ML17199U174
| ML17199U174 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 11/17/1987 |
| From: | Silady J COMMONWEALTH EDISON CO. |
| To: | Murley T Office of Nuclear Reactor Regulation |
| References | |
| 3839K-BS, NUDOCS 8802160143 | |
| Download: ML17199U174 (16) | |
Text
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CommonvAth Edison One First Nati6'11'Plaza, Chicago, Illinois Address Reply to: Post Office Box 767 Chicago, Illinois 60690. 0767 November 17, 1987 Mr. Thomas E. Murley, Director Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, DC 20555 subject:
Reference:
Dear Mr. Murley:
Dresden Station Units 2 and 3 Additional Information on Appendix R Alternate Shutdown
~c Docket Nos.
50-:.~_37 & 50-:~~_9 ____. --------*---
Letter from I. M. Johnson to T. E. Murley dated September 10, 1987 In the referenced letter, Commonwealth Edison company (CECo) provided information clarifying various aspects of Dresden complianc~ with Appendix R Items III.G.3 and III.L related to alternate safe shutdown capability.
During subsequent discussions on November 9, 1987 and November 10, 1987, it has been determined that several of the attachments to the reference were incompletely assembled and transmitted.
Enclosed, please find replacement copies for Attachments 2, 3, and 4 to the Reference.
The first attachment of the Reference (SER mark-up) and the fifth attachment (revised exemption request) are not affected.
Please replace the previously transmitted copies of the affected attachments with those enclosed.
We apologize for any confusion or inconvenience this may have caused.
It was also noted that Attachment 2 refers to, but does not identify, References (1) and (2).
The appropriate references are as follows:
(1)
Letter from J. R. Wojnarowski to H. R. Denton dated May 30, 1986.
(2)
Letter from I. M. Johnson to H. R. Denton dated April 14, 1987.
Finally, during* the November lO, 1987 conference call CECo was requested to Clarify the time requirement for pulling Electromatic Relief Valve (ERV) fuses.
The ERV fuses must be pulled within 10 minutes after scram.
This is the assumption made in the time line analysis for
Mr. T. November 17, 1987 determining the time available to establish reactor water make-up.
The analysis assumed that one CER~i' is stuck open :Joi 10 minutes after scram occurs.
Please contact this office should furthei information be required.
. ;?.J,,. ~
Enclosures cc:
M. Grotenhuis - NRR Dresden Resident Inspector Yours very truly,
.** '9tfJM4_
J. A_. ~iladP Nuclea*r Licensing Administrator A. B. Davis - NRC RIII Administrator 3839K/bs
ATTACHMENT 2 Information in the SER Req~iring Clarification
- l.
Section 2.2 (page 2)
In this section the following statement is made:
"As part of their reverification effort, the licensee examined the need for providing alternate safe shutdown capability for Units 2 and 3 for a fire in any fire area or its equivalent fire area.
The licensee defined an equivalent fire area as one or more fire zones which border other fire areas, and is either separated by a 3-hour rated fire barrier or by equivalent fire protection.
Where a 3-hour barrier was not provided, the licensee requested an exemption from applicable Appendix R requirements.
Originally, CECo interpreted 10 CFR Appendix R Section III.G.3 requirement for independence of alternate safe shutdown systems to mean that these systems and their associated components are required to be separated by 3-hour rated fire barriers.
Where barriers between alternate safe shutdown systems could not be upgraded to 3-hour barriers, an eiemption request from the requirements of Sections III.G.3 and III.L of Appendix R were submitted and justified.
On April 8, 1986, CECo personnel participated in a meeting with the NRC.
staff.
NRR reviewer John Stang stated NRR's interpretation of Section III.G I
of Appendix R.
According to this interpretation:
A.
The separation criteria of Section III.G.2 does not apply to alternative safe shutdown systems,
ATTACHMENT 2 Page 2 B.
If the alternative safe shutdown capability option is employed in the Appendix R compliance analysis, then exemption requests are only necessary from the 111.G.3 requirements for fixed fire suppression and detection in the area, room, or zone under consideration, and C.
The independence requirement of 111.G.3 is demonstrated by the presence of fire protection measures or combina-tion of measures (e.g.; substantial barriers, spatial separation, automatic detection, automatic suppression) which assure that the alternative safe shutdown systems will be free of fire damage for fires in the area, room, or zones for which the alternative capability is provided.
Thus exemptions from the requirements of 111.G.3 for lack of fire barriers between alternative shutdown components are not necessary and will not be granted.
Based on this NRR interpretation of Appendix R Section 111.G.3, CECo withdrew several exemption requests [See Reference (l)]. Thus, the statement in the S~R is not completely accurate.
- 2.
Section 2.2 (page 4)
The SER states on page 4, The licensee has provided alternative hot shutdown capability for a fire in any specific fire area listed above independent of the required hot shutdown equipment and cabling for the specific area as
ATTACHMENT 2 Page 3
- required by Appendix R,Section III.G.3."
Dresden station has alternate hot shutdown capability that is independent of the affected fire area,. In order to establish independence, local isolation and control switches have been installed.
It should be noted that the independence of this equipment is established when local control is taken.
- 3.
Section 2.4 The second modification described in this section has been cancelled.
The NRC was informed of this change in Reference (2).
The NRC was given a list of all Appendix R modifications in the schedular exemption request.
- 4.
Section 3.1.2 In paragraph 2 it should state that the HPCI pump takes "suction from either the contaminated condensate storage tank (CCST), or the torus after torus high level or depletion of the CCST, whichever comes first."
In the event torus high water level is reached, HPCI pump suction will be switched over to the torus even if the CCST has not been depleted.
- 5.
Section 3. 1. 3 The electromatic relief valves are not used to control reactor coolant pressure.
Instead, the "Target Rock" valve in its mechanical mode and the mechanical safety valves are used for pressure control.
6.
Sec t i o ri s 3. 1 t5"': a n d 3. l.'-6~
No credit is taken for the availability of control room instrumentation.
- 7.
Section 3.3 ATTACHMENT 2 Page 4 Since cold shutdown repairs are allowed by Appendix R, reference to these repairs should be deleted.
This section should only discuss hot shutdown repairs.
A listing of the cold shutdown repairs is provided below for your information.
A.
Shutdown Cooling Pumps and RBCCW
- 1.
If a fire takes out the main feed cables to reactor building Buses 23-1 and 24-1, or 33-1 and 34-1, attempt to establish the crosstie between 24-1 and 34-1 and/or to simultaneously feed 23-1 and 33-1 from the 2/3 diesel generator.
If these actions are not possible, connect temporary cables from the required motors to spare breakers at the opposite unit.
- 2.
If only the motor feeds are damaged, remove the damaged cable section and splice a section of new cable in its place.
- 3.
In either case, jumper the breaker controls (or use local control) to force closure.
Verify proper direction of rotation.
B.
LPCI Pumps and Auxiliaries
- l.
If Bus 24-1 or 34-1 is disabled, attempt to establ~sh the crosstie between these two buses.
If this cannot be done,
~
ATTACHMENT 2 llllllll" Page 5 connect temporary cables from the required motors and 480-V switchgear to breakers at the opposite unit.
- 2.
If the 4-kV buses are still energized but the feeds to LPCI loads are damaged, remove the damaged cable section and splice a section of new cable in its place.
In any case, jumper the breaker controls (or use local control) to force closure.
Verify proper direction of motor rotation at both the 4-kV and 480-V levels.
C.
CCSW Pumps If Bus 24-1 or 34-1 is disabled, attempt to establish the crosstie between the two buses.
If this cannot be done, connect temporary cables from the required motors to breakers in the opposite unit SWGR 23-1 and 24-1 or 33-1 and 34-1.
D.
Relief Valves
- l.
If any one valve is still operational, disconnect cables from the penetrations for the disabled valves and jumper these pene-trations to the energized 125-Vdc penetration.
- 2.
If all five valves are disabled, remove all relief valve cables from their penetrations, jumper the penetrations together, and connect a temporary cable from them to the 125-Vdc source at
ATTACHMENT 2 Page 6 the nearest switchgear that has control power available.
Use the opposite unit, if necessary.
Verify energization..
(NOTE:
The cable used for this purpose must first be used for repositioning the recirculation loop valves, if necessary.)
E.
LPCI Emergency Air Coolers/CCSW Emergency Air Cooler Connect temporary cables to a spare breaker or starter at the nearest energized MCC (probably in the opposite unit).
Close the breaker, or jumper the starter controls to force start.
Open normally closed valve to provide cooling water from the 2/3 diesel generator cooling water pump to the LPCI emergency air coolers.
F.
Recirculation Loop Valves and Shutdown Cooling Valves (Inside Drywell)
Connect temporary cables from the drywell penetration to a spare breaker or starter at the nearest energized MCC.
It is not necessary to use a reversing starter. Determine first whether the "open" con-tactor of the original starter is the one with straight-through or with phase-reversed connections.
If phase-reversed, interchange two of the leads at the temporary source.
Close the breaker or jumper the starter controls, while monitoring the current in one phase with a clamp-type ammeter.
When the current sud lenly increases,
~ATTACHMENT 2 Page 7 trip the breaker.
Detailed procedures exist to cover this action.
Once the valve has been repositioned as desired, the temporary cable can be used for other purposes (e.g., relief valves).
G.
Reactor Building 125-V Distribution Panel Detailed procedures exist for the installation of a temporary cable to the opposite units 125-Vdc reserve supply and to reconfigure that supply to be fed from the unaffected unit's batteries.
H.
4-kV/480-V Feed Breaker Control Detailed procedures exist for severing damaged cables at the switch-gear or MCC and identifying terminals to be jumpered to force the desired operation.
I.
Transfer From Main to Reserve 125-~ and 250-Vdc Feeds Detailed procedures exist for repositioning slugs and closing breakers to establish reserve de feeds to distribution panels and switchgear.
J.
Open Valves TCV-3904A, TCV-3904B, and TCV-3904C Detailed procedures exist for cutting the cables at these valves thereby causing them to fail open.
Section 3.3(1) also states that makeup water is required for the isolation conden-ser 20 minutes after the scram and initiation of the isolation conde1ser.
This
e ATTACHMENT 2 Page 8 is not the case.
Actually makeup is required 20 minutes after initiation of the isolation condenser only.
Section 3.3(2) covers a repair that was required as an interim measure only.
It is no longer required because the modifications have been completed.
The existing paragraph should be deleted and replaced by the following new para-graph:
"The licensee has identified the need for possible repairs in several circuits for achieving hot shutdown, as a result of common power source deficiencies.
The staff has evaluated these repairs in Subsection 3.4.1 of this SE."
- 8.
Section 3.4. 1 CECo would like to clarify the position on circuits sharing a common power source.
As stated in the 1987 SER, procedures require the operator to manually trip all non-safe shutdown loads supplied by a common bus.
Coordinated fault protection has not been credited for Appendix R.
As a result, the words "with coordinated fault protection for safe shutdown equipment" should be deleted from the first sentence in Section 3.4.1. Also, only local instrumentation is utilized for Appendix R.
The words, "Instrumentation and" should be deleted from the first sentence in Section 3.4. l.
- 9.
Section 3.4.2 CECo would like to clarify the position on common enclosure.
9.nACHMENT 2 Page 9 Commonwealth Edison's position as stated in the 1982 Associated Circuits Report is "Circuits that share a common enclosure with essential circuits will not allow propagation of a fire out of a zone since the zone is generally enclosed by fire barriers.
II The 1984 reanalysis expanded this position to fire areas or equivalent fire areas.
All electrical circuits have been designed with appropriate protection for their power cables from overcurrent conditions.
Based on the preceding, Section 3.4.2 should be rewritten as follows:
"The licensee states that appropriate means are provided to prevent fire propagation out of a fire area.
Furthermore, the licensee has stated that electrical circuits have been provided with appropriate protection from overcurrent cdnditions."
ATTACHMENT 3 Items Requiring Additional Docketed Information from CECo
- l. Section 2.2 (page 4)
This section of the SE~ states that there are 6 alternate shutdown paths as stated in earlier CECo submittals.
These are considered alternative methods since actions are taken outside the control room to operate and control safe shutdown equipment.
For all safe shutdown paths local instrumentation is used to monitor reactor level, pressure and normal process variables.
Since this is not the normal way of monitoring these variables, all safe shutdown paths (there are 10 in total) should be con-sidered alternative safe shutdown paths.
- 2.
Section 2.3 Hot shutdown paths A, B, E and Fare referred to as "normal" safe shutdown paths when they should be referred to as "alternative" safe shutdown paths for the reason stated above.
- 3.
Section 3.1.2 and 3.4.3 CECo has completed a detailed analvsis of MSIV closure/spurious operation.
J This analysis verifies that a single fire will not prevent both the inboard and outboard MSIV on any steam line from closing on a isolation signal.
SSD procedures will specify closure of the MSI~'s from the control room for the appropriate fire areas.
As a result of. this reanalysis, Section_3.l.2.l, page 6 could be rewritten as follows:
~
ATTACHMENT 3 W Page 2 "Excessive loss of reactor coolant inventory from the reactor vessel via the main steam lines during a fire event is preve~ted by automatic (Isolation signal) and manual (Main control panel) closure of the MSIV's.
11 Section 3.4.3, page 10, paragraph should not mention the MSIV's since spurious operation of an inboard or outboard MSIV will not provide a path for reactor coolant inventory (See Item 4 below).
- 4.
Section 3.4.3 CECo has also recently completed a reanalysis of the electrically operated relief valves.
This reanalysis was promulgated by the invalidation of an assumption that ungrounded d.c. hot shorts were not credible for the relief valves circuitry.
Based on this analysis, Section 3.4.3, page 10, paragraph one should read:
"A fire in Fire Areas RB2-I, RB2-II, RB3-I, RB3-II, TB-I, TB-III, and TB-V could result in the spurious operation of one relief valve.
In order to mitigate this potential spurious operation, power will be removed from the relief valve circuits via breaker operation for a fire in the following areas:
RB2-I, RB2-II, RB3-I, RB3-II, and TB-V.
(The ERV's will not operate when power is removed.)
A fire in Fire Areas TB-I and TB-III could prevent access to the 125Vdc breakers to remove power.
As a result, fuses will be removed from the relief valve circuits in the AEER room (Unit 2) and Reactor Building (Unit 3).
(Note:
An exemption request for relief valve circuit fuse pulling is enclosed.)
In addition, the auto-blowdown
ATTACHMENT 3 e Page 3 logic is disabled from the main control panel by engaging the auto-blowdown inhibit switch.
This action will prevent automatic/
spurious operation of the auto-blowdown system.
- 5.
Section 3.4.4 CECo has reviewed this sectio~ and a revision to Section 7.3 of the Exemption Requests is enclosed.
The revised exemption request should clarify the situa-tion for fuse replacement.
(,'
3839K ATTACHMENT ~
"LIST OF SEPTEMBER 1, 1987 CONFEREN9E
~ALL A~'J:'J:NDEE~"
B.
I.
J.
- w.
F.
J.
- c.
- c.
M.
3532K NAME Barth Johnson Kelly Pierce Fischer Si lady Launi Ruth CONFERENCE CALL w/NRR
~-~- J)RE~_DEN~PPRNDI~R SAFE-SH.!:JTQOWN
?.AF~'!_LEVAhUATION J~EPORT September l, 1987 10:30 a.m. (CST)
ORG Sargent & Lundy.
CECo - Nuclear Licensing Sargent & Lundy CECo - Engineering Sargent & Lundy CECo - Nuclear Licensing Sargent & Lundy Sargent & Lundy Grotenhuis NRR -
BO I II-2 A