LIC-90-0485, Confirms Interim Resolution of Identified Problem Associated W/Use of Input Variable for PORV Opening Time in Calculation of Low Temp Overpressure Protection Sys Setpoints

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Confirms Interim Resolution of Identified Problem Associated W/Use of Input Variable for PORV Opening Time in Calculation of Low Temp Overpressure Protection Sys Setpoints
ML20058M992
Person / Time
Site: Fort Calhoun Omaha Public Power District icon.png
Issue date: 08/07/1990
From: Gates W
OMAHA PUBLIC POWER DISTRICT
To:
NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LIC-90-0485, LIC-90-485, NUDOCS 9008130153
Download: ML20058M992 (2)


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, Omaha Public Power District 444 South 16th Street Mall Omaha, Nebraska 68102-2247 402/636 2000 August 7, 1990 LIC-90-0485 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Mail Station PI-137 Washington, DC 20555

REFERENCES:

1.. Occket 50 285

2. Licensee Event Report 90 015 dated June 7, 1990 (LIC-90-0471)
3. NRC Generic Letter 90-06, dated June 25, 1990 Gentlemen:

SUBJECT:

Low Temperature Overpressure Protection System Setpoints As requested by the members of the NRC staff on May 10, 1990, this letter serves to confirm Omaha Public Power District's (OPPD) interim resolution of the identified problem associated with the use of an input variable for the Power Ocerated Relief Valve (PORV) opening time in the calculation of Low Tempersture .r Tressure Protection (LTOP) system setpoints. Further discussion of the problem is provided in Reference 2.

As summarized in the May 10, 1990 telephone call with Messrs. A. Bournia, T.

Collins, M. McCook, K. Wickman, J. Sao, P. Harrell, and T. Reis of the NRC and T. Therkildsen, K. Holthaus, and J. Lofshult of OPPD, procedure changes to the

. Fort Calhoun Operating Manual have been implemented which ensure that the existing LTOP setpoints are adequate, assuming PORV opening times (0.8 seconds)

F which bound those measured during the 1990 Refueling Outage (0.32 seconds and 0.36 seconds). The revised operating limits ensure that the current LTOP setpoints are conservative with respect to the Technical Specification Reactor Coolant System (RCS) Pressure - Temperature (P-T) limits.

The revised requirements below are necessary for water solid conditions, and apply to heatups and cooldowns. When the RCS is vented, the requirements below do not apply. The procedure changes specify the following:

(1) The criterion to start a reactor coolant pump is that the steam generator secondary side temperature be less than 30*F above that of the reactor coolant system cold leg (current Technical Specification l',mit is 50'F delta-T) or that a pressurizer steam space of 60% by volume or greater exists.

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.U. S. Nuclear Regulatory Commission LIC-90-0485 Page 2 (2) Whenever the reactor coolant system cold leg temperature is below 325'F (current Technical Specification limit is 320'F), at 1c.ast one High Pressure Safety Injection *HPSI) pump shall be disabled. -

Whenever the reactor coolant system cold leg temperature is below 320'F (current Technical Specification limit is 312*F), at least two HPSI pumps shall be disabled. Whenever the reactor coolant system cold leg temperature is below 290*F (current Technical Specification limit is 271*F), all three HPSI pumps shall be disabled, in the event that no charging pumps are operable, a single HPSI pump may be made operable and utilized for boric acid injection to the core. In this case, HPSI pump flow rate must be restricted-such that the flow rate of three cha.rging pumps is not exceeded and all charging pumps must be disabled.

(3) for cooldowns, when RL temperature is reduced below 300'F, the couldown rate must be maintained at less than or equal to 20'F/hr.

(4) During an RCS cooldown, shutdown cooling must be established before the RCS cold leg temperature is reduced below 250*F.

The administrative controls imposed by items (1) through (4) above are interim, and will be complied with consistent with Nuclear Policy 1.03, "Use of Procedures". Revisions to the Operating Manual require a 10CFR50.59 Safety Evaluation and PRC approval,

, During the telecon noted above OPPD was to submit the related Technical Specification amendment request to the NRC by July 31, 1990. Generic Letter 90 06 (Reference 3), recently issued requires a Technical Specification amendment concerning LTOP. OPPD will combine the above referenced revision with the amendment requested in the Generic Letter. The Generic Letter requires submittal of an amendment request "by the end of the first refueling outage that starts 6 months or later from the date of this letter."

If you should have any questions regarding this matter, please contact me.

Sincerely,

( GL M *)

W. G. Gates Division Mahager Nuclear Operations WGG/sel c: LeBoeuf, Lamb, Leiby & MacRae A. Bournia, NRC Project Manager R. D. Martin, NRC Regional Administrator, Region IV P. H. Harrell, NRC Senior Resident Inspector t