ML20151C446
| ML20151C446 | |
| Person / Time | |
|---|---|
| Site: | Comanche Peak  |
| Issue date: | 04/08/1988 |
| From: | Counsil W TEXAS UTILITIES ELECTRIC CO. (TU ELECTRIC) |
| To: | NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM) |
| References | |
| IEB-85-003, IEB-85-3, TXX-88381, NUDOCS 8804130003 | |
| Download: ML20151C446 (5) | |
Text
_ _ __ _ _. _ __
.4
-==
- """ 7 Log # TXX-88381
~.~-
Fi1e # 10119 1UELECTRIC f( llW 6C 936s$rni U. S. Nuclear Regulatory Commission Attn:
Document Control Desk Washington, D.C.
20555
SUBJECT:
COMANCHE PEAK STEAM ELECTRIC STATION (CPSES)
DOCKET NOS. 50-445 AND 50-446 NRC REQUEST FOR ADDITIONAL INFORMATION -
IE BULLETIN 85-03 REF:
1)
IE Bulletin No. 85-03: Motor-0perated Valve Common Mode Failures During Plant Transients Due to Improper Switch Settings, dated November 15, 1985.
2)
TUGC0 letter TXX-4781 from W. G. Counsil to R. D. Martin (Region IV), dated April 30, 1986.
3)
TUGC0 letter TXX-4901 from W. G. Counsil to R. D. Martin (Region IV), dated July 14, 1986.
4)
Request for Additional Information - IE Bulletin 85-03 from C. I. Grimes (Office of Special Projects) to W. G. Counsil, dated March 3,1988.
Gentlemen:
Reference (4), requested TV Electric to provide additional information to our response to Reference (1), Item (e), which required a written report in response to the bulletin issues.
The following information is given in response to your Request for Additional Information - IE Bulletin 85-03 "Motor Operated Valve Common Mode Failures During Plant Transients Due to improper Switch Settings."
Very truly yours, fN#t W. G. Counsil DAR/grr c - Mr. R. D. Martin, Region IV Resident inspectors, CPSES (3)
$$0NDO 400 North Olive Streft LB81 Dallas. Texas 73201
4 TXX-88381 April 8, 1988 UNITED STATES OF AMERICA NUCLEAR REGULATORY C0tti!SSION In the Matter of Texas Utilities Electric Company
)
Docket Nos. 50-445 50-446 (Comanche Peak Steam Electric Station, Units 1 & 2)
AFFIDAVIT W. G. Counsil being duly sworn, hereby deposes and says that he is Executive Vice President, Nuclear Engineering and Operations of TV Electric, e
the Applicant herein; that he_is duly authorized to sign and file with the Nuclear Regulatory Commission this response to Request for Additional
. information - IE Bulletin 85-03 that he is familiar with the content thereof; and that the matters set forth therein are true and correct to the best of his knowledge, information and belief.
(17A M W.' G. Co>insiT Executive Vice President, Nuclear Engineering and Operations STATE OF TEXAS COUNTY OF DALLAS Subscribed and sworn to before me, u Notary Public in and for c2c4 s on this 57 at, day of 6 d 6
, 1988.
I s
bW W
Notary Putrlic My commission expires: 3 - / A - 90
Attachment to TXX-88381 April 8, 1988 Page 1 of 3 Item 1 Has water hammer due to valve closure been considered in the determination of pressure differentials?
If not, explain.
CPSES Response Transient increases in differential pressures across valve seats due to valve closure (water hammeri were not included in the maximum operating differential pressures reported by CPSES in the July 14, 1986 letter TXX-4901 (Ref. 3) to the NRC, nor is it now considered necessary that these transient pressure increases be included.
At CPSES, representative Motor Operated Valves (MOVs) will be stroke tested while subjected to as near the maximum o)erating differential pressure (dP) and fluid flow conditions as is practica)le to achieve.
The actual dP against which a valve is stroked will therefore be the sum of the applied steady-state dP plus the resulting transient dP rise.
In-line pressure gages will be used to measure the steady-state dP after the valve is closed.
Special MOV test equipment will be used to measure the stem thrust (TDPT) required to close against the sum of steady-state dP plus the transient dP rise.
If the tested steady-state dP value (DPT) is less than the calculated maximum operating steady-state dP value (DPR), then the stem thrust (TDPR) to close against the greater steady-state dP plus the resulting transient dP rise will be calculated by straight line extrapolation: TDPR = TDPT (DPR/DPT).
The CPSES testing program may include testing of a small sample of valves at multiple steady-state dP values to obtain test data which is expected to substantiate the straight line extrapolation method. Alternatively, an analysis may be provided to substantiate the extrapolation method.
Testing will also be perforrad without differential pressure and fluid flow in order to determine the ster running" thrust (RT) needed simply to move the stem when there is no dP apsiied.
The minimum allowable sten thrust is the sum of RT plus TOPR.
Item 2 MOV HV-2452 is shown normally closed in the steam line from the steam generators to the auxiliary (Unit 1).feedwater turbine, in Zone C-5 of Drawing 2323-MI-0202 Revision CP-7 This M0V is not listed in Table 1 of TV Electric's May 14, 1986 response; however, it is included as HV-312 on Page 28 of the Westinghouse Owner's Group Report of March 1986.
Revise Table 1 to include this MOV, or justify its exclusion.
As required by action item a of the Bulletin, assume inadvertent equipment operations.
CPSES Response Valve HV-2452 is shown normally open in both revision (CP-7) and the current revision (CP-9) of drawing 2323-MI-202. A turbine overspeed signal causes this turbine trip and throttle valve to close under the motive force of a compressed spring.
The motor actuator is used to reset the valve to its normal latched open position.
Upstream of HV-2452 are two normally closed steam admitting air-operated valves HV-2452-1 and HV-2452-2.
These valves are safety-related and ensure a steam supply to the auxiliary feedwater pump turbine.
The plant safety analysis considers that during a design basis
1 Attachment to TXX-88381 April 8, 1988 Page 2 of 3 accident the single failure of tne turbine-driven auxiliary feedwater pump or inadvertent valve operation will not prevent the auxiliary feedwater system from performing its safety-related function.
The applicable station operating procedure required that valve HV-2452-1 and/or HV-2452-2, whichever is open, be closed before reopening HV-2452.
Consequently, valve HV-2452 is not considered to have a safety-related motor actuated function and is excluded from the list of motor operated valves addressed by IE Bulletin 85-03.
Item 3(a) l The proposed program for action items b, c and d of the Bulletin is incomplete.
Provide the following details as a minimum:
(a) commitment to a trsining program for setting switches, maintaining valve operators, using signature testing equipment and interpreting signatures; CPSES Response MOV activities including setting switches, maintaining valve operato s, using signature acquisition test equipment, and interpreting signatures will be performed by personnel who have first received adequate training to support the satisfactory performance of these tasks.
The training shall be performed and documented in accordance with site procedures.
Items 3(b) and 3(c)
The proposed program for action items b, c and d of the Bulletin is 4
incomplete.
Provide the following details as a minimum:
(b) description of a method possibly needed to extrapolate valve stem thrust measured at less than maximum differential pressure; (c) justification of a possible alternative to testing at maximum
[
differential pressure at the plant; and l
CPSES Response Each test with differential pressure and fluid flow ("dP test") shall be conducted such that the tested differential pressure (DPT) across the valv; is as near as practicable to the calculated maximum operating dP within the plant I
design basis, the "required" dP (DPR).
The value of DPT is expected to be equal to or greater than the value of DPR unless:
(1) the system, configured to simulate the most severe design basis condition and operated at its maximum capability, cannot achieve the conservatively calculated value of DPR, or (2) the system is configured in a manner other than that assumed when determining DPR (for example, DPR may not be achieved in order to maintain a minimum recirculation flow for the protection of a pump).
DPT shall be determined by measuring the upstream and downstream pressures with calibrated pressure gauges and adjusting the indicated pressures to account for the differences in elevation between the pressure gauges and the valve seat.
l
Attachment to TXX-88381 April 8, 1988 Page 3 of 3 If DPT is less than DPR for reason (1) above, then the switch setting may be considered correct if the resulting stem thrust is not outside the acceptable range determined using DPT in place of DDR.
If DPT is less than DPR for reason (2) above, the switch setting and resulting stem thrust adequacy shall be justified as being adequate to ensure MOV operability when the valve is subjected to DPR. This is accomplished by the straight line extrapolation method described in the response to item 1.
CPSES will test at least one valve from each group of similar valves under two conditions:
(1) no differential pressure and no fluid flow, and (2) differential pressure and fluid flow.
The stem running thrust, RT, needed simply to move the valve stem when there is no dP applied is determined from the tests without dP.
The maximum stem thrust needed to properly stroke the valve against dP and fluid flow is then compared with the value of RT to determine the stem thrust "TDPT" required to overcome the effects of the applied test dP, DPT.
The value of stem thrust "TDPR" required to overcome the effects of a "required" dP, DPR, is determined by linear extrapolation to be TDPR = TDPT (DPR/DPT).
Therefore, the minimum stem thrust needed for stroking this valve against DPR is the sum of RT plus TDPR.
Other valves from each group of similar valves need only be tested to detennine the values of RT for each of these other valves.
The minimum stem thrust required for each of these other valves is then the sum RT plus TDPR.
Item 3(d)
The proposed program for action items b, c and d of the Bulletin is incomplete.
Provide the following details as a minimum:
(d) stroke testing when necessary to meet Bulletin requirements.
CPSES Response In addition to the stroke testing described in the above responses to Items 1, 3(b), and 3(c), stroke testing shall be conducted during the life of the plant to ensure that correct valve switch settings are maintained. Anoropriate stroke testing will be performed (taking into account applicable industry recommendations and experience) following maintenance activities which may effect stem thrusts, or to provide signatures to support periodic valve performance monitoring.
)
__