ML18046A326
| ML18046A326 | |
| Person / Time | |
|---|---|
| Site: | Palisades  |
| Issue date: | 01/08/1981 |
| From: | Hoffman D CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| References | |
| IEB-80-24, NUDOCS 8101220395 | |
| Download: ML18046A326 (8) | |
Text
consumers Power company General Offices: 212 West Michigan Avenue, Jackson, Michigan 49201 * (517) 788-0550 January 8, 1981 Mr James G Keppler Office of Inspection and Enforcemept Region III U S Nuclear Regulatory Commission 799 Roosevelt Road Glen Ellyn, IL 60137 DOCKET 50-255 - LICENSE DPR PALISADES PLANT - RESPONSE TO IE BULLETIN 80 PREVENTION OF DAMAGE DUE TO WATER LEAKAGE INSIDE CONTAim'.lENT
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Consumers Power Company was requested by IE Bulletin 80-24 dated November 21, 1980, to address items concerning prevention of damage due to water leakage inside containment.
Our response is as follows:
Item 1 Provide a summary description of all open cooling water systems present inside containment.
Your description of the cooling water system must include:
(a)
Mode of operation during routine reactor operation and in response to a LOCA.
Response to Item l(a)
The Palisades Plant has one open cooling water system inside containment--the service water system.
During routine reactor operation, service water to containment is used to maintain containment temperature at approximately ll0°F via the containment air coolers.
There are four groups of coolers VHX-1, VHX-2, VHX-3 and VHX-4 with each group containing eight cooler units.
Service water outlet, from each of the four groups of containment air coolers, is through a 4" valve which_ bypasses a normally closed 8" valve.
During a design basis acci-dent, such as a LOCA, service water to the containment air coolers provides a redundant system to the containment sprays to mitigate the pressure transient.
During such operation, the larger 8" outlet valves from each group of coolers opens to permit increased service water flow.
(b)
Source of water and typical chemical content of the water.
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.;r Mr James G Keppler Palisades Plant January 8, 1981 Response to Item l(b)
The service water is supplied from Lake Michigan and nominally contains:
11 ppm Chlorides 5 ppm Silica 5 ppm Sodium 37 ppm Calcium 11 ppm Magnesium Trace amounts Iron, Cooper, Manganese.
(c)
Materials used in piping and coolers.
Response to Item l(c) 2 Material composition of all service water pipe inside containment is ASTM A-53 Grade A or B, or ASME SA-106 Grade B, or ASTM A-106 Grade B.
The cooler tubing is composed of copper.
(d)
Experience with system leak.age.
Response to Item l(d)
The Palisades Plant has twice experienced leakage in the tubing of the air coolers, once in 1972 and once in 1978.
Details on the cause of the leakage in 1972 are not know, however, it is suspected that they are similar to the leakage in 1978.
While the plant was purging containment in 1978, tubes on cooler groups VHX-1 and VHX-2 developed leaks.
The exhaust air on VHX-1 and VHX-2 is connected to the same air plenum that receives purge supply air.
The cold purge supply air froze the coils in VHX-1 and VHX-2, and thus, leaks developed.
The Palisades Plant has also experienced small leaks on the 4" outlet valves from the air coolers.
(e) History and type of repairs to coolers and piping systems (ie, replacement, weld, braze, etc).
Response to Item l(e)
Repairs on the air coolers during 1978 consisted of replacing 6 cooler units and brazing affected tubes in two other cooler units.
Similar repairs were made in 1972.
The periodic small leaks on the 4" outlet valves from the air coolers have been repaired by repacking or replacing the valves.
No other leaks have been experi-enced to date.
Mr James G Keppler Palisades Plant January 8, 1981 (f) Provisions for isolating portions of the system inside containment in the event of leakage including vulnerability of those isolation provisions to single failure.
Response to Item l(f) 3 Each of the four cooler groups, VHX-1, VHX-2, VHX-3, and VHX-4 have inlet control valves, CV-0862, CV-0865, CV-0870, CV-0869 respectively, and outlet check valves which can be used to isolate a defective cooler.
Service water lines to and from containment also have installed control valves, CV-0824 and CV-0847, which can be used to isolate service water from all the coolers and piping inside containment.
Design single failure considerations for the service water control valves mention-ed above were based on the design basis accidents in which service water to the air coolers is needed.
These valves fail open upon loss of air or electrical power.
Common mode failures, not considered here, may also affect these valves, however, service water to and fr.om containment can be isolated under any single or common mode failure through use of the hand jacks on CV-0824 and CV-0847.
(g)
Provisions for testing isolation valves in accordance with Appendix J to 10 CFR 50.
Response to Item l(g)
The valves mentioned in Item l(f) have no provisions for testing in accordance with Appendix J, 10 CFR 50.
(h)
Instrumentation (pressure, dew point, flow radiation detection, etc) and procedures in place to detect leakage.
Response to Item l(h)
The Palisades Plant has the following methods to detect leakage in the service water system:
- 1.
Each air cooler has a drip pan installed beneath it with a level switch which causes annunciation in the Control Room when level in the drip pan reaches 611
- Each level swit~h has its own annunciator so recognition of a leak in a particular air cooler is possible.
- 2.
The containment sump, to which service water leakage would drain,. has two.
pressure switches which cause annunciation in the Control Room when level in the sump reaches 4".
In addition to this, the sump also has two level indi-cator alarms (LIAs) which read out in the Control Room and cause annunciation in the Control Room when level in the sump reaches 12".
Each LIA has its own annunciator.
L Mr James G Keppler Palisades Plant January 8, 1981 4
- 3.
Flow signals on the inlet and outlet service water to containment are measur-ed and processed so that a difference in flow of 85 gpm causes annunciation in Control Room.
This system has proved to be unreliable.
The Palisades Plant has existing procedures which inform the operator on the nature of the annunciations mentioned above and actions to be taken in response to the alarm.
These procedures for the above items are:
(a)
SOP-5 Containment Air Cooling and Hydrogen Recombining; SOP-40 Annun-ciators (b)
SOP-17B Dirty Radioactive Waste System; SOP-40 Annunciators (c)
SOP-5 Containment Air Cooling and Hydrogen Recombining; SQp-40 Annun-ciators.
(i) Provisions to detect radioactive contamination in service water discharge from containment.
Response to Item l(i)
The Palisades Plant has no process liquid monitor at the service water discharge from containment, however, it does have a process liquid monitor at the service water discharge to Lake Michigan with indication and annunciation in the Control Room.
Item 2 For plants with open cooling water systems inside containment, take the following actions:
(a)
Verify existence or provide redundant means of detecting and promptly alert-ing Control Room operators of a significant accumulation of water in contain-ment (including the reactor vessel pit if present).
Response to Item 2(a)
The Palisades Plant has two level indicator alarms, LIA-0358, and LIA-0359, with indication and alarm in the Control Room which monitor liquid level in the con-tainment sump.
The sump is 3 1/2' deep and 22' in diameter.
Liquid level via the LIAs can be monitored to a height of 10' ~
The alarm via the LIAs is annun-ciated in the Control Room when level in the sump reach 1 1
- The two LIAs and associated level transmitters and power supplies are electrically separated in left/right channel convention and provide redundant means of detecting and prompt-ly alerting Control Room operators of a significant accumulation of water in con-tainment.
(b)
Verify existence or provide positive means for Control Room operators to determine flow from containment sump(s) used to collect and remove water from containment.
Mr James G Keppler Palisades Plant January 8, 1981 Response to Item 2(b)
Flow from the containment sump is positively determined from level changes on the LIAs.
5 (c)
Verify or establish at least monthly surveillance procedures, with appro-priate operating limitations, to assure plant operators have at least two methods of determining water level in each location where water may accumu-late.
The surveillance procedures shall assure that at least one method to remove water from each such location is available during power operation.
In the event that either the detection or removal systems become inoperable, it is recommended that continued power operation be limited to seven days or added surveillance measures be instituted.
Response to Item 2(c)
Surveillance measures have been implemented in an existing surveillance test, DW0-1, which is performed daily/weekly.
These measures include:
- 1.
Verification that containment sump level is below 12" on both LIA-0358 and LIA-0359.
- 2.
Verification that both LIA-0358 and LIA-0359 are within 4% of each other.
- 3.
Verification that containment sump drain valves CV-1103 and CV-1104 can be stroked.
These measures, in addition to the other methods mentioned in Item l(h) to detect* leakage and the weekly visual surveillance of part of the 590' elevation when control rod seal leakage rates are taken, assure that leakage in containment
. will not go unnoticed.
(d)
Review leakage detection systems and procedures and provide or verify ability to promptly detect water leakage in containment and to isolate the leaking com-ponents or system.
Periodic containment entry to inspect for leakage should be considered.
Response to Item 2(d)
The leakage detection systems presented in l(h) and the isolating provisions of l(f) provide for prompt detection and isolation of the leaking components within containment.
Periodic containment entry.to acquire control rod drive seal leak-age rates, as mentioned in Item 2(c), already exist.
(e)
Beginning within 10 days of the date of this bulletin, whenever the reactor is operating and until the measures described in (a) through (d) above are implemented, conduct interim surveillance measures.
The measures shall
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Mr James G Keppler Palisades Plant January 8, 1981 6
include where practical (considering containment atmosphere and ALARA considera-tions), a periodic containment inspection or remote visual surveillance to check for water leakage. If containment entry is impractical during operation, perform a containment inspection for water leakage on the first plant shutdown for any reason subsequent to receipt of this bulletin.
Response to Item 2(e)
Weekly containment entries are being performed to search for water leakage on the lower level of containment and results of the inspections are documented in the Shift Supervisor's logbook.
The measures described in (a) through (d) above have now been implemented.
(f) Establish procedures to notify the NRC of any service water system leaks within containment via a special Licensee Event Report (24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> with written report in 14 days) as a degradation of containment boundary.
Response to Item 2(f)
Based on the fact that Service Water System pressure is nominally 65 to 70 psig (at pump discharge), and since the pressure drop across the containment air coolers under accident conditions is 7.0 psid (per FSAR, Table 6.5), leakage will always be into containment, even under worst case MSLB accident conditions.
As a result, it appears that nominal service water leakage should not be report-ed as a breach of containment integrity.
It is not evident that all service water leaks within containment would repre-sent a degradation of containment integrity.
Gross leakage would require render-ing one or more containment air coolers inoperable, and would be reported to NRC as operation in a degraded mode permitted by the Limiting Conditions for Operation of Technical Specification 3.4.
Item 3 For plants with closed cooling water system inside containment, provide a summary of experiences with cooling water system leakage into containment.
Response to Item 3 The Palisades P~ant has the following closed cooling water systems inside contain-ment.
- l.
Component cooling water system.
- 2.
Shield cooling system.
3, Primary coolant system and associated chemical and volume control system.
- 4.
Feedwater system and associated steam generator blowdown system.
Through personal communication and a review of maintenance orders from 1972 to 1980, the following summary of experience has been compiled:
i Mr James G Keppler Palisades Plant January 8, 1981 *
- 1.
The component cooling water system inside containment has had no leakage problems.
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- 2.
The shield cooling system has had periodic small leakage from relief valves.
- 3.
The primary coolant system and associated chemical and volume control system has had periodic small leakage from pressure indicator controllers or pressure switches (PIC, PS-0220, PIC, PS-0221) downstream of the letdown orifice valves, a broken vent pipe on the regenerative heat exchanger, and seal leakage on the control rod drive apparatus.
- 4.
The feedwater system and associated steam generator blowdown system inside containment has experienced no leakage inside containment.
Item 4 Provide a written report, signed under oath or affirmation, under the provisions of Section 182a of the Atomic Energy Act of 1954, in response to the above items within 45 days of the date of this bulletin.
Include in your report, where appli-cable, your schedule for completing actions in response to Items 2(a) through (d).
Your response should be sent to the Director of the appropriate Regional Office with a copy forwarded to the Director, NRC, Office of Inspection and Enforcement, Washington, D C 20555.
Response to Item 4 Items in 2(a) through (d) have been completed.
David P Hoffman Nuclear Licensing Administrator CC Director, Office of Nuclear Reactor Regulation Director, Office of Inspection and Enforcement NRC Resident Inspector - Palisades Plant
I CONSUMERS POWER COMPANY Palisades Plant IE Bulletin 80-24 Docket 50-255 License DPR-20 At the request of the Commission and pursuant to the Atomic Energy Act of 1954 and the Energy Reorganization Act of 1974, as amended, and the Commission's Rules and Regulations thereunder, Consumers Power Company submits our response to IE Bulletin 80-24 dated November 21, 1980, entitled, "Prevention of Damage Due to Water Leakage Inside Containment".
Consumers Power Company's response is dated January 8, 1981.
CONSUMERS POWER COMP.ANY By (Ej3 6 rW dr*';
RB DeWitt, Vice President Nuclear Operations Sworn and subscribed to before me this 8th day of January, 1981.
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Linda K Carstens, Notary Public Jackson County, Michigan My commission expires June 10, 1981.