ML19256G245

Commits to Operate Facility in Accordance W/Interim Position Provided in NUREG-0578 Re Containment Purging & Venting During Normal Operation.Schedule for Required Mods Will Be Submitted Approx 800101

ML19256G245
Person / Time
Site:	Cooper
Issue date:	12/18/1979
From:	Pilant J NEBRASKA PUBLIC POWER DISTRICT
To:	Ippolito T Office of Nuclear Reactor Regulation
References
RTR-NUREG-0578, RTR-NUREG-578 NUDOCS 7912280542
Download: ML19256G245 (3)

Text

,g T GENERAL OFFICE g Ne ras a Pu ic ower D str.ic t P. o. Box 499, COLUMBUS. NEBR ASKA 68601 TETE ~o~E i.On s.4.s.

December 18, 1979 Director, Nuclear Reactor Regulation Attention: Mr. Thomas A. Ippolito, Chief Operating Reactors Branch No. 3 Division of Operating Reactors U.S. Nuclear Regulatory Commission Washington, DC 20555

Subject:

Containment Purge and Vent Valve ')perability Cooper Nuclear Station NRC Docket No. 50-298, DPR-46

Reference:

1) Letter from T. A. Ippolito (NRC) to J. M. Pilant (NPPD)

Dated October 22, 1979, " Containment Purging and Venting During Normal Operation"

2) Letter from J. M. Pilant (NPPD) to D. G. Eisenhut (NRC)

Dated October 26, 1979, " Containment Purge and Vent Valve Operability Testing"

Dear Mr. Ippolito:

Reference 1 requested Nebraska Public Power District to commit to operate Cooper Nuclear Station in conformance with an interim position provided and to verify operability of the purge and vent valves on an expedited basis. The following are the Staff's interim positions and NPPD's commitments which meet the conditions listed:

1. Wheneve,1 the coottainmatt httegrity is requited, empita. sis sitoald be placed on ope <1ating tJ1e containment in a passive made as mucIt as passibte and an timLtu19 att pwtghtg and vatting times to as low as acitievable. To justify vasting or pwtging, titere mas.t be an establisited need to improve working conditions to petform a safety related satveillance or safety tela.ted maLottenance procedwte.

(Examples of cnproved working conditions would include deinertb1g, reduebig temperature, Itunidity, and a.itborne activity suf ficiattly to pernLt efficiatt performance or to significantly reduce occu-pationa.l radiation exposwtes) .

Resoonse Containment purge valve operation at Cooper Nuclear Station will continue to be limited to the conditions listed above which are necessary for operation of the station. O3V s

//o 1653 271 , gg g

Thomas A. Ippolito December 18, 1979 Page 2 2a. Ma.isttain de corttainment putge and vent isolation valves closed tdtenever de reactor is not 41 he cold sliatdown or .tefueling made untti sucit time as you can sitow dat all isola,twn valves grea,ter uan 3" nombia.l diameter used for containmatt purge and venting operations are operable under tite most sevete design basis accidott flow conditwn loading and can close witltin de time limit stated h1 your Tecitnical Specificatwns, design esiteria or openatb1g procedures. Tite operabitcty of bu.tterfly vaives may, on an intesim basis, be demonstta.ted by limiting tite value to be no more titan 300 to 500 open (900 being full open) .

Tite maximum open,ing sitall be decennined 41 consulta, tion witit tite value suppliet. Tite valve opoting must be sucit 6ta.t de etitica.C valve parts will not be damaged by DBA-LOCA loads and dat tite value will tend to close witen de fluid dynamic forces are intto-duced.

Response

Reference 2 submitted a proposed test procedure prepared by Allis Chalmers Corporation which verifies containment purge valve oper-ability for Cooper Nuclear Station. The testing has been completed and the air operated purge valves (237AV, 238AV, 245AV, and 246AV) have been verified to close within the time limit stated in the Technical Specifications under DBA-LOCA conditions. The analysis concluded that the motor operated purge valves (230MV, 231MV, 232MV and 233MV) be limited to 60 degrees open due to the limiting factor of motor operator torque capacity.

Commencing 45 days from the date of this letter, the maximum opening of these valves shall be limited to 60 degrees when the plant is not in the cold shutdown or refueling mode, until such time as the oper-ator limiting condition is rectified.

2b. Ma,bttain de conta.inment pu,tge and vatt isolation valves closed tdtatever de reactor is not ht de cold situ,tdown or refuelbig made until sucit time as you can sItow Btat modificatans, as necessaty, Itave been made to segrega,te ne contabtmott vattclation isolation signals to ensure ua,t, as a nutimum, at least one of tite automatic safety 41]ection actuation signals is uninitibited and operable to initiate va.tve closure witen any otiter isolatwn . signal may be blocked, reset, or overtiddat.

Response

As discussed with the Staff in a meeting September 12, 1979, and in subsequent telephone conversations, containment isolation signals to all purge and vent isolation valves remain segregated, unin-hibited and operable to initiate valve closure with the exception that the signal to valves 230MV and 231MV can be overridden with key locked switches. Keys for these switches are under the direct control of the shift supervisor and are governed by plant procedures.

This override function is necessary to permit post-accident venting 1653 272

Thomas A. Ippolito December 18, 1979 Page 3 via the ACAD and SBGT systems. These overrides will only be used for post-accident venting after the ACAD system has been approved by the NRC. Normal purging operations do not employ any override features. No modifications to the containment ventilation isola-tion signals are considered necessary.

Two additional concerns relating to the containment ventilation isolation valves were expressed by the Staff in a telecon November 21, 1979. The response to these concerns is as follows:

1. Desetibe teltetltet die uduttion monitor 17-452ASB titat ptoduces an aatomatic corttautmatt isolatron is qualified safety grade (Class 1E).

Response

The radiation monitor used for the reactor building isolation is a General Electric type 129B2802G12 monitor. This monitor is qualified safety grade (Class lE).

2. Aftet an .utitutu1g signal Iza.s caused automatic containment venti-Lation isolation and tite valves Itave closed, if tite initiating signal ttip is overridden or .ieset, discass icitet!tet tite venttlatton valves automatically re-opat if not prevotted.

Response

The isolation logic cannot be reset until the initiation signal has cleared. When the isolation logic is reset the motor operated containment ventilation valves will remain in the closed position until opened by the operator. Upon isolation logic reset the air operated valves will move to the position selected by the control switch. The control switch is an open-close two position switch.

This feature of the air operated valves will be modified as required by NUF.EG 0578 Lessons Learned position 2.1.4 " Diverse Containment Isolation". The schedule for modification will be submitted approx-imately January 1, 1980.

Should you have any questions, or require additional information, please contact me.

Sincerely, b

a . Pilant Director of Licensing and Quality Assurance JDW/cmk 1653 273 ,