HBL-97-013, Annual Rept of Changes,Tests & Experiments for Plant for Jan-Dec 1996,per 10CFR50.59

Annual Rept of Changes,Tests & Experiments for Plant for Jan-Dec 1996,per 10CFR50.59

ML20197F830
Person / Time
Site:	Humboldt Bay
Issue date:	12/19/1997
From:	Rueger G PACIFIC GAS & ELECTRIC CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
HBL-97-013, HBL-97-13, NUDOCS 9712300301
Download: ML20197F830 (8)

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Pacific Gas and Electric Company - 245 Mar $et Street Room 937-N98 GrtgJry M. Rueger San Frenasco CA94105 Senior We Prestdent and

$[3B Power beraban P.O. Box 770000 San riancisco, CA 94177 419973-4fo4 Fax 415'973-2313 December 19,1997 PG&E Letter HBL-97-013 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Wasnington, D.C. 20555

. . 1 Docket No. 50-133, OL-DPR-7 Humbolot Bay Power Plant, Unit 3 10 CFR 50.59 Annual Report of Chances. Tests. and Experiments for January 1 throuah December 31.1996

Dear Commissioners and Staff:

Pursuant to 10 CFR 50.59, enclosed is the Annual Report of Changes, Tests, s and Experiments for Humboldt Bay Power Plant, Unit 3 (HBPP) for the reporting '

interval January 1 through December 31,1996.

Channes in the Facility As Described in the SAFSTOR Decommissionina Plan (SSDP)

The enclosed annual report provides a brief description of the 10 CFR 50.59 facility design changes, incluoing a summary of each safety evaluation. Each change was reviewed and accepted by the Plant Staff Review Committee (PSRC).

Channes in Procedures As Described in the SSDP The enclosed annual report provides a brief description of the 10 CFR 50.59 procedure changes, including a summary of each safety evaluation. Each

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change was reviewed and accepted by the PSRC.

Tests and Er.periments Not Described in the SSDP {

Ho tests or experiments were performed du;ing the repo' ting period that are not ,

described in the SSDP.

9712300301 971219 ,

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U. S. Nuclear Regulatory Commissic' December 19,1997 Page 2 The PSRC determined that none of the design changes or procedure changes involved an unreviewed safety question or a change to the HBPP Technical Specifications.

Sincerely, b

l W' *Y Gregor( M. Rueger cc: Richard F. Dudley Ellis W. Merschoff Kenneth E. Perkins Humboldt Distribution Enc!osure

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• PG&E Letter HBL-97-013 ENCLOSURE 10 CFR 50.59 ANNUAL REPORT OF CHANGES, TESTS, AND EXPERIMENTS JANUARY 1 THROUGH DECEMBER 31,1996 HUMBOLDT BAY POWER PLANT, UNIT 3 DOCKET NO. 50-133 1996 FACILITY CHANGES Listed below are the changes made to Humboldt Bay Power Plant, Unit 3 (HBPP)in 1996, along with brief descriptions of the changes and a summary of the safety evaluations. More complete records of these design changes have been reviewed by the HBPP Plant Staff Review Committee (PSRC), and the changes were determined not to involve an unreviewed safety question or a change to the HBPP Technical Specifications.

1. DCP E-00383 DCN HB3-SE-383 Provide Power to Power Panet No.1 From Emeraency Section of MCC-10 This modification changed the Power Panel No.1 power source to be the emergency section of MCC-10.

Power Panel No.1 provides 480-volt AC pewer for auxiliary equipment in the Unit 3 refueling building such as the caisson sump pump, reactor equipment drain tank (REDT) pumps, tuibine building drain tank punips, spent fuel pool recirculation pumps, reactor caisson manlift, and all refueling building lighting.

The AC power source for Power Panel No.1 was from Breaker 52-1012 in the normal section of MCC-10. The normal section of MCC-10 receives power from the Unit 3 2.4-kV bus throgh Load Center Transformer No. 5. The 2.4-kV bus is powered from the 60-kV auxniary bus through House T;ansformer No. 2. There is no alternate power source because the Unit 3 house transformer (HT3) has been removed from service. If the normal source of power to Power Panel No.1 were lost for an extended period of time, flooding at the -S6-foot elevation in the reactor caisson could occur due to the loss of both the caisson sump pump and the REDT pumps. At current leakage rates into the reactor caisson sump, a power loss for 10 hours1.157407e-4 days <br />0.00278 hours <br />1.653439e-5 weeks <br />3.805e-6 months <br /> would result in approximately 2000 gallons of water at the foot elevation. Loss of the spent fuel pool (SFP) recirculation pumps would result in increasing leve!s of Cs-137 in the SFP water. In addition, all lights in the refueling building will be inoperable.

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l MCC-10 also contains an emergency section that transfers to alternate AC power sources if the rarmal AC source as described above is lost. These alternate power sources are from Unit 1 through Breaker 52-510 on Load Center No. 5 and from a 60-kW propane engine-driven 480-volt generator. The emergency section provides power to the emergency section of the heating and ventilation control board and power for critical equipment such as radiation monitoring systems, the SFP level monitoring system, and the annunciator system through lighting panels 3L4 and 3LS. When Unit 3 was operating, this section also provided 480-volt AC power to Valve Control Center No.1 (VCC-1),

the emergency gland seal exhauster, the emergency makeup pump, Pfdraulic Pump No. 2, and Core Spray Pump No.1. These loads were disconnected during the transition to SAFSTOR. With the elimination of VCC-1, the emergency gland seal exhauster, the emergency makeup pump, Hydraulic Pump No. 2, and Core Spray Pump No.1, the emergency section of MCC-10 is lightly loaded and has sufficient additional capacity to provide normal source AC power to Power Panel No.1.

Safety Evaluation Summary:

The basic source of power to Power Panel No.1 did not change since it will normally be supplied from the 60-kV bus through House Transformer No. 2 and Load Center Transformer No. 5, v hich powers both the normai and emergency sections of MCC-10. The electricalload requirements were evaluated and found to be within the capability of the emergency section of MCC-10. This modification provided a backup power supply to ensure that critical equipment will remain operational during a loss of offsite power.

2. DCP M-00401 DCN HB3-SM-401 Add Discharoe Capacity to Caisson Sump - Phase i This modification increased the capacity of the caisson sump pump system. It also enhanced the reliability of the system to prevent flooding of the caisson.

The modifications included:

. Adding a new submersible pump to the caisson sump pump system.

. Adding a power supply for the rnotor cf the new submersible pump.

. Modifying the caisson sump pump piping and adding a rer.irculation flow path.

. Redesigning the control logic to minimize the start /stop frequer.cy of the caisson sump pumps.

This modification increased the capacity of the caisson sump pump system from approximately 10 gallons / minute to approximately 30 gallons / minute. It increased the reliability and flexibility of the system since each pump can be removed from service for maintenance without affecting the other pump. This 2

modification also provided for future expansion of the pumping systerr,,if required.

Safety Evaluation Summary:

There were no potential safety evaluation issues associated with this modification. Adding a pump and recirculation flow path only increased the capacity, reliability and flexibility of the pumping system, and its ability to handle the increases in groundwater inleakage to the caisson.

None of the flow paths or specifications for the caisson sump pump system as described in the Technical Specifications, SAFSTOR Decommissioning Plan, or any other license basis document was changed. The only license basis document change that will be necessary will be an editorial chanae to the SAFSTOR Decommissioning Plan; " pump" will be changed to " pumps" in Table 3-1 (page 3-41) and Section 3.2.3.3 (page 3-17).

3. SERA HB3-001 Remove No.1 and No. 2 Core Sorav Pumos and Associated Picina This modification removed the No.1 and No. 2 core spray pumps and associated suction and discharge piping at the foot elevation.

Safety Emluation Summary:

Because this equipment was in layup, no longer in service, and did not interface with any of the active systems required to maintain Unit 3 in SAFSTOR, there were no potential safety evaluation issues associated with this modification.

4. SERA HB3-002 Remove Scram Dump Tank and Associated Pipina This modification removed the scram dump tank and associated piping in the REDT room of the access shaft at the foot elevation.

Safety Evaluation Summary:

Because this equipment was in layup, no longer in service, and did not interface with any of the active systems required to maintain Unit 3 in SAFSTOR, there were no potential safety evaluation issues associated with this modification.

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l S. SERA HB3-003 Remove Reactor Head O-rino Leak Detection Instrumentation and Drvwell Lower Head Water Detector / Drain Instrumentation This modification removed the reactor head inner O-ring detection instrumentation and the drywell lower head water detection and drain instrumentation.

Safety Evmustion Summary:

Because this equipment was in layup, no longer in service, and did not interface with any of the active systems required to maintain Unit 3 in SAFSTOR, there were no potential safety evaluation issues associated with this modification.

PROCEDURE CHANGES Listed below are the changes made to procedures or new procedures in 1996 as described in ti e SAFSTOR Decommissioning Plan, along w'tn a brief description of the changes and a summarv of the safety evaluations. More complete records of these procedure changes have been reviewed by the HBPP PSRC, and the changes were determined not to involve an unreviewed safety question or require a change to the HBPP Technical Specifications.

1. TP 2/22/96 Gravity Feed Test - Demineralized Water Tank to Spent Fuel Pool During the 1994 NRC team inspection, it was noted that, in the event of a failure of the demineralized water pump, gravity feed of the demineralized water tank to the SFP was possible, but this design feature had not been tested. Testing to establish the gravity feed flow rate would provide confidence that gravity makeup to the SFP is functional.

This temporary procedure evaluated the capability of the demineralized water system to supply water to the SFP via gravity feed in the event that the demineralized water pump becomes inoperable and makeup water is required for the SFP. To cerform the test, the demineralized water pump was secured, and the priming water valve to the suction of the SFP pumps was opened to determine the gravity flow rate.

Safety Evaluation Summary:

I While the procedure was being performed, the demineralized water pump was out of service. When the demineralized water system is not available, emergency makeup to maintain adequate shielding of the spent fuelis provided 4

i from the fire system, which was not affected by the performance of this procedure.

2. Radwaste Shioment. March 25.1996 Although there wtue no changes to plant procedures associated with this radwaste shipment of March 25,1996, a revision to a procedure described in the SAFSTOR Decommissioning Plan was required. This shipment included 14 drums of re. waste system spent certridge-type filters and one drum of SFP spent cartridge-type filters. The SAFSTOR Decommissioning Plan, Section 4.4.5.2," Waste Processing and Disposal," states:

Spent cartridge-type filters (and filter crud) will be packaged in 55-gallon (or similar) drums and stored in a shielded area. The contents of the drums will be sampled and analyzed to classify the wastes. When a sufficient quantity of wastes has accumulated, the wastes will be processed by solidification / encapsulation (by an outside contractor with portable equipment) in accordance with current regulations, followed by shipment in appropriate shipping containers to the burial sito.

'Nhen this particular section of the SAFSTOR Decommissioning Plan was written, it was assumed, based on operating cxperience, that these spent filters would contain radioactivity such that tney would be classified as Class B or Class C waste and mquire solidification or encapsulation for transportation or burial. It has been found, however, that the cartridge-type filters that have been generated during the SAFSTOR period have much loiner levels of radioactivity than anticipated. The filters are classified as Class A waste and, therefore, do not require solidification or encapsulation to be in accordance with the current regulations for shipment or burial. Dose rates for these filters were anticipated to be on the order of 1 to 10 Rihr when the SAFSTOR Decommissioning Plan was written, but these filters have bean found to have a dose rate of 3 to 4 mR/hr for the radwaste filters and approximately 50 mR/hr for the SFP filters.

Safety Evaluation Summary:

There were no potential safety evaluation issues associated with this change.

The lack of solidification / encapsulation of the spent cartridge-type filters did not affect any accident analyses or create any credible new accidents during SAFSTOR. Although Section 4.4.5.2 of the SAFSTOR Decommissioning Plan states that spent cartridge-type filters are to be processed by solidification or encapsulation, current regulations do not require solidification or encapsulation of the filterc for transportation or burial, provided they are Class A per 10 CFR 61. The level of radioactivity contained in these filters was far below the levels that were assumed for the filters when the SAFSTOR Decommissioning Plan was written. Solidification or encapsulation of these filters would have had 5

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the potential to increase the occupational dose received by those radiation workers who would have been required to perform the unnecessary processing and handling of the filters.

3. TP 9/13/96 Caisson Ground Water Inteakaae Inspection This procedure provided instructions to investigate which sector of the caisson supplied the greatest amount of ground water in-leakage and to inspect a portion of the interface of the caisson ww and tremie concrete plug at the bottom of the caisson. This activity was performed to try to minimize the work necessary to repair the in-leakage.

The procedure for investigatior, of in-leakage in the four distinct drainage areas provided plans for the removal of portions of the concrete finish flou and

[ drainage rock at the foot elevation, inspection and cleaning of the six 3-inch L drains between caisson sections, testing for water flow, and repair of the floor.

This work was conducted in a controlled manner to avoid the possibility of

( increasing flows that may have resulted in exceeding the capacity of the caisson i

sump pump, to prevent contamination of the groundwater entering the caisson sump, and to assure adequate depressurization of the drainage rock layer prior to remeving sections of the fioor.

Safety Evaluation Summary:

Potential safety evaluation issues included an increased flow of groundwater that would exceed the capacity of the radwaste processing system, and radioactive contamination of the caisson sump water and subsequent encontrolled release of radioactive liquid to the environment. The procedure was written to be performed in a controlled manner to preclude the possibility of increased groundwater flows and sump contamination, in the unlikely event that grmindwater inleakage flow were to increase beyond the capacity of the radwaste processing system, a contingency plan was developed to ensure that

_ groundwater inleakage beyond the radwaste processing system capacity cotild be effectively handled. Even if all contingencies were to fail, the concentrations and release of radioactivity in the caisson were analyzed, and they are bounded by a previously analyzed accident, the rupture of the spent fuel pool.

1996 TESTS AND EXPERIMENTS No tests or experiments were performed duririg the reporting period that are not described in the SAFSTOF Decommisciening Plan.

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