ML20042B811
| ML20042B811 | |
| Person / Time | |
|---|---|
| Site: | Fort Saint Vrain  |
| Issue date: | 03/11/1982 |
| From: | Lee O PUBLIC SERVICE CO. OF COLORADO |
| To: | Jay Collins NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| References | |
| REF-SSINS-6820 IEB-80-06, IEB-80-6, P-82054, NUDOCS 8203260174 | |
| Download: ML20042B811 (11) | |
Text
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UBLIC SERVICE CONFANY OF COLORADO N'
y;d?. ?j,h P.
O. BOX 840 OENVER.
COLORADO 80206 t1 arch 11, l982 0l 5
Q OSCAH H. LEE Fort St Vrain I
g Unit No. I fo 3
P-82054 8
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3[g@ LSilW/Y*
Mr. John T. Collins
~
Regional Administrator s
Region IV HAR I 81982 Office of Inspection and Enforcement
.)
Nuclear Regulatory Commission
~
611 Ryan Plaza Drive, Suite 1000 Arlington, Texas 76012 Docket No. 50-267
Subject:
IE Bulletin No. 80-06 Engineered Safety Feature (ESF) Reset Controls
Reference:
- 1) NRC letter from K.V. Seyfrit to C.K. Millen, G-80041, dtd 3/13/80
- 2) PSC letter from D. Warembourg to K.V. Seyfrit, P-80063, dtd 3/27/80
- 3) PSC letter fran 0.R. Lee to K.V. Seyfrit, P-81265, dtd 10/30/81
- 4) PSC letter from 0.R. Lee to J.T. Collins, P-82016, dtd 1/15/82
Dear Mr. Collins:
IE Bulletin No. 80-06 directed PSC to detennine whether any component of safety-related equipment actuated by the Fort St.
Vrain (FSV) Engineered Safety Features (ESFs) would return to its nonnal
- u. ode (resetting fran its actuated mode) following reset of the associated Actuation Signal (ESFAS), and by this action, compromise protective action supplied by the affected system.
As was stated in letter P-81265, and supported by transmittal of applicable FSAR pages, the steam generator steam / water dump system is 4
e
P-82054 Page 2 March 11, 1982 the only ESF System to receive electronic actuation signals which change the system operating condition from the " normal" mode to the actuated "eme rgency" mode by shutting down the affected loop and dumping the contents of the affected steam generator.
Consequently, only the steain/ water dump system needed to be addressed by the four Licensee Actions listed in IE Bulletin flo. 80-06.
In letter P-82016 PSC informed the f1RC of the completion of the review of the FSV steam / water dump system schematics and elementary
- drawings, in accordance with Licensee Action 1 of IE Bulletin 80-06.
The review determined that removal of the appropriate actuation signal from the steam / water dump system will not cause any actuated valve of the dumped loop to return automati M ly to its normal position from its actuated position.
Schematic analysis of the functional operation of each of these valves showed each valve characteristically requires one or more deliberately-initiated operator actions to reposition each valve to its nonnal mode of operation.
Letter P-82016 additionally advised
'he flRC of the functional test schedule planned at the FSV facility to verify that operation of the steam / water dump instrumentation and control system is consistent with the schematic review and analysis performed as Licensee Action 1.
(These functional verifica tion tests are identified in IE Bulletin 80-06 as Licensee Action 2.)
Licensee Action 2 has now been completed.
Since the attached analysis of these test results and previous operating events confirmed each valve of the steam / water dump system remains in its actuated mode following reset of the actuation signal, Licensee Action 3 of IE Bulletin 80-06 is not applicable.
(Licensee Action 3 required description of proposed corrective action, if any.)
Licensee Action 4 required a written report of the results of PSC review, listing of all devices with unacceptable reset response, and a schedule for corrective action.
All the requirements of Licensee Action 4 are satisfied by PSC letters P-81265, P-82016, and this letter P-82054.
Accordingly, PSC offers this letter as the final response to IE Bulletin flo. 80-06.
Very truly yours,
. bW
. Lee, Vice President Electric Production ORL/JRJ:pa Attachment
UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION In the Matter Public Service Company of Colorado
)
Docket No. 50-267 Fort St. Vrain Unit No. 1
)'
- 0. R. Lee, being duly sworn, hereby deposes and says that he is Vice President of Public Service Company of Colorado; that he is duly authorized to sign and file with the Nuclear Regulatory Commission the attached response to the IE Bulletin No. 80-06; that he is familiar with the content thereof; and that the matters set forth tnerein are true and correct to the best of his knowledge, informa-tion and belief.
-(
- 0. R. Lee Vice President CM+b
)
STATE OF
) ss COUNTY OF O'"
)
Subscribed and sworn to before me, a Notary Public in and for EN CM M on this
//Y day of JM
,1;82.
>~ h)G Notary Public My commission expires cu 7 /'/
, 19 8.
i P-82054 ATTACHMENT Page 1
SUMMARY
OF EVALUATION TESTS OF STEAM / WATER DUMP SYSTEM LOGIC, LOOP I AND LOOP II REF:
PPC-82-0346, Evaluation Test T-188, Loop I PPC-82-0347, Evaluation Test T-195, Loop II PPC-81-1000, Loop I Shutdown During PPS Feedwater Flow Surveillance Testing FSV-372-77, Discussion of Hot Restarts Performed at FSV on 12 Sept, 23 Sept, and 10 Oct, 1977 P_URPOSE I&E Bulletin No. 80-06 addressed the action of Engineered Safety Feature-actuated components upon removal (reset) of the signal (the Engineered Safety Feature Actuating Signal) which actuated the safety system. The objective of this test was to verify that the FSV steam / water dump system operates as described in the electrical drawings upon the initiation of a steam / water loop dump, and to veri fy that the ' actuated system components (which caused the steam / water loop dump, loop shutdown, and circulator shutdown actions) do not reset when the actuating signal is removed.
SYSTEM DESCRIPTION The steam / water dump system is provided to minimize the amount of water that can leak into the primaiy coola t as a result of a steam generator tube or subheader rupture.
This is accomplished by dumping the steam / water inventory of the ec on om i ze r-e v a po ra to r-su pe rhe a te r section of the leaking steam generator to the steam / water dump tank.
A schematic diagram of the Loop I portion of the system is shown in Figure 1.
Operation of the steam / water dump system logic to dump either Loop I or Loop II involves 24 remote-operated valves (12 valves per loop).
The valve name, equipment ID number, normal status, acutated status, and its response to an actuation signal removal is shown by Table 1.
Two other valves, actuated by the steam / water dump but not considered safety-related, were also tested and results are shown in Table 1.
The steam / water dump system is automatically actuated by one of three different actuation signals from the plant protective system (detection of high moisture in the primary coolant, high primary coolant pressure, or high pressure in the steam generator module penetrations),
or it can be manually actuated by an operator-initiated actuation signal.
The occurrence of a steam leak (high PCRV moisture) is normally detected by the primary coolant moisture monitors which identify the loop containing the leaking steam generator and alarm when the water concentration in the primary coolant reaches 100 volume parts per million (vpm).
When the water concentration reaches 500-1000 vpm
r P-82054 ATTACHMENT Page 2 (actual level depends on the leak rate), the leaking steam generator is automatically dumped to the steam / water dump tank.
Feedwater flow to, and helium circulation in, the affected loop is stopped simultaneously with the steam / water dump.
Primary coolant pressure sensors are used to back up the moisture monitors.
In the event that the redundant (2 of 3) primary coolant moisture monitors fail to operate, primary coo'. ant pressure actuates the steam / water dump system to minimize water inleakage to the reactor.
If the actual primary coolant pressure at the helium circulator outlet exceeds the expected primary coolant pressure, as programmed with load, by 7-1/2 percent (740 psig at full load), the contents of the steam generator of a preselected loop will be dumped to the steam / water dump tank.
The third actuation signal to the steam / water dump system is high pressure (800 psig) in a steam generator module penetration, indicating the rupture of a feedwater or main steam pipe. This actuation signal initiates a loop shutdown and steam / water dump.
A more detailed description of the steam / water dump Engineered Safeguard system can be found in FSAR Section 6.3.
TEST PROCEDURE The test procedure duplicated nomal operating conditions for the loop being tested as closely as possible.
The test sequence was as follows:
(a) ini tiate a steam / water dump of each loop and verify that the steam / water dump valves open; (b) verify that the loop shutdow a valves and circulator shut down valves close; (c) remove the actuation signal and note if any valve changes position; (d) verify that only operator action of the appropriate hand switch will restore the valve to its normal position.
The test was set up first to cause a loop steam / water dump based upon an actuation signal from high PCRV mois ture, next from s team generator penetration high pressure, and finally from high PCRV i
pressure. Both Loop I and Loop II were tested.
High PCRV moisture was simulated by tripping two low range and one high range moisture monitors in the loop to be tested.
High steam generator penetration pressure was simulated by setting two of the three Plant Protection System (PPS) switches to the test position. High PCRV pressure was simulated by setting two of three high reactor pressure switches to their test positions. The presence of the appropriate scram trip signal to tne reactor scram system from the high PCRV moisture and high PCRV pressure actuation signal simulation was also verified.
3ESULTS The results of checking Loop I and Loop II operation with each of the three actuation signals are summarized as follows:
P-82054 ATTACHMENT Page 3 (1) Upon receipt of the specific actuation signal the steam / water dump valves did open as requi red.
The loop shutdown valves and the 'cTr_culator shutdown valves did close as required.
(2) The actuation signal was removed and it was verified that none of the actuated valves changed position.
(3) The steam / water dump valves in Loop I and Loop II were closed by the operator action of taking the appropriate handswitch to its closed position. -The steam / water dump valves did go closed and the loop shutdown valves and circulator shutdown valves remained closed.
(4) Each loop shutdown and circulator shutdown valve reopened only after operator action returned its appropriate handswitch to the normal position and other operator-initiated actions were taken in accordance with normal System Operating Procedures.(SOP).
(5) Due to plant conditions, seven of the remote-controlled valves could not be functionally " stroked" (See Table 1 for valve identities).
DISCUSSION As is noted in Table 1, due to plant conditions, seven of the valves could not be directly stroked (e.g.,
tested for functional mechanical operation) when actuated with the appropriate electrical actuation signal.
As a consequence, three of the seven valves were verified for satisfactory operation on the basis of data obtained that showed satisfactory operation of a " companion" valve, i.e., one which has the same Control Relay Driver (XCR), which controls the same control I
rel ay, which in turn operates valve control circuit relay contacts l
common to both valves.
(Figure 2 illustrates the " companion" valve l
relationship.)
The three valves which were not " stroked", along with their
" companion" valves, are listed as follows:
1.
For Loop I "A"
helium circulator steam turbine outlet (block) valve (HV-2249), the "A"
helium circulator steam turbine inlet (speed control) valve (SV-2105) is the j
" companion" valve.
2.
For Loop II "D" helium circulator steam turbine inlet (speed control) valve (SV-2112), the "D" helium circulator steam turbine outlet (block) valve (HV-2252) is the " companion" valve.
P-82054 ATTACHtiENT Page 4 3.
For Loop 11 reheat inlet attemperator line block valve (HV-22134),
the reheat inlet attemperator line flow control valve (FV-22120) is the " companion" valve.
Even though valves HV-2249, SV-2112, and HV-22134 were not
- stroked, their companion valves were.
In each instance, the companion valve did go closed as required.
The actuation signal was removed from the XCR and the valves remained closed. The valves were reopened only after operator action of the appropriate handswitches and other operator actions per normal procedures.
Satisfactory operation of Loop I and Loop II Superheat Header Outlet Stop Check Valves (HV-2223 and HV-2224) and Loop I and Loop II Hot Reheat Header Stop Check Valves (HV-2253 and HV-2254)was verified based upon a review of past loop shutdown experiences.
The valves are actuated to a closed position by the action of an XCR and related control relay.
The control relay remains energized and the vaive remains closed when the actuation signal is removed from the XCR.
Resetting the control relay requires rasetting the XCR and is done by the operator moving the valve controlling handswitch to the closed position.
Opening the valve requires further operator actions. Data from several hot restarts of loop shutdowns (September 12, 1977;. September 23, 1977; October 10, 1977; December 11, 1980; and February 2,
1981) show these valves closed as required and remained closed when the actuation signal to the XCR was removed.
The valves were reopened only after operator action of the appropriate handswitch and other operator actions per normal procedures.
CONCLUSIONS The valves operated by the steam / water dump system, actuated as a consequence of receiving each of the three steam / water dump actuation signal s, were verified as operating in a satisfactory manner and in the manner depicted by the FSV electrical drawings and schematics.
Each valve changed from its normal posi tion to an actuated (emergency) position upon receipt of an actuation signal and remained in its actuated position when the actuation signal was removed.
Specific operator-initiated actions were subsequently required to reset the XCR and to physically change each valve back to its original position.
Seventeen of the valves listed in Table 1 were directly functionally tested (stroked) and observed to remain in their actuated position af ter removal of the actuation signal.
Three of the valves were not stroked because of plant conditions but were verified as operating in a satisfactory manner on the basis of commonality between the control circuitry of the unstroked valve and its " companion" valve.
~
P-82054 i
ATTACHf1ENT Page 5 l
Four of the valves were not stroked because of plant conditions but were verified as operating in a satisfactory manner on the basis of review of prior plant data involving loop shutdown and subsequent
" hot restart" of that loop in accordance with approved System Operating Procedures then in effect.
The four valves in question did operate in a satisfactory manner.
Based on the test results obtained, the review of prior operating data, and the analytical reasoning described above, it is concluded i
that satisfactory operation of the steam / water dump system, in the manner shown by FSV schematics and elementary diagrams, has been verified.
P-82054 AHachmenf
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