ML20064K489
| ML20064K489 | |
| Person / Time | |
|---|---|
| Site: | Point Beach  |
| Issue date: | 01/05/1981 |
| From: | Fay C WISCONSIN ELECTRIC POWER CO. |
| To: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| References | |
| IEB-80-24, NUDOCS 8101200150 | |
| Download: ML20064K489 (12) | |
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'i WISCONSIN Electnc m comr b
3 231 W. MICHIGAN. P.O. BOX 2046, MILWAUKEE. WI 53201
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3 January 5, 1981 Jd
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=82 Mr. James G. Keppler, Regional Director d
Office of Inspection and Enforcement, Region III
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U. S. NUCLEAR REGULATORY COMMISSION 799 Roosevelt Road Glen Ellyn, Illinois 60137
Dear Mr. Keppler:
DOCKET NOS. 50 266 ND 50-301 RESPONSE TO IE 3LULE TIN 80-24 POINT BEACH NUCLEAR PLANT, UNITS 1 AND 2 The subject bulletin described conditions at a power reactor facility which resulted in the undetected flooding of the containment floor with service water from multiple piping and fan cooler leaks.
The bulletin directed that licensees provide summary descriptions of all open cooling water systems inside containment and verify the existence of various means to detect the presence of leakage from such systems.
The Point Beach Nuclear Plant Units 1 and 2 have one open cooling water system inside containment.
A summary descrip-tion of the service water system is provided below.
The information is given in the format suggested by the bulletin.
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Mode of Operation:
During normal operation, the service water system provides approximately 515 gpm to each of four containment ventilation coolers.
Under design basis accident conditions, the service water flow to each cooler is increased to approximately 1,050 gpm.
Service water also provides approximately 100 gpm to the containment cavity coolers.
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Source of Water:
The service water source is Lake Michigan.
Extensive data on the water chemistry of Lake Michigan has been provided by Licensee in previous reports on non-radiological environmental monitoring.
A summary report of this monitoring was provided by letter to Mr. Edson Case dated July 3, 1978.
JAN.0 7 WBB1 gic120'\\#$C>
1 Mr. James G. Keppler January 5, 1981 1c.
Materials:
The piping used in the service water system associated with the containment coolers is ASTM A-53B carbon steel.
The containment ventilation cooler coils are copper tubes with vertical copper plate fins.
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Leakage Experience:
There has been no leakage experienced in this system during the 18 reactor-years of Point Beach Nuclear Plant Units 1 and 2 operation.
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History and Type of Repairs:
None.
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Provisions for Isolating:
Valving exists outside containment which permits independent isolation of each of the four containment ventilation coolers.
Final Facility Descrip-tion and Safety Analysis Report (FFDSAR)
Figure 9.6-2a presents a flow diagram of the service water system including the isolation valves.
Table 5.2-1 and Figures 5.2-11 and 5.2-11a present details of the isolation provisions.
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Provisions for Appendix J Testing:
Neither Appendix J to 10 CFR Part 50 nor the Point Beach Nuclear Plant Technical Specifications at Item 15.4.4.III establish any requirements for leakage rate testing of containment isolation valves of the type found in the service water system.
Although it may be i
possible to establish a program of Type C testing of these valves, no leakage rate testing is presently done.
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Instrumentation:
Each of the service water cooling lines from the containment ventilation coolers is provided with temperature, pressure and flow indicators.
The return lines from the cavity coolers are provided with temperature and pressure indicators.
The differential service water pressure across each containment ventilation cooler is also monitored.
All service water return lines from the containment are monitored by a common radioactivity monitor.
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Detection of Radioactive Contamination:
As mentioned above, radiation detector RE-16 monitors the service water discharge lines from the containment.
High radioactivity levels would be alarmed in the control room.
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Mr. James G.
Keppler January 5, 1981 The second portion of IE Bulletin 80-24 required licensees to take certain additional action to verify means for detection and monitoring of significant accumulations of water inside containment.
The design of the Point Beach Nuclear Plant Units 1 and 2 is such that relatively small accumulations of liquid in the containment A sumps are immediately alarmed in the control room.
These amounts are approximately 25 gallons for Unit 1 and 42 gallons for Unit 2.
These alarms cannot be cleared except by positive manual action by the reactor operator.
The sumps are drained by gravity to the auxiliary building sump when the operator opens a spring return to close switch in the control room.
Any drainage, and the time interval of drainage, from the containment building sump is recorded in the control room log.
Based on time to drain and intervals
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between alarms, an accurate and sensitive leakage rate deter-mination may be calculated.
The containment A sump is located in the reactor vessel pit.
Any leakage to the containment floor level will be directed to this sump via floor drains.
Any leakage originating from the containment ventilation coolers is collected in drain pans and piped directly to the containment sump.
Throughout its history of operations, the staff of the Point Beach Nuclear Plant have practiced containment leakage surveillance measures equal to or better than the measures suggested in the bulletin.
The containment leakage surveillance measures are described in PBNP Procedure PBNP4.ll found in the " Administrative control Policies and Procedures Manual", Volume 1.
For your convenience, a copy of this procedure is attached.
The key and controlling verification in this procedure is a multi-point plot kept at the control console of each reactor which is used to record and trend the five parameters described in the procedure.
Review of these parameters by the Shift Supervisor and Duty and Call Super-intendents assures that no significant accumulations of liquid would occur in the Point Beach containments.
We have, in addition to these measures, maintained a schedule of biweekly inspections of each containment since the units were put into operation.
These inspections include a visual observation of the containment elevation 8' ficors for liquid leaks.
The Technical Specification reporting requirements of Item 15.6.9.2.3 presently require the prompt notification (within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />) of any abnormal degradation discovered in a primary containment boundary.
We will notify the NRC of any service water system piping leaks within containment by means of a licensee event report submitted in accordance with this reporting provision.
Mr. James G. Keppler January 5, 1981 Based upon the past history of no significant contain-ment liquid leakage problems and the design of the Point Beach I
Nuclear Plant containment sump and sump drainage facilities, together with the leakage detection measures described above and in the attached procedure, we are confident that the accumulation of significant amounts of undetected liquids in the containments at Point Beach is extremely improbable and unlikely.
Accordingly, we do not plan any additional actions or equipment modifications in response to this bulletin.
Should you have any questions regarding this response, please contact me for clarification.
Very truly yours,
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C. W. Fay # 0 rector Nuclear Power Department Attachment Subscribed and sworn to before me This 5th day of January, 1981.
G A-*_4L-t,M M u Notary Publ'ic, State of Wisconsin My Commission expires 7-8-[
Copy to: Director, Office of Inspection and Enforcement NRC Resident Inspector l
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I PBNP 4.11 Revision 3 05-08-78 REACTOR CCOLANT SYSTEM L1:AKAGE DETERMINATION 1.0 PURPOSE The purpose of this instruction is to detail the method for following trends of reactor coolant system leakage and to determino quantities, in conformance with Technical Specifications commitments, Section 15.3.1.D.
Of first importance is the need to ascertain that there is no " exterior wall" Icakage from the reactor vessel, reactor system piping, ret : tor
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system valve bodics, pressurizer, reactor coolant pump bodics, or the reactor coolant cystem side of the steam generators. Of second importance is to ascertain that if any leaks occur in gasketed closures or packings of the reactor coolant system they are well under control with quantitics according to Technical Specifications commitments.
It is not the purpose of this instruction to quantitively determine reactor coolant system to other system cross-leakage or flow,. such as primary-to-secondary steam generator tube leakage (evaluated by Chemistry "N
and IIcalth Physics), or reactor coolant systen to component cooling leakage
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(under continuous evaluation by the component cooling radiation moni tor),
or reactor coclant system leakage to connecting systems such as reactor coolant drain or pressurizer blowdown or charging and volume control.
Such unenntrolled leakages as these noted above must remain so small in quantity for reasons of other limits that the leakages are not significant in the first evaluation limit of the Technical Specifications at 1 gpm.
2.0 METI!OD AND RESPO:iSIBILITY 2.1 As shown in the Technical Specifications Section 15.3.1.D, 'there are six methods of discovering or evaluating reactor coolant system leakage into the containment. They are as follows:
2.1.1 Air particle monitor 2.1.2 Radiogas monitor 2.1.3 Relative humidity 2.1.4 Sump A drainage 2.1.5 Computer and/or manual water balance 2.1.6 In-containment physical inspection
PENP 4.11
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.Page 2 2.2 In order to maintain evaluation type surveillance of reactor coolant system Icakage, the following observations and actions shall take place 2.2.1 During hot pressurized operation, the Control Operator shall periodically observe the air particle monitor reading, the radiogas monitor _rcading and the relative humidity reading.
2.2.2 During hot pressurized operation, the " eye ball" average readings or values of the following shall be plotted, if availabic, on a graph once per day:
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a.
Air particle monitor b.
Radiogas monitor c.
Relative humidity d.
Sump A drainage
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Computer and/or manual water balance leakage e.
number 3.
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Service water temperature 2.2.3 The six line graph shall be reviewed once per day by the Duty Shift Supervisor for Technical Specifications com-pliance.
t 2.2.4 The six line graph shall be reviewed once per week by the Duty and Call Superintendent and the Operations Superinten-dent.
2.2.5 A physical inspection inside containment for leakage eval-uation reasons may be ordered by t?.e Duty Shif t Supervisor, the Duty and Call Superintendent, or the operations Super-intendent, at any time felt necessary.
2.2.6 During hot pressurised operation, a physical inspection inside containment shall be made at. intervals not greater than once every two weeks, with time and results noted in the station log.
2.2.7 The Operations Superintendent shall periodically review the primary-to-secondary leakage and determine that when added to Sump A Icakage, the 1 gpm figure is not execeded or that additional Technical Specifications ovaluations occur as required.
PENP 4.11 Page 3 3.0 EVALUATION Some keys to evaluating in-containment leakage as itemized above are as follows:
3.1 A rising air particulato monitor reading (under steady-state con-ditions) can mean an increasing leak in the reactor coolant system, and, if it is the single leading indicator, may mean the leak is in the liquid phase of the reactor coolant system.
3.2 A rising radiogas monitor reading (under steady-state conditions) can mean an increasing leak in the reactor coolant system, and if it is the single leading indicator may mean the leak is in the gaseous
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phase of the reacter coolant system such as pressuri=er steam space b
, levels.
3.3 A rising relative humidity reading, under steady-state conditions, as the single leading indicator can mean an in-containment leak frca systems other than the reactor coolant system, a reactor coolant system liquid leak, or can mean an increasing service water system temperature.
Relative humidity readings should not exceed 50s if
't all in-containment systems are reasonably leaktight.
I 3.4 The gallons discharged from Sump A (under steady-state conditions) is the principal quantitative indicator and if rising in quantity can mean a leak' from in-containment systems or the reactor coolant system.
3.5 The water balance calculation, Item 3.4 above, Sump A drainage, f
is the basis for correlating quantitively the readings of 3.1, 3.2 and 3.3 above to approximate gallons per minute.
The,
correlations are important since Items 3.1, 3.2 and 3.3 above o
are fast indicators of a change in 1cakage.
l 3.6 The service water system temperature is inportant to evaluating j
corrections to trends of Sump A drainage and relative humidity, and a decreasing service water temperature can cause a decreasing humidity and increasing Sump A drainage.
For convenience to the evaluation, Technical Specifications Section 15.3.1.D l
1s attached to this instruction and follows.
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I,UtWAGE OF PEACTon cmi.;WT specification:
1.
If Icakage of reactor coolent from the reactor coolant system is indicated to execed 1 gpm by the deans availabic such as water inventory balances, monitoring equipment or dircet observation, a follow-up cvaluation of the safety implications shall be initiated as soon as practicable but no later than within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />.
Any indicated Icak shall be considered to be a real leak until it is determined that cither (1) a safety problem does not exist or (2) that the indicated leak cannot be substantiated by direct observation or other indication.
2.
If the indicated reactor coolant leakage is substantiated and is not evaluated as safe or is determined to exceed 10 gpm, reactor g
shutdown shall be initiated as soon as practicable, but no later i
than within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> after the leak was first detected.
3.
The nature of the leak as well as the magnitude of the leak shall be considered in the safety evaluation.
If plant shutdown is t
necessary per specification 2 above, the rato of shutdown and the conditions of shutdown shall be determined by the safety evaluation for cach caso and justified in writing es soon thercafter as practicable.
The safety evaluation shall assure that the exposure of offsite personnel to radiation from the primary system coolant activity is within the guidelines of 10 CPR 20.
Unit 1 Amendment No. 10 15.3.1-11 July 12, 1976 Unit 2 Amendment No. 12 4
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4.
If the Icahoge la dotcamined to be primary to necondary stram
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generator leakago in excenu of 500 CPD in cither steam generator, the reactor shall be chutdown and the plant placed in the cold shutdown s..
condition wJthin 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br /> after detcetion.
o 5.
If any reactor coolant 1cakage exists through a non-icolable fault in a reactor coolant system component (exterior wall of the reactor vessel,-piping, valvo body, preccuricer or steam generator head), the reactor shall be shutdown, and cooldown to the cold shutdown condition shall be initiated within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> of detection.
6.
The reactor shall not be restarted until the leak is repaired or until k'
the, problem is otherwise corrected.
7.
When the reactor is in power operation, tuo reactor coolant leak detcetion systems of different operating principles shall be in operation, with one of the two systems sensitive to radioactivity.
The systems sensitive to radioactivity may be out-of-service for 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> provided two other meanc are available to detect leakage.
8.
Secondary coolant gross radioactivity shall be monitored continuously by an air ejector gas monitor.
Secondary coolant gross radioactivity chall be measured weekly.
If the air ejector monitor is not operating, the secondaiy coolant l
l gross radioactivity chall be measured daily to evaluate etcaa generator leak tightness.
Basis.
I Water inventory balances, monitoring equip:acnt, radioactive tracing, boric acid cryctalline deposits, and phynical inspections can discloce reactor 1
Unit 1 Amendment tio. 10 15.3.1-12 July 12, 1975 Unit 2 Amendment 1:o. 12
coolant acaks. Any leak of radioactive fluid, whether from the reactor coolant system priunry boundary or not, can bn a serious probicm with respect to in-plant radioactivity contamination and cicanup or it could develop into a still more serious prob 1cm; and therefore, first indications
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ofsuchIcakagewillk)cfollowedupassoonaspracticabic.
Every reasonably effort will be made to reduce reactor coolant Icakage to the lowest possibic rato.
Although sorte Icak rates may be tolcrabic from a dose point of view, especially if they are to closed nystems, it must be recognized that leaks in the order of drops per minute through any of the walls of the primary system could be indicative of materials fai?. ee
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such as stroon corrosion cracking.
If depressurization, isolation and/or other pafety measures are not taken promptly, these small leaks could develop into much larger leaks.
Thereforo, the nat.ure of the Acak, as vc11 as the magnitude of the leakage, must be considered in the safety evaluation.
The provision pertaining to a non-isolabic fault in a reactcr cc,cl.inL t.ystem component is not intended to cover steam generator tube icnkag.cs, valve or packings, instrument. fittings or similar' primary system boundarics not indicative of major component exterior wall leakage.
N The specific Icak rate limit identified for primary-to-secondary lenhage of 500 GPD p<>r steam generator provides an additional margin of safety with regard to the potential f(r large steam generator tube failure in that action to shutdown the plant will be cnplicitly required at a low icakage rate threshold.
When the source and location cf Icakago has been identified, the situatio')
can be evaluated to detortine if operation can safely continue.
This evaluation wil.1 be perforned by the Manager's Supervisory Staff according
,i to routinc established in section 15.6.
Under those conditions, an Unit 1 Amend:vnt no. 10 15.3.1-13 Unit 2 Amendment No. 12 July 12, 1976
summ2grea1r.sge rase og 30 gpm has been establinhed.
The explained Icakago. rate of 10 9pn in alno well within the capacity of one charging pump, and makeup wo.uld be availabic even under the loss of offuite power m
condition.
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If leakage is to the containment, it may be identified by one or more of the following methods:
The containment air particulate monitor is sensitive to low leak c.
rates.
The rate of Icakage to which the instrument is sonnitive is 0.013 gin within 20 minutes, assuming thh prcsonce of corrosion product activity.
b.
The containment radiogas monitor is less sensitive but can be used as
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a backup to the air particulate monitor.
The sensitivity range of the instrument is approximately 2 gpm to greater than 10 gpm.
The humidity detector provides a backup to a. and b.
The sensitivity c.
range of the instrumentation is from approximately 2 gpm to 10 gpm.
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A leakage detcetion system which deterr.inne Icakage losses from water and steam synti.ps within the containment collects and measures moisturo condensed from the containment atr.osphere by cooling. coils of the main recirculation units.
This system provides a dependable and accurate means of measuring total leakage, including leaks from the cooling coils themselves which are part of the containment boundary.
Condensate flows from approximately 1/2 gpm to 10 gpm can be measured by this system.
Indication of leakage from the above sources shall be cause t'o require a e.
containment entry and limited inspection at rowcr of the reactor coolant system.
Visual inspection means, i.e., looking for steam floor wotness or boric acid crystalline formations, will be used.
Periodic inspections r..
Unit 1 Amendment No. 10 15.3.1-14 July 12, 1976 Unit 2 Amend.r.cnt No. 12
for indications of Icahnge within the containment will conducted to enhance early detcetion of problems and to accure bcct. on-line reliability.
If Icakage is to another cyctem, it will be detected by the plant radiation monitors and/or water inventory control.#
Costinuous monitoring of steam generator tubo 3cahage is accomplished by
(, alther ' he individual unit Air Ejector Radiation Monitor, the combined
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Air Ejector Radiation Monitor, or the Steam Gonorator Blovdown Radiation Monitor in conbination with periodic survoillance of the primary coolant cetivity.
Backup monitoring can be accomplished by sampling secondary a
cool, ant gross activity.
References FFDSAR Section 6.5, 11.2.3 s..
i Unit 1 Amendment No. 30 15.3.)-14a July 12, 1976 Unit 2 Amendment. No. 12 t
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