ML19332A780
| ML19332A780 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 07/31/1980 |
| From: | Fehringer J, Rockhold H EG&G IDAHO, INC., EG&G, INC. |
| To: | Nerses V Office of Nuclear Reactor Regulation |
| References | |
| CON-FIN-A-6258 EGG-EA-5214, TAC-11290, NUDOCS 8009180309 | |
| Download: ML19332A780 (32) | |
Text
_ . _ _ _ _ _ . . _
n p E Idaho. lac
, FORM EG4G.396 (f4ev It-79)
INTERIM REPORT Accession No.
Report No. EGG-EA-5214 Crntract Program or Project
Title:
Systems Engineering Support Subject of this Document Safety Evaluation of the Inservice Testing Program for Pumps and Valves at the Millstone Unit 2 Nuclear Plant (Docket No. 50-336) for the Period April 26, 1979, through October 25, 1980 Type of Document:
Safety Evaluation Report Author (s):
~
J. M. Fehringer H. C. Rockhold
. D;te of Document:
July 1980 Responsible NRC Individual and NRC Office or Division:
Victor Nerses, NRC-DE This document was prepared primarily for preliminary or internal use. it has not received full review and approval. Since there may be substantive changes, this do ument should not be considered final.
EG&G Idaho, Inc.
Idaho Falls, Idaho 83415 Prepared for the U.S. Nuclear Regulatory Commission Washington, D.C.
Under DOE Contract No. DE-AC07 76lD01570 NRC FIN No. A6258 n ,, , - - - -
,: _t INTERIM REPORT
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CONTENTS
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I. Introduction .............................................. 1 II. Pump Testing Program ...................................... 2 I I I . V al ve Te s ti n g P rog ram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 IV. A t t ac h m en t I . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 V. Attachment II ............................................. 25 VI. Attachment III ............................................ 29 VII. Attachment IV ............................................. 30 O
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. I. Introduction
. Contained herein .is a safety evaluation of the pump and valve inservice testing (IST) program submitted by Northeast Nuclear Energy Company (NNECO) for its Millstone, Unit 2, nuclear plant.
The program applies to Unit 2 for the period April 26, 1979 through October 25, 1980. The working session with NNECO and Millstone Unit 2 representatives was conducted on-5-23-79 and 5-24-i9. The licensee re-submittal was issued on 6-25-79 and was reviewed by EG&G Idaho, Inc., to verify compliance of proposed tests of safety related class 1, 2, and 3 pumps and valves with.
requirements of'the ASME Boiler and Pressure Vessel Code,Section XI,1974 Edition, through the Summer of 1975 Addenda.
NNECO has also requested relief from the ASME Code from testing specified pumps and valves because of practical reasons. These requests have been evaluated individually to determine whether they have significant risk implications and whether the tests, as required, are indeed impractical. -
The evaluation of the pump testing program and relief requests for pumps is contained in Section II below; the evaluation of the
, valve testing program and associated relief requests is contained in Section III. All evaluations for Section II and III are the recommendations of EG&G Idaho, Inc.
Appendix J exemption requests for category A valves currently being reviewed by the NRC are contained in Attachment I.
Category A, B, and C valves that meet the requirements of the ASME Code Section XI and are not exercised every 3 months are contained in Attachment II.
A listing of P&ID's used for this review is contained in Attachment III.-
Valves that are never full stroke exercised or that have a testing interval greater than each refueling outage and relief requests with insufficient technical basis where relief is not recommended are summarized in Attachment IV.
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II. Pump Testing .
The IST program submitted by NNEC0 for its Millstone Unit 2 .
nuclear plant was examined to verify that all safety related pumps were included in the IST program and that those pumps are subjected to the periodic tests as rcquired by the ASME Code,Section XI. All safety related pumps were found to be included in the IST program and, except fcr those pumps identified below for which specific relief from testing has been requested, the pump tests and frequency of testing comply with the code. Each Millstone Unit 2 request for relief from testing pumps, the code requirement for testing, basis for requesting relief, and EG&G's evaluation of that request is summarized below.
A. All Systems
- 1. Relief Request The licensee has requested specific relief from the requirements of Section XI Table IWP-3100-2 for the method of testing and allowable ranges for pump vibration measurements on all safety related pumps. ,
Code Requirement An inservice test shall be conduct +d on all safety related pumps, nominally once each month during normal plant operation. Each inservice test shall include the measurement, observation, and recording of all
. quantities in Table IWP-3100-1, except bearing temperature, which shall be measured during at least one inservice test each year.
The allowable ranges in instrvice test quantities in relation to the reference values, are tabulated in 4 Table IWP-3100-2. In the event these ranges cannot be met, the owner shall specify in the pump record the reduced range limits to allow the pump to fulfill its function, and those limits shall be used in lieu of the ranges given in Table IWP-3100-2 for the monthly pump test.
Licensee's Basis for Requesting Relief To meet the vibration monitoring requirements of ASME Section XI, Subsection IWP, exception is taken to the specific vibration requirements of IWP and an .
alternate, more effective vibration signature analysis program as described herein, is proposed. During the inservice pump test, vibration data shall be acquired in the form of a " vibration signature" rather than a 2
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simple reading of overall vibration amplitude. The vibration signature shall consist of a plot of vibration velocity in units of inches per second, versus frequency in cycles per second, normally using a frequency range of 0 to 500 cycles per second. The vibration signature analysis approach provides a more
, reliable means of detecting a deterioration of pump mechanical condition, a means of diagnosing the cause of a problem and a more accurate assessment of vibration severity. The periodically acquired vibration signatures shall be compared to a baseline reference signature and analyzed for changes in amplitude peaks exceeding a threshold value. Criteria for evaluation of changes as to cause, severity and the establishment of the Alert and Required Action Ranges will be specified in the NNEC0 procedures and the IST program.
Vibration measurements are made typically with an accelerometer mounted at a reference location on an i equipment bearing housing and the output processed by a spectrum analyzer to produce a hard copy vibration signature.
The measurement locations to be used for monthly and baseline vibration signature data shall be established by NNEC0 procedures.
Evaluation We agree with the licensee's basis, and therefore feel relief should be granted from Section XI Table IWP-3100-2 for pump vibration measurements on all safety related pumps. The licensee has demonstrated that the proposed alternate means of testing meets the intent of the code. We feel this vibration signature analysis will adequately evaluate the mechanical condition of these safety related pumps and provide sufficient information for predicting pump failure.
- 2. Relief Request The licensee has r~equested specific relief from the Section XI requirement to measure bearing temperature yearly and proposed to evaluate bearing performance using a vibration signature analysis for each safety 4
. related pump.
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m Code Requirement -
An intervice test shall be conducted on all safety .
related pumps, nominally once each month during normal plant operation. Each inservice test shall include the measurement, observation, and recording of all quantities in Table IWP-3100-1, except bearing temperature, which shall be measured during at least one inservice test each year.
Licensee's Basis for Requesting Relief Bearing metal temperature monitoring can be effective in detecting bearing problems. However, none of the tabulated pumps have the permanently installed temperature sensors required to measure bearing metal temperature (i.e., outer race of antifriction bearing or babbitt lining of sleeve bearing). The annual measurement of bearing housing temperature is far less effective in detecting bearing problems than the monthly performance of vibration signature analysis being performed by NNECO. The pumps listed in .
Table IWP do not have adequate design provisions to allow meaningful bearing temperatures to be taken.
Auxiliary feedwater (3 pumps) and HPSI (3 pumps) bearing housings are water jacketed. Thus measured contact temperatures are not indicative of actual bearing metal temperature.
Boric acid (2 pumps), spent fuel pool cooling (2 pumps) and containment spray (2 pumps) bearings are mounted in a massive oil filled reservoir which is in direct contact with the pumped fluid.
Thus measurement of housing temperature is not indicative of bearing condition.
LPSI (2 pumps) and chilled water (2 pumps) have no pump end bearings. Driver end bearings are mounted in heavy flanges attached to the driver.
The mass of this housing and the effects of motor heat on housing temperature prevent contact measurements from being indicative of bearing conditions. .
Charging (3 pumps) pump bearir.gs are recessed in a massive housing in the casing. The mass of the -
housing prevents contact measurements from being indicative of bearing temperature.
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RBCCW (3 pumps) pump bearings have an oil reservoir and a heavy housing. Contact measurements of housing temperature may not be indicative of actual bearing temperatures.
Service water pump bearings are under water and inaccessible.
In general, as internal bearing metal temperatures increase due to bearing overload, improper lubrication or faulty installation, etc., much of the heat will be dissipated throughout the relatively massive housings, oil reservoir and attached' casing. As a result, bearing housing temperatures will respond much less than bearing metal temperature, greatly reducing the sensitivity to detect bearing heatup problems.
Another important requirement to assure reliable bearing temperature monitoring is that it be continuous, not periodic. Experience indicates that failing bearings whether anti-friction type or sleeve
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often exhibit fluctuations between normal and abnormal metal temperatures. A good example is the babbitt lined sleeve bearing which will initially experience a rapid rise in temperature and then return to normal temperatures after the bearing wipes and clearances open up causing increased oil flow. The abnormal temperature rise would most probably go undetected unless continuously monitored.
The monthly vibration signature analysis conducted by NNEC0 will detect bearing problems at a very early stage. At the onset of a bearing problem, low level vibration will be generated at characteristic frequencies depending on the nature of the problem.
The low level vibration typically amounts to less than 1% of the overall' vibration amplitude and therefore cannot be detected by a simple amplitude monitoring program conforming to IWP minimum requirements.
However, the low level changes in bearing distress frequencies are routinely detected in the MP-2 signature analysis program and analyzed to pinpoint the cause.
As an alternate the pump vibration signature tests will be performed, recorded and analyzed monthly. Signature will be measured as velocity spectrum between zero and 500 hertz. Signatures will be evaluated using the acceptance-criteria of. Figure IWP-1. This monthly analysis will provide more meaningful analysis of pump bearing condition than annual measurement of bearing
. temperature.
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l Evaluati on -
( We agree with the licensee's basis, and therefore feel .
that relief should be granted from the requirements of Section XI to measure bearing temperature. The l licensee 'has demonstrated that measuring the ' bearing l- cooling medium temperature and not bearing race
, temperature will not provide meaningful data to ,
l evaluate pump performance. Provisions to measure bearing race temperatures do not exist. Bearing performance and wear will be analyzed using the vibration signature analysis. We feel that the proposed alternate testing method will more effectively evaluate-bearing performance than a contact temperature l reading on the bearing housings for these pumps.
- 3. Relief Request l
The licensee has requested specific relief from the
! monthly requirement of Section XI IWP-3230 (c).
Code Requirement ,
If the deviations from the measured pump parameters fall within the " Required Action Range" of Table -
IWP-3100-2, the pump shall be declared inoperative and not returned to service until the condition has been corrected. The corrective action shall be considered completed when a satisfactory inservice test has been conducted in accordance with IWP-3111.
l Licensee's Basis for Requesting Relief It is the position of NNECO that the operating status of a pump is best determined by plant management after an Engineering and Operations review of test data.
NNECO therefore requests relief from IWP-3230 (c) which requires that a pump tx3 declared inoperative when performance data fall into the " required action range."' Corrective action will be further. defined in performance test implementing procedures.
Evaluation t
We feel the licensee has not shown adequate justification for not complying with the requirements of Table'IWP-31-2 of Section XI. Therefore we r
recommend that relief not be granted unless the licensee provides additional information that specifically identifies what conditions determine required action.
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. III. Valve Testing Program Evaluation The IST program submitted by NNEC0 for its Millstone Unit 2 nuclear plant was examined to verify that all safety related valves were included in the program and that those valves are subjected to the periodic tests required by the ASME Code,Section XI, and the NRC positions and guidelines. All safety related valves were found to be included in the IST program and, except for those valves identified below for which specific relief from testing has been requested, the valve tests and frequency of testing comply with the code requirements and the NRC positions and guidelines listed in General Section A. Also, included in the General Section A is the NRC position and valve listings for testing of valves that perform a pressure isolation function and a procedure for the licensee's use to incorporate these valves ipto the IST program. Each NNECO request for relief from testing valves, the code requirement for testing, NNEC0 basis for requesting relief, and the EG&G Idaho evaluation of that request is summarized (B through E) below and grouped according to ea'.h specific system.
A. General Considerations
- 1. Testing of Valves which Perform Pressure Isolation Function There are several safety systems connected to the
, reactor coolant pressure boundary that have design pressures that are below the reactor coolant system operating pressure. .There are redundant isolation valves forming the interface between these high and low pressure systems to prevent the low pressure systems from being subjected to pressures wh!ch exceed their design limit. In this role the valves are performing a pressure isolation function.
It'is our view that the redundant isolation provided by these valves regarding their pressure isolation function is important. We consider it necessary to provide assurance that the condition of each of these valves is adequate to maintain this redundant isolation and system integrity. For this reason we believe that some methods, such as pressure monitoring, radiography,
' ultrasonic testing, leak esting, etc., could be used to assure that the condition of each valve is satisfactory to maintain this pressure isolation function.
In the event that leak testing is selected as the appropriate method for achieving this objective the staff believes that the following valves should be categorized as A or AC and leak tested in accordance with IWV-3420 of Section XI of the applicable edition of the ASME Code. These valves are:
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2-SI-217, 706 A, 215 -
2-SI-227, 706 B, 225 2-SI-237, 706 C, 235 .
2-SI-247, 706 D, 245 2-SI-651, 652 2-SI-618, 628, 638, 648 We have discussed this matter and identified the valves listed above to the licensee. The licensee has agreed to consider testing each of these valves and to categorize these valves with the appropriate designation depending on the testing method selected.
Whatever the licensee selects as the testing method to be used to determine each valve's condition, the licensee will provide to the NRC for evaluation on a valve-by-valve basis the details of the method used that clearly demonstrates the condition of each valve.
- 2. ASME Code Section XI Requirements .
Subsection IWV-3410(a) of the Section XI Code (which discusses full stroke and partial stroke) requires that .
Code Category A and B valves be exercised once every 3 months, with the exceptions as defined in IWV-3410(b-1), (e), and (f). IWV-352G a) requires that -
Code Category C valves be exercised once every 3 months, with the exceptions as defined in IWV-3520(b).
IWV-3700 requires no regular testing for Code Category E valves. Operational checks, with appropriate record entries, shall record the position of these valves before operations are performed and after operations are completed and shall verify that each valve is locked, or sealed. The limiting value of full stroke time-for each power operated valve shall be identified by.the owner and tested in accordance with IWV-3410(c). In the above exceptions, the code permits the valves to be tested at cold shutdown where:
- a. It is not practical to exercise the valves to the position required to fulfill their function or to the partial position during power operation. .
- b. It is not practical to observe the operation of the valves (with fail-safe actuators) upon loss of actuator power.
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The staff stated its position to the licensee that -
check valves whose safety function is to open are expected to be full-stroked. If only limited operation is possible (and it has been demonstrated by the 8
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licensee and agreed to by the staff), the check valve shall be partial stroked. Since disk position is nat always observable, the NRC staff stated that verification of the plant's safety analysis design flow rate through the check valve would be an adequate demonstration of the full-stroke requirement. Any flow rate less than design will be consider ed part-stroke exercising unless it can be shown that the check valve's disk position at the lower flow rate would be equivalent to or greater than the design flow rate through the valve. The licensee agreed to conduct his I
flow tests to satisfy the above position.
- 3. Cold Shutdown Testing Definition Inservice valve testing at cold shutdown should commence not later than 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> af ter shutdown and continue until complete or until the plant is ready to return to power. Completio1 of all valve testing is not a prerequisite to return to power. Any testing not completed at one cold shutdawn should be performed
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during the subsequent cold sautdowns to meet the code required testing frequency.
- 4. Cold Shutdown Testing The code states that, in the case of frequent cold shutdowns, valve testing need not be performed more often than once every 3 months for Catt. gory A and B valves and once every 9 moaths fcr Category C valves.
It is the staff's position that the code is inconsistent and that Category C valves s; _uld be 4
tested on the same schedule as Category A and P.
valves. The licensee has agreed to modify hu rate on cold shutdown to read, "In the case cf frequent cold shutdowns, valve testing need not be performed more of ten than once every three months for Category A, B, and C valves."
- 5. Changes to the Technical Specifications In a November 1976 letter tc the licensee, the NRC provided an attachment entitled "NRC Staff Guidelines
~ for Excluding Exercising (Cycling) T @ af Certain Valves During Plant Operation." The attachment stated that when one train of a redundant system such as in the Emergency Core Cooling System (ECCS) is inoperable, ,
nonredundant valves in the remaining train should not be cycled since their failure would cause a loss of total system function. For example, during power 4
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operation in some plants, tnere are stated minimum -
requirements for systems which allow certain limiting conditions for operation to exist at any one time and ,
if the system is not restored to meet the requirements within the time period specified in a plant's Technical Specifications (T.S.), the reactor is required to be put in some other mode. Furthermore, prior to initiating repairs, all valves and interlocks in the system that provide a duplicate function are required to be tested to demonstrate operability immediately and periodically thereafter during power operation. For such plants this situaticn could be contrary to the NRC guideline as stated in the document mentioned above.
The licensee has agreed to review the plant's Technical Specifications and to consider the need to propose Technical Specification changes which would have the effect of precluding such testing.
After making this review, if the licensee determines that the T.S. should be changed because the guidelines are applicable, the licensee will submit to the NRC, in .
conjunction with the proposed T.S. change, the inoperable condition for each system that is affected which demonstrates that the valve's failure would cause -
a loss of system function or if the licensee determines that'the T.S. should not be changed because the guidelines are not applicable or cannot be followed, the licensee will submit the reasons that led to their determination for each potentially affected section of the T.S.
- 6. Safety Related Valves This reviu was limited to safety-related valves.
Safety-related valves are defined as those valves that are needed te mitigate the consequences of an accident and/or to shut down the reactor and to maintain the reactor in a shutdown condition. Valves in this category would typically include certain ASME'Ccde Class 1, 2 and 3 valves and could include some non-code Class valves.
It should be noted that the licensee may have included ,
non-safety related valves in their Inservice Test Program as a decision on the licensee's part to expand the scope of their program. -
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A. Safety Injection (SI) System
- 1. Category C Valves
- a. Relief Request ,
Specific relief is requested from quarterly full stt-oke exercising the following valves:
2-SI-00'8 HPSI header 'A' check valve 2-SI-009 HPSI-A to loop 28 check 2-SI-010 HPSI-A to loop 2A check 2-SI-011 HPSI-A to loop 1B check 2-SI-012 HPSI-A to loop 1A check 2-SI-113 HPSI-B to loop 1A check 2-SI-123 HPSI-B to loop IB check 2-SI-133 HPSI-B to loop 2A check 2-SI-143 HPSI-B to loop 2B check 2-SI-405 HPSI pump C discharge check 2-SI-414 HPSI pump B discharge check 2-SI-127 HPSI pump A discharge check Code Requirement Refer to valve testing paragraph A.2.
Licensee's Basis for Requesting Relief Full stroke exercising these valves by establishing full flow through the valves can only be accomplished during refueling outages since the only full flow path'is into the reactor coolant system.
Evaluation We agree with the licensee's basis, and therefore feel relief hould be granted from the exercising requirements of Section XI for the following valves:
2-SI-008 HPSI header 'A' check alve 2-SI-009 HPSI-A to loop 2B check 2-51-010 HPSI-A to loop 2A check 2-51-011 HPSI.-A to loop 18 check 2-SI-012 HPSI-A to loop 1A check l
2-SI-113 HPSI-B to loop 1A check 2-SI-123 HPSI B to loop 18 check 2-SI-133 HPSI-B to loop 2A check 11 t
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.2-SI-143 HPSI-B to loop 2B check -
, 2-SI-405' HPSI pump C discharge check 2-SI-414 HPSI pump B discharge check ,
2-SI-427 HPSI pump A discharge check The licensee has demonstrated that full stroke
.- exercising these valves during power operation cannot be accomplished since the HPSI pumps discharge pressure (~1200 psi) is insufficient to pump into the RCS (~2255 psi), the only full flowpath. During cold shutdown overpressizuration of the RCS could result if a full flow / full stroke test of these valves was performed. All above mentioned valves will be partial stroke exercised quarterly and full stroke exercised during refueling outages.
- b. Relief Request Specific relief is requested from quarterly and cold shutdown full stroke exercising 2-SI-401 and 2-SI-410, HPSI pump suction check valves. ,
Code Requirement I Refer to valve testing paragraph A.2.
Licensee's Basis for Requetting Relief ,
Full stroke exercising these valves requires running two HPSI pumps at full flow through each check valve and this can only be accomplished i during refueling outages. During power operation the HPSI pumps do not have sufficient discharge p(~ressure 2255 psi).(~1200 During psi) cold to pump intodischarging shutdowns the RCS two HPSI pumps into the RCS could cause an overpressurization of the RCS.
Evaluation We agree with the licensee's basis and therefore l feel relief should be granted from quarterly and
- cold shutdown exercising Category C check valves ,
2-SI-401 and 2-SI-410. These check valves will be partial stroke exercised quarterly and full stroke r %
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exercised during refueling outages. The only existing flow path available to establish full flow through these valves is into the RCS and this is not possible during power operation due to the relatively low discharge pressure of the HPSI pumps. During cold shutdown discharging the quantity of water required for full stroke exercising these valves into the RCS could cause overpressurization of the RCS. These valves will be full stroke exercised during refueling outages when the reactor head is removed and the refueling pool can provide the necessary volume to accomodate the flow required to full stroke exercise these check valves.
- c. Relief Request Specific relief is requested from full stroke exercising Category C check valves 2-SI-215, 225, i
235, and 245, Safety Injection Tanks (SIT's) outlet check valves.
Code Requirement Refer.to valve testing paragraph A.2. t Licensee's Basis for Requesting Relief Valves cannot be full stroke exercised during reactor operation, cold shutdown or refueling since no flow path exists which can accept full flow. Valves cannot be part-stroke tested during reactor operation since failure of the test line isolation valve to shut would result in loss of safety injection tank level and consequent plant shutdown; further, if this valve fails to reseat, only single valve isolation would exist between the reactor coolant system and the low pressure safety injection tank.
Evaluation The licensee has shown that full stroke exercising
, valves 2-SI-215, 2-SI-225, 2-SI-235, and 2-SI-245 cannot be accomplished during power operation since the only flowpath is into the RCS which is at a greater pressure than the SITS. During cold shutdowns the full stroking of these valves could cause a low temperature overpressurization of the i
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l RCS. The utility has proposed a partial stroke ~
exercise of these valves on a cold shutdown frequency which is satisfactory for demonstrating .
valve disk movement. However, we feel the utility has not fully investigated the alternate means for full stroke exercising these valves. Therefore we recommend that relief not be granted from the exercising requirements of Section XI for these valves.
B. Containment Soray (CS) System
- 1. Category C Valves
- a. Relief Request Specific relief is requested from quarterly exercising Category C check valves 2-CS-5A and 2-CS-5B, containment spray header check valves.
Code Requirement Refer to valve testing paragraph A.2.
Licensee's Basis for Requesting Relief -
Valve operation cannot be verified during reactor operation since the valves are inaccessible during operation. To verify movement of these valves, air must be admitted upstream and valve motion monitored audibly. Water cannot be used for this l test since containment wetting would result.
As an alternate test these valves will be full stroke exercised during extended (greater than three weeks) cold shutdowns and refueling outages.
Evaluation We agree with the licensee's basis and therefore feel relief should be granted from the quarterly exercising requirements of Section XI for valves 2-CS-5A and 2-CS-5B. The licensee has l demonstrated that exercising these valves ,
quarterly cannot be accomplished since the valves are in a location inaccessible during power operation. These valves cannot be flow tested -
with water as this would spray contaminated borated water on the components in the reactor building, soaking lagging, spraying electrical 14
r components and motors, etc. This would require a large decontamination effort and place undue hardships on the utility. An air test can be performed by admitting air into a test connection and listening for the valve disc to slam open.
This test can only be performed during extended (greater than three weeks) cold shutdowns and refueling outages when only one shutdown heat exchanger is required for decay heat removal. We feel this alternate test frequency is sufficient to demonstrate proper valve operation.
- b. Relief Request Specific relief is requested from quarterly and cold shutdown full stroke exercising 2-CS-14A and '
2-CS-14B, refueling water storage tank outlet check valves.
Code Requirement Refer te valve testing paragraph A.2.
Licens'.e's Basis for Requesting Relief Full stroke exercising these valves requires discharging an HPSI pump and an LPSI pump into the l RCS. This cannot be accomplished during power '
operation since these pumps do not develop enough.
discharge pressure to pump into the RCS. During cold shutdown the HPSI pumps cannot he discharged into the RCS since a plant overpressurization could occur. An alternate test frequency of partial stroke exercising quarterly and full stroke exercising during refueling outages is proposed.
Evaluation We agree with the licensee's basis and therefore feel relief should be granted from quarterly and '
cold shutdown full stroke exercising Category C check valves 2-CS-14A and 2-CS-148. The only
, existing flowpath for full stroke exerci-ing these valves requires injection of design SI flow into the RCS. This cannot be accomplis' . during power operation since the SI pumps do ne. at ) duce enough discharge pressure to pump into the %S when at power. During cold shutdown an overpressurization of the RCS could occur if this test is conducted.
These valves will be partial stroke exercised quarterly and full stroke exercised during refueling outages.
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- c. Relief Request -
Specific relief is requested from full stroke .
exercising 2-CS-15A and 2-CS-158, containment sump outlet check valves.
Code Requirement
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Refer to valve testing paragraph A.2.
Licensee's Basis for Requesting Relief Valves cannot be full stroke exercised without
- filling containment to design post-accident water depth.
Valve will be part stroke exercised quarterly. No full stroke exercising is proposed.
Evaluation The licensee has demonstrated that utilizing flow .
to exercise check valves 2-CS-15A and 2-CS-15B, containment sump outlet check valves, would require flooding the containment to post-accident -
water level resulting in damage to electrical f components, lagging and other equipment and components in containment requiring extensive radioactive clean-up operations. The utility will partial stroke exercise these valves quarterly.
However, we feel the utility has not fully investigated the alternate methods of full stroke exercising these valves such as disassembly of the valve for manual valve operation. Therefore, we t feel relief should not be granted from the exercising requirements for these valves unless the utility has shown all alternate means are also impractical.
C. Reactor Building Closed Cooling Water (RB) System
- 1. Category'A Valves
- a. ~ Relief Request ,
Specific relief is requested from quarterly
-exercising 2-RB-30.1~A and B and 2-RB-37.2 A and -
B, RBCCW to and'from non-essential loads ~ in containment.
Code Requirement Refer to valve testing paragraph A.2.
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. Licensee's Basis for Requesting Relief Shutting these valves during power operation would isolate cooling water to the reactor coolant pump (RCP) thermal barrier coolers, RCP lube oil coolers, control element drive motor (CEDM) coolers and other equipment inside containment.
Cooling water to these components is required during power operation. An alternate test frequency of exercising these valves during cold shutdowns when all RCP's are not operating is proposed.
- Evaluation g We agree with the licensee's basis and therefore feel relief should be granted from the exercising requirement of Section XI for Category A valves 2-RB-30.1 A and B and 2-RB-37.2 A and B.
Exercising these valves during power operation would isolate cooling water to the RCP lube oil coolers and pump failure would soon follow. The RCP's require cooling water any time they are running, therefore the only practical time to exercise these valves is during cold shutdowns and refueling outages when all RCP's are not '
operating. The staff feels this alternate test frequency is sufficient to demonstrate proper valve operation and would not significantly reduce the level of plant safety.
D. Containment Isolation System
- 1. Category A and A/E Valves
- a. Relief Request Specific relief is requested from quarterly exercising 2-CH-505, 2-CH-506, and 2-CH-198, Reactor Coolant Pump (RCP) seals controlled leakoff valves.
Code Requirement 4
Refer to valve testing paragraph A.2.
. Licensee's Basis for Requesting Relief .
Shutting these valves during power operation would isolate the controlled lea ~Koff water from the RCP seals, causing rapid deterioration of the seals 17 L
and ultimately requiring reactor shutdown for seal
- repair. An alternate test of exercising these valves during cold shutdowns when the RCPs are not .
running is proposed.
Evaluati on We agree with the licensee's basis and therefore feel relief should be granted from the quarterly exercising requirements of Section XI for Category
. A valves 2-CH-505, ?-CH-506, and 2-CH-198. The licensee has demonstrated that shutting these valves-during power operation would cause failure of the RCP . seals and damage to the RCPs could result. Shutting these valves would stop the controlled leakoff which cools'and lubricates the pump 's eal s. Without this' leakoff the seals would shut down for RCP seal repairs. Therefore we feel
- that the proposed alternate test of full stroke
- exercising these valves during cold shutdowns and refueling outages when all RCPs are stopped is sufficient to demonstrate proper valve operability. ,
- b. Relief Request
- Specific relief is requested.from the exercising requirements of Section XI for valves 2-RW-232, 2-RW-21, 2-RW-154, and 2-RW-63. Refueling water i purification containment isolation valves.
h Code Requirement Refer to valve testing paragraph A.2.
Licensee S Basis for Requesting Relief During power operation these valves are locked shut and are not required to open for an accident.
Evaluation-We agree with the licensee's basis, and therefore j feel relief _should be granted for Category A/E valves 2-RW-232, 2-RW-21, 2-RW-154, and 2-RW-63 *
-i from the requirements of Sect'-a XI. These valves ,
are- in their safety related pos.31on and are not I required to open or close to mitigate-the .
consequences of an accident or safely shut down the plant. .Therefore, the operability of these -
valves'is-inconsequential with regard to the safety function which they perform. . We conclude that the quarterly stroke and stroke time measurements are meaningless for passive valves.
18 t
r , -. , . ~ = , - - , . , , ,r .
, .- 4 -. -
- c. Relief Request
, Specific relief is requested from the exercising requirements of Section XI for valves 2-AC-4, 2-AC-5, ?-AC-6, and 2-AC-7, purge air inlet and discharge containment isolation valves.
Code Requirement Refer to valve testing paragraph A.2.
Licensee's Basis for Requesting Relief During power operation these valves are in the position required to perform their safety related function. These valves are required by technical .
Specifications to remain closed and be disabled closed during power operation.
Evaluation
~
We agree with the licensee's basis, and therefore feel' relief should be granted for Category A valves 2-AC-4, A-AC-5, 2-AC-6, and 2-AC-7 from the requirements of Section XI. These valves are in their. safety related position and are not required to open or close to mitigate the consequences of an accident or safely shut down the plant.
Therefore, the operability of these valves are inconsequential with regard to the safety function which they perform. We conclude that the quarterly stroke and stroke time measurements are meaningless for passive valves,
- d. Relief Request Specific relief is requested from the exercising requirements of Section XI for valves 2-SA-19, station air to containment isolation valve.
Code Requirement Refer to valve testing paragraph A.2.
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Licensee's Basis for Requesting Relief This valve is shut during power operation and is not required to open on any accident. This valve's only safety related function is to maintain its leak-tight integrity.
19
Ev luation - 1 We agree with the licensee's basis, and therefore ,
feel relief should be granted for Category A valve 2-SA-19 from the requirements of Section XI. This valve is in the safety related position and is not required to open or close to mitigate the consequences of an accident or safely shut down the plant. Therefore, the operability of this valve is inconsequential with regard to the safety function which it performs. We conclude that the quarterly stroke and stroke time measurements are meaningless for passive valves.
E. All Systems ~
- 1. Category A and B Valves
- a. Relief Request Specific relief is requested from the increased schedule of testing and/or the declaring of a ,
valve out of service as required by Section XI IWV-3410-(c)-(3) and IWV-3410 (g),
Code Requirement IWV-3410-(c) (3) If an increase in stroke time of 25% or more from the previous test for valves with stroke times greater than ten seconds or 50% or more for valves with stroke times less than or equal to ten seconds is' observed, test frequency
.shall be increased to once each month until corrective action is taken, at which time the original test frequency shall be resumed. In any case, any abnormality or erratic action shall be reported.
IWV-3410 (g) If a valve fails to exhibit the required change of valve stem or' disk position by this testing, corrective action shall be initiated immediately. If the condition is not, or cannot be corrected within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, the valve shali be declared inoperative. When correction is required ,
as a result of tests made during cold shutdown, the condition shall be corrected before startup.
A retest showing acceptable operation shall be run -
following any required corrective: action before ,
the valve is returned to service.
, 20 e
Licensee's Basis for Requesting Relief It is the position of NNECO that the operating '
status of a valve including certain deviations from the required stroke time is best determined by plant management af ter an Engineering and Operations review of test data NNECO therefore requests relief from those requirements of IWV-3410 (c) (3) and IWV-3410 (g) which require an increased schedule of testing and/or the declaring of a valve out of service.
Evaluation We feel the licensee has not provided sufficient technical information to provide a basis for granting relief from the requirements of Section XI IWV-3410(c)(3) for all valves listed in their IST program. However, we do feel relief should be gr anted from the requirements of IWV-3410(c)(3) for valves with specified testing
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frequencies of cold shutdowns and refueling outages. The licensee has provided sufficient technical information to justify testing at these frequencies and an increased frequency of monthly would require testing during power operation which has already been demonstrated as impractical.
IWV-3410(g) requires that a valve declared inoperative as a result of cold shutdown testing, be repaired prior to startup of the plant. We feel the plant technical specifications address this condition and have allowed specific limiting conditions for . operation and permit plant operation with sections of safety systems out of service for specific time periods. Therefore we feel relief should be granted from the requirements of IWV-3410(g).
- 2. Category C Valves
- a. Relief Request
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Specific relief is requested from corrective action requirements of IWV-3520(c) of Section XI.
- Code Requirement Corrective Action. If a check valve fails to exhibit the required change of disk position by
, this testing, corrective action shall be initiated imediately. If the condition is not, or can not be corrected within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, the check valve 21 L 2
shall be declared inoperative. When corrective action is required as a result of tests made
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during cold shutdown, the condition shall be corrected before startup. A retest showing acceptable performance shall be run following any required corrective action before the valve is returned to service.
Licensee's Basis for Requ2 sting Relief IWV-3520(c) Check Valve Tests - Corrective
!. Action - requires that a valve be declared inoperative if test requirements cannot be verified wihin 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> of test performance.
NNECO intends to implement this paragraph by stating corrective action in the specific valve test procedures. Unsatisfactory test results may or may not lead to an " inoperative" status, depending upon~an engineering evaluation.and disposition of test data by plant management.
Evaluation We feel the licensee has not provided sufficier ;
technical information to provide a basis for i granting relief from the requirements of ,
l IWV-3520(c). We feel that .if the check valve l fails to exhibit the required change of disc position then corrective action must be initiated and/or the valve declared out of service.
l However, check valves that fail to exhibit the l required change of disc position during cold l
' shutdown or refueling testing need not be repaired prior to plant startup as specified by this section of the Code (refer to Section E.1.a. of this report).
l b. Relief Request
( Specific relief is requested from the relief valve l testing specification referenced in the applicable edition and addenda of Section XI.
Code Requirement l
Test Procedure: Safety valves and relief valves set pcints shall be tested in accordance with ASME PTC 25.2-1966. Bench testing with suitable
- L i
hydraulic or pneumatic equipment or testing in place with hydraulic or pneumatic assist equipment may be used as acceptable method permitted under l PTC 25.2-1966.
22
,m
Licensee's Basis for Requesting Relief Relief valve set points will be tested in accordance with ASME PTC 25.3-1976 in lieu of PTC 25.2-1966 as referenced in the Summer 1975 Addenda, as the earlier version has been revised -
and superseded.
Evaluation The licensee's IST program as submitted and our subsequent review of that program is based upon the 1974 edition through Summer 1975 addenda of Section XI of the ASME Code. This code specifically identifies ASME 25.2-1966 as the applicable reference for safety and relief valve testing. We feel it is the licensee's responsibility to demonstrate that the ASME PTC 25.3-1976 reference meets the intent in all respects of the reference specified.
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. ,_ _w , _ . .. . . -
L l IV. ATTACHMENT I -
l l A. Appendix'J Exemption Requests .
- 1. The NRC is presently reviewing the Millstone Unit 2, Appendix J exemption request from leak testing the following valves in accordance with the requirements of Append.ix J.
RW -
232, 21, 154, 63 SI -
'709 MS -
191 A-& B MS -
220 A & B AC -
4,5,6,7
- EB - 91, 92, 99, 100 SSP. -
16.1 and 16.2 LRR -
61.1,-43.1, 43.2 SA -
19 SI- -
312 L SI -
463 i CH. -
089 RC - 001, 002, 003 l PMW - 43 l CH -
505, 506, 198 '
RB -
30.1 A & B RB -
37.2 A & B -
If this exemption is authorized, the above mentioned valves
- will be exempt from the leak testing require ents of Appendix J and Section XI. If this exemption is, not '
authorized, plant modifications 'will be required to ensure leak testing will be in accordance with the requirements of
- Appendix J and Section XI._
l i
\ -
9 j:
24
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V. ATTACHMENT II
, The following are Category A, B, and C valves that meet the requii-aments of the ASME Code Section XI and are not full stroke -
exert. sed every three months during plant operation. These valves are specifically identified by the owner and are full stroke exercised during cold shutdowns and refueling outages. EG&G has reviewed all valves in this attachment and agrees with the licensee that testing these valves during power operation is not possible due to the valve type and location, or because this action would place the plant in an unsafe condition.
power operation. - We feel these valves should not be' exercised during A. Chemical and Volume Control (CH) System
- 1. - Normally closed Category C check valves 2-CH-177, boric acid pump emergency supply to charging pump suction and 2-CH-190, boric acid tank gravity feed check valve, cannot be exercised during power operation since opening these valves would allow concentrated boric acid to flow directly to the charging pump _ suction header resulting in a rapid reduction in reactor power. These valves will be full stroke exercised during cold shutdowns and refueling outages.
- 2. Normally open Category B valves 2-CH-501, volume control tank outlet, cannot be exercised during power operation since shutting this valve would interrupt the flow of charging water resulting in thermal. transients on the regenerative heat exchanger.- Utilizing an alternate suction
- ~
path for the charging pumps would inject higher concentration borated water resulting in a Reactor Coolant System boron concentration transient. Valve 2-CH-501 will be full stroke exercised during cold shutdowns and refueling outages.
- 3. Normally open Category B valve 2-CH-515, letdown safety injection actuation signal isolation valve, cannot be ;
exercised during power operation sin _ce shutting this valve l would interrupt letdown flow through the regenerative heat !
exchanger resulting.in thermal transients on this !
component. This component has a limited number of design i thermal transients. Valve 2-CH-515 will be full stroke-exercised during cold shutdowns 'and refueling outages.
- 4. Normally closed Category B valve 2-CH-517, Pressurizer auxiliary spray valve,-cannot be exercised during power 4 operation since opening this valve sprays the pressurizer
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steam bubble thus-reducing RCS pressure. Should this valve fail, open RCS pressure control would be lost and the plant must be shut.down. These valves will be full stroke exercised during cold shutdowns and refueling outages.
25 I
m- ]
- 5. Normally open Category B valves 2-CH-518 and 2-CH-519, -
normal charging to loops lA and 2A isolation valves, cannot be exercised during power operation. Should one of these .
valves fail in the closed position the plant would be placed in an unsafe condition. These valves are required to be open for high pressure injection during a small break .
accident. These values will be full stroke exercised during cold shutdowns and refueling outages.
- 1. Normally open Category B/C testable check valves 2-FW-5A and B, feedwater to #1 and #2 Steam Generators check valves, cannot be exercised during power opeation since shutting these valves would require stopping feed flow to the corresponding steam generator with consequent plant shutdown. Valves 2-FW-5A and B will be full stroke exercised during cold shutdowns and refueling outages.
- 2. Normally closed Category C valves 2-FW-7 and 2-FW-8A and B, '
steam generator auxiliary feed pump discharge check valves, cannot be exercised during power operation since relatively '
cold water would be injected into the steam generators (SG's) resulting in large thermal transients on the feed ring. These valves will be full stroke exercised during -
cold shutdowns and refueling outages.
- 3. Normally closed Category C valves 2-FW-12 A and B, auxiliary feed to steam generators A and B check valves, cannot be exercised during power operation since relatively cold water would be injected into the SGs resulting in large thermal transients on the feed ring. These valves will be full stroke exercised during cold shutdowns and refueling outages C. Safety Injection (SI) System '
- l. Normally closed Category C valves 2-SI-114, 124, 134, and 144, LPSI to loop check valves, cannot be exercised during power operation since the LPSI pumps cannot develop enough discharge pressure to overcome the downstream pressure on these valves produced by the Safety Injection Tanks (SITS).
These valves will be full stroke exercised during cold shutdowns and refueling outages.
- 2. Normally closed Category C check valves 2-SI-217, 2-SI-227, '
2-SI-237 and 2-SI-247, HPSI-LPSI discharge to loops, cannot be exercised during power operation since the large .
temperature difference between the safety injection system water and the reactor coolant system (approximately 4000F) would cause undue thermal stress of the safety injection nozzles. These valves will be full stroke exercised during cold shutdowns and refueling outages.
26 L. ___ __
- 3. Normally closed Category C check valves 2-SI-434 and 2-SI-446, LPSI pumps discharge check valves, cannot be exercised during power operation since the pumps cannot overcome SIT pressure downstream of the 2-SI-706 series valves. Realignment of the system to allow flow via the test line would render the LPSI system inoperable. Valves 2-51-434 and 2-SI-446 will-be full stroke exercised during cold shutdowns and refueling outages.
- 4. Normally closed Category A valve 2-SI-651 and Category B valve.2-SI-652, shutdown cooling from RCS isolation valves, cannot be exercised-during power operation since these valves are locked closed when the RCS pressure is greater than 300 psig. Opening these valves during power operation would require violation of plant interlocks and would over-pressurize the shutdown cooling system. These valves will be full stroke exercised during' cold shutdowns and refueling outages.
- 5. Normally open Category B valves 2-SI-659 and 2-SI-660, CS/SI pump minimum flow recirculation stop valves, cannot be exercised during power operation since these valves are-required by Technical Specifications to be open and ,
de-energized during power operation to provide a recirculation path for the containment spray pumps and the safety injection pumps upon pump starting. These valves do not receive a safety injection actuation signal. Valves 2-SI-659 and 2-SI-660 will be full stroke exercised during cold shutdowns and refueling outages.
- 6. Normally closed Category C valves 2-SI-706, A, B, C, & D, SI header to loop check valves, cannot be full stroke exercised during power operation. Full stroking these valves requires full LPSI flow into the loops and this can only be accomplished during cold shutdown. These valves will be partial stroke exercised quarterly and full stroke exercised during cold shutdowns and refueling outages.
D. Containment Spray (CS) System
- 1. Normally open Category B valves 2-CS-13.1 A & B, refueling water storage tank (RWST) outlet valves, cannot be exercised during power operation since shutting these valves would
, isolate the RWST from the Safety Injection pumps. Failure of one of these valves in the closed position would require the plant to be shut down.- These valves will be full stroke exercised during cold shutdowns and refueling outages.
27
E. Main Steam (MS) System -
- 1. Normally open Category B valves 2-MS-64 A and B and 2-MS-65 ,
A and B, Main Steam Isolation Valves (MSIVs) and MSIV Bypass valves, cannot be exercised during power operation since shutting these valves would cause a turbine trip and possibly result in a reator trip. These valves will be full r
stroke exercised during cold shutdowns and refueling outages.
- 2. Normally , closed Category B valves 2-MS-190 A and B, SG atmospheric dump valves, cannot be exercised during power operation since opening these valves would cause a large steam flow transient and isolation of the valves for exercising would reduce plant ability to withstand a turbine trip. These valves will be full stroke exercised during cold shutdowns and refueling outages.
F. Containment Isolation Systems
- 1. Normally open Category A valves 2-CH-089 and 2-CH-516, letdown to purification demineralizers, cannot be exercised during power operation since shutting these valves would '
interrupt letdown flow through the regenerative heat exchanger resulting in thermal transients on this -
component. This component has a limited number of design ,
thermal transients. These valves will be full stroke exercised during cold shutdowns and refueling outages.
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e
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, VI.- ATTACHMENT III
,_ The P&ID's listed below were used during-the' course of this review.
1.. INSERVICE INSPECTION PROGRAM Drawings 25203-26126 sheets-l through 11 for the systems'11sted below:
Safety-Injection, Containment Spray sh.3 Chemical and Volume Control sh.8&9 Main Steam sh.2 Reactor Coolant sh.ll Consensate and Fecdwater sh.4 Reactor Building Closed Cooling Water sh.6 Chilled Water for Switchgear Room sh.10 Service Waier sh.7 Service Water to Chilled Water sh.5 Spent Fuel Pool Cooling & Cleanup sh.1
- 2. Additional P&ID's used:
Containment & Enclosure Building Ventilation P& ids.
Drawing Numbers: 25203-26028 sh.1 rev 1.
25203-26028 sh.2 rev 1.
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s e 29 h.- __
VII. ATTACHMENT-IV -
A. The following are valves that are never full stroke exercised or ,
that have a testing interval greater than each refueling outage:
- 1. 2-CS-15 A&B Containment Sump Recirculation Checks
- 2. 2-SI-215, 225, 235, 245 STT Outlet Checks B. The following is a listing of relief requests where insufficient information was provided and relief is not recommended.
Puno Testing Program .
- 1. A.3 Valve Testing Program
- 1. A.1.c
- 2. B.1.c
- 3. E.1.a
- 4. E.2.a
- 5. E.2.b '
6 S
5 30
._