ML19343D501
| ML19343D501 | |
| Person / Time | |
|---|---|
| Site: | Maine Yankee |
| Issue date: | 04/24/1981 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML19343D498 | List: |
| References | |
| NUDOCS 8105050027 | |
| Download: ML19343D501 (5) | |
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Q) l INTERIM SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGUALTION POSTFIRESHUTDbWNCAPABILITY l
i MAINE YANKEE A'TOMIC POWER STATION I
Section 3.2.1 of the SER on fire protection states that the licensee has acreed to provide additional information to demonstrate the capability to achieve safe shutdown conditions in the event of a fire in any of the fol-lowing areas: control room cable chase, protected cable vault, protected cable tray room, turbine building, circulating water pumphouse, primary auxiliary, building, reactor c,or.taiment, contaiment spray pump building, ventilation ecuipment and personnel airlock area, steam and feedwater valve area, and con-i tairnent penetration areas.
By letters dated May 31, 1978 and September 30, 1979, the licensee addressed l
Section 3.2.1 of the SER requirement. Further information was given to the NRC staff by means of a telephone call on March 12, 1980. A conference call on March 17, 1981 b.etween the licensee, NRC personnel and BNL provided further information.
The licensee proposes to use manual operations at local control stations to operate existing plant equipment. Several cable replacements are proposed to replace burned-out cables; fire protection and separation are relied on in many areas. Both submittals consider the use of boration of the reactor coolant system. The major problem with the submittals is that the loss of off-site power has not been addressed; the licensee has applied for an exemption for this requirement.
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The original submittal of May 31, 1978 reviews the plant area by area cr.sidering the major goals of alternative sh' tdown capability. The second u
subnittal uses a fornat that answers the NP.C concern.oiven in the Staff Posi-
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tien on Safe Shutdown Capability sent to the licensee on July 19,;1979.
Ue have evaluated the Maine Yankee post.' ire shutdown c.apability using i
NRC cuidelines " Staff Position, Safe Shutdown Capability" cated June 19, 1979 and NRC requirements in Section III.L of Appendix R to 10 CFR Part 50.
We i
have found that:
1.
It has not been shown that the post-fire shutdown circuitry is isolated from associated circuits.
Isolation should be such that i
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fire damage to associated circuits in a fire area will not prevent l
the operation of--shutdown equipment.
No isolation has been added or l
proposed in the _ licensee's subnittals for alternative shutdown l
capability.
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2.
Support functions could be lost due to a fire. A fire on the 11 foot or 21 foot elevation of the prinary auxiliary building could disable the luhe oil pumps used for all three charging punps. This same fire could' danage the power cables to the auxiliary charging a
pump which is the back-up co6ponent.
3.
Process monitoring was not considered by the licensee to be essen-tial. Certain measurenents were proposed to be obtained by entering containment, but no mention of potential radiation problens were noted. The licensee also proposed connecting portable power sup-plies, digital ammeters, and wheatstone bridges to obtain process measurements.
4.
The licensee stated that there was no requirement to have replace-ment cables on site.
In our telephone conversation of March 17, 1981, however, the licensee said that there were spare cables similar tio existing installed cabler stored in their site warenouse.
They did not have procedures that called for specific lengths of cables to be used to replace specific cables postulated to be de-stroyed by a fiqe.
5.
The procedures referred to in the submittals were not written for alternative shutdown capability.
Some of these previously written procetiures such as EP 2-31, Service Water Header Rupture, are not applicable to answering our present concerns.
6.
The nanpower requirenents for alternative shutdown capability have been addressed in the submittal of September 20, 1979. However, after the evacuation of the control roon, there are not enough men to fight a fire and do the necessary nanual operations for safe shutdown.
The licensee has relied on the outside fire departnent to satisfy the manpower requirenent in this instance.
7.
In several instances the licensee proposes to use the fire apparatus and f acilities for purposes other than fighting fires. Hoses would be connected from the residual heat removal heat exchangers to the fire mains; the diesel fire pump would be used to punp water from j
the fire pond for decay heat renoval.
8.
Repairs are proposed for hot shutdo'in.
Power cables to either the auxiliary charging punp or to a main charging pump would be run to l
replace one or more cables danaged in a fire.
9.
The post fire shutdown capability depends on fire protection and spacial separation in the protected cable tray room, the prinary auxiliary building, containment, containment spray building, ven-tilation equipment and personnel air lock area, stea, and feedwater valve area, and containment penetration areas.
We conclude that ti.e proposed alternate shutdown capability for the
\\'.af ne Yankee Power Station does not conform with NRC guidelines and require-e-ts and, therefore, is unacceptable.
We recommend the following:
A.
The alternative shutdown ' capability should be modified to meet the requirements of Section III L of Appendix R to 10 CFR Part 50, tak-i ing into consideration the above findings, t
B.
All support functions including lube oil, cooling, and power should
.be shown to be available for the equipnent used in the alternative r
shutdown capability.
C.
The process nonitoring should be shown to be capable of providing direct readings of the process variables necessary to control re-activity,' reactor coolant makeup, and reactor heat renoval.
Penn-anently installed instruments should be used to provide capability for reading pressurizer pressure, temperature and level, reactor coolant loop teqperatures, stean generator level and pressure, aux-iliary feedwater flow, condensate storage tank level and radiation levels, and reactor core flux density.
D.
All repair procedures for cold shutdown should be fully developed' and it should be verified that the materials for the repairs are maintained on site.
E.
The procedures for alternative hot and cold shutdown should be fully developed. The manpower for these procedures and for the repair procedures should be shem to be available on site and the work to be perfomed should be reasonable of the nanpower available.
F.
The water requirenents for core cooling and support functions asso-ciated with core cooling should be met without using the diesel fire punp and other systems designed for' fighting fires.
G.
Repairs to systems used to place the reactor in the hot shutdown operating mode should not be incorporated in the procedures estab-lished to bring the plant to hot shutdown.
H.
The licensee shodld demonstrate that alternative safe shutdown capability can be achieved with the loss of offsite power.
I.
The licensee should denonstrate that the potential operating problem i
with the contain*ent ventilation systen referred to in the Final Safety Analysis Report wculd not affect safe shutdown in the event of a fire.
J.
Section III.G of Appendix' R to CFR Part 50 requires cabling for or i
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associated with redundant safe shutdown systens necessary to achieve l
and raintain hot shutdown conditions be separated by fire barriers t
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having a three hour fire rating or equivalent protection (see Sec-tion III.G.2 of Appendix R). Therefore, if option III.G.3 is chosen for the protect. ion of shutdown capability, cabling required for or associated with the alternative nethod of hot shutdown for each fire area aust be physically sepaiated by the equivalent of a three-hour rated fire barrier from the fire area.
In evaluating an alternative shutdown nethod, associated circuits are circuits that could prevent operation or cause malfunction of the alternative train which is used to achieve and maintain hot shutdown conditions due to fire induced hot shorts, open circuits, or shorts to ground.
Safety related and nonsafety related cables that are associated with the equipment and cables of the alternative or dedicated nethod of shutdown are those that have a separation from the fire area less than that required by Section III.G.2 of Appendix R to 10 CFR 50 and have either (1) a connon power source with the alternative shutdown equiprent and the power source is not electrically protected from the post fire sgutdown circuit of concern by coordinated circuit breakers, fuses, or sinilar devices, (2) a. connection to circuits of equipnent whose spurious operation will adversely effect the shut-down capability, e.g., RHR/RCS isolation valves or (3) a conmon en-closure, e.g., raceway, panel, junction box with alternative shut-dow'n cables and are not electrically protected from the post fire shutdown circuits of concern by circuit breakers, fuses, or similar devices.
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For each fire area where an alternative or dedicated shutdown r-ethod, in accordance with Section III.G.3 of Appendix R 10 CFR Part 50 is provided by preposed nodifications, the following infomation is required to denonstrate that associated circuits will not prevent operation or cause nalfunction of the alternative or dedicated shut-down nethod.
(1)
Provide a table that lists ali equipnent including instrumenti tion and support systen equipnent that are required by the alternative or dedicated method of achieving and naintaining hot shutdown.
(2) For each alternative shutdown equipnent listed in (1) above, provide a table that lists the essential cable (instrumenta-1 tion, control and power) that are located in the fire area.
(3)
Provide a table that lists safety related and nonsafety related cables associated with the equipnent in cables constituting the alternative or dedicated nethod of shutdown that are located in the fire W ea.
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(d)
Show that fire induced failures of the cables listed in (2) and (3) above will not prevent cperation or cause nalfunction of l
the alternative or dedicated shutdown method.
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(5)
For each cable listed in (2) above provide a detailed elec-trical schematic drawing that shows how each cable is isolated from the fire area.
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K.
The: residual heat renoval systen is generally a low pressure system that interfaces with the'high pressure prinary coolant systen. To preclude a LOCA through this interface, we require conpliance with the reconnendations of Banch Technical Position RSB 5-1.
Thus, this interface most likely consists of two redundant and independent notor operated valves.
These two notor operated valves and their associated cable may be subject to a single fire hazard.
It is
,our concern that this single fire could cause the two valves to open resulting in a fire-initiated LOCA through the subject high-low pressure.systen interface.
To assure that this interface and other high-low pressure interfaces are adequately protected from the ef-fects of a single fire, we require the following information:
Identify each high-low pressure interface that uses. redundant electrically controlled devices (such as two series motor oper-ated valves)'to isolate or preclude rupture of any priaary cool-ant boundatf.
Identify the device's essential cabling (power and control) and describe the cable routing (by fire area) fron source to termina-tion.
Identify each location where the identified cables are separated by lets than a wall having a three-hour fire rating fron cables for tre redundant device.
For the areas identified in the above paragraph, provide the bases and justification as to the acceptability of the existing design or any Orcoosed rodifications.
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P00R OREM.
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