ML19254F780
| ML19254F780 | |
| Person / Time | |
|---|---|
| Site: | La Crosse File:Dairyland Power Cooperative icon.png |
| Issue date: | 10/23/1979 |
| From: | Ziemann D Office of Nuclear Reactor Regulation |
| To: | Linder F DAIRYLAND POWER COOPERATIVE |
| References | |
| NUDOCS 7911190013 | |
| Download: ML19254F780 (5) | |
Text
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o UNITED STATES NUCLEAR REGULATORY COMMISSION g
C WASHINGTON, D. C. 20555 k*
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October 23, 1979 Docket No. 50-409 Mr. Frank inder General Manager Dairylona Power Cooperative 2615 East Avenue South La Crosse, Wisconsin 54601
Dear Mr. Linder:
RE: Containment Purging and Venting During Normal Operation By letter dated November 29, 1978, the Commission (NRC) requested all licensees of operating reactors to respond to generic concerns about containment purging or venting during normal plant operation. The generic concerns were twofold:
(1) Events had occurred where licensees overrode or bypassed the safety actuotion isolation signals to the containment isolation valves.
These events were deteruineo to be abnormal occurrences and reported to Congress in January 1979.
(2) Recent 1icensing reviews have required tests or analyses to show that containtaent pur9e or vent valves would shut without degrading con-tainment integrity curing the dynamic loads of a design basis loss of coolant acciaent (DBA-LUCA).
The NRC position of the November 1978 letter requested that licensees take the following positive actions pending completion of the NRC review:
(1) pronibit the override or bypass of any safety actuation signal which would affect another safety actuation signal; the NRC Office of Inspection and Enforcement would verify that administrative controls prevent improper manual defeat of safety actuation signals, and (2) cease purging (or venting) of containment or limit purging (or venting) to an absolute minimum, 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 demonstrate (by test or by test and analysis) that containment isolation valves would shut under postulated DBA-LOCA condition. The NRC positions were amplified by citation (and an attached copy) of our Standard Review Plan (SRP) 6.2.4 Revision 1 and the associated Branch Technical Position CSB 6-4, which have effectively classed the purge and vent valves as
" active" invoking the operability assurance prograa of SRP 3.9.3.
The NRC staff has made site visits to several facilities, has met with licensees at Bethesda, Maryland, and has held tel _on conferences with many other licensees and met with some valve manufacturers. During these discussions, the hRC staff has stressed that positive actions must be taken as noted above to assure that containment integrity would be maintained in the event of a DBA-LOCA.
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Mr. Frank Linder October 23, 1979 i
As a result of these actions, we have learned from several licensees that at least three valve vendors have reported that their valves may not close against the ascending differential pressure and the resulting dynaaic 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 rtile Island Unit 2 Nuclear Station. These butterfly valves are useo for purge and exhaust purposes and are required to operate during accident conditions. The report discusses the use of an unqualified solenoid 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 conuitions noted in the previous paragraph must consider the concerns identified in IE Bulletin 79-OlA.
As the NRC review progresses, licensees which might have electrical overriae circuitry problems are being advised not to use the override and to take compensatory interim measures to minimize the problem.
In light of the infomation gained during our reviews of your submittals ddtea February 1,1979, July 5,1979 and meeting in Bethesda, Maryland, on August 22, 1979, and the infomation cited above, we believe an interim counitment fron, you is required at this time. This is the case, even though you may have proposed Technical Specification changes or other lons or snort-tem measures, which we are reviewing.
For your use, we have provided as an attachment an interiu NRC staff position.
In addition, our recently developed " Guidelines for Demonstration of Operability of Pur e and Vent Valves" were provided by separate letter s
to licensees of each operating reactor. This letter in no way relaxes any existing licensing requirements for your facility.
Because of the potential adverse eff~ects on the puolic health and safety whicn coulo result from the postulated, DBA-LOCA while operating with open purge or vent valves, we believe your prompt response to this letter is requirea.
In accordance with 10 CFR 50.54(f), you are requested 1353 137
Mr. Frank Linder October 23, 1979 to inform us in writing within 45 days of receipt of this letter of your commitment to operate in confomance with the enclosed interim position and to provide us with infomation which demonstrates that you have initiated the purge and vent valve operability verification on an expecited basis. The infonnation provided in your response will enable us to determine whether or not your license to operate La Crosse Boiling Water Reactor should be modified, suspended, or revoked.
Sincerely,
') ].m 9.
K'w M w Dennis L. Ziemann Chief e
Operating Reactors Branch #2 Division of Operating Reactors
Enclosure:
Interim Position for Containment Purge and Vent Valve Operation cc: w/ enclosure See next page 1553 138
Mr. Frank Linder 4-October 23, 1979 cc w/ enclosure:
E Fritz Schubert, Esquire Staff Attorney Dairyland Power Cooperative 2615 East Avenue South La Crosse, Wisconsin 54601
- 0. S. Heistand, Jr., Esquire Morgan, Lewis & Bockius 1800 M Street, N. W.
Washington, D. C.
20036 Mr. R. E. Shinshak La Crosse Boiling Water Reactor Dairyland Power Cooperative P. O. Box 135 Genoa, Wisconsin 54632 Coulee Region Energy Coalition ATTN: George R. Nygaard P. 0. Box 1583 La Crosse, Wisconsin 54601 Charles Bechhoefer, Esq., Chairman At.omic Safety and Licensing Board U. S. Nuclear Regulatory Commission Washington, D. C.
20555 Dr. George C. Anderson Department of Oceanography University of Washington Seattle, Washington 98195 Mr. Ralph S. Decker Route 4, Box 1900 l} l3g Cambridge, Maryland 21613 La Crosse Public Library 800 Main Street La Crosse, Wisconsin 54601
INTERIM POSITION 'FOR CONTAINMENT PURGE AND VENT VALVE OPERATION PENDING RESOLUTION OF ISOLATION VALVE OPERABILITY Once the conaitions listed below are met, restrictions on use of the containment purge and 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 containment 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 peruit efficient performance or to significantly reduce occupational radiation exposures), and 2. Maintain 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: All isolation valves greater tnan 3" nominal diameter used for a. containment purge and venting operations are operable under the uost 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 maximum opening shall be determined in consultation with the valve supplier. The valve opening must be such that the critical valve parts will not be damaged oy DBA-LOCA loads and that the valve will tend to close when the fluid dynamic forces are introduced, and b. Modifications, 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 operable to initiate valve closure when any other isolation signal may be blocked, reset, or overridden.
- Only where temperature and humidity controls are not in the present design.
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