ML20154L066
| ML20154L066 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 05/21/1988 |
| From: | Hukill H GENERAL PUBLIC UTILITIES CORP. |
| To: | NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM) |
| References | |
| C311-88-2057, NUDOCS 8805310138 | |
| Download: ML20154L066 (5) | |
Text
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i GPU Nuclear Corporation
".i10 tuclear
=e =gr8o o
Middletown, Pennsylvania 17057 0191 717 944 7621 TELEX 84 2386 Writer's Direct WI Nurnber:
May 21, 1988 C311 2057 U.S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, D.C.
20555 Gentlemen:
Three Mile Island Nuclear Station, Unit 1 (TMI-1)
Operating License No. DPR-50 Docket No. 50-289 10 CFR 50 Appendix R Noncompliances and Exemption Request GPU Nuclear has identified additional Appendix R fire conditions which could adversely affect valves required for shutdown. The valves involved are:
pressurizer spray valve RC-V-1; intermediate cooling valves IC-V-3 and IC-V-4; makeup valves MU-Y-217, MU-V-16 A/B/C/D, MU-V-18, and letdown valves MU-V-3, and MU-V-2A/28; and valves MU-Y-2A/28, MU-V-3, MU-V-4, and MU-V-5 for letdown isolation.
NRC Region I personnel were verbally informed on October 22, 1987 of the conditions involving valves RC-Y-1, IC-V-3, and IC-Y-4, and the corrective actions taken.
Letdown isolation valves MU-Y-2A/28, MU-V-3, MU-Y-4, and MU-Y-5 were not discussed since this condition was still under evaluation. These conditions were identified as a result of the same review effort which identified earlier noncompliances.
The condition concerning makeup valves MU-V-217, MU-Y-16 A/B/C/D, MU-V-18, and letdown valves MU-V-3 and MU-V-2A/2B were recently identified as a result of ongoing maintenance of j
the fire hazards analysis, The following discussion documents previously described corrective action for valves RC-Y-1, IC-V-3 and IC-V-4, and documents the results of our evaluation for the makeup valves and for the letdown isolation valves. This letter forwards an exemption request to allow credit for adequate physical separation, area wide detection and automatic suppression in lieu of protection of cables for the above letdown isolation valves, in fire areas j
AB-FZ-4 and FH-FZ-1.
Pressurizer Spray Valve RC-V-1 A fire in CB-FA-1 could cause spurious opening of pressurizer spray valve RC-Y-1 resulting in a depressurization of the reactor coolant system.
The pressurizer spray block valyn, RC-Y-3, is not arotected for a fire in CD-FA-1 and the reactor coolant pump DC trip control c',.uits for all four pumpi may 8805310138 880521 q
PDR ADOCK 05000289 0g p
PDR GPU Nuclear Corporation in a subsidiary of the General Public Utilities Corporation O
C311 2057 May 21, 1988 be damaged. The req"ired manual action is to trip the reactor coolant pumps at the 6900 V switchgar at Elevation 322 in the Turbine Building to mitigate i
the depressurization transient. The time available for this manuel action is 45 minutes and adequate manning is available to accomplish this action.
Therefore, there is reasonable assurance that it can be accomplished without affecting the capability to safely shutdown the plant.
The emergency procedure for CB-FA-1 already directed the operator to trip the RCP's at the 6900 V switchgear if unable to trip from the control room. This procedure has been further revised to direct the operator to trip the RCP's from the 6900 Y l
switchgear h kC-Y-1 spuriously opens and the ability to close block valve RC '.'-3 ur trip the RCP's from the control room is lost. Procedural revision i
has corrected the above condition.
Credit for normal occupancy of CB-FA-1 is no longer required for the RC-Y-1 issue.
No exemption is required as this action is interpreted as being "emergency control station (s)" p'r 10 CFR 50 Appendix R, Sectirrn III.G.1(a).
Intei adiate Cool'cg Valves IC-V-3 and IC-V-4 A deficiency rega ding the mitigating action to correct ESAS spurious operation due ;a a fire in CB-FA-1, CB-FA-2a, CB-FA-?' and CB-FA-2f had been identifiea. Spurious reactor building isolation initiated by the ESAS system may 1 id to spurious cWing of intermediate cooling valves IC-V-3 and
- C-V-4 To re-establish RCP thermal barrier cooling, the reopening of IC-V-3 and IC-Y-4 is required. The Appendix R anrlysis had icentified compensatory manual actions of using the Remote Shutdown System Transfer Switches for Intermediate Cooling system components to isolate ESAS circuits for these fire areat, Heever, it has been determined that for fires in CB-FA-1, CB-FA-2d ara C8-FA-2f for both valves IC-V-3 and IC-V-4, and in CB-FA-2a for valve IC-/-3 only, the remoto shutdown transfer switch power supplies may be damaged which would preclude isolation of the ESAS conticts.
To correct this situation, a modification will be irplemented during the 7R refuelf r.g outage to rewire +.he Intermediate Cooling system transfer switches in Remote Shutdown Transfer Switch Panals A and B.
The modification will allow isolation of ESAS contacts to the IC-V-3 and IC-V-4 solenoids oy the use of the manual control switch contacts instead of auxiliary relay contacts Nnich requires external control power).
No exemption is reouired.
1 As a comensatory measure for the interim, the existing roving fire watch and normai cccupancy provides reaswable assurance that a fire would be discovered in its formati"o stages and controlled such that significant fire damage in these are., would 6t oc:ur.. In addition, emergency procedures advise the operator t the !
's may *.L ia te be tripped at the 6900V switchgear in the Turbine di" x: that "
- nd IC-Y-4 must be opened locally.
C311 2057 May 21, 1988 Makeu) Valves MU-V-217, MU-V-16 A/B/C/0, MU-V-18, and Letdown Yalves MU-V-3 and MJ-V-2A/2B A fire in CB-FA-1, CB-FA-2a, CB-FA-2d or CB-FA-2f may spuriously actuate ESAS train A, while a fire in CB-FA-2b, CB-FA-2c, C3-FA-2e and CB-FA-29 could cause a spurious actuation of ESAS train B due to loss of two vital power supplies for the control logic.
This spurious actuation initiates HPI, starting respectively the train A or train B makeup pump and opening its associated HPI valves (i.e. MU-V-16A and 16B or MU-Y-16C and 16D).
A fire in CB-FA-2d or CB-FA-20 could additionally cause spurious op9ning of MU-Y-217 and render MU-V-18 inoperable from the Centrol Room.
These spurious operations can be corrected by tripping the makeup pump (s) at the 1D or 1E 4160V switchgear or by tripping the switchgear in CB-FA-3a or CB-FA-3b, respectively.
Since the time available is approximately one hour and adequate manning is available, there is reasonable assurance that this manual action can be accomplished without affecting the capability to shetdown the plant.
J Additionally, spurious ESAS actuation due to a fire in CB-FA-2f or CB-FA-2g may respectively close the letdown valves MU-Y-3 or MU-Y-2A and 28. Since letdown can be delayed for up to 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> these valves can be manually operated.
It should be mentioned that manual operation of Hil-Y-3 due to loss of air during a fire in CB-FA-2f and of PU-Y-18 for mitigating the spurious opening of MU-V-217 during a fire in CB-FA-2e were previously identified in the FHAR Rev. 9.
The fire emergency procedure is being revised to incorporate these manual actions in the fire zones mentioned above.
These manual actions are interpretea as being "emergency control stations" per 10 CFR 50 Appendix R, Section III G 1(a), and therefore no exemption is required.
Letdown Isolation Valves MU-V-2A/28, MU-Y-3, MU-V-4 and MU-V-5 The following exemption is requested:
Exemption Requested, Exemption is requested from the requirements of Section III.G.2 of 10 CFR 50, Appendix to the extent that it requires redundant shutdown related component > be separated by 20 ft with no intervening combustibles, for fire areas AB-FZ-4 and FH-FZ-1.
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C311 2057 May 21, 1988 Justification A fire in AB-FZ-4 or FH-FZ-1 could damage circuits for the letdown valves, which would preclude letdown icolation from the control room. Letdown can be isolated by any of the followina redundant valves:
a.
HU-V-2A and 2B, or b.
MU-Y-4 and 5, or c.
MU-Y-3 Spurious openine d MU-V-5 concurrent with loss of intermediate cooling to the letdown coolers could result in damage to the icw pressure portion of the letdown system. Loss of the letdown function is acceptable for the first 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> based on holding the reactor coolant temperature constant while reactor coolant pump (RCP) seal injection adds inventory to the reactor coolant system. Letdown isolation can be accomplished since there is adequate separation and sufficient mitigating features to compensate for intervening combustibles between redundant valve circuits as described below.
Within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />, RCP thermal barrier cooling will be reestablished and RCP seal injection will 're secured.
Once the seal injectfun is secured, the letdown function is not requireo for an Appendix R shutdown event.
In AB-FZ-4, the circuits associated with MU-V-5 are approximately 40 f t, evay from the cable trays used for MU-Y-2A and 2B circuits; MU-Y-4 and its circuits are located outside of this zone.
In FH-FZ-1, the MU-Y-3 circuits are separated by approximately 36 ft. from the trays used for MU-V-2A and 28.
Both fire zones ara provided with area wide ionization smoke detection and automatic suppression systems protecting the entire floor and the cable trays.
The intervening space between the valve circuits contains combustible materials primarily in t% form of cables in trays. A fire involving cable 1
in,ulation would initially burn slowly with much smoke but with low heat I
release. The fire detection system is capable of alarning during the
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formative stages of the fire before serious damage would result.
The fire brigade would be dispatched and would put out the fire using manual fire fighting equipment which includes portable extinguishers and hose lines from nearby hose reel stations. Control of transient combustibles in this area is provided through administrative controls.
If the fire spread rapidly and significant temperature rise occurred, the automatic sprinkler system would actuate to control the fire. Pending actuation of the sprinkler system and/or arrival of the fire brigade, the horizontal distance between the valve circuits in either AB-FZ-4 and FH-FZ-1, i
specified above, provides reasonable assurance that at least one redundant valve combination would be free of fire damage.
The presence of combustible i
materials in the intervening space between the valves is not significant.
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C311 2057 May 21, 1988 Circuits for functionally redundant valves MU-Y-2A and MU-V-28, and MU-Y-4 and MU-V-5 in AB-FZ-4; and MU-Y-2A and MU-Y-2B, and MU-V-3 in FH-FZ-1 are adequately separated by distance with sufficient mitigating features to compensate for the existence of intervening combustibles to preclude damage to redundant valve circuits.
The basis for this exemption request is analagous
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to that previously accepted by NRC in the letter dated December 30, 1986, Enclo ure I, Part III.4 The underlying purpose of the rule is to accomplish safe shutdown in the event of a single fire and maintain the plant in a safe condition. The rule requires fire protection for circuits and components associated with shutdown-related valves.
In the areas where exemption is requested, adequate i
separation as well as area wide detection and automatic suppression assure 1
that any single fire will not result in the loss of safe shutdown capability.
Thus, the underlying purpose of the rule is satirfied by providing adequate separation, area wide detection and automatic suppression in AB-FZ-4 and i
FH-FZ-1.
Therefore, the exemption being requested meets the special circumstances delineated in 10 CFR 50.12(a)(2)(iii), in that application of the regulation in this particular circumstance is not necessary to achieve the underlying purpose of the rule.
In additfoa, the special circumstances of 10 CFR 50.12(a)(2)(iii) apply in that providing additional protection features, required by the regulations, would not result in a significant increase in the leve; of protection provided and would result in undus hardship and cost sir,nificantly in excess of those incurred by others similarly situated.
These casts consist of additional engineering, procureinent of material, fabrication and installation costs.
NRC review and approval of the above exemption is requested.
If any additional information is re quired, please contact us.
Sincerely,
.D. ' k 11 Vice President and Director, TMI-i HDH/DJD/jbw:1171 A cc:
J. Stolz, USNRC R. Hernan, USNRC j
W. Russell, USNRC, Region I R. Conte, USNRC, TMI-1 Site D. Kubicki, USNRC, PEISCB
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