pumps, two redundant supply headers, two common storage tanks with a nominal capacity of 40,000 gallons each, and six EDG fuel oil day tanks with a nominal capacity of 550 gallons each.
Each EDG day tank has sufficient capacity for its associated EDG for 2) hours of full-load operation.
Each EDG day tank also has two separate, redundant transfer pump start-stop level switches. When the fuel oil level in the day tank reaches the low-level set point, the level switch automatically starts a transfer pump and opens the supply header solenoid valve corresponding to the respective 9409060198 WOOO3 PDR ADOCK 05000275 p
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transfer pump. The start settings for the level switches are slightly different from each other so as to allow one as a backup.
A direct engine-driven positive displacement fuel oil booster pump delivers fuel oil to the engine injection system, taking suction from the base-mounted day tank and passing the oil through two duplex absorbent-type filters.
A 10-gallon fuel oil priming tank ensures priming of the fuel oil booster pump suction line.
System instrumentation and control is provided on the tanks and pumps as follows:
(1)
The base-mounted day tanks have two separate redundant transfer pump start-stop level switches.
Each level switch starts a transfer pump and opens the supply header solenoid valve corresponding to the respective transfer pump, A or B.
The start setting for the header A level switches is slightly different from those for header B, allowing one to be a backup.
(2)
The start of transfer pump A or B is indicated both locally and in the control room.
(3)
Local controls at each diesel generator and manual crosstie valving between headers allow manual starting of either transfer pump and filling of the base-mounted day tanks from either header system A or B.
(4)
High-and low-level alarm switches are installed on all base-mounted day tanks that activate alarms both locally and in the control room to alert the operators.
(5)
High-and low-level alarm switches are installed on both fuel oil storage tanks that will activate alarms in the control room.
Additionally, dipstick-type indicators are provided on each storage tank.
Each EDG day tank at DCPP contains a low-level alarm. The low-level alarm is set (including instrument inaccuracy and measurement uncertainty) above the current TS required minimum contained volume. The absence of a low-level alarm annunciation is used to verify the fuel level in the day tank in accordance with Suiveillance Requirement 4.8.1.1.2a.1).
The transfer pumps automatically start abcve the TS required volume.
Therefore, normal EDG operation will result in day tank levels well above the TS minimum.
3.0 EVALUATION The licensee indicated that the basis of the current 200-gallon requirement was based on a contained volume and relates to the original transfer pump start set points.
ANSI N195-1976, Section 6.1, indicates the following regarding day tank minimum required volume.
Each diesel shall be equipped i
with day or integral tank or tanks whose capacity is sufficient to maintain at i
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- i least 60 minutes of operation at the level where oil is automatically added to the day or integral tank or tanks.
This capacity shall be based on the fuel consumption at a load of 100% of the continuous rating'of the diesel plus a j
minimum margin of 10% (the 10% margin is applied to the EDG's load; i.e., the 1
capacity of the day tank is based on 110% of the continuous rating).
With unusable volume accounted for, the current 200-gallon requirement provides sufficient fuel oil for approximately 50 minutes of EDG operation at full load without makeup fuel.
The proposed EDG day tank TS minimum of 250 contained gallons ensures adequate fuel oil for a nominal one hour of operation at rated lohd (2600 kW) and provides additional conservatism.
One hour is adequate time for an operator to take corrective action to restore the fuel oil supply to the affected day tank.
Verification of meeting the proposed EDG day tank TS minimum of 250 contained gallons will be provided by _
the EDG day tank low-level alarm.
Westinghouse Standard TS Bases states that the day tank TS minimum contained volume is based on providing adequate fuel oil for a minimum of one hour of EDG operation at full load plus 10%. Due to plant configuration, the proposed EDG day tank TS minimum contained volume of 250 gallons does not provide a 10%
margin.
However, the proposed TS does meet the intent of the Westinghouse Standard TS of providing an hour of EDG operation at full load, plus allowance for unusable fuel oil and some additional margin.
The licensee will set the day tank low-level alarm (including instrument inaccuracy and measurement uncertainty) above the TS minimum contained volume.
Increasing the EDG day tank TS minimum contained volume provides additional conservatism to assure the EDG fuel oil contained in the day tank is sufficient to provide adequate time for an operator to take corrective action to restore the fuel oil supply to the affected day tank in the unlikely event of a failure of tho fuel oil transfer system.
Based on its review, the staff concludes that, with the diesel fuel oil storage and transfer system configuration and operation at DCPP, no single failure of the system will render the fuel oil transfer system inoperable.
Therefore, the staff finds the proposed increase in the minimum required contained EDG day tank volume acceptable.
Since installation of the sixth EDG was performed during the Unit 2 fifth refueling outage, TS references to a five diesel configuration and a common (swing) diesel are outdated and the licensee is proposing that they be removed.
The proposed removal of references to a five diesel configuration in TS 3/4.8.1 and TS 3/4.7.11 is an administrative change that reflects the current plant configuration at DCPP and, therefore, is acceptable.
Due to an administrative oversight, the licensee incorrectly cited TS 3.8.1.1.a in a footnote added to TS 3.8.1.2 as part of License Amendment 74 and 73.
The footnote was intended to reference TS 3.8.1.2.a.
This is an administrative change correcting an error and, therefore, is acceptable.
The additional information in the TS Bases clarifies PG&E's commitments with regard to fuel oil quality requirements, and expands the scope of the
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information contained within the TS Bases, consistent with the intent of NUREG-1431.
In addition, a typographical error is being corrected on TS Bases page B 3/4 3-la.
The word "available" is replaced with " unavailable".
The proposed TS and associated Bases changes for the day tank fuel oil storage requirement and fuel oil quality requirements are TS enhancements.
Based on the above, the staff finds the proposed changes acceptable.
4.0 STATE CONSULTATION
In accordance with the Commission's regulations, the California State official was notified of the proposed issuance of the amendments.
The State official had no comments.
5.0 ENVIRONMENTAL CONSIDERATION
These amendments change a requirement with respect to the installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20 and change surveillance requirements.
The NRC staff has determined that the amendments involve 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 Commission has previously issued a proposed finding that the amendments involve no significant hazards considera-tion, and there has been no public comment on such finding (59 FR 7694).
Accordingly, the amendments meet 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 tne amendments.
6.0 CONCl9SION The Commission 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 endangered by operation in the proposed manner, (2) such activities will be conducted in compliance with the Commission'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. Peterson Date:
August 23, 1994
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