ML20076E880

Responds to NRC 830413 Order Re Environ Qualification of safety-related Electrical Equipment,Per 10CFR50.49.Environ Qualification Records Audit Will Be Completed by 831231

ML20076E880
Person / Time
Site:	Fort Saint Vrain
Issue date:	05/17/1983
From:	Lee O PUBLIC SERVICE CO. OF COLORADO
To:	Jay Collins NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
References
REF-SSINS-6820 IEB-79-01B, IEB-79-1B, P-83178, TAC-42527, NUDOCS 8306010335
Download: ML20076E880 (8)

Text

..- - . ____

1 l

PUBLIC SERVICE COMPANY OF COLORADO P. O. B o x e4O DENVER, COLORADO 80201 I

' May 17, 1983 Fort St. Vrain OSCAR R. LEE Unit No. I P-83178 i

I Hr. John T. Collins Regional Administrator 7 ]@ g ]g g  ;

Region IV Nuclear Regulatory Commission MAY 2 61983 611 Ryan Plaza Drive Suite 1000 Arlington, Texas 76011 -

_Wl Docket No. 50-267

SUBJECT:

10CFR50.49 Environmental Qualification of Safety Related Electrical Equipment

Dear Mr. Collins:

The following is Public Service Company of Colorado's (PSC) response to the NRC's April 13, 1983 order concerning environmental qualification of safety related electrical equipment as required by 10CFR50.49.

i Summary of Previous Submittals PSC previously submitted several letters concerning environmental qualification of safety related electrical equipment, either as i follow up to meetings between PSC and NRC, or in response to IE-Bulletin 79-018.

The following summarizes those previous submittals.

P-77137 June 15, 1977 (Millen to Denise)

1. Sumarized PSC's Seismic and Environmental Qualification Program.

2. Summarized review on seismic qualifications of Class I equipment and environmental qualifications of safe shutdown equipment.

.s D C306010335 030517 l PDR ADOCK 05000267 ,

- h p  ;PDR - -

i

~

... --.-._-.a. . . - . - - - - . : - _ - .-.. - - -.- - - - _ , -

P-83178 Page 2

3. Established corrective action for unqualified Class I equipment.

P-79124 June 12,1979 (Fuller to Seyfrit)

1. Determined the matter of environmental qualification closed with

' Amendment 18 to the Facility Operating Licensa DPR-34.

2. Listed relevant correspondence between PSC and the NRC during the review of the Fort St. Vrain Environmental Qualification Program by NRC-NRR and NRC-I&E Re (Attachment "A" to P-79124)gion IV with PSC between 1977 and 1978 P-80051 March 18,1980 (Swart to Seyfrit)

1. Discussed steam line accidents including report entitled

" Environmental Temperatures in the Vicinity of the Rupture Point of Steam Lines for Fort St. Vrain Equipment Qualification."

(Attachment "D" to P-80051).

2. Discussed plant equipment numbering. (Attachment "B" to P-80051).

3. Discussed areas not applicable to a HTGR, including radiological details of DBA#1. (Attachment "C" to P-80051).

4. Included computer programming similar to IE-79-01B Enclosure 2.

(Attachment "A" to P-80051).

P-80078 April 11,1980 (Swart to Seyfrit)

1. Summarized items from March 18, 1980 submittal that were previously accepted by the NRC (Attachments "C" and "D" to P-80051).

2. Updated computer lists (Attachment "A" to P-80078) and Component Evaluation Work Sheets (Enclosure 3 to P-80078).

P-80090 April 18,1980 (Swart to Seyfrit)

1. Updated ccmputer lists (Attachment "A" to P-80090) and Component Evaluation Work Sheets (Enclosure 3 to P-80090).

2. Finalized Emergency Procedures review.

3. Clarification of Component Evaluation Work Sheets.

P-80350 October 3,1980 (Fuller to Seyfrit)

1. Commitment. to completion of environmental qualification records review.

'. , p 7^

> ;l - U.

P-83178 .

-g s Page 3 l

. + -

Commitment- to completion' of enviVbnmental testing of generic

~

2.

s l

l te,ms . , . ,

3. Finalized computer .' lists (Attachhent'"A" to P-80350) and Component' Evaluation' Work Sheets (Enclosure 3 to P-80350).

4. Discussion off areas not applicable to aIHTGR, including aging.

J These previous submittals have been in accordance with the provisions of IE-79-018, exceptions noted. They are also in accordance with the provisions, of 10CFR50.49.

. Identification of FSV Electric Equipment which Requires Environmental Qua?ification ,

o a , ,' '

Ths- rules of' 10CFR50.49 define the safety functions of- those equipment iteins to be considered important to safety and for which, environmental qualification is to be addressed. 10CFR50.49'also~

provides an exemption from environmental qualification for~ those items important to safety which are only exposed to normal operating environments (including environments due to anticipated operational

, eccurrences),

c The fort St. Vrain Nuclear Generating Station is designed for two acciderttst which create operating environment conditions significantly mcre. severe than the normal operating environment. These are the High Energy. Line Break and the Reactor Coolant System Depressurizaticco ,

The Forlt St. Vrain Nuclear Generating Station is also designed for performance of the required safety functions in case of earthquakes and torandoas. Equipment which has a safety, function under those condit! ions is designed and qualified to the requirements applicable to Class I items as specified in the FSAR. The remaining equipment is Class II.

~

Only Class I equipment is required to perform a sofety function in j

J the event of a High Energy Line Break.

In the case of Reactor Coolant System Depressurization, Class II

, items', together with Class I items, are required to perform safety functions. However, only ; Class I items are exposed to the abnormal accident environment ' conditions which, for environmental

~ qualification purposes,' are less stringent than the High Energy Line

, Break environment conditions. The Class II item required to operate are located outside the reactor luilding, and are only exposed to the nemal operating environment.

i

y E

J #

4 p~

t

P-83178 Page 4 Therefore, only the Class I electric equipment items require consideration of environmental qualification under the scope of 10CFR50.49. The applicable environmental qualification requirements for the Class I electrical equipn.M vary depending on item location and function. In accordance with 10CFR50.49 paragraph c(fii), Class I items not exposed to a severe environment do not require environmental qualification. Class I items required for safe shutdown (Safe Shutdown equipment) that are exposed to a High Energy Line Break (HELB) are required to be qualified for that environment.

Failure of Class II equipment cannot prevent Class I equipment from performing their safety functions. Any component that has an affect on a Class I function is itself defined as Class I. Special designations are assigned to components that must either maintain system pressure boundary or electrical circuit continuity. Such components are qualified accordingly.

Class I electrical equipment may be identified by several methods.

The safety related components list (SR-6-2) indicates which tagged items are Class I. Special reports that list the seismic and environmental qualification records of Class I components are also generated by SR-6-2.

Tagged items may also be identifiet; by special symbols on plant Process and Instrumentation (P&I) Diagrams, Instrumentation and Control (IC) diagrams, and Instrumentation Block (IB) diagrams.

P&I's also show Class I process lines and indicate Class I boundaries.

Essential cables are ir.dicated on electrical schematic diagrams.

Such schematics are identified by a "ESS BxLy" (Essential Bus x Loop y) designation. PSC is currently engaged in a project that will highlight specific Safe Shutdown circuitry on schematic diagrams.

This will clarify which components must function and which nust maintain electrical circuit continuity.

Areas Not Applicable to a HTGR As we have previously indicated in submittals in response to IE-Bulletin-79-018, many areas of concern listed in 10CFR50.49 do not apply to the Fort St. Vrain HTGR. These areas were previously discussed in our March 18, 1980 submittal P-80051, and our October 3, 1980 submittal P-80350. For convenience, similar discussions are repeated here.

Areas not applicable to a HTGR:

1. Pressure: The FSV HTGR does not have a containment building; therefore, there is no ambient pressure buildup.

l

2. Relative Humidity: _ For the same reason discussed above for pressure, relative humidity is not a concern at FSV.

1 P-83178 Page 5

3. Chemical Spray: Chemical sprays are not utilized at FSV.

4. Radiation: There are no radiological concerns associated with a HELB at FSV. Our October 3,1980 submittal, P-80350, concludes that the reactor building will be accessible for short term operations following DBA#1. It further concludes that the accumulated doses incurred during DBA#1 would have no operational affect on equipment in the Reactor Building.

5. Submergence: Water is not used for shutdown or emergency core spray, thus, submergence does not apply.

6. Replacement Parts: Since standards are based on Light Water Reactor Technology, PSC believes there are " sound reasons to the contrary" for requiring replacement parts for FSV to be purchased to the requirements of 10CFR50.49. Purchasing of spare parts must be made in accordance with requirements consistent with criteria established during the licensing of the plant.

7. Aging: PSC has concluded, in our October 3, 1980 submittal, P-80350, that we have an adequate basis for taking exception to the aging requirenents. This conclusion is based on the following arguments:

Fort St. Vrain does not utilize a conventional containment building. Thus, long tem environmental conditions are not present.

Fort St. Vrain does not utilize a special cooling system. The nomal reactor cooling system is also the emergency cooling sytem. The advantage here lies in the fact that the safety system is operated in the course of nomal operations. This eliminates the question of the reliability of infrequently used safety systems. Maintenance is perfomed as required to insure continued reliable operation.

Since the FSV HELB is short term in nature, and radiological concerns minimal, access to any location in the plant is possible shortly following an accident.

Redundant Forced Circulation Cooling equipment is physically located in different areas to preclude failures from a single accident. Additional assurance is provided by valves with manual overrides and/or " designed failure mcdes" to insure their proper operation following an accident.

The availability of access coupled with the time available to restore Forced Circulation Cooling provides desirable flexibility in terms of manual overrides and maintenance.

The PCRV Liner Cooling System has redundancy and physical separation to preclude failure from a single accident.

P-83178 Page 6 "In the unlikely event that the normal power supply to the PCRV Liner Cooling system fails, the Alternate Cooling Method (ACM) is available. The controls and cabling for this system are physically separated from normal emergency equipment.

Furthermore, the equipment and controls for ACM are outside HELB environments. (Cables for two depressurization systems are in the Reactor Building HELB environment. Manual operators outside of the HELB environment have subsequently been added)."

Because of the above reasons, Fort St. Vrain has adequate means of protecting the health and safety of the public, should " aged" equipment fail during a HELB.

Current Status of Environmental Qualification Program PSC is currently performing an audit of our environmental qualification records. This effort consists of; identifying Safe Shutdown equipment in HELB environments based on the safety related components list (SR-6-2), verifying that all electrical components required for the above equipment to function are qualifed for their respective environments, and establishing a complete and auditable qualification file.

We are also currently involved in an effort to highlight Safe

! Shutdown electrical equipment on electrical schematic diaorams.

We are developing a program to resolve the requirements of Post Accident Monitoring Instrumentation as established by Reg. Guide 1.97. PSC has had to interpret the guidance provided by RG 1.97 to determine its affect on HTGRs. Once this program determines the requirements for this instrumentation, environmental qualification may be implemented.

Schedule for Completion The current audit of environmental qualification records is approximately 70% complete. We expect to complete the audit, as it applies to equipment in a HELB environment, by no later than December 31, 1983.

The audit so far has uncovered two component model types, comprising a total of three actual plant items, that have not been fully tested for their expected environmental conditions. These items, all valve actuators, will be subject to steam line simulation tests by no later than August 31, 1983.

P-83178 Page 7 Because these actuators are similar to other actuators that have been qualified by tests in the past, we are confident that they will also pass their respective steam line rupture simulation tests. Also these actuators all have " designed failure modes", i.e. they fail in the safe direction. Furthermore, these actuators have manual overrides, i.e. handwheels, that allow them to be manually operated following an accident.

Because of the above reasons, we do not believe that we are in any manner endangering the health and safety of the public by operating with these valve actuators not fully tested.

Identification of HELB environment, Safe Shutdown equipment on electrical schematic diagrams will be marked up and released into our drawing system by no later than December 31, 1983.

PSC previously committed, in our April 14, 1983 letter P-83147, to a date of October 31, 1984 for submitting a report on the Post Accident Monitoring System as required by RG 1.97 and NRC Generic Letter 82-33. In conjunction with this effort, we will also define the environmental qualification requirements of accident instrumentation.

We expect the monitoring equipment to be fully qualified by December 31, 1984.

Summary of Response to 10CFR50.49 PSC has conducted several audits of our environmental qualification records in the past and is currently conducting another. We expect our current audit to be complete by no later than December 31, 1983.

In conjunction with this effort, we are establishing a complete and fully auditable record system.

We have made several submittals in the past, either in response to IE-79-01B or as follow up to meetings between PSC and the NRC. These submittals comply with the requirements of 10CFR50.49.

Class II electrical equipment has no affect on the perfonnance of Class I electrical equipment. Special designations are given to instruments that must either maintain system pressure boundary or electrical circuit continuity. Class I components may currently be identified by the Safety Related Components list (SR-6-2),P&I diagrams, IC diagrams, and on IB diagrams. Such components will, in the future, be identifiable on electrical schematic diagrams.

Most of the requirements of 10CFR50.49 do not apply to the FSV HTGR.

These include aging, radiation, pressure, relative humidity, chemical sprays, submergence and replacement parts.

P-83178 Page 8 Our audit has uncovered three valve actuators that do not have complete qualificatiot testing. Because these actuators are similar to models previously qualified, because they have " designed failure modes" and because tSey all have handwheels to override any possible failures, we do not, believe we are endangering the health and safety of the public.

Our post accident monitoring equipment is currently under review and will be qualified by December 31, 1984.

As we continue to implement the various phases of our projects, or if any changes to the commitments are required, the staff will be advised.

Very truly yours,

[

0. R. Lee, Vice President Electric Production ORL/sm:pa

____ _ _ - _ _ _ . _ _ - _ _ _ _ _ _ _ _