ML20043H359
| ML20043H359 | |
| Person / Time | |
|---|---|
| Site: | Zion File:ZionSolutions icon.png |
| Issue date: | 06/19/1990 |
| From: | Richter M COMMONWEALTH EDISON CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| IEB-88-008, IEB-88-8, NUDOCS 9006250287 | |
| Download: ML20043H359 (7) | |
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' Cornmonwealth Edison
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June 19, 1990 U.S. Nuclear Regulatory Commission Attn Document Control Desk Washington, D.C.
20555
Subject:
Zion Station Units 1 and 2 Supplemental Response to NRC Bulletin 88-08 and 88-08 Supplements 1 and 2 NRC_IlosknLNosuliD-1R5_and 50-304
References:
(a) NRC Bulletin 88-08, dated
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June 22, 1988.
(b) NRC Bulletin 88-08, Supplement 1. dated June 24, 1988.
(c) NRC Bulletin 88-08, Supplement 2, dr.ted August 4, 1988.
(d) W. Morgan (CECO) letter to U.S. NRC, dated October 3, 1988.
(e) M. Richter (CECO) letter to U.S. NRC, dated March 14, 1989.
Dear Sir:
References (a), (b), and (c) requested that licensees (1) review the l
I reactor coolant system (RCS) to identify any connected, unisolable piping that l
could be subjected to temperature distributions which would result in unacceptable thermal stresses and (2) take action, where such piping is identified, to ensure that the piping will not be subjected to unacceptable thermal stresses. References (d) and (e) provided Commonwealth Edison Company's (Ceco) previous responses for' Zion Station.
Reference (d), in response to Action 2 of Reference (a), indicated that sections of the Alternate Charging line (1RC065) Auxiliary Spray line l
(1RC145) and Charging Pump to Cold Leg Injection lines (1RC005, 1RC038, IRC071, IRC079) for Zion Unit I would be examined during the Fall 1989 l-ref ucithig outage.
In response to Action 3 of Reference (a), Reference (d)
I indicated that temperature monitoring devices (sensors) would also be installed on the Alternate Charging and Auxiliary Spray lines for Zion Unit 1 during the Fall 1989 refueling outage in order to support temperature l'
monitoring of these lines.
This letter reports on the actions performed during the Zion Unit 1 Fall 1989 refueling outage, and those actions which l-l will provide continuing assurance that piping integrity will be maintained.
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Additionally, this letter updates the actions which are being performed for Zion Unit 2.
l' 9006250287 900619 PDR ADOCK 05000295 I
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U.S. NRC Juno 19, 1990 l
I The scope of the Unit 1 piping examinations for Action 2 included volumetric examination of all piping base metal to the extent achievable by the ultrasonic method (enhanced technique), and surf ace examinations of all socket welds by the liquid penetrant method. The specific sections of the Alternate Charging, Auxiliary Spray, and Charging Pump to Cold 1,eg Injection lines which were examined were presented in Figures 2-1 through Z-6 of Reference (d). No indications were identified by the ultrasonic or the surface examinations. All documentation relating to these examinations will be retained at Zion Station. This completes Action 2 for Zion Unit 1.
For Action 3, temperature monitoring has been implemented for the Unit 1 Auxiliary Spray line (1RC145) in order to identify the temperature profiles downstream of isolation valve 1A0V-VC8146 (see Figure 1).
Temperature data is obtained upon each unit startup (from cold shutdown) and after manipulation of the isolation valve (lA0V-VC8146) to determine if valve leakage is occurring.
If isolation valve leakage is identified, additional temperature data will be obtained to determine if the Auxiliary Spray line is experiencing conditions which would cause a thermal f atigue concern.
Temperature sensors were initially installed on the Auxiliary Spray line (during the refueling outage) to support this monitoring.
However, subsequent to the refueling outage, tha temperature sensors were removed and temperature data is currently'oeing obtained (as previously described) through the use of a portable temperature meter.
Temperature data obtained to date has verified that no isolation valve leakage is occurring.
Temperature sensors were not installed on the Alternate Charging line (1RC065) during the refueling outage, since it was determined that temperature monitoring would not be required for the line.
Temperature monitoring was not implemented since the Alternate Charging line (which was previously isolated from the Charging Pump during unit operation by isolation valve 1A0V-VC8169) is being utilized, as of the current operating cycle, as the normal charging path (see Figure 1).
The original Charging line (1RC039), which had been in operation during the previous operating cycles of the unit, has been isolated (by isolation valve 1A0V-VC8147) from the Charging Pump.
This flowpath change is intended to conserve the f atigue life of the original Charging line (IRC039). At this time, it is expected that the Alternate Charging line (lRC065) will be utilized as the normal charging path for several operating cycles (possibly to the end of plant life).
As indicated previously, specific sections of the Alternate Charging line (IRC065) were non-destructively examined (ultrasonic and surface examinations) during the refueling outage, and no indications were identified.
In the event the Alternate Charging line is isolated (by valve 1A0V-VC8169) from the Charging Pump in the future, procedural controls are being established to ensure that temperature monitoring of the line will be implemented.
It is expected that the procedural controls will be established by July 31, 1990.
The Alternate Charging line will continue to be examined (non-destructive examinations) as required by the Inservice Inspection Program.
l lw/1032T:7
r U.S. NRC Juns 19,1990 The original Charging line (IRC039) was reviewed for the concerns of References (a), (b), and (c) prior to isolation from the Charging Pump. An evaluation of the piping configuration for this line concluded that thermal fatigue (due to isolation valve leakage) was not a concern due to the location of the inboard isolation check valve (1VC8379A) relative to the RCS. The check valve is located very close (approximately one foot) to the RCS (Loop "C" Cold Leg) flow streum, thus, any leakage is sufficiently mixed to preclude temperature stratification or temperature oscillations.
In response to Action 3 for the Unit 1 Charging Pump to Cold Leg Injection lines (IRC005, IRC038, IRC071, IRC079), procedures were implemented (prior to the Fall 1989 refueling outage) to identify any leakage past the boron injection tank (BIT) bypass valve (1S18925), or the BIT outlet isolation valves (IMOV-S18801A and IMOV-S18801B), en each unit startup (from cold shutdown) and after manipulation of the subject valves (see Figure 2).
To minimize the effects of any valve leakage, a temporary leak-off (drain) line L
was installed downstream of the subject valves during the Fall 1989 refueling outage. As indicated in Reference (d), the present leakage monitoring is considered an interim measure since a BIT removal modification is being performed (which will remove the BIT bypass line and valve, and the BIT outlet isolation valves).
During the refueling outage, the BIT bypass line was isolated (cut and capped) from the BIT outlet line, eliminating any possible leakage past the BIT bypass valve. During the next Unit I refueling outage (scheduled for September 1991), the modification is scheduled to remove the BIT and BIT outlet isolation valves, replace the existing Charging System isolation valves (IMOV-SI8803A and IMOV-SI8803B), and provide a mechanism for detection and removal of any leakage past those valves (Charging System isolation valves).
In accordance with Reference (a), CECO will notify the NRC upon completion of the BIT removal modification.
At this time, CECO would also like to provide an update on the actions which are being performed for Zion Unit 2.
The previous discussion on r
the Charging and Alternate Charging linea for Unit 1 also applies to Unit 2.
Therefore, following the current Spring 1990 refueling outage for Unit 2, the Alternate Charging line (2RC065) will be utilized as the normal charging path and the original Charging line (2RC039) will be isolated from the Charging
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Pump. During the previous Unit 2 refueling outage (Fall 1988),
non-destructive examinations (ultrasonic and surf ace examinations) were performed on the Alternate Charging line (2RC065), and no indications were identified.. Additionally, temperature sensors were installed on the Alternate Charging line during the Fall 1988 refueling outage in order to support m
temperature monitoring of the line. A review of the temperature data obtained during the previous operating cycle indicated that no fatigue due to thermal cycling had occurred; *.herefore, no additional actions are required prior to utilization of the Alternate Charging line as the normal charging path.
Since the Alternate Charging line will be utilized as the normal charging path during unit operation, temperature monitoring of the line will be discontinued.
In the event the Alternate Charging line is isolated f rom the w
lw/1032T 3 uman.mu.-.
U.S. NRC Juno 19,1990
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Charging Pump in the future, procedural controls will be established (by July 31, 1990) to ensure that temperature monitoring of the line will be implemented.
The Alternate Charging line will continue to be exanined (non-destructive examinations) as required by the Inservice Inspection Program. For the original Charging line (2RC039), which will be isolated from the Charging Pump, it was determined that thermal fatigue (due to isolation valve leakage) was not a concern based on an evaluation of the piping configuration (consistent with the previous discussion for the Unit 1 Charging line).
Additionally, during the current Unit 2 refueling octage, the temperature sensors which had been installed on the Auxiliary Spray Line (2RC145) and Alternate Charging line (2RC065) during the previous refue1Ang outage were removed.
For the Auxiliary Spray line, temperature data will continue to be obtained upon each unit startup (from cold shutdown) and after l
manipulation of the line's isolation valve (2A0V-VC8146), which is consistent with the monitoring activities previously described for the Unit 1 Auxiliary Spray line. The temperature data will be obtained using a portable j
temperature meter. As indicated previously for the Alternate Charging line, temperature monitoring has been discontinued since it (Alternate Charging line) will be utilized as the normal charging path during f uture operating cycles.
l As indicated in References (d) and (e), a BIT removal modification is being performed for Unit 2.
The scope of this modification is consistent with the Unit 1 BIT modification previously described. During the current Unit 2 refueling outage, the BIT bypass line was isolated (cut and capped) from the BIT outlet line, eliminating any possible leakage past the BIT bypass valve (2SI8925). During the next Unit 2 refueling outage (scheduled for January 1992), the modification is scheduled to remove the BIT and BIT outlet isolation valves (2MOV-SI8801A and 2MOV-SI8801B), replace the existing Charging System isolation valves (2MOV-SI8803A and 2MOV-SI8803B), and provide a mechanism for detection and removal of any leakage past those valves (Charging System isolation valves).
In accordance with Reference (a), CECO will notify the NRC upon completion of the BIT removal modification.
CECO would also like to report that in References (d) and (e),
inconsistent terminology was used when describing lines 1/2RC005, 1/2RC038 I
1/2RC071, and 1/2RC079. Although the line numbers were always identified correctly, these lines were described as " Charging Pump to Cold Leg Jnjection" lines and " Safety Injection Ccid Leg Injection" lines.
The correct description for these lines is " Charging Pump to Cold Leg Injection" lines.
It is hoped that the use of this inconsistent terminology did not create any confusion during the staff's review.
Iw/1032T:4
f U.S. NRC June 19, 1990 Please direct any questions that you may have concerning this response to this office.
Respectfully, h
n M. H. Richter Generic Issues Administrator Attachments:
Figure 1 - Simplified Diagram of Charging, Alternate Charging and Auxiliary Spray Lines Figure 2 - Simplifled Diagram of Charging Pump to Cold Leg Injection Lines cci A.B. Davis - Regional Administrator, Region III Senior Resident Inspector - Zion Station C. Patel - NRR Project Manager Subscribed and Sw rn to before m this d day 5%I'9 '5dv d13 N0tsstMM03 AM
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PIGURE 1 Simplified Diagram of Charging, Alternate Charging and Auxiliary Spray Lines To Loop
'A' 1HC065 IAOV-VC8169 g
Cold Leg
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i v1VC8379A 1AOV-VC8147 To Loop
'C' 1HCO39 Prom Charging Pumps
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- q and Cold Le6 Regenerative lleat Exchanger
-1VC8392 ivc 8393 To Pressurizer j acj ri r, mm Spray Line
,[v 1AOV-VC8146
- Spring loaded check valve normally closed -
opens only for regenerative heat exchanger overpressurization protection.
NOTE:
This figure is also applicable to Unit 2.
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