United States Nuclear Regulatory Commission - Protecting People and the Environment

Refueling Water Level (Generic Letter 80-77)



GL80077 

                               UNITED STATES 
                       NUCLEAR REGULATORY COMMISSION 
                          WASHINGTON, D. C. 20555 

                              August 15, 1980 

ALL WESTINGHOUSE PRESSURIZED WATER REACTOR LICENSEES 

Dear Sir: 

Current Westinghouse Standard Technical Specification (STS) 3.9.10 require 
"As a minimum, 23 feet of water shall be maintained over the top of 
irradiated fuel assemblies stored within the reactor pressure vessel" during
movement of fuel assemblies or control rods when a plant is in Mode 6. From 
the vessel seated position a fuel assembly may need to be lifted in excess 
of 23 feet in order to clear the vessel flange for movement to the fuel 
transfer system. Typically, there is an additional 12 to 18 inches of upward
travel to insure that the fuel assembly is fully withdrawn into the 
manipulator crane outer mask. Consequently, part of the fuel assembly would 
be exposed if the depth of water over the assemblies in the core did no 
exceed 23 feet. 

The Staff has recently revised Westinghouse Standard Technical 
Specifications 3.9.8.2. 3.9.10 and Bases 3/4 9.8 and 3/4 9.10 to require at 
least 23 feet of water over the top of the reactor pressure vessel flange 
during movement of  fuel assemblies or control rods, copy enclosed. These 
changes assure that the minimum level of water over the fuel assemblies is 
approximately 33 feet - sufficient depth to prevent inadvertent exposure of 
a fuel assembly during transfer. 

You are requested to review your Technical Specifications and procedures and
to make whatever revisions are necessary to assure that exposure of fuel 
assemblies and control rods cannot occur during transfer while the plant is 
in Mode 6. Within 30 days of receipt of this letter, please advise us of the
measures if any, required to achieve this assurance for the facility and the
implementation schedule. 

                                        Sincerely, 


                                        Thomas M. Novak, Assistant Director 
                                          for Operating Reactors 
                                        Division of Licensing 

Enclosure:
As Stated 

cc:  w/enclosure Service Lists 
.

REFUELING OPERATIONS 

LOW WATER LEVEL 

LIMITING CONDITION FOR OPERATION 

3.9.8.2 Two independent Residual Heat Removal (RHR) loops shall be 
OPERABLE.* 

APPLICABILITY: MODE 6 when the water level above the top of the reactor 
               pressure vessel flange is less than 23 feet. 

ACTION: 

     a.   With less than the required RHR loops OPERABLE, immediately 
          initiate corrective action to return the require RHR loops to 
          OPERABLE status as soon as possible. 

     b.   The provisions of Specification 3.0.3 are not applicable. 

SURVEILLANCE REQUIREMENTS 

4.9.8.2 The required Residual Heat Removal loops shall be determined 
OPERABLE per Specification 4.0.5. 

*The normal or emergency power source may be inoperable for each RHR loop. 
.

REFUELING OPERATIONS 

3/4.9.10 WATER LEVEL - REACTOR VESSEL 

LIMITING CONDITION FOR OPERATION 

3.9.10 At least 23 feet of water shall be maintained over the top of the 
reactor pressure vessel flange. 

APPLICABILITY: During movement of fuel assemblies or control rods within the
reactor pressure vessel while in MODE 6. 

ACTION: 

With the requirements of the above specification not satisfied, suspend all 
operations involving movement of fuel assemblies or control rods within the 
pressure vessel. The provisions of Specification 3.0.3 are not applicable. 

SURVEILLANCE REQUIREMENTS 

4.9.10 The water level shall be determined to be at least its minimum 
required depth within 2 hours prior to the start of and at least once per 24
hours thereafter during movement of fuel assemblies or control rods. 
.

REFUELING OPERATIONS 

BASES 

MANIPULATOR CRANE (Continued) 

and 3) the core internals and pressure vessel are protected from excessive 
lifting force in the event they are inadvertently engaged during lifting 
operations. 

3/4.9.7 CRANE TRAVEL - SPENT FUEL STORAGE BUILDING 

     The restriction on movement of loads in excess of the nominal weight of
a fuel and control rod assembly and associated handling tool over other fuel
assemblies in the storage pool ensures that in the event this load is 
dropped 1) the activity release will be limited to that contained in a 
single fuel assembly, and 2) any possible distortion of fuel in the storage 
rocks will not result in a critical array. This assumption is consistent 
with the activity release assumed in the accident analyses. 

3/4.9.8 RESIDUAL HEAT REMOVAL AND COOLANT CIRCULATION 

     The requirement that at least one residual heat removal (RHR) loop be 
in operation ensures that (1) sufficient cooling capacity is available to 
remove decay heat and maintain the water in the reactor pressure vessel 
below 140F as required during the REFUELING MODE, and (2) sufficient 
coolant circulation is maintained through the reactor core to minimize the 
effect of a boron dilution incident and prevent boron stratification. 

     The requirement to have two RHR loops OPERABLE when there is less than 
23 feet of water above the reactor pressure vessel flange ensures that a 
single failure of the operating RHR loop will not result in a complete loss 
of residual heat removal capability. With the reactor vessel head removed 
and 23 feet of water above the reactor pressure vessel flange, a large heat 
sink is available for core cooling. Thus, in the event of a failure of the 
operating RHR loop, adequate time is provided to initiate emergency 
procedures to cool the core. 

3/4.9.9 CONTAINMENT PURGE AND EXHAUST ISOLATION SYSTEM 

     The OPERABILITY of this system ensures that the containment vent and 
purge penetrations will be automatically isolated upon detection of high 
radiation levels within the containment. The OPERABILITY of this system is 
required to restrict the release of radioactive material from the 
containment atmosphere to the environment. 

3/4.9.10 and 3/4.9.11 WATER LEVEL - REACTOR VESSEL MD STORAGE POOL 

     The restrictions on minimum water level ensure that sufficient water 
depth is available to rewove 99% of the assumed 10% iodine gap activity 
released from the rupture of an irradiated fuel assembly. The minimum water 
depth is consistent with the assumptions of the accident analysis. 

W-STS                            8 3/4 9-2                      JUN 23 1980 

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