NRC Generic Letter 1988-03
| ML031200470 | |
| Person / Time | |
|---|---|
| Site: | Beaver Valley, Millstone, Calvert Cliffs, Davis Besse, Salem, Oconee, Mcguire, Palisades, Palo Verde, Indian Point, Kewaunee, Catawba, Harris, Wolf Creek, Saint Lucie, Point Beach, Watts Bar, Sequoyah, Byron, Arkansas Nuclear, Three Mile Island, Braidwood, Summer, Prairie Island, Seabrook, Surry, North Anna, Turkey Point, Crystal River, Haddam Neck, Ginna, Diablo Canyon, Callaway, Vogtle, Waterford, Farley, Robinson, South Texas, San Onofre, Cook, Comanche Peak, Yankee Rowe, Maine Yankee, Rancho Seco, Zion, Midland, Bellefonte, Fort Calhoun, McGuire, 05000000, Washington Public Power Supply System, Trojan, Marble Hill |
| Issue date: | 02/17/1988 |
| From: | Miraglia F Office of Nuclear Reactor Regulation |
| To: | |
| References | |
| GSI-093 GL-88-003, NUDOCS 8802180267 | |
| Download: ML031200470 (10) | |
I .
.4 UNITED STATES
NUCLEAR REGULATORY COMMISSION
e WASHINGTON, D. C. 2055 TO ALL LICENSEES, APPLICANTS FOR OPERATING LICENSES, AND HOLDERS OF
CONSTRUCTION PERMITS FOR PRESSURIZED WATER REACTORS
Gentlemen:
SUBJECT: RESOLUTION OF GENERIC SAFETY ISSUE 93, "STEAM BINDING OF
AUXILIARY FEEDWATER PUMPS" (GENERIC LETTER 88-03)
This generic letter is being issued:
(1) to inform you of the staff's resolution of the subject generic safety issue, and
(2) to request that you continue to implement, as a minimum, the monitoring and corrective procedures previously identified for interim resolution of this issue in IE Bulletin 85-01, "Steam Binding of Auxiliary Feedwater Pumps,' dated October 29, 1985.
(A copy of this bulletin is attached.)
pumps The issue concerns the potential disabling of auxiliary feedwater (AFW) past by steam binding that is caused by backleakage of main feedwater (MFW) is the isolation check valves between the AFW and MFW systems. The issue significant because most AFW systems are potentially vulnerable to common mode failure of the redundant AFW pumps as a result of steam binding. This vulnerability is inherent to the piping configurations used, which allow redundant trains of AFW to be cross-connected via common headers on the suction and discharge sides of the pumps.
binding To reduce the probability of AFW pump failure as a consequence of steam if backleakage does occur, IE Bulletin 85-01 requested that certain licensees the and construction permit holders implement procedures both for monitoring AFW piping temperatures for indication of possible backleakage and for restoring the pumps to operable status if steam binding were to occur. The bulletin was not issued to all holders of operating licenses and construction that permits for pressurized water reactors because the staff had determined a number of them had already taken actions that would minimize the occurrence recommended of the AFW pump steam binding problem at their plants. The bulletin recommended a monitoring frequency of once a shift, compared with the previously of frequency of once a month. This increased frequency reduced the likelihood x pump unavailability because of steam binding by a factor of 90 (3 shifts/day
30 days/month).
Cla
FEB 1 7 8 Multiple
Addressees
-2- As part of its efforts toward a final generic resolution of this issue, the staff surveyed the backleakage experience in operating plants following the implementation of monitoring procedures. Although the number of backleakage events varied from an average of less than one per reactor year at i large majority of plants to more than 100 per reactor year at others, none of the backleakage events that occurred during the review period appeared to have resulted in the steam binding of an AFW pump. This indicates that the various monitorina methods employed can be highly effective in preventing steam binding if backleakage occurs. For the plants with a high backleakage event rate, the installation of continuous monitoring systems with control room alarms was instrumental in providing for early warning to the operator and timely corrective action.
The results of the staff's regulatory analysis indicated that following the recommendations in Bulletin 85-01 would ensure that the contribution of AFN
pump steam binding to core melt frequency and public risk was sufficiently low and that there is no need for new recommendations beyond those in XE
The staff has concluded that the recommended monitoring actions of IE Bulletin 85-01 should be continued. However, although the staff has concluded that the currently assessed risk associated with this issue is reasonably low, it is still concerned about the generally unsatisfactory reliability of checik valves in operating plants. Plant operators should continue to be alert to the possible development of malfunctioning check valves, especially as the plant ages. They should be prepared to increase the monitoring frequency as needed and to implement appropriate recovery procedures to ensure that steam binding failure of the AFN
pumps does not occur.
IE Bulletin 85-01 recommended that procedural controls remain in effect (1)
until the completion of hardware modifications to substantially reduce the likelihood of steam binding, or (2) until it was superseded by action Implemented as a result of resolution of Generic Issue 93. This generic letter resolves Generic Issue 93 by perpetuating the recommendations of IE
Bulletin 85-01. In particular, all addressees should:
1. Maintain procedures to monitor fluid conditions within the AFW system each shift during times when the system is required to be operable.
This monitoring should ensure that fluid temperature at the AFN pump discharge is maintained at about ambient levels.
2. Maintain procedures for recognizing steam binding and for restoring the AFW system to operable status, should steam binding occur.
All addressees are requested to provide a letter of confirmation to the NRC
within 90 days of receipt of this generic letter indicating that the procedures discussed in this generic letter are in place and will be maintained. Confir- mation by addressees who did not previously receive IE Bulletin 85-01 is being requested because the staff believes that they would rely on these procedures as part of the actions to minimize the occurrence of the AFW pump steam binding problem.
Multiple
Addressees
-3- FEB 17 WC3 or affirma- Pursuant to 10 CFR 50.54(f), you are requested to submit under oath Commission, Document tion the letter of confirmation to the U.S. Nuclear Regulatory and distribution. This Control Desk, Washington, D.C. 20555, for reproduction Management and Budget under request for information is covered by the Office ofDecember blanket clearance number 3150-0011, which expires 31, 1989. Comment on burden and duplication should be directed to the Office of Management and Budget, Reports Management, Room 3208, New Executive Office Building, Washington, D.C. 20503.
following informa- Although no specific request or requirement is intended, ofthethis the cost generic letter:
tion would be helpful to the NRC in evaluating
1. Staff time to perform the requested confirmation and any needed followup actions.
2. Staff time to prepare requested documentation.
If there are any questions regarding this matter, please contact the Regional Administrator of the appropriate NRC regional office or your project manager in this office.
Sincerely, Frank J. ra Associate Director for Projects Office of Nuclear Reactor Regulation Enclosure: IEB 85-01 a-
Attachment.
OMB No.: 3150-0011 Expiration Date: 9/30/86
1EB 85-01 UNITED STATES
NUCLEAR REGULATORY COMMISSION
OFFICE OF INSPECTION AND ENFORCEMENT
WASHINGTON, D.C. 20555 October 29, 1985 FEEDWATER. PUMPS
IE BULLETIN 85-01: STEAM BINDING OF AUXILIARY
Addressees
construction reactor facility licensees and For Action - Those nuclear power in Attachment 1.
permit MCP) holders listed nuclear power reactor facilities.
For Information - All other
Purpose
holders of a poten- of this bulletin is to inform licensees and CP operating facilities The purpose that has occurred at certain tially serious safety problemof auxiliary feedwater (AFW) pumps as a result of involving the inoperability licensees and all PWR CP holders are requested to steam binding. Certain PWR similar events from occurring at their facili- take further action to prevent actions taken or planned.
ties and to document those
Description of Circumstances
leaked into AFW systems events have been reported where hot water has at Robinson 2 in 1981 Numerous the AFW pumps. Events and flashed to steam, disabling 3 in 1982 in 1981 were and 1983, and D. C. Cook 2 1984. Also through 1983, Crystal River in January Notice (IN)84-06, issued (INPO) issued summarized in IE Information of Nuclear Power Operations in January 1984, the Institute Robinson 2 and Farley.
Event Report (SER) 5-84 detailing'events at Report (SOER) 84-3 Significant Significant Operating Experience In April 1984, INPO issued at Surry 2 In 1983.
that discussed another event issued Analysis and Evaluation of Operational Data (AEOD) in The NRC's Office for "Steam Binding of Auxiliary Feedwater Pumps"
a case study report entitled these occurring This study identified 22 events since 1981; 13 of into AFW
July 1984. it appears that backleakage operating experience, feed in 1983. Based on In a number of plants, the two motor-driven pumps could occur in any PWR. a leaking into the steam generator; therefore, into a single pipe which feedsthe probability of steam binding in both trains of valve in that pipe increases often take suction from a common manifold;
AFW. Also, multiple AFW pumps steam bound because of leaking check valves, the therefore, if one pump becomes and cause other pumps to become steam bound.
common suction steam can heat the
~~ l g.
I .. tachmerot IEB 85-01 October 29, 1985 and transient conditions as well AFW capability is needed for normal shutdown case study examined the effects.of (steam steam as for accident mitigation. The AEODwas a loss of the power conversion binding on a sequence in which there other than loss-of-offsite power. A
generation) system after a transient shown this sequence to be a dominant probabilistic risk analysis had previously sample plant (Sequoyah). The case contributor to the core-melt risk forofa the AFW system as a result of steam study indicated that unavailabilityto the risk of core melt in PWRs. Monitoring binding contributes significantlypromptly correct the situation if backleakage AFW to detect backlealkage and to binding.
occurs would reduce the probability of steam of events involving backflow of hot Since the AEOD study was issued, a series 2 over a period of 7 days in water into the AFW system occurred at McGuire was taken. One of these events August 1984, before effective corrective actionline and damage to instruments. In involved overpressurization of the suction of hot water into AFW resulting November 1984, Catawba 1 experienced backflow of paint. In December 1984, the NRC's in fumes from Insulation and blistering determined that steam binding of AFW
Office of Nuclear Reactor Regulation a (NRR)
it high priority (Generic Issue 93, Steam was a generic issue and assignedPumps").
Binding of Auxiliary Feedwater and the need for short-term correc- To determine the extent of the safety issueconducted a survey in April and May of of tive actions, the NRC's regional offices 39 had temperature monitoring
1985. Of the 58 operating reactors surveyed, Of the remaining 19, 17 had normally AFW piping at least once per shift. pump discharge path in addition to check closed gate or globe valves in the as complete separation of trains that made valves, or some unique feature suchThe remaining 2 licensees have subsequently serious safety problems unlikely.
decided to monitor AFW piping temperature.
at all units, many have not Although some degree of action has been taken to detect or correct steam binding.
incorporated these actions into procedures assurance that effective actions will Without these provisions, there is little are requested to take the following continue. For this reason, the addressees actions:
1 Action for
Addressees
Listed in Attachment
1. Develop procedures for monitoringwhenfluid conditions within the AFW system on a regular basis during times the system is required to be that fluid temperature at the AFR
operable. This monitoring should ensure ambient temperature. Monitoring of pump discharge is maintained at about for precluding steam fluid conditions, if used as the primary basis binding, is recommended each shift.
This item is not intended to require elaborate instrumentation. A simple touching the pipe, is a satisfac- means of monitoring temperature, such as a tory approach.
binding and for restoring the AFW
2. Develop procedures for recognizing steam binding occur.
system to operable status, should steam
.ttachment IEB 85-01 October 29. 1985 until completion of hardware
3. Procedural controls should remain in effect likelihood of steam binding or modification to substantially reduce theas a result of resolution of until superseded by action implemented Generic Issue 93.
and implement procedures within 90
Schedule: For operating plants, developplants under construction, develop and For
-days of the date of this bulletin. after receiving an operating license or implement procedures within 90 days within 1 year of the date of provide an appropriate response and commitment this bulletin, whichever comes first.
a report describing the methods Re orting Requirements: Prepare and submit the date(s) that procedures and used to accomplish these actions. Include to be implemented. State the frequency training were implemented or scheduled operating plants, submit this report of monitoring of the temperature. For For plants under construction, within 120 days of the date of this bulletin.
receiving an operating license or submit the report within 120 days after whichever comes first. It is not within 1 year of the date of this bulletin, review.
netessary to submit the procedures for be submitted to the appropriate The written report, requested above, shall under provisions of Section Regional Administrator under oath or affirmation In addition, the original copy of
182a, Atomic Energy Act of 1954, as amended. report should be transmitted to the the cover letter and a copy of the attached Control Desk, Washington, DC
U. S. Nuclear Regulatory Commiss0on, Document
20555 for reproduction and distribution.
by the Office of Management and This request for information was approved Comment on burden and dupli- Budget under blanket clearance number 3150-0011.
of Management and Budget, Reports cation should be directed to the Office Bullding, Washington, DC 20503.
Management, Room 3208, New Executive Office is intended, the following informa- Although no specific request or requirement the cost of this bulletin:
tion would be helpful to the NRC in evaluating review and testing
1. staff time to perform requested
2. staff time to prepare requested documentation
I
Attachment IEB 85-01 October 29, 1985 this matter, please contact the Regional If there are any questions regarding NRC regional office or this office.
Administrator of the appropriate es 14. Taylor, S'rector ice of Inspection and Enforcement Technical Contacts: Mary S. Wegner% IE
(301) 492-4511 C. Vernon Hodge, IE
(301) 492-7275 Attachments:
- 1.
Addressees
for Action 1E Bulletins
'2. List of Recently Issued I
a-
Attachment 1 IEB 85-01 October 29. 1985
ADDRESSEES
FOR ACTION:
The following PWRs having an OL:
BYRON 1 CRYSTAL RIVER 3 DAVIS-BESSE
DIABLO CANYON 1 GINNA
INDIAN POINT 3 KEWAUNEE
MAINE YANKEE
MILLSTONE 2 NORTH ANNA 1 NORTH ANNA 2 PALISADES
POINT BEACH 1 POINT BEACH 2 PRAIRIE ISLAND 1 PRAIRIE ISLAND 2 RANCHO SECO
SAN ONOFRE 1 ST. LUCIE 1 ST. LUCIE 2 SUMMER
TMI I
TROJAN
TURKEY POINT 3 TURKEY POINT 4 WATERFORD 31 WOLF CREEK
YANKEE-ROWE
Attachment 2 IEB 85-01 October 29, 1985 LIST OF RECENTLY ISSUED IE BULLETINS
hued to*
Date of Bulletin Issue Isl _ oeto, eco sued No. Subject
8/24/84 All1 power *eactor
84-030 Refueling Cavity Water Seal fan :1ilities holding anOL or CP except Cov vlrt St.
Vrain
3/12/84 Al1 power reactor
84-02 Failures Of General Electric facilities holding Type HFA Relays In Use In an OL or CP
Class 1E Safety System facilities Cracks In Boiling Water 2/3/84 Wi1 BWR
Al
84-01 ith Mark I contain- Reactor Mark I Containment am ent and currently Vent Headers if i cold shutdown a' ith an OL for Action V. All ad other BWRs Ith an OL or CP for ii nformation
12/28/83 All power reactor
83-08 Electrical Circuit Breakers facilities holding With An Undervoltage Trip an OL or CP
Feature In Use In Safety- Related Applications Other Than The Reactor Trip System
12/09/83 Same as IEB 83-07
83-07 Apparently Fraudulent Sup. 2 Products Sold By Ray Miller, Inc.
10/26/83 Same as IEB 83-07
83-07 Apparently Fraudulent Sup. 1 Products Sold By Ray Miller, Inc.
7/22/83 All power reactor
83-07 Apparently Fraudulent facilities holding Products Sold by Ray Miller, an 0L or CP; Other Inc. fuel cycle facilities and Category B,
Priority I (processors and distributors)
material licensees A*
DL = Operating License CP
- Construction Permit
1 5ST OF , ENTLY ISSUED ENEFIC LETT S
Date of b em ic
1r I ssuIE~d To Sub ect. I sSuance
'Letter No.
t- 1. /20tO/a9 ALL POWER
GL 8R-02 "INTEGRATED SEFETY ASSESSMENT
(ISAP-8F II)" REACTOR
PROGRiAM II
LICENSEES
A1 /25/88 ALL LICENSEES
GL 69-01 "NRC POSITION1l O;J IGSCC IN BWlR
(-t Ic~i.r II( STAINLESS STEEL. OF OPERATING
BOILING WATER
P P1NbF," REACl ORS ANI,
HOLDERS OF
CONSTRUCT I ON
PERMITS FOR
14FRS
11 / 12/87 ALL. POWER AND
GL 87-1 6 NlJREG--1262. "ANSWERS TO
QUESTIONS AT PUBLIC MEETINGS NONP OWER
RE IMPLEMENTATION OF 1o CFR55 REACTOR
ON OFERAT ORS LICENSEES AND
LICENSES APPLICANTS FOR
LICENSES
ON DEFERRED 11/04/87 ALL HOLDERS OF
GL 87-15 POLICY STATEMENT
CONSTRUCT I ON
PLANTS
PERMITS FOR A
NUCLEAR POWER
PLANT
REQUEST FOR OPERATOR LICENSE 08 / 04 / 87 ALL. POWER
GL 87-14 REACTOR
SCHEDUiJLES
LICENSEES
INTEGRITY OF REQUALIFICATION 07/ 10/87 ALL NON-POWER
UL 87-13 REACTOR
EXAMINATIONS AT NON-POWER
LICENSEES
REACTORS
07 / 09/87 ALL LICENSEES
GL 87-12 50.54(f) LETTER RE. LOSS OF
OF OPERATING
PWRS AND
DUFING MID-LOOP OPERATION
HOLDERS OF
CONSTRUCT I ON
PERM ITS FOR
FPWR'S
RELAXATION IN ARBITRARY 06/23/87 * ALL OFPERATING
GL 87-11 LICENSEES,
INTERMEDI ATE PIPE RUFTURE
CONSTRUCTION
REQU I REMENTS
PERMIT
HOLDERS, AND
APPLI CANTS FOR
CONSTRUCTION
PERMITS
06/12/87 AL.L POWER
GL 87-10 IMPLEMENTATION OF 10 CFR
73.57, REQUIREMENTS FOR FBI REACT OR
LI CENSEES
CRIMINAL HISTORY CHECk:S