ML20128D382
| ML20128D382 | |
| Person / Time | |
|---|---|
| Site: | Beaver Valley |
| Issue date: | 11/25/1992 |
| From: | Calvo J Office of Nuclear Reactor Regulation |
| To: | Sieber J DUQUESNE LIGHT CO. |
| References | |
| IEB-80-18, IEIN-91-029, IEIN-91-064, IEIN-91-29, IEIN-91-64, IEIN-92-059, IEIN-92-061, IEIN-92-069, IEIN-92-070, IEIN-92-071, IEIN-92-072, IEIN-92-073, IEIN-92-59, IEIN-92-61, IEIN-92-69, IEIN-92-70, IEIN-92-71, IEIN-92-72, IEIN-92-73, TAC-M84935, NUDOCS 9212070253 | |
| Download: ML20128D382 (9) | |
Text
,
OCbb
&7 UNITED STATES 8
8'
' 7.
NUCLEAR REGULATORY COMMISSION
,i WASHING TON, D. C. 20555 g
/
November 25, 1992
- ...+
Docket No. 50-412 Serial No. BV-92-043 l
Mr. J. D. Sieber, Vice President Nuclear Group Duquesne Light Company Post Office Box 4 Shippingport, Pennsylvania 15077-00M
Dear Mr. Sieber:
1
SUBJECT:
OPERABILITY OF THE ALTERNATE MINIMUM FLOW PATHS FOR THE HIGH-HEAD SAFETY INJECTION PUMPS (TAC NO. M84935)
On August 20, 1992, the staff issued Information Notice 92-61, and on September 1,1992, the NRC staff issued special team inspection report No. 50-400/92-201 detailing staff findings and inspection activities pertaining to the effect and circumstances of a reported loss of high-head safety injection (HHSI) at the Shearon Harris Nuclear Power Plant (SHNNP) operated by Carolina Power & Light Company (CP&L).
This event was reported to the NRC in Licensee Event Report (LER) 50-400/91-008 on May 3, 1991. The LER was supplemented on May 15, 1991.
On November 6, 1992, the NRC issued i
Supplement I to NRC Information Notice 92-61 (Enclosure 1).
This event was examined in an Oak Ridge National Laboratory accident sequence precursor study of 1991 reactor operational events.
In that study, the event was assigned a conditional core damage frequency of 6.3x10E-3 per year.
The special team inspection centered around the alternate minimum flow (AMF) system piping and valves. The AMF system was installed after a Westinghouse 10 CFR Part 21 report and NRC Bulletin 80-18 were issued.
On October 13, 1992, CP&L submitted LER 50-400/91-008, Rev. 2, reporting additional system failure during the performance of an integrated functional test on the AMF system.
In this LER, CP&L also stated that the as-designed AMF system at SHNPP is being modified to remove the system weaknesses that have been previously identified.
During the course of staff review of the reported loss of HHSI at the SHNPP, the staff identified that a similarly designed AMF system is installed at Beaver Valley Power Station, Unit No. 2.
Because of the high safety significance of this issue, we request that you meet with the staff on December 10, 1992, to provide your justifications for the continued operability of the HHSI at BVPS-2.
Please be prepared to describe the AMF system configuration in detail, as well as your surveillance
\\
gem 7
,500J39 YM *
.,^w.
9212070253 921125 i \\ {J DR ADOCK 05000412
^V PDR i
c
Mr. J. D. Sieber testing experience to demonstrate that the AMF system will perform its functions as designed for all reactor pressure conditions.
You should also be prepared to discuss any planned modifications to the AMF system.
Sincerely, Original signed by Jose A. Calvo, Assistant Director for Region I Reactors Disision of Reactor Projects -l/11 Office of Nuclear Reactor Regulation
Enclosure:
As stated cc w/ enclosure:
See next page Distributigni Docket File NRC & Local PDRs PD l-4 Plant SVarga JCalvo SNorris ADeAgazio 0GC EAdensam NLe ACRS (10)
JFRogge, R1 0FFICE LA:PDI-4 PM:PDI-4/)N Dki-4 AD:DRPE /A/C WE S r}TE ADeAgazio:cn JStok JCalvo DATE l\\ /M92
// M/92
(/ /
92
// /;r/92
/ /
OFFICIAL RECORD COPY i
Document Name:
G:\\DEAGAZ10\\84935LET
Mr. J. D. Sieber Beaver Valley Power Station Duquesne Light Company Units 1 & 2 cc:
Jay E. Silberg, Esquire Bureau of Radiation Protection Shaw, Pittman, Potts & Trowbridge Pennsylvania Department of 2300 N Street, NW.
Environmental Resources Washington, DC 20037 ATTH:
R. Janati Post Office Box 2063 Nelson Tonet, Manager Harrisburg, Pennsylvania 17120 Nuclear Safety Duquesne Light Company Mayor of the Borrough of Post Office Box 4 Shippingport Shippingport, Pennsylvania 15077 Post Office Box 3 Shippingport, Pennsylvania 15077 Commissioner Roy M. Smith West Virginia Department of Labor Regional Administrator, Region I Building 3, Room 319 U.S. Nuclear Regulatory Commission Capitol Complex 475 Allendale Road Charleston, West Virginia 25305 King of Prussia, Pennsylvania 19406 John D. Borrows Resident Inspector Director, Utilities Department U.S. Nuclear Regulatory Commission Pub.ic Utilities Commission Post Office Box 181 180 East Broad Street Shippingport, Pennsylvania 15077 Columbus, Ohio 43266-0573 Director, Pennsylvania Emergency Man.agement Agency Post Office Box 3321 1
Harriahurg, Pennsylvania 17105-3321 Ohio EPA-DERR ATTN:
Zack A. Clayton Past Office Box 1049 Columbus, Ohio 43266-0149
UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF NUCLEAR REACTOR REGULATION WASHINGTON, D.C.
20555 November 6, 1992 NRC INFORMATION NOTICE 92-61, SUPPLEMENT 1:
LOSS OF HIGH HEAD SAFETY INJECTION Addressees All holders of operating licenses or construction permits for nuclear power reactors.
Purpose The U.S. Nuclear Regulatory Commission (NRC) is issuing this information notice to alert addressees to additional developments relating to the loss of high head safety injection (HHSI) function because of anomalies in the associated alternate minimum flow (AMF) system.
It is expected that recipients will review the information for applicability to their facilities and consider actions, as appropriate, to avoid similar problems.
- However, suggestions contained in this information notice are not NRC requirements; therefore, no specific action or written response is required.
Egifriotion of Circumstances On April 3,1991, Carolina Power & Light Company (the licensee) determined that the HHSI system for the Shearon Harris Nuclear Power Plant had been in a degraded condition during the previous operating cycle. The degraded condition resulted from relief valve and drain line failures in the AMF system for the charging / safety injection pumps (CSIPs) which would have diverted a sionificant amount of safety injection (SI) flow away from the reactor coolant system (RCS).
Additional description of the existing AMF system and additional discussion regarding the specifics of this event are contained in Information Notice 92-61, " Loss of High Head Safety Injection," dated August 20, 1992, and in NRC Special Inspection Report 50-400/92-201, dated September 1, 1992.
In addition, Figure 1 provides a schematic of the existing HHSI system at Shearon Harris.
To address NRC staff concerns regarding long-term operability of the existing HHSI system, the licensee committed to implement procedures to minimize the potential for gas or air intrusion into the AMF system and to perform additional testing of the AMF system.
On September 17, 1992, the licensee tested the HHSI AMF system. When the 1C5-746 motor-operated isolation valve was opened to test train 'A" of the
-HHSI AMF system (ICS-746 will stroke fully open in approximately 7 seconds),
relief valve 105-744 chattered slightly for several seconds and then 9211020211
l IN 92-61 Supplement 1 i
November 6, 1992-Page 2 of 3 successfully opened. When the 1C5-752 motor-operated isolation valve was opened (also requiring approximately 7 seconds)ificantly, the valve bellows to test train "B" of the HHS1 AMF system, relief valve 105-755 chattered sign failed, and the test was halted. Additional discussion regarding these tests is contained in NRC Inspection Report 50-400/92-17, dated October 1, 1992.
Discussion The licensee has indicated that the chattering of the ICS-755 relief valve is believed to have been caused by hydraulic effects associated with opening the 1C5-752 motor-operated isolation valve. The NRC staff believes that the fluid frictional and dynamic pressure loss characteristics of the long inlet piping upstream of 1C5-752 may have also contributed to the chattering.
The licensee indicated that the testing, disassembly, and examination of the 1C5-755 relief valve identified that the valve lift setpoint (2300 psi) had not changed, and that the bellows failure was caused by cyclic fatigue of an inside weld.
Static testing to verify the valve lift setpoint had been routinely performed, during the plant lifetime, whereas testing to simulate flow through the valve to assure proper operation and reseating apparently never was performed.
The Crosby relief valve technical manual states that chattering can affect the life, operation, and performance of a relief valve. The manual recommends that relief valves not have restricted inlets because restricted inlets can cause valve chatter.
The opening and closing of the motor-operated isolation valve in the existing HHSI AMF design at Shearon Harris restricts the inlet to the relief valve.
In addition, relief valves are generally designed to provide system ovarpressure protection and are not designed for continuous fluid throttling purposes.
The licensee also indicated that modifications will be made to the HHSI AMF system before restarting the plant from the current refueling outage.
Figure 2 provides a schematic of the proposed modifications to the HHS1 AMF system at Shearon Harris.
The licensee intends to install flow restricting orifices upstream of the motor-operated isolation valves and to remove the relief valves. The motor-operated isolation valve actuation logic will also be modified so~that the isolation valves will open when a safety injection signal is present coincident with RCS pressure above approximately 2300 psi.
The NRC staff is aware that other facilities may employ an HHS1 AMF design similar to the existing system at Shearon Harris. These include, but may not be limited to, Millstone Unit 3, Comanche Peak Units 1 and 2, Beaver Valley Unit 2, and Vogtle Units 1 and 2.
In addition, systems other than the HHSI j
AMF system may contain relief valves with restricted inlets, thus also making these valves potentially susceptible to chatter.
IN 92-61, Supplement 1 November 6, 1992 Page 3 of 3 This information notice requires no specific action or written response.
If you have any questions about the information in this notice, please contact the technical contact listed below or the appropriate Office of Nuclear Reactor Regulation (ERR) project manager.
Brian K. Grimes, Director Division of Operating Reactor Support Office of Nuclear Reactor Regulation Technical contact:
J. Ramsey, HRR (301) 504-1167 Attachments:
1.
Figure 1, Existing Shearon Harris High Head Safety Injection System 2.
Figure 2, Hodified Shearon Harris High Head Safety Injection System 3.
List of Recently issued NRC Information Notices
c fAttachment1 IN-92-61,~ Supplement l' November 6, 1992 Page 1 of 1 8%
8'
< 8HR"*I' 1CS 102 8
(5E At wTR MxF....
ICS-2141
........f i
CMS /31 S,
Put1P I A.gA -
5 y&
A Y
.., p.
r IC5 210 g
l 2 ' CM6/Si
~ ~ "
Pure Qi
,' V,
,?
1C-SAS T
s f
(
LS G
[
I....
...p..;..
Q g
1CS 196 p'
M T
t i
E d.
T r,
K% :
ggg Purip
. 3 -=
8 g
Damaged Valve a
.T...y...jz 1
Weld Leak /
1CS 732 j-j-
-Pipe Rupture 7
( N5T
... 4 1CS-m
[
I 1C 74.
{
l 1
4..
....J...
I Damised viive M-Cs 744 iCs-74a ics-7sa
[
ALTERNATE MINIMUM FLOW SYSTEM s
FIGURE 1 EXISTING SHEARON HARRIS HIGH HEAD INJECTION SYSTEM
. -y I
SI/ CHANGING FLOW I G 780 j,,
[ SI/O WIGING rump "A"'
c 1C5-745.
10 RMST FLOW ORIFICE 4
- c
{
] [
NORfW. MINIFLOW t
J I i
IIDIWW. INIFLOW gg
- t oC
?
l LOW ORIFICE SI/OWIGIIIB l SI/DIRAEINE FIN "C" FLOW r
9 1CS-753
'I
[
SI/O WIGING FLOW i
- $l/OWisINsPuMr*sa u
t 9
W
!2k it
.it
.r
. P, " r g
,?
@d" FIGURE 2-J MODIFIED SHEARON HARRIS HIGH HEAD INJECTION SYSTEM l
.a r..
r
-+
4
.i IN 92-61, Supplement 1 November 6, 1992 Page 1 of 1 LIST OF RECENTLY ISSUED NRC INFORMATION NOTICES Information Date of Notice No.
Subject Issuance Issued to 92-73 Removal of A Fuel 11-04/92 All holders of Ols or cps Element from A Re-for nuclear power reactors, search Reactor Core While Critical 92-59, Horizontally-Installed 11/04/92 All holders of OLs or cps Rev. 1 Motor-Operated Gate for nuclear power reactors.
Valves 92-72 Employee Training and 10/28/92 All U.S. Nuclear Regulatory Shipper Registration Commission Licensees.
Requirements for Trans-porting Radioactive Materials 91-64, Site Area Emergency 10/07/92 All holders of OLs or cps 5:op. 1 Resulting from A Loss for nuclear power reactors.
of Non-Class IE Uninterruptible Power Supplies 92-71 Partial Plugging of 09/30/92 All holders of Ols or cps Suppression Pool for nuclear power reactors.
Strainers At A Foreign BWR 92-70 Westinghouse Motor-Operated 09/2S/92 All holders of OLs or cps-Valve Performance Data for nuclear power reactors.
Supplied to Nuclear Power Plant Licensees 92-69 Water Leakage from Yard 09/22/92 All holders of OLs or cps Area Through Conduits for nuclear power reactors.
Into Buildings 91-29, Deficiencies Identified 09/14/02 All holders of OLs or cps Supp. 1 During Electrical Dis-for nuclear power reactors.
tribution System Func-tional Inspections DL = Operating License CP - Construction Permit
-.