HBL-87-086, Annual Rept of Design Changes,1986

Annual Rept of Design Changes,1986

ML20234C629
Person / Time
Site:	Humboldt Bay
Issue date:	12/29/1987
From:	Shiffer J PACIFIC GAS & ELECTRIC CO.
To:
References
HBL-87-086, HBL-87-86, NUDOCS 8801060278
Download: ML20234C629 (5)

Text

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r PACIFIC GAS AND E LE C T RI C C O M PANY i

bD'NE l 77 BEALE STREET . SAN FR ANCISCO, C ALIFORNI A 94106 * (415) 781 4211 . TWX 910 372-0587 JAVCS O. SMIFFER NUCLEA R EN RAf TON .

December 29, 1987 PG&E Letter No.: HBL-87-086 U. S. Nuclear Regulatory Commission ATTH: Document Control Desk Hashington D.C. 20555 l

Re: Docket No. 50-133, OL-DPR-7 Humboldt Bay Power Plant Unit 3 Annual Report of Design Changes During 1986

Dear Mr. Martin:

t, Pursuant to 10 CFR 50.59, enclosed is the annual report containing a summary of the. modifications made to Humboldt Bay Power Plant Unit 3 during 1986.

Complete modification records, including written safety evaluations, are maintained at Humboldt Bay Power Plant. The Plant Staff Review Committee has determined that these modifications made under the provisions of 10 CFR 50.59 do not involve unreviewed safety questions or changes to the plant Technical Specifications.

Please acknowledge receipt of.the attached. report on'the enclosed copy of this letter and return it in the enclosed addressed envelope.

Sincerely, i

Enclosure i cc: P. B. Erickson J. B. Martin <

Humboldt Service List Humboldt Distribution l l

1814S/0053K/PLP/1219

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DR ADOCK 0500 3

1 PG&2 Letter No.: HBL-87-086 ENCLOSURE HUMBOLDT BAY POWER PLANT UNIT 3 ANNUAL REPORT OF DESIGN CHANGES FOR 1986 1 1

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HUMBOLDT EAY POWER PLANT UNIT 3 l

ANNUAL REPORT OF DESIGN CHANGES FOR 1986 As a holder of operating license DPR-7, Pacific Gas and Electric Company is required by 10 CFR 50.59(b) to submit an annual report to the Nuclear Regulatory Commission, Region V Office, summarizing the changes made to Humboldt Bay Power Plant Unit 3 during the previous year. This report is intended to satisfy that requirement.

Listed below by number are all design changes made to Unit 3 in 1986, along with brief descriptions of the changes and summaries of the safety evaluations. More complete records of these design changes have been reviewed by the Plant Staff Review Committee and determined not to involve either unreviewed safety questions or changes to the plant Technical Specifications.

1. DCR HB3-0-SH-121. Reroutino of Treated Haste Discharae Line The treated waste discharge line is used to discharge processed water from the plant radwaste system to Humboldt Bay. As originally designed, this line ran from the radwaste treatment building to the Unit 3 circulating water line, which discharged into the outfall canal leading to the bay. Because Unit 3 is not operating, there is no longer a circulating water flow in the line to carry the waste into the outfall canal. A new treated waste discharge line was installed from the radwaste treatment building to the circulating water outfall headworks for Units 1 and 2. This will allow the treated waste to be discharged into the circulating water flow from Unit 1 or 2.

Safety Evaluation Summary The new treated waste discharge line was designed and constructed to comply with the recommendations stated in IE Circular 80-18. The standards of construction for the new line are at least equal to those for the original line. The ultimate discharge point to the bay remains the same. No new conditions were created. The Technical Specifications require that the treated waste discharge be diluted; the new discharge line will adequately perform this function.

2. DCR HB3-0-SC-167. Radwaste Buildina Enclosure A new building has been constructed over the plant's radwaste facility.

This new building is a pre-engineered metal type which fully encloses the radwaste treatment building and radwaste tankage area.

Safety Evaluation Summaty The design of the new building has been evaluated regarding compliance with 10 CFR 20, 10 CFR 100, 40 CFR 40. NRC Generic Letter 81-38, and IE Circular 80-18. The new building enhances control of gaseous discharges from the radwaste facility, reduces the amount of water that must be processed due to rain falling in the radwaste tankage area, and reduces 1814S

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i degradation of radwaste handling equipment. caused by exposure to the weather. The possibility of a building collapse damaging the radwaste system has been created. However, the failure of the radwaste system has  ;

previously been analyzed considering the most severe scenario which has 1 shown that the consequences are not increased. l l

l 3. DCR HB3-0-SH-172. Radwaste Concentrator Modifications l The original radwaste concentrator system design provided for the concentrator feed pump to be located outside the concentrator room and for the discharge from the concentrator to be routed to the radwaste sump, then pumped to radwaste tankage. To better control the spread of contamination in the.radwaste building, reduce the amount of personnel radiation exposure during operation of the system, and minimize the possibility of accidental release, the following modifications were made to the concentrator system:

a. The concentrator feed pump was. relocated into the concentrator room.

b. A pump was installed in the concentrator room to pump the concentrator discharge directly to radwaste tankage. j l

c. The heating steam drips were routed to the radwaste tankage area sump, from which they are pumped to radwaste tankage, j 1

In addition to the concentrator system modifications, another change to the radwaste system was made. This involved the installation of a check i valve in the line connecting the radwaste sump pump to the caisson sump  !

pump. This was done to remove the possibility of a valving error ,

allowing the contents of the radwaste sump to be pumped to the outfall j canal.

Safety Evaluation Summary The original piping standards were followed in designing and constructing j these modifications. The reliability of the radwaste system will not be q affected. The possibility of an uncontrolled release of radioactive a' material is reduced by pumping the concentrator discharge directly to radwaste tankage, routing the heating steam drips to the radwaste tankage ..

area sump, and installing a check valve in the'radwaste sump pump line. I Relocating the concentrator feed pump into the concentrator room will reduce radiation exposure to operating personnel. .

4. DCR HB3-0-SH-185. Modifications to TBDT Drain and Vent Pioina During cleaning operations the turbine building drain tank (TBDT) drain  ;

line became plugged. The line could not be cleared by back-flushing because there was no hose connection on the drain line and also because  !

it was connected to the TBDT vent, which prevented the buildup of sufficient pressure to clear the plug. To remedy this situation, a hose connection was installed on the end of the drain line where it emptied '

into a scupper, and a valve was installed between the drain line and the TBDT vent.

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Safety Evaluation Summary Conditions are not significantly affected by this change. The TBDT can still be drained with the hose connection in place, and the valve that was installed will normally be kept open to maintain the connection between the drain line and the TBDT vent.

5. DCR HB3-0-SM-194. Modification to Unit 3 South Yard Drains Repaving of the yard around Unit 3 required that the elevations of the yard drain sumps and catch basins be lowered slightly to maintain good drainage. All changes in elevation were less than 1 inch.

Safety Evaluation Summary The slight changes in elevation of the sumps and catch basins will not affect the ability of the drainage system to remove water from the yard.

6. DCR HB3-0-SM-195. Reoairs to CHT 1 and 2 While concentrated waste tanks (CWT) I and 2 were being cleaned, it was discovered that the temperature probe ports and the lines that were used to provide tank level indication were badly corroded. The temperature probe ports were removed, and the holes created were repaired. The level indicating lines were cut off and capped, and the lines and associated instrumentation were removed from the CHT vault.

Safetv Evaluation Summary The repairs meet the recommendations of IE Circular 80-18 and do not degr<ade the reliability of the tanks. Both the temperature and level measuring systems were removed from the tanks. It is not expected that the CHTs will be used again; therefore, these measurements will not be necessary. If it does become necessary to measure the level and temperature of thEse tanks, it Can be easily accomplished by the use of instrumentation lowered through the tank's roof manway. 2

7. DCR HB3-0-Sp-197. Placement of Boral Poison Channels Around SDent Fuel Current plans call for the spent fuel now on site to remain for an extended period of time. In order to minimize the possibility of accidental criticality in the spent fuel pool, each fuel bundle has been encased in a can made of boral.

4 Safety Evaluation _ Summary The boral cans in which the fuel bundles have been placed act as neutron absorbers which will prevent criticality in the spent fuel pool even if the fuel racks are severely damaged. Since the boral cans reduce the potential for criticality and are compatible with the spent fuel pool environment, installation of the boral cans has no adverse effect on the fuel or the spent fuel pool. Therefore, the boral cans have no adverse impact on the safety of the plant.

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