ML19254F775
| ML19254F775 | |
| Person / Time | |
|---|---|
| Site: | Big Rock Point File:Consumers Energy icon.png |
| Issue date: | 10/23/1979 |
| From: | Ziemann D Office of Nuclear Reactor Regulation |
| To: | Bixel D CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| References | |
| NUDOCS 7911190005 | |
| Download: ML19254F775 (5) | |
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UNITED STATES E" c '[ }
NUCLEAR REGULATORY COMMISSION 3
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WASHINGTON, D. C. 20555
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October 23, 1979 Docket No. 50-155 Mr. David Bixel Nuclear Licensing Aaministrator Consumers Power Coupany 212 West Michigan -Avenue Jackson, Micnigan. 49201
Dear Mr. Sixel:
RE: Containuent Purging and Venting During Normal Operation dy letter dated Novencer 29, 1978, the Commission (NRC) requested all licensees of operating reactors to respuna to generic concerns about containuent purgin9 or venting during nonaal plant operation. The generic concerns were twofold:
(1) Events haa occurred wnere licensees overrode or bypassed the safety actuation isolation signals to the containment isolation valves.
Tnese events were aetenained to be abnonaal occurrences and reported to Congress in January 1979.
(2) Recent licensing reviews have requirea tests or analyses to show that containinent pur3e or vent valves would shut without degrading con-tainuent integrity curing the dynallic loads of a design basis loss of coolant accident (DBA-LOCA).
The iiRC position of the hovenber 1978 letter requested that licensees take the following positive actions pending coupletion of the NRC review:
(1) prohibit the override or bypass of any safety actuation signal which woula affect another safety actuation signal the NRC Office of Inspection and Enforceisent would verify that adiiiinistrative controls prevent improper manual defeat of safety actuation signal 5, and (2) cease purging (or venting) of containment or limit purging (or venting) to an absolute miniuuu, not to exceed 90 hours0.00104 days <br />0.025 hours <br />1.488095e-4 weeks <br />3.4245e-5 months <br /> per year. Licensees were requested to deuonstrate (by test or Dy test and analysis) that containment isolation valves woule shut under postulatea 06A-LOCA condition. The NRC positions were amplified oy citation (and an attached copy) of our Standard Review Plan (SRP) 6.2.4 Revision 1 ana the associated Branch Technical Position CSB 6-4, which have effectively classed the purge and vent valves as
" active" invoking the operability assurance program of SRP 3.9.3.
The NRC staff nas uade site visits to several facilities, nas cet with licensees at Betnesaa, harylana, ana has held telecon conferences witn many otner licensees and met with some valve manufacturers. During these aiscussions, the NRC staff has stressec that positive actions must be taken as noted above to assure that containuent integrity would ce naintained in the event of a DBA-LOCA.
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Mr. David Bixel 7 2-October 23, 1979 As a result of these actions, we have learned from several licensees that at least three valve vendors have reported thM. their valves may not close against the ascending differential pressure and the resulting dynamic loading of the design basis LOCA. All identified licensees who are affected have proposed to maintain the valves in the closed position or to restrict the angular opening of the valves whenever primary containment integrity is required until a re-evaluation is provided which shows satisfactory valve perfomance under the DBA-LOCA condition.
Recently, a report 'under 10 CFR Part 21 was received by the NRC from the manufacturer of butterfly valves which are installed in the primary containment at the Three Mile Island Unit 2 Nuclear Station. These butterfly valves are used for purge and exhaust purposes and are required to operate during accident conditions. The report discusses the use of an unqualified solencia valve for a safety-related valve function which requires operation under accident conditions. The solenoid valve is used to pilot control the pneumatic valve actuators which are installed on the containment ventilation butterfly valves at this facility.
Your re-evaluation of valve performance for conoitions noted in the previous paragraph must consider the concerns identified in IE Bulletin 79-01A.
as the NRC review progresses, licensees which might have electrical override circuitry probleus are Deing advised not to use the override and to take coupensatory interiu ueasures to minimize the problem.
In light of the information gained curing our reviews of your submittals dated December 29, 1978 anc Septei.ber 11, 1979, and the information cited above, we believe an interim coumitment frou you is required at this time.
This is the case, even though you may have proposed Technical Specification changes or other long or short-term measures, which we are reviewing. For your use, we have provided as an attachment an interim NRC staff position.
Ie addition, our recently aeveloped " Guidelines for Demonstration of Oparability of Pur3e and Vent Valves" were provided by separate letter to iicensees of eacn operating reactor. This letter in no way relaxes any existing licensing requireuents for your facility.
Because of the potential adve'se effects on the public health and safety wnich could result from the postulated, DBA-LUCA while operating with open purge or vent valves, we believe your proupt response to this letter is requirec.
In accordance with 10 CFR 50.54(f), you are requested 1353 116
Mr. David Bixel October 23, 1979 to infom us in writing within 45 days of receipt of this letter of your coalituent to operate in conformance with the enclosed interim position and to provide us with infonnation which demonstrates that you have initiated the purge and vent valve operability verification on an expedited basis. The information provided in your response will enable us to determine whether or not your license to operate Big Rock Point Plant should be modified, suspended, or revoked.
Sinc erely, s, - [ 2 u.
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Dennis L. Ziemann/ Chief Operating Reactors Branch #2 Division of Operating Reactors
Enclosure:
Interim Position for Containment Purge ano Vent Valve Operation cc: w/ enclosure See next page 1353 117 e
Mr. David Bixel 4-October 23, 1979 1
cc w/ enclosure:
Mr. Paul A. Perry, Sec retary Cansuners Power Company 212 West Michigan Avenue Jackson, Michigan 49201 Judd 1. Bacon, Esquire Consumers Power Conpany 212 West Michigan Avenue Jackson, Michigan 49201 Hunton & Willians George C. Freeman, Jr., Esquire P. O. Box 1535 Richnond, Virginia 23212 Peter W. Steketee, Esquire 505 Peoples Building Grand Rapids, Michigan 49503 Sheldon, Harnon, Roisman and Weiss 1725 I Street, N. W.
Suite 506 Washington, D. C.
20006
'tr. John ^ ;e il l, I I Route 2, Fox 44 Maple City, ichigan 49664 Charlevoix Public Library 107 Clinton Street Charlevoix, Michigan 49720 1353 118
INTERIM POSITION,FOR CONTAINMENT PURGE AND VENT VALVE OPERATION PENDING RESOLUTION OF ISOLATION VALVE OPERABILITY Once the conditions listea below are met, restrictions on use of the containment purge ana vent system isolation valves will be revised based on our review of your responses to the November 1978 letter justifying your proposed operational mode. The revised restrictions can be established separately for each system.
1.
Whenever the containment integrity is required, emphasis should be placed on operating the containraent in a passive mode as much as possible and on limiting all purging and venting times to as low as achievable.
To justify venting or purging, there must be an established need to improve working conditions to perform a safety related surveillance or safety related maintenance procedure.
(Examples of improved working conditions would include deinerting, reducing temperature *, humidity *,
and airborne activity sufficiently to permit efficient perfomance or to significantly reduce occupational radiation exposures), and 2.
haintain the containment purge and vent isolation valves closed whenever the reactor is not in the cold shutdown or refueling mode until such time as you can show that:
a.
All isolation valves greater than 3" nominal diameter used for containment purge and venting operations are operable under the most severe design basis accident flow condition loading and can close within the time limit stated in your Technical Specifications, design criteria or operating procedures. The operability of butter-fly valves may, on an interim basis, be demonstrated by limiting the valve to be no more than 30 to 50* open (90 being full open). The maxiuui., opening shall be determined in consultation with the valve suppl ier. The valve opening must be such that the critical valva parts will not be damaged by DBA-LOCA loads and that the valve will tend to close when the fluid dynamic forces are introduced, and b.
Hoaifications, as necessary, have been made to segregate the containment ventilation isolation signals to ensure that, as a minimum, at least one of the automatic safety injection actuation signals is uninhibited and operaole to initiate valve closure when any other isolation signal may be blocked, reset, or overridden.
- unly where temperature and humidity controls are not in the present design.
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