ML20058C667
| ML20058C667 | |
| Person / Time | |
|---|---|
| Site: | Maine Yankee |
| Issue date: | 07/16/1982 |
| From: | Maine Yankee |
| To: | |
| Shared Package | |
| ML20058C650 | List: |
| References | |
| NUDOCS 8207260417 | |
| Download: ML20058C667 (5) | |
Text
MAINE YANKEE ATOMIC POWER COMPANY 1.1 FUEL STORAGE Aonlicability: Applies to the capacity and storage arrangements of the new and spent fuel facility.
Objective:
To describe and define those aspects of fuel storage which relate to the prevention of criticality in the fuel storage facility.
Soecification:
A.
The new and spent fuel pit sructures including fuel racks are designed to withstand the anticipated earthquake loadings as Class I structures. -The spent fuel pit is lined with stainless steel to ensure against loss of water.
B.
Fuel is stored vertically in racks.
The racks are designed to maintain fuel assently center to center distances that will assure Kerr is less than or
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equal to 0.95 even with the pit filled with unborated
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water.
C.
Whenever there is fuel in the spent fuel pit, except for initial new fuel storage, the spent fuel storage pit is filled with water borated to the refueling water boron concentration. This concentration matches that in the reactor cavity and refueling canal during refueling operations.
D.
Spent fuel shipping casks shall not be lifted over
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the spent fuel storage pit.
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8207260417 820721 1.1-1 07/16/82 PDR ADOCK 05000309 P
MAINE YANKEE ATOMIC POWER COMPANY 3.13 REFUELING OPERATIONS Ato FUEL CONSO_IDATION
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Applicability:
Applies to operating limitations during refueling operations.
Objective:
To minimize the possibility of an accident occurring during refueling operations that could affect the health and safety of plant personnel and the public.
Specification:
A.
The following conditions shall be satisfied during refueling
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operations:
1.
The containment venting and purge system, including inlet and
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outlet trip valves that isolate the ventilation system in
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response to radiation monitors, shall be operable, with the
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discharge filtered through the high efficiency particulate air
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filters and charcoal absorbers.
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Exception: The high efficiency particulate air filters and
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charcoal absorbers may be bypassed during containment main-
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tenance activities which may be detrimental to these filters
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(welding, painting, etc.), provided that the containment purge
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trip valves remain trippable both manually and automatically in
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accordance with Spec. A.3 below and prompt notification is
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given the NRC.
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2.
Two radiation monitors that initiate isolation of the contain-ment ventilation system, shall be tested and verified to both be operable immediately prior to fuel handling operations and remain operable during fuel handling operations. The two
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monitors shall be located on the containment fuel handling area
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level, shall be part of the plant area monitoring system, and shall employ one-out-of-two logic for isolation.
Exception: The valve trip system may be bypassed for a
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period not to exceed 0.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> daily to facilitate routine
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testing of the radiation monitors.
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Remedial Action: Should one of the area monitors become inoperable, repairs shall be affected immediately and the logic shall revert to one-out-of-one for isolation. Refueling
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operations may continue for a maximum of 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> in this
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mode.
3.
The capability of the containment purge trip valves to res-
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pond to a trip signal from the radiation monitors shall be
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tested immediately prior to fuel handling operations and
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weekly thereafter.
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4.
Radiation levels in the containment and spent fuel storage areas shall be monitored continuously.
3.13-1 07/16/82
MAINE YANKEE ATOMIC POWER COMPANY 5.
Whenever core geometry is being changed, neutron flux shall be continuously monitored by at least two wide range logarithm monitors, with each monitor providing continuous visual indication in the control room with at least one monitor
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generating an audible neutron count rate in the containment.
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When core geometry is not being changed, at least one source range neutron monitor shall be in service.
6.
At least one residual heat removal pump and heat exchanger shall be in operation.
Exception: This system may be shutdown for a maximum of 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> to facilitate upper guide structure assembly removal or other special maintenance operations. During such periods the reactor coolant temperature shall be continuously monitored and the initiation of core cooling flow shall be continuously available.
7.
Both RHRS loops A and B shall be operable when the water level above the top of the irradiated fuel assemblies seated within the reactor pressure vessel is less than 23 feet.
8.
During reactor vessel head removal and while refueling operations are being performed in the reactor, the refueling boron concentration shall be maintained in the reactor coolant system and shall be checked by sampling on each shift to insure that the baron concentration is such to maintain the core 5%
delta k/k subcritical.
9.
Direct communication between personnel in the control room and at the refueling station shall be operable whenever changes in core geometry are taking place.
- 10. A minimum of 23 feet of water above the top of the core shall be maintained whenever spent fuel is being handled.
- 11. Irradiated fuel shall not be handled until 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> after reactor shutdown.
Remedial Action:
If any of the conditions in Specification A are not met, all refueling operations shall cease immediately; work shall be initiated to satisfy the required conditions, and no l
operations that may increase the reactivity of the core shall be made.
B.
The following conditions shall be satisfied during Fuel
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consolidation:
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1.
Irradiated fuel shall not be consolidated until it has been
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cooled at least 120 days after reactor shutdown.
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C.
Prior to each refueling a complete check out, including a load l
test, shall be conducted on fuel handling cranes that will be used l
to handle spent fuel assemblies.
l 3.13-2 07/16/82 i
MAINE YANKEE ATOMIC POWER COMPANY D.
Whenever spent fuel is being handled in the spent fuel pit, the fuel building ventilation systems shall be in operation with the discharged air passing through a filter pack containing a charcoal filter before going to the primary vent stack.
E.
Spent fuel storage racks may be moved only in accordance with written procedures which ensure that no rack modules are moved over fuel assemblies.
Basis:
The equipment and general procedures to be utilized during refueling are discussed in the FSAR. Detailed instructions, the above specifi-cations and the design of the fuel handling equipment incorporating built-in interlocks and safeguards systems provide assurance that no incident could occur during the refueling operations that would result in a hazard to public health and safety.
The exception to paragraph 3.13.A.1 permits operations which may be
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detrimental to the integrity of the filters to be conducted during
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refueling operations, thus eliminating unnecessary outage delays.
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Analysis has shown that a refueling accident occurring in excess of 72
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hours after shutdown (Specification 3.13.E) will not result in offsite
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consequences in excess of 10CFR100 even if no credit is taken for
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filtration or containment isolation.
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The exception to paragraph 3.13.A.2 permits routine testing of the
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radiation monitors without incurring unnecessary wear of the purge
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valve resiliant seals. Weekly testing of these trip valves is
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sufficient to insure their operability.
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Whenever changes are not being made in core geometry, one flux monitor is sufficient. This permits maintenance of the instrumentation.
Continuous monitoring of radiation levels and neutron flux provides immediate indication of an unsafe condition. The residual heat removal flow is used to remove core decay heat and maintain a uniform boron concentration.
l A single cooling mechanism is sufficient to remove decay heat but single failure considerations require that two mechanisms be OPERABLE.
The shutdown margin as indicated will keep the core substantially subcritical, even if the highest worth CEA's were inadvertently withdrawn from the core without compensating boron addition.
Periodic checks of refueling water boron concentration insure the proper shutdown margin. Communication requirements allow the control room operator to inform the refueling station operation of any impending visual condition detected from the main control board indicators during fuel movement.
In addition to the above engineered safeguards systems, interlocks are l
utilized during refueling to insure safe handling. An excess weight interlock is provided to prevent excess loading of a fuel assembly, should it inadvertently become stuck.
3.13-3 07/16/82 I
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e MAINE YANKEE ATOMIC POWER COMP ANY The charcoal filter installed in the fuel handling building exhaust will handle the full 15,000 cfm capacity of the normal ventilation flow.
The offsite thyroid dose as calculated for the fuel handling incident is well below the 10 CFR 100 guideline dose. Valve alignment check sheets are completed to protect against sources of unborated water or draining of the system.
In the analysis of the refueling accident conducted by the Staff, 23 feet of water and 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> of decay time were used to limit exposures to 10% of 10 CFR 100.
Procedures are required for movement of spent fuel racks to avoid unnecessary risk of spent fuel damage caused by dropping spent fuel racks.
The 120 day cooling period after reactor shutdown allows
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substantial radioactive decay. This ensures that the dose consequences
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of a consolidated spent fuel handling accident are bounded by the
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consequences of the design basis spent fuel drop accident.
It also
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ensures that the maximum outlet temperatures for the limiting fuel
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assembly and the consolidated fuel storage bundle are both well below
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the saturation temperature at the cell outlet for any storage array.
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3.13-4 07/16/82
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