ML18046A950

Forwards Addl Info on SEP Topic IX-1 Re Fuel Storage,In Response to NRC 810129 Ltr.Info Provided Includes Discussion of Measures Taken to Prevent Loss of Spent Fuel Pool Coolant Inventory & Spread of Radioactivity

ML18046A950
Person / Time
Site:	Palisades
Issue date:	09/29/1981
From:	Vincent R CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.)
To:	Crutchfield D Office of Nuclear Reactor Regulation
References
TASK-09-01, TASK-9-1, TASK-RR NUDOCS 8110060181
Download: ML18046A950 (15)

Text

-consumers Power company General Offices: 212 West Michigan Avenue, Jackson, Ml 49201 * (617) 788-0660 September 29, 1981 Director, Nuclear Reactor Regulation Att Mr Dennis M Crutchfiel.d, Chief Operating Reactors Branch No 5 US Nuclear Regulatory Commission Washington, DC 20555 DOCKET 50-255 - LICENSE DPR PALISADES PLANT - SEP TOPIC IX-1, FUEL STORAGE By letter dated January 29, 1981, the NRC requested additional information concerning SEP Topic IX-1 for the Palisades Plant. The Consumers Power Company responses to the staff questions _are attached.

Robert A Vincent Staff Licensing Engineer CC Director, Region III, USNRC NRC Resident Inspector - Palisades

( 8110060181 810929 '\

J PDR ADOCK 05000255i I p -

I PDR'

- I

PALISADES PLANT - SEP TOPIC IX-1 Response to NRC Letter of January 29, 1981 Question 1:

In reference to Regulatory Guide 1.13, Position C-6 and SRP Acceptance Criteria IIe(2) and (3), describe and discuss the measures taken at Palisades which pro-vide assurance equivalent to current criteria in preventing the loss of spent fuel pool coolant inventory, and/or the spread of radioactivity when the follow-ing is considered:

(a) FSAR Appendix J, amendment dated August 9, 1974, and supplement dated March 1977, as well as FSAR Section 9.4.3.1 describes situations where a significant quantity of coolant could possibly be lost in an un-controlled manner to the extent where the pool cooling system would become inoperative and pool boiling would occur.

Response to Question la:

There are several situations where some coolant can be lost from the pool.

However, in no case is this loss uncontrolled.

Failure of the spent fuel pool cooling system inlet line could result in a loss of a small amount of coolant by siphoning action. However, the inlet line which is cut off approximately two feet below the normal pool level will act as a siphon breaker, terminating the siphoning action when the water level is about 18 feet above the top of the fuel. A failure of the outlet line will also result in the loss of a small amount of coolant down to the level of the bottom of the outlet pipe. This water level is more than 16 feet above the top of the fuel.

In the highly unlikely event that the spent fuel transfer cask is dropped in the cask loading area, the analysis presented in FSAR, Appendix J (Amendment 29) shows that the integrity of the pool will not be damaged. However, there is a remote possibility that the liner plate could lose its integrity. This possi-bility has been reduced by addition of a 1/2 inch thick base plate attached to the bottom of the cask anti-tip frame which will serve to dissipate the load over the cask loading area. In any event, seepage through the concrete will be limited to a few gpm, a flow rate which is well within the makeup system capacity.

For an inlet or outlet line failure, the cooling system will become inoperable.

In this case, the pool will eventually heat up and boiling may occur. However, a backup makeup system (fire water system) is available to makeup the evapo-rative losses and maintain pool water level. Should the pool liner fail due to a cask drop in the cask handling area, the manual makeup system, which has a capacity of 1700 gpm for each of the two pumps, will be more than adequate to maintain pool water level. The backup fire water system is also available should the normal cooling and makeup system fail.

2 Question lb:

The spent fuel pool cooling system is housed within a seismic Class I structure but it apparently is not seismic Class I. Section 9.4.3.1 of the FSAR indi-cates that the failure of the outlet pipe would result in the pool being drained to the level of the outlet pipe. Further, the August 9, 1974 letter states that the load drop analysis shows that the spent fuel pool cooling system lines, as well as fuel assemblies and racks, could be damaged.

Response to Question lb:

In addition to the spent fuel pool structure being seismic Class I, the spent fuel pool cooling and cleanup system is a Class I system and has been designed accordingly. Class I structures, systems and equipment are those whose failure could cause uncontrolled release of radioactivity or those essential for imme-diate and long-term operation following a loss-of-coolant accident. They are designed to withstand the appropriate seismic loads simultaneously with other applicable loads without loss of function. Design bases for Class I Systems and Equipment Design are described in Appendix A to the Palisades FSAR.

A discussion of the load drop analysis on the spent fuel cooling system is discussed in response la. Cask handling in the spent fuel pool is controlled administratively, and is restricted to the cask loading area.

Question le:

Describe and discuss the modifications mentioned in paragraph 5.3 of Appendix J of the FSAR which have been made to prevent the spent fuel shipping cask from tipping and also identify all casks for which the anti-tipping modifications would be applicable.

Response to Question le:

The modification of the cask handling area is mentioned in paragraph Appendix J J.5.2 of the FSAR.

Subsequent to the fuel pool modification and safety analysis submittal of November, 1976, new racks were installed. The cask laydown area may (optionally) contain two 50 - element racks which will normally be used to store fuel during full-core off-loads. The area is presently occupied by a cask anti-tipping frame to allow placement of a spent fuel shipping cask or to allow the use of fuel inspection and repair equipment. The new rack system incorporating the anti-tipping frame is seismic Category I and each rack/frame is restrained to the pool wall at the top and bottom of each rack/frame to prevent excessive movement of the racks/frame under postulated seismic accelerations. Provisions are made in the design to accommodate thermal expansion.

Dimensional and structural restrictions of the anti-tipping frame arrangement presently limit it to accommoation of nominal 25-ton casks. At the present time, there is no intention of making spent-fuel shipments, but spent-fuel strategy planning will include re-evaluation of cask sizes required and their compatibility with the rack/frame installation.

3 Question ld:

Considering the current Technical Specification prohibition on cask .movements in the fuel building, describe the future course of action you intend to follow in order to satisfactorily address NRC concerns.

Response to Question ld:

Reference is made to the Consumers Power Company letter of August 9, 1974 which transmitted Appendix J, "Evaluation of Postulated Cask Drop Accidents", to the Palisades Plant FSAR.

This letter describes the present plant procedures and equipment utilized to increase the margin of safety when handling the spent fuel cask.

The analysis for the amendment was based on the use of a 25 - ton spent fuel shipping cask even though the facilities provided for cask handling at the Palisades Plant were designed to handle a 100 - ton shipping cas.k. However, if CPCo determines that a cask larger than 25 tons should be used, the present design would be reevaluated. The reevaluation would address modifications to make the facilities single-failure proof and bring them into compliance with NUREG 0612.

Question le:

Section 9. 4. 3.1 indicates that the siphon breaker installed in the cooling water inlet line will prevent water from being siphoned from the pool. Assuming a spectrum of single system failures, describe the reasons why it is reasonable to assume the siphon breaker will not fail.

Response to Question le:

The siphon breaker is a passive device which consists of a small pipe extending from the high point in the inlet line to just below the water surface. The only possible failure modes are the crimping or blocking of the line. Blocking of the .siphon breaker, however, is of no real consequence following a previous modification of the cooling water inlet line. The moficiation included the severence of the inlet line about two feet below normal pool level and removal of the remaining section of the line from the pool. The original siphon breaker is still present, but even if it were completely bocked, the pool level would still be maintained approximately 18 feet above the top of the fuel where a siphon would be broken at the elevation of the terminated inlet pipe.

4 Question 2:

In reference to Position C-8 in Regulatory Guide 1.13 demonstrate the capa-bility to provide makeup water, at the maximum required makeup rate, from a seismic Category I system or its equivalent. Also describe all other redun-dant or backup makeup systems such as the unborated fire system.

Response to Question 2:

The Class 1 spent fuel pool cooling system has two 1700 gpm horizontal centrifugal pumps and can be reconfigured to provide fuel pool makeup water from the safety injection and refuel+/-ag water storage tank, which is also part of a Class 1 system.

Backup for the spent fuel pool makeup system is provided by the fire protection system. Water for the fire system is supplied by three full capacity (1500 gpm each) fire pumps. One pump is electrically driven; the other two are diesel engine driven. Either pump will start automatically and can be manually started from the main control room. A jockey pump with local controls is provided to maintain the system full and pressurized.

The fire pumps are housed in the tornado-proof section of the intake structure.

The backup supply header to the auxiliary feedwater pumps is buried under-ground for protection against tornadoes. A cross-connection provided with a hand-operatated valve connects the fire, pump discharge header to the suction header of the auxiliary feedwater pump. One cross-connection provided with a hand-operated valve connects the fire pump discharge header to each of the critical service water lines. Both of the above cross-connections are pro-tected from tornadoes. A header terminating in a blind flange is provided at the spent fuel pool for emergency filling.

The emergency fill for the spent fuel pool is taken off a branch line in the auxiliary building. To provide this source requires the use of a swing-elbow connection after removal of two blind flanges; one on a feeder line and the other on a spent fuel pool cooling recirculation line downstream of the spent fuel pool heater exchangers.

5 Question 3:

Section 7.1 of the November 1, 1976 submittal, relating to the increase in storage capacity, indicates that when spent fuel is stored in the tilt pit the two feet thick tilt pit wall is insufficient to achieve the radiation zoning criteria presented in the FSAR. Assuming, as stated that the older fuel is stored in the tilt pit, describe the measures taken to assure that the FSAR radiation zoning criteria has been met.

Response to Question 3:

To meet the FSAR radiation zoning criteria when older fuel is stored in the tilt pit, high density concrete shielding was added to the north tilt pit wall as shown in Figure 1.

The high density concrete (minimum 195 lb/ft3) is in the form of 6" x 8" x 16" masonry units which are staggered in both the horizontal and vertical directions to avoid radiation streaming through the mortar between the blocks. Calcula-tions performed with the QAD computer code indicate that the FSAR radiation zoning criteria are met when 68 assemblies are stored in the tilt pit after a minimum decay time of 16 weeks. The QAD code calculates both uncollided and collided gamma (and neutron) dose rates, energy deposition and fluxes for a volumetric source represented by a number of point isotropic sources in a.

user specific shield configuration. For each dose point, the straight distance and attenuation in each shield material are calculated for each source point.

The total dose is obtained by summing the contribut1ons from each source point.

In order to simulate the fuel rack as a source, the 225 fuel pins in the 15 x 15 assembly array were homogenized with the racks and water to give a composition called "fuel rack". The source strengths were appropriately diluted over this homogenized source by multiplying by the volume fraction of the "source" occupied by the fuel.

M~ ;'tio "~I

1. • jA ~~, G:J,,crc'le Elt~ 'Z5~o zo" ,,,;,,.

I "'T ""*4

~ J Addition l. l

._,~ tx"s;j c."' ...'""c.---.c....

NUS CORPOl=1ATIOI'

6 Question 4:

The FSAR indicates that it is possible to temporarily tie-in the shutdown cooling system to the spent fuel pool. Identify, describe and discuss the spectrum of adverse situations insofar as the reactor core or stored spent fuel where the temporary tie-in would be employed. The discussion should demonstrate. the adequacy of this operation.

Response to Question 4:

The spent fuel pool cooling system (SFPCS) is a closed loop system utilizing two half-capacity pumps and a full-capacity heat exchange unit consisting of two heat exchangers in series.

Table 6.1 of the November 1976, Spent Fuel Pool Modification Description and Safety Analysis defines the performance of the SFPCS under various single active failure conditions of the SFPCS and shutdown cooling system during normal refueling heat load and full core offload heat load.

The shutdown cooling system tie-~n may be made when the reactor is on shut-down cooling offload conditions to supplement the SFPCS. Table 6.1 defines the consequences of various single active failure conditions when the tie-in is made during full core offload, for:

• Mechanical failure of a SFPCS pump.

Mechanical failure of a shutdown cooling (LPSI) pump.

• Mechanical failure of a CCW pump.

• Loss of offsite power.

• Loss of offsite power and failure of one diesel generator.

Air failure to valve on CCW inlet to SFPCS heat exchangers.

Air failure to valve on inlet of shutdown heat exchangers.

These consequences are satisfactorily dispositioned in Table 6.1.

The tie-in may also be made when the reactor is on shutdown cooling if compon-ents of the SFPC have to be spared or repaired during either normal refueling heat load or full core offload heat load. The consequences of credible single active failures in other systems during a tie-in for this reason are defined and satisfactorily dispositioned in Table 6.1 for the most adverse situation of full core offload heat load.

During power operation, a single active failure of the SFPCS could occur with only a normal refueling heat load, af'ter substantial decay heat removal, and the tie-in could be made. The only credible failures of the shutdown cooling system during such a tie-in are defined and satisfactorily dispositioned in Table 6.1 and (if safety injection were required) additionally in Section 6.1 of the FSAR. It must be noted, however, that this cross connection would render LPSI and one containment spray header inoperable. With existing tech-nical specification limitations, therefore, cross connecting in this plant condition would only be acceptable in an emergency.

TABLE 6-l PALISADES PLANT - SPENT FUEL POOL COOLING SYSTEM (SFPCS) SINGLE ACTIVE FAILURE ANALYSIS ranure Mode Normal Refueling Heat Load Pull Core orrload Heat Load 16.9

• 106 BtU/hr 26.* g 105 BTU/b Spent Fuel Hecllanlcll Second pump Ja ~peratlonal. Co~plate lnven* Second puep ls operational. Shutdown ooollng *r**

Cooling P11sp rallure torr or_oparo' available tor rapid pump tem ia avollablo and can ~e put 1nto operation bf reralra, it needc1. llovever, maximum pool manual oonnectlons between the two systems.

tempe_rature vUl reach 118°r, Vlthout the_ shutdown oyatom, the pool t**P*r&*

ture will reach 13~°F. With the ahuldovn cooling oy3tem also in operation, pool temptrature vlll be reduced to 103°F.

l.Ov Pr*eel11'e Hechan1oa1 Shutdovn arstem la not required tor nort1a1 The second I.PSI pump and two shutdown heat ex-

eretr InJoo* Pallure cooling, No effect on SFPCS, chnngera, end lhe SFPCS are avail*ble ror coollng.

Uon (LPSI) Fool tc~perature vlll be less than ln the case of Pu:p (Shutdovn ESP Du' lo failure.

Co'!>l1ng Pucp) co~ponent ~cllanJca1 Ko errect*on SFPCS, aa tvo 213 capacltr Ko errect on SFPCS or on fthutdovn cooling *1**

Coollnr; \later Fallure CCW pucps are available. tem, ftS two 213 capacity CCV pumps are ivallable.

(CCII) Pur:p Ortslle Fover !hctrloll tmergencf Pover la avallable. Hanual atart* Eeersenor paver la avalleble. Hanual atartlng or Fellure lng or SFP and CCW pumps la pooslbla, SFP puep3 1 CCW pum~s end LPSI pumps la ~~ssible, Hence, no erreot on SfPCS performance, Hence, no effect on SFPCS and on ahutdown eoolSn&

_ay:stems.

ortslte Pover Electrical Diesel generator Ko.Z lo available, Hanua1 Diesel generator Ho. 2 la avalleble. One LPSI ond Dle'8l and/or otartlng or one SFP pu~p and one CCV pucp are pua:p, ono CCW pump, and one SFPC puep are. n*ll*

Cenerator Kechanlcel po3:ilble. Second SFP ~ucp m~y be otarled '*ble ror manual startup, Pool temperature will llo, I (ESP later, it tie-in breakers can be operated. not e1ceed 109°F, Bus lo) Pool temperature will not exceed 118°F.

Ur OP"r*ted .Alr Fallure Slnsle failures ln the alr ay,tem other than Both LPSl pumps and hut *uchangera are ualhble.

Yal .. ::v-09u ruptur~ or air piping to valve cannot cau'a .

(On CCW Inlet valve clo:iuro a!!I rcdu11dant compres!!lor:i, cross to Sfi1C hta\. conntcts and air atorage tanks are avail-uchangers) able ror valve operation.

CY-3C5S (At Air ranur* Ho errect on Sf PCS. Slngle tallure' ln the atr 111tem other than rup.

lnlet. to tolb ture or atr plplng to valve cannot oauea valve

ihutdo"n t.eat. closure aa redundant compresaore, oroas oonneote,

• ~ctunli"' on and air atorage tanks, are available ror valve 1.P'.;l/,huldovn operation.

ay:ltG

7 Investigation has disclosed one case when the tie-in must not be made. A review of the validity of the projected consequences will be conducted and a revision to the pertinent plant SOP will be made if necessary, prohibiting the tie-in when:

• The reactor is on shut-down cooling, and

• The reactor, containing fuel, is under pressure.

During a tie~in under these conditions, the shutdown cooling (LPSI) pumps could take suction from both the SFP and the reactor vessel, and because of the pressure in the reactor vessel, would discharge preferentially to the SFP.

Shutdown cooling water to the reaetor may be limited and contaminated water discharged to the SFP.

8 Question 5:

Describe and discuss the reasons for concluding that the spent fuel pool cool-ing system piping, fittings and valves which meet. the requirements of ASA B31.l is acceptable considering the requirements presented in Table 1 in Regulatory Guide 1.26.

Response to Question 5:

NRC Regulatory Guide 1.26 specifies that the spent fuel pool cooling system be designed to Group C quality standards. Current practice, therefore, would specify that the cooling system piping, fittings and valves must meet the requirements of ASME Boiler and Pressure Vessel Code,Section III, "Nuclear Power Plant Components", Class 3. However, the design of the spent fuel cooling system to meet the requirement of ANSI B31.l Power Piping is accept-able considering that the requirements of both the codes are essentially the same. Specifically:

o The allowable stress limits given in Tables 1-7.0 of the appendices of ASME Section III are id~ntical to those given in Appendix A of ANSI B31.l.

o Pressure-temperature ratings for piping products: For piping products having specified ratings, the standards for ASME Section III Class 3 components given in Table ND-3132-1 are identical to the standards for ANSI B31.l in Table 126.1.

For piping products not having specific ratings, both the codes specify that the manufacturer's recommended press.ure ratings should not be exceeded. The considerations for local conditions and transients addressed by the two codes are nearly the same. The differences are insignificant.

o Allowances for the effect of corrosion and erosion, threading and grooving, mechanical strength, longitudinal weld joint efficiency factors and the steel casting quality factors discussed in Article ND-3613 of the ASME B&PV Code and in Article 102.4 of the ANSI B31.l are the same.

o Design Considerations:

Article ND-3621, Design and Service Loadings of the ASME Code and the Article 101.4, Ambient Influences of ANSI B31.l are identical.

Article ND-3622, Dynamic Effects (which include impact, earthquake and vibra-tion) of the ASME Code are approximately the same as the Article 101.5, Dynamic Effects of the ANSI B31.l. Although ANSI B31.l does not address such items a$ exposed piping and relief and safety valve thrust., these items do not apply to the spent fuel cooling system.

Article ND-3623, Weight Effects of the ASME Code is identical to Article 101.6, Weight Effects of ANSI B31.l.

o Pressure design of piping: The pressure design of piping components in the ASME Code is very similar to that in the ANSI B31.l. Minimum wall thickness of the pipe is determined by the same equation (ND-3641.1 of ASME and 104.1.2 of ANSI). The allowable working pressure of the pipe is determined from the same equation in both the codes. The requirements for curved pipes in the two codes are very nearly the same. The requirements for intersections, which include unreinforced and reinforced branch connections, extruded outlets,

9 branch connections subjected to external pressure, mitres, attachments and closures in both ASME III, Class 3 and ANSI B31.l are the same. The several equations used to determine the required reinforcement thickness are also identical.

o Design requirements that the various loads on the piping must meet are given in Article ND-3650 of the ASME Section III, Class 3 code and in Article 104.8.1 of the ANSI B31.l. These requirements, for sustained loads, occasional loads, thermal expansion stresses and sustained plus thermal expansion loads given in Equations 8, 9, 10 and 12 of ASME Section III, Class 3 are the same as Equations lla, 12a, 13a and 14a of ANSI B31.l.

The allowable stress range for expansion stresses given in Article ND-3611.2(e) of the ASME Section III Class 3 is identical to that given in Article 102.3.2(c) of the ANSI B31.l Code.

The determination of moments and section modulus are the same according to both the codes.

The piping flexibiiity and the stress intensity factors according to ASME Section III Class 3 given in Article ND-3673.2 (associated with Figures ND-3673.2(b)-l through ND-3673.2(b)-5) are identical to those according to ANSI B31.l (Appendix D).

Question 6:

Identify and discuss where the Technical Specifications for Palisades are not in accord with the current Technical Specification as it relates to new and spent fuel storage and associated refueling operations. For each deviation demonstrate that when other plant features or procedures are taken into con-sideration your present Technical Specification provides an equivalent level of safety or describe and discuss what additional measures must be implemented to bring Palisades Technical Specifications up to current practices.

Response to Question 6:

The attached table provides a direct comparison between the Standard Technical Specifications for CE plants and the current Palisades Technical Specifications.

TECHNICAL SPECIFICATION COMPARISON STANDARD T.S. FOR CE PLANTS PALISADES T.S.

Section Purpose/Remarks Section Purpose/Remarks 3,9,7 - Prohibits crane movement of 3.13.b - Prohibits crane movement of any loads in excess of lbs material past the SFP unless over fuel assemblie-s~- interlocks are operable or unless crane is under direct administra-tive control of a supervisor.

NOTE: Interlocks prevent movement of a load over the SFP.

3.21.l - Provides specific restrictions on movement of shielded shipping casks in the vicinity of the SFP.

The entire issue of movement of heavy loads near safety-related equipment is being addressed in response to NRC Generic Letter 81-07 dated December 22, 1980. CPCo responses include letters of May 15, 1981; July 6, 1981; and September 23, 1981. .

4.9.7 - Requires demonstration of crane 3.13.b and Table 3.17.4 - Requires crane interlocks interlock operability within to be operable whenever material is 7 days prior to movement of moved past the SFP except when special loads in excess of lbs administrative controls are imposed over fuel assemblies and once on crane operation. The interlocks per 7 days therea~er. are checked monthly as a preventive maintenance item. Tech. Specs. do not specify a test frequency, but do meet the intent of the STS.

3.9.11 - Specifies minimum water level for SFP at 23' over fuel. Equivalent T.S. does not exist for Palisades. Routine operator inspec-Requires verification of SFP tion tours which include an inspection water level each 7 days. of the spent fuel pool area are made on a shift frequency, however. In addition, an SFP low level alarm is provided which is actuated at a level approximately 18' above the top of the fuel (el. 646 1 ) . Operability of this alarm is periodically verified as a preventive maintenance item.

2 Section Purpose/Remarks Section Purpose/Remarks 3.9.12 - Requires two SFP air cleanup 3.8.4 - Requires the ventilating system, systems to be operable or one including the charcoal filter, cleanup system to be in opera- to be in operation whenever irra-tion (through HEPA filter and diated fuel is being handled in the charcoal adsorber) whenever SFP or whenever refueling operations fuel is moved in the pool or are being performed with the equip-when crane operations are ment door open. This is consistent performed with loads over the with STS.

pool.

As discussed above, movement of other heavy loads is being addressed in response to .Generic Letter 81-07.

Movement of loads over the pool is generally prohibited unless special administrative controls are in effect.

4.9.12 - Specifies that SFP air cleanup Table 4.2.2, Item 11 - Requires efficiency test of system operability be verified HEPA and charcoal filters during each each 31 days; and system clean- refueling shutdown and whenever work up efficiency be verified each on filters could alter their integrity.

18 months, after structural Specified efficiency is 99%.

maintenance, or following painting, fire or chemical release which could contaminate filters. Specified efficiency is 99% (Palisades calculations assume 90%). Also specifies system flow rate measurements and laboratory tests of char-coal after every 720 hours0.00833 days <br />0.2 hours <br />0.00119 weeks <br />2.7396e-4 months <br /> of operation.

5.6 Provides miscellaneous design 5.4.2 - Provides miscellaneous design and opera-information for fuel racks, ting information for SFP. Differences pool water level and storage from STS have no practical effect.

capacity.

,l

-~.

3 Section Purpose/Remarks Section Purpose/Remarks Equivalent does not apparently Table 4.2.1, Item 6 - Requires monthly test to verify exist in STS. minimum SFP boron concentration.

Requires continuous monitoring of bulk water temperature when bundles which have decayed for less than one year are stored in tilt pit racks.