ML17339A277
| ML17339A277 | |
| Person / Time | |
|---|---|
| Site: | Turkey Point  |
| Issue date: | 10/23/1979 |
| From: | Schwencer A Office of Nuclear Reactor Regulation |
| To: | Robert E. Uhrig FLORIDA POWER & LIGHT CO. |
| References | |
| NUDOCS 7911190017 | |
| Download: ML17339A277 (8) | |
Text
OCTOBER 2 3 1979 Docket Hos. 50-250 and b =2 Dr. Robert E. Uhrfg, Vice President Advanced Systems and Technology Florida Power and Light Company Post Office, Box 529100 t1fami, Florida 33152 MIllUI'MftIIIjDI,')(pFII) gipg
Dear Dr. Uhrfg:
RE:
Containment Purging and Venting During Normal Operation By letter dated November 28, 1978, the Commission (NRC) requested all licensees of operating reactors to respond to generic concerns about'ontainment purging or venting during normal plant operation.
The generic concerns were twofold:
(1)
Events had occurred where licensees'overrode or bypassed the safety actuation isolation signals to the containment isolation valves.
These events were"determined to be abnormal occurrences and reported to Congress in January 1979.
(2)
Recent licensing reviews have required tests or analyses to show that containment purge or vent valves would shut without.degradfng con-tainment integrity during the dynamic loads of a design basis loss of coolant accident (DBA-LOCA).
The NRC position of the November 1978 letter requested that licensees take the following positive actions pending completion of the NPC review:
(1) prohibit the override or bypass of any safety actuatfon 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) 6e2.4 Revision 1
and the associated Branch Technical Posftion
=-
CSB 6-4, which have effectively classed the purge and vent valves as "active" invoking the operabjlfty assurance program of SRP 3.9;3.
S The NRC staff has made site visits to several facilities, has met with licensees, at Bethesda, flaryland, and has held telecon 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 contaInnent IntegrIty uould be >aaintaIned Q) Q in the event of a DBA-LOCA.
V9lXX90 OFFICE $ >. ~
SURNAME OATE $.
NRC FORM 318 (9 76) NRCM 0240 0 U.S. GOVERNMENT PRINTING OFFICE: 1979 289 369
Pr. Robert E. Uhrfg 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
'ynamic 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 fs required until a re-evaluation fs provided which shows satisfactory valve performance under the DBA<<LOCA condition.
- Recently, a report under 10 CFR Part gl was received by the NRC from the manufacturer of butterfly valves which are installed fn the primary containment at the Three Nile Island Unit 2 Nuclear Statfon.
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
'olenoid 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 fnstalled on the containment ventilation butterfly valves at this facility.
Your re-evaluation of
, valve performance for conditions noted fn the'revious paragraph must consider the concdrris identified fn IE Bulletin 79-01A.
As the tlRC revfe~>> progresses, licensees which might have electrical override circuitry problems are befng advised not to use the overifde and to take compensatory interim measures to mfnfmfze the problem.
In light of the information gained during our reviews of your'ubmittal s dated January 6, February 1, and June 8, 1979 and the information cited
- above, we believe an inter'fm commitment from you fs required at this time.
This fs the case, even though you may have proposed Technical Specification changes or other long or short-term measures,
<<hfch we are reviewing.
For your use, we have provided as an attachment an interim NRC staff position.
In addition, our recently developed "Guidelines for Demonstration of Operability of Purge and Vent Valves" were provided by separate letter to licensees of each operating reactor.
This letter in na way relaxes any existing licensing requirements for your facility.
Because of the potential adverse effects on the public health and safety which could result from the postulated, DBA-LOCA <<hile operating with open purge or vent valves, we believe your prompt response to this letter is required.
In accordance with 10 CFR 50,54(f), you are requested OFFICE)...
SURNAME DATE,$..
NRC FORM 318 I9.76) NRCM 0240
- I.I.S, GOVERNMENT PRINTING OFFICE: 1979.289.369
Or. Robert E. Uhrig 3
1 to inform us in>>riting>>ithin 45 days of'eceipt of this letter of your commitment to operate in conformance>>ith the enclosed interim position and to provide us with information which demonstrates that you have initiated the purge and vent valve operability verification on an expedited basis.
The inforttation provided in your response>>ill enable us to determine>>hether or not your license to operate Turkey Point Plant Unit Nos.
3 and 4 should be modified, suspended,.
or revoked.
Sincerely, Original Signed By A. Sch>>encer, Chief Operating Reactors Branch Pl Division of Operating Reactors Encl osur e:
Interim Position for Containment Purge and Vent Valve Operation cc:
>>/enclosure See next page
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OFFICE)
SURNAME DATE$
DOR:OR l~
MGrotenhuis 10/ I7/79:jb DOR:
ASch e
er 10/
79 10/~9 NRC FORM 318 (9.76) NRCM 0240
- 'll.S GOVERNMEIVTPRINTING OFFICE: 1979 289 369
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++*++Docket Nos.
50-250 and 50-251 i ~
UNITEDSTATES NUCLEAR REGULATORY COMMISSION WASHINGTON, O. C. 20555 QQTOBc?
a l979 Dr. Robert E. Uhrig, Vice President Advanced Systems and Technology Florida Power and Light Company Post Office Box 529100 Miami, Florida 33152
Dear Dr. Uhrig:
RE:
Containment Purging and Venting During Normal Operation By letter dated November 28, 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 actuation isolation signals to the containraent isolation valves.
These events were determined to be abnormal occurrences and reported to Congress in January 1979.
(2)
Recent licensing reviews have required tests or analyses to show that containment purge or vent valves would shut without degrading con-tainIIent integrity during the dynamic loads of a design basis loss of cool ant accident (DBA-LOCA).
The NRC position of the November 1978 letter requested that licensees take the following positive actions pending completion of the NPC review:
(1) prohibit 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 IIIinimuII, 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 iso'iation 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 assur'ance program 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 telecon conferences with many other licensees and met with some valve manufacturers.
During these discussions, the NRC staff has stressed that positive actions must be taken as noted above to assure that containrIent integrity would be maintained in the event of a DBA-LOCA.
Dr. Robert E. Uhrig
> oigR q
". cqvg 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 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 performance 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 i'h le 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 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 conditions 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 problems are being advised not to use the override and to take compensatory interim measures to minimize the problem.
I In light of the information gained during our reviews of your submittals dated January 5, February 1, and June 8, 1979 and the information cited
- above, we believe an interim commitment from you is required at this time.
This is the case, even though you may have proposed Technical Specification charges 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.
In addition, our recently developed "Guidelines for Demonstration of Operability of Purge and Vent Valves" were provided by separate letter to licensees of each operating reactor.
This letter in no way relaxes any existing licensing requireoents for your facility.
Because of the potential adverse effects on the public health and safety which could resu'it from the postulated, DBA-LOCA while operating with open purge or vent valves, we believe your prompt response to this letter is required.
In accordance with 10 CFR 50. 54(f), you are requested
Dr. Robert E. Uhrig OCTOBER g
- tyg to inform us in writing within 45 days of receipt of this letter of your commitment to operate in conformance with the enclosed interim position and to provide us with information 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 Turkey Point Plant Unit Nos.
3 and 4 should be modified, suspended, or revoked.
Sincerely, r
ggg@zccCiz~
A. ScBwencer, Chief Operating Reactors Branch Pl Division of Operating Reactors
Enclosure:
Interim Position for Containment Purge and Vent Valve Operation cc:
w/enclosure See next page
Robert E. Uhrig Florida Power and Light Company
- 4 OCTOBEk '9~9 cc:
Mr. Robert Lowenstein, Esquire Lowenstein,
- Newman, Reis and Axelrad
---1025 Connecticut
- Avenue, N.M.
Suite 1214 Mashington, D. C.
20036 Environmental and Urban Affairs Library Florida International University
'iami, Florida 33199 Mr. Norman A. Coll, Esquire
- Steel, Hector and Davis 1400 Southeast First National Bank Building
- Miami, F 1 or i da 33131 Mr. Henry Yaeger, Plant Manager Turkey Point Plant Florida Power and Light Company P. 0.
Box 013100 Miami, Florida 33101 Mr. Jack Shreve Office of the Public Counsel Room 4, Holland Building Tallahassee, Floriaa 32304
INTER It) POSITION FOR CONTAINYiENT PURGE AND VENT VALVE OPERATION PEHDING RESOLUTIOH OF.ISOLATION
.'E OPERABILITY Once the conditions 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 estab lished 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 terperature*,
humidity*,
and airborne activity sufficiently to permit efficient performance 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'o 50'pen (90'eing 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 by DBA-LOCA loads and that the valve will tend to close when the fluid dynamic forces are introduced, and b.
t4odifications, 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 o:her isolation signal may be blocked, reset, or overridden.
" On y where temperature and humidity controls are not ir:
".e present design.