ML20117K467

Safety Evaluation Supporting Amends 113 & 111 to Licenses DPR-80 & DPR-82,respectively

ML20117K467
Person / Time
Site:	Diablo Canyon
Issue date:	05/28/1996
From:	NRC (Affiliation Not Assigned)
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ML20117K461	List: ML20117K467
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NUDOCS 9606110283
Download: ML20117K467 (4)

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UNITED STATES g

j NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 2065!M001 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATFD TO AMENDMENT NO. 113 TO FACILITY OPERATING LICENSE NO. DPR-80 AND AMENDMENT NO. 111 TO FACILITY OPERATING LICENSE NO. DPR-82 PACIFIC GAS AND ELECTRIC COMPANY DIABLO CANYON NUCLEAR POWER PLANT. UNITS 1 AND 2 DOCKET NOS. 50-275 AND 50-323 j

1.0 INTRODUCTION

By application dated April 3,1996, Pacific Gas and Electric Company (or the L

licensee) requested changes to the Technical Specifications (Appendix A to Facility Operating License Nos. DPR-80 and DPR-82) for the Diablo Canyon 4

Nuclear Power Plant (DCPP), Units 1 and 2.

The proposed changes revise the combined Technical Specifications (TS) for the Diablo Canyon Nuclear Power Plant, Unit Nos. I and 2 to revise Technical Specifications 3/4.7.5, " Control Room Ventilation System;" 3/4.7.6, " Auxiliary Building Safeguards Air Filtration System;" and 3/4.9.12, " Fuel Handling Building Ventilation System" to clarify the testing methodology utilized by PG&E to determine the operability of:the charcoal and high efficiency particulate air (HEPA) filters in the engineering safeguards features (ESF) air handling units at the Diablo Canyon Nuclear Power Plant (DCPP).

2.0 EVALUATION 2.1 Charcoal Testing The current DCPP TS requirements for surveillance testing of charcoal samples from the ESF ventilation systems do not accurately reflect the actual testing being performed in the industry to determine methyl iodide penetration.

Rather than performing the surveillance to meet older industry standards and regulatory guidance, the licensee proposed to modify the TS to reflect the current testing being performed.

The proposed amendment changes the testing requirements in the TS used to determine the operability of the charcoal in the ESF air handling units. The charcoal is provided to remove iodine from the air as it passes through the e

air handling units.

There are no changes to the physical design or operation of the facility.

Updated Safety Analysis Report (USAR) design basis are not affected.

The guidance in Regulatory Guide (RG) 1.52, " Design, Testing, and Maintenance Criteria for Post Accident Engineered-Safety-Feature Atmosphere Cleanup System Air Filtration and Adsorption Units of Light-Water-Cooled Nuclear Power Plants, Revision 2" and American National Standards Institute (ANSI) N509-9606110283 960528 i

PDR ADOCK 05000275 p

PDR

• 1976, " Nuclear Power Plant Air Cleaning Units and Components," presently forms the licensing basis test requirements. The current TS references Regulatory i

Position C.6.a of Regulatory Guide 1.52, Revision 2, March 1978, which j

requires testing in accordance with ANSI N509-1976, which requires that the testing be performed at 80*C.

The essential elements of the proposed TS change are those outlined by RG 1.52, Revision 2 and ANSI N509-1980 which refers to ASTM D 3803-1979,

" Standard Test Methods for Radiation Testing of Nuclear-Grade Gas-Phase Adsorbents." ASTM D 3803-1979 is updated guidance based on RDT M16-1T, " Gas Phase Adsorbents for Trapping Radioactive Iodine and Iodine Components."

The quantity of water retained by charcoal (carbon) is dependent on temperature.

Generally, the higher the temperature the less water retained.

The water retained by the carbon decreases the efficiency of the carbon to adsorb other contaminants. At 25'C and 95 percent relative humidity (RH),

carbon will retain about 40 weight percent water. At 80*C and 95 percent RH, carbon retains only about 2 to 3 weight percent water.

During an accident, the charcoal adsorber banks would not experience that high a temperature, therefore testing at higher temperatures produces non-conservative results.

ASTM D 3803-1979 specifies a test temperature of 30'C instead of 25'C for the pre-load and post-load sweep temperatures.

There is little difference in the adsorption behavior of carbon between these two temperatures. The 25'C parameter is more conservative.

Pre-test humidity equilibration is achieved by sweeping air of the appropriate humidity through the test carbon. This condition is for testing new carbon and until 1977 it also was applied for testing used carbon.

In 1977, RDT M16-1T-1977 was released stating that for testing used carbon, "the material shall not be pre-equilibrated before testing." NUREG/CR-0771, " Effects of Weathering on Impregnated Charcoal Performance," May 10, 1979, provides a basis by stating that, "it is thought that the elimination of the pre-humidification is a better simulation of accident conditions since a carbon filter must be ready at all times...."

It also states that, "several investigators do not recommend any pre-treatment (of the carbon) in order to prevent a partial regeneration of the carbon which would increase the measured trapping efficiency." Therefore, by the release of the ASTM D 3803-1979 standard, it was established that the better test method was not to pre-equilibrate the humidity of the carbon.

The present TS reference to N509-1976 (RDT M16-1T) requires the carbon tc be equilibrated to 25'C and 70 percent RH.

The methyl iodide test medium would then be instantaneously introduced at 80*C.

Carbon testing is not performed this way because this would cause condensation to form on the carbon (the dew point temperature of the test medium at these conditions is approximately 71*C.) Condensation on the carbon sample itself (" wetting the bed") results in the test being invalid. This is supported by paragraph 12.41. of ASTM D 3803-1979 which states with respect to relative humidity of the test medium that,

" tests at saturation or above give very erratic results." Because of this, the testing standards after 1976 (i.e., RDT M16-1T-1977, ASTM D 3803-1979, j

' N509-1980), have been changed to include pre-test thermal equilibration at the test temperature.

The proposed TS change to N510-1989, Appendix B, for the 30*C and 95 percent RH methyl iodine test is considered by the Idaho National Engineering Laboratory and the NRC to be the most reliable test method. ASTM D 3803-1989, Annex A5 allows for humidity testing of the charcoal at various operating conditions as required by the facility, however, the testing temperature will be 30*C in all cases.

For the control room and auxiliary building ventilation system, the humidity of the exhaust air is controlled to 70 percent RH maximum. Therefore, the charcoal samples for the control room and auxiliary building are to be tested at 70 percent RH.

The post-test sweep of the carbon is performed to evaluate the ability of the carbon to hold the adsorbate once it is captured.

The current TS test specifies a two hour test at 25'C.

The requested changes revise TS 3/4.7.5, " Control Room Ventilation System;"

3/4.7.6, " Auxiliary Building Safeguards Air Filtration System;" and 3/4.9.12,

" Fuel Handling Building Ventilation System", and the associated TS Bases relating to surveillance requirements for charcoal filter laboratory testing, such that existing flawed test methodology in the TS will reflect the currently utilized acceptable test methodology in accordance with industry standards. The staff has evaluated this change and concludes that the testing methodology proposed by the licensee adequately demonstrates the operability

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of the air handling units, and is therefore acceptable.

2.2 Other Testing The current DCPP TS requires that other filter testing, such as filter visual inspections and in-place penetration and bypass leakage testing of HEPA filters and adsorber banks, also be performed in accordance with RG 1.52.

RG 1.52 references ANSI N510-1975, and describes the requirements for the required testing.

The requested changes revise TS 3/4.7.5, " Control Room Ventilation System;"

3/4.7.6, " Auxiliary Building Safeguards Air Filtration System;" and 3/4.9.12,

" Fuel Handling Building Ventilation System", relating to surveillance requirements for filter visual inspections, in-place penetration and bypass leakage testing of HEPA filters and adsorber banks. The proposed TS will require that testing be performed in accordance with ANSI N510-1980, which encompasses the testing required by N510-1975. The staff has evaluated this change and concludes that the testing methodology proposed by the licensee adequately demonstrates the operability of the air handling ur.its, and is therefore acceptable.

3.0 STATE CONSULTATION

In accordance with the Commission's regulations, the California State official was notified of the proposed issuance of the amendments.

The State official had no comments.

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4.0 ENVIRONMENTAL CONSIDERATION

These amendments change surveillance requirements. The NRC staff has determined that the amendments involve no significant increase in the amounts, and no significant change in the types, of any effluents that may be released offsite, and that there is no significant increase in individual or cumulative occupational radiation exposure. The Commission has previously issued a proposed finding that the amendments involve no significant hazards consideration, and there has been no public comment on such finding (61 FR 18173). Accordingly, the amendments meet the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9).

Pursuant to 10 CFR 51.22(b) no environmental impact statemeat or environmental assessment need be prepared in connection with the issuance of the amendments.

5.0 CONCLUSION

The Commission has concluded, based on the considerations discussed above, that (1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, (2) such activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendments will not be inimical to the common defense and security or to the health and safety of the public.

Principal Contributor:

S. Bloom Date:

May 28, 1996 4