ML20209E249

Application for Amend to License NPF-43,revising Tech Spec 3/4 6.1.7 to Change Drywell Average Air Temp Limit from 135 F to 145 F.Fee Paid

ML20209E249
Person / Time
Site:	Fermi
Issue date:	04/27/1987
From:	Agosti F DETROIT EDISON CO.
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
Shared Package
ML20209E253	List: ML20209E249 ML20209E255
References
TAC-65174, VP-NO-87-0035, VP-NO-87-35, NUDOCS 8704300008
Download: ML20209E249 (9)

Text

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e

• Frank E. Agostl Nucle r tions

'N"4 Detroit r.-

rt M ch Nuclear (313) 586-4150 Operations

-April 27, 1987 VP-NO-87-0035 l

U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D. C. 20555 l

l.

Reference:

Fermi 2 l NRC Docket No. 50-341 NRC License No. NPF-43

Subject:

Proposed Technical Specification Change-Drywell Average Air Temperature (3/4 6.1.7)

Pursuant to 10CFR50.90. Detroit Edison Company hereby proposes to amend Operating License NPF-43 for the Fermi 2 plant by iacorporating the enclosed change into the Plant Technical Specification 3/4.6.1.7 Drywell Average Air Temperature. This proposed change will change the drywell average air temperature limit from 135 F to 145 F.

Detroit Edison has evaluated the proposed Technical Specification change against the criteria of 10CFR50.59 and 10CFR50.92 and determined that no unreviewed safety question or significant hazards consideration is involved.

The Fermi 2 Onsite Review Organization has approved and the Nuclear Safety Review Group has reviewed this proposed Technical Specification and concurs with the enclosed determinations.

Pursuant to 10CFR170.12(c), enclosed with this amendment request is a check for one hundred fifty dollars ($150.00).

B704300008 870427 W;\

PDR ADOCK 05000341 I )

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. . USNRC April 27, 1987 VP-NO-87-0035' Page 2 In accordance with 10CFR50.91. Detroit Edison has provided a copy of this letter to the State of Michigan.

If you have any questions, please contact Mr. Steven Frost at (313) 586-4210.

Sincerely.

2 .' 8 F. E. Agosti Vice President Nuclear Operatiotis Enclosure cc: Mr. A. B. Davis Mr. E. Greenman Mr. W. G. Rogers Mr. J. J. Stefano Supervisor. Advanced Planning & Review Section Michigan Public Service Commission

, USNRC April 27, 1987

. VP-NO-87-0035 Page 3 i'

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I, FRANK E. AGOSTI do hereby affirm that the foregoing statements are based on facts and circumstances which are true and accurate to the best of my knowledge and i belief.

i bf FRANK E. AGOSTI i Vice President Nuclear Operations On this 7 day of N 1987.

before me personally appeared Frank E. Agosti, being

first duly sworn and says that he executed the foregoing as his free act and deed.

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Notary Public

.. .,a ua N.,t ry Fubisc. Washtenaw C0unty, MI j My Cornmission Expires Dec.& W v Ww

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, , BANGROUIW/ DISCUSSION

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The existing Fermi 2 Technical Specification (3/4.6.1.7g requires that the drywell average air temperature not exceed 135 F. The proposed change would increase this drywell average air temperature limit to 145 F to ensure continuous operation of Fermi 2 during the summer months without any derating of the plant.

Although Fermi 2 has currently not experienced any derating of the plant because of drywell average air temperature, a re-analysis of the drywell heat loads, with all systems operable, indicates that the existing drywell average air temperature limit of 135 F could be approached or exceeded during the summer months. This problem has been experienced by other operating Boiling Water Reactors (BWRs) as several plants have proposed and been granted relief to increase the drywell average air temperature limit.

In view of the re-analysis of the drywell heat load and calculating the potential of approaching or exceeding the existing 135 F limit, Detroit Edison directed General Electric and Sargent & Lundy to evaluate the impact of a 10 F increase (to 145 F) in drywell average air temperature to determine the potential effect on plant safety and performance. A summary of the results are as follows:

A. LOCA Analysis The limitations on drywell average air temperature ensures that the containment peak air temperature does not exceed the design temperature of 340 F during Loss of Coolant Accident (LOCA) conditions and is consistent with the safety analysis. The potential concerns associated with higher than normal drywell temperature are due to its direct effect on the containment response and dynamic loads during a LOCA and on the Safety Relief Valve discharge line (SRVDL) reflood height following an SRV actuation. The potential for indirect effects on the response of the Reactor Pressure Vessel (RPV) water level during a LOCA or abnormal transient due to a temperature induced water level instrument error is very small and not a concern. Tbc water level instrumentation is routed in a manner which produces approximately equal vertical water leg lengths within the drywell for both the process and reference sensing lines. Since the drywell temperature affects both lines equally, the water level reading, which is measured by the differential pressure between the lines, is not influenced by the drywell temperature.

In evaluating the effect of higher initial drywell temperature the design basis LOCA was analyzed. The design basis LOCA results in the most severe drywell pressurization rate and peak pressure loading.

Containment pressure and temperature response results for a higher initial drywell temperature (145 F) were compared with those for the current (135 F)

, , Enclorure to VP-NO-87-0035 Page 2 initial drywell temperature assumption. As expected, the results indicate a less severe response with the higher initial temperature. The results, preser.ted below, show lower peak pressures and lower drywell pressurization rate for the higher initial drywell temperature, which is expected because of reduced air density at a higher temperature. There was negligible effect on peak temperatures. This comparison demonstrates that existing Mark I Load Definition Report (LDR) loads (based on 135 F) bound the loading at the higher initial drywell temperature.

Initial Drywell Temp. ( F) 135 145 Peak Drywell Pressure, (psia) 62.55 62.43 Peak Wetwell Pressure, (psia) 40.24 39.71 Drywell Pressurization rate, 53.7 52.5 (psi /sec)

In order to evaluate the effect of higher initial drywell temperature on pool swell loads, analyses were performed to determine which plant parameters and pool swell variables would be affected. Since the design basis accident produces the most severe pool swell loads, smaller breaks were not investigated. The results demonstrated that the higher initial drywell temperature would produce lower pool swell loads (both downward and upward) with the effect being a direct result of the reduced pressurization rate.

To quantify the effect of higher drywell temperature on the SRVDL reflood height, model predictions of the reflood height for drywell temperatures of 135 F and 145 F were compared. Results of this comparison showed that the higher drywell temperature has a negligible effect on the SRVDL reflood height.

B. Structural Steel and Concrete The Fermi 2 Design Specification states that the design temperature for drywell structural steel and concrete is 150 F. As such, the increase in drywell ambient temperature to 145 F is within the design basis.

C. Piping, Hangers and Supports Piping systems, inclusive of their supports are designed considering the process fluid temperatures.

Lines with a design specification temperature of greater than 150 F are analyzed at their design temperature and will not be affected by drywell

Enclorura to VP-NO-87-0035 Page 3 ambient temperature of 145 F. Lines with design specification temperatures of less than or equal to 150 F are considered cold and no thermal analysis is required. A drywell ambient temperature of 145 F is below that of the 150 F design specification temperature and will, therefore, not affect the piping system design.

D. Equipment and Components Equipment aging and operability assessments were conducted for equipment and components which would be exposed to the higher drywell average air temperature. The results concluded that all the equfpmentandcomponentswouldremainoperableat 145 F and wocid perform their intended safety function. The only potential would be the accelerated aging of some equipment such as seals, solenoid valves and pressure switches. This would result in the need to replace these components at an earlier date.

Detroit Edison will monitor the equipment and components through an Environmental Qualification Preventative Maintenance Program to ensure the replacement of these items prior to exceeding their qualified life.

Based on these evaluations, it is concluded that the higher drywell average air temperature will not adversely affect the containment response and dynamic loads during a postulated LOCA or on the SRVDL reflood transient. Fermi 2 will continue to be in compliance with General Design Criteria 4 and 10 of 10CFR Part 50, Appendix A. Additionally, the temperature increase will not significantly affect any of the safety analysis previously performed nor affect the ability of any of the equipment to perform its intended safety function.

SIGNIFICANT HAZARDS CONSIDERATION In accordance with 10CFR50.92. Detroit Edison has made a determination that the proposed amendment involves no significant hazards considerations. To make this determination Detroit Edison must establish that operation in accordance with the proposed amendment would not: 1) involve a significant increase in the probability or consequences of an accident previously evaluated, or 2) create the possibility of a new or different kind of accident f rom any accident previously evaluated, or 3) involve a significant reduction in a margin of safety.

1. The proposed change to increase the drywell average air temperature to 145 F does not involve a significant increase in the probability or consequence

Enclo3ura to VP-NO-87-0035 Page 4 of an accident previously evaluated. The change does not involve a physical modification to the plant or a change in operating practices. The change does involve a change in the limiting conditions for operation which has been evaluated against environmental qualification requirements, drywell concrete design requirements, piping, hanger and support requirements, balance of safety related mechanical equipment in the drywell and the bounding safety analysis accident (LOCA). Operation at the proposed higher temperature would potentially impact some equipment by accelerated aging. This would only result in the need to replace some components at an earlier date. Equipment and component operability, however, would not be affected and the intended safety function performance would not be degraded.

Thus, there is no significant increase in the probability or consequences on an accident previously evaluated.

2. The proposed change to increase the drywell average air temperature to 145 F does not create the possibility of a new or different kind of accident from any accident previously evaluated. The increase in drywell average air temperature is within the bounds of the results ectablished in the Final Safety Analysis Report for the design basis LOCA. The change will not impact plant performance and will not provide an opportunity for the plant to enter a condition not previously evaluated.

Thus, the change does not create the possibility of a new or different kind of accident from any accident previously evaluated.

3. The proposed change to increase the drywell average air temperature to 145 F does not involve a significant reduction in a margin of safety. By j increasing the drywell averar,e air temperature for normal operations, there is no significant impact on the dynamic loads or the containment response during a LOCA. The analysis indicates that the peak drywell pressure, peak wetwell pressure and drywell

, pressurization rate actually decreases with the

increase in drywell temperature. The margin of safety l

is maintained with the increase in drywell average air temperature.

Thus, the change does not involve a significant reduction in a margin of safety.

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, , Enclorura to VP-NO-87-0035 Page 5 EINIBOWEENTAL IMPACT Detroit Edison has reviewed the proposed Technical Specification change against the criteria of 10CFR50.22 for environmental considerations. As shown above, the proposed change does not involve a significant hazards consideration, nor increase the types and amounts of effluents that may be released offsite, nor significantly increase individual or cumulative occupational radiation exposures. Based on the foregoing. Detroit Edison concludes that the proposed Technical Specification change meets the criteria given in 10CFR51.22(c) (9) for a categorical exclusion from the requirement for an Environmental Impact Statement.

CONCLUSION Based on the evaluations above: (1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, and (2) such activities will be conducted in compliance with the Commission's regulations and proposed amendments will not be inimical to the common defense and security or to the health and safety of the public. The increase in drywell average air temperature has been previously accepted at Brunswick Unit 2 (July 12,1985), Hatch Unit 2 (July 26, 1979) and Oyster Creek (November 22, 1985).

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